Sample records for observed large circular

  1. GRAIN ALIGNMENT IN OMC1 AS DEDUCED FROM OBSERVED LARGE CIRCULAR POLARIZATION

    SciTech Connect

    Matsumura, M. [Faculty of Education, Kagawa University, Takamatsu, Kagawa 760-8522 (Japan); Bastien, P. [Departement de physique and Centre de recherche en astrophysique du Quebec, Universite de Montreal, C.P.6128, Succursale Centre-ville, Montreal, Quebec, H3C 3J7 (Canada)], E-mail: matsu@ed.kagawa-u.ac.jp

    2009-05-20

    The properties of polarization in scattered light by aligned ellipsoidal grains are investigated with the Fredholm integral equation method and the T-matrix method, and the results are applied to the observed circular polarization in OMC1. We assume that the grains are composed of silicates and are ellipsoidal (oblate, prolate, or triaxial ellipsoid) in shape with a typical axial ratio of 2:1. The angular dependence of circular polarization p{sub c} on directions of incident and scattered light is investigated with spherical harmonics and associated Legendre polynomials. The degree of circular polarization p{sub c} also depends on the Rayleigh reduction factor R, which is a measure of imperfect alignment. We find that p{sub c} is approximately proportional to R for grains with |m|x {sub eq} {approx}< 3 - 5, where x {sub eq} is the dimensionless size parameter and m is the refractive index of the grain. Models that include those grains can explain the observed large circular polarization in the near-infrared, {approx}15%, in the southeast region of the BN object in OMC1, if the directions of incidence and scattering of light is optimal, and if grain alignment is strong, i.e., R {approx}> 0.5. Such a strong alignment cannot be explained by the Davis-Greenstein mechanism; we prefer instead an alternative mechanism driven by radiative torques. If the grains are mixed with silicates and ice, the degree of circular polarization p{sub c} decreases in the 3 {mu}m ice feature, while that of linear polarization increases. This wavelength dependence is different from that predicted in a process of dichroic extinction.

  2. Grain Alignment in OMC1 as Deduced from Observed Large Circular Polarization

    E-print Network

    Matsumura, Masafumi

    2009-01-01

    The properties of polarization in scattered light by aligned ellipsoidal grains are investigated with the Fredholm integral equation method (FIM) and the T-matrix method (Tmat), and the results are applied to the observed circular polarization in OMC1. We assume that the grains are composed of silicates and ellipsoidal (oblate, prolate, or tri-axial ellipsoid) in shape with a typical axial ratio of 2:1. The angular dependence of circular polarization p_c on directions of incident and scattered light is investigated with spherical harmonics and associated Legendre polynomials. The degree of circular polarization p_c also depends on the Rayleigh reduction factor R which is a measure of imperfect alignment. We find that p_c is approximately proportional to R for grains with |m|x_{eq} 0.5. Such a strong alignment cannot be explained by the Davis-Greenstein mechanism; we prefer instead an alternative mechanism driven by radiative torques. If the grains are mixed with silicates and ice, the degree of circular pola...

  3. Large Eddy Simulation of a flow through circular tube bundle

    Microsoft Academic Search

    M. Salinas-Vázquez; M. A. de la Lama; W. Vicente; E. Martínez

    2011-01-01

    The Large Eddy Simulation approach is used to perform a numerical simulation of a flow around a circular tube bundle. The model uses the immersed boundaries technique to represent tube geometry in the Cartesian grid. Simulation is conducted in an area away from the boundaries, where the flow is considered homogenous and, thus, the three Cartesian directions are considered periodic.

  4. Circular structures of large scale and great age on the earth's surface

    Microsoft Academic Search

    J. M. Saul

    1978-01-01

    It is pointed out that the earth's surface exhibits faint circular patterns which have not been described before. These circles are characterized by near perfection of outline, by the presence of topographic highs (rims) along parts of their circumferences, and by their generally large scale (diameters from 7 to 700 km). Circles of this nature have been observed clearly in

  5. 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.

  6. Large-amplitude circularly polarized electromagnetic waves in magnetized plasma

    SciTech Connect

    Vasko, I. Y., E-mail: vaskoiy@gmail.com; Artemyev, A. V.; Zelenyi, L. M. [Space Research Institute, RAS, Moscow (Russian Federation)] [Space Research Institute, RAS, Moscow (Russian Federation)

    2014-05-15

    We consider large-amplitude circularly polarized (LACP) waves propagating in a magnetized plasma. It is well-known that the dispersion relation for such waves coincides with the dispersion relation given by the linear theory. We develop the model of LACP wave containing a finite population of Cerenkov resonant particles. We find that the current of resonant particles modifies the linear dispersion relation. Dispersion curves of low-frequency (i.e., whistler and magnetosonic) waves are shifted toward larger values of the wave vector, i.e., waves with arbitrarily large wavelengths do not exist in this case. Dispersion curves of high-frequency waves are modified so that the wave phase velocity becomes smaller than the speed of light.

  7. Propagation of Large Barkhausen Discontinuities, III. Effect of a Circular Field with Torsion

    Microsoft Academic Search

    L. Tonks; K. J. Sixtus

    1933-01-01

    The propagation of large Barkhausen discontinuities along a nickel-iron (15 Ni 85 Fe) wire which is under tension alone is practically unaffected by the presence of a large circular field caused by a current through the wire, but such a circular field creates large effects if the wire is twisted. By treating the critical field as a vector having the

  8. Large-eddy simulation of flow past a circular cylinder

    NASA Technical Reports Server (NTRS)

    Mittal, R.

    1995-01-01

    Some of the most challenging applications of large-eddy simulation are those in complex geometries where spectral methods are of limited use. For such applications more conventional methods such as finite difference or finite element have to be used. However, it has become clear in recent years that dissipative numerical schemes which are routinely used in viscous flow simulations are not good candidates for use in LES of turbulent flows. Except in cases where the flow is extremely well resolved, it has been found that upwind schemes tend to damp out a significant portion of the small scales that can be resolved on the grid. Furthermore, it has been found that even specially designed higher-order upwind schemes that have been used successfully in the direct numerical simulation of turbulent flows produce too much dissipation when used in conjunction with large-eddy simulation. The objective of the current study is to perform a LES of incompressible flow past a circular cylinder at a Reynolds number of 3900 using a solver which employs an energy-conservative second-order central difference scheme for spatial discretization and compare the results obtained with those of Beaudan & Moin (1994) and with the experiments in order to assess the performance of the central scheme for this relatively complex geometry.

  9. Analysis of finite arrays of axially directed printed dipoles on electrically large circular cylinders

    Microsoft Academic Search

    Vakur B. Ertürk; Roberto G. Rojas; Kit Wing Lee

    2004-01-01

    Various arrays consisting of finite number of printed dipoles on electrically large dielectric coated circular cylinders are investigated using a hybrid method of moments\\/Green's function technique in the spatial domain. This is basically an \\

  10. Design of MEMS PZT circular diaphragm actuators to generate large deflections

    Microsoft Academic Search

    Eunki Hong; Susan Trolier-McKinstry; Robert L. Smith; Silai V. Krishnaswamy; Carl B. Freidhoff

    2006-01-01

    This paper presents a design of lead zirconate titanate (PZT) circular diaphragm actuators to generate large deflections. The actuators utilize a unimorph structure consisting of an active PZT and a passive thermally grown SiO2 layer. The diaphragm structures were formed by deep reactive ion etching (DRIE). Two different designs, where the PZT layer in the diaphragm actuators was driven by

  11. Life cycle of a mesoscale circular gust front observed by a C-band Doppler radar

    E-print Network

    Ribes, Aurélien

    Life cycle of a mesoscale circular gust front observed by a C-band Doppler radar in West Africa convection to its traveling gust front. The analysis of the observations during the transitions from), focusing predominantly on triggering by boundaries: frontal zones, drylines, gust fronts, boundary

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

    Microsoft Academic Search

    G. R. Rohrkaste

    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

  13. Large eddy simulation of pulsating flow over a circular cylinder at subcritical Reynolds number

    Microsoft Academic Search

    Chunlei Liang; George Papadakis

    2007-01-01

    The pulsating cross-flow over a single circular cylinder at the subcritical Reynolds number ReD=2580 is studied with the large eddy simulation (LES) technique using the standard Smagorinsky model as well as a dynamic model in which the test filtered quantities are evaluated through a truncated Taylor series expansion. The filtered equations are discretised using the finite volume method in an

  14. A pattern recognition scheme for large curvature circular tracks and an FPGA implementation using hash sorter

    SciTech Connect

    Wu, Jin-Yuan; Shi, Z.; /Fermilab

    2004-12-01

    Strong magnetic field in today's colliding detectors causes track recognition more difficult due to large track curvatures. In this document, we present a global track recognition scheme based on track angle measurements for circular tracks passing the collision point. It uses no approximations in the track equation and therefore is suitable for both large and small curvature tracks. The scheme can be implemented both in hardware for lower-level trigger or in software for higher-level trigger or offline analysis codes. We will discuss an example of FPGA implementations using ''hash sorter''.

  15. 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.

  16. Observations of Kelvin-Helmholtz instability at the air-water interface in a circular domain

    NASA Astrophysics Data System (ADS)

    Bye, John A. T.; Ghantous, Malek

    2012-03-01

    We present an analysis of Kelvin-Helmholtz instability in a circular domain in the limit of the azimuthal integer wavenumber, n ? ? which reproduces the classical results for a rectilinear geometry at the rim, provided that the additional condition that the surface current to surface wind ratio is (?1/?2)1/2 where ?1 and ?2 are respectively the densities of air and water, is satisfied. Experiments were carried out in a circular rig of radius 0.19 m in which a family of unstable waveforms with n ? 60 were observed with properties (including the additional condition) in approximate agreement with theory. The additional condition is consistent with the absence of a surface shear stress in the instability process.

  17. Nonlinear evolution of a large-amplitude circularly polarized Alfven wave: Low beta

    NASA Technical Reports Server (NTRS)

    Ghosh, S.; Goldstein, M. L.

    1994-01-01

    The nature of turbulent cascades arising from the parametric instabilities of a monochromatic field-aligned large-amplitude circularly polarized Alfven wave is investigated via direct numerical simulation for the case of low plasma Beta and no wave dispersion. The magnetohydrodynamic code permits nonlinear couplings in the parallel direction to the ambient magnetic field and one perpendicular direction. Compressibility is included in the form of a polytropic equation of state. Anisotropic turbulent cascades, similar to those found in early incompressible two-dimensional simulations, occur after nonlinear saturation of the parallel propagating decay instability. The turbulent spectrum can be divided into three regimes: the lowest wave numbers are dominated by lower sideband remnants of the parametric process, intermediate wave numbers display nearly incompressible dynamics, and the highest wave numbers are dominated by acoustic turbulence.

  18. Functional relationship of longitudinal and circular layers of the muscularis externa of the rabbit large intestine

    PubMed Central

    McKirdy, H. C.

    1972-01-01

    1. The functional relationship of the longitudinal and circular layers of the muscularis externa of the rabbit large intestine has been studied in a flat preparation. 2. Evidence is presented that mechanical activity can be recorded independently and simultaneously from the two muscle layers of the flat preparation. Such evidence accrues mainly from results obtained from the flat preparation in response to various drugs. 3. During spontaneous rhythmic contractions and during the response to pelvic (parasympathetic) nerve stimulation, both layers show similar activity, never opposite or reciprocal activity. 4. In this flat preparation, the mechanism controlling the level of sustained tension (i.e. `tone') may be dissociable, within limit, from the mechanism controlling rhythmic contractions. ImagesPlate 1 PMID:4650938

  19. NUMERICAL INVESTIGATION ON LARGE CIRCULAR GUIDEHOLE FOR CONTROLLED CONTOUR BLASTING IN TUNNEL EXCAVATION

    NASA Astrophysics Data System (ADS)

    Fukuda, Daisuke; Kaneko, Katsuhiko; Ishiyama, Koji; Naito, Masashi

    Achievement of good resultant tunnel profile due to controlled contour blasting (CCB) in tunnel excavation has been of great importance for reduction of required cost. For this purpose, a new CCB technique was developed and has been in practical use, which applies unloaded large circular boreholes called guidehole having twice the diameter of charge hole and sets these guideholes between contour charge holes. This paper numerically investigated influence of the guidehole diameter on smoothness of resultant fracture plane in case of blasting with one free face. First we conducted stress analyses around guidehole walls for various borehole pressure wave forms applied in charge hole and showed that the stress concentration level was dependent on the guidehole diameter. Then we conducted dynamic fracturing process analyses considering heterogeneity of rock mass. We showed that the application of guidehole with larger diameter was effective for achieving smoother resultant fracture plane and discussed its mechanism in detail.

  20. 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.

  1. Null reconstruction of orthogonal circular polarization hologram with large recording angle.

    PubMed

    Wu, An'an; Kang, Guoguo; Zang, Jinliang; Liu, Ying; Tan, Xiaodi; Shimura, Tsutomu; Kuroda, Kazuo

    2015-04-01

    We report on the null reconstruction of polarization volume hologram recorded by orthogonal circularly polarized waves with a large cross angle. Based on the recently developed tensor theory for polarization holography, the disappearance of the reconstruction was analytically verified, where a nice agreement was found between the experimental and theoretical results. When the polarization and intensity hologram attain a balance, not only the null reconstruction but also the faithful reconstruction can be realized by the illumination of the orthogonal reference wave and original reference wave. As a consequence of the hologram recorded without paraxial approximation, the null reconstruction may lead to important applications, such as a potential enhancement in optical storage capacity for volume holograms. PMID:25968725

  2. On the solution of a class of large body problems with full or partial circular symmetry by using the finite-difference time-domain (FDTD) method

    Microsoft Academic Search

    Wenhua Yu; Dean Arakaki; Raj Mittra

    2000-01-01

    This paper presents an efficient method to accurately solve large body scattering problems with partial circular symmetry. The method effectively reduces the computational domain from three to two dimensions by using the reciprocity theorem. It does so by dividing the problem into two parts: a larger 3-D region with circular symmetry, and a smaller 2-D region without circular symmetry. An

  3. Nonlinear characteristics of a circular plate piezoelectric harvester with relatively large deflection near resonance

    Microsoft Academic Search

    Huan Xue; Hongping Hu

    2008-01-01

    Based on the von Karman thin circular plate theory, we report in this paper the analysis of the nonlinear behavior of a power harvester consisting of a circular piezoelectric plate and an electric resistance. Dependence of the output power of the harvester upon driving frequency for different electric loads and different applied forces is obtained. Numerical results show that the

  4. Life Cycle of a Mesoscale Circular Gust Front Observed by a C-Band Doppler Radar in West Africa

    E-print Network

    Guichard, Francoise

    Life Cycle of a Mesoscale Circular Gust Front Observed by a C-Band Doppler Radar in West Africa shallow convection to its traveling gust front. The analysis of the observations during the transitions- aries: frontal zones, drylines, gust fronts, boundary layer rolls, bores, and land surface effects

  5. Application of large eddy simulation to flow past a circular cylinder

    SciTech Connect

    Lu, X.; Dalton, C.; Zhang, J. [Univ. of Houston, TX (United States). Dept. of Mechanical Engineering

    1996-12-31

    A steady approach flow around a circular cylinder is investigated by using a large eddy simulation (LES) with the Smagorinsky subgrid scale model. A second-order accurate in time fractional-step method and a combined finite-difference/spectral approximation are employed to solve the filtered three-dimensional incompressible Navier-Stokes equations. To demonstrate the viability and accuracy of the method, the authors present results at Reynolds numbers of 100, 3 {times} 10{sup 3}, 2 {times} 10{sup 4} and 4.42 {times} 10{sup 4}. At Re = 100, the physical flow is two-dimensional and the calculation is done without use of the LES method. For the higher values of Re, the flow in the wake is three-dimensional and turbulent and the LES method is necessary to describe the flow accurately. Calculated values of lift and drag coefficients and Strouhal number are in good agreement with the experimentally determined values at all of the Reynolds numbers for which calculations were done.

  6. Circularized Chromosome with a Large Palindromic Structure in Streptomyces griseus Mutants

    Microsoft Academic Search

    Tetsuya Uchida; Naoto Ishihara; Hiroyuki Zenitani; Keiichiro Hiratsu; Haruyasu Kinashi

    2004-01-01

    Streptomyces linear chromosomes display various types of rearrangements after telomere deletion, including circularization, arm replacement, and amplification. We analyzed the new chromosomal deletion mutants Streptomyces griseus 301-22-L and 301-22-M. In these mutants, chromosomal arm replacement resulted in long terminal inverted repeats (TIRs) at both ends; different sizes were deleted again and recombined inside the TIRs, resulting in a circular chromosome

  7. Nonlinear characteristics of a circular plate piezoelectric harvester with relatively large deflection near resonance.

    PubMed

    Xue, Huan; Hu, Hongping

    2008-09-01

    Based on the von Karman thin circular plate theory, we report in this paper the analysis of the nonlinear behavior of a power harvester consisting of a circular piezoelectric plate and an electric resistance. Dependence of the output power of the harvester upon driving frequency for different electric loads and different applied forces is obtained. Numerical results show that the output power exhibits multi-valuedness and a jump phenomenon near resonance. PMID:18986906

  8. 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...

  9. Direct observation of depth profile of magnetic moment by magnetic circular dichroism

    NASA Astrophysics Data System (ADS)

    Mun, Bongjin Simon; Yang, See-Hun; Mannella, Norman; Kay, Alex W.; Kim, Sang-Koog; Kortright, Jeffrey B.; Underwood, Jim H.; Hussain, Zahid; Fadley, Charles S.

    2001-03-01

    The magnetic properties at the interface between Fe and Cr wedge layers are investigated with a new depth-resolved soft x-ray photoemission spectroscopy (SXPS)[1], combined with magnetic circular dichroism (MCD). The layers of Fe (10 A)/ Cr (50 A wedge- shaped) are grown on a periodic multilayer (B 4 C(22.5A)/W(17.1 A)) _40, which provides the strong standing wave effects of 40 The unique angular dependence of photoelectron intensity of Fe and Cr has been observed at each different Cr wedge thickness and show excellent agreement with the theoretical calculation. To maximize the enhancement and contrast of standing wave effect inside of sample, the sample position is tuned to the Bragg angle position, at which the MCD measurement with SXPS along the different thickness of Cr wedge layer provides the depth profile of the magnetic moment of Fe and Cr. A strong antiparallel coupling across the interface of Cr magnetic moment is clearly resolved while the apparent reduction of Fe magnetic moment is observed near the interface. This observation is consistent with the other works on the same system [2] and even describes how the magnetic moment behaves inside of the sample from the top surface to the interface in one single sample preparation. In this experiment, a new depth-resolved SXPS has been successfully implemented to magnetic multilayer system and prove to be powerful technique to study the buried interface of magnetic system, as proposed by our former work [1]. [1] S.-H. Yang, B. S. Mun, A.W. Kay, S.-K. Kim, J. B. Kortright , J.H. Underwood, Z. Hussain, C. S. Fadley, Surf. Sci. 461 L557-L564 (2000) [2] G. Panaccione, F. Sirotti, E. Narducci, and G. Rossi, Phys. Rev. B 55, 389 (1997)

  10. Observations of large transient magnetospheric electric fields

    NASA Technical Reports Server (NTRS)

    Aggson, T. L.; Heppner, J. P.

    1977-01-01

    Transient electric field events were observed with the long, double probe instrumentation carried by the IMP-6 satellite. Nine, clearly defined, exceptionally large amplitude events are presented here. The events are observed in the midnight sector at geocentric distances 3.5 to .5.5 R sub e at middle latitudes within a magnetic L-shell range of 4.8 to 7.5. They usually have a total duration of one to several minutes, with peak power spectra amplitudes occurring at a frequency of about 0.3 Hz. The events occur under magnetically disturbed conditions, and in most cases they can be associated with negative dH/dt excursions at magnetic observatories located near the foot of the magnetic field line intersecting IMP-6. The magnetospheric motions calculated for these electric fields indicated a quasi-stochastical diffusive process rather than the general inward magnetospheric collapsing motion expected during the expansive phases of auroral substorm activity.

  11. Experimentally Observed Strain Distributions Near Circular Discontinuities of AA6061-T6 Extrusions During Axial Crush

    Microsoft Academic Search

    N. Turton; S. Y. Jin; A. Majumder; H. An; V. Vijayan; W. Altenhof; D. Green

    2011-01-01

    An experimental investigation to determine the strain distribution and collapse behaviour for AA6061-T6 square cross-sectional\\u000a extrusions with and without circular discontinuities under quasi-static axial compressive loading was completed. Three-dimensional\\u000a digital image correlation (DIC) was utilized for strain assessment. In order to validate the results of the optical strain\\u000a measurement system, tensile tests were first conducted employing both the DIC technique

  12. Does the stationary viscous flow around a circular cylinder exist for large Reynolds numbers? A numerical solution via variational imbedding

    NASA Astrophysics Data System (ADS)

    Christov, Christo I.; Marinova, Rossitza S.; Marinov, Tchavdar T.

    2009-04-01

    We propose an approach to identifying the solutions of the steady incompressible Navier-Stokes equations for large Reynolds numbers. These cannot be obtained as initial-value problems for the unsteady system because of the instability of the latter. Our approach consists of replacing the original steady-state problem for the Navier-Stokes equations by a boundary-value problem for the Euler-Lagrange equations for minimization of the quadratic functional of the original equations. This technique is called Method of Variational Imbedding (MVI) and in this case it leads to a system of higher-order partial differential equations, which is solved by means of an operator-splitting method. As a featuring example we consider the classical flow around a circular cylinder which is known to lose stability as early as for . We find a stationary solution with recirculation zone for Reynolds numbers as large as . Thus, new information about the possible hybrid flow regimes is obtained.

  13. Displacement Field and Elastic Energy of a Circular Twist Disclination for Large Deformations - an Example how to Treat Nonlinear Boundary Value Problems with Computer Algebra Systems

    Microsoft Academic Search

    Alexander Unzicker; Karl Fabian

    2003-01-01

    A circular twist disclination is a nontrivial example of a defect in an elastic continuum that causes large deformations. The minimal potential energy and the corresponding displacement field is calculated by solving the Euler-Lagrange-equations. The nonlinear incompressibility constraint is rigorously taken into account. By using an appropriate curvilinear coordinate system a finer resolution in the regions of large deformations is

  14. 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.

  15. 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.

  16. Observation of x-ray absorption magnetic circular dichroism in well-characterized iron-cobalt-platinum multilayers

    SciTech Connect

    Jankowski, A.F.; Waddill, G.D.; Tobin, J.G.

    1993-04-01

    Magnetic circular dichroism in the Fe 2p x-ray absorption is observed in multilayers of(Fe9.5{Angstrom}/Pt9.5{Angstrom}){sub 92}. The magnetization and helicity are both in the plane of this multilayer which is prepared by magnetron sputter deposition. This sample is part of a study to examine magnetization in the ternary multilayer system of FeCo/Pt. Lattice and layer pair spacings are measured using x-ray scattering. The atomic concentration profiles of the multilayer films are characterized using Auger electron spectroscopy coupled with depth profiling. Conventional and high resolution transmission electron microscopy are used to examine the thin film, growth morphology and atomic structure.

  17. Application of the modified method of multiple scales to the bending problems for circular thin plate at very large deflection and the asymptotics of solutions (I)

    Microsoft Academic Search

    Bissanga Gabriel; Jiang Furu

    1998-01-01

    In this paper, the modified method of multiple scales is applied to study the bending problems for circular thin plate with\\u000a large deflection under the hinged and simply supported edge conditions. The series solutions are constructed, the boundary\\u000a layer effects are analysed and their asymptotics are proved.

  18. 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 [Formula: see text] 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. PMID:25008961

  19. Genome Analysis of a Glossina pallidipes Salivary Gland Hypertrophy Virus Reveals a Novel, Large, Double-Stranded Circular DNA Virus?

    PubMed Central

    Abd-Alla, Adly M. M.; Cousserans, François; Parker, Andrew G.; Jehle, Johannes A.; Parker, Nicolas J.; Vlak, Just M.; Robinson, Alan S.; Bergoin, Max

    2008-01-01

    Several species of tsetse flies can be infected by the Glossina pallidipes salivary gland hypertrophy virus (GpSGHV). Infection causes salivary gland hypertrophy and also significantly reduces the fecundity of the infected flies. To better understand the molecular basis underlying the pathogenesis of this unusual virus, we sequenced and analyzed its genome. The GpSGHV genome is a double-stranded circular DNA molecule of 190,032 bp containing 160 nonoverlapping open reading frames (ORFs), which are distributed equally on both strands with a gene density of one per 1.2 kb. It has a high A+T content of 72%. About 3% of the GpSGHV genome is composed of 15 sequence repeats, distributed throughout the genome. Although sharing the same morphological features (enveloped rod-shaped nucleocapsid) as baculoviruses, nudiviruses, and nimaviruses, analysis of its genome revealed that GpSGHV differs significantly from these viruses at the level of its genes. Sequence comparisons indicated that only 23% of GpSGHV genes displayed moderate homologies to genes from other invertebrate viruses, principally baculoviruses and entomopoxviruses. Most strikingly, the GpSGHV genome encodes homologues to the four baculoviral per os infectivity factors (p74 [pif-0], pif-1, pif-2, and pif-3). The DNA polymerase encoded by GpSGHV is of type B and appears to be phylogenetically distant from all DNA polymerases encoded by large double-stranded DNA viruses. The majority of the remaining ORFs could not be assigned by sequence comparison. Furthermore, no homologues to DNA-dependent RNA polymerase subunits were detected. Taken together, these data indicate that GpSGHV is the prototype member of a novel group of insect viruses. PMID:18272583

  20. 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.

  1. Large-scale structure observables in general relativity

    NASA Astrophysics Data System (ADS)

    Jeong, Donghui; Schmidt, Fabian

    2015-02-01

    We review recent studies that rigorously define several key observables of the large-scale structure of the Universe in a general relativistic context. Specifically, we consider (i) redshift perturbation of cosmic clock events; (ii) distortion of cosmic rulers, including weak lensing shear and magnification; and (iii) observed number density of tracers of the large-scale structure. We provide covariant and gauge-invariant expressions of these observables. Our expressions are given for a linearly perturbed flat Friedmann-Robertson-Walker metric including scalar, vector, and tensor metric perturbations. While we restrict ourselves to linear order in perturbation theory, the approach can be straightforwardly generalized to higher order.

  2. Circular polarization of twilight.

    NASA Technical Reports Server (NTRS)

    Angel, J. R. P.; Illing, R.; Martin, P. G.

    1972-01-01

    Review of observations of circular polarization of twilight performed with a polarimeter which uses an electronically switched Pockels cell operated as a reversible quarter-wave plate to convert circular into linear polarization. The latter was then analyzed by a Wollaston prism followed by two gallium-arsenide photomultipliers. The discovery of a definite natural circular polarization at twilight does suggest that, with increased observation precision, measurements of the small daylight component are possible. These could give useful information about particles in the atmosphere and be valuable in studies of meteorology and air pollution.

  3. Observation of a Warped Helical Spin Texture in Bi2Se3 from Circular Dichroism Angle-Resolved Photoemission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Y. H.; Hsieh, D.; Pilon, D.; Fu, L.; Gardner, D. R.; Lee, Y. S.; Gedik, N.

    2011-11-01

    A differential coupling of topological surface states to left- versus right-circularly polarized light is the basis of many optospintronics applications of topological insulators. Here we report direct evidence of circular dichroism from the surface states of Bi2Se3 using laser-based time-of-flight angle-resolved photoemission spectroscopy. By employing a novel sample rotational analysis, we resolve unusual modulations in the circular dichroism photoemission pattern as a function of both energy and momentum, which perfectly mimic the predicted but hitherto unobserved three-dimensional warped spin texture of the surface states. By developing a microscopic theory of photoemission from topological surface states, we show that this correlation is a natural consequence of spin-orbit coupling. These results suggest that our technique may be a powerful probe of the spin texture of spin-orbit coupled materials in general.

  4. Observations of the Large Magellanic Cloud with Fermi

    Microsoft Academic Search

    M. Ackermann; M. Ajello; W. B. Atwood; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; B. M. Baughman; K. Bechtol; R. Bellazzini; B. Berenji; R. D. Blandford; E. D. Bloom; E. Bonamente; A. W. Borgland; J. Bregeon; A. Brez; M. Brigida; P. Bruel; T. H. Burnett; S. Buson; G. A. Caliandro; R. A. Cameron; P. A. Caraveo; J. M. Casandjian; C. Cecchi; Ö. Çelik; A. Chekhtman; C. C. Cheung; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; L. R. Cominsky; J. Conrad; S. Cutini; C. D. Dermer; A. de Angelis; F. de Palma; S. W. Digel; E. Do Couto E. Silva; P. S. Drell; R. Dubois; D. Dumora; C. Farnier; C. Favuzzi; S. J. Fegan; W. B. Focke; P. Fortin; M. Frailis; Y. Fukazawa; P. Fusco; F. Gargano; D. Gasparrini; N. Gehrels; S. Germani; G. Giavitto; B. Giebels; N. Giglietto; F. Giordano; T. Glanzman; G. Godfrey; E. V. Gotthelf; I. A. Grenier; M.-H. Grondin; J. E. Grove; L. Guillemot; S. Guiriec; Y. Hanabata; A. K. Harding; M. Hayashida; E. Hays; D. Horan; R. E. Hughes; M. S. Jackson; P. Jean; G. Jóhannesson; A. S. Johnson; R. P. Johnson; T. J. Johnson; W. N. Johnson; T. Kamae; H. Katagiri; J. Kataoka; N. Kawai; M. Kerr; J. Knödlseder; M. L. Kocian; M. Kuss; J. Lande; L. Latronico; M. Lemoine-Goumard; F. Longo; F. Loparco; B. Lott; M. N. Lovellette; P. Lubrano; G. M. Madejski; A. Makeev; F. Marshall; P. Martin; M. N. Mazziotta; W. McConville; J. E. McEnery; C. Meurer; P. F. Michelson; W. Mitthumsiri; T. Mizuno; A. A. Moiseev; C. Monte; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Murgia; P. L. Nolan; J. P. Norris; E. Nuss; T. Ohsugi; N. Omodei; E. Orlando; J. F. Ormes; D. Paneque; D. Parent; V. Pelassa; M. Pepe; M. Pesce-Rollins; F. Piron; T. A. Porter; S. Rainò; R. Rando; M. Razzano; A. Reimer; O. Reimer; T. Reposeur; S. Ritz; A. Y. Rodriguez; R. W. Romani; M. Roth; F. Ryde; H. F.-W. Sadrozinski; D. Sanchez; A. Sander; P. M. Saz Parkinson; J. D. Scargle; A. Sellerholm; C. Sgrò; E. J. Siskind; D. A. Smith; P. D. Smith; G. Spandre; P. Spinelli; J.-L. Starck; M. S. Strickman; A. W. Strong; D. J. Suson; H. Tajima; H. Takahashi; T. Tanaka; J. B. Thayer; J. G. Thayer; D. J. Thompson; L. Tibaldo; D. F. Torres; G. Tosti; A. Tramacere; Y. Uchiyama; T. L. Usher; V. Vasileiou; C. Venter; N. Vilchez; V. Vitale; A. P. Waite; P. Wang; P. Weltevrede; B. L. Winer; K. S. Wood; T. Ylinen; M. Ziegler

    2010-01-01

    Context. The Large Magellanic Cloud (LMC) is to date the only normal external galaxy that has been detected in high-energy gamma rays. High-energy gamma rays trace particle acceleration processes and gamma-ray observations allow the nature and sites of acceleration to be studied. Aims: We characterise the distribution and sources of cosmic rays in the LMC from analysis of gamma-ray observations.

  5. Large deployable reflectors for telecom and earth observation applications

    NASA Astrophysics Data System (ADS)

    Scialino, L.; Ihle, A.; Migliorelli, M.; Gatti, N.; Datashvili, L.; '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.

  6. Gamma-ray Sky Observed with Fermi Large Area Telescope

    E-print Network

    Yamamoto, Hirosuke

    Gamma-ray Sky Observed with Fermi Large Area Telescope RESCEU Symposium on Astroparticle Physics) Measure the photon direction Identification of the gamma-ray shower 36 planes of Si strip detectors (228 m) Calorimeter(CAL) Measure the photon energy Image the gamma-ray shower CsI(Tl) crystals in 8 layers. Anticoinc

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

    PubMed

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

    2015-06-16

    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

  8. Observational signatures of modified gravity on ultra-large scales

    E-print Network

    Baker, Tessa

    2015-01-01

    Extremely large surveys with future experiments like Euclid and the SKA will soon allow us to access perturbation modes close to the Hubble scale, with wavenumbers $k \\sim {\\cal H}$. If a modified gravity theory is responsible for cosmic acceleration, the Hubble scale is a natural regime for deviations from General Relativity (GR) to become manifest. The majority of studies to date have concentrated on the consequences of alternative gravity theories for the subhorizon, quasi-static regime, however. We investigate how modifications to the gravitational field equations affect perturbations around the Hubble scale, and how this translates into deviations of ultra large-scale relativistic observables from their GR behaviour. Adopting a model-independent ethos that relies only on the broad physical properties of gravity theories, we find that the deviations of the observables are small unless modifications to GR are drastic. The angular dependence and redshift evolution of the deviations is highly parameterisatio...

  9. FAST satellite observations of large-amplitude solitary structures

    Microsoft Academic Search

    R. E. Ergun; C. W. Carlson; J. P. McFadden; F. S. Mozer; G. T. Delory; W. Peria; C. C. Chaston; M. Temerin; I. Roth; L. Muschietti; R. Elphic; R. Strangeway; R. Pfaff; C. A. Cattell; D. Klumpar; E. Shelley; W. Peterson; E. Moebius; L. Kistler

    1998-01-01

    We report observations of ``fast solitary waves'' that are ubiquitous in downward current regions of the mid-altitude auroral zone. The single-period structures have large amplitudes (up to 2.5 V\\/m), travel much faster than the ion acoustic speed, carry substantial potentials (up to ~100 Volts), and are associated with strong modulations of energetic electron fluxes. The amplitude and speed of the

  10. Midlatitude lidar observations of large sporadic sodium layers

    Microsoft Academic Search

    Daniel C. Senft; Richard L. Collins; Chester S. Gardner

    1989-01-01

    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°N, 88°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⁻¹ before dissipating between 94 and 96

  11. Fermi Large Area Telescope Observations of the Vela Pulsar

    Microsoft Academic Search

    A. A. Abdo; M. Ackermann; W. B. Atwood; R. Bagagli; L. Baldini; J. Ballet; D. L. Band; G. Barbiellini; M. G. Baring; J. Bartelt; D. Bastieri; B. M. Baughman; K. Bechtol; F. Bellardi; R. Bellazzini; B. Berenji; D. Bisello; R. D. Blandford; E. D. Bloom; J. R. Bogart; E. Bonamente; A. W. Borgland; A. Bouvier; J. Bregeon; A. Brez; M. Brigida; P. Bruel; T. H. Burnett; G. A. Caliandro; R. A. Cameron; F. Camilo; P. A. Caraveo; J. M. Casandjian; M. Ceccanti; C. Cecchi; E. Charles; A. Chekhtman; C. C. Cheung; J. Chiang; S. Ciprini; R. Claus; I. Cognard; J. Cohen-Tanugi; L. R. Cominsky; J. Conrad; R. Corbet; L. Corucci; S. Cutini; D. S. Davis; M. DeKlotz; C. D. Dermer; A. de Angelis; F. de Palma; S. W. Digel; M. Dormody; E. do Couto e. Silva; P. S. Drell; R. Dubois; D. Dumora; C. Espinoza; C. Farnier; C. Favuzzi; D. L. Flath; P. Fleury; W. B. Focke; M. Frailis; P. C. C. Freire; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Gehrels; S. Germani; R. Giannitrapani; B. Giebels; N. Giglietto; F. Giordano; T. Glanzman; G. Godfrey; E. V. Gotthelf; I. A. Grenier; M.-H. Grondin; J. E. Grove; L. Guillemot; S. Guiriec; G. Haller; A. K. Harding; P. A. Hart; R. C. Hartman; E. Hays; G. Hobbs; R. E. Hughes; G. Jóhannesson; A. S. Johnson; R. P. Johnson; T. J. Johnson; W. N. Johnson; S. Johnston; T. Kamae; G. Kanbach; V. M. Kaspi; H. Katagiri; J. Kataoka; A. Kavelaars; N. Kawai; H. Kelly; M. Kerr; B. Kiziltan; W. Klamra; J. Knödlseder; M. Kramer; F. Kuehn; M. Kuss; J. Lande; D. Landriu; L. Latronico; B. Lee; S.-H. Lee; M. Lemoine-Goumard; M. Livingstone; F. Longo; F. Loparco; B. Lott; M. N. Lovellette; P. Lubrano; A. G. Lyne; G. M. Madejski; A. Makeev; R. N. Manchester; B. Marangelli; M. Marelli; M. N. Mazziotta; J. E. McEnery; S. McGlynn; M. A. McLaughlin; N. Menon; C. Meurer; P. F. Michelson; T. Mineo; N. Mirizzi; W. Mitthumsiri; T. Mizuno; A. A. Moiseev; M. Mongelli; C. Monte; M. E. Monzani; E. Moretti; A. Morselli; I. V. Moskalenko; S. Murgia; T. Nakamori; P. L. Nolan; A. Noutsos; E. Nuss; T. Ohsugi; N. Omodei; E. Orlando; J. F. Ormes; M. Ozaki; A. Paccagnella; D. Paneque; J. H. Panetta; D. Parent; M. Pearce; M. Pepe; M. Perchiazzi; M. Pesce-Rollins; L. Pieri; M. Pinchera; F. Piron; T. A. Porter; S. Rainò; R. Rando; S. M. Ransom; E. Rapposelli; M. Razzano; A. Reimer; O. Reimer; T. Reposeur; L. C. Reyes; S. Ritz; L. S. Rochester; A. Y. Rodriguez; R. W. Romani; M. Roth; F. Ryde; A. Sacchetti; H. F.-W. Sadrozinski; N. Saggini; D. Sanchez; A. Sander; P. M. Saz Parkinson; K. N. Segal; A. Sellerholm; C. Sgrò; E. J. Siskind; D. A. Smith; P. D. Smith; G. Spandre; P. Spinelli; M. Stamatikos; J.-L. Starck; F. W. Stecker; T. E. Stephens; M. S. Strickman; A. W. Strong; D. J. Suson; H. Tajima; H. Takahashi; T. Takahashi; T. Tanaka; A. Tenze; J. B. Thayer; J. G. Thayer; G. Theureau; D. J. Thompson; S. E. Thorsett; L. Tibaldo; O. Tibolla; D. F. Torres; A. Tramacere; M. Turri; T. L. Usher; L. Vigiani; N. Vilchez; V. Vitale; A. P. Waite; P. Wang; K. Watters; P. Weltevrede; B. L. Winer; K. S. Wood; T. Ylinen; M. Ziegler

    2009-01-01

    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,

  12. Magnetospheric observation of large sub-auroral electric fields

    Microsoft Academic Search

    N. C. Maynard; T. L. Aggson; J. P. Heppner

    1980-01-01

    An example of large sub-auroral poleward electric fields, similar to those observed on OGO-6, S3-2 and AE-C (recently referred to as SAID) has been found in the magnetosphere near L = 4 and 2300 MLT using ISEE-1 electric field data. The event is located adjacent to and outside the plasmapause and occurs 1 1\\/2 hours into a substorm. The event

  13. Circular Mesa

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-538, 8 November 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a circular mesa in northeast Arabia Terra. The circularity suggests that this landform might be similar to other circular mesas, found elsewhere on Mars. In those other cases, the mesa was once a meteor impact crater. The crater was filled with sediment, the sediment was cemented to become rock, and later erosion removed all of the material surrounding the former crater, leaving it standing alone as a circular mesa. This image is located near 23.7oN, 319.0oW, and covers an area 3 km (1.9 mi) wide. The scene is illuminated by sunlight from the left.

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

    SciTech Connect

    Senft, D.C.; Collins, R.L.; Gardner, C.S. (Univ. of Illinois, Urbana (USA))

    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.

  15. 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.

  16. Hot-electron-driven enhancement of spin-lattice coupling in Gd and Tb 4f ferromagnets observed by femtosecond x-ray magnetic circular dichroism.

    PubMed

    Wietstruk, Marko; Melnikov, Alexey; Stamm, Christian; Kachel, Torsten; Pontius, Niko; Sultan, Muhammad; Gahl, Cornelius; Weinelt, Martin; Dürr, Hermann A; Bovensiepen, Uwe

    2011-03-25

    Femtosecond x-ray magnetic circular dichroism was used to study the time-dependent magnetic moment of 4f electrons in the ferromagnets Gd and Tb, which are known for their different spin-lattice coupling. We observe a two-step demagnetization with an ultrafast demagnetization time of 750 fs identical for both systems and slower times which differ sizeably with 40 ps for Gd and 8 ps for Tb. We conclude that spin-lattice coupling in the electronically excited state is enhanced up to 50 times compared to equilibrium. PMID:21517350

  17. Observation of large-amplitude magnetosonic waves at dipolarization fronts

    NASA Astrophysics Data System (ADS)

    Zhou, Meng; Ni, Binbin; Huang, Shiyong; Deng, Xiaohua; Ashour-Abdalla, Maha; Nishimura, Yukitoshi; Yuan, Zhigang; Pang, Ye; Li, Huimin

    2014-06-01

    Various plasma waves have been observed in the vicinity of dipolarization fronts (DFs) and the rarefaction regions behind them. It was suggested that these waves not only play crucial roles in regulating particle kinetics at the DFs but also may potentially affect the large-scale dynamics of the magnetotail. In this paper, we present the observations of large-amplitude electromagnetic waves at DFs that occurred during magnetospheric substorms. The DFs were embedded in either the tailward or earthward flows in the near-Earth magnetotail. The wave frequencies were near the local proton cyclotron frequency. The waves propagated at highly oblique angles with respect to the ambient magnetic field (~80°-100°). Their corresponding wavelengths were on the order of the local ion gyroradii. The major magnetic field fluctuations were along the background magnetic field, while the electric field fluctuations were predominantly perpendicular to the background magnetic field. The waves were compressional waves as there was an anticorrelation between the plasma density and the wave magnetic field strength. The electric potential associated with the waves reached to more than half of the electron temperature, indicating the waves are nonlinear. We suggest that the waves were magnetosonic or ion Bernstein mode waves driven by the ion ring distribution. The waves were able to provide significant anomalous resistivity at the front, with major contributions from the electric field fluctuations. The effects of these waves on the electron pitch angle scattering and energy diffusion are also discussed.

  18. Giant optical activity of planar chiral nanostructures and circularly-polarized light emission

    Microsoft Academic Search

    K. Konishi; M. Kuwata-Gonokami

    2009-01-01

    We demonstrated large optical activity in the zeroth-order transmission with metal and dielectric planar chiral nanogratings enhanced by surface-plasmon or waveguide resonances; and observed circularly-polarized emission from the semiconductor chiral nanogratings with quantum dots.

  19. Elliptic and circular wormholes

    E-print Network

    P. F. González-Díaz

    1993-06-25

    Two new exact analytical solutions of the euclidean Einstein equations for a minimal massless scalar field and negative cosmological constant have been obtained. These solutions are given in terms of Jacobian elliptic or circular functions, rather than hyperbolic functions, connect large asymptotic regions of maximally-symmetric anti-DeSitter metrics through a microscopic throat, and correspond to negative definite components of the Ricci tensor. Therefore, they describe wormhole-like changes of topology driven by nucleation of baby universes. The quantum state of such elliptic and circular wormholes or handles is discussed in the most interesting inner and asymptotic regions.

  20. Evaluation of forest fire models on a large observation database

    NASA Astrophysics Data System (ADS)

    Filippi, J. B.; Mallet, V.; Nader, B.

    2014-11-01

    This paper presents the evaluation of several fire propagation models using a large set of observed fires. The observation base is composed of 80 Mediterranean fire cases of different sizes, which come with the limited information available in an operational context (burned surface and approximative ignition point). Simulations for all cases are carried out with four different front velocity models. The results are compared with several error scoring methods applied to each of the 320 simulations. All tasks are performed in a fully automated manner, with simulations run as first guesses with no tuning for any of the models or cases. This approach leads to a wide range of simulation performance, including some of the bad simulation results to be expected in an operational context. Disregarding the quality of the input data, it is found that the models can be ranked based on their performance and that the most complex models outperform the more empirical ones. Data and source codes used for this paper are freely available to the community.

  1. Evaluation of forest fire models on a large observation database

    NASA Astrophysics Data System (ADS)

    Filippi, J.-B.; Mallet, V.; Nader, B.

    2014-05-01

    This paper presents the evaluation of several fire propagation models using a large set of observed fires. The observation base is composed of 80 Mediterranean fire cases of different sizes, which come with the limited information available in an operational context (burned surface and approximative ignition point). Simulations for all cases are carried out with 4 different front velocity models. The results are compared with several error scoring methods applied to each of the 320 simulations. All tasks are performed in a fully automated manner, with simulations ran as first guesses with no tuning for any of the models or cases. This approach leads a wide range of simulation performance, including some of the bad simulation results to be expected in an operational context. Regardless the quality of the input data, it is found that the models can be ranked based on their performance and that the most complex models outperform the more empirical ones. Data and source code used for this paper are freely available to the community.

  2. 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].

  3. The flux of large meteoroids observed with lunar impact monitoring

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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 km^2). 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 the 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 3.8×10^6 km^2 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 2.5×10^{-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].

  4. Observing Planetary Nebulae with JWST and Extremely Large Telescopes

    NASA Astrophysics Data System (ADS)

    Sahai, Raghvendra

    2015-01-01

    Most stars in the Universe that leave the main sequence in a Hubble time will end their lives evolving through the Planetary Nebula (PN) evolutionary phase. The heavy mass loss which occurs during the preceding AGB phase is important across astrophysics, dramatically changing the course of stellar evolution, dominantly contributing to the dust content of the interstellar medium, and influencing its chemical composition. The evolution from the AGB phase to the PN phases remains poorly understood, especially the dramatic transformation that occurs in the morphology of the mass-ejecta as AGB stars and their round circumstellar envelopes evolve into mostly PNe, the majority of which deviate strongly from spherical symmetry. In addition, although the PN [OIII] luminosity function (PNLF) has been used as a standard candle (on par with distance indicators such as Cepheids), we do not understand why it works. It has been argued that the resolution of these issues may be linked to binarity and associated processes such as mass transfer and common envelope evolution.Thus, understanding the formation and evolution of PNe is of wide astrophysical importance. PNe have long been known to emit across a very large span of wavelengths, from the radio to X-rays. Extensive use of space-based observatories at X-ray (Chandra/ XMM-Newton), optical (HST) and far-infrared (Spitzer, Herschel) wavelengths in recent years has produced significant new advances in our knowledge of these objects. Given the expected advent of the James Webb Space Telescope in the near future, and ground-based Extremely Large Telescope(s) somewhat later, this talk will focus on future high-angular-resolution, high-sensitivity observations at near and mid-IR wavelengths with these facilities that can help in addressing the major unsolved problems in the study of PNe.

  5. SPITZER SAGE Observations of Large Magellanic Cloud Planetary Nebulae

    E-print Network

    J. L. Hora; M. Cohen; R. G. Ellis; M. Meixner; R. D. Blum; W. B. Latter; B. A. Whitney; M. R. Meade; B. L. Babler; R. Indebetouw; K. Gordon; C. W. Engelbracht; B. -Q. For; M. Block; K. Misselt; U. Vijh; C. Leitherer

    2007-11-01

    We present IRAC and MIPS images and photometry of a sample of previously known planetary nebulae (PNe) from the SAGE survey of the Large Magellanic Cloud (LMC) performed with the Spitzer Space Telescope. Of the 233 known PNe in the survey field, 185 objects were detected in at least two of the IRAC bands, and 161 detected in the MIPS 24 micron images. Color-color and color-magnitude diagrams are presented using several combinations of IRAC, MIPS, and 2MASS magnitudes. The location of an individual PN in the color-color diagrams is seen to depend on the relative contributions of the spectral components which include molecular hydrogen, polycyclic aromatic hydrocarbons (PAHs), infrared forbidden line emission from the ionized gas, warm dust continuum, and emission directly from the central star. The sample of LMC PNe is compared to a number of Galactic PNe and found to not significantly differ in their position in color-color space. We also explore the potential value of IR PNe luminosity functions (LFs) in the LMC. IRAC LFs appear to follow the same functional form as the well-established [O III] LFs although there are several PNe with observed IR magnitudes brighter than the cut-offs in these LFs.

  6. Fermi Large Area Telescope Observations of the Vela Pulsar

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Atwood, W. B.; Bagagli, R.; Baldini, L.; Ballet, J.; Band, D. L.; Barbiellini, G.; Baring, M. G.; Bartelt, J.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellardi, F.; Bellazzini, R.; Berenji, B.; Bisello, D.; Blandford, R. D.; Bloom, E. D.; Bogart, J. R.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Caliandro, G. A.; Cameron, R. A.; Camilo, F.; Caraveo, P. A.; Casandjian, J. M.; Ceccanti, M.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cognard, I.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Corbet, R.; Corucci, L.; Cutini, S.; Davis, D. S.; DeKlotz, M.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Digel, S. W.; Dormody, M.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Espinoza, C.; Farnier, C.; Favuzzi, C.; Flath, D. L.; Fleury, P.; Focke, W. B.; Frailis, M.; Freire, P. C. C.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giannitrapani, R.; Giebels, B.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Gotthelf, E. V.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Haller, G.; Harding, A. K.; Hart, P. A.; Hartman, R. C.; Hays, E.; Hobbs, G.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Johnston, S.; Kamae, T.; Kanbach, G.; Kaspi, V. M.; Katagiri, H.; Kataoka, J.; Kavelaars, A.; Kawai, N.; Kelly, H.; Kerr, M.; Kiziltan, B.; Klamra, W.; Knödlseder, J.; Kramer, M.; Kuehn, F.; Kuss, M.; Lande, J.; Landriu, D.; Latronico, L.; Lee, B.; Lee, S.-H.; Lemoine-Goumard, M.; Livingstone, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Lyne, A. G.; Madejski, G. M.; Makeev, A.; Manchester, R. N.; Marangelli, B.; Marelli, M.; Mazziotta, M. N.; McEnery, J. E.; McGlynn, S.; McLaughlin, M. A.; Menon, N.; Meurer, C.; Michelson, P. F.; Mineo, T.; Mirizzi, N.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Mongelli, M.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nolan, P. L.; Noutsos, A.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paccagnella, A.; Paneque, D.; Panetta, J. H.; Parent, D.; Pearce, M.; Pepe, M.; Perchiazzi, M.; Pesce-Rollins, M.; Pieri, L.; Pinchera, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Ransom, S. M.; Rapposelli, E.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Reyes, L. C.; Ritz, S.; Rochester, L. S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Ryde, F.; Sacchetti, A.; Sadrozinski, H. F.-W.; Saggini, N.; Sanchez, D.; Sander, A.; Parkinson, P. M. Saz; Segal, K. N.; Sellerholm, A.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Stamatikos, M.; Starck, J.-L.; Stecker, F. W.; Stephens, T. E.; Strickman, M. S.; Strong, A. W.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Tenze, A.; Thayer, J. B.; Thayer, J. G.; Theureau, G.; Thompson, D. J.; Thorsett, S. E.; Tibaldo, L.; Tibolla, O.; Torres, D. F.; Tramacere, A.; Turri, M.; Usher, T. L.; Vigiani, L.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Watters, K.; Weltevrede, P.; Winer, B. L.; Wood, K. S.; Ylinen, T.; Ziegler, M.

    2009-05-01

    The Vela pulsar is the brightest persistent source in the GeV sky and thus is the traditional first target for new ?-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 ? = 1.51+0.05 -0.04 with an exponential cutoff at Ec = 2.9 ± 0.1 GeV. Spectral fits with generalized cutoffs of the form e^{-(E/E_c)^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.

  7. Circular RNA Is Expressed across the Eukaryotic Tree of Life

    PubMed Central

    Wang, Peter L.; Bao, Yun; Yee, Muh-Ching; Barrett, Steven P.; Hogan, Gregory J.; Olsen, Mari N.; Dinneny, José R.; Brown, Patrick O.; Salzman, Julia

    2014-01-01

    An unexpectedly large fraction of genes in metazoans (human, mouse, zebrafish, worm, fruit fly) express high levels of circularized RNAs containing canonical exons. Here we report that circular RNA isoforms are found in diverse species whose most recent common ancestor existed more than one billion years ago: fungi (Schizosaccharomyces pombe and Saccharomyces cerevisiae), a plant (Arabidopsis thaliana), and protists (Plasmodium falciparum and Dictyostelium discoideum). For all species studied to date, including those in this report, only a small fraction of the theoretically possible circular RNA isoforms from a given gene are actually observed. Unlike metazoans, Arabidopsis, D. discoideum, P. falciparum, S. cerevisiae, and S. pombe have very short introns (?100 nucleotides or shorter), yet they still produce circular RNAs. A minority of genes in S. pombe and P. falciparum have documented examples of canonical alternative splicing, making it unlikely that all circular RNAs are by-products of alternative splicing or ‘piggyback’ on signals used in alternative RNA processing. In S. pombe, the relative abundance of circular to linear transcript isoforms changed in a gene-specific pattern during nitrogen starvation. Circular RNA may be an ancient, conserved feature of eukaryotic gene expression programs. PMID:24609083

  8. Importance of C*-H based modes and large amplitude motion effects in vibrational circular dichroism spectra: the case of the chiral adduct of dimethyl fumarate and anthracene.

    PubMed

    Passarello, Marco; Abbate, Sergio; Longhi, Giovanna; Lepri, Susan; Ruzziconi, Renzo; Nicu, Valentin Paul

    2014-06-19

    The role played by the C*-H based modes (C* being the chiral carbon atom) and the large amplitude motions in the vibrational absorption (VA) and vibrational circular dichroism (VCD) spectra is investigated. The example of an adduct of dimethyl fumarate and anthracene, i.e., dimethyl-(+)-(11R,12R)-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylate, and two deuterated isotopomers thereof specially synthesized for this goal, are considered. By comparing the experimental and DFT calculated spectra of the undeuterated and deuterated species, we demonstrate that the C*-H bending, rocking, and stretching modes in the VA and VCD spectra are clearly identified in well defined spectroscopic features. Further, significant information about the conformer distribution is gathered by analyzing the VA and VCD data of both the fingerprint and the C-H stretching regions, with particular attention paid to the band shape data. Effects related to the large amplitude motions of the two methoxy moieties have been simulated by performing linear transit (LT) calculations, which consists of varying systematically the relative positions of the two methoxy moieties and calculating VCD spectra for the partially optimized structures obtained in this way. The LT method allows one to improve the quality of calculated spectra, as compared to experimental results, especially in regard to relative intensities and bandwidths. PMID:24840313

  9. Classification of Circular Features on Venus

    NASA Technical Reports Server (NTRS)

    Stofan, E. R.; Head, J. W.; Grieve, R. A. F.

    1985-01-01

    Among the unanswered questions concerning Venus are the age of its surface and the mechanisms of lithospheric heat transfer (conduction, plate recycling, and hot spot volcanism). If there is a large population of impact craters, then the surface is ancient and Venus is characterized by conduction like the Moon, and Mercury, rather than plate recycling and hot spot volcanism. Alternatively, if there is a large population of volcanic craters, then the surface is younger and other mechanisms of heat transfer likely dominate. Previous studies have emphasized various aspects of the observational, theoretical, experimental, and comparative planetological studies of cratering on Venus, and several have reached divergent opinions concerning the age of the Venus surface. A major source of uncertainty in previous studies is the possible inclusion of circular features of nonimpact (volcanic or tectonic) origin in the so called impact crater population. A classification scheme of circular features on Venus is developed in order to further distinguish their origin and distribution.

  10. Scattering of circularly polarized radiation

    SciTech Connect

    Tinoco, I. Jr.; Keller, D.

    1983-07-21

    The differential refraction and absorption of circularly polarized light was applied by Henry Eyring and co-workers to study the configuration and conformation of small molecules. The differential scattering as a function of angle of circularly polarized light can provide structural information about large scattering systems. We present the general equations relating circular differential scattering to the eigenfunctions of a scatter which is of arbitrary size relative to the wavelength of light. An equiv experiment is to measure the ellipticity of the scattered light when linearly polarized light is incident.

  11. 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.

  12. Experimental Observation of Large Chern numbers in Photonic Crystals

    E-print Network

    Skirlo, Scott A; Igarashi, Yuichi; Joannopoulos, John; Soljacic, Marin

    2015-01-01

    Despite great interest in the quantum anomalous Hall phase and its analogs, all experimental studies in electronic and bosonic systems have been limited to a Chern number of one. Here, we perform microwave transmission measurements in the bulk and at the edge of ferrimagnetic photonic crystals. Bandgaps with large Chern numbers of 2, 3 and 4 are clearly present in the experimental results which show excellent agreement with theory. These large Chern number bandgaps support multimode one-way edge waveguides and can be used for the construction of topological power splitters and combiners.

  13. Observations of large scale emission in the far infrared

    NASA Astrophysics Data System (ADS)

    Birtwell, N. C.; Clarke, A. R.; Marsden, P. L.; Reehal, J. S.; Smith, C. D.

    1983-06-01

    A balloon-borne far infrared spectrometer for the investigation of extended sources in the wavelength range 80 to 500 microns was flown in 1980 and 1982 from Texas. During both campaigns periodicities of many minutes were detected in the IR gradients. In 1982 clear evidence for the existence of large scale stratospheric emission exhibiting weak azimuthal gradients, but strong elevational gradients was found. The large angle scanning technique enables the spatial extent and variability of the stratospheric phenomena, which may be linked to the El Chichon, Mexico, volcanic eruption in April 1982 to be investigated.

  14. Impacts of Typhoons on the Kuroshio Large Meander: Observation Evidences

    E-print Network

    Sun, Liang; Fu, Yun-Fei

    2009-01-01

    The formation of the Kuroshio large meander in summer 2004 was investigated by using the cruise data, Argo profiles data, and satellite remote sensing data. We validated the point that cyclonic eddy contributes to the large meander. Besides, the impacts of typhoons on Kuroshio meanders were studied. From 29 July to 4 August, the typhoons stirred the ocean and upwelled the deep water, which enhanced the existed cyclonic eddy, and immediately made a drastic meander of the Kuroshio. Moreover, the unexpected typhoons in June 2004 also contributed to the initial meander at Tokara Strait. The result suggests an alternative meander mechanism of Kuroshio path via typhoon-eddy-Kuroshio interactions. It is argued that typhoons accompanied with cyclonic eddies, might play crucial roles in meanders of the Kuroshio. This will provide a more comprehensive understanding of the dynamics of the west boundary flows like the Kuroshio and the Gulf Stream, and will be useful in eddy-resolution models.

  15. Large Observed $v_2$ as a Signature for Deconfinement

    E-print Network

    W. A. Horowitz

    2006-02-01

    We present a new plot for representing RAA data that emphasizes the strong correlation between high-pt suppression and its elliptic anisotropy. We demonstrate that existing models cannot reproduce the centrality dependence of this correlation. Modification of a geometric energy loss model to include thermal absorption and stimulated emission can match the trend of the data, but requires dN/dy values inconsistent with the observed multiplicity. By including a small, outward-normal directed surface impulse opposing energy loss, $\\Delta pt \\hat{n}$, one can account for the centrality dependence of the observed Au+Au elliptic quench pattern. We also present predictions for Cu+Cu reactions.

  16. IRAS Observations of Large Optical Galaxies (Rice+, 1988)

    Microsoft Academic Search

    W. Rice; C. J. Lonsdale; B. T. Soifer; G. Neugebauer; E. L. Kopan; L. A. Lloyd; T. de Jong; H. J. Habing

    1995-01-01

    The catalogue reports the observations of 85 galaxies listed in RC2 with apparent blue light isophotal diameters (D25) greater than 8'; there are 83 corresponding maps (NGC 205 and M31 are in one field as are M81 and M82) listed in file \\

  17. Observation of very large electromagnetic dissociation cross sections

    Microsoft Academic Search

    John C. Hill; F. K. Wohn; D. D. Schwellenbach; A. R. Smith

    1991-01-01

    An electromagnetic dissociation (ED) cross section of 3.16+\\/-0.23 b was observed for 197Au(238U, X)196Au with 0.96 GeV\\/ nucleon 238U projectiles. The gross features of ED are reproduced in a Weizsäcker-Williams (WW) calculation, but the projectile charge dependence is weaker than expected from WW. WW calculations are extended to the regime of energies of the next generation of relativistic heavy-ion colliders.

  18. Large-scale convection patterns observed by DMSP

    SciTech Connect

    Rich, F.J. [Hanscom Air Force Base, Bedford, MA (United States)] [Hanscom Air Force Base, Bedford, MA (United States); Hairston, M. [Univ. of Texas, Dallas, TX (United States)] [Univ. of Texas, Dallas, TX (United States)

    1994-03-01

    The authors present a comprehensive compilation of the average distribution of the electrostatic potential across the high-latitude ionosphere. The averages are compiled from potentials along the satellite path calculated from thermal ion drift data from instrumentation on the Defense Meterological Satellite Program (DMSP) flights 8 and 9 satellites. Data were collected from the DMSP F8 satellite during the period September 1987 to December 1990 and from the DMSP F9 satellite during the period March 1988 to December 1990. The potential distributions are separated by geomagnetic position, season, and orientation of the interplanetary magnetic field (IMF), and then averages of the distributions are calculated. The average potential distributions clearly show the displacement of polar cap convection contours to the dusk or dawk flanks under the influence of the IMF B{sub y} component. The cross-cap potential decreases as IMF B{sub z} changes from southward to northward. The average distributions indicate that the development of more than two convection cells for northward IMF is either uncommon or nonexistent. For IMF B{sub z} > 0 and B{sub z} >{vert_bar}B{sub y}{vert_bar}, a distorted pattern is observed in the average potential distribution, not a four-cell pattern as some previous studies suggest it should be. For all orientations of the IMF, the convection reversal boundary at the poleward edge of the auroral zone is observed in the average distributions to be a rotational boundary. It is not a shear boundary as suggested by some previous investigations. On average, the Harang discontinuity (convection reversal in the auroral zone near midnight) is observed to exist weakly or not at all. When examining individual passes, a strong eastward flow is present sometimes in the region of the Harang discontinuity, especially on the poleward boundary, but not at all times as implied by the Heppner-Maynard model. 39 refs., 9 figs., 2 tabs.

  19. 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.

  20. The thermal phase of a large solar flare. [Skylab observations

    NASA Technical Reports Server (NTRS)

    Withbroe, G. L.

    1978-01-01

    EUV and X-ray observations are used to derive the differential emission measures, temperatures, densities, radiative and conductive cooling rates, and thermal energy content of a class 2B flare that occurred on September 7, 1973. The results of the analysis indicate that (1) most of the flare plasma was at temperatures between 3 and 10 million degrees; (2) the peak temperature decreased with time from about 8 million K to 5 million K over a period of 3.5 hours; (3) the differential emission measure steadily decreased with time at nearly all temperatures; (4) both radiation and conduction were important cooling mechanisms for the plasma at temperatures above 100,000 K; and (5) a substantial amount of energy, of the order of 3 x 10 to the 31st power ergs, was deposited in the flare loops after flare maximum. The empirically determined flare parameters are compared with similar parameters derived from a simple theoretical loop model.

  1. Photon-photon interactions as a source of cosmic microwave background circular polarization

    NASA Astrophysics Data System (ADS)

    Sawyer, R. F.

    2015-01-01

    Photon-photon interactions, as described with the standard Heisenberg-Euler interaction, can transform plane polarization of the CMB into circular polarization, in the period right after last scattering. We estimate the distribution of the resulting circular polarization parameters, as constrained by confining observations to very small angular regions of large plane polarization, and find results of the order of 1 0-9 for the Stokes parameter V in some of these regions.

  2. Normal-Mode Analysis of Circular DNA at the Base-Pair Level. 2. Large-Scale Configurational Transformation of a Naturally Curved Molecule

    Microsoft Academic Search

    Atsushi Matsumoto; Irwin Tobias; Wilma K. Olson

    2005-01-01

    Fine structural and energetic details embedded in the DNA base sequence, such as intrinsic curvature, are important to the packaging and processing of the genetic material. Here we investigate the internal dynamics of a 200 bp closed circular molecule with natural curvature using a newly developed normal-mode treatment of DNA in terms of neighboring base-pair \\

  3. The effects of large vibration amplitudes on the axisymmetric mode shapes and natural frequencies of clamped thin isotropic circular plates. Part I: iterative and explicit analytical solution for non-linear transverse vibrations

    NASA Astrophysics Data System (ADS)

    Haterbouch, M.; Benamar, R.

    2003-07-01

    The effects of large vibration amplitudes on the first two axisymmetric mode shapes of clamped thin isotropic circular plates are examined. The theoretical model based on Hamilton's principle and spectral analysis developed previously by Benamar et al. for clamped-clamped beams and fully clamped rectangular plates is adapted to the case of circular plates using a basis of Bessel's functions. The model effectively reduces the large-amplitude free vibration problem to the solution of a set of non-linear algebraic equations. Numerical results are given for the first and second axisymmetric non-linear mode shapes for a wide range of vibration amplitudes. For each value of the vibration amplitude considered, the corresponding contributions of the basic functions defining the non-linear transverse displacement function and the associated non-linear frequency are given. The non-linear frequencies associated to the fundamental non-linear mode shape predicted by the present model were compared with numerical results from the available published literature and a good agreement was found. The non-linear mode shapes exhibit higher bending stresses near to the clamped edge at large deflections, compared with those predicted by linear theory. In order to obtain explicit analytical solutions for the first two non-linear axisymmetric mode shapes of clamped circular plates, which are expected to be very useful in engineering applications and in further analytical developments, the improved version of the semi-analytical model developed by El Kadiri et al. for beams and rectangular plates, has been adapted to the case of clamped circular plates, leading to explicit expressions for the higher basic function contributions, which are shown to be in a good agreement with the iterative solutions, for maximum non-dimensional vibration amplitude values of 0.5 and 0.44 for the first and second axisymmetric non-linear mode shapes, respectively.

  4. 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; Džafi?, 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 ?-lactoglobulin (?-LG) and ?-casein (?-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 ?-LG show a decrease around 1634 cm -1, suggesting a decrease of ?-sheet structure in the course of hydrolysis. Similarly, the intensity around the 1654 cm -1 band decreases for ?-CN digested by trypsin, indicating a reduction in the ?-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 ?-LG and ?-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.

  5. Circular polarization ratio characteristics of impact craters from Mini-RF observations and implications for ice detection at the polar regions of the Moon

    NASA Astrophysics Data System (ADS)

    Fa, Wenzhe; Cai, Yuzhen

    2013-08-01

    In an attempt to reduce the ambiguity on radar detection of water ice at the permanently shadowed regions near the lunar poles, radar echo strength and circular polarization ratio (CPR) of impact craters are analyzed using the Miniature Radio Frequency (Mini-RF) radar data from the Lunar Reconnaissance Orbiter mission. Eight typical craters, among over 70 craters, are selected and classified into four categories based on their locations and CPR characteristics: polar anomalous, polar fresh, nonpolar anomalous, and nonpolar fresh. The influences on CPR caused by surface slope, rocks, and dielectric constant are analyzed quantitatively using high-resolution topography data and optical images. A two-component mixed model for CPR that consists of a normal surface and a rocky surface is developed to study the effect of rocks that are perched on lunar surface and buried in regolith. Our analyses show that inner wall of a typical bowl-shaped crater can give rise to a change of about 30° in local incidence angle of radar wave, which can further result in a CPR difference of about 0.2. There is a strong correlation between Mini-RF CPR and rock abundance that is obtained from high-resolution optical images, and predictions from the two-component mixed model match well with the observed CPRs and the estimated rock abundances. Statistical results show that there is almost no apparent difference in CPR characteristics between the polar and nonpolar anomalous craters, or between the polar and nonpolar fresh craters. The enhanced CPR in the interior of anomalous craters is most probably caused by rocks that are perched on lunar surface or buried in regolith, instead of ice deposits as suggested in previous studies.

  6. Observation of very large and steep internal waves of elevation near the Massachusetts coast

    E-print Network

    Pineda, Jesús

    Observation of very large and steep internal waves of elevation near the Massachusetts coast Oceanography: Physical: Internal and inertial waves; 4219 Oceanography: General: Continental shelf processes and dynamics. Citation: Scotti, A., and J. Pineda (2004), Observation of very large and steep internal waves

  7. Model study of soft x-ray spectroscopy techniques for observing magnetic circular dichroism in buried SmCo magnetic films

    Microsoft Academic Search

    S. Itza-Ortiz; D. L. Ederer; T. M. Schuler; N. Ruzycki; J. Samuel Jiang; S. D. Bader

    2003-01-01

    X-ray emission and absorption spectroscopy (XES and XAS, respectively) are important and powerful techniques for determining the electronic properties of materials. Both are used to study magnetic circular dichroism (MCD) which is especially useful for analyzing the magnetic properties of materials. We present XAS and XES measurements and a MCD model study of two thin film layered samples containing SmCo

  8. Circular A-110 CIRCULAR A-110

    E-print Network

    Weston, Ken

    , hospitals, and other non-profit organizations. 2. Authority. Circular A-110 is issued under the authority and institutions of higher education, hospitals, and other non-profit organizations are set forth in this Circular for Grants and Agreements With Institutions of Higher Education, Hospitals, and Other Non-Profit

  9. Asteroids and Comets: the Prospect for Observations with a Large Millimetre Array

    E-print Network

    Demoulin, Pascal

    Asteroids and Comets: the Prospect for Observations with a Large Millimetre Array Jacques Crovisier Observatoire de Paris­Meudon, F­92195 Meudon, France Abstract. Radio continuum observations of asteroids will review here the current status and future prospect of radio astronomical observations of asteroids

  10. Observation of low-energy electrons in the photoelectron energy distribution from strong-field ionization of naphthalene by circularly polarized pulses

    NASA Astrophysics Data System (ADS)

    Dimitrovski, D.; Maurer, J.; Stapelfeldt, H.; Madsen, L. B.

    2015-06-01

    In a joint experimental and theoretical study we reveal the presence of low-energy photoelectrons created by strong circularly polarized laser pulses for both 3D aligned and randomly oriented naphthalene molecules. The analysis within a semiclassical model highlights the essential role of the induced dipole of the molecular cation in the creation of these low-energy electrons. The detailed comparison of experiment and theory points to significant modification of the molecular orbital nodal planes in strong fields.

  11. Observation of Cosmic Ray Anisotropy with Large Area Air Shower Experiments

    Microsoft Academic Search

    A. Iyono; C. Noda; H. Matsumoto

    2008-01-01

    The Large Area Air Shower experiments have been observing extensive air showers at sea level, in large part of Japan. The data set obtained for more than 10 years are going to be analyzed in order to study isotropic and anisotropy nature of cosmic ray arrival directions. We compare our results with diffusive propagation model of galactic cosmic rays in

  12. Observation of a neutrino burst in coincidence with supernova 1987A in the Large Magellanic Cloud

    Microsoft Academic Search

    R. M. Bionta; G. Blewitt; C. B. Bratton; D. Casper; A. Ciocio; R. Claus; B. Cortez; M. Crouch; S. T. Dye; S. Errede; G. Foster; W. Gajewski; K. Ganezer; M. Goldhaber; T. Haines; T. Jones; D. Kielczewska; W. Kropp; J. Learned; J. LoSecco; J. Matthews; R. Miller; M. Mudan; L. Price; F. Reines; J. Schultz; S. Seidel; E. Shumard; D. Sinclair; H. Sobel; J. Stone; L. Sulak; R. Svoboda; G. Thornton; J. van der Velde; C. Wuest

    1987-01-01

    A burst of eight neutrino events a preceding the optical detection of the supernova in the Large Magellanic Cloud has been observed in a large underground water Cherenkov detector. The events span an interval of 6 s and have visible energies in the range 20-40 MeV.

  13. Observations of a Large-Amplitude Internal Wave Train and Its Reflection off a Steep Slope

    E-print Network

    Observations of a Large-Amplitude Internal Wave Train and Its Reflection off a Steep Slope DANIEL, short, and large- amplitude internal wave train off a steep slope are presented and interpreted the parameter space examined in previous laboratory and numerical experiments on internal solitary wave

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

    Microsoft Academic Search

    L. J. Landau

    1994-01-01

    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 inRv 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.

  15. Synthesis and two-dimensional electrophoretic analysis of mixed populations of circular and linear RNAs.

    PubMed

    Feldstein, P A; Levy, L; Randles, J W; Owens, R A

    1997-12-01

    Spontaneous cleavage of the less abundant form of tobacco ringspot virus satellite RNA is readily reversible. Capitalizing on earlier observations by Feldstein and Bruening that small 'mini-monomer' RNAs derived from this molecule and containing little more than covalently attached ribozyme and substrate cleavage products are able to efficiently circularize, we have constructed a series of self-circularizing RNAs of precisely known size. Mixtures of linear and circular RNAs synthesized in vitro and containing 225-1132 nt could be completely resolved using a novel two-dimensional denaturing polyacrylamide gel electrophoresis system. Similar analyses of a complex mixture of coconut cadang-cadang viroid RNAs revealed the presence of relatively large amounts of a previously undescribed 'fast-slow' heterodimeric RNA species in infected palms. Only a single DNA template is required to prepare each pair of circular and linear RNA markers. PMID:9365267

  16. 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...

  17. Pressure-forced seiches of large amplitude in inlets of the Balearic Islands 2. Observational study

    Microsoft Academic Search

    M. Garcies; D. Gomis; S. Monserrat

    1996-01-01

    In part 1 of this study, Gomis et al. [1993] proposed a possible mechanism for the generation of large-amplitude seiches observed in inlets of the Balearic Islands. In part 2 we revise the proposed mechanism in light of recent observations. These consist of simultaneous records of sea level\\/bottom pressure measured at three locations inside and outside Ciutadella inlet and atmospheric

  18. Follow-up Observations of Eclipsing Binary EROS 1017 in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Hong, K.-S.; Kang, Y.-W.

    2007-06-01

    We present the second follow-up observations of EROS 1017 located in the central bar of the Large Magellanic Cloud. We developed a program for identifying comparison stars in crowded area. Three comparison stars were selected by using the searching program. Observational errors are estimated to be 0.008 mag and 0.009 mag in B and V, respectively.

  19. Are large Trojan asteroids salty? An observational, theoretical, and experimental study

    E-print Network

    Glotch, Timothy D.

    Are large Trojan asteroids salty? An observational, theoretical, and experimental study Bin Yang a: Trojan asteroids Infrared observations Asteroids, surfaces a b s t r a c t With a total mass similar to the main asteroid belt, the jovian Trojan asteroids are a major feature in the Solar System. Based upon

  20. 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.

  1. 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.

  2. 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.

  3. Study of a prototypical convective boundary layer observed during BLLAST: contributions by large-scale forcings

    NASA Astrophysics Data System (ADS)

    Pietersen, H. P.; Vilà-Guerau de Arellano, J.; Augustin, P.; van de Boer, A.; de Coster, O.; Delbarre, H.; Durand, P.; Fourmentin, M.; Gioli, B.; Hartogensis, O.; Lohou, F.; Lothon, M.; Ouwersloot, H. G.; Pino, D.; Reuder, J.

    2015-04-01

    We study the influence of the large-scale atmospheric contribution to the dynamics of the convective boundary layer (CBL) in a situation observed during the Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST) field campaign. We employ two modeling approaches, the mixed-layer theory and large-eddy simulation (LES), with a complete data set of surface and upper-air atmospheric observations, to quantify the contributions of the advection of heat and moisture, and subsidence. We find that by only taking surface and entrainment fluxes into account, the boundary-layer height is overestimated by 70%. Constrained by surface and upper-air observations, we infer the large-scale vertical motions and horizontal advection of heat and moisture. Our findings show that subsidence has a clear diurnal pattern. Supported by the presence of a nearby mountain range, this pattern suggests that not only synoptic scales exert their influence on the boundary layer, but also mesoscale circulations. LES results show a satisfactory correspondence of the vertical structure of turbulent variables with observations. We also find that when large-scale advection and subsidence are included in the simulation, the values for turbulent kinetic energy are lower than without these large-scale forcings. We conclude that the prototypical CBL is a valid representation of the boundary-layer dynamics near regions characterized by complex topography and small-scale surface heterogeneity, provided that surface- and large-scale forcings are representative for the local boundary layer.

  4. An experimental investigation on the flow around a circular cylinder in the first critical subregion

    Microsoft Academic Search

    Hyun Jin Kim

    1986-01-01

    An experimental investigation has been carried out on the flow transitions around a smooth circular cylinder in the initial stage of the critical Reynolds number region, where drag coefficient starts to decrease. In this Reynolds number region, intermittent reattachment of the separated boundary layer was found, while only initial separation position excursion was observed in the subcritical region. Large spanwise

  5. Phase space structure of the hydrogen atom in a circularly polarized microwave field

    E-print Network

    Politècnica de Catalunya, Universitat

    Studies of the three body problem and, in particular, the Sun-Earth- Moon system, have stimulated the problem of the hydrogen atom interacting with a circularly polarized microwave field, modeled the interaction is large. Here we are interested in the mechanisms that explain this observation. We find

  6. 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. [INAF-Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania (Italy); Hora, J. L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St. MS-65, Cambridge, MA 02138-1516 (United States)

    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}.

  7. Observations of Large Magnetospheric Electric Fields During the Onset Phase of a Substorm

    Microsoft Academic Search

    T. L. Aggson; J. P. Heppner; N. C. Maynard

    1983-01-01

    A large (30-mV\\/m peak) impulsive westward electric field was observed in the mid- night, low latitude, dipole L = 7.5 region of the earth's magnetospheric tail at the onset of a large substorm. The measurements were made with the long, 179-m baseline, cylindrical electric field probes carried by ISEE 1. The electric field impulse was coincident with a sharp 60

  8. Is the Lambda CDM Model Consistent with Observations of Large-Scale Structure?

    E-print Network

    Eric Gawiser

    2000-05-24

    The claim that large-scale structure data independently prefers the Lambda Cold Dark Matter model is a myth. However, an updated compilation of large-scale structure observations cannot rule out Lambda CDM at 95% confidence. We explore the possibility of improving the model by adding Hot Dark Matter but the fit becomes worse; this allows us to set limits on the neutrino mass.

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

    NASA Astrophysics Data System (ADS)

    Zamudio-Bayer, V.; Hirsch, K.; Langenberg, A.; Kossick, M.; ?awicki, A.; Terasaki, A.; v. Issendorff, B.; Lau, J. T.

    2015-06-01

    The electronic structure and magnetic moments of free Mn 2+ and Mn 3+ 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 ?B are created by 3d5(6S) 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 ?B for Mn 2+ and 16 ?B for Mn 3+ , with no contribution of orbital angular momentum.

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

    PubMed

    Zamudio-Bayer, V; Hirsch, K; Langenberg, A; Kossick, M; ?awicki, A; Terasaki, A; V Issendorff, B; Lau, J T

    2015-06-21

    The electronic structure and magnetic moments of free Mn2 (+) and Mn3 (+) 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 ?B are created by 3d(5)((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 ?B for Mn2 (+) and 16 ?B for Mn3 (+), with no contribution of orbital angular momentum. PMID:26093553

  11. 2. Northwest circular bastion, seen from edge of southwest circular ...

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

    2. Northwest circular bastion, seen from edge of southwest circular bastion wall. Metal roof beams extend up to form peak. World War II gun installation at right. - Fort Hamilton, Northwest Circular Bastion, Rose Island, Newport, Newport County, RI

  12. RSFQ circular shift registers

    Microsoft Academic Search

    Cess A. Mancini; Nada Vukovic; Andrea M. Herr; Kris Gaj; Mark F. Bocko; Marc J. Feldman

    1997-01-01

    The circular shift register is a versatile building block for RSFQ digital circuits. It can be used for local memory and it is essential for the proposed implementation of residue number system arithmetic. It is surprising that the successful recurrent operation of such a shift register has never been reported m the RSFQ literature. Circular shift registers have a design

  13. 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. [Institute of Physics, University of Graz, Graz A-8010 (Austria); Lugaz, N. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Farrugia, C. J.; Galvin, A. B. [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 (United States); Davies, J. A.; Harrison, R. A.; Crothers, S. [RAL Space, Harwell Oxford, Didcot OX11 0QX (United Kingdom); Luhmann, J. G. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Zhang, T. L.; Baumjohann, W., E-mail: christian.moestl@uni-graz.at [Space Research Institute, Austrian Academy of Sciences, Graz A-8042 (Austria)

    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.

  14. Explanation of recent observations of very large electromagnetic dissociation cross sections

    Microsoft Academic Search

    John Norbury

    1993-01-01

    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

  15. Earth Observations for rapid response to large earthquakes Supervisors: Dr Zhenhong Li and Prof Trevor Hoey

    E-print Network

    Guo, Zaoyang

    Earth Observations for rapid response to large earthquakes Supervisors: Dr Zhenhong Li and Prof Trevor Hoey School of Geographical and Earth Sciences, University of Glasgow, UK Earthquakes, together of the earth system; they are messengers of the fundamental processes that shape the surface of the Earth

  16. ATLAS: Australia Telescope Large Area Survey: Deep Radio Observations of the CDFS-SWIRE field

    E-print Network

    Norris, Ray

    ATLAS: Australia Telescope Large Area Survey: Deep Radio Observations of the CDFS-SWIRE field 1/UDF The Australia Telescope Compact Array used to make the radio images in this paper. CDF-S SWIRE ESO CTIO Las. Overview · We are imaging the CDFS and ELAIS-S1 SWIRE fields at 20 cm. Combining radio data with other

  17. 1 Large electric field at the nightside plasmapause 2 observed by the Polar spacecraft

    E-print Network

    Mozer, Forrest S.

    observed by the Polar spacecraft 3 K.H. Kim,1 F. S. Mozer,2 D.H. Lee,1 and H. Jin1 4 Received 5 March 2010 Citation: Kim, K.H., F. S. Mozer, D.H. Lee, and H. Jin (2010), Large electric field at the nightside

  18. Fermi Large Area Telescope Observations of the Crab Pulsar And Nebula

    Microsoft Academic Search

    A. A. Abdo; M. Ackermann; M. Ajello; W. B. Atwood; M. Axelsson; L. Baldini; J. Ballet; G. Barbiellini; M. G. Baring; D. Bastieri; K. Bechtol; R. Bellazzini; B. Berenji; R. D. Blandford; E. D. Bloom; E. Bonamente; A. W. Borgland; J. Bregeon; A. Brez; M. Brigida; P. Bruel; T. H. Burnett; G. A. Caliandro; R. A. Cameron; F. Camilo; P. A. Caraveo; J. M. Casandjian; C. Cecchi; Ö. Çelik; A. Chekhtman; C. C. Cheung; J. Chiang; S. Ciprini; R. Claus; I. Cognard; J. Cohen-Tanugi; L. R. Cominsky; J. Conrad; C. D. Dermer; A. de Angelis; A. de Luca; F. de Palma; S. W. Digel; E. do Couto e. Silva; P. S. Drell; R. Dubois; D. Dumora; C. Espinoza; C. Farnier; C. Favuzzi; S. J. Fegan; E. C. Ferrara; W. B. Focke; M. Frailis; P. C. C. Freire; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Gehrels; S. Germani; G. Giavitto; B. Giebels; N. Giglietto; F. Giordano; T. Glanzman; G. Godfrey; I. A. Grenier; M.-H. Grondin; J. E. Grove; L. Guillemot; S. Guiriec; Y. Hanabata; A. K. Harding; M. Hayashida; E. Hays; R. E. Hughes; G. Jóhannesson; A. S. Johnson; R. P. Johnson; T. J. Johnson; W. N. Johnson; S. Johnston; T. Kamae; H. Katagiri; J. Kataoka; N. Kawai; M. Kerr; J. Knödlseder; M. L. Kocian; M. Kramer; F. Kuehn; M. Kuss; J. Lande; L. Latronico; S.-H. Lee; M. Lemoine-Goumard; F. Longo; F. Loparco; B. Lott; M. N. Lovellette; P. Lubrano; A. G. Lyne; A. Makeev; M. Marelli; M. N. Mazziotta; J. E. McEnery; C. Meurer; P. F. Michelson; W. Mitthumsiri; T. Mizuno; A. A. Moiseev; C. Monte; M. E. Monzani; E. Moretti; A. Morselli; I. V. Moskalenko; S. Murgia; T. Nakamori; P. L. Nolan; J. P. Norris; A. Noutsos; E. Nuss; T. Ohsugi; N. Omodei; E. Orlando; J. F. Ormes; M. Ozaki; D. Paneque; J. H. Panetta; D. Parent; V. Pelassa; M. Pepe; M. Pesce-Rollins; M. Pierbattista; F. Piron; T. A. Porter; S. Rainò; R. Rando; P. S. Ray; M. Razzano; A. Reimer; O. Reimer; T. Reposeur; S. Ritz; L. S. Rochester; A. Y. Rodriguez; R. W. Romani; M. Roth; F. Ryde; H. F.-W. Sadrozinski; D. Sanchez; A. Sander; P. M. Saz Parkinson; J. D. Scargle; C. Sgrò; E. J. Siskind; D. A. Smith; P. D. Smith; G. Spandre; P. Spinelli; B. W. Stappers; M. S. Strickman; D. J. Suson; H. Tajima; H. Takahashi; T. Tanaka; J. B. Thayer; J. G. Thayer; G. Theureau; D. J. Thompson; S. E. Thorsett; L. Tibaldo; D. F. Torres; G. Tosti; A. Tramacere; Y. Uchiyama; T. L. Usher; A. Van Etten; V. Vasileiou; N. Vilchez; V. Vitale; A. P. Waite; E. Wallace; P. Wang; K. Watters; P. Weltevrede; B. L. Winer; K. S. Wood; T. Ylinen; M. Ziegler

    2010-01-01

    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 Nançay and Jodrell Bank radio telescopes shows two main peaks stable in phase with energy. The first gamma-ray peak leads the radio main pulse

  19. THE SPITZER c2d SURVEY OF LARGE, NEARBY, INTERSTELLAR CLOUDS. IV. LUPUS OBSERVED WITH MIPS

    E-print Network

    THE SPITZER c2d SURVEY OF LARGE, NEARBY, INTERSTELLAR CLOUDS. IV. LUPUS OBSERVED WITH MIPS Nicholas June 11 ABSTRACT We present maps of 7.78 deg2 of the Lupus molecular cloud complex at 24, 70, and 160 m cover three separate regions in Lupus, denoted I, III, and IV. We discuss the c2d pipeline and how our

  20. Large amplitude oscillation of an erupting filament as seen in EUV, H and microwave observations

    E-print Network

    Li, Yi

    Large amplitude oscillation of an erupting filament as seen in EUV, H and microwave observations H also identified the spatial displacement of the oscillation in 17 GHz microwave images from Nobeyama of filaments initiated by flare-associated disturbances (Ramsey & Smith 1966) may provide useful c 2007

  1. Particle Filtering for Large Dimensional State Spaces with Multimodal Observation Likelihoods

    Microsoft Academic Search

    Namrata Vaswani

    2008-01-01

    Abstract—We study efficient importance sampling techniques for particle filtering (PF) when either (a) the observation likelihood (OL) is frequently multimodal or heavy-tailed, or (b) the state space dimension is large or both. When the OL is multimodal, but the state transition pdf (STP) is narrow enough, the optimal importance density is usually unimodal. Under this assumption, many techniques have been

  2. Taming of the Slew: Optimization of the Large Scale X-Ray Surveys with Observing Strategy

    NASA Technical Reports Server (NTRS)

    Ptak, Andrew

    2010-01-01

    We will discuss simulations intended to address the relative efficiency of observing large areas with a slew observing strategy as opposed to pointing at fields individually. We will emphasize observing with the Wide Field X-ray Telescope (WFXT) but will also discuss optimization of observing strategy with the IXO Wide-Field Imager (WFI) and eRosita. The slew survey simulation is being implemented by translating the point direction along an arbitrary direction which addresses the impact of smoothing the telescope response during a given slew. However the simulation software is being designed to also allow the visibility of the sky to also be incorporated, in which case long-term observing plans could be developed to optimize the total sky coverage at a given depth and spatial resolution.

  3. 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.

  4. Large-amplitude electrostatic waves observed at a supercritical interplanetary shock

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    We present the first observations at an interplanetary shock of large-amplitude (> 100 mV/m pk-pk) solitary waves and large-amplitude (˜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.

  5. 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. PMID:25747366

  6. An Investigation of Circular Polarization in Star Formation Regions

    NASA Astrophysics Data System (ADS)

    Wolff, M.; Whitney, B.; Whittet, D.; Adamson, A.; Bailey, J.; Chrysostomou, A.; Hough, J.; Gledhill, T.; Lucas, P.; Clayton, G.

    Alignment of dust grains by magnetic fields, radiation, or stellar winds is expected to be a fairly common occurrence throughout the Galaxy and beyond. Aligned nonspherical grains produce polarization signatures at optical wavelengths by their dichroic scattering and extinction cross sections, and at far-IR wavelengths by dichroic emission mechanisms. The magnetic structure of galaxies and molecular clouds has been probed with optical and far-IR polarimetry. The primary polarization processes in these cases are differential extinction and emission, which are relatively straightforward to model. Such models can estimate magnetic field geometries, degree of alignment and degree of anisotropy. The scattering properties of aligned grains have been less well-studied because of the complexity of the problem; the scattering phase functions are complicated to calculate and are not amenable to simple analytic radiative transfer solutions. In sources where scattered light dominates the observed flux, such as edge-on pre-main sequence disks, protostars, and proto-planetary nebula observed at optical/near-IR wavelengths, alignment of the grains should have a significant effect on the polarization measurements. In fact, measurements of large circular polarization (CP) levels in some protostars, from 1-17%, imply the presence of aligned grains in these environments; randomly-oriented or spherical grains produce only very small amounts of circular polarization (usually much less than 1%), even in the most favorable scattering geometries. It is the goal of our presentation to explore this tantalizing potential utility of CP as a diagnostic of circumstellar grain properties and environments. Thus, we present radiative transfer calculations showing the polarization effects of scattering and absorption by aligned grains. The grain model consists of a size distribution of oblate or spinning prolate particles with varying degrees of alignment. To develop an understanding of the radiative transfer effects, we begin with the simple case of a spherical envelope illuminated by a central source with constant grain alignment axis throughout the envelope. Nonaligned grains produce no net polarization in such envelopes, while aligned grains produce substantial linear and circular polarization. The linear polarization results from the competing effects of differential extinction and scattering. The polarization varies strongly with optical depth, with scattering dominating at low optical depth and differential extinction dominating at high optical depth. The net, or integrated, circular polarization from the envelopes is zero; however, the circular polarization across the resolved nebula is large, reaching ± 50% in the ``diagonal'' regions of the nebula. Next we calculate axisymmetric models of protostellar envelopes, again with the simplifying case of constant grain alignment axis throughout the envelope. The polarization maps show differences from the case of nonaligned grains, especially in the disk mid-plane, where differential extinction of even the scattered light causes the polarization vectors to align perpendicular to the disk plane, in contrast to many observations. This suggests either that grains are not aligned in protostellar envelopes or that the magnetic field (the presumed alignment mechanism) is not aligned along the disk rotational axis throughout the envelope and disk. A definitive test of grain alignment could come from resolved circular polarization maps of protostars. Aligned grains produce large values of circular polarization across the cloud, up to ± 25%-40% in the models presented here, whereas nonaligned grains produce maximum polarizations of less than 1%. In objects with aligned grains, analysis of linear and circular polarization maps can probe magnetic geometries. Of additional interest are the large CP values previously observed in the OMC-1/IRc2 region of Orion. Although these data covered only the northerly region, they clearly indicate that the extent of the CP must reach beyond this limited region. It is clear t

  7. Circular Sound Wave Scattering Derivation for Acoustic Cloak Detection

    E-print Network

    Zhong, Siyang

    2012-01-01

    In this Letter we develop analytical formulations to describe sound scattering in lossless medium due to 2D circular wave incident on an acoustic cloak. A perfect acoustic cloak is reflectionless and can completely hide the cloaked object from any sound waves. However, the realization of a perfect acoustic cloak is difficult. Compared to plane wave, our analytic calculations show that circular wave from an annular line source generates distinct scattering patterns from an imperfect cloak design. Large modification in reflection directivities can be observed if the focal point of the incident wavefront is slightly customized. Hence, our work might find applications in acoustic cloak detection, which should have significant impact on cloak design and defense.

  8. To Circularize or Not to Circularize? -- Orbital Evolution of Satellite Galaxies

    E-print Network

    Yoshikazu Hashimoto; Yoko Funato; Junichiro Makino

    2002-08-26

    We investigated the orbital evolution of satellite galaxies using numerical simulations. It has been long believed that the orbit suffers circularization due to the dynamical friction from the galactic halo during orbital decay. This circularization was confirmed by numerous simulations where dynamical friction is added as external force. However, some of the resent N-body simulations demonstrated that circularization is much slower than expected from approximate calculations. We found that the dominant reason for this discrepancy is the assumption that Coulomb logarithm log Lambda is constant, which has been used in practically all recent calculations. Since the size of the satellite is relatively large, accurate determination of the outer cutoff radius is crucial to obtain good estimate for the dynamical friction. An excellent agreement between $N$-body simulations and approximate calculations was observed when the outer cutoff radius is taken to be the distance of the satellite to the center of the galaxy. When satellite is at the perigalacticon, the distance to the center is smaller and therefore log Lambda becomes smaller. As a result, the dynamical friction becomes less effective. We apply our result to the Large Magellanic Cloud. We found that the expected lifetime of the LMC is twice as long as that would be predicted with previous calculations. Previous study predicts that the LMC will merge into the Milky Way after 7 G years, while we found that the merging will take place after 14 G years from now. Our result suggests that generally satellites formed around a galaxy have longer lifetime than previous estimates.

  9. Model study of soft x-ray spectroscopy techniques for observing magnetic circular dichroism in buried SmCo magnetic films.

    SciTech Connect

    Itza-Ortiz, S.; Ederer, D. L.; Schuler, T. M.; Ruzycki, N.; Jiang, J. S.; Bader, S. D.; Materials Science Division; Tulane Univ.

    2003-02-15

    X-ray emission and absorption spectroscopy (XES and XAS, respectively) are important and powerful techniques for determining the electronic properties of materials. Both are used to study magnetic circular dichroism (MCD) which is especially useful for analyzing the magnetic properties of materials. We present XAS and XES measurements and a MCD model study of two thin film layered samples containing SmCo layers in order to report on the applicability of soft x-ray spectroscopic techniques to determine the composition, layer thickness, and electronic structure of such materials. Using a transmission by fluorescence attenuation (TFA) technique we determined the composition and thickness of the SmCo layer to be consistent with the intended composition and thickness. We also confirmed the thickness of the other layers by comparing the XES from the thin film with that of a bulk sample. We showed by a model study that TFA could be used to obtain MCD, and thus the anisotropy of the sample, for film thicknesses between about 400 and 800 {angstrom}.

  10. Model study of soft x-ray spectroscopy techniques for observing magnetic circular dichroism in buried SmCo magnetic films

    NASA Astrophysics Data System (ADS)

    Itza-Ortiz, S.; Ederer, D. L.; Schuler, T. M.; Ruzycki, N.; Jiang, J. Samuel; Bader, S. D.

    2003-02-01

    X-ray emission and absorption spectroscopy (XES and XAS, respectively) are important and powerful techniques for determining the electronic properties of materials. Both are used to study magnetic circular dichroism (MCD) which is especially useful for analyzing the magnetic properties of materials. We present XAS and XES measurements and a MCD model study of two thin film layered samples containing SmCo layers in order to report on the applicability of soft x-ray spectroscopic techniques to determine the composition, layer thickness, and electronic structure of such materials. Using a transmission by fluorescence attenuation (TFA) technique we determined the composition and thickness of the SmCo layer to be consistent with the intended composition and thickness. We also confirmed the thickness of the other layers by comparing the XES from the thin film with that of a bulk sample. We showed by a model study that TFA could be used to obtain MCD, and thus the anisotropy of the sample, for film thicknesses between about 400 and 800 Å.

  11. On the air motion in continental shallow cumulus clouds: large-eddy simulation versus radar observation

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Chandra, A.; Klein, S. A.

    2013-12-01

    Summertime observations for 13 years at Atmospheric Radiation Measurement Southern Great Plains (SGP) site are used to study air motion in non-precipitating fair-weather shallow cumulus clouds. A composite shallow cumulus case is constructed based on an ensemble of days with observed active shallow cumulus clouds. Large-scale forcing for this composite case is derived accordingly based on observation-constrained variational analysis and is used to drive the large-eddy simulation (LES), whose set-up is most suitable to make an apple-to-apple comparison with radar observation at the site. At the same time, a novel retrieval algorithm, which can remove the insects' contamination on radar reflectivity, is applied to millimeter cloud radar 10s observations to get vertical velocity of air motion in the shallow cumulus cloud ensembles. We then focus on the behavior of cloudy profiles with liquid water path greater than 80 g/m^2. This is done because we believe this portion of cloud makes a major contribution to the total mass flux and by so doing, the uncertainty is minimized in the comparison between observation and LES results. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-641597

  12. A large-sample atomic force microscope observing in both air and liquid.

    PubMed

    Fu, Xia; Zhang, Dongxian; Zhang, Haijun; Xie, Zhigang

    2011-11-01

    A large-sample atomic force microscope (AFM) that allows high resolution observation in both air and liquid has been developed. With a unique beam tracking method, laser beam is capable of reflecting off the same spot on the AFM cantilever throughout raster scan over the entire scan area, either operating in air or in liquid environment. Incorporating the stand-alone AFM probe unit with an automated large sample stage, wide-scan-range imaging can be realized with high resolution and slight distortion. In addition, an image stitching method is utilized to build a broad merged image with range up to millimeters while keeping nanometer order resolution. By using a large-volume liquid bath, large and massive sample can be observed in liquid with this AFM system. Several typical experiments have been carried out to demonstrate the imaging ability and stability of this AFM. Topographic structures of gold pattern on a glass substrate are scanned at two different places on the same specimen surface. The porosity of a sheet of filter paper is then characterized in both air and water. Finally, larger-area AFM image of anodic aluminum oxide template in oxalic acid is on spot obtained by merging several individually scanned images together. Experiments show that this AFM system can offer high resolution and wide range AFM images even for large samples with remarkable capabilities in various environments. PMID:21484944

  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. Explanation of recent observations of very large electromagnetic dissociation cross sections

    NASA Astrophysics Data System (ADS)

    Norbury, John W.

    1993-01-01

    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 nonperturbative approach to quantum electrodynamics.

  15. Observation of plasma flow at the magnetic island in the large helical device.

    PubMed

    Ida, K; Ohyabu, N; Morisaki, T; Nagayama, Y; Inagaki, S; Itoh, K; Liang, Y; Narihara, K; Kostrioukov, A Yu; Peterson, B J; Tanaka, K; Tokuzawa, T; Kawahata, K; Suzuki, H; Komori, A

    2002-01-01

    Radial profiles of ion temperature and plasma flow are measured at the n/m = 1/1 magnetic island produced by external perturbation coils in the Large Helical Device. The sheared poloidal flows and sheared radial electric field are observed at the boundaries of the magnetic island, because the poloidal flow vanishes inside the static magnetic island. When the width of the magnetic island becomes large, the flow along the magnetic flux surface inside the magnetic island appears around the O point in the direction which reduces the shear of the poloidal flow at the boundary of the magnetic island. PMID:11800959

  16. Observations and large-eddy simulations of the thermally driven cross-basin circulation in a small, closed basin

    NASA Astrophysics Data System (ADS)

    Lehner, Manuela

    Differential solar irradiation on opposing mountain sidewalls produces local temperature gradients. Flows across the valley or basin develop due to the ensuing horizontal pressure gradients, which are directed from the less irradiated and colder sidewall toward the more irradiated and warmer sidewall. These thermal flows are investigated for the small and almost circular basin of Arizona's Meteor Crater using observations and numerical simulations. Observations from the Meteor Crater show a pronounced cross-basin flow in the center of the crater basin under undisturbed conditions, which develops as an easterly flow in the morning when the sun is to the east and the west sidewall is more strongly irradiated, and which then shifts to a southerly direction around noon and eventually to a westerly direction in the evening. The direction of the cross-basin flow agrees with the direction of the cross-basin temperature and pressure gradients as the sun moves across the sky during the day. Large-eddy simulations for an idealized, rotationally symmetric basin produce a cross-basin circulation with a three-layer structure in the morning, that is, a near-surface southeasterly cross-basin flow topped by an opposing, northwesterly return flow and a secondary southeasterly flow near or above the top of the basin. Based on an analysis of the horizontal momentum and the thermodynamic balance equations, a different formation mechanism is identified for each layer, with each of the formation mechanisms being related to asymmetric irradiation. Additional simulations are run with a prescribed surface heat flux, which produces a spatially constant heat-flux gradient, and with varying background wind speeds and directions for different basin sizes. Results indicate that persistent cross-basin flows develop only in basins that are smaller than 5 km. Background winds induce a secondary circulation near the top of the basin, which interacts with the thermally driven circulation. The resulting wind field depends on the direction of the background winds with respect to the prescribed heat-flux gradient and on the stratification of the basin atmosphere.

  17. Planetary Rings: Circular and Non-circular

    NASA Astrophysics Data System (ADS)

    French, R. G.; Nicholson, P. D.; Colwell, J.; Marouf, E. A.; Rappaport, N. J.; Hedman, M. M.; McGhee, C.; Lonergan, K.; Sepersky, T.

    2011-12-01

    Although Saturn's rings appear at first glance to be axisymmetric, more precise measurements reveal that many of the gap edges and narrow ringlets within the rings are noncircular, a characteristic they share with the narrow uranian rings. A careful study of these features is of interest for several reasons: (i) resonantly-forced perturbations are believed to prevent the rings from spreading under the influence of collisions, (ii) unforced distortions, mostly eccentricities, can lead to estimates of the surface mass density and viscosity of the rings, and (iii) accurately-measured apsidal precession rates provide information on Saturn's zonal gravity harmonics. We present preliminary results from a comprehensive study of noncircular features in the Cassini Division and in the C ring. The data used in this study come from three Cassini experiments, and cover the period from May 2005 to September 2010. Over 120 stellar occultations have been observed by the Ultraviolet Imaging Spectrometer (UVIS) and by the Visual and Infrared Imaging Spectrometer (VIMS). In addition, we include 12 occultations of the spacecraft's radio Radio Science Subsystem (RSS) by the rings observed on Earth in May-September 2005. The simplest noncircular features can be modeled as inclined Keplerian ellipses, freely precessing under the influence of Saturn's oblate gravity field. In agreement with similar fits to the VIMS occultation data alone, we find that the inner edges of 7 of the 8 gaps within the Cassini Division are eccentric, with amplitudes ranging from 0.9 km to 28.3 km. In contrast, most of the outer gap edges are near-circular. We also find a rich assortment of normal modes on the edges of both ringlets and gaps. We have searched for modes with wavenumber m as high as 8, and find convincing evidence for modes with m = 0, 2, 3, 4 and 5, all with amplitudes of 1 km or greater. In some cases, as many as 3 or 4 normal modes coexist at a single edge with comparable amplitudes. Our fits also reveal the pervasive effects of the strong Mimas 2:1 inner Lindblad resonance (ILR), which has long been recognized to define the outer edge of the B ring. We find that almost all sharp-edged features in the Cassini Division exhibit a small but detectable m = 2 variation whose apoapse is locked to Mimas. The amplitudes of these distortions decrease with distance from the resonance, and conform to a simple analytical model for isolated test particles perturbed by the resonance. We confirm that the Colombo (or Titan) ringlet precesses at virtually the same rate as Titan's mean motion, 22.5770 deg d-1, with an apoapse oriented to within 4 deg of Titan's mean longitude. Both edges of this ringlet also exhibit what appear to be free normal modes, with m = 0 on the inner edge and m = 2, 3 and 4 on the outer edge. In contrast, the Maxwell ringlet is a freely precessing ellipse, and we see no evidence for additional normal modes on either edge. We also find clear evidence for normal modes on the edges of the Bond ringlet and Dawes gap.

  18. Large Scale Inhomogeneity Versus Source Evolution -- Can We Distinguish Them Observationally?

    E-print Network

    Nazeem Mustapha; Charles Hellaby; G. F. R. Ellis

    1998-08-28

    We reconsider the issue of proving large scale spatial homogeneity of the universe, given isotropic observations about us and the possibility of source evolution both in numbers and luminosities. Two theorems make precise the freedom available in constructing cosmological models that will fit the observations. They make quite clear that homogeneity cannot be proven without either a fully determinate theory of source evolution, or availability of distance measures that are independent of source evolution. We contrast this goal with the standard approach that assumes spatial homogeneity a priori, and determines source evolution functions on the basis of this assumption.

  19. Observing Abnormally Large Group Velocity at the Plasmonic Band Edge via a Universal Eigenvalue Analysis

    E-print Network

    Sha, Wei E I; Choy, Wallace C H; Chew, Weng Cho

    2015-01-01

    We developed a novel universal eigenvalue analysis for 2D arbitrary nanostructures comprising dispersive and lossy materials. The complex dispersion relation (or complex Bloch band structure) of a metallic grating is rigorously calculated by the proposed algorithm with the finite-difference implementation. The abnormally large group velocity is observed at a plasmonic band edge with a large attenuation constant. Interestingly, we found the abnormal group velocity is caused by the leaky (radiation) loss not by metallic absorption (Ohmic) loss. The periodically modulated surface of the grating significantly modifies the original dispersion relation of the semi-infinite dielectric-metal structure and induces the extraordinarily large group velocity, which is different from the near-zero group velocity at photonic band edge. The work is fundamentally important to the design of plasmonic nanostructures.

  20. Spectral Decay Characteristics in High Frequency Range of Observed Records from Crustal Large Earthquakes

    Microsoft Academic Search

    M. Tsurugi; T. Kagawa; K. Irikura

    2010-01-01

    Spectral decay characteristics in high frequency range of observed records from crustal large earthquakes occurred in Japan is examined. It is very important to make clear spectral decay characteristics in high frequency range for strong ground motion prediction. Target earthquakes are three events, the 2003 Miyagi-Ken Hokubu earthquake (Mw : 6.1), the 2005 Fukuoka-Ken Seiho-oki earthquake (Mw 6.6), and the

  1. Observation of Supernova Remnant IC 443 with the Fermi Large Area Telescope

    Microsoft Academic Search

    A. A. Abdo; M. Ackermann; M. Ajello; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; B. M. Baughman; K. Bechtol; R. Bellazzini; B. Berenji; R. D. Blandford; E. D. Bloom; E. Bonamente; A. W. Borgland; J. Bregeon; A. Brez; M. Brigida; P. Bruel; T. H. Burnett; S. Buson; G. A. Caliandro; R. A. Cameron; P. A. Caraveo; J. M. Casandjian; C. Cecchi; Ö. Çelik; A. Chekhtman; C. C. Cheung; J. Chiang; A. N. Cillis; S. Ciprini; R. Claus; J. Cohen-Tanugi; L. R. Cominsky; J. Conrad; S. Cutini; C. D. Dermer; A. de Angelis; F. de Palma; E. do Couto e. Silva; P. S. Drell; A. Drlica-Wagner; R. Dubois; D. Dumora; C. Farnier; C. Favuzzi; S. J. Fegan; W. B. Focke; P. Fortin; M. Frailis; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Gehrels; S. Germani; G. Giavitto; B. Giebels; N. Giglietto; F. Giordano; T. Glanzman; G. Godfrey; I. A. Grenier; M.-H. Grondin; J. E. Grove; L. Guillemot; S. Guiriec; Y. Hanabata; A. K. Harding; M. Hayashida; R. E. Hughes; M. S. Jackson; G. Jóhannesson; A. S. Johnson; T. J. Johnson; W. N. Johnson; T. Kamae; H. Katagiri; J. Kataoka; N. Kawai; M. Kerr; J. Knödlseder; M. L. Kocian; M. Kuss; J. Lande; L. Latronico; S.-H. Lee; M. Lemoine-Goumard; F. Longo; F. Loparco; B. Lott; M. N. Lovellette; P. Lubrano; G. M. Madejski; A. Makeev; M. N. Mazziotta; C. Meurer; P. F. Michelson; W. Mitthumsiri; A. A. Moiseev; C. Monte; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Murgia; T. Nakamori; P. L. Nolan; J. P. Norris; E. Nuss; T. Ohsugi; E. Orlando; J. F. Ormes; M. Ozaki; D. Paneque; J. H. Panetta; D. Parent; V. Pelassa; M. Pepe; M. Pesce-Rollins; F. Piron; T. A. Porter; S. Rainò; R. Rando; M. Razzano; A. Reimer; O. Reimer; T. Reposeur; L. S. Rochester; A. Y. Rodriguez; R. W. Romani; M. Roth; F. Ryde; H. F.-W. Sadrozinski; D. Sanchez; A. Sander; P. M. Saz Parkinson; J. D. Scargle; C. Sgrò; E. J. Siskind; D. A. Smith; P. D. Smith; G. Spandre; P. Spinelli; M. S. Strickman; A. W. Strong; D. J. Suson; H. Tajima; H. Takahashi; T. Takahashi; T. Tanaka; J. B. Thayer; J. G. Thayer; D. J. Thompson; L. Tibaldo; D. F. Torres; G. Tosti; A. Tramacere; Y. Uchiyama; T. L. Usher; A. Van Etten; V. Vasileiou; C. Venter; N. Vilchez; V. Vitale; A. P. Waite; P. Wang; B. L. Winer; K. S. Wood; T. Ylinen; M. Ziegler

    2010-01-01

    We report observation of the supernova remnant (SNR) IC 443 (G189.1+3.0) with the Fermi Gamma-ray Space Telescope Large Area Telescope (LAT) in the energy band between 200 MeV and 50 GeV. IC 443 is a shell-type SNR with mixed morphology located off the outer Galactic plane where high-energy emission has been detected in the X-ray, GeV and TeV gamma-ray bands.

  2. Survey of the ionospheric disturbances related with large seismic events in multi-satellite ionospheric observations

    NASA Astrophysics Data System (ADS)

    Ryu, K.; Chae, J.; Lee, E.; Kil, H.

    2013-12-01

    We survey the ionospheric disturbances in the plasma and electro-magnetic wave measurements during the simultaneous observation period of DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions), CHAMP (CHAllenging Minisatellite Payload) and DMSP(Defense Meteorological Satellite Program) missions. The multi-satellite observation around three large earthquakes that occurred between 2004 and 2005 were investigated. The observational evidences of the earth-quake precursory phenomena and the recent progress of physical modeling of the ionospheric disturbances caused by the coupling of the stressed rock, Earth surface charges, atmosphere, and ionosphere system are reviewed. Then, we focus on identifying the precursory disturbances from the well-studied plasma disturbances in the ionosphere, which are known to originate from various physical mechanism other than the seismic activities. Electron density/temperature, ion density/temperature, and electro-magnetic field/wave data measured by various instruments equipped in the satellites were analyzed in finding specific examples of anomaly caused by large seismic activities. Finally, the possibility of forecasting or predicting large earthquakes using the plasma measurements of LEO (low earth orbit) satellites will be discussed.

  3. 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 substantial promise for advancing our understanding of many unanswered questions of importance to the field of radiation oncology. PMID:25195986

  4. The genome of Oryctes rhinoceros nudivirus provides novel insight into the evolution of nuclear arthropod-specific large circular double-stranded DNA viruses

    Microsoft Academic Search

    Yongjie Wang; Olaf R. P. Bininda-Emonds; Monique M. van Oers; Just M. Vlak; Johannes A. Jehle

    2011-01-01

    The Oryctes rhinoceros nudivirus (OrNV) is a dsDNA virus with enveloped, rod-shaped virions. Its genome is 127,615 bp in size and contains 139 predicted\\u000a protein-coding open reading frames (ORFs). In-depth genome sequence comparisons revealed a varying number of shared gene homologues,\\u000a not only with other nudiviruses (NVs) and baculoviruses, but also with other arthropod-specific large dsDNA viruses, including\\u000a the so-called Monodon

  5. 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.

  6. 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.

  7. CIRCULAR RIBBON FLARES AND HOMOLOGOUS JETS

    SciTech Connect

    Wang Haimin; Liu Chang, E-mail: haimin.wang@njit.edu [Space Weather Research Laboratory, Center for Solar-Terrestrial Research, New Jersey Institute of Technology, University Heights, Newark, NJ 07102-1982 (United States)

    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.

  8. Tests of Quantum Gravity and Large Extra Dimensions Models Using High Energy Gamma Ray Observations

    E-print Network

    F. W. Stecker

    2003-06-09

    Observations of the multi-TeV spectra of the nearby BL Lac objects Mkn 421 and Mkn 501 exhibit the high energy cutoffs predicted to be the result of intergalactic annihilation interactions, primarily with IR photons having a flux level as determined by various astronomical observations. After correcting for such intergalactic absorption, these spectra can be explained within the framework of synchrotron self-Compton emission models. Stecker & Glashow have shown that the existence of this annihilation via electron-positron pair production puts strong constraints on Lorentz violation. Such constraints have important implications for quantum gravity models and large extra dimension models. We also discuss the implications of observations of high energy gamma-rays from the Crab Nebula on constraining quantum gravity models.

  9. Observation of the Crab Pulsar and Nebula with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Grondin, M.-H.; Lemoine-Goumard, M.; Loparco, F.; Mazziotta, M. N.

    2010-03-01

    The Crab Pulsar and Nebula are the remnants of the explosion of the supernova SN1054, which was observed by Chinese astronomers. Previously detected by EGRET, the Crab Pulsar and Nebula have been extensively observed in the gamma-ray energy band by the Large Area Telescope (LAT) onboard the Fermi satellite. The data collected by the LAT during its early operation stage have allowed a detailed measurement of the fluxes and of the energy spectra of both sources. The pulsar spectrum is consistent with the EGRET measurement in the region below 1 GeV and is well described by a power law with exponential cutoff at a few GeV. The nebula spectrum is well modeled by a sum of two power laws, identified respectively as the falling edge of the synchrotron and the rising edge of the inverse Compton components, and is in agreement with the observations from Earth-based telescopes.

  10. 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.

  11. 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 occurrence of large rain drops (D > 5 mm) in disdrometer observations, either stand alone or networked, generally representative and consistent with polarimetric radar observations? We first show from simulations that the concentration of large (D > 5 mm) rain drops (N(sub T5)) can be estimated from polarimetric observations of specific differential phase (K(sub dp)) and differential reflectivity (Z(sub dr)), N(sub T5)=F(K(sub dp),Z(sub dr)), or horizontal reflectivity (Z(sub h)) and Z(sub dr), N(sub T5)=(Z(sub h),Z(sub dr)). We assess the error associated with polarimetric retrieval of N(sub T5), including sensitivity to D(sub max) parameterization assumptions and measurement error in the radar simulations. Polarimetric measurements at S-band and C-band will then be used to retrieve estimates of N(sub T5) and compared to disdrometer estimates of N(sub T5). After careful consideration of retrieval error, we will check consistency between disdrometer and polarimetric radar estimates of N(sub T5) and the frequency of occurrence of large rain drops in a variety of precipitating regimes using data from NASA's Global Precipitation Measurement (GPM) Ground Validation (GV) program, including field campaigns such as MC3E (Oklahoma) and IFloodS (Iowa) and extended measurements over Huntsville, Alabama and NASA Wallops Flight Facility in coastal Virginia.

  12. Comparison Between Simulated and Observational Results of Galaxy Formation for Large Scale Structures

    NASA Astrophysics Data System (ADS)

    Li, G.; Scoville, N. Z.

    2009-10-01

    The Millennium simulation is the largest numerical simulation of how minor fluctuations in the density of the universe's dark matter distribution are amplified by gravity to develop into the large scale structures(LSS) and galaxy clusters seen today(Springel et al. 2005). Although the simulations have been compared with the astronomical observations of the local universe, the simulations have not been widely compared with high redshift, early universe observations. In our study we compare the simulation data(Wang et al. 2008; Guo et al. 2008(in preparation)) for the first time with observations from the COSMOS survey(Scoville et al. 2006). Three quantities are proposed to characterize the structures and the structures distribution, namely the percent area occupied by LSS at each redshift, the average area of LSS and the shapes as characterized by the square root of the area divided by the circumference. We calculate these quantities for both the observations and the simulations, and quantify discrepancies between the existing simulations and observations. In particular, the simulations exhibit earlier development of dense structures than is seen in the observational data.

  13. Challenging Large-scale Hydrological Simulations with Streamflow Observations: Response versus Persistence

    NASA Astrophysics Data System (ADS)

    Stahl, K.

    2014-12-01

    Land surface models and large-scale hydrological models are often used to study climate change impacts on hydrology at regional to global scales. These impacts are then presented as maps of change in specific runoff metrics that are relevant to basin management and water resources planning. Knowing the limits of model performance for the respective metrics of interest at different spatial and temporal scales is thus important, but often performance is only known for annual or long-term means. This contribution summarizes and reflects on the challenge of continental hydrological model simulations from the WATCH multi-model ensemble with distributed streamflow observations from small basins of reference networks in Europe. Characteristics of hydrological dynamics that were compared include spatial and temporal runoff persistence, high and low flows, and long-term trends and variability. Whereas common annual statistics between models and observations correlate well even if the amounts disagree, larger differences were found for metrics that focus on the dynamics of streamflow response and persistence. For example, models appear to respond comparably fast to precipitation, and as a consequence underestimate the duration of streamflow drought events. Investigating the general streamflow persistence in time and space, however, also showed large differences among the different models. Long-term trends in annual flow and annual weekly peak flow in Europe agreed on the large-scale patterns, but particularly seasonal trends and trends in extremes in regions with mixed observed runoff trends or in complex terrain revealed discrepancies to the observations even regarding the sign of the trend. Before the display of changes in hydrological characteristics related to response and persistence of flow situations, models should therefore always be tested specifically for their limits to represent such metrics.

  14. EXPANDED VERY LARGE ARRAY CONTINUUM OBSERVATIONS TOWARD HOT MOLECULAR CORE CANDIDATES

    SciTech Connect

    Hofner, P. [Physics Department, New Mexico Tech, 801 Leroy Pl., Socorro, NM 87801 (United States); Kurtz, S.; Loinard, L.; RodrIguez, L. F. [Centro de RadioastronomIa y Astrofisica, P.O. Box 3-72 Universidad Nacional Autonoma de Mexico, Morelia 58090 (Mexico); Ellingsen, S. P. [School of Mathematics and Physics, University of Tasmania, Private Bag 37, Hobart, Tasmania 7001 (Australia); Menten, K. M.; Wyrowski, F. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany); Araya, E. D. [Physics Department, Western Illinois University, 1 University Circle, Macomb, IL 61455 (United States); Cesaroni, R. [INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze (Italy)

    2011-09-20

    We have used the Expanded Very Large Array (EVLA) with two 1 GHz wide bands to obtain K-band (1.3 cm) continuum observations toward the following five hot molecular core candidates: IRAS 18151 - 1208, IRAS 18182 - 1433, IRAS 18345 - 0641, IRAS 18470 - 0044, and IRAS 19012 + 0536. The sources were selected from the 2002 list of Sridharan et al. and are characterized by high FIR luminosity, dense molecular and dust condensations, massive large-scale CO flows, and the absence of strong cm continuum emission. These properties are indicative of massive star-forming regions in an evolutionary phase prior to ultra- or hypercompact H II regions. We detect a total of 10 individual 1.3 cm continuum sources toward this sample, and derive in-band spectral indices between 19.3 and 25.5 GHz consistent with thermal free-free emission, for all sources except component A in IRAS 18182 - 1433, which has a negative spectral index indicative of synchrotron emission. We suggest that in most cases the 1.3 cm sources are due to shock-induced ionization, rather than direct photoionization by massive objects. The momentum rate present in these ionized flows is sufficient to drive the large-scale molecular flows. We discuss a number of morphological features supporting this hypothesis. The present observations demonstrate that the EVLA has sufficient sensitivity to study the regions near very young massive stars in the cm continuum.

  15. Very Large Array and Jansky Very Large Array Observations of the Compact Radio Sources in M8

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  16. Fermi Large Area Telescope Observations of Two Gamma-Ray Emission Components from the Quiescent Sun

    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.; 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.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; 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.; Digel, S. W.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Fortin, P.; Frailis, M.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grillo, L.; Guiriec, S.; Hadasch, D.; Hays, E.; Hughes, R. E.; Iafrate, G.; Jóhannesson, G.; Johnson, A. S.; Johnson, T. J.; Kamae, T.; Katagiri, H.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Lionetto, A. M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; 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.; Nakamori, T.; Naumann-Godo, M.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Pelassa, V.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Sadrozinski, H. F.-W.; Schalk, T. L.; Sgrò, C.; Share, G. H.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Strong, A. W.; Takahashi, H.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vilchez, N.; Vitale, V.; Vladimirov, A. E.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ziegler, M.

    2011-06-01

    We report the detection of high-energy ?-rays from the quiescent Sun with the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope (Fermi) during the first 18 months of the mission. These observations correspond to the recent period of low solar activity when the emission induced by cosmic rays (CRs) is brightest. For the first time, the high statistical significance of the observations allows clear separation of the two components: the point-like emission from the solar disk due to CR cascades in the solar atmosphere and extended emission from the inverse Compton (IC) scattering of CR electrons on solar photons in the heliosphere. The observed integral flux (>=100 MeV) from the solar disk is (4.6 ± 0.2[statistical error]+1.0 - 0.8[systematic error]) × 10-7 cm-2 s-1, which is ~7 times higher than predicted by the "nominal" model of Seckel et al. In contrast, the observed integral flux (>=100 MeV) of the extended emission from a region of 20° radius centered on the Sun, but excluding the disk itself, (6.8 ± 0.7[stat.]+0.5 - 0.4[syst.]) × 10-7 cm-2 s-1, along with the observed spectrum and the angular profile, is in good agreement with the theoretical predictions for the IC emission.

  17. EXPANDED VERY LARGE ARRAY NOVA PROJECT OBSERVATIONS OF THE CLASSICAL NOVA V1723 AQUILAE

    SciTech Connect

    Krauss, Miriam I.; Chomiuk, Laura; Rupen, Michael; Roy, Nirupam; Mioduszewski, Amy J., E-mail: mkrauss@nrao.edu, E-mail: lchomiuk@nrao.edu, E-mail: mrupen@nrao.edu, E-mail: nroy@nrao.edu [National Radio Astronomy Observatory, Socorro, NM 87801 (United States)

    2011-09-20

    We present radio light curves and spectra of the classical nova V1723 Aql obtained with the Expanded Very Large Array (EVLA). This is the first paper to showcase results from the EVLA Nova Project, which comprises a team of observers and theorists utilizing the greatly enhanced sensitivity and frequency coverage of EVLA radio observations, along with observations at other wavelengths, to reach a deeper understanding of the energetics, morphology, and temporal characteristics of nova explosions. Our observations of V1723 Aql span 1-37 GHz in frequency, and we report on data from 14 to 175 days following the time of the nova explosion. The broad frequency coverage and frequent monitoring show that the radio behavior of V1723 Aql does not follow the classic Hubble-flow model of homologous spherically expanding thermal ejecta. The spectra are always at least partially optically thin, and the flux rises on faster timescales than can be reproduced with linear expansion. Therefore, any description of the underlying physical processes must go beyond this simple picture. The unusual spectral properties and light curve evolution might be explained by multiple emitting regions or shocked material. Indeed, X-ray observations from Swift reveal that shocks are likely present.

  18. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF TWO GAMMA-RAY EMISSION COMPONENTS FROM THE QUIESCENT SUN

    SciTech Connect

    Abdo, A. A. [Center for Earth Observing and Space Research, College of Science, George Mason University, Fairfax, VA 22030 (United States); Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Borgland, A. W.; Buehler, R. [Department of Physics and SLAC National Accelerator Laboratory, W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305 (United States); Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d'Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D.; Buson, S. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bonamente, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Bouvier, A. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Brigida, M. [Dipartimento di Fisica 'M. Merlin' dell'Universita e del Politecnico di Bari, I-70126 Bari (Italy); Bruel, P. [Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Palaiseau (France); Caliandro, G. A., E-mail: imos@stanford.edu, E-mail: eorlando@stanford.edu, E-mail: brigida@ba.infn.it, E-mail: nico.giglietto@ba.infn.it [Institut de Ciencies de l'Espai (IEEC-CSIC), Campus UAB, 08193 Barcelona (Spain)

    2011-06-20

    We report the detection of high-energy {gamma}-rays from the quiescent Sun with the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope (Fermi) during the first 18 months of the mission. These observations correspond to the recent period of low solar activity when the emission induced by cosmic rays (CRs) is brightest. For the first time, the high statistical significance of the observations allows clear separation of the two components: the point-like emission from the solar disk due to CR cascades in the solar atmosphere and extended emission from the inverse Compton (IC) scattering of CR electrons on solar photons in the heliosphere. The observed integral flux ({>=}100 MeV) from the solar disk is (4.6 {+-} 0.2[statistical error]{sup +1.0}{sub -0.8}[systematic error]) x 10{sup -7} cm{sup -2} s{sup -1}, which is {approx}7 times higher than predicted by the 'nominal' model of Seckel et al. In contrast, the observed integral flux ({>=}100 MeV) of the extended emission from a region of 20 deg. radius centered on the Sun, but excluding the disk itself, (6.8 {+-} 0.7[stat.]{sup +0.5}{sub -0.4}[syst.]) x 10{sup -7} cm{sup -2} s{sup -1}, along with the observed spectrum and the angular profile, is in good agreement with the theoretical predictions for the IC emission.

  19. Expanded Very Large Array Nova Project Observations of the Classical NovaV1723 Aquilae

    NASA Technical Reports Server (NTRS)

    Krauss, Miriam I.; Chomiuk, Laura; Rupen, Michael; Roy, Nirupam; Mioduszewski, Amy J.; Sokoloski, J. L.; Nelson, Thomas; Mukai, Koji; Bode, M. F.; Eyres, S. P. S.; OBrien, T. J.

    2011-01-01

    We present radio light curves and spectra of the classical nova VI723 Aql obtained with the Expanded Very Large Array (EVLA). This is the first paper to showcase results from the EVLA Nova Project, which comprises a team of observers and theorists utilizing the greatly enhanced sensitivity and frequency coverage of EVLA radio observations, along with observations at other wavelengths, to reach a deeper understanding of the energetics, morphology, and temporal characteristics of nova explosions. Our observations of VI723 Aql span 1-37 GHz in frequency, and we report on data from 14 to 175 days following the time of the nova explosion. The broad frequency coverage and frequent monitoring show that the radio behavior of VI723 Aql does not follow the classic Hubble-flow model of homologous spherically expanding thermal ejecta. The spectra are always at least partially optically thin, and the flux rises on faster timescales than can be reproduced with linear expansion. Therefore, any description of the underlying physical processes must go beyond this simple picture. The unusual spectral properties and light curve evolution might be explained by multiple emitting regions or shocked material. Indeed, X-ray observations from Swift reveal that shocks are likely present.

  20. SWAP Observations of the Long-Term, Large-Scale Evolution of the EUV Solar Corona

    E-print Network

    Seaton, Daniel B; Shearer, Paul; Berghmans, David; Nicula, Bogdan

    2013-01-01

    The Sun Watcher with Active Pixels and Image Processing (SWAP) EUV solar telescope on board the Project for On-Board Autonomy 2 (PROBA2) spacecraft has been regularly observing the solar corona in a bandpass near 17.4 nm since February 2010. With a field-of-view of 54x54 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 (PSF) 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 persiste...

  1. CONTEMPORANEOUS VLBA 5 GHz OBSERVATIONS OF LARGE AREA TELESCOPE DETECTED BLAZARS

    SciTech Connect

    Linford, J. D.; Taylor, G. B. [Department of Physics and Astronomy, University of New Mexico, MSC07 4220, Albuquerque, NM 87131-0001 (United States); Romani, R. W. [Department of Physics, Stanford University, Stanford, CA 94305 (United States); Helmboldt, J. F. [Naval Research Laboratory, Code 7213, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Readhead, A. C. S.; Reeves, R.; Richards, J. L. [Astronomy Department, California Institute of Technology, Mail Code 247-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States)

    2012-01-10

    The radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed contemporaneously by the Very Long Baseline Array (VLBA). In total, 232 sources were observed with the VLBA. Ninety sources that were previously observed as part of the VLBA Imaging and Polarimetry Survey (VIPS) have been included in the sample, as well as 142 sources not found in VIPS. This very large, 5 GHz flux-limited sample of active galactic nuclei (AGNs) provides insights into the mechanism that produces strong {gamma}-ray emission. In particular, we see that {gamma}-ray emission is related to strong, uniform magnetic fields in the cores of the host AGN. Included in this sample are non-blazar AGNs such as 3C84, M82, and NGC 6251. For the blazars, the total VLBA radio flux density at 5 GHz correlates strongly with {gamma}-ray flux. The LAT BL Lac objects tend to be similar to the non-LAT BL Lac objects, but the LAT flat-spectrum radio quasars (FSRQs) are significantly different from the non-LAT FSRQs. Strong core polarization is significantly more common among the LAT sources, and core fractional polarization appears to increase during LAT detection.

  2. The Large Scale Cosmic-Ray Anisotropy as Observed with Milagro

    E-print Network

    A. A. Abdo; B. T. Allen; T. Aune; D. Berley; S. Casanova; C. Chen; B. L. Dingus; R. W. Ellsworth; L. Fleysher; R. Fleysher; M. M. Gonzalez; J. A. Goodman; C. M. Hoffman; B. Hopper; P. H. Hüntemeyer; B. E. Kolterman; C. P. Lansdell; J. T. Linnemann; J. E. McEnery; A. I. Mincer; P. Nemethy; D. Noyes; J. Pretz; J. M. Ryan; P. M. Saz Parkinson; A. Shoup; G. Sinnis; A. J. Smith; G. W. Sullivan; V. Vasileiou; G. P. Walker; D. A. Williams; G. B. Yodh

    2009-04-20

    Results are presented of a harmonic analysis of the large scale cosmic-ray anisotropy as observed by the Milagro observatory. We show a two-dimensional display of the sidereal anisotropy pro jections in right ascension generated by the fitting of three harmonics to 18 separate declination bands. The Milagro observatory is a water Cherenkov detector located in the Jemez mountains near Los Alamos, New Mexico. With a high duty cycle and large field-of-view, 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, the largest such data set in existence. We observe an anisotropy with a magnitude around 0.1% for cosmic rays with a median energy of 6 TeV. The dominant feature is a deficit region of depth (2.49 +/- 0.02 stat. +/- 0.09 sys.)x10^(-3) in the direction of the Galactic North Pole centered at 189 degrees right ascension. We observe a steady increase in the magnitude of the signal over seven years.

  3. The Large Aperture Gamma Ray Observatory as an Observational Alternative at High Altitude

    NASA Astrophysics Data System (ADS)

    Rosales, M.

    2011-10-01

    Although satellite observations have revealed some mysteries about the origin and location of cosmic rays at low energies, questions remain to be resolved in higher energy ranges (>1 GeV). However, the flow of particles at high energies is very low, large sensitive areas are necessary, so that the detection of secondary particles from observatories on the surface of the earth is a technically viable solution. While the Pierre Auger Observatory has such capacity given its 16000 m^2 of detectors, low height above sea level greatly reduces its detection capability. The Large Aperture Gamma Ray Observatory (LAGO) is an observational alternative that attempts to overcome this limitation. This project was started in 2005, placing water Cherenkov Detectors at high altitude. Observation sites have been selected with some basic requirements: altitude, academic and technical infrastructure, existence of a research group responsible for assembly and maintenance of the detectors and the analysis, visualization, divulgation and data storage. This paper presents the general status of the observatories of Sierra Negra-México, Chacaltaya-Bolívia, Marcapomacocha-Perú, Mérida-Venezuela and Bucaramanga-Colombia.

  4. Branching and Circular Features in High Dimensional Bei Wang, Brian Summa, Valerio Pascucci, and Mikael Vejdemo-Johansson

    E-print Network

    Utah, University of

    1 Branching and Circular Features in High Dimensional Data Bei Wang, Brian Summa, Valerio Pascucci Salt Lake City, UT 84112 USA May 30, 2011 Abstract: Large observations and simulations in scientific research give rise to high-dimensional data sets that present many challenges and opportunities in data

  5. Can the observed large scale magnetic fields be seeded by helical primordial fields?

    SciTech Connect

    Caprini, Chiara [IPhT, CEA-Saclay, CNRS, URA 2306, F-91191 Gif-sur-Yvette (France); Durrer, Ruth; Fenu, Elisa, E-mail: chiara.caprini@cea.fr, E-mail: ruth.durrer@unige.ch, E-mail: elisa.fenu@unige.ch [Département de Physique Théorique, Université de Genève, 24 quai Ernest Ansermet, CH–1211 Genève 4 (Switzerland)

    2009-11-01

    Gravitational wave production induces a strong constraint on the amplitude of a primordial magnetic field. It has been shown that the nucleosynthesis bound for a stochastic gravitational wave background implies that causally generated fields cannot have enough power on large scales to provide the seeds necessary for the observed magnetic fields in galaxies and clusters, even by the most optimistic dynamo amplification. Magnetic fields generated at inflation can have high enough amplitude only if their spectrum is very red. Here we show that helicity, which leads to an inverse cascade, can mitigate these limits. In particular, we find that helical fields generated at the QCD phase transition or at inflation with red spectrum are possible seeds for the dynamo. Helical fields generated at the electroweak phase transition are instead excluded as seeds at large scales. We also calculate the spectrum of gravitational waves generated by helical magnetic fields.

  6. Proposal for Environmental Observation System for Large Scale Gas Pipeline Networks Using Unmanned Airship

    NASA Astrophysics Data System (ADS)

    Shiho, Makoto; Horioka, Kazuhiko; Inoue, Gen; Onda, Masahiko; Leighty, William C.; Yokoo, Kuniyoshi; Ono, Shoichi; Ohashi, Kazuhiko; Hirata, Masaru

    2004-03-01

    Construction of a large scale natural gas pipeline network system in the Northeast Asian area has been proposed by several researchers, including Prof. Masaru Hirata, which will extend over tens of thousands of kilometers. To monitor the gas leakage, and to cope with any other hazardous problems, continuous surveillance of the network will be required. For this purpose, an environmental observation system for the large scale pipeline network is proposed. In this system unmanned airships are used as platforms for various environmental diagnostics. The unmanned airship is routed along the pipeline with the aid of GPS. Propulsion power of the air ship is transmitted from the ground bases by microwave; the microwave power stations are located every 100-200km along the pipeline. This paper describes the unmanned airships, environmental diagnostic systems, microwave generation tubes, and microwave powering system.

  7. Observations of two peculiar emission objects in the Large Magellanic Cloud

    NASA Technical Reports Server (NTRS)

    Kafatos, M.; Michalitsianos, A. G.; Allen, D. A.; Stencel, R. E.

    1983-01-01

    Ultraviolet and visual wavelength spectra were obtained of two peculiar emission objects, Henize S63 and Sanduleak's star in the Large Magellanic Cloud. Previously not observed in the near- or far-ultraviolet, both objects exhibit strong permitted and semiforbidden line emissions. Estimates based on the absolute continuum flux of the hot companion star in Hen S63 indicate that it rivals the luminosity of the carbon star primary. The emission-line profile structure in both objects does not suggest Wolf-Rayet type emission. Carbon in Sanduleak's star (LMC anonymous) is conspicuously absent, while N V, semiforbidden N IV, and semiforbidden N III dominate the UV emission-line spectrum. Nitrogen is overabundant with respect to carbon and oxygen in both objects. The large overabundance of nitrogen in Sanduleak's star suggests evidence for CNO processes material similar to that seen in Nu Car.

  8. “Benchmark” — a large observational study of Ontario beef breeding herds: Study design and collection of data

    PubMed Central

    McDermott, John J.; Alves, David M.; Anderson, Neil G.; Martin, S. Wayne

    1991-01-01

    The methods used in a large field study which investigated the health and productivity of Ontario beef breeding herds are described. Beginning in the calving season of 1986, 180 breeding herds on 170 randomly sampled farms were followed for a two year period, using producer records and annual farm visits. The response (cooperation) rate among the eligible producers initially contacted was 70%. Approximately two-thirds of producers maintained individual animal records, primarily calving season records. Approximately 40% recorded disease occurrences. The advantages, disadvantages, and interpretation of “on-farm” observational studies are discussed. PMID:17423817

  9. High-resolution sounding rocket observations of large-amplitude Alfven waves

    NASA Technical Reports Server (NTRS)

    Boehm, M. H.; Carlson, C. W.; Mcfadden, J. P.; Clemmons, J. H.; Mozer, F. S.

    1990-01-01

    Shear Alfven waves with amplitudes greater than 100 mV/m were observed on two recent sounding rocket flights. The largest waveforms are best described as a series of step functions, rather than as broadband noise or as single frequency waves. Complete two-dimensional E and B measurements at 4-ms time resolution were made, showing a downward propagation direction and implying insignificant reflection from the ionosphere at frequencies greater than 1 Hz. Intense, field-aligned, low-energy electron fluxes accompany the waves. Acceleration of these electrons by the Alfven waves is shown to be feasible. The waves in at least one case have a sufficently large ponderomotive potential to generate the observed density fluctuations of order one.

  10. Interpreting Observed Arctic Snow Trends with Large Ensembles of Climate Simulations

    NASA Astrophysics Data System (ADS)

    Mudryk, L. R.; Kushner, P. J.

    2012-12-01

    Snow is a key element of the Northern Hemisphere's energy budget, water balance, and climate sensitivity. While Northern Hemisphere mean snowfall and snow accumulation are expected to decrease as a result of warming caused by greenhouse gas emissions, combined changes in the temperature and precipitation patterns are complex enough to cause marked regional variations of either sign. Accurately predicting such regional changes in the coming decades is predicated on being able to properly simulate historical changes and being able to separate forced signals from climate noise. We present an analysis of Northern Hemisphere snow and temperature trends using large ensembles (20+ members) of the Community Earth System Model. We have generated two such large ensembles forced with historical emissions of greenhouse gases, aerosols and ozone during the period 1981-2010. The first ensemble uses a coupled ocean-atmosphere setup with a freely evolving ocean; the second uses the same atmospheric model forced by observed sea surface temperatures. Our results show that while the model is able to reproduce the observed climatology and variability of snow cover extent (as well as snow water equivalent to a lesser degree of fidelity), internal climate noise generates different spatial patterns of snow trends in different climate realizations. These patterns are related in an intuitive way to the temperature and circulation. While both ensembles capture the overall decreasing trend in snow cover extent observed during the spring season, there are differences in their magnitudes and spatial distribution. Following Shin and Sardeshmukh [2010], we discuss the role of the magnitude and spatial pattern of the sea surface temperature trends as they relate to the resulting snow trends. These connections promise to aid in interpretation of observations.

  11. 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. PMID:22086040

  12. Estimating the impact of satellite observations on the predictability of large-scale hydraulic models

    NASA Astrophysics Data System (ADS)

    Andreadis, Konstantinos M.; Schumann, Guy J.-P.

    2014-11-01

    Large-scale hydraulic models are able to predict flood characteristics, and are being used in forecasting applications. In this work, the potential value of satellite observations to initialize hydraulic forecasts is explored, using the Ensemble Sensitivity method. The impact estimation is based on the Local Ensemble Transform Kalman Filter, allowing for the forecast error reductions to be computed without additional model runs. The experimental design consisted of two configurations of the LISFLOOD-FP model over the Ohio River basin: a baseline simulation represents a 'best effort' model using observations for parameters and boundary conditions, whereas the second simulation consists of erroneous parameters and boundary conditions. Results showed that the forecast skill was improved for water heights up to lead times of 11 days (error reductions ranged from 0.2 to 0.6 m/km), 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. Moreover, water height observations had a negative impact on discharge forecasts for longer lead times although they did improve forecast skill for 1 and 3 days (up to 60 m3 / s / km). Lastly, the inundated area forecast errors were reduced overall for all examined lead times. Albeit, when examining a specific flood event the limitations of predictability were revealed suggesting that model errors or inflows were more important than initial conditions.

  13. Large-scale structure of solar wind as observed on the Prognoz 7 satellite

    NASA Technical Reports Server (NTRS)

    Yermolaev, Yu. I.

    1995-01-01

    Properties of different solar wind streams depend on the large scale structure of coronal magnetic field and dynamical phenomena in the solar atmosphere. We present average values and distributions of MHD parameters (density, velocity, temperature, fluxes of mass, momentum and energy, ratio of thermal and magnetic pressures, as well as helium abundance) as observed on board the Prognoz 7 satellite in the different types of the solar wind streams connected with solar corona structure and phenomena: (1) heliospheric current sheet, (2) streams from coronal holes, (3) streams from coronal streamers, (4) plasma disturbed by interplanetary shocks, and (5) coronal mass ejections. As for quasistationary streams of solar wind, maximum mass flux is recorded in the streams emanating from the coronal streamers while maximum thermal and kinetic energy fluxes are observed in the streams from the coronal holes. The momentum fluxes are equal in both types of streams. Maximum ratio of thermal and magnetic pressures is observed in heliospheric current sheet. The maximum helium abundance is observed in coronal mass ejection, it is higher in streams from coronal holes than in streams from streamers, and its dependences on density and mass flux are different in different types of the streams. Dynamics of alpha-particle velocity and temperature relative to protons in different streams is discussed.

  14. 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.

  15. 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.

  16. A fast-propagating, large-scale atmospheric gravity wave observed in the WAVE2004 campaign

    NASA Astrophysics Data System (ADS)

    Kubota, Minoru; Kawamura, Seiji; Abo, Makoto; Koizumi, Yoshiko; Murayama, Yasuhiro; Yamamori, Miho; Shiokawa, Kazuo; Otsuka, Yuichi; Uchiumi, Michihiro; Igarashi, Kiyoshi; Abe, Takumi; Oyama, Koh-Ichiro; Iwagami, Naomoto

    2006-11-01

    The Waves in Airglow Campaign in 2004 (WAVE2004), which aimed to elucidate the formation process of waves in airglow structures from both dynamical and chemical perspectives, was conducted using rocket-borne and ground-based instruments in Japan on 17 January 2004. In this experiment, we observed a large-scale atmospheric gravity wave (AGW), which appeared in both the vertical profiles of sodium density obtained by a Na lidar and the horizontal distributions of airglow emission obtained by an all-sky imager (ASI). Vertical propagation of the AGW accompanied by a shortening of its vertical wavelength was clearly visualized using the Na lidar data. The horizontal wavelength, horizontal phase velocity, period, and propagation direction of the AGW were estimated from the ASI data as 673-774 km, 107-122 m/s, ˜1.75 hours, and north-northeastward, respectively. Using these parameters and the MF radar wind, vertical wavelengths of the wave were calculated from the dispersion relation of gravity waves. The calculated vertical wavelengths were comparable at altitudes of 85.5 km and 93.25 km to those estimated from the variation of the sodium density. Using a simple ray tracing technique, the AGW was traced back to the southern edge of the distorted jet stream near tropopause. This result strongly suggests that an unstable baroclinic wave associated with ageostrophic motions in the jet stream was the wave source of the large-scale AGW observed in the WAVE2004.

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

    SciTech Connect

    Basilakos, Spyros; Bauer, Florian; Solà, Joan, E-mail: svasil@academyofathens.gr, E-mail: fbauerphysik@eml.cc, E-mail: sola@ecm.ub.es [High Energy Physics Group, Dept. ECM, Univ. de Barcelona, Av. Diagonal 647, E-08028 Barcelona, Catalonia (Spain)

    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 ?CDM 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.

  18. Observation of large low temperature magnetocaloric effect in HoCu2

    NASA Astrophysics Data System (ADS)

    Karmakar, S. K.; Giri, S.; Majumdar, S.

    2015-05-01

    We report the observation of large low temperature magnetocaloric effect and magnetoresistance in the rare-earth based intermetallic compound HoCu2. The compound undergoes an antiferromagnetic type ordering below about TN = 10.5 K, which is second order in nature. The magnetocaloric effect in terms of entropy change under the application of 50 kOe of field is found to have a maximum value of -19.3 J kg-1 K-1 peaking around TN, and an appreciable value of relative cooling power of 268 J kg-1 was associated with it. The sample also shows giant negative magnetoresistance with its value as high as -36.5% around TN for 50 kOe of field. Field induced second order metamagnetic transition is found to be responsible for the observed magnetocaloric and magnetoresistance behaviors in the sample. The sample is devoid of any thermal or field hysteresis by virtue of the second order nature of the transitions, which enables us to exploit large reversible magnetic cooling at cryogenic temperatures.

  19. 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 observed. All three events were also captured by polarimetric radars, namely the S-band CHILL radar operated by Colorado State University (Brunkow et al., 2000), the C-band ARMOR radar (Petersen et al., 2007) operated by University of Alabama in Huntsville, and NEXRADKVNX, operated by the US National Weather Service, respectively. For the last event, several other radar observations were also made, including two X-band radars operated by the US Dept. of Energy. Analyses of 2DVD data in conjunction with the corresponding radar observations are presented, along with some discussion on sampling issues related to the measurements of such large rain drops. The latter is addressed using maximum diameter D(sub max) measurements from 1-minute DSDs using two collocated 2DVDs for 37 events in Huntsville.

  20. 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 moisture jumps, and entrainment rates. Using these diverse cases, we will begin to tease apart the cloud-scale factors governing drizzle rates. Initial results for question (i) suggest that in some cases enhancements of 1 to 2 orders of magnitude over predicted collision rates are necessary to reproduce observations.

  1. 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. Using this catalog, I have scaled the Bolocam SZE measurements with X-ray mass approximations in an effort to characterize the SZE signal as a viable mass probe for cosmology. This work has confirmed the SZE to be a low-scatter tracer of cluster mass. The analysis has also revealed how sensitive the SZE-mass scaling is to small biases in the adopted mass approximation. Future Bolocam analysis efforts are set on resolving these discrepancies by approximating cluster mass jointly with different observational probes.

  2. Forthcoming Coronal Mass Ejection Observations with the Very Large Array (VLA)

    NASA Astrophysics Data System (ADS)

    Spangler, Steven R.; Kooi, Jason E.; Sink, Joseph R.

    2015-04-01

    It is widely recognized that measurement of Faraday rotation through a coronal mass ejection (CME) provides unique information on the internal plasma structure of the CME, particularly the form of the magnetic field. The Faraday rotation measure is proportional to the path integral through the CME of the electron density and the line-of-sight component of the magnetic field. In spite of this importance, there are relatively few measurements of Faraday rotation produced by a CME. The Very Large Array (VLA) of the National Radio Astronomy Observatory is an outstanding instrument for measurement of Faraday rotation, and its capabilities have been greatly improved by an upgrade over the past decade. In the case of VLA observations, the trans-coronal sources of radio waves are radio galaxies and quasars. A difficulty in measuring Faraday rotation of a CME is the unpredictability of the CME phenomenon. It is difficult to predict whether a given line of sight to a background source will be occulted by a CME on a given day. We have received approval to carry out ``triggered'' CME observations with the VLA in the summer of 2015. In these observations, we will rely on coronagraph detections of a CME to initiate VLA observations of select background sources. This observing mode will improve on one previously used, in which a decision to observe had to be made a day or more in advance. The goal of these observations will be to secure Faraday rotation measurements on one or more lines of sight that pass through critical parts of a CME. In this paper, we will describe our planned triggering scheme, the selection of background sources, choice of observing frequency and selection of lines of sight that can best determine the plasma structure of a CME. Our planning also depends on prior experience in measurement of coronal Faraday rotation, and Faraday rotation ``transients'' associated with CMEs. This work was supported at the University of Iowa by grant ATM09-56901 from the National Science Foundation.

  3. Very Large Telescope observations of Gomez's Hamburger: Insights into a young protoplanet candidate

    NASA Astrophysics Data System (ADS)

    Berné, O.; Fuente, A.; Pantin, E.; Bujarrabal, V.; Baruteau, C.; Pilleri, P.; Habart, E.; Ménard, F.; Cernicharo, J.; Tielens, A. G. G. M.; Joblin, C.

    2015-06-01

    Planets are thought to form in the gas and dust disks around young stars. In particular, it has been proposed that giant planets can form through the gravitational instability of massive extended disks around intermediate-mass stars. However, we still lack direct observations to constrain this mechanism. We have spatially resolved the 8.6 and 11.2 ?m emission of a massive protoplanetary disk seen edge on around an A star, Gomez's Hamburger (GoHam), using VISIR at the Very Large Telescope. A compact region situated at a projected distance of 350 ± 50 AU south of the central star is found to have a reduced emission. This asymmetry is fully consistent with the presence of a cold density structure, or clump, identified in earlier CO observations, and we derive physical characteristics consistent with those observations: a mass of 0.8-11.4 Jupiter masses (for a dust-to-gas mass ratio of 0.01), a radius of about 102 astronomical units, and a local density of about 107 cm-3. Based on this evidence, we argue that this clump, which we call GoHam b, is a promising candidate for a young protoplanet formed by gravitational instability that might be representative of the precursors of massive planets observed around A stars, such as HR 8799 or Beta pictoris. More detailed studies at high angular resolution are needed to better constrain the physical properties of this object to confirm this proposal. Based on observations collected at the European Southern Observatory, Chile under program ID 385.C-0762A.Appendices are available in electronic form at http://www.aanda.org

  4. Rapid formation of large aggregates during the spring bloom of Kerguelen Island: observations and model comparisons

    NASA Astrophysics Data System (ADS)

    Jouandet, M.-P.; Jackson, G. A.; Carlotti, F.; Picheral, M.; Stemmann, L.; Blain, S.

    2014-08-01

    While production of aggregates and their subsequent sinking is known to be one pathway for the downward movement of organic matter from the euphotic zone, the rapid transition from non-aggregated to aggregated particles has not been reported previously. We made one vertical profile of particle size distributions (PSD; sizes ranging from 0.052 to several millimeters in equivalent spherical diameter) at pre-bloom stage and seven vertical profiles 3 weeks later over a 48 h period at early bloom stage using the Underwater Vision Profiler during the Kerguelen Ocean and Plateau Compared Study cruise 2 (KEOPS2, October-November 2011). In these naturally iron-fertilized waters southeast of Kerguelen Island (Southern Ocean), the total particle numerical abundance increased by more than fourfold within this time period. A massive total volume increase associated with particle size distribution changes was observed over the 48 h survey, showing the rapid formation of large particles and their accumulation at the base of the mixed layer. The results of a one-dimensional particle dynamics model support coagulation as the mechanism responsible for the rapid aggregate formation and the development of the VT subsurface maxima. The comparison of VT profiles between early bloom stage and pre-bloom stage indicates an increase of particulate export below 200 m when bloom has developed. These results highlight the role of coagulation in forming large particles and triggering carbon export at the early stage of a naturally iron-fertilized bloom, while zooplankton grazing may dominate later in the season. The rapid changes observed illustrate the critical need to measure carbon export flux with high sampling temporal resolution. Our results are the first published in situ observations of the rapid accumulation of marine aggregates and their export and the general agreement of this rapid event with a model of phytoplankton growth and coagulation.

  5. The Right Circular Cylinder

    NSDL National Science Digital Library

    2010-12-02

    This learning object from Wisc-Online covers the right circular cylinder, examining the properties and components of the shape. The lesson uses the geometric formulas for finding the volume and surface area of the shape. Practice questions are also included.

  6. The Right Circular Cone

    NSDL National Science Digital Library

    Jensen, Douglas

    2005-01-01

    This learning object from Wisc-Online covers the right circular cone, examining the properties and components of the shape. The lesson uses the geometric formulas for finding the volume and surface area of the shape. Practice questions are also included.

  7. 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…

  8. Circular Motion and Forces

    NSDL National Science Digital Library

    Wolfgang Christian

    A heavy ball is attached to a string and swung in a circular path in a horizontal plane as shown in the animation. At the point indicated the string suddenly breaks at the ball. Four animations represent possible results when the string breaks at point P.

  9. Observational Requirements for Ly? Forest Tomographic Mapping of Large-scale Structure at z ~ 2

    NASA Astrophysics Data System (ADS)

    Lee, Khee-Gan; Hennawi, Joseph F.; White, Martin; Croft, Rupert A. C.; Ozbek, Melih

    2014-06-01

    The z >~ 2 Ly? 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 los ? [360, 1200, 3300] deg-2 at limiting magnitudes of g = [24.0, 24.5, 25.0], resulting in transverse sightline separations of langd rang ? [3.6, 1.9, 1.2] h -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 ?/lang?rang ~ 1. For the VLT/VIMOS spectrograph, exposure times t exp = [4, 6, 10] hr are sufficient for maps with spatial resolution epsilon3D = [5.0, 3.2, 2.3] h -1 Mpc. Assuming ~250 h -1 Mpc is probed along the line of sight, 1 deg2 of survey area would cover a comoving volume of ?106 h -3 Mpc3 at langzrang ~ 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.

  10. Ionospheric observations of underground nuclear explosions (UNE) using GPS and the Very Large Array

    NASA Astrophysics Data System (ADS)

    Park, Jihye; Helmboldt, Joseph; Grejner-Brzezinska, Dorota A.; Frese, Ralph R. B.; Wilson, Thomas L.

    2013-07-01

    Observations from Global Positioning System (GPS) receivers and the Very Large Array (VLA) radio telescope recorded traveling ionospheric disturbances (TID) from underground nuclear explosions (UNEs), detonated in September 1992. The slant TEC (STEC) data derived from GPS observations were processed for all ray paths to isolate TIDs. For the TIDs from the Hunters Trophy test on 18 September 1992 and the Divider test on 23 September 1992, the propagated mean velocities of the TIDs were about 573 m/s and 740 m/s with standard deviations of 85 m/s and 135 m/s, respectively. For the VLA observations, the spectral analysis produced three-dimensional fluctuation spectral cubes for the Hunters Trophy event. The arrival time of the TID at the VLA implied a propagation speed of 570-710 m/s. This study suggests the global availability of GNSS tracking networks and new low-frequency (VHF) radio telescopes may offer a method of UNE detection and characterization, which could complement the International Monitoring System (IMS).

  11. Large Fields of Sub-circular Depressions On The Carnegie Ridge Flanks Discovered During The French German Salieri Cruise (r\\/v Sonne, 22-08\\/16-09 2001)

    Microsoft Academic Search

    F. Michaud; J. Y. Collot; M. A. Gutscher; P. Charvis; E. Flüh; E. Santana

    2002-01-01

    During the SALIERI Cruise offshore Ecuador, multibeam bathymetry was collected with the Simrad EM120 of the R\\/V SONNE. The most conspicuous features discov- ered on the Carnegie Ridge are fields of circular closed depressions distributed along the mid-slope of the ridge northern and southern flanks at depths of 1500 to 2600 m. These circular depressions are 1-4 km wide and

  12. CARIBIC DOAS observations of nitrous acid and formaldehyde in a large convective cloud

    NASA Astrophysics Data System (ADS)

    Heue, K.-P.; Riede, H.; Walter, D.; Brenninkmeijer, C. A. M.; Wagner, T.; Frieß, U.; Platt, U.; Zahn, A.; Stratmann, G.; Ziereis, H.

    2014-07-01

    The chemistry in large thunderstorm clouds is influenced by local lightning-NOx production and uplift of boundary layer air. Under these circumstances trace gases like nitrous acid (HONO) or formaldehyde (HCHO) are expected to be formed or to reach the tropopause region. However, up to now only few observations of HONO at this altitude have been reported. Here we report on a case study where enhancements in HONO, HCHO and nitrogen oxides (NOx) were observed by the CARIBIC flying laboratory (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container). The event took place in a convective system over the Caribbean Sea in August 2011. Inside the cloud the light path reaches up to 100 km. Therefore the DOAS instrument on CARIBIC was very sensitive to the tracers inside the cloud. Based on the enhanced slant column densities of HONO, HCHO and NO2, average mixing ratios of 37, 468 and 210 ppt, respectively, were calculated. These data represent averages for constant mixing ratios inside the cloud. However, a large dependency on the assumed profile is found; for HONO a mixing ratio of 160 ppt is retrieved if the total amount is assumed to be situated in the uppermost 2 km of the cloud. The NO in situ instrument measured peaks up to 5 ppb NO inside the cloud; the background in the cloud was about 1.3 ppb, and hence clearly above the average outside the cloud (? 150 ppt). The high variability and the fact that the enhancements were observed over a pristine marine area led to the conclusion that, in all likelihood, the high NO concentrations were caused by lighting. This assumption is supported by the number of flashes that the World Wide Lightning Location Network (WWLLN) counted in this area before and during the overpass. The chemical box model CAABA is used to estimate the NO and HCHO source strengths which are necessary to explain our measurements. For NO a source strength of 10 × 109 molec cm-2 s-1 km-1 is found, which corresponds to the lightning activity as observed by the World Wide Lightning Location network, and lightning emissions of 5 × 1025 NO molec flash-1 (2.3-6.4 × 1025). The uncertainties are determined by a change of the input parameters in the box model, the cloud top height and the flash density. The emission rate per flash is scaled up to a global scale and 1.9 (1.4-2.5) tg N a-1 is estimated. The HCHO updraught is of the order of 120 × 109 molec cm-2 s-1 km-1. Also isoprene and CH3OOH as possible HCHO sources are discussed.

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

    SciTech Connect

    Ji, Minbiao; /SLAC, PULSE /Stanford U., Phys. Dept.; Odelius3, Michael; /Stockholm U.; 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.

  14. Helicity flip of the backscattered circular polarized light

    Microsoft Academic Search

    Vladimir Kuzmin; Igor Meglinski

    2010-01-01

    We study coherent and non-coherent backscattering of circularly polarized light from turbid media. We find that the sign of helicity of circular polarized light does not change for a medium of point-like scatterers and can change significantly for the medium with high anisotropy of scatterers. The helicity flip is observed when the light scattering is described in terms of the

  15. Mechanical and hydrologic basis for the rapid motion of a large tidewater glacier. 1: Observations

    NASA Technical Reports Server (NTRS)

    Meier, Mark; Lundstrom, Scott; Stone, Dan; Kamb, Barclay; Engelhardt, Hermann; Humphrey, Neil; Dunlap, William W.; Fahnestock, Mark; Krimmel, Robert M.; Walters, Roy

    1994-01-01

    Measurements of glacier flow velocity and basal water pressure at two sites on Columbia Glacier, Alaska, are combined with meteorological and hydrologic data to provide an observational basis for assessing the role of water storage and basal water pressure in the rapid movement of this large glacier. During the period from July 5 to August 31, 1987, coordinated observations were made of glacier surface motion and of water level in five boreholes drilled to (or in one case near to) the glacier bed at two sites, 5 and 12 km from the terminus. Glacier velocities increased downglacier in this reach from about 4 m/d to about 7 m/d. Three types of time variation in velocity and other variables were revealed: (1) Diurnal fluctuation in water input/output, borehole water level, and ice velocity (fluctuation amplitude 5 to 8%); (2) Speed-up events in glacier motion (15-30% speed-up), lasting about three days, and ocurring at times of enhanced input of water, in some cases from rain and in others from ice ablation enhanced by strong, warm winds; (3) 'Extra-slowdown' events, in which, after a speed-up event, the ice velocity decreased in about 3 days to a level consistently lower than that prior to the speed-up event. All of the time variations were due, directly or indirectly, to variations in water input to the glacier.

  16. 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. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Aschwanden, M. J. [Lockheed Martin Advanced Technology Center, Solar and Astrophysics Laboratory, Organization ADBS, Building 252, 3251 Hanover Street, Palo Alto, CA 94304 (United States)], E-mail: Erwin.Verwichte@warwick.ac.uk

    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.

  17. Temperature dependent EUV spectra of Gd, Tb and Dy ions observed in the Large Helical Device

    NASA Astrophysics Data System (ADS)

    Suzuki, C.; Koike, F.; Murakami, I.; Tamura, N.; Sudo, S.

    2015-07-01

    We have observed a number of different types of extreme ultraviolet (EUV) spectra from highly charged gadolinium (Gd), terbium (Tb) and dysprosium (Dy) ions in optically thin plasmas produced in the Large Helical Device at the National Institute for Fusion Science. Temporal changes in EUV spectra in the 6–9 nm region subsequent to the injections of solid pellets were measured by a grazing incidence spectrometer. The spectra rapidly change from discrete features into unresolved transition arrays (UTAs) following a drop in the electron temperature after the heating power is reduced. In particular, extremely narrowed UTA features, which comprise spectral lines of Ag-like, Pd-like and neighboring ion stages, are observed when the peak electron temperature is less than 0.45 keV due to the formation of hollow plasmas. Some discrete spectral lines of Cu-like and Ag-like ions have been identified in the high and low temperature plasmas, respectively, some of which are experimentally identified for the first time.

  18. Observation of Supernova Remnant IC443 with the Fermi Large Area Telescope

    E-print Network

    Abdo, A A

    2010-01-01

    We report observation of the supernova remnant IC443 (G189.1+3.0) with the Fermi Gamma-ray Space Telescope Large Area Telescope (LAT) in the energy band between 200MeV and 50GeV. IC443 is a shell-type supernova remnant with mixed morphology located off the outer Galactic plane where high-energy emission has been detected in the X-ray, GeV and TeV gamma-ray bands. Past observations suggest IC443 has been interacting with surrounding interstellar matter. Proximity between dense shocked molecular clouds and GeV-TeV gamma-ray emission regions detected by EGRET, MAGIC and VERITAS suggests an interpretation that cosmic-ray (CR) particles are accelerated by the SNR. With the high gamma-ray statistics and broad energy coverage provided by the LAT, we accurately characterize the gamma-ray emission produced by the CRs accelerated at IC443. The emission region is extended in the energy band with theta_68 = 0.27 deg +/- 0.01 deg (stat) +/- 0.03 deg (sys) for an assumed 2-dimensional Gaussian profile and overlaps almost c...

  19. Modeling and surface observations of arsenic dispersion from a large Cu-smelter in southwestern Europe

    NASA Astrophysics Data System (ADS)

    Chen, Bing; Stein, Ariel F.; Castell, Nuria; de la Rosa, Jesus D.; Sanchez de la Campa, Ana M.; Gonzalez-Castanedo, Yolanda; Draxler, Roland R.

    2012-03-01

    Arsenic is a toxic element for human health. Consequently, a mean annual target level for arsenic at 6 ng m-3 in PM10 was established by the European Directive 2004/107/CE to take effect January 2013. Cu-smelters can contribute to one-third of total emissions of arsenic in the atmosphere. Surface observations taken near a large Cu-smelter in the city of Huelva (Spain) show hourly arsenic concentrations in the range of 0-20 ng m-3. The arsenic peaks of 20 ng m-3 are higher than values normally observed in urban areas around Europe by a factor of 10. The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model has been employed to predict arsenic emissions, transport, and dispersion from the Cu-smelter. The model utilized outputs from different meteorological models and variations in the model physics options to simulate the uncertainty in the dispersion of the arsenic plume. Modeling outputs from the physics ensemble for each meteorological model driving HYSPLIT show the same number of arsenic peaks. HYSPLIT coupled with the Weather Research and Forecasting (WRF-ARW) meteorological output predicted the right number of peaks for arsenic concentration at the observation site. The best results were obtained when the WRF simulation used both four-dimensional data assimilation and surface analysis nudging. The prediction was good in local sea breeze circulations or when the flow was dominated by the synoptic scale prevailing winds. However, the predicted peak was delayed when the transport and dispersion was under the influence of an Atlantic cyclone. The calculated concentration map suggests that the plume from the Cu-smelter can cause arsenic pollution events in the city of Huelva as well as other cities and tourist areas in southwestern Spain.

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

    SciTech Connect

    Sarma, A. P.; Eftimova, M. [Physics Department, DePaul University, 2219 N. Kenmore Ave., Byrne Hall 211, Chicago, IL 60614 (United States)] [Physics Department, DePaul University, 2219 N. Kenmore Ave., Byrne Hall 211, Chicago, IL 60614 (United States); Brogan, C. L. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)] [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Bourke, T. L. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)] [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Troland, T. H., E-mail: asarma@depaul.edu [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States)

    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.

  1. Volume imaging lidar observations and large-eddy simulations of convective internal boundary layers

    NASA Astrophysics Data System (ADS)

    Mayor, Shane David

    Volume imaging lidar data collected from a site on the western shore of Lake Michigan during the Lake-Induced Convection Experiment provide new observations of convective internal boundary layers and are used to test large-eddy simulations (LESs). Two-dimensional correlation functions of the aerosol backscattering data on horizontal planes reveal the mean motion, orientation, size, spacing and lifetime of the aerosol structures as a function of altitude and offshore distance. Observations show the flow accelerating as a result of the increase in convective mixing and decrease in surface roughness. Although individual lidar backscatter images show remarkable detail of the eddy structure, the averaged backscatter is very homogeneous and does not indicate a well-defined edge to the internal boundary layer despite the tremendous increase in surface heat and moisture flux over the lake. LESs of January 13 were performed using the University of Wisconsin's nonhydrostatic scalable model. To simulate the horizontal homogeneity of turbulence over the land and the inhomogeneity over the lake, a perturbation recycling method was added to the inflow boundary condition. Optical aerosol scattering was estimated from the model output to enable comparison with the lidar data. The simulated lidar backscattering is used for computing correlation functions that can be compared with those from the observed backscatter data. Comparisons show that the LES (1)tends to have smaller convective structures at the smallest scales simulated, (2)tends to produce more elongated convective structures that are aligned with the mean wind direction, and (3)fails to simulate the apparent organization of convective structures by gravity waves. The absence of strong gravity waves in the simulations is probably caused by the limited depth of the model domain and limitations of the lateral boundary conditions.

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

    SciTech Connect

    Veronig, A. M.; Muhr, N.; Kienreich, I. W.; Temmer, M. [Institute of Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria); Vrsnak, B., E-mail: asv@igam.uni-graz.a [Hvar Observatory, Faculty of Geodesy, Kaciceva 26, 1000 Zagreb (Croatia)

    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.

  3. Observation of Supernova Remnant IC 443 with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Cillis, A. N.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giavitto, G.; Giebels, B.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hughes, R. E.; Jackson, M. S.; Jóhannesson, G.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocian, M. L.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Mazziotta, M. N.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Rochester, L. S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Ryde, F.; Sadrozinski, H. F.-W.; Sanchez, D.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Strong, A. W.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Van Etten, A.; Vasileiou, V.; Venter, C.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Ylinen, T.; Ziegler, M.

    2010-03-01

    We report observation of the supernova remnant (SNR) IC 443 (G189.1+3.0) with the Fermi Gamma-ray Space Telescope Large Area Telescope (LAT) in the energy band between 200 MeV and 50 GeV. IC 443 is a shell-type SNR with mixed morphology located off the outer Galactic plane where high-energy emission has been detected in the X-ray, GeV and TeV gamma-ray bands. Past observations suggest IC 443 has been interacting with surrounding interstellar matter. Proximity between dense shocked molecular clouds and GeV-TeV gamma-ray emission regions detected by EGRET, MAGIC, and VERITAS suggests an interpretation that cosmic-ray (CR) particles are accelerated by the SNR. With the high gamma-ray statistics and broad energy coverage provided by the LAT, we accurately characterize the gamma-ray emission produced by the CRs accelerated at IC 443. The emission region is extended in the energy band with ?68 = 0fdg27 ± 0fdg01(stat) ± 0fdg03(sys) for an assumed two-dimensional Gaussian profile and overlaps almost completely with the extended source region of VERITAS. Its centroid is displaced significantly from the known pulsar wind nebula (PWN) which suggests the PWN is not the major contributor in the present energy band. The observed spectrum changes its power-law slope continuously and continues smoothly to the MAGIC and VERITAS data points. The combined gamma-ray spectrum (200 MeV

  4. Nonuniform circular ensembles.

    PubMed

    Kumar, Sandeep; Pandey, Akhilesh

    2008-08-01

    We consider circular ensembles with nonuniform weight functions. We investigate the universality of short-range and long-range level fluctuations, which are important in the study of quantum chaotic systems. We analyze a set of hierarchic relations among the correlation functions to obtain the level density for a wide class of potentials and to demonstrate universality of correlation functions in the case of weak periodic potentials (where the term potential refers to the logarithm of the weight function). Analytic study of circular unitary ensemble is done with the help of orthogonal polynomials on the unit circle. For circular orthogonal and symplectic ensembles, we introduce skew-orthogonal polynomials on the unit circle. We consider the asymptotic forms of the polynomials for the three types of ensembles with weak potentials to give a proof of the universality. The analytic results are verified by Monte Carlo simulations of the ensembles with different weight functions. We also discuss the implications of these results in the context of conductance fluctuations in mesoscopic systems and show that the universality breaks down for strong potentials. PMID:18850918

  5. Exploring the origin of a large cavity in Abell 1795 using deep Chandra observations

    NASA Astrophysics Data System (ADS)

    Walker, S. A.; Fabian, A. C.; Kosec, P.

    2014-12-01

    We examine deep stacked Chandra observations of the galaxy cluster Abell 1795 (over 700 ks) to study in depth a large (34 kpc radius) cavity in the X-ray emission. Curiously, despite the large energy required to form this cavity (4PV = 4 × 1060 erg), there is no obvious counterpart to the cavity on the opposite side of the cluster, which would be expected if it has formed due to jets from the central active galactic nucleus (AGN) inflating bubbles. There is also no radio emission associated with the cavity, and no metal enhancement or filaments between it and the brightest cluster galaxy, which are normally found for bubbles inflated by AGN which have risen from the core. One possibility is that this is an old ghost cavity, and that gas sloshing has dominated the distribution of metals around the core. Projection effects, particularly the long X-ray bright filament to the south-east, may prevent us from seeing the companion bubble on the opposite side of the cluster core. We calculate that such a companion bubble would easily have been able to uplift the gas in the southern filament from the core. Interestingly, it has recently been found that inside the cavity is a highly variable X-ray point source coincident with a small dwarf galaxy. Given the remarkable spatial correlation of this point source and the X-ray cavity, we explore the possibility that an outburst from this dwarf galaxy in the past could have led to the formation of the cavity, but find this to be an unlikely scenario.

  6. 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)

  7. 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 this paper is that even in the presence of growing, unstable waves, the mixing barriers around

  8. Rain Characteristics and Large-Scale Environment Associated with Extreme Precipitation Events Based on TRMM Observations

    NASA Astrophysics Data System (ADS)

    Zhou, Y.; Lau, W. K.

    2012-12-01

    This study utilizes the Precipitation Feature (PF) database developed at the University of Utah to analyze extreme precipitation events from 13-year TRMM observations. Characteristics of instantaneous extreme volumetric PFs, their geophysical distributions and diurnal variations are examined and compared to those of intermediate and small systems. It is found that the instantaneous PF exhibits much larger scale range than daily gridded precipitation, with those at top 1% of PFs two orders of magnitude greater than the medium PF but contributing to over 50% of instantaneous rainfall. The study shows that extreme PFs are significantly larger, deeper and colder than the lower 80% of the PFs. NCEP reanalysis shows a systematic increase in surface moist static energy (MSE) with larger PFs but convective available potential energy (CAPE) levels off for extremely large systems. Mid-level relative humidity and total precipitable water increase consistently for increasingly heavy precipitation events, suggesting a potential role of increasing moisture in a warming climate in producing extreme precipitation events.

  9. Soft X-ray observations of large-scale coronal active region brightenings

    NASA Technical Reports Server (NTRS)

    Rust, D. M.; Webb, D. F.

    1977-01-01

    One hundred fifty-six large-scale enhancements of X-ray emission from solar active regions were studied on full-disk filterheliograms to determine characteristic morphology and expansion rates for heated coronal plasma. The X-ray photographs were compared with H-alpha observations of flares, sudden filament disappearances, sprays, and loop prominence systems (LPS). Eighty-one percent of the X-ray events were correlated with H-alpha filament activity, but only 44% were correlated with reported H-alpha flares. The X-ray enhancements took the form of loops or arcades of loops ranging in length from 60,000 km to 520,000 km and averaging 15,000 km in width. Lifetimes ranged from at least 3 hr to more than 24 hr. The event frequency was approximately 1.4 per day. X-ray loop arcades evolved from sharp-edged clouds in cavities vacated by rising H-alpha filaments. Expansion velocities of the loops were about 50 km/s immediately after excitation and 1-10 km/s several hours later. These long-lived loop arcades are identified with LPS, and it is suggested that the loops outlined magnetic fields which were reconnecting after filament eruptions. Another class of X-ray-enhanced loops stretched outside active regions and accompanied sprays or lateral filament ejections. It is suggested that these loops outlined closed magnetic fields guiding slow-mode shocks from flares and filament eruptions.

  10. Fermi Large Area Telescope Observations of the Vela-X Pulsar Wind Nebula

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; 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.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Chekhtman, A.; Chung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; de Angelis, A.; de Palma, F.; Dormody, M.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gehrels, N.; Germani, S.; Giavitto, G.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Harding, A. K.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Jackson, M. S.; Jóhannesson, G.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Johnston, S.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Lemoine-Goumard, M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Marelli, M.; Mazziotta, M. N.; McEnery, J. E.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nolan, P. L.; Norris, J. P.; Noutsos, A.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Ray, P. S.; Rea, N.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Ryde, F.; Sadrozinski, H. F.-W.; Sanchez, D.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Van Etten, A.; Vasileiou, V.; Venter, C.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Weltevrede, P.; Winer, B. L.; Wood, K. S.; Ylinen, T.; Ziegler, M.

    2010-04-01

    We report on gamma-ray observations in the off-pulse window of the Vela pulsar PSR B0833-45 using 11 months of survey data from the Fermi Large Area Telescope (LAT). This pulsar is located in the 8° diameter Vela supernova remnant, which contains several regions of non-thermal emission detected in the radio, X-ray, and gamma-ray bands. The gamma-ray emission detected by the LAT lies within one of these regions, the 2° × 3° area south of the pulsar known as Vela-X. The LAT flux is significantly spatially extended with a best-fit radius of 0fdg88 ± 0fdg12 for an assumed radially symmetric uniform disk. The 200 MeV to 20 GeV LAT spectrum of this source is well described by a power law with a spectral index of 2.41 ± 0.09 ± 0.15 and integral flux above 100 MeV of (4.73 ± 0.63 ± 1.32) × 10-7 cm-2 s-1. The first errors represent the statistical error on the fit parameters, while the second ones are the systematic uncertainties. Detailed morphological and spectral analyses give strong constraints on the energetics and magnetic field of the pulsar wind nebula system and favor a scenario with two distinct electron populations.

  11. Observation of the low to high confinement transition in the large helical device

    SciTech Connect

    Toi, K.; Ohdachi, S.; Yamamoto, S.; Sakakibara, S.; Narihara, K.; Tanaka, K.; Morita, S.; Morisaki, T.; Goto, M.; Takagi, S.; Watanabe, F.; Nakajima, N.; Watanabe, K.Y.; Ida, K.; Ikeda, K.; Inagaki, S.; Kaneko, O.; Kawahata, K.; Komori, A.; Masuzaki, S. [National Institute for Fusion Science, Toki 509-5292 (Japan); Department of Energy Engineering and Science, Nagoya University, Nagoya 464-8603 (Japan); National Institute for Fusion Science, Toki 509-5292 (Japan); Department of Energy Engineering and Science, Nagoya University, Nagoya 464-8603 (Japan); National Institute for Fusion Science, Toki 509-5292 (Japan)] [and others

    2005-02-01

    The low to high confinement transition has been observed on the large helical device [A. Iiyoshi, A. Komori, A. Ejiri et al., Nucl. Fusion 39, 1245 (1999)], exhibiting rapid increase in edge electron density with sharp depression of H{sub {alpha}} emission. The transition occurs in low toroidal field (B{sub t}=0.5-0.75 T) discharges and are heated by high power neutral beam injection. The plasma thus has a relatively high value ({approx}1.5%) of the volume averaged {beta} value. The electron temperature and density profiles have steep gradients at the edge region which has high magnetic shear but is at a magnetic hill. Formation of the edge transport barrier leads to enhanced activities of the interchange type of modes with m=2/n=3 (m,n are the poloidal and toroidal mode numbers) in the edge region. At present, these magnetohydrodynamic activities limit the rise of the stored energy; the resultant increment of the stored energy remains modest.

  12. Gamma-ray observations of the Orion Molecular Clouds with the Fermi Large Area Telescope

    E-print Network

    Ackermann, 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; Caliandro, G A; Cameron, R A; Caraveo, P A; Cecchi, C; Chekhtman, A; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; D'Ammando, F; de Angelis, A; de Palma, F; Dermer, C D; Silva, E do Couto e; Drell, P S; Drlica-Wagner, A; Enoto, T; Falletti, L; Favuzzi, C; Fegan, S J; Ferrara, E C; Focke, W B; Fukazawa, Y; Fukui, Y; Fusco, P; Gargano, F; Gasparrini, D; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Guiriec, S; Hadasch, D; Hanabata, Y; Harding, A K; Hayashida, M; Hayashi, K; Horan, D; Hou, X; Hughes, R E; Jackson, M S; Jóhannesson, G; Johnson, A S; Kamae, T; Katagiri, H; Kataoka, J; Kerr, M; Knödlseder, J; Kuss, M; Lande, J; Larsson, S; Lee, S -H; Longo, F; Loparco, F; Lovellette, M N; Lubrano, P; Makishima, K; Mazziotta, M N; Mehault, J; Mitthumsiri, W; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Naumann-Godo, M; Nishino, S; Norris, J P; Nuss, E; Ohno, M; Ohsugi, T; Okumura, A; Orienti, M; Orlando, E; Ormes, J F; Ozaki, M; Paneque, D; Panetta, J H; Parent, D; Pelassa, V; Pesce-Rollins, M; Pierbattista, M; Piron, F; Pivato, G; Porter, T A; Rainò, S; Razzano, M; Reimer, A; Reimer, O; Roth, M; Sadrozinski, H F -W; Sgrò, C; Siskind, E J; Spandre, G; Spinelli, P; Strong, A W; Takahashi, H; Takahashi, T; Tanaka, T; Thayer, J G; Thayer, J B; Tibolla, O; Tinivella, M; Torres, D F; Tramacere, A; Troja, E; Uchiyama, Y; Usher, T L; Vandenbroucke, J; Vasileiou, V; Vianello, G; Vitale, V; Waite, A P; Wang, P; Winer, B L; Wood, K S; Yang, Z; Zimmer, S

    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 \\sim100 MeV and \\sim100 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 \\sim10% 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 (WCO) at a 1{\\deg} \\times1{\\deg} pixel level. The correlation is found to be linear over a WCO range of ~10 fold when divided in 3 regions, suggesting penetration of nuclear CRs to most of the cloud volumes. The Wco-to-mass conversion factor, Xco, is found to be \\sim2.3\\times1...

  13. 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.

  14. ASCA observations of the Large Magellanic Cloud supernova remnant sample: Typing supernovae from their remnants

    NASA Technical Reports Server (NTRS)

    Hughes, John P.; Hayashi, Ichizo; Helfand, David; Hwang, Una; Itoh, Masayuki; Kirshner, Robert; Koyama, Katsuji; Markert, Thomas; Tsunemi, Hiroshi; Woo, Jonathan

    1995-01-01

    We present our first results from a study of the supernova remnants (SNRs) in the Large Magellanic Cloud (LMC) using data from ASCA. The three remnants we have analyzed to date, 0509-67.5, 0519-69.0, and N103B, are among the smallest, and presumably also the youngest, in the Cloud. The X-ray spectra of these SNRs show strong K alpha emission lines of silicon, sulfur, argon, and calcium with no evidence for corresponding lines of oxygen, neon, or magnesium. The dominant feature in the spectra is a broad blend of emission lines around 1 keV which we attribute to L-shell emission lines of iron. Model calculations (Nomoto, Thielemann, & Yokoi 1984) show that the major products of nucleosynthesis in Type Ia supernovae (SNs) are the elements from silicon to iron, as observed here. The calculated nucleosynthetic yields from Type Ib and II SNs are shown to be qualitatively inconsistent with the data. We conclude that the SNs which produced these remnants were of Type Ia. This finding also confirms earlier suggestions that the class of Balmer-dominated remnants arise from Type Ia SN explosions. Based on these early results from the LMC SNR sample, we find that roughly one-half of the SNRs produced in the LMC within the last approximately 1500 yr came from Type Ia SNs.

  15. 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.

  16. 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.

  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 miniProds using for instance a set of usual statistical operators (mean, median, rms, ...), fully extensible and applicable to any variable of a dataset. These metrics are stored in a fast search engine, queryable by humans and automated applications. * reporting or alerting, based on user-defined inference rules, through various media (emails, twitter feeds,..) and devices (phones, tablets). * analysing miniProds and metrics through a web interface allowing to dig into this base of information and extracting useful knowledge through multidimensional interactive display functions (time series, scatterplots, histograms, maps). The services provided by felyx will be generic, deployable at users own premises and adaptable enough to integrate any kind of parameters. Users will be able to operate their own felyx instance at any location, on datasets and parameters of their own interest, and the various instances will be able to interact with each other, creating a web of felyx systems enabling aggregation and cross comparison of miniProds and metrics from multiple sources. Initially two instances will be operated simultaneously during a 6 months demonstration phase, at IFREMER - on sea surface temperature (for GHRSST community) and ocean waves datasets - and PML - on ocean colour. We will present results from the Felyx project, demonstrate how the GHRSST community can exploit Felyx and demonstrate how the wider community can make use of the GHRSST data within Felyx.

  18. 2014 American Geophysical Union. All rights reserved. Observations and Numerical Simulations of Large Eddy Circulation

    E-print Network

    Pierce, Stephen

    into rolls aligned with the wind and/or near-surface current · Large eddy simulations showed similar features of Large Eddy Circulation in the Ocean Surface Mixed Layer Miles A. Sundermeyer1* , Eric Skyllingstad2. Rodney French Blvd., New Bedford, MA 02744-1221, USA. (msundermeyer@umassd.edu) Running Title: Large Eddy

  19. Propagation of circular polarized light in a scattering medium influenced by optical clearing

    Microsoft Academic Search

    Callum MacDonald; Igor Meglinski

    2011-01-01

    In the current report an approach of probing a scattering turbid medium with the back-scattered circular polarized light is presented. Circular polarization survives more scattering events than the direction of its propagation, whereas the helicity of backscattered optical radiation depends noticeably on the size of scattering particles. We demonstrate that the helicity flip of circular polarized light can be observed

  20. Comparison of H-alpha synoptic charts with the large-scale solar magnetic field as observed at Stanford

    NASA Technical Reports Server (NTRS)

    Duvall, T. L., Jr.; Wilcox, J. M.; Svalgaard, L.; Scherrer, P. H.; Mcintosh, P. S.

    1977-01-01

    Two methods of observing the neutral line of the large-scale photospheric magnetic field are compared: neutral line positions inferred from H-alpha photographs (McIntosh and Nolte, 1975) and observations of the photospheric magnetic field made with low spatial resolution (three minutes) and high sensitivity using the Stanford magnetograph. The comparison is found to be very favorable.

  1. Deep Australia Telescope Large Area Survey Radio Observations of the European Large Area ISO Survey S1/Spitzer Wide-Area Infrared Extragalactic Field

    NASA Astrophysics Data System (ADS)

    Middelberg, Enno; Norris, Ray P.; Cornwell, Tim J.; Voronkov, Maxim A.; Siana, Brian D.; Boyle, Brian J.; Ciliegi, Paolo; Jackson, Carole A.; Huynh, Minh T.; Berta, Stefano; Rubele, Stefano; Lonsdale, Carol J.; Ivison, Rob J.; Smail, Ian

    2008-04-01

    We have conducted sensitive (1 ? < 30 ?Jy) 1.4 GHz radio observations with the Australia Telescope Compact Array of a field largely coincident with infrared observations of the Spitzer Wide-Area Extragalactic Survey. The field is centered on the European Large Area ISO Survey S1 region and has a total area of 3.9°. We describe the observations and calibration, source extraction, and cross-matching to infrared sources. Two catalogs are presented: one of the radio components found in the image and another of radio sources with counterparts in the infrared and extracted from the literature. 1366 radio components were grouped into 1276 sources, 1183 of which were matched to infrared sources. We discover 31 radio sources with no infrared counterpart at all, adding to the class of Infrared-Faint Radio Sources.

  2. 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.; Filipovi?, 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 observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.

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

    NASA Astrophysics Data System (ADS)

    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.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Enoto, T.; Falletti, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fukazawa, Y.; Fukui, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hayashi, K.; Horan, D.; Hou, X.; Hughes, R. E.; Jackson, M. S.; Jóhannesson, G.; Johnson, A. S.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Lee, S.-H.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Makishima, K.; Mazziotta, M. N.; Mehault, J.; Mitthumsiri, W.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Nishino, S.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Orienti, M.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Razzano, M.; Reimer, A.; Reimer, O.; Roth, M.; Sadrozinski, H. F.-W.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Strong, A. W.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Tibolla, O.; Tinivella, M.; Torres, D. F.; Tramacere, A.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Zimmer, S.

    2012-09-01

    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 ~100 MeV and ~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 ~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 CO) at a 1° × 1° pixel level. The correlation is found to be linear over a W CO range of ~10-fold when divided in three regions, suggesting penetration of nuclear CRs to most of the cloud volumes. The W CO-to-mass conversion factor, X CO, is found to be ~2.3 × 1020 cm-2(K km s-1)-1 for the high-longitude part of Orion A (l > 212°), ~1.7 times higher than ~1.3 × 1020 found for the rest of Orion A and B. We interpret the apparent high X 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 CO decreases faster than the H2 column density in the region making the gas "darker" to W CO.

  4. Circular asymmetric Helmholtz resonators

    PubMed

    Selamet; Ji

    2000-05-01

    A three-dimensional (3D) analytical approach is developed to account for the nonplanar wave propagation in the cavity and neck of "piston-driven" circular asymmetric Helmholtz resonators. The present 3D analytical results are compared with (1) the numerical predictions from the boundary element method (BEM) to evaluate the analytical approach; and (2) the one-dimensional (1D) solution to examine the effect of nonplanar waves at area discontinuity between the neck and the cavity. In order to improve the 1D solution, the end correction is also determined by using the 3D analytical approach. The effect of neck offset on the resonance frequency of circular asymmetric Helmholtz resonators is investigated. Predictions of resonance frequency and transmission loss from the present 3D and corrected 1D analytical approaches are, respectively, identical and close to the BEM results, while the corrected 1D approach provides a better accuracy compared to the 1D solutions with Ingard's correction. Finally, the boundary element method is employed to determine the wave attenuation performance of the "pipe-mounted" Helmholtz resonators to examine the effect of multidimensional waves in the vicinity of the main duct and neck junction. PMID:10830358

  5. Simple Circular Motion Model

    NSDL National Science Digital Library

    2012-01-15

    This simulation is a simple model of rides like an amusement park Merry-Go-Round. The rotational speed and radial distance are controlled with sliders at the bottom of the applet, while net horizontal force on the riders is monitored in the accompanying graph in terms of g-force experienced by riders. The 3D formatting allows viewing from a variety of vantage points. Students discover how rotational speed and radial distance interact to create a more thrilling ride. Don't miss the page link to "Physiological impact of g-forces". Students will learn that setting the speed and radial distance at the highest points will result in g-forces that exceed space shuttle re-entry and fighter jets at high speed. See Related Materials for an interactive tutorial on circular motion, appropriate for high school and lower-level undergraduate studies. The Simple Circular Motion Model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the jar file will run the program if Java is installed.

  6. Gravity field determination for Mars Observer

    Microsoft Academic Search

    Pasquale B. Esposito; Stuart Demcak; Duane Roth

    1990-01-01

    Mars Observer will be the first near circular, low altitude and short-periodic orbiter of Mars. From previous Mars orbiters, such as Mariner 9 and Vikings 1 and 2, a large gravitational oblateness and in general a gravity field ten times stronger than the earth's field have been determined. Because of these, the gravity field will dominate the evolution of the

  7. 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. PMID:10642198

  8. Large-scale patterns on the Sun observed in the millimetric wavelength range

    Microsoft Academic Search

    B. Vrsnak; S. Pohjolainen; S. Urpo; H. Terasranta; R. Brajsa; V. Ruždjak; Z. Mouradian; S. Jurac

    1992-01-01

    The nature and behaviour of large-scale patterns on the solar surface, indicated by the areas of brightness-temperature depressions in the millimetric wavelength range, is studied. A large sample of 346 individual, low-temperature regions (LTRs) was employed to provide reliable statistical evidence. An association of 99% was found between the locations of LTRs and the large-scale magnetic field inversion lines, and

  9. Loop equation analysis of the circular ? ensembles

    NASA Astrophysics Data System (ADS)

    Witte, N. S.; Forrester, P. J.

    2015-02-01

    We construct a hierarchy of loop equations for invariant circular ensembles. These are valid for general classes of potentials and for arbitrary inverse temperatures Re ? > 0 and number of eigenvalues N. Using matching arguments for the resolvent functions of linear statistics f( ?) = ( ? + z)/( ? - z) in a particular asymptotic regime, the global regime, we systematically develop the corresponding large N expansion and apply this solution scheme to the Dyson circular ensemble. Currently we can compute the second resolvent function to ten orders in this expansion and also its general Fourier coefficient or moment mk to an equivalent length. The leading large N, large k, k/ N fixed form of the moments can be related to the small wave-number expansion of the structure function in the bulk, scaled Dyson circular ensemble, known from earlier work. From the moment expansion we conjecture some exact partial fraction forms for the low k moments. For all of the forgoing results we have made a comparison with the exactly soluble cases of ? = 1, 2, 4, general N and even, positive ?, N = 2, 3.

  10. Explanation of recent observations of very large electromagnetic dissociation cross sections. II. Higher order corrections

    Microsoft Academic Search

    John W. Norbury; Gerhard Baur

    1993-01-01

    Hill, Wohn, Schwellenbach, and Smith have recently measured very large electromagnetic dissociation cross sections in the collisions of very heavy nuclei. Weizsacker-Williams (WW) theory predicts that these cross sections should be even larger. It has recently been shown that WW theory fails for these reactions because the associated probabilities are too large. However, WW theory is based on first order

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

    SciTech Connect

    Devine, K. E.; Churchwell, E. [Department of Astronomy, University of Wisconsin, 475 N. Charter Street, Madison, WI 53703 (United States); Chandler, C. J.; Borg, K. J. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Brogan, C.; Indebetouw, R. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Shirley, Y., E-mail: kdevine@collegeofidaho.edu [Steward Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States)

    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.

  12. Elliptical vs Circular Orbit

    NSDL National Science Digital Library

    Bob Urschel

    Find the contrast between a highly exaggerated earth elliptical orbit and circular orbit depicted in .mov format. It should be mentioned to students that in reality the earth's elliptical orbit around the sun would hardly be noticeable if viewed from this distance. Taken alone, the video could unfortunately perpetuate the misconception that earth sun distance is responsible for the seasons. Still, the video is useful for pointing out that the earth's speed around the sun is not constant, with the earth moving fastest in January and slowest in July. This phenomenon helps explain why summer is longer in the Northern Hemisphere and for the analemma. The animation can be paused and rewound to emphasize important points.

  13. Condensation of circular DNA.

    PubMed

    Starostin, E L

    2013-04-28

    A simple model of a circularly closed double-stranded DNA in a poor solvent is considered as an example of a semi-flexible polymer with self-attraction. To find the ground states, the conformational energy is computed as a sum of the bending and torsional elastic components and the effective self-attraction energy. The model includes a relative orientation or sequence dependence of the effective attraction forces between different pieces of the polymer chain. Two series of conformations are analysed: a multicovered circle (a toroid) and a multifold two-headed racquet. The results are presented as a diagram of state. It is suggested that the stability of particular conformations may be controlled by proper adjustment of the primary structure. Application of the model to other semi-flexible polymers is considered. PMID:23635167

  14. Circularly polarized microstrip antennas

    NASA Technical Reports Server (NTRS)

    Lo, Y. T.; Engst, B.; Lee, R. Q. H.

    1985-01-01

    A simple microstrip antenna can be made to radiate EM waves of any polarization, in particular, the circular polarization (CP) without any phasing network and power divider. A simple and accurate theory for this family of antennas was developed. However, the CP bandwidth, (CPBW) the bandwidth in which the axial ratio (AR) is less than a certain specified value, is very small. Most of the experimental designs were made for a feed placed along the diagonal of the patch. It is shown that there are practically infinitely many possible designs with different feed location. The speculation that other designs might give a wider bandwidth is clarified and an effective method for broadening the bandwidth is shown.

  15. 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.

  16. Experimental Observation of Large Guided Acoustic Wave Brillouin Scattering in Photonic Crystal Fibres

    Microsoft Academic Search

    Jean Charles Beugnot; Thibaut Sylvestre; Herve Maillotte; Gilles Melin; Vincent Laude

    2006-01-01

    We experimentally show the existence of large and isolated guided acoustic wave Brillouin scattering (GAWBS) modes in various photonic crystal fibres which are numerically identified with fundamental longitudinal phonon modes of the solid core.

  17. A Circular Po Rectangular R

    E-print Network

    Leung, Ka-Cheong

    of Electronic Science and Technology of China Chengdu, Sichuan, China, 611731 liyaanem@gmail.com Abstract--In this paper, a compact hybrid-integ rectangular ring antenna with circular polariz for RFID reader. By integrating a cross-slotted p a rectangular ring antenna in the same plan antenna has the features of circular

  18. Terahertz Circular Photonic Crystal Fiber

    Microsoft Academic Search

    Liang Wang; Dongxiao Yang; Yin Chen; Zhineng Li

    2006-01-01

    Terahertz (THz) circular photonic crystal fiber (CPCF) with the similar distribution of air holes as that in variable-size circular photonic crystal in polyethylene material was introduced. Guiding and dispersion properties of the CPCF with different parameters have been accurately computed. Results show that the CPCF is a useful terahertz waveguide which has good ability to confine THz fields, low group-velocity

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

    Microsoft Academic Search

    M. Ajello; L. Baldini; G. Barbiellini; D. Bastieri; K. Bechtol; R. Bellazzini; B. Berenji; E. D. Bloom; E. Bonamente; A. W. Borgland; J. Bregeon; M. Brigida; P. Bruel; R. Buehler; S. Buson; G. A. Caliandro; R. A. Cameron; P. A. Caraveo; J. M. Casandjian; C. Cecchi; E. Charles; A. Chekhtman; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; J. Conrad; S. Cutini; A. de Angelis; F. de Palma; C. D. Dermer; E. do Couto e Silva; P. S. Drell; A. Drlica-Wagner; T. Enoto; C. Favuzzi; S. J. Fegan; E. C. Ferrara; Y. Fukazawa; P. Fusco; F. Gargano; D. Gasparrini; S. Germani; N. Giglietto; F. Giordano; M. Giroletti; T. Glanzman; G. Godfrey; P. Graham; I. A. Grenier; S. Guiriec; M. Gustafsson; D. Hadasch; M. Hayashida; R. E. Hughes; A. S. Johnson; T. Kamae; H. Katagiri; J. Kataoka; J. Knödlseder; M. Kuss; J. Lande; L. Latronico; A. M. Lionetto; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; M. N. Mazziotta; P. F. Michelson; W. Mitthumsiri; T. Mizuno; C. Monte; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Murgia; J. P. Norris; E. Nuss; T. Ohsugi; A. Okumura; E. Orlando; J. F. Ormes; M. Ozaki; D. Paneque; M. Pesce-Rollins; M. Pierbattista; F. Piron; G. Pivato; S. Rainò; M. Razzano; S. Ritz; M. Roth; P. M. Saz Parkinson; J. D. Scargle; T. L. Schalk; C. Sgrò; E. J. Siskind; G. Spandre; P. Spinelli; D. J. Suson; H. Tajima; H. Takahashi; T. Tanaka; J. G. Thayer; J. B. Thayer; L. Tibaldo; M. Tinivella; D. F. Torres; E. Troja; Y. Uchiyama; T. L. Usher; J. Vandenbroucke; V. Vasileiou; G. Vianello; V. Vitale; A. P. Waite; B. L. Winer; K. S. Wood; M. Wood; Z. Yang; S. Zimmer

    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

  20. Large Fields of Sub-circular Depressions On The Carnegie Ridge Flanks Discovered During The French German Salieri Cruise (r/v Sonne, 22-08/16-09 2001)

    NASA Astrophysics Data System (ADS)

    Michaud, F.; Collot, J. Y.; Gutscher, M. A.; Charvis, P.; Flüh, E.; Santana, E.

    During the SALIERI Cruise offshore Ecuador, multibeam bathymetry was collected with the Simrad EM120 of the R/V SONNE. The most conspicuous features discov- ered on the Carnegie Ridge are fields of circular closed depressions distributed along the mid-slope of the ridge northern and southern flanks at depths of 1500 to 2600 m. These circular depressions are 1-4 km wide and typically 100-300 m deep. Most are flat floored and some are so densely packed that they look like a honeycomb pattern. Mud penetrator data indicate that the depressions were carved into the ridge sedimen- tary blanket, although the influence of pre-existing topography in the volcanic base- ment cannot be excluded. On the mid-slope of the southern flank more than 400 m of nannofossil chalk ooze and chalk dated from upper Miocene to upper Pleistocene were recovered at Site 157 of DSDP 16 indicating that the depressions formed in these calcareous deposits. From conventional bathymetry, these circular depressions were previously identified as canyons and gullies and the hypothesis of their erosional origin in relation to either a past emergence of the ridge or bottom currents was first proposed by van Andel et al. (1971) (van Andel et al., 1973). Although we cannot exclude the effects of currents to produce sub-circular depressions, other alternatives including both marine and subaerial karstic origins will be discussed. Van Andel et al., 1971,Tectonics of the Panama Basin, Bull. Geol. Soc. Am., 82 (6) 1489. Van Andel et al., 1973, DSDP 16, Site 157, pp. 53-150.

  1. 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

    SciTech Connect

    Giallongo, E.; Menci, N.; Grazian, A.; Gallozzi, S.; Castellano, M.; Fiore, F.; Fontana, A.; Pentericci, L.; Boutsia, K.; Paris, D.; Speziali, R.; Testa, V. [INAF—Osservatorio Astronomico di Roma, via di Frascati 33, I-00040 Monteporzio (Italy)

    2014-01-20

    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 emissivity in broad agreement with the measured ICL fraction. The present analysis shows that the measure of the ICL fraction in clusters can quantitatively account for the stellar stripping activity in their cores and can be used to probe their CDM distribution and evolutionary status.

  2. Circular chemiresistors for microchemical sensors

    DOEpatents

    Ho, Clifford K. (Albuquerque, NM)

    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.

  3. On the determination of polarization observables in proton-induced reactions using large-acceptance magnetic spectrometers

    NASA Astrophysics Data System (ADS)

    Hannen, V. M.; Bassini, R.; van den Berg, A. M.; Blasi, N.; De Frenne, D.; De Leo, R.; Ellinghaus, F.; Frekers, D.; Hagemann, M.; Harakeh, M. N.; Henderson, R.; Heyse, J.; de Huu, M. A.; Jacobs, E.; Krüsemann, B. A. M.; Rakers, S.; Schmidt, R.; Sohlbach, H.; Wörtche, H. J.

    2003-03-01

    For proton-induced reactions, a formalism is presented to determine polarization observables using a focal-plane polarimeter in combination with a large-acceptance spectrometer, where also the effect of the scattering in the non-dispersive plane of the spectrometer is taken into account. The inclusive proton-carbon analyzing power needed for the determination of spin observables was studied over a wide angular range and a new parameterization for this quantity was deduced.

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

    SciTech Connect

    Shuifer, M. I.; Argal, E. S. [JSC 'SPII Gidroproekt' (Russian Federation)

    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.

  5. NEAR-INFRARED CIRCULAR POLARIZATION IMAGES OF NGC 6334-V

    SciTech Connect

    Kwon, Jungmi; Tamura, Motohide; Hashimoto, Jun; Kusakabe, Nobuhiko; Kandori, Ryo [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Lucas, Phil W.; Hough, James H. [Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB (United Kingdom); Nakajima, Yasushi [Center of Information and Communication Technology, Hitotsubashi University, 2-1 Naka, Kunitachi, Tokyo 186-8601 (Japan); Nagayama, Takahiro [Department of Astrophysics, Nagoya University, Nagoya 464-8602 (Japan); Nagata, Tetsuya, E-mail: jungmi.kwon@nao.ac.jp [Department of Astronomy, Kyoto University, Kyoto 606-8502 (Japan)

    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.

  6. Radar Observation of Large Attenuation in Convective Storms: Implications for the Dropsize Distribution

    NASA Technical Reports Server (NTRS)

    Tian, Lin; Heymsfield, G. M.; Srivastava, R. C.

    2000-01-01

    Airborne meteorological radars typically operate at attenuating wavelengths. The path integrated attenuation (PIA) can be estimated using the surface reference technique (SRT). In this method, an initial value is determined for the radar cross section of the earth surface in a rain-free area in relatively close proximity to the rain cloud. During subsequent observations of precipitation any decrease 'in the observed surface cross section from the reference value s assumed to be a result of the two-way attenuation along the propagation path. In this paper we present selected instances of high PIA observed over land by an airborne radar. The observations were taken in Brazil and Florida during TRMM (Tropical Rainfall Measurement Mission) field campaigns. We compared these observations with collocated and nearly simultaneous ground-based radar observations by an S-band radar that is not subject to significant attenuation. In this preliminary evaluation, a systematic difference in the attenuation in the two storms is attributed to a difference in the raindrop size distributions; this is supported by observations of ZDR (differential reflectivity).

  7. Observation of the Earth's dynamic ellipticity with a large ring laser gyroscope

    NASA Astrophysics Data System (ADS)

    Tian, Wei; Schreiber, Karl Ulrich; Kluegel, Thomas; Gebauer, Andre

    2015-04-01

    With the rapid advance of large ring laser gyroscopes, their promising applications in geoscience (such as, detection of Earth's tides, Earth's free oscillations and seismical waves etc.) have been demonstrated impressively by several ring laser groups. In this work we will report on one more application, which is the determination of the Earth's dynamical ellipticity by measuring the retrograde diurnal polar motion at the K1 wave with a single large ring laser. The Earth's astronomical dynamical ellipticity Hd = 0.00325(6) is estimated by means of 168 days of continuous data from the G-ring, located in Wettzell, Germany, which is the most stable one amongst the currently running large ring laser gyroscopes.

  8. Explanation of recent observations of very large electromagnetic dissociation cross sections. II. Higher order corrections

    NASA Astrophysics Data System (ADS)

    Norbury, John W.; Baur, Gerhard

    1993-10-01

    Hill, Wohn, Schwellenbach, and Smith have recently measured very large electromagnetic dissociation cross sections in the collisions of very heavy nuclei. Weizsacker-Williams (WW) theory predicts that these cross sections should be even larger. It has recently been shown that WW theory fails for these reactions because the associated probabilities are too large. However, WW theory is based on first order perturbation theory and an electric dipole approximation. Calculations are presented which show that for those cases where WW theory and experiment disagree, higher order perturbation plus electric quadrupole corrections improve the agreement between theory and experiment. These corrections also imply that multiple electromagnetic excitations occur.

  9. Interpreting observed northern hemisphere snow trends with large ensembles of climate simulations

    E-print Network

    for Atmospheric Research's Community Earth System Model. Two 40-member ensembles driven by historical radiative for Atmospheric Research's Community Earth System Model (CCSM4), in comparison with observations. Each ensemble

  10. Do recent observations of very large electromagnetic dissociation cross sections signify a transition towards non-perturbative QED?

    Microsoft Academic Search

    John W. Norbury

    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

  11. Added discussion of ``Observations of fast anisotropic ion heating, ion cooling, and ion recycling in large-amplitude drift waves''

    Microsoft Academic Search

    S. J. Sanders; R. F. Boivin; P. M. Bellan; R. A. Stern

    1999-01-01

    A recent paper [S. J. Sanders, P. M. Bellan, and R. A. Stern, Phys. Plasmas 5, 716, (1998)] identified neutral particle recycling as one important aspect of severe heating and cooling cycles observed in large-amplitude drift waves. An apparent inconsistency in the ionization mean free path of these neutrals, left as an open question in the original paper, is resolved

  12. Added discussion of “Observations of fast anisotropic ion heating, ion cooling, and ion recycling in large-amplitude drift waves”

    Microsoft Academic Search

    S. J. Sanders; R. F. Boivin; P. M. Bellan; R. A. Stern

    1999-01-01

    A recent paper [S. J. Sanders, P. M. Bellan, and R. A. Stern, Phys. Plasmas 5, 716, (1998)] identified neutral particle recycling as one important aspect of severe heating and cooling cycles observed in large-amplitude drift waves. An apparent inconsistency in the ionization mean free path of these neutrals, left as an open question in the original paper, is resolved

  13. ATLAS: Australia Telescope Large Area Survey: Deep Radio Observations of the CDFS-SWIRE and ELAIS-S1 fields

    E-print Network

    Norris, Ray

    ATLAS: Australia Telescope Large Area Survey: Deep Radio Observations of the CDFS-SWIRE and ELAIS: University of Durham, UK. GOODS The Australia Telescope Compact Array used to make the radio images-S1 fields 1. Overview · We are imaging the CDFS and ELAIS-S1 SWIRE fields at 20 cm. Combining radio

  14. Interplanetary Shock Waves and Large-Scale Structures: Ulysses' Observations in and out of the Ecliptic Plane

    NASA Technical Reports Server (NTRS)

    Gonzalez-Esparza, J. A.; Balogh, A.; Forsyth, R. J.; Neugebauer, M.; Smith, E. J.; Phillips, J. L.

    1995-01-01

    A study is presented of 153 fast shock waves and their relation to other large-scale features in the solar wind: corotating interaction regions (CIRs), interplanetary counterparts of coronal mass ejections (ICMEs) and the magnetic sector structure, observed by Ulysses from October 1990 to the south solar pass in the summer of 1994.

  15. Observations on Physiology and Symbiosis of the Large Benthic Foraminiferan Operculina Ammonoides from the Gulf of Eilat

    E-print Network

    Simon, Emmanuel

    Observations on Physiology and Symbiosis of the Large Benthic Foraminiferan Operculina Ammonoides. Their symbiosis, calcification physiology, and ecological response to environmental changes are poorly understood that calcification is increasing in fed individuals. These data suggest that the symbiosis in LBF is quite different

  16. The large solar vacuum telescope: The optical system, and first spectral observations

    Microsoft Academic Search

    V. I. Skomorovsky; N. M. Firstova

    1996-01-01

    The performance of the optics of the Large Solar Vacuum Telescope (LSVT) and examples of the spectrograms taken with the spectrograph are presented. A new pneumo-mechanical support system for the siderostat mirror and monitoring system of the telescope optics is described.

  17. Observed Relationships Between Large-Scale Atmospheric Variability and the Carbon Cycle

    Microsoft Academic Search

    A. K. Hawes; D. W. Thompson

    2005-01-01

    The impact of increasing atmospheric carbon dioxide on global climate change has been studied extensively, but the effect of large-scale patterns of atmospheric variability on biogeochemical cycling has received substantially less attention. In this study, we examine the impact of two such patterns of atmospheric variability, the so-called Northern and Southern Annular Modes, on monthly and daily mean concentrations of

  18. 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." PMID:12289626

  19. Inference of 3-dimensional structure underlying large-scale coronal events observed by Yohkoh and Ulysses

    NASA Technical Reports Server (NTRS)

    Slater, G. L.; Freeland, S. L.; Hoeksema, T.; Zhao, X.; Hudson, H. S.

    1995-01-01

    The Yohkoh/SXT images provide full-disk coverage of the solar corona, usually extending before and after one of the large-scale eruptive events that occur in the polar crown These produce large arcades of X-ray loops, often with a cusp-shaped coronal extension, and are known to be associated with coronal mass ejections. The Yohkoh prototype of such events occurred 12 Nov. 1991. This allows us to determine heights from the apparent rotation rates of these structures. In comparison v with magnetic-field extrapolations from Wilcox Solar Observatory. use use this tool to infer the three dimensional structure of the corona in particular cases: 24 Jan. 1992, 24 Feb. 1993, 14 Apr. 1994, and 13 Nov. 1994. The last event is a long-duration flare event.

  20. 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.

  1. Pioneer and Voyager observations of the solar wind at large heliocentric distances and latitudes

    NASA Technical Reports Server (NTRS)

    Gazis, P. R.; Mihalov, J. D.; Barnes, A.; Lazarus, A. J.; Smith, E. J.

    1989-01-01

    Data obtained from the electrostatic analyzers aboard the Pioneer 10 and 11 spacecraft and from the Faraday cup aboard Voyager 2 were used to study spatial gradients in the distant solar wind. Prior to mid-1985, both spacecraft observed nearly identical solar wind structures. After day 150 of 1985, the velocity structure at Voyager 2 became flatter, and the Voyager 2 velocities were smaller than those observed by Pioneer 11. It is suggested that these changes in the solar wind at low latitudes may be related to a change which occurred in the coronal hole structure in early 1985.

  2. 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.

  3. Observations of large fluxes of He/+/ in the solar wind following an interplanetary shock

    NASA Technical Reports Server (NTRS)

    Gosling, J. T.; Asbridge, J. R.; Bame, S. J.; Feldman, W. C.; Zwickl, R. D.

    1980-01-01

    Los Alamos Scientific Laboratory instrumentation on Imp 7 has detected large fluxes of He(+) within that volume of solar wind plasma believed to be the solar ejecta driving the interplanetary shock wave disturbance of July 29, 1977. The very high He(+)/He(++) abundance ratio of 0.3 measured during this event suggests that this was solar prominence material only partially ionized by its passage through the corona.

  4. Herschel Observations of a Newly Discovered UX Ori Star in the Large Magellanic Cloud

    Microsoft Academic Search

    Geoffrey C. Clayton; B. Sargent; M. L. Boyer; B. A. Whitney; Jacco Th. van Loon; M. Meixner; P. Tisserand; C. Engelbracht; S. Hony; R. Indebetouw; K. A. Misselt; K. Okumura; P. Panuzzo; J. Roman-Duval; M. Sauvage; J. M. Oliveira; M. Sewilo; E. Churchwell

    2010-01-01

    The LMC star, SSTISAGE1C J050756.44-703453.9, was first noticed during a survey of EROS-2 light curves for stars with large irregular brightness variations typical of the R Coronae Borealis (RCB) class. However, the visible spectrum showing emission lines including the Balmer and Paschen series as well as many Fe II lines is emphatically not that of an RCB star. This star

  5. Experimental control of microdynamic events observed during the testing of a large deployable optical structure

    Microsoft Academic Search

    Ruth L. Moser; R. Scott Erwin; Karl N. Schrader; Kevin D. Bell; Steven F. Griffin; Michael K. Powers

    2000-01-01

    This paper presents experimental results relating to the Air Force Research Laboratory Precision Deployable Optics System (PDOS) ground demonstration. The PDOS experiment represents a sub-scale experimental test-bed for the demonstration of science and technology related to a large-aperture deployable space-based telescope systems. A description of the experimental test-bed is included. A description of microdynamic phenomena, referred to as `events' or

  6. Fermi Large Area Telescope Observations of Markarian 421: The Missing Piece of its Spectral Energy Distribution

    Microsoft Academic Search

    A. A. Abdo; M. Ackermann; M. Ajello; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; K. Bechtol; R. Bellazzini; B. Berenji; R. D. Blandford; E. D. Bloom; E. Bonamente; A. W. Borgland; A. Bouvier; J. Bregeon; A. Brez; M. Brigida; P. Bruel; R. Buehler; S. Buson; G. A. Caliandro; R. A. Cameron; A. Cannon; P. A. Caraveo; S. Carrigan; J. M. Casandjian; E. Cavazzuti; C. Cecchi; Ö. Çelik; E. Charles; A. Chekhtman; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; J. Conrad; S. Cutini; A. de Angelis; F. de Palma; C. D. Dermer; E. do Couto e. Silva; P. S. Drell; R. Dubois; D. Dumora; L. Escande; C. Favuzzi; S. J. Fegan; J. Finke; W. B. Focke; P. Fortin; M. Frailis; L. Fuhrmann; Y. Fukazawa; T. Fukuyama; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Gehrels; M. Georganopoulos; S. Germani; B. Giebels; N. Giglietto; P. Giommi; F. Giordano; M. Giroletti; T. Glanzman; G. Godfrey; I. A. Grenier; S. Guiriec; D. Hadasch; M. Hayashida; E. Hays; D. Horan; R. E. Hughes; G. Jóhannesson; A. S. Johnson; W. N. Johnson; M. Kadler; T. Kamae; H. Katagiri; J. Kataoka; J. Knödlseder; M. Kuss; J. Lande; L. Latronico; S.-H. Lee; F. Longo; F. Loparco; B. Lott; M. N. Lovellette; P. Lubrano; G. M. Madejski; A. Makeev; W. Max-Moerbeck; M. N. Mazziotta; J. E. McEnery; J. Mehault; P. F. Michelson; W. Mitthumsiri; T. Mizuno; C. Monte; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Murgia; T. Nakamori; M. Naumann-Godo; S. Nishino; P. L. Nolan; J. P. Norris; E. Nuss; T. Ohsugi; A. Okumura; N. Omodei; E. Orlando; J. F. Ormes; M. Ozaki; D. Paneque; J. H. Panetta; D. Parent; V. Pavlidou; T. J. Pearson; V. Pelassa; M. Pepe; M. Pesce-Rollins; M. Pierbattista; F. Piron; T. A. Porter; S. Rainò; R. Rando; M. Razzano; A. Readhead; A. Reimer; O. Reimer; L. C. Reyes; J. L. Richards; S. Ritz; M. Roth; H. F.-W. Sadrozinski; D. Sanchez; A. Sander; C. Sgrò; E. J. Siskind; P. D. Smith; G. Spandre; P. Spinelli; L. Stawarz; M. Stevenson; M. S. Strickman; D. J. Suson; H. Takahashi; T. Takahashi; T. Tanaka; J. G. Thayer; J. B. Thayer; D. J. Thompson; L. Tibaldo; D. F. Torres; G. Tosti; A. Tramacere; E. Troja; T. L. Usher; J. Vandenbroucke; V. Vasileiou; G. Vianello; N. Vilchez; V. Vitale; A. P. Waite; P. Wang; A. E. Wehrle; B. L. Winer; K. S. Wood; Z. Yang; Y. Yatsu; T. Ylinen; J. A. Zensus; M. Ziegler; J. Aleksic; L. A. Antonelli; P. Antoranz; M. Backes; J. A. Barrio; J. Becerra González; W. Bednarek; A. Berdyugin; K. Berger; E. Bernardini; A. Biland; O. Blanch; R. K. Bock; A. Boller; G. Bonnoli; P. Bordas; D. Borla Tridon; V. Bosch-Ramon; D. Bose; I. Braun; T. Bretz; M. Camara; E. Carmona; A. Carosi; P. Colin; E. Colombo; J. L. Contreras; J. Cortina; S. Covino; F. Dazzi; E. De Cea del Pozo; C. Delgado Mendez; B. De Lotto; M. De Maria; F. De Sabata; A. Diago Ortega; M. Doert; A. Domínguez; D. Dominis Prester; D. Dorner; M. Doro; D. Elsaesser; D. Ferenc; M. V. Fonseca; R. J. García López; M. Garczarczyk; M. Gaug; G. Giavitto; N. Godinovi; A. Herrero; D. Hildebrand; D. Höhne-Mönch; J. Hose; D. Hrupec; T. Jogler; S. Klepser; T. Krähenbühl; D. Kranich; J. Krause; A. La Barbera; E. Leonardo; E. Lindfors; S. Lombardi; M. López; E. Lorenz; P. Majumdar; E. Makariev; G. Maneva; N. Mankuzhiyil; K. Mannheim; L. Maraschi; M. Mariotti; M. Martínez; D. Mazin; M. Meucci; J. M. Miranda; R. Mirzoyan; H. Miyamoto; J. Moldón; A. Moralejo; D. Nieto; K. Nilsson; R. Orito; I. Oya; R. Paoletti; J. M. Paredes; S. Partini; M. Pasanen; F. Pauss; R. G. Pegna; M. A. Perez-Torres; M. Persic; J. Peruzzo; J. Pochon; F. Prada; P. G. Prada Moroni; E. Prandini; N. Puchades; I. Puljak; T. Reichardt; W. Rhode; M. Ribó; J. Rico; M. Rissi; S. Rügamer; A. Saggion; K. Saito; T. Y. Saito; M. Salvati; M. Sánchez-Conde; K. Satalecka; V. Scalzotto; V. Scapin; C. Schultz; T. Schweizer; M. Shayduk; S. N. Shore; A. Sierpowska-Bartosik; A. Sillanpää; J. Sitarek; D. Sobczynska; F. Spanier; S. Spiro; A. Stamerra; B. Steinke; J. Storz; N. Strah; J. C. Struebig; T. Suric; L. O. Takalo; F. Tavecchio; P. Temnikov; T. Terzic; D. Tescaro; M. Teshima; H. Vankov; R. M. Wagner; Q. Weitzel; V. Zabalza; F. Zandanel; R. Zanin; M. Villata; C. Raiteri; H. D. Aller; M. F. Aller; W. P. Chen; B. Jordan; E. Koptelova; O. M. Kurtanidze; A. Lähteenmäki; B. McBreen; V. M. Larionov; C. S. Lin; M. G. Nikolashvili; R. Reinthal; E. Angelakis; M. Capalbi; A. Carramiñana; L. Carrasco; P. Cassaro; A. Cesarini; A. Falcone; M. A. Gurwell; T. Hovatta; Yu. A. Kovalev; Y. Y. Kovalev; T. P. Krichbaum; H. A. Krimm; M. L. Lister; J. W. Moody; G. Maccaferri; Y. Mori; I. Nestoras; A. Orlati; C. Pace; C. Pagani; R. Pearson; M. Perri; B. G. Piner; E. Ros; A. C. Sadun; T. Sakamoto; J. Tammi; A. Zook

    2011-01-01

    We report on the gamma-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) gamma-ray spectrum above 0.3 GeV can be well described by a power-law function with photon index Gamma = 1.78 ±

  7. Large-Eddy Simulations and Observations of Atmospheric Marine Boundary Layers above Nonequilibrium Surface Waves

    Microsoft Academic Search

    Peter P. Sullivan; James B. Edson; Tihomir Hristov; James C. McWilliams

    2008-01-01

    Winds and waves in marine boundary layers are often in an unsettled state when fast-running swell generated by distant storms propagates into local regions and modifies the overlying turbulent fields. A large-eddy simulation (LES) model with the capability to resolve a moving sinusoidal wave at its lower boundary is developed to investigate this low-wind\\/fast-wave regime. It is used to simulate

  8. Observations of residual ULF signals from the Parkfield magnetometer surrounding large Earthquakes

    NASA Astrophysics Data System (ADS)

    Bortnik, J.; Cutler, J. W.; Dunson, C.; Bleier, T.

    2005-12-01

    We use long-term (1999-2004) ULF data (<10 Hz) from a triaxial search-coil magnetometer located in Parkfield, California, to construct signal statistical quantities parametrized according to time of day, frequency range, coil orientation, season, and geomagnetic activity (Kp index). For each such parameter bin, we compute statistical quantities such as mean, variance, median and quartiles of the magnetic signal, and use these quantities as the baseline values from which signals are assumed to deviate. We then examine time periods surrounding those of large, nearby Earthquakes, and subtract the average and median signal values from the absolute signal values to obtain signal `residues'. Results show that this technique can be effective in reducing large background variations and thereby increasing the signal to noise ratio (SNR), allowing much lower amplitude signals of local origin to be detected. To further increase the SNR, we superpose a number of large earthquake periods and discuss the results in light of possible seismogenic ULF signal sources.

  9. Observations and Implications of Large-amplitude Longitudinal Oscillations in a Solar Filament

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  10. Observations and Implications of Large-Amplitude LongitudinalOscillations in a Solar Filament

    NASA Astrophysics Data System (ADS)

    Karpen, Judith T.; Luna, Manuel; Knizhnik, Kalman J.; Muglach, Karin; Gilbert, Holly; Kucera, Therese A.; Uritsky, Vadim

    2014-06-01

    On 20 August 2010 an energetic disturbance triggered large-amplitude longitudinal oscillations in a large fraction of a nearby filament. The triggering mechanism appears to be episodic jets connecting the energetic event with the filament threads. We analyzed this periodic motion 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 homogeneity 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 also estimated the magnitude of the energy released in the nearby event by studying the dynamic response of the filament threads, and concluded that the initiating event is likely to be a microflare. We will present the results of this investigation and discuss their implications for filament structure and heating. This work was supported by NASA’s H-SR program.

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

    SciTech Connect

    Luna, M. [Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain); Knizhnik, K. [Department of Physics and Astronomy, The Johns Hopkins University, Maryland (United States); Muglach, K.; Karpen, J.; Gilbert, H.; Kucera, T. A.; Uritsky, V. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    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.

  12. Circular polarization survey of intermediate polars I. Northern targets in the range 17 h < RA < 23 h

    NASA Astrophysics Data System (ADS)

    Butters, O. W.; Katajainen, S.; Norton, A. J.; Lehto, H. J.; Piirola, V.

    2009-03-01

    Context: The origin, evolution, and ultimate fate of magnetic cataclysmic variables are poorly understood. It is largely the nature of the magnetic fields in these systems that leads to this poor understanding. Fundamental properties, such as the field strength and the axis alignment, are unknown in a majority of these systems. Aims: We undertake to put all the previous circular polarization measurements into context and systematically survey intermediate polars for signs of circular polarization, hence to get an indication of their true magnetic field strengths and try to understand the evolution of magnetic cataclysmic variables. Methods: We used the TurPol instrument at the Nordic Optical Telescope to obtain simultaneous UBVRI photo-polarimetric observations of a set of intermediate polars, during the epoch 2006 July 31-August 2. Results: Of this set of eight systems two (1RXS J213344.1+510725 and 1RXS J173021.5-055933) were found to show significant levels of circular polarization, varying with spin phase. Five others (V2306 Cyg, AO Psc, DQ Her, FO Aqr, and V1223 Sgr) show some evidence for circular polarization and variation of this with spin phase, whilst AE Aqr shows little evidence for polarized emission. We also report the first simultaneous UBVRI photometry of the newly identified intermediate polar 1RXS J173021.5-055933. Conclusions: Circular polarization may be ubiquitous in intermediate polars, albeit at a low level of one or two percent or less. It is stronger at longer wavelengths in the visible spectrum. Our results lend further support to the possible link between the presence of soft X-ray components and the detectability of circular polarization in intermediate polars. Based on observations obtained at the Nordic Optical Telescope at the Roque de los Muchachos Observatory in La Palma.

  13. How well does a 1\\/4° global circulation model simulate large-scale oceanic observations?

    Microsoft Academic Search

    Detlef Stammer; Robin Tokmakian; Albert Semtner; Carl Wunsch

    1996-01-01

    Numerical high-resolution ocean general circulation models have experienced a revolutionary development during the last decade. Today they are run globally in realistic configuration with realistic surface boundary forcing. To fully use the results of those models in understanding various aspects of the ocean general circulation and to combine ocean observations with models (state estimation) in a manner consistent with the

  14. Reply to Magnani et al.: Linking large-scale chlorophyll fluorescence observations with

    E-print Network

    Minnesota, University of

    of SIF observations to monitor crop photosynthesis (5) empirically demonstrates a strong linear statistical relationships between SIF and GPP best fits our global crop productiv- ity study (5). We feel with cropland gross primary production The derivation of the first global maps of sun-induced chlorophyll

  15. Large-scale enhancements in NO\\/NOy from subsonic aircraft emissions: Comparisons with observations

    Microsoft Academic Search

    Jacquelyn C. Witte; I. A. Folkins; J. Neima; B. A. Ridley; J. G. Walega; A. J. Weinheimer

    1997-01-01

    One of the DC-8 flights from the 1992 AASE 2 campaign flew south from Maine over the Atlantic Ocean, sampling air downstream of areas in the eastern United States associated with heavy air traffic. We use a photochemical trajectory model to help interpret observed NO\\/NOy ratios from the stratospheric portions of this flight. The model is run with and without

  16. Large-scale enhancements in NO\\/NO y from subsonic aircraft emissions: Comparisons with observations

    Microsoft Academic Search

    Jacquelyn C. Witte; I. A. Folkins; J. Neima; B. A. Ridley; J. G. Walega; A. J. Weinheimer

    1997-01-01

    One of the DC-8 flights from the 1992 AASE 2 campaign flew south from Maine over the Atlantic Ocean, sampling air downstream of areas in the eastern United States associated with heavy air traffic. We use a photochemical trajectory model to help interpret observed NO\\/NOu ratios from the stratospheric portions of this flight. The model is run with and without

  17. CARIBIC DOAS observations of nitrous acid and formaldehyde in a large convective cloud

    NASA Astrophysics Data System (ADS)

    Heue, K.-P.; Riede, H.; Walter, D.; Brenninkmeijer, C. A. M.; Wagner, T.; Frieß, U.; Platt, U.; Zahn, A.; Stratmann, G.; Ziereis, H.

    2013-09-01

    The CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) flying laboratory measures once per month the chemical composition at cruise altitude (10...12 km) during 4 consecutive Lufthansa flights. Here we present a case study of enhanced nitrogen oxides (NOx), nitrous acid (HONO), and formaldehyde (HCHO) in a thunderstorm cloud over the Caribbean islands of Guadeloupe in August 2011. Nitrous acid is an important reservoir gas for OH radicals, and only few observations of HONO at cruise altitude exist. CARIBIC is designed as a long period atmospheric observation system, the actual system has been flying almost monthly since 8 yr now. During this period only very few similar events (one since 2008) were observed. Due to multiple scattering the light path inside clouds is enhanced, thereby lowering the detection limit of the DOAS instrument. Under background conditions the detection limits are 46 ppt for HONO, 387 ppt for \\chem{HCHO}, and 100 ppt for NO2 and are roughly three times lower inside the cloud. Based on radiative transfer simulations we estimate the path length to 90{ldots}100 km and the cloud top height to ?15 km. The inferred mixing ratios of HONO, HCHO and NO2 are 37 ppt, 400 ppt and 170 ppt, respectively. Bromine monoxide (BrO) remained below the detection limit of 1 ppt. Because the uplifted air masses originated from the remote marine boundary layer and lightning was observed in the area by the World Wide Lightning Location Network several hours prior to the measurement, the NO (?1.5 ppb) enhancement was in all likelihood caused by lightning. The main source for the observed HCHO is probably updraught from the boundary layer, because the chemical formation of formaldehyde due to methane oxidation is too weak. Besides HCHO also CH3OOH and isoprene are considered as precursors. The chemical box model CAABA is used to estimate the \\chem{NO} and HCHO source strengths, which are necessary to explain our measurements. For NO a source strength of 8.25 × 109 molec cm-2 s-1 km-1 is found, which corresponds to the lightning activity as observed by the World Wide Lightning Location network and a lightning emission of 4.2 × 1025 NO molec/flash. The HCHO updraught is of the order of 121 × 109 molec cm-2 s-1 km-1. Also isoprene and CH3OOH as possible HCHO sources were studied and similar source strengths were found.

  18. Observations and Implications of Large-Amplitude Longitudinal Oscillations in a Solar Filament

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    On 20 August 2010 an energetic disturbance triggered large-amplitude longitudinal oscillations in a large fraction of a nearby filament. The triggering mechanism appears to be episodic jets connecting the energetic event with the filament threads. We analyzed this periodic motion 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 homogeneity 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 also estimated the magnitude of the energy released in the nearby event by studying the dynamic response of the filament threads, and concluded that the initiating event is likely to be a microflare. Using a nonlinear force-free field extrapolation of the photospheric magnetogram to estimate the coronal magnetic structure, we determined the possible connectivity between the jet source and the oscillating prominence segments. We will present the results of this investigation and discuss their implications for filament structure and heating. This work was supported by NASA's H-SR program.

  19. 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.

  20. 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. [W.W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Baldini, L.; Bellazzini, R.; Bregeon, J. [INFN — Sezione di Pisa, I-56127 Pisa (Italy); Barbiellini, G. [INFN — Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D.; Buson, S. [INFN — Sezione di Padova, I-35131 Padova (Italy); Bonamente, E.; Cecchi, C. [INFN — Sezione di Perugia, I-06123 Perugia (Italy); Brigida, M. [Dipartimento di Fisica 'M. Merlin' dell'Università e del Politecnico di Bari, I-70126 Bari (Italy); Bruel, P. [Laboratoire Leprince-Ringuet, École polytechnique, CNRS/IN2P3, Palaiseau (France); Caliandro, G.A. [Institut de Ciències de l'Espai (IEEE-CSIC), Campus UAB, 08193 Barcelona (Spain); Caraveo, P.A. [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, I-20133 Milano (Italy); Casandjian, J.M., E-mail: bijanb@alumni.stanford.edu, E-mail: elliott@slac.stanford.edu, E-mail: johann.cohen-tanugi@lupm.in2p3.fr [Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d'Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France); 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 ?? 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.

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

    SciTech Connect

    Cao Qinghong [High Energy Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637 (United States); Khalil, Shaaban [Centre for Theoretical Physics, British University in Egypt, El Sherouk City, Postal No. 11837, P.O. Box 43 (Egypt); Department of Mathematics, Ain Shams University, Faculty of Science, Cairo 11566 (Egypt); Ma, Ernest [Department of Physics and Astronomy, University of California, Riverside, California 92521 (United States); Okada, Hiroshi [Centre for Theoretical Physics, British University in Egypt, El Sherouk City, Postal No. 11837, P.O. Box 43 (Egypt)

    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.

  2. Do recent observations of very large electromagnetic dissociation cross sections signify a transition towards non-perturbative QED?

    NASA Astrophysics Data System (ADS)

    Norbury, John W.

    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).

  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 blazar 3C 279 occultations by the sun

    SciTech Connect

    Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D.; Buson, S. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bechtol, K.; Blandford, R. D.; Borgland, A. W.; Buehler, R.; Cameron, R. A.; Chiang, J. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Bellazzini, R.; Bregeon, J. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bruel, P. [Laboratoire Leprince-Ringuet, École polytechnique, CNRS/IN2P3, Palaiseau (France); Caliandro, G. A. [Institut de Ciències de l'Espai (IEEE-CSIC), Campus UAB, E-08193 Barcelona (Spain); Caraveo, P. A. [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, I-20133 Milano (Italy); Cavazzuti, E.; Ciprini, S. [Agenzia Spaziale Italiana (ASI) Science Data Center, I-00044 Frascati (Roma) (Italy); Cecchi, C. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Chaves, R. C. G. [Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d'Astrophysique, CEA Saclay, F-91191 Gif sur Yvette (France); Chekhtman, A. [Center for Earth Observing and Space Research, College of Science, George Mason University, Fairfax, VA 22030 (United States); Cheung, C. C., E-mail: imos@stanford.edu, E-mail: phdmitry@stanford.edu [National Research Council Research Associate, National Academy of Sciences, Washington, DC 20001 (United States); and others

    2014-04-01

    Observations of occultations of bright ?-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 ?3?, 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 ?-ray emission at a 3? confidence level.

  5. Fermi Large Area Telescope Observations of Blazar 3C 279 Occultations by the Sun

    NASA Astrophysics Data System (ADS)

    Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Blandford, R. D.; Borgland, A. W.; Bregeon, J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Chaves, R. C. G.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; D'Ammando, F.; de Angelis, A.; Dermer, C. D.; Digel, S. W.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Hayashida, M.; Hays, E.; Hughes, R. E.; Jackson, M. S.; Jogler, T.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Mazziotta, M. N.; Mehault, J.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Paneque, D.; Perkins, J. S.; Piron, F.; Pivato, G.; Prokhorov, D.; Rainò, S.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Ritz, S.; Romoli, C.; Sánchez-Conde, M.; Sanchez, D. A.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Takahashi, H.; Tanaka, T.; Tibaldo, L.; Tinivella, M.; Tosti, G.; Troja, E.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Winer, B. L.; Wood, K. S.; Yang, Z.

    2014-04-01

    Observations of occultations of bright ?-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 ?3?, 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 ?-ray emission at a 3? confidence level.

  6. Cover Image: USGS Circular 1381

    USGS Multimedia Gallery

    Cover image: USGS Circular 1381. View of Boulder Basin, Lake Mead, at sunset looking east. The flat topped mountain in the background is Fortification Hill, a well-known landmark in the viewshed from Hoover Dam....

  7. Large-area transition radiation detectors for cosmic-ray observations in space

    Microsoft Academic Search

    Dietrich Mueller; Edward Diehl; Florian Gahbauer; Peter Meyer; Simon Swordy

    1996-01-01

    The characteristic dependence of x-ray transition radiation on the Lorentz factor of the parent particle can be utilized in cosmic-ray observations on balloons or in space in order to discriminate between relativistic electrons and hadrons, or to determine the energy spectra of heavy cosmic-ray nuclei at very high energies. To obtain statistically meaningful results, exposure factors of the instruments of

  8. Very Large Baseline Array observations of Mrk 6: probing the jet-lobe connection

    NASA Astrophysics Data System (ADS)

    Kharb, P.; O'Dea, C. P.; Baum, S. A.; Hardcastle, M. J.; Dicken, D.; Croston, J. H.; Mingo, B.; Noel-Storr, J.

    2014-06-01

    We present the results of high-resolution VLBI (very long baseline interferometry) observations at 1.6 and 4.9 GHz of the radio-loud Seyfert galaxy, Mrk 6. These observations are able to detect a compact radio core in this galaxy for the first time. The core has an inverted spectral index (? ^{1.6}_{4.9} = +1.0 ± 0.2) and a brightness temperature of 1 × 108 K. Three distinct radio components, which resemble jet elements and/or hotspots, are also detected. The position angles of these elongated jet elements point not only to a curved jet in Mrk 6, but also towards a connection between the AGN and the kpc-scale radio lobes/bubbles in this galaxy. Firmer constraints on the star formation rate provided by new Herschel observations (SFR < 0.8 M? yr-1) make the starburst-wind-powered bubble scenario implausible. From plasma speeds, obtained via prior Chandra X-ray observations, and ram pressure balance arguments for the interstellar medium and radio bubbles, the north-south bubbles are expected to take 7.5 × 106 yr to form, and the east-west bubbles 1.4 × 106 yr. We suggest that the jet axis has changed at least once in Mrk 6 within the last ?107 yr. A comparison of the nuclear radio-loudness of Mrk 6 and a small sample of Seyfert galaxies with a subset of low-luminosity FR I radio galaxies reveals a continuum in radio properties.

  9. 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.

  10. MESSENGER orbital observations of large-amplitude Kelvin-Helmholtz waves at Mercury's magnetopause

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    We present a survey of Kelvin-Helmholtz (KH) waves at Mercury's magnetopause during MESSENGER's first Mercury year in orbit. The waves were identified on the basis of the well-established sawtooth wave signatures that are associated with nonlinear 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 subsonic, which implies that instability growth rates at Mercury's magnetopause 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 100 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 postnoon and duskside sectors of the magnetopause. This asymmetry is likely 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.

  11. Constraints on the Galactic Population of TEV Pulsar Wind Nebulae Using Fermi Large Area Telescope Observations

    E-print Network

    Acero, F; Ajello, M; Allafort, A; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Blandford, R D; Bloom, E D; Bonamente, E; Bottacini, E; Brandt, T J; Bregeon, 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 Palma, F; Dermer, C D; Di Venere, L; Silva, E do Couto e; Drell, P S; Drlica-Wagner, A; Falletti, L; Favuzzi, C; Fegan, S J; Ferrara, E C; Focke, W B; Franckowiak, A; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grégoire, T; Grenier, I A; Grondin, M -H; Grove, J E; Guiriec, S; Hadasch, D; Hanabata, Y; Harding, A K; Hayashida, M; Hayashi, K; Hays, E; Hewitt, J; Hill, A B; Horan, D; Hou, X; Hughes, R E; Inoue, Y; Jackson, M S; Jogler, T; Jóhannesson, G; Johnson, A S; Kamae, T; Kawano, T; Kerr, M; Knödlseder, J; Kuss, M; Lande, J; Larsson, S; Latronico, L; Lemoine-Goumard, M; Longo, F; Loparco, F; Lovellette, M N; Lubrano, P; Marelli, M; Massaro, F; Mayer, M; 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; 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; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Roth, M; Rousseau, R; Parkinson, P M Saz; Schulz, A; Sgrò, C; Siskind, E J; Smith, D A; Spandre, G; Spinelli, P; Suson, D J; Takahashi, H; Takeuchi, Y; Thayer, J G; Thayer, J B; Thompson, D J; Tibaldo, L; Tibolla, O; Tinivella, M; Torres, D F; Tosti, G; Troja, E; Uchiyama, Y; Vandenbroucke, J; Vasileiou, V; Vianello, G; Vitale, V; Werner, M; Winer, B L; Wood, K S; Yang, Z

    2013-01-01

    Pulsar wind nebulae (PWNe) have been established as the most populous class of TeV gamma-ray emitters. Since launch, the Fermi Large Area Telescope (LAT)identified five high-energy (100MeV large number of PWNe candidates, all powered by young and energetic pulsars. The wealth of multi-wavelength data available and the new results provided by Fermi-LAT give us an opportunity to find new PWNe and to explore the radiative processes taking place in known ones. The TeV gamma-ray unidentifiedsources (UNIDs) are the best candidates for finding new PWNe. Using 45 months of Fermi-LAT data for energies above 10 GeV, an analysis was performed near the position of 58TeV PWNe and UNIDs within 5deg of the Galactic Plane to establish new constraints on PWNe properties and find new clues on the nature of UNIDs. Of the 58 sources, 30 were detected, and this work provides their gamma-rayfluxes for energies above 10 GeV. The spectral energy distributions (SED) anduppe...

  12. On the 2012 October 23 Circular Ribbon Flare: Emission Features and Magnetic Topology

    NASA Astrophysics Data System (ADS)

    Yang, Kai; Guo, Yang; Ding, M. D.

    2015-06-01

    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.

  13. Positions of equilibrium points for dust particles in the circular restricted three-body problem with radiation

    NASA Astrophysics Data System (ADS)

    Pástor, P.

    2014-11-01

    For a body with negligible mass moving in the gravitational field of a star with one planet in a circular orbit (the circular restricted three-body problem), five equilibrium points exist and are known as the Lagrangian points. The positions of the Lagrangian points are not valid for dust particles because in the derivation of the Lagrangian points it is assumed that no other forces besides the gravitation act on the body with negligible mass. Here, we determined positions of the equilibrium points for the dust particles in the circular restricted three-body problem with radiation. The equilibrium points are located on curves connecting the Lagrangian points in the circular restricted three-body problem. The equilibrium points for Jupiter are distributed in large interval of heliocentric distances due to its large mass. The equilibrium points for the Earth explain a cloud of dust particles trailing the Earth observed with the Spitzer Space Telescope. The dust particles moving in the equilibrium points are distributed in interplanetary space according to their properties.

  14. Large-scale interplanetary magnetic fields: Voyager 1 and 2 observations between 1 AU and 9.5 AU

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Klein, L. W.; Lepping, R. P.; Behannon, K. W.

    1984-01-01

    The large-scale radial and temporal variations of the interplanetary magnetic field strength B observed by Voyagers 1 and 2 are discussed. Two components of the magnetic field strength were considered: (1) an average component, B sub zero, based on solar rotation averages, and (2) a fluctuation component, delta B, expressed by 10- or 24-hour averages of B normalized by the best-fit average field for the corresponding time and distance. Observations of the sector structure, interfaces, and shocks are presented to further describe magnetic field strength.

  15. Fermi large area telescope observations of the cosmic-ray induced ?-ray emission of the Earth’s atmosphere

    Microsoft Academic Search

    A. A. Abdo; M. Ackermann; M. Ajello; W. B. Atwood; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; B. M. Baughman; K. Bechtol; R. Bellazzini; B. Berenji; E. D. Bloom; E. Bonamente; A. W. Borgland; A. Bouvier; J. Bregeon; A. Brez; M. Brigida; P. Bruel; R. Buehler; T. H. Burnett; S. Buson; G. A. Caliandro; R. A. Cameron; P. A. Caraveo; J. M. Casandjian; C. Cecchi; Ö. Çelik; E. Charles; A. Chekhtman; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; J. Conrad; F. de Palma; S. W. Digel; E. do Couto e Silva; P. S. Drell; R. Dubois; D. Dumora; C. Farnier; C. Favuzzi; S. J. Fegan; W. B. Focke; P. Fortin; M. Frailis; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; N. Giglietto; S. Germani; B. Giebels; F. Giordano; T. Glanzman; G. Godfrey; I. A. Grenier; M.-H. Grondin; J. E. Grove; L. Guillemot; S. Guiriec; E. Hays; D. Horan; R. E. Hughes; G. Jóhannesson; A. S. Johnson; T. J. Johnson; W. N. Johnson; T. Kamae; H. Katagiri; J. Kataoka; N. Kawai; M. Kerr; J. Knödlseder; M. Kuss; J. Lande; L. Latronico; M. Lemoine-Goumard; F. Longo; F. Loparco; B. Lott; M. N. Lovellette; P. Lubrano; A. Makeev; M. N. Mazziotta; J. E. McEnery; C. Meurer; P. F. Michelson; W. Mitthumsiri; T. Mizuno; C. Monte; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Murgia; P. L. Nolan; J. P. Norris; E. Nuss; T. Ohsugi; A. Okumura; N. Omodei; E. Orlando; J. F. Ormes; D. Paneque; J. H. Panetta; D. Parent; V. Pelassa; M. Pepe; M. Pesce-Rollins; F. Piron; T. A. Porter; S. Rainò; R. Rando; M. Razzano; A. Y. Rodriguez; O. Reimer; T. Reposeur; L. S. Rochester; M. Roth; H. F.-W. Sadrozinski; A. Sander; P. M. Saz Parkinson; C. Sgrò; G. H. Share; E. J. Siskind; D. A. Smith; P. D. Smith; G. Spandre; P. Spinelli; M. S. Strickman; D. J. Suson; H. Takahashi; T. Tanaka; J. B. Thayer; J. G. Thayer; D. J. Thompson; L. Tibaldo; D. F. Torres; G. Tosti; A. Tramacere; Y. Uchiyama; T. L. Usher; V. Vasileiou; N. Vilchez; V. Vitale; A. P. Waite; P. Wang; B. L. Winer; K. S. Wood; T. Ylinen; M. Ziegler

    2009-01-01

    We report on measurements of the cosmic-ray induced gamma-ray emission of\\u000aEarth's atmosphere by the Large Area Telescope onboard the Fermi Gamma-ray\\u000aSpace Telescope. The LAT has observed the Earth during its commissioning phase\\u000aand with a dedicated Earth-limb following observation in September 2008. These\\u000ameasurements yielded 6.4 x 10^6 photons with energies >100MeV and ~250hours\\u000atotal livetime for the

  16. Direct observation of surface diffusion of large organic molecules at metal surfaces: PVBA on Pd(110)

    NASA Astrophysics Data System (ADS)

    Weckesser, Jens; Barth, Johannes V.; Kern, Klaus

    1999-03-01

    The bonding and surface diffusion of 4-trans-2-(pyrid-4-yl-vinyl) benzoic acid (PVBA) on Pd(110) was investigated by variable temperature scanning tunneling microscopy at sample temperatures between 300 and 450 K. PVBA is a large organic molecule designed for nonlinear optics applications. At low coverages single PVBA molecules are randomly distributed at the surface where they bind diagonally to three neighboring Pd-rows, leading to four equivalent adsorption configurations. The "dog-bone" molecular structure could be resolved. The molecules' surface diffusion is strictly one-dimensional along the close-packed [11¯0]-direction of the surface Pd atomic rows and obeys an Arrhenius law with an activation barrier of 0.83±0.03 eV and an attempt frequency of 1010.3±0.4 s-1.

  17. Line-of-sight observations at 86 GHz with a very large and a small antenna

    NASA Technical Reports Server (NTRS)

    Vogel, W. J.; Davis, J. H.; Mayer, C. E.

    1984-01-01

    Amplitude variations over a 12.9 km terrestrial line-of-sight path were measured simultaneously on a 1400 lambda and a 29 lambda antenna at 86.16 GHz. Clear atmosphere data from two occasions with considerably different meteorological conditions are presented. Both sets have statistical and spectral parameters in good agreement with turbulence theory. Some of the data taken after a thunderstorm front passage show a slow gain reduction of the large antenna of up to 2 dB and an increase in variance to a level above that of the small antenna. The power spectral density of these data reveals that the excess fluctuation power is in the region of the spectrum which turbulence theory predicts to be flat. It shows an approximate 1/f dependence. It is attributed to refractive bending of up to 0.025 deg. Gain reductions due to turbulence or turbulence induced angle-of-arrival variations were estimated to be negligible.

  18. Observation of Large-Angle Quasimonoenergetic Electrons from a Laser Wakefield

    SciTech Connect

    Kaganovich, D.; Gordon, D. F.; Ting, A. [Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States)

    2008-05-30

    A relativistically intense laser pulse is focused into a helium jet and quasimonoenergetic electrons emitted at a 40 deg. angle with respect to the laser axis are observed. The average electron energy is between 1 and 2 MeV and the total accelerated charge is about 1 nC emitted in a 10 deg. cone angle. Three dimensional particle-in-cell simulations reproduce key features of the experimental results and show that the interaction between ionization heating and nonlinear cavitation wakefields is responsible for the acceleration.

  19. Herschel Observations of a Newly Discovered UX Ori Star in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Clayton, Geoffrey

    2010-10-01

    The LMC star, SSTISAGE1C J050756.44--703453.9, was first noticed during a survey of EROS-2 lightcurves for stars with large irregular brightness variations typical of the R Coronae Borealis (RCB) class. However, the visible spectrum showing emission lines including the Balmer and Paschen series as well as many Fe II lines is emphatically not that of an RCB star. This star has all of the characteristics of a typical UX Ori star. It has a spectral type of approximately A2 and has excited an H II region in its vicinity. However, if it is an LMC member, then it is very luminous for a Herbig Ae/Be star. It shows irregular drops in brightness of up to 2 mag, and displays the reddening and ``blueing'' typical of this class of stars. Its spectrum, showing a combination of emission and absorption lines, is typical of a UX Ori star that is in a decline caused by obscuration from the circumstellar dust. SSTISAGE1C J050756.44--703453.9 has a strong IR excess and significant emission is present out to 500 . Monte Carlo radiative transfer modeling of the SED requires that SSTISAGE1C J050756.44--703453.9 has both a dusty disk as well as a large extended diffuse envelope to fit both the mid- and far-IR dust emission. This star is a new member of the UX Ori subclass of the Herbig Ae/Be stars and only the second such star to be discovered in the LMC.

  20. HERSCHEL OBSERVATIONS OF A NEWLY DISCOVERED UX Ori STAR IN THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Clayton, Geoffrey C. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Sargent, B.; Boyer, M. L.; Meixner, M.; Roman-Duval, J.; Sewilo, M., E-mail: gclayton@fenway.phys.lsu.ed, E-mail: duval@stsci.ed, E-mail: mboyer@stsci.ed, E-mail: meixner@stsci.ed, E-mail: mmsewilo@stsci.ed, E-mail: sargent@stsci.ed [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2010-10-20

    The LMC star, SSTISAGE1C J050756.44-703453.9, was first noticed during a survey of EROS-2 light curves for stars with large irregular brightness variations typical of the R Coronae Borealis (RCB) class. However, the visible spectrum showing emission lines including the Balmer and Paschen series as well as many Fe II lines is emphatically not that of an RCB star. This star has all of the characteristics of a typical UX Ori star. It has a spectral type of approximately A2 and has excited an H II region in its vicinity. However, if it is an LMC member, then it is very luminous for a Herbig Ae/Be star. It shows irregular drops in brightness of up to 2 mag, and displays the reddening and 'blueing' typical of this class of stars. Its spectrum, showing a combination of emission and absorption lines, is typical of a UX Ori star that is in a decline caused by obscuration from the circumstellar dust. SSTISAGE1C J050756.44-703453.9 has a strong IR excess and significant emission is present out to 500 {mu}m. Monte Carlo radiative transfer modeling of the spectral energy distribution requires that SSTISAGE1C J050756.44-703453.9 have both a dusty disk as well as a large extended diffuse envelope to fit both the mid- and far-IR dust emission. This star is a new member of the UX Ori subclass of the Herbig Ae/Be stars and only the second such star to be discovered in the LMC.

  1. Resonance Splitting in RF Cylindrical Cavities with Circular Apertures

    NASA Astrophysics Data System (ADS)

    Martinez, Luis

    2015-03-01

    Coupling of two RF cylindrical cavities is achieved with the use of a single, thin, circular aperture (iris) located between the two cavities in the transverse plane. A tunable splitting, in which the single resonance splits into a closely spaced doublet for the TE011 mode is experimentally observed. It is found that the frequency spacing of the doublet is related to the circular aperture size. A model based on the analogy of a multi-mirror optical Fabry-Perot cavity, in which the frequency spacing of the doublet is related to the reflection coefficient, is found to be in excellent agreement with the experimental results. Calculation of the reflection coefficient for the circular aperture is performed using the closed form solutions derived from scattering amplitude and circular aperture theory.

  2. Angular momentum-induced circular dichroism in non-chiral nanostructures.

    PubMed

    Zambrana-Puyalto, Xavier; Vidal, Xavier; Molina-Terriza, Gabriel

    2014-01-01

    Circular dichroism, that is, the differential absorption of a system to left and right circularly polarized light, is one of the only techniques capable of providing morphological information of certain samples. In biology, for instance, circular dichroism spectroscopy is widely used to study the structure of proteins. More recently, it has also been used to characterize metamaterials and plasmonic structures. Typically, circular dichorism can only be observed in chiral objects. Here we present experimental results showing that a non-chiral sample such as a subwavelength circular nanoaperture can produce giant circular dichroism when a vortex beam is used to excite it. These measurements can be understood by studying the symmetries of the sample and the total angular momentum that vortex beams carry. Our results show that circular dichroism can provide a wealth of information about the sample when combined with the control of the total angular momentum of the input field. PMID:25215603

  3. Fermi large area telescope observations of the cosmic-ray induced ?-ray emission of the Earth's atmosphere

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; de Palma, F.; Digel, S. W.; Do Couto E Silva, E.; Drell, P. S.; Dubois, R.; Dumora, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hays, E.; Horan, D.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Mazziotta, M. N.; McEnery, J. E.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Rochester, L. S.; Rodriguez, A. Y.; Roth, M.; Sadrozinski, H. F.-W.; Sander, A.; Saz Parkinson, P. M.; Sgrò, C.; Share, G. H.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Suson, D. J.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vasileiou, V.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Ylinen, T.; Ziegler, M.

    2009-12-01

    We report on measurements of the cosmic-ray induced ?-ray emission of Earth’s atmosphere by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The Large Area Telescope has observed the Earth during its commissioning phase and with a dedicated Earth limb following observation in September 2008. These measurements yielded ˜6.4×106 photons with energies >100MeV and ˜250 hours total live time 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 ?=2.79±0.06.

  4. Fermi large area telescope observations of the cosmic-ray induced {gamma}-ray emission of the Earth's atmosphere

    SciTech Connect

    Abdo, A. A. [Space Science Division, Naval Research Laboratory, Washington, D.C. 20375 (United States); National Academy of Sciences, Washington, D.C. 20001 (United States); Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Bloom, E. D.; Borgland, A. W.; Bouvier, A.; Buehler, R.; Cameron, R. A.; Charles, E.; Chiang, J.; Claus, R.; Digel, S. W.; Couto e Silva, E. do; Drell, P. S.; Dubois, R.; Focke, W. B.; Funk, S.; Glanzman, T. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, California 94305 (United States)] (and others)

    2009-12-15

    We report on measurements of the cosmic-ray induced {gamma}-ray emission of Earth's atmosphere by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The Large Area Telescope has observed the Earth during its commissioning phase and with a dedicated Earth limb following observation in September 2008. These measurements yielded {approx}6.4x10{sup 6} photons with energies >100 MeV and {approx}250 hours total live time 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 {gamma}=2.79{+-}0.06.

  5. 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.

  6. Fermi-Large Area Telescope Observations of the Exceptional Gamma-ray Outbursts of 3C 273 in 2009 September

    Microsoft Academic Search

    A. A. Abdo; M. Ackermann; M. Ajello; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; K. Bechtol; R. Bellazzini; B. Berenji; R. D. Blandford; E. D. Bloom; E. Bonamente; A. W. Borgland; A. Bouvier; J. Bregeon; A. Brez; M. Brigida; P. Bruel; T. H. Burnett; S. Buson; G. A. Caliandro; R. A. Cameron; A. Cannon; P. A. Caraveo; S. Carrigan; J. M. Casandjian; E. Cavazzuti; C. Cecchi; Ö. Çelik; E. Charles; A. Chekhtman; C. C. Cheung; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; J. Conrad; L. Costamante; C. D. Dermer; A. de Angelis; F. de Palma; E. do Couto e. Silva; P. S. Drell; R. Dubois; D. Dumora; C. Farnier; C. Favuzzi; S. J. Fegan; W. B. Focke; M. Frailis; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Gehrels; S. Germani; N. Giglietto; P. Giommi; F. Giordano; T. Glanzman; G. Godfrey; I. A. Grenier; M.-H. Grondin; S. Guiriec; M. Hayashida; E. Hays; A. B. Hill; D. Horan; R. E. Hughes; G. Jóhannesson; A. S. Johnson; W. N. Johnson; T. Kamae; H. Katagiri; J. Kataoka; N. Kawai; J. Knödlseder; M. Kuss; J. Lande; S. Larsson; L. Latronico; M. Lemoine-Goumard; M. Llena Garde; F. Longo; F. Loparco; B. Lott; M. N. Lovellette; P. Lubrano; G. M. Madejski; A. Makeev; O. Mansutti; E. Massaro; M. N. Mazziotta; W. McConville; J. E. McEnery; C. Meurer; P. F. Michelson; W. Mitthumsiri; T. Mizuno; A. A. Moiseev; C. Monte; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Murgia; P. L. Nolan; J. P. Norris; E. Nuss; T. Ohsugi; N. Omodei; E. Orlando; J. F. Ormes; D. Paneque; J. H. Panetta; V. Pelassa; M. Pepe; M. Pesce-Rollins; F. Piron; T. A. Porter; S. Rainò; R. Rando; M. Razzano; A. Reimer; O. Reimer; S. Ritz; A. Y. Rodriguez; R. W. Romani; M. Roth; F. Ryde; H. F.-W. Sadrozinski; A. Sander; J. D. Scargle; T. L. Schalk; C. Sgrò; E. J. Siskind; P. D. Smith; G. Spandre; P. Spinelli; J.-L. Starck; M. S. Strickman; D. J. Suson; H. Tajima; H. Takahashi; T. Takahashi; T. Tanaka; J. B. Thayer; J. G. Thayer; D. J. Thompson; L. Tibaldo; D. F. Torres; G. Tosti; A. Tramacere; Y. Uchiyama; T. L. Usher; V. Vasileiou; N. Vilchez; V. Vitale; A. P. Waite; P. Wang; A. E. Wehrle; B. L. Winer; K. S. Wood; Z. Yang; T. Ylinen; M. Ziegler

    2010-01-01

    We present the light curves and spectral data of two exceptionally luminous gamma-ray outbursts observed by the Large Area Telescope experiment on board the Fermi Gamma-ray Space Telescope from 3C 273 in 2009 September. During these flares, having a duration of a few days, the source reached its highest gamma-ray flux ever measured. This allowed us to study, in some

  7. The Brightness of Density Structures at Large Solar Elongation Angles: What Is Being Observed by STEREO SECCHI?

    Microsoft Academic Search

    N. Lugaz; A. Vourlidas; I. I. Roussev; C. Jacobs; W. B. Manchester IV; O. Cohen

    2008-01-01

    We discuss features of coronal mass ejections (CMEs) that are specific to heliospheric observations at large elongation angles. Our analysis is focused on a series of two eruptions that occurred on 2007 January 24-25, which were tracked by the Heliospheric Imagers (HIs) on board STEREO. Using a three-dimensional (3D) magnetohydrodynamic simulation of these ejections with the Space Weather Modeling Framework

  8. Observation of large positive and negative lateral shifts of a reflected beam from symmetrical metal-cladding waveguides.

    PubMed

    Chen, Lin; Cao, Zhuangqi; Ou, Fang; Li, Honggen; Shen, Qishun; Qiao, Huicong

    2007-06-01

    Both large positive and negative lateral shifts were observed for the reflected light beam on a symmetrical metal-cladding waveguide. The positive and negative shifts approach about 480 and 180 microm, respectively, which to our knowledge are the largest experimental results ever reported. The experiment also proves that the positive or the negative shift depends on sign of the difference between the intrinsic and radiative damping. PMID:17546145

  9. Circular High-Impedance Surfaces Characterization

    Microsoft Academic Search

    Julien Sarrazin; Anne-Claire Lepage; Xavier Begaud

    2012-01-01

    In this letter, characterization of circular high-impedance surfaces (HISs) is investigated. The reflection phase characterization used for rectangular HISs is here extended to circular lattices. Circular HISs discussed in this letter present a 2-D periodicity, and consequently the phase diagram is determined for concentric and radial polarizations. The effect of mapping a rectangular HIS into a circular one is investigated

  10. 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, the peak will first develop a central depression, due to the flow of low-strength melted materials, when the melt volume begins to intersect the transient-cavity base.

  11. Occasional large emissions of nitrous oxide and methane observed in stormwater biofiltration systems.

    PubMed

    Grover, Samantha P P; Cohan, Amanda; Chan, Hon Sen; Livesley, Stephen J; Beringer, Jason; Daly, Edoardo

    2013-11-01

    Designed, green infrastructures are becoming a customary feature of the urban landscape. Sustainable technologies for stormwater management, and biofilters in particular, are increasingly used to reduce stormwater runoff volumes and peaks as well as improve the water quality of runoff discharged into urban water bodies. Although a lot of research has been devoted to these technologies, their effect in terms of greenhouse gas fluxes in urban areas has not been yet investigated. We present the first study aimed at quantifying greenhouse gas fluxes between the soil of stormwater biofilters and the atmosphere. N2O, CH4, and CO2 were measured periodically over a year in two operational vegetated biofiltration cells at Monash University in Melbourne, Australia. One cell had a saturated zone at the bottom, and compost and hardwood mulch added to the sandy loam filter media. The other cell had no saturated zone and was composed of sandy loam. Similar sedges were planted in both cells. The biofilter soil was a small N2O source and a sink for CH4 for most measurement events, with occasional large emissions of both N2O and CH4 under very wet conditions. Average N2O fluxes from the cell with the saturated zone were almost five-fold greater (65.6 ?g N2O-N m(-2) h(-1)) than from the other cell (13.7 ?g N2O-N m(-2) h(-1)), with peaks up to 1100 ?g N2O-N m(-2) h(-1). These N2O fluxes are of similar magnitude to those measured in other urban soils, but with larger peak emissions. The CH4 sink strength of the cell with the saturated zone (-3.8 ?g CH4-C m(-2) h(-1)) was lower than the other cell (-18.3 ?g CH4-C m(-2) h(-1)). Both cells of the biofilter appeared to take up CH4 at similar rates to other urban lawn systems; however, the biofilter cells displayed occasional large CH4 emissions following inflow events, which were not seen in other urban systems. CO2 fluxes increased with soil temperature in both cells, and in the cell without the saturated zone CO2 fluxes decreased as soil moisture increased. Other studies of CO2 fluxes from urban soils have found both similar and larger CO2 emissions than those measured in the biofilter. The results of this study suggest that the greenhouse gas footprint of stormwater treatment warrant consideration in the planning and implementation of engineered green infrastructures. PMID:23399408

  12. 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.

  13. Fermi Large Area Telescope Observations of the Cygnus Loop Supernova Remnant

    SciTech Connect

    Katagiri, H.; /Ibaraki U., Mito; Tibaldo, L.; /INFN, Padua /Padua U. /Paris U., VI-VII; Ballet, J.; /Paris U., VI-VII; Giordano, F.; /Bari U. /Bari Polytechnic /INFN, Bari; Grenier, I.A.; /Paris U., VI-VII; Porter, T.A.; /Stanford U., HEPL /KIPAC, Menlo Park /SLAC; Roth, M.; /Washington U., Seattle; Tibolla, O.; /Wurzburg U.; Uchiyama, Y.; /Stanford U., HEPL /KIPAC, Menlo Park /SLAC; 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.

  14. Observational Study of Large Amplitude Longitudinal Oscillations in a Solar Filament

    NASA Astrophysics Data System (ADS)

    Knizhnik, Kalman; Luna, Manuel; Muglach, Karin; Gilbert, Holly; Kucera, Therese; Karpen, Judith

    2014-01-01

    On 20 August 2010 an energetic disturbance triggered damped large-amplitude longitudinal (LAL) oscillations in almost an entire filament. In the present work we analyze this periodic motion in the filament to characterize the damping and restoring mechanism of the oscillation. Our method involves placing slits along the axis of the filament at different angles with respect to the spine of the filament, finding the angle at which the oscillation is clearest, and fitting the resulting oscillation pattern to decaying sinusoidal and Bessel functions. These functions represent the equations of motion of a pendulum damped by mass accretion. With this method we determine the period and the decaying time of the oscillation. Our preliminary results support the theory presented by Luna and Karpen (2012) that the restoring force of LAL oscillations is solar gravity in the tubes where the threads oscillate, and the damping mechanism is the ongoing accumulation of mass onto the oscillating threads. Following an earlier paper, we have determined the magnitude and radius of curvature of the dipped magnetic flux tubes hosting a thread along the filament, as well as the mass accretion rate of the filament threads, via the fitted parameters.

  15. Large-Scale Structures Behind the Southern Milky Way from Observations of Partially Obscured Galaxies

    E-print Network

    R. C. Kraan-Korteweg; P. A. Woudt; P. A. Henning

    1996-11-13

    We report here on extragalactic large-scale structures uncovered by a deep optical survey for galaxies behind the southern Milky Way. Systematic visual inspection of the ESO/SRC-survey revealed over 10000 previously unknown galaxies in the region 265 Milky Way are unveiled, such as a filament at ~ 2500 km/s connecting to the Hydra and Antlia clusters, a shallow extended supercluster in Vela (~ 6000km/s), and a nearby (4882 km/s), very massive (M ~ 2-5 10^15 Msun), rich Coma-like cluster which seems to constitute the previously unidentified center of the Great Attractor. The innermost part of the Milky Way where the foreground obscuration in the blue is 5mag, respectively HI-column densities greater than 6 10^21 / cm^2 remains fully opaque. In this approximately 8 degrees wide strip, the forthcoming blind HI-survey with the multi-beam system at Parkes will provide the only tool to unveil this part of the extragalactic sky.

  16. 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.

  17. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE SUPERNOVA REMNANT W28 (G6.4-0.1)

    SciTech Connect

    Abdo, A. A. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Ackermann, M.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bouvier, A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Baldini, L.; Bellazzini, R.; Bregeon, J. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d'Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bonamente, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Brandt, T. J. [Centre d'Etude Spatiale des Rayonnements, CNRS/UPS, BP 44346, F-30128 Toulouse Cedex 4 (France); Brigida, M. [Dipartimento di Fisica 'M. Merlin' dell'Universita e del Politecnico di Bari, I-70126 Bari (Italy); Bruel, P., E-mail: htajima@slac.stanford.ed, E-mail: ttanaka@slac.stanford.ed, E-mail: uchiyama@slac.stanford.ed, E-mail: katagiri@hep01.hepl.hiroshima-u.ac.j [Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Palaiseau (France)

    2010-07-20

    We present detailed analysis of two gamma-ray sources, 1FGL J1801.3-2322c and 1FGL J1800.5-2359c, that have been found toward the supernova remnant (SNR) W28 with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. 1FGL J1801.3-2322c is found to be an extended source within the boundary of SNR W28, and to extensively overlap with the TeV gamma-ray source HESS J1801-233, which is associated with a dense molecular cloud interacting with the SNR. The gamma-ray spectrum measured with the LAT from 0.2 to 100 GeV can be described by a broken power-law function with a break at {approx}1 GeV and photon indices of 2.09 {+-} 0.08 (stat) {+-} 0.28 (sys) below the break and 2.74 {+-} 0.06 (stat) {+-} 0.09 (sys) above the break. Given the clear association between HESS J1801-233 and the shocked molecular cloud and a smoothly connected spectrum in the GeV-TeV band, we consider the origin of the gamma-ray emission in both GeV and TeV ranges to be the interaction between particles accelerated in the SNR and the molecular cloud. The decay of neutral pions produced in interactions between accelerated hadrons and dense molecular gas provides a reasonable explanation for the broadband gamma-ray spectrum. 1FGL J1800.5-2359c, located outside the southern boundary of SNR W28, cannot be resolved. An upper limit on the size of the gamma-ray emission was estimated to be {approx}16' using events above {approx}2 GeV under the assumption of a circular shape with uniform surface brightness. It appears to coincide with the TeV source HESS J1800-240B, which is considered to be associated with a dense molecular cloud that contains the ultra compact H II region W28A2 (G5.89-0.39). We found no significant gamma-ray emission in the LAT energy band at the positions of TeV sources HESS J1800-230A and HESS J1800-230C. The LAT data for HESS J1800-230A combined with the TeV data points indicate a spectral break between 10 GeV and 100 GeV.

  18. 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, ?.; 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; Aleksi?, 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.; Terzi?, 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.

    2011-08-01

    We report on the ?-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) ?-ray spectrum above 0.3 GeV can be well described by a power-law function with photon index ? = 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 ?-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.

  19. Circular Harmonic Decomposition Approach for Numerical Inversion of Circular Radon Transforms

    E-print Network

    Paris-Sud XI, Université de

    Circular Harmonic Decomposition Approach for Numerical Inversion of Circular Radon Transforms Gaël@num.uni-sb.de ABSTRACT Numerical inversions via circular harmonic decomposition for two classes of circular Radon transforms are established. The first class deals with the Radon transform (RT) de- fined on circular arcs

  20. Unexpected large uptake of O3 on sea salts and the observed Br2 formation

    NASA Astrophysics Data System (ADS)

    Mochida, Michihiro; Hirokawa, Jun; Akimoto, Hajime

    2000-09-01

    Uptake coefficients of O3 on various model compounds of sea salts at ambient temperature were measured using a Knudsen cell reactor coupled to a differentially pumped quadrupole mass spectrometer. Uptake of O3 was below the detection limit (<1×10-5) for pure alkali metal bromides, whereas reactive uptake with Br2 formation was observed on two types of synthetic sea salts (Aqua Ocean and Instant Ocean) and commercial natural sea salt. Measured uptake coefficients were 10-2-10-3, (1.4±1.1) × 10-3 and (9.7±4.6) × 10-4 for Aqua Ocean, Instant Ocean and natural sea salt, respectively. These uptake coefficients were about three orders of magnitude larger than that on bulk bromide solution estimated from known liquid phase reactions. The results imply that minor components enhance reactivity of O3 on synthetic and natural sea salts. This heterogeneous reaction is potentially an important Br source in the marine boundary layer on a global scale as well as in the polar troposphere.

  1. Observation of the Mold-Filling Process of a Large Hydro-Turbine Guide Vane Casting

    NASA Astrophysics Data System (ADS)

    Kang, Jinwu; Long, Haimin; Li, Yongjie; You, Rui; Hao, Xiaokun; Nie, Gang; Wang, Tianjiao; Zhang, Chengchun

    2015-02-01

    The mold-filling process has a determining effect on the quality of castings, and it has always been a hot but difficult research topic. The authors developed a wireless monitoring system for the mold-filling process of castings based on a contact time method and an observation system based on heat-resistant high-speed cameras. By using these two systems, the filling process of a turbine guide vane casting with a stepped gating system was investigated. The filling profile of the casting was recorded, and the filling time of nine typical positions was acquired. These results show that at the beginning, the liquid steel flowed out from the top ingate, which was designed to be the last to fill. The numerical simulation of the filling of the guide vane was performed, and the outflow from the top ingate were predicted. Finally, the gating system of the casting was improved with enlarged sprue. The new design features bigger sprue to ingate ratio; therefore, it could avoid the overflow from the top ingate and realize stable filling.

  2. Large-Area Balloon-Borne Polarized Gamma Ray Observer (PoGO)

    SciTech Connect

    Andersson, V.; Chen, P.; Kamae, T.; Madejski, G.; Mizuno, T.; Ng, J.; Tajima, H.; Thurston, T.; /SLAC; Bogaert, G.; /Ecole Polytechnique; Fukazawa, Y.; /Hiroshima U.; Saito,; Takahashi, T.; /Sagamihara, Inst. Space Astron. Sci.; Barbier, L.; Bloser, P.; Harding, A.; Hunter, S.; Krizmanic, J.; Mitchell, J.; Streitmatter, R.; Fernholz, R.; Groth, E.; /NASA, Goddard /Princeton U. /Royal Inst. Tech., Kista /Stockholm U. /Tokyo Inst. Tech. /Yamagata U.

    2005-06-30

    We are developing a new balloon-borne instrument (PoGO), to measure polarization of soft gamma rays (30-200 keV) using asymmetry in azimuth angle distribution of Compton scattering. PoGO is designed to detect 10% polarization in 100mCrab sources in a 6-8 hour observation and bring a new dimension to studies on gamma ray emission/transportation mechanism in pulsars, AGNs, black hole binaries, and neutron star surface. The concept is an adaptation to polarization measurements of well-type phoswich counter consisting of a fast plastic scintillator (the detection part), a slow plastic scintillator (the active collimator) and a BGO scintillator (the bottom anti-counter). PoGO consists of close-packed array of 217 hexagonal well-type phoswich counters and has a narrow field-of-view ({approx} 5 deg{sup 2}) to reduce possible source confusion. A prototype instrument has been tested in the polarized soft gamma-ray beams at Advanced Photon Source (ANL) and at Photon Factory (KEK). On the results, the polarization dependence of EGS4 has been validated and that of Geant4 has been corrected.

  3. Constraints on Lorentz Invariance Violating Quantum Gravity and Large Extra Dimensions Models using High Energy Gamma Ray Observations

    E-print Network

    F. W. Stecker

    2003-08-21

    Observations of the multi-TeV spectra of the nearby BL objects Mkn 421 and Mkn 501 exhibit the high energy cutoffs predicted to be the result of intergalactic annihilation interactions, primarily with infrared photons having a flux level as determined by various astronomical observations. After correction for this absorption effect, the derived intrinsic spectra of these multi-TeV sources can be explained within the framework of simple synchrotron self-Compton emission models. Stecker and Glashow have shown that the existence of such annihilations via electron-positron pair production interactions up to an energy of 20 TeV puts strong constraints on Lorentz invariance violation. Such constraints have important implications for Lorentz invariance violating (LIV) quantum gravity models as well as LIV models involving large extra dimensions. We also discuss the implications of observations of high energy gamma-rays from the Crab Nebula on constraining quantum gravity models.

  4. Fermi Large Area Telescope Observations of the Supernova Remnant G8.7-0.1

    NASA Astrophysics Data System (ADS)

    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.; Casandjian, J. M.; Cecchi, C.; Charles, E.; Chekhtman, A.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cutini, S.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Frailis, M.; Fukazawa, Y.; Fukui, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashi, K.; Hays, E.; Itoh, R.; Jóhannesson, G.; Johnson, A. S.; Kamae, T.; Katagiri, H.; Kataoka, J.; Knödlseder, J.; Kubo, H.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Lionetto, A. M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Mazziotta, M. N.; Mehault, J.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; 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.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Parent, D.; Pelassa, V.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Reimer, A.; Reimer, O.; Reposeur, T.; Roth, M.; Sadrozinski, H. F.-W.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Tibaldo, L.; Tibolla, O.; Torres, D. F.; Tosti, G.; Tramacere, A.; Troja, E.; Uchiyama, Y.; Uehara, T.; Usher, T. L.; Vandenbroucke, J.; Van Etten, A.; Vasileiou, V.; Vianello, G.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yamamoto, H.; Yamazaki, R.; Yang, Z.; Yasuda, H.; Ziegler, M.; Zimmer, S.

    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) 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 ?0s 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 G8.7-0.1

    SciTech Connect

    Ajello, M.; Allafort, A.; /Stanford U., HEPL /KIPAC, Menlo Park /SLAC; Baldini, L.; /INFN, Pisa; Ballet, J.; /AIM, Saclay; Barbiellini, G.; /INFN, Trieste /Trieste U.; Bastieri, D.; /INFN, Padua /Padua U.; Bechtol, K.; /Stanford U., HEPL /KIPAC, Menlo Park /SLAC; Bellazzini, R.; /INFN, Pisa; Berenji, B.; Blandford, R.D.; Bloom, E.D.; /Stanford U., HEPL /KIPAC, Menlo Park /SLAC; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /Stanford U., HEPL /KIPAC, Menlo Park /SLAC; Bregeon, J.; /INFN, Pisa; Brigida, M.; /Bari Polytechnic /INFN, Bari; Bruel, P.; /Ecole Polytechnique; Buehler, R.; /Stanford U., HEPL /KIPAC, Menlo Park /SLAC; Buson, S.; /INFN, Padua /Padua U.; Caliandro, G.A.; /CSIC, Catalunya; Cameron, R.A.; /Stanford U., HEPL /KIPAC, Menlo Park /SLAC; Caraveo, P.A.; /IASF, Milan /AIM, Saclay /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /Unlisted, US /Naval Research Lab, Wash., D.C. /Perugia U. /ASDC, Frascati /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /Montpellier U. /ASDC, Frascati /Udine U. /INFN, Trieste /Bari Polytechnic /INFN, Bari /Naval Research Lab, Wash., D.C. /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /Bari Polytechnic /INFN, Bari /Ecole Polytechnique /NASA, Goddard /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /Udine U. /INFN, Trieste /Trieste Observ. /Hiroshima U. /Nagoya U. /Bari Polytechnic /INFN, Bari /INFN, Bari /ASDC, Frascati /INFN, Perugia /Perugia U. /Bari Polytechnic /INFN, Bari /ASDC, Frascati /Bari Polytechnic /INFN, Bari /Bologna Observ. /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /Naval Research Lab, Wash., D.C. /Alabama U., Huntsville /CSIC, Catalunya /Hiroshima U. /NASA, Goddard /Hiroshima U.; /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.

  6. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF MARKARIAN 421: THE MISSING PIECE OF ITS SPECTRAL ENERGY DISTRIBUTION

    SciTech Connect

    Abdo, A. A. [National Research Council Research Associate, National Academy of Sciences, Washington, DC 20001 (United States); Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Buehler, R. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d'Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bonamente, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Bouvier, A. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Brigida, M. [Dipartimento di Fisica 'M. Merlin' dell'Universita e del Politecnico di Bari, I-70126 Bari (Italy); Bruel, P., E-mail: dpaneque@mppmu.mpg.de, E-mail: anita.reimer@uibk.ac.at, E-mail: georgano@umbc.edu, E-mail: justin.finke@nrl.navy.mil, E-mail: diegot@ifae.es [Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Palaiseau (France)

    2011-08-01

    We report on the {gamma}-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) {gamma}-ray spectrum above 0.3 GeV can be well described by a power-law function with photon index {Gamma} = 1.78 {+-} 0.02 and average photon flux F(> 0.3 GeV) = (7.23 {+-} 0.16) x 10{sup -8} ph cm{sup -2} s{sup -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 {approx}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 {gamma}-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.

  7. Large-Area Balloon-Borne Polarized Gamma Ray Observer (PoGO)

    SciTech Connect

    Blanford, R.

    2005-04-06

    We are developing a new balloon-borne instrument (PoGO), to measure polarization of soft gamma rays (25-200 keV) using asymmetry in azimuth angle distribution of Compton scattering. PoGO will detect 10% polarization in 100mCrab sources in a 6-8 hour observation and bring a new dimension to studies on gamma ray emission/transportation mechanism in pulsars, AGNs, black hole binaries, and neutron star surface. The concept is an adaptation to polarization measurements of well-type phoswich counter technology used in balloon-borne experiments (Welcome-1) and AstroE2 Hard X-ray Detector. PoGO consists of close-packed array of 397 hexagonal well-type phoswich counters. Each unit is composed of a long thin tube (well) of slow plastic scintillator, a solid rod of fast plastic scintillator, and a short BGO at the base. A photomultiplier coupled to the end of the BGO detects light from all 3 scintillators. The rods with decay times < 10 ns, are used as the active elements; while the wells and BGOs, with decay times {approx}250 ns are used as active anti-coincidence. The fast and slow signals are separated out electronically. When gamma rays entering the field-of-view (fwhm {approx} 3deg{sup 2}) strike a fast scintillator, some are Compton scattered. A fraction of the scattered photons are absorbed in another rod (or undergo a second scatter). A valid event requires one clean fast signal of pulse-height compatible with photo-absorption (> 20keV) and one or more compatible with Compton scattering (< 10keV). Studies based on EGS4 (with polarization features) and Geant4 predict excellent background rejection and high sensitivity.

  8. Observations of hysteresis in the annual exchange circulation of a large microtidal estuary

    NASA Astrophysics Data System (ADS)

    Meyers, Steven D.; Wilson, Monica; Luther, Mark. E.

    2015-04-01

    A nonlinear relation between the salinity field and the subtidal exchange circulation in the Tampa Bay estuary is demonstrated using observational data from 1999 to 2011. The data are averaged to form mean monthly climatological values of total freshwater discharge (Q), axial and vertical salinity gradients, and subtidal vertical shear. Well-known steady state solutions indicate that the exchange circulation is linearly proportional to the horizontal salinity gradient, assuming a constant vertical eddy viscosity (Aeff). The exchange flow is found to be multivalued with respect to the horizontal salinity gradient, forming a hysteresis loop in parameter space that passes through three dynamical regimes. Regime I is relatively dry with weak salinity gradients and exchange circulation. Regime II is the wet season (June-September) in which all quantities rapidly increase. In regime III, the exchange flow persists even though Q and the axial salinity gradient are again low. Gradient Richardson numbers and Simpson numbers also form a loop in parameter space with Ri remaining subcritical (turbulent) until the wet season when Ri rises above criticality (weak vertical mixing) where it remains through the end of regime III. The Simpson number is in a narrow range around 0.2, indicating that the horizontal salinity gradient is always a driver of the exchange circulation. The Aeff, estimated from a parameterization of the Richardson number, decreases by almost an order of magnitude from regimes I to II. It remains low during III, indicating that the persistent stratification is insulating the exchange flow from destruction by tidal mixing during this time period.

  9. Nonlinear dissipation of circularly polarized Alfven waves due to the beam-induced obliquely propagating waves

    SciTech Connect

    Nariyuki, Y. [Faculty of Human Development, University of Toyama, 3190, Toyama City, Toyama 930-8555 (Japan); Hada, T. [Department of Earth System Science and Technology, Kyushu University, 6-1, Kasuga City, Fukuoka 816-8580 (Japan); Tsubouchi, K. [Department of Earth and Planetary Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan)

    2012-08-15

    In the present study, the dissipation processes of circularly polarized Alfven waves in solar wind plasmas including beam components are numerically discussed by using a 2-D hybrid simulation code. Numerical results suggest that the parent Alfven waves are rapidly dissipated due to the presence of the beam-induced obliquely propagating waves, such as kinetic Alfven waves. The nonlinear wave-wave coupling is directly evaluated by using the induction equation for the parent wave. It is also observed both in the 1-D and 2-D simulations that the presence of large amplitude Alfven waves strongly suppresses the beam instabilities.

  10. SWAP Observations of the Long-term, Large-scale Evolution of the Extreme-ultraviolet Solar Corona

    NASA Astrophysics Data System (ADS)

    Seaton, Daniel B.; De Groof, Anik; Shearer, Paul; Berghmans, David; Nicula, Bogdan

    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.

  11. Fluctuations in the ionosphere related to Honshu Twin Large Earthquakes of September 2004 observed by the DEMETER and CHAMP satellites

    NASA Astrophysics Data System (ADS)

    Ryu, Kwangsun; Chae, Jang-Soo; Lee, Ensang; Parrot, Michel

    2014-12-01

    While investigating possible precursory signatures of large earthquakes in the ionospheric data measured by the DEMETER and CHAMP satellites, we found ionospheric disturbances related to large earthquakes (M=7.2 and 7.4) that occurred on September 2004 near the south coast of Honshu, Japan. The satellite data were statistically compared with an empirical model and local averages of the large set of data in the study period. A fluctuation in the electron density above the epicenter was observed roughly 2 weeks before the main earthquakes. Surveys of the space weather and geomagnetic activities suggest that these fluctuations were not caused by changes in space conditions or by a geomagnetic storm. The features were also distinct from well-known natural ionospheric anomalies. In addition, a peak-like profile in the ion temperature and lowered O+ density around the region of the epicenter was observed a week before the main earthquakes along the satellite passes whose longitudes are close to the epicenter. The features are more apparent when they are compared with the data more distant from the epicenter, suggesting that the disturbances occur along the geomagnetic field lines. The concurrent measurements of the ion drift velocity suggest the fluctuations were triggered by the vertical plasma drift. The observed anomalies disappeared ? 2 weeks after the quakes. According to the current theories on the seismo-ionospheric coupling, the horizontal electric field at the lower boundary of the ionosphere should have been strengthened by the seismic activity in order for the ionospheric plasma movements above the epicenter and its geomagnetic conjugate regions to trigger the observed ionospheric anomalies.

  12. Characterization and remote sensing of biological particles using circular polarization

    NASA Astrophysics Data System (ADS)

    Nagdimunov, Lev; Kolokolova, Ludmilla; Mackowski, Daniel

    2013-12-01

    Biological molecules are characterized by an intrinsic asymmetry known as homochirality. The result is optical activity of biological materials and circular polarization in the light scattered by microorganisms, cells of living organisms, as well as molecules (e.g. amino acids) of biological origin. Lab measurements (Sparks et al. (2009) [6,7]) have found that light scattered by certain biological systems, in particular photosynthetic organisms, is not only circular polarized but contains a characteristic spectral trend, showing a fast change and reversal of sign for circular polarization within absorption bands. Similar behavior can be expected for other biological and prebiological organics, especially amino acids. We begin our study by reproducing the laboratory measurements for photosynthetic organisms through modeling the biological material as aggregated structures and using the Multiple Sphere T-matrix (MSTM) code for light scattering calculations. We further study how the spectral effect described above depends on the porosity of the aggregates and the size and number of the constituent particles (monomers). We show that larger aggregates are characterized by larger values of circular polarization and discuss how light-scattering characteristics of individual monomers and electromagnetic interaction between them affect this result. We find that circular polarization typically peaks at medium (40-140°) scattering angles, and discuss recommendations for efficient remote observation of circular polarization from (pre)biological systems.

  13. Early sensitivity to arguments: how preschoolers weight circular arguments.

    PubMed

    Mercier, Hugo; Bernard, Stéphane; Clément, Fabrice

    2014-09-01

    Observational studies suggest that children as young as 2 years can evaluate some of the arguments people offer them. However, experimental studies of sensitivity to different arguments have not yet targeted children younger than 5 years. The current study aimed at bridging this gap by testing the ability of preschoolers (3-, 4-, and 5-year-olds) to weight arguments. To do so, it focused on a common type of fallacy-circularity-to which 5-year-olds are sensitive. The current experiment asked children-and, as a group control, adults-to choose between the contradictory opinions of two speakers. In the first task, participants of all age groups favored an opinion supported by a strong argument over an opinion supported by a circular argument. In the second task, 4- and 5-year-olds, but not 3-year-olds or adults, favored the opinion supported by a circular argument over an unsupported opinion. We suggest that the results of these tasks in 3- to 5-year-olds are best interpreted as resulting from the combination of two mechanisms: (a) basic skills of argument evaluations that process the content of arguments, allowing children as young as 3 years to favor non-circular arguments over circular arguments, and (b) a heuristic that leads older children (4- and 5-year-olds) to give some weight to circular arguments, possibly by interpreting these arguments as a cue to speaker dominance. PMID:24485755

  14. 325 MHz VERY LARGE ARRAY OBSERVATIONS OF ULTRACOOL DWARFS TVLM 513-46546 AND 2MASS J0036+1821104

    SciTech Connect

    Jaeger, T. R.; Kassim, N. [US Naval Research Laboratory, Washington, DC 20375 (United States); Osten, R. A. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Lazio, T. J. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Mutel, R. L., E-mail: ted.jaeger.ctr@nrl.navy.mil [Department of Astronomy, University of Iowa, Iowa City, IA 52242 (United States)

    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.

  15. 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

  16. SIMULTANEOUS OBSERVATIONS OF A LARGE-SCALE WAVE EVENT IN THE SOLAR ATMOSPHERE: FROM PHOTOSPHERE TO CORONA

    SciTech Connect

    Shen, Yuandeng; Liu, Yu, E-mail: ydshen@ynao.ac.cn [Yunnan Astronomical Observatory, Chinese Academy of Sciences, Kunming 650011 (China)

    2012-06-20

    For the first time, we report a large-scale wave that was observed simultaneously in the photosphere, chromosphere, transition region, and low corona layers of the solar atmosphere. Using the high temporal and high spatial resolution observations taken by the Solar Magnetic Activity Research Telescope at Hida Observatory and the Atmospheric Imaging Assembly (AIA) on board Solar Dynamic Observatory, we find that the wave evolved synchronously at different heights of the solar atmosphere, and it propagated at a speed of 605 km s{sup -1} and showed a significant deceleration (-424 m s{sup -2}) in the extreme-ultraviolet (EUV) observations. During the initial stage, the wave speed in the EUV observations was 1000 km s{sup -1}, similar to those measured from the AIA 1700 A (967 km s{sup -1}) and 1600 A (893 km s{sup -1}) observations. The wave was reflected by a remote region with open fields, and a slower wave-like feature at a speed of 220 km s{sup -1} was also identified following the primary fast wave. In addition, a type-II radio burst was observed to be associated with the wave. We conclude that this wave should be a fast magnetosonic shock wave, which was first driven by the associated coronal mass ejection and then propagated freely in the corona. As the shock wave propagated, its legs swept the solar surface and thereby resulted in the wave signatures observed in the lower layers of the solar atmosphere. The slower wave-like structure following the primary wave was probably caused by the reconfiguration of the low coronal magnetic fields, as predicted in the field-line stretching model.

  17. Flat plate boundary layer transition induced by a controlled near-wall circular cylinder wake

    NASA Astrophysics Data System (ADS)

    He, Guo-Sheng; Wang, Jin-Jun

    2015-02-01

    The flat plate boundary layer transition induced by the wake of a circular cylinder close to the wall is experimentally investigated using particle image velocimetry (PIV) and hydrogen bubble visualization techniques. The wake of the circular cylinder is controlled by a slot synthetic jet at the rear stagnation point of the circular cylinder. It is found that when the synthetic jet is actuated, the wake can be greatly modified. When the excitation frequency of the synthetic jet is set at the natural shedding frequency of the cylinder wake, the symmetrical shedding pattern can be observed. While the excitation frequency increases to be twice of the natural shedding frequency, the wake appears to be antisymmetrical again, but with the shedding frequency locked onto half of the excitation frequency. Flow visualizations show that spanwise secondary vortices can be induced in the near wall region by these large scale vortices in the wake. It is found that the secondary vortices destabilize into streamwise stretched ? vortices as they convect downstream. After the introduction of the synthetic jet, the destabilization process is promoted. By investigating the disturbance growth inside the boundary layer, it reveals that the synthetic jet can cause earlier initialization of the disturbance growth, thus promoting the transition process of the boundary layer. An explanation is provided that the low frequency components of the wake disturbances, which interact with the boundary layer, are enhanced by the introduction of the synthetic jet. Therefore, the destabilization of the secondary vortices is promoted, and disturbance growth in the boundary layer initiates earlier.

  18. Fermi-Large Area Telescope Observations of the Exceptional Gamma-ray Outbursts of 3C 273 in 2009 September

    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.; Burnett, T. H.; 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.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Costamante, L.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Guiriec, S.; Hayashida, M.; Hays, E.; Hill, A. B.; Horan, D.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Mansutti, O.; Massaro, E.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Ritz, S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Ryde, F.; Sadrozinski, H. F.-W.; Sander, A.; Scargle, J. D.; Schalk, T. L.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J.-L.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vasileiou, V.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Wehrle, A. E.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ylinen, T.; Ziegler, M.

    2010-05-01

    We present the light curves and spectral data of two exceptionally luminous gamma-ray outbursts observed by the Large Area Telescope experiment on board the Fermi Gamma-ray Space Telescope from 3C 273 in 2009 September. During these flares, having a duration of a few days, the source reached its highest ?-ray flux ever measured. This allowed us to study, in some details, their spectral and temporal structures. The rise and the decay are asymmetric on timescales of 6 hr, and the spectral index was significantly harder during the flares than during the preceding 11 months. We also found that short, very intense flares put out the same time-integrated energy as long, less intense flares like that observed in 2009 August.

  19. Observations of Large Scale Sidereal Anisotropy in 1 and 11 TeV cosmic rays from the MINOS experiment

    E-print Network

    J. K. de Jong; for the MINOS Collaboration

    2011-11-11

    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$\\pm$1.7(stat.)$\\times 10^{-4}$ and (8.9$\\pm$12.1(stat.))$^{\\circ}$, and at 11 TeV are 3.8$\\pm$0.5(stat.)$\\times 10^{-4}$ and (27.2$\\pm$7.2(stat.))$^{\\circ}$.

  20. 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}.

  1. FERMI-LARGE AREA TELESCOPE OBSERVATIONS OF THE EXCEPTIONAL GAMMA-RAY OUTBURSTS OF 3C 273 IN 2009 SEPTEMBER

    SciTech Connect

    Abdo, A. A. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bouvier, A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d'Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bonamente, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Brigida, M. [Dipartimento di Fisica 'M. Merlin' dell'Universita e del Politecnico di Bari, I-70126 Bari (Italy); Bruel, P. [Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Palaiseau (France); Burnett, T. H. [Department of Physics, University of Washington, Seattle, WA 98195-1560 (United States)], E-mail: gino.tosti@pg.infn.it, E-mail: enrico.massaro@uniroma1.it (and others)

    2010-05-01

    We present the light curves and spectral data of two exceptionally luminous gamma-ray outbursts observed by the Large Area Telescope experiment on board the Fermi Gamma-ray Space Telescope from 3C 273 in 2009 September. During these flares, having a duration of a few days, the source reached its highest {gamma}-ray flux ever measured. This allowed us to study, in some details, their spectral and temporal structures. The rise and the decay are asymmetric on timescales of 6 hr, and the spectral index was significantly harder during the flares than during the preceding 11 months. We also found that short, very intense flares put out the same time-integrated energy as long, less intense flares like that observed in 2009 August.

  2. The Brightness of Density Structures at Large Solar Elongation Angles: What is Being Observed by STEREO/SECCHI?

    E-print Network

    Lugaz, N; Roussev, I I; Jacobs, C; Manchester, W B; Cohen, O

    2008-01-01

    We discuss features of coronal mass ejections (CMEs) that are specific to heliospheric observations at large elongation angles. Our analysis is focused on a series of two eruptions that occurred on 2007 January 24-25, which were tracked by the Heliospheric Imagers (HIs) onboard STEREO. Using a three-dimensional (3-D) magneto-hydrodynamic simulation of these ejections with the Space Weather Modeling Framework (SWMF), we illustrate how the combination of the 3-D nature of CMEs, solar rotation, and geometry associated with the Thomson sphere results in complex effects in the brightness observed by the HIs. Our results demonstrate that these effects make any in-depth analysis of CME observations without 3-D simulations challenging. In particular, the association of bright features seen by the HIs with fronts of CME-driven shocks is far from trivial. In this Letter, we argue that, on 2007 January 26, the HIs observed not only two CMEs, but also a dense corotating stream compressed by the CME-driven shocks.

  3. TWO EPOCHS OF VERY LARGE ARRAY OBSERVATIONS OF WATER MASER EMISSION IN THE ACTIVE GALAXY NGC 6240

    SciTech Connect

    Hagiwara, Yoshiaki [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    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.

  4. Insights into the nature of northwest-to-southeast aligned ionospheric wavefronts from contemporaneous Very Large Array and ionosonde observations

    NASA Astrophysics Data System (ADS)

    Helmboldt, J. F.

    2012-07-01

    The results of contemporaneous summer nighttime observations of midlatitude medium scale traveling ionospheric disturbances (MSTIDs) with the Very Large Array (VLA) in New Mexico and nearby ionosondes in Texas and Colorado are presented. Using 132, 20-minute observations, several instances of MSTIDs were detected, all having wavefronts aligned northwest to southeast and mostly propagating toward the southwest, consistent with previous studies of MSTIDs. However, some were also found to move toward the northeast. It was found that both classes of MSTIDs were only found when sporadic-E (Es) layers of moderate peak density (1.5? < ??foEs? < ?3 MHz) were present. Limited fbEs data from one ionosonde suggests that there was a significant amount of structure within the Es layers during observations when foEs > ?3 MHz that was not present when 1.5? < foEs < ?3 MHz. No MSTIDs were observed either before midnight or when the F-region height was increasing at a relatively high rate, even when these Es layers were observed. Combining this result with AE indices which were relatively high at the time (an average of about 300 nT and maximum of nearly 700 nT), it is inferred that both the lack of MSTIDs and the increase in F-region height are due to substorm-induced electric fields. The northeastward-directed MSTIDs were strongest post-midnight during times when the F-region was observed to be collapsing relatively quickly. This implies that these two occurrences are related and likely both caused by rare shifts in F-region neutral wind direction from southwest to northwest.

  5. Attitude maneuvers of a rigid spacecraft in a circular orbit

    Microsoft Academic Search

    Taeyoung Lee; N. Harris McClamroch; Melvin Leok

    2006-01-01

    A global model is presented that can be used to study attitude maneuvers of a rigid spacecraft in a circular orbit about a large central body. The model includes gravity gradient effects that arise from the non-uniform gravity field and characterizes the spacecraft attitude with respect to the uniformly rotating local vertical local horizontal coordinate frame. An accurate computational approach

  6. Attitude Maneuvers of a Rigid Spacecraft in a Circular Orbit

    Microsoft Academic Search

    Taeyoung Lee; Melvin Leok; N. Harris McClamroch

    2005-01-01

    A global model is presented that can be used to study attitude maneuvers of a rigid spacecraft in a circular orbit about a large central body. The model includes gravity gradient effects that arise from the non-uniform gravity field and characterizes the spacecraft attitude with respect to the uniformly rotating local vertical local horizontal coordinate frame. An accurate computational approach

  7. What Causes the Circular Polarization in Pulsars? Radio Pulsars

    E-print Network

    Melrose, Don

    with the cyclotron resonance region. 1. Introduction The circular polarization (CP) of pulsar radio emission, and the characteristics of the CP are well documented (Han et al. 1998). Data on ,the complete polarization of single pulses (Ekers & Moffat 1968; Clark & Smith 1969)imply that the CP can be large and variable from pulse

  8. Suspended sediment transport under seiches in circular and elliptical basins

    E-print Network

    Hogg, Andrew

    Suspended sediment transport under seiches in circular and elliptical basins David Pritcharda often experience large-scale oscillatory motions (seiching). As a simple model of such flow, we of the morphodynamical importance of seiching motions and also reveal a characteristic pattern of net erosion

  9. Broadband circular polarizer formed by stacked plasmonic metasurfaces

    Microsoft Academic Search

    Yang Zhao; Andrea Alù

    2011-01-01

    Recent ideas involving plasmonic metamaterials have been put forward to enhance the overall bandwidth of operation of quarter-wave plates for circular polarization detection. The proposed metamaterial geometries are inherently complex to realize and difficult to scale beyond the near-infrared frequencies. Here, we show how proper stacks of lithographically printed plasmonic metasurfaces with simple patterns may provide large extinction ratios for

  10. 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.

  11. Lupus I Observations from the 2010 Flight of the Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry

    NASA Astrophysics Data System (ADS)

    Matthews, Tristan G.; Ade, Peter A. R.; Angilè, Francesco E.; Benton, Steven J.; Chapin, Edward L.; Chapman, Nicholas L.; Devlin, Mark J.; Fissel, Laura M.; Fukui, Yasuo; Gandilo, Natalie N.; Gundersen, Joshua O.; Hargrave, Peter C.; Klein, Jeffrey; Korotkov, Andrei L.; Moncelsi, Lorenzo; Mroczkowski, Tony K.; Netterfield, Calvin B.; Novak, Giles; Nutter, David; Olmi, Luca; Pascale, Enzo; Poidevin, Frédérick; Savini, Giorgio; Scott, Douglas; Shariff, Jamil A.; Soler, Juan Diego; Tachihara, Kengo; Thomas, Nicholas E.; Truch, Matthew D. P.; Tucker, Carole E.; Tucker, Gregory S.; Ward-Thompson, Derek

    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 ?m. 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.

  12. THEMIS observations of the magnetopause electron diffusion region and magnetospheric separatrix: Large amplitude waves and heated particles

    NASA Astrophysics Data System (ADS)

    Tang, X.; Cattell, C. A.; Wilson, L. B., III

    2013-12-01

    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. [2012] at the subsolar magnetopause [Tang et al., 2013] as well as near the magnetospheric separatrix using data from the THEMIS satellites. A wide range of wave modes identified as whistler mode waves, electrostatic solitary waves, lower hybrid waves, electrostatic electron cyclotron waves and electrostatic ion harmonic waves are often simultaneously observed 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. Evidence of perpendicular ion heating (< 100 eV) by the electrostatic ion harmonic waves has been found near the magnetospheric separatrix. The whistler mode waves, which are at the electron scale and enable us to probe electron dynamics in the diffusion region were analyzed in detail. The energetic electrons (˜30 keV) within the electron diffusion region have anisotropic distributions with Te?/Te? > 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. Large Scale CO Observations of a Far-Infrared Loop in Pegasus; Detection of a Large Number of Very Small Molecular Clouds Possibly Formed via Shocks

    E-print Network

    Hiroaki Yamamoto; Akiko Kawamura; Kengo Tachihara; Norikazu Mizuno; Toshikazu Onishi; Yasuo Fukui

    2006-01-15

    We have carried out large scale 12CO and 13CO observations with a mm/sub-mm telescope NANTEN toward a loop-like structure in far infrared whose angular extent is about 20x20 degrees around (l, b) ~ (109, -45) in Pegasus. The 12CO distribution is found to consist of 78 small clumpy clouds whose masses range from 0.04 Mo to 11 Mo. About 83% of the 12CO clouds have very small masses less than 1.0 Mo. 13CO emission shown in the 19 of the 78 12CO clouds was detected in the region where the column density of H2 derived from 12CO is greater than 5x10(20) cm(-2), corresponding to Av of ~ 1 mag, which takes into account that of HI. We find no indication of star formation in these clouds in IRAS and 2MASS Point Source Catalogs. The very low mass clouds, M clouds of ~ 100 Mo. A comparison with a theoretical work on molecular cloud formation (Koyama & Inutsuka 2002) suggests that the very low-mass clouds may have been formed in the shocked layer through the thermal instability. The star HD886 (B2IV) may be the source of the mechanical luminosity via stellar winds to create shocks, forming the loop-like structure where the very low-mass clouds are embedded.

  14. New Interstellar Ammonia Maser Emission in NGC 7538: Expanded Very Large Array and Green Bank Telescope Observations

    NASA Astrophysics Data System (ADS)

    Seojin Kim, Stella; Hoffman, I. M.

    2011-05-01

    Using the Expanded Very Large Array and the Green Bank Telescope, we have observed the ammonia maser in NGC 7538 for the first time since its discovery in 1984. We present the first interferometric observations of the maser, demonstrating the nonthermal nature of the emission and providing a precise location for the maser in the star-forming complex. We also detect several new maser components that have appeared in the last 25 years. This maser is the nonmetastable (J,K) = (9,6) transition of ammonia at 18.5 GHz. We present a single epoch of observation with the EVLA in September 2010 and two epochs with the GBT in December 2010 and January 2011, with the following results: (1) We find several new emission peaks near -56 km/s in addition to the known emission near -60 km/s. All of the emission features have flux densities of approximately 1 Jy. (2) In GBT observing epochs separated by six weeks we do not find any of the maser features to vary in intensity. (3) In both the GBT and EVLA data, we resolve spectrally the emission feature near -60 km/s into two peaks and the emission features near -56 km/s into at least four peaks, all with widths of approximately 0.5 km/s. (4) At the three-arcsecond angular resolution of the EVLA observations, we find all of the maser features to be spatially coincident with each other on the sky and to lie at the location of the compact HII region IRS1. (5) The maser features are angularly unresolved in the EVLA images, indicating a lower limit of 500 K brightness temperatures. Given equivalent thermal line widths of 100 K, these brightness temperatures indicate nonthermal emission. This work is supported by the Thomas Penrose Bennett Prize Fund and the Lovejoy Science Fund of St. Paul's School.

  15. Marked difference in conformational fluctuation between giant DNA molecules in circular and linear forms

    NASA Astrophysics Data System (ADS)

    Iwaki, Takafumi; Ishido, Tomomi; Hirano, Ken; Lazutin, Alexei A.; Vasilevskaya, Valentina V.; Kenmotsu, Takahiro; Yoshikawa, Kenichi

    2015-04-01

    We performed monomolecular observations on linear and circular giant DNAs (208 kbp) in an aqueous solution by the use of fluorescence microscopy. The results showed that the degree of conformational fluctuation in circular DNA was ca. 40% less than that in linear DNA, although the long-axis length of circular DNA was only 10% smaller than that of linear DNA. Additionally, the relaxation time of a circular chain was shorter than that of a linear chain by at least one order of magnitude. The essential features of this marked difference between linear and circular DNAs were reproduced by numerical simulations on a ribbon-like macromolecule as a coarse-grained model of a long semiflexible, double-helical DNA molecule. In addition, we calculated the radius of gyration of an interacting chain in a circular form on the basis of the mean field model, which provides a better understanding of the present experimental trend than a traditional theoretical equation.

  16. 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; Sutanudjaja, Edwin; Renzullo, Luigi; Sterk, Geert; Schellekens, Jaap; Bierkens, Marc

    2015-04-01

    The coarse spatial resolution of global hydrological models (typically > 0.25o) often 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-tunes river models. A possible solution to the problem may be to drive the coarse resolution models with high-resolution meteorological data as well as to assimilate ground-based and remotely-sensed observations of key water cycle variables. While this would improve the modelling resolution of the global model, the impact of prediction accuracy remains largely an open question. In this study we investigated the impact that assimilating streamflow and satellite soil moisture observations have on global hydrological model estimation, driven by coarse- and high-resolution meteorological observations, for the Murrumbidgee river basin in Australia. The PCR-GLOBWB global hydrological model is forced with downscaled global climatological data (from 0.5o downscaled to 0.1o resolution) obtained from the WATCH Forcing Data (WFDEI) and local high resolution gauging station based gridded datasets (0.05o), sourced from the Australian Bureau of Meteorology. Downscaled satellite derived soil moisture (from 0.5o downscaled to 0.1o resolution) from AMSR-E and streamflow observations collected from 25 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 climatological data. Results show that the assimilation of streamflow observations result in the largest improvement of the model estimates. The joint assimilation of both streamflow and downscaled soil moisture observations leads to further improved in streamflow simulations (10% reduction in RMSE), mainly in the headwater catchments (up to 10,000 km2). Results also show that the added contribution of data assimilation, for both soil moisture and streamflow, is more pronounced when the global meteorological data are used to force the models. This is caused by the higher uncertainty and coarser resolution of the global forcing. This study demonstrates that it is possible to improve hydrological simulations forced by coarse resolution meteorological data with downscaled satellite soil moisture and streamflow observations and bring them closer to a hydrological model forced with local climatological data. These findings are important in light of the efforts that are currently done to go to global hyper-resolution modelling and can significantly help to advance this research.

  17. 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.

  18. Oscillation-induced sand ripples in a circular geometry Germain Rousseaux*

    E-print Network

    Wesfreid, José Eduardo

    Oscillation-induced sand ripples in a circular geometry Germain Rousseaux* Laboratoire J; published 7 July 2008 This study deals with the observation of sand ripples in a circular geometry under.57.Gc, 47.20.Ma, 47.54.De Ripples are sand patterns which are built by the to and fro motion induced

  19. Synthesis and two-dimensional electrophoretic analysis of mixed populations of circular and linear RNAs

    Microsoft Academic Search

    Paul A. Feldstein; Laurene Levy; John W. Randles; Robert A. Owens

    1997-01-01

    Spontaneous cleavage of the less abundant form of tobacco ringspot virus satellite RNA is readily reversible. Capitalizing on earlier observations by Feldstein and Bruening that small 'mini-monomer' RNAs derived from this molecule and containing little more than covalently attached ribozyme and substrate cleavage products are able to efficiently circularize, we have constructed a series of self-circularizing RNAs of precisely known

  20. Spectra of Turbulence in Wakes behind Circular Cylinders

    Microsoft Academic Search

    Mahinder S. Uberoi; Peter Freymuth

    1969-01-01

    One-dimensional spectra of turbulent wakes behind circular cylinders are measured in the range of 50-800 diam downstream of the cylinders and for a Reynolds number range of 320-95 000. The spectra of large-scale (low-wavenumber) turbulence are anisotropic and dynamically similar. The small-scale turbulence is locally isotropic and an inertial subrange was found for large Reynolds numbers. A proposed formula describes

  1. Circular Polarization of Transmitted Light by Sapphirinidae Copepods

    E-print Network

    Rosen, Joseph

    observed occurring naturally only near the water surface [3,4]. Among animals, the production of circularly. versicolor firefly larvae, in reflections from beetles of the Scarabaeidae family, in Panulirus argus microfibril layers in the exocuticle of beetles belonging to the Scarabaeidae family is usually left handed [5

  2. Observations of the Young Supernova Remnant RX J1713.7-3946 with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Chaty, S.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Cillis, A. N.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Corbel, S.; Cutini, S.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Digel, S. W.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Favuzzi, C.; Ferrara, E. C.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Fukui, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hayashi, K.; Hays, E.; Horan, D.; Jackson, M. S.; Jóhannesson, G.; Johnson, A. S.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mignani, R. P.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Naumann-Godo, M.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Orlando, E.; Ormes, J. F.; Paneque, D.; Parent, D.; Pelassa, V.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pohl, M.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, O.; Reposeur, T.; Ritz, S.; Romani, R. W.; Roth, M.; Sadrozinski, H. F.-W.; Saz Parkinson, P. M.; Sgrò, C.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Torres, D. F.; Tosti, G.; Tramacere, A.; Troja, E.; Uchiyama, Y.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yamamoto, H.; Yamazaki, R.; Yang, Z.; Ziegler, M.

    2011-06-01

    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 0fdg55 ± 0fdg04 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 ? = 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.

  3. Observation of energetic-ion losses induced by various MHD instabilities in the Large Helical Device (LHD)

    SciTech Connect

    Ogawa, K. [Nagoya University, Japan; Isobe, M. [National Institute for Fusion Science, Toki, Japan; Toi, K. [National Institute for Fusion Science, Toki, Japan; Watanabe, F. [Kyoto University, Japan; Spong, Donald A [ORNL; Shimizu, A. [National Institute for Fusion Science, Toki, Japan; Osakabe, M. [National Institute for Fusion Science, Toki, Japan; Ohdachi, S. [National Institute for Fusion Science, Toki, Japan; Sakakibara, S. [National Institute for Fusion Science, Toki, Japan

    2010-01-01

    Energetic-ion losses induced by toroidicity-induced Alfven 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 = 190keV down to 130 keV, while RICs expel energetic ions of E = 190 keV down to similar 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.

  4. Harmonic generation by circularly polarized laser beams propagating in plasma

    NASA Astrophysics Data System (ADS)

    Agrawal, Ekta; Hemlata, Jha, Pallavi

    2015-04-01

    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.

  5. Circular polarization in star- formation regions: implications for biomolecular homochirality

    PubMed

    Bailey; Chrysostomou; Hough; Gledhill; McCall; Clark; Menard; Tamura

    1998-07-31

    Strong infrared circular polarization resulting from dust scattering in reflection nebulae in the Orion OMC-1 star-formation region has been observed. Circular polarization at shorter wavelengths might have been important in inducing chiral asymmetry in interstellar organic molecules that could be subsequently delivered to the early Earth by comets, interplanetary dust particles, or meteors. This could account for the excess of L-amino acids found in the Murchison meteorite and could explain the origin of the homochirality of biological molecules. PMID:9685254

  6. Observations of the refraction of microbaroms generated by large maritime storms by the wind field of the generating storm

    NASA Astrophysics Data System (ADS)

    Blom, Philip; Waxler, Roger; Frazier, Wm. Garth; Talmadge, Carrick

    2014-06-01

    Microbaroms are a continuous infrasonic signal in the 0.15 to 0.3 Hz band caused by the collision of oceanic surface waves of equal period. Such signals are often generated by large maritime storms. Current formulation of the generation mechanism predicts that the microbarom source location due to a large maritime storm in the open ocean is generally located several hundreds of kilometers from the eye of the storm. Assuming such a source location to be correct, propagation of the microbaroms along paths which pass near the storm center as well as those which propagate away from the storm structure have been examined using geometric acoustics. Microbarom propagation paths which pass near the storm center are refracted by the storm winds and are found to have back azimuths directed toward a virtual source around the storm center. Microbarom propagation paths which do not pass near the storm center are found to have back azimuths directed toward the actual source region. To validate these predictions, data from microbarom signals generated by hurricanes in the Atlantic Ocean have been collected along the east coast of the United States during the 2010 and 2011 Atlantic hurricane seasons. Data from several storm events are presented here for comparison with model predictions. In general, the observations are in agreement with the predictions of the propagation model.

  7. 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.

  8. Chiral plasmonic DNA nanostructures with switchable circular dichroism.

    PubMed

    Schreiber, Robert; Luong, Ngoc; Fan, Zhiyuan; Kuzyk, Anton; Nickels, Philipp C; Zhang, Tao; Smith, David M; Yurke, Bernard; Kuang, Wan; Govorov, Alexander O; Liedl, Tim

    2013-01-01

    Circular dichroism spectra of naturally occurring molecules and also of synthetic chiral arrangements of plasmonic particles often exhibit characteristic bisignate shapes. Such spectra consist of peaks next to dips (or vice versa) and result from the superposition of signals originating from many individual chiral objects oriented randomly in solution. Here we show that by first aligning and then toggling the orientation of DNA-origami-scaffolded nanoparticle helices attached to a substrate, we are able to reversibly switch the optical response between two distinct circular dichroism spectra corresponding to either perpendicular or parallel helix orientation with respect to the light beam. The observed directional circular dichroism of our switchable plasmonic material is in good agreement with predictions based on dipole approximation theory. Such dynamic metamaterials introduce functionality into soft matter-based optical devices and may enable novel data storage schemes or signal modulators. PMID:24336125

  9. Single-Domain Circular Nanomagnets

    Microsoft Academic Search

    R. P. Cowburn; D. K. Koltsov; A. O. Adeyeye; M. E. Welland; D. M. Tricker

    1999-01-01

    The magnetic properties of deep submicron circular nanomagnets fabricated by high-resolution electron beam lithography from Supermalloy \\\\(Ni80Fe14Mo5\\\\) have been studied as a function of both diameter (500-55 nm) and thickness (6-15 nm). A high sensitivity magneto-optical method has been used to measure the hysteresis loops of these nanomagnets. An experimental phase diagram in diameter and thickness has thus been produced

  10. 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.

  11. Dark Matter Constraints from Observations of 25 Milky Way Satellite Galaxies with the Fermi Large Area Telescope

    E-print Network

    :,; 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; Bregeon, J; Brigida, M; Bruel, P; Buehler, R; Buson, S; Caliandro, G A; Cameron, R A; Caragiulo, M; Caraveo, P A; Cecchi, C; Charles, E; Chekhtman, A; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; D'Ammando, F; de Angelis, A; Dermer, C D; Digel, S W; Silva, E do Couto e; Drell, P S; Drlica-Wagner, A; Essig, R; Favuzzi, C; Ferrara, E C; Franckowiak, A; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Giglietto, N; Giroletti, M; Godfrey, G; Gomez-Vargas, G A; Grenier, I A; Guiriec,; Gustafsson, M; Hayashida, M; Hays, E; Hewitt, J; Hughes, R E; Jogler, T; Kamae, T; Knödlseder, J; Kocevski, D; Kuss, M; Larsson,; Latronico, L; Garde, M Llena; Longo, F; Loparco, F; Lovellette, M N; Lubrano, P; Martinez, G; Mayer, M; Mazziotta, M N; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nemmen, R; Nuss, E; Ohsugi, T; Orlando, E; Ormes, J F; Perkins, J S; Piron, F; Pivato, G; Porter, T A; Rainò, S; Rando, R; Razzano, M; Razzaque, S; Reimer, A; Reimer, O; Ritz, S; Sànchez-Conde, M; Sehgal, N; Sgrò, C; Siskind, E J; Spinelli, P; Strigari, L; Suson, D J; Tajima, H; Takahashi, H; Thayer, J B; Tibaldo, L; Tinivella, M; Torres, D F; Uchiyama, Y; Usher, T L; Vandenbroucke, J; Vianello, G; Vitale, V; Werner, M; Winer, B L; Wood, K S; Wood, M; Zaharijas, G; Zimmer, 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 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. W...

  12. Dark Matter Constraints from Observations of 25 Milky Way Satellite Galaxies with the Fermi Large Area Telescope

    E-print Network

    The Fermi-LAT Collaboration; :; M. Ackermann; A. Albert; B. Anderson; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; K. Bechtol; R. Bellazzini; E. Bissaldi; E. D. Bloom; E. Bonamente; A. Bouvier; T. J. Brandt; J. Bregeon; M. Brigida; P. Bruel; R. Buehler; S. Buson; G. A. Caliandro; R. A. Cameron; M. Caragiulo; P. A. Caraveo; C. Cecchi; E. Charles; A. Chekhtman; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; J. Conrad; F. D'Ammando; A. de Angelis; C. D. Dermer; S. W. Digel; E. do Couto e Silva; P. S. Drell; A. Drlica-Wagner; R. Essig; C. Favuzzi; E. C. Ferrara; A. Franckowiak; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Giglietto; M. Giroletti; G. Godfrey; G. A. Gomez-Vargas; I. A. Grenier; S. Guiriec; M. Gustafsson; M. Hayashida; E. Hays; J. Hewitt; R. E. Hughes; T. Jogler; T. Kamae; J. Knödlseder; D. Kocevski; M. Kuss; . Larsson; L. Latronico; M. Llena Garde; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; G. Martinez; M. Mayer; M. N. Mazziotta; P. F. Michelson; W. Mitthumsiri; T. Mizuno; A. A. Moiseev; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Murgia; R. Nemmen; E. Nuss; T. Ohsugi; E. Orlando; J. F. Ormes; J. S. Perkins; F. Piron; G. Pivato; T. A. Porter; S. Rainò; R. Rando; M. Razzano; S. Razzaque; A. Reimer; O. Reimer; S. Ritz; M. Sànchez-Conde; N. Sehgal; C. Sgrò; E. J. Siskind; P. Spinelli; L. Strigari; D. J. Suson; H. Tajima; H. Takahashi; J. B. Thayer; L. Tibaldo; M. Tinivella; D. F. Torres; Y. Uchiyama; T. L. Usher; J. Vandenbroucke; G. Vianello; V. Vitale; M. Werner; B. L. Winer; K. S. Wood; M. Wood; G. Zaharijas; S. Zimmer

    2014-02-19

    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.

  13. THE VELA-X PULSAR WIND NEBULA REVISITED WITH FOUR YEARS OF FERMI LARGE AREA TELESCOPE OBSERVATIONS

    SciTech Connect

    Grondin, M.-H. [Max-Planck-Institut fuer Kernphysik, P.O. Box 103980, D-69029 Heidelberg (Germany); Romani, R. W. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Lemoine-Goumard, M.; Reposeur, T. [Universite Bordeaux 1, CNRS/IN2p3, Centre d'Etudes Nucleaires de Bordeaux Gradignan, F-33175 Gradignan (France); Guillemot, L. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Harding, A. K., E-mail: mgrondin@irap.omp.eu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    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.

  14. 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.

  15. Large grains in disks around young stars: ATCA observations of WW Cha, RU Lup, and CS Cha

    E-print Network

    Dave Lommen; Sarah Maddison; Chris Wright; Ewine van Dishoeck; David Wilner; Tyler Bourke

    2008-12-19

    Grains in disks around young stars grow from interstellar submicron sizes to planetesimals over the course of several Myr. Thermal emission of large grains or pebbles can be best observed at cm wavelengths. However, other emission mechanisms can contribute. We aim to determine the mechanisms of cm emission for 3 T Tauri stars. WW Cha and RU Lup were recently found to have grain growth at least up to mm sizes in their circumstellar disks. CS Cha has similar indications for grain growth in its circumbinary disk. The T Tauri stars WW Cha and RU Lup were monitored over several years at mm and cm wavelengths, using ATCA. The new ATCA 7 mm system was also used to observe CS Cha. WW Cha was detected on several occasions at 7 and 16 mm. We obtained one detection of WW Cha at 3 cm and upper limits only at 6 cm. The emission at 16 mm was stable over days, months and years, but the emission at 3 cm is found to be variable. RU Lup was detected at 7 mm. It was observed at 16 mm 3 times and at 3 and 6 cm 4 times and found to be variable in all 3 wavebands. CS Cha was detected at 7 mm, but the S/N was too low to resolve the gap in the circumbinary disk. The emission at 3, 7 and 16 mm for WW Cha is well explained by thermal emission from mm and cm-sized pebbles. The cm spectral index is consistent with the emission from an optically-thick ionised wind, but the high variability of the cm emission points to a non-thermal contribution. The SEDs of RU Lup and CS Cha from 1 to 7 mm are consistent with thermal emission from mm-sized grains. The variability of the longer-wavelength emission for RU Lup and the negative spectral index suggest non-thermal emission.

  16. Astronomical sources of circularly polarized light and the origin of homochirality.

    PubMed

    Bailey, J

    2001-01-01

    Possible astronomical sources of ultraviolet circularly polarized light (UVCPL) which might be responsible for enantiomeric selection in interstellar organic molecules are considered, Synchrotron radiation from magnetic neutron stars has been suggested as a possible source of UVCPL. However, synchrotron radiation in these situations is not predicted to be strongly circularly polarized. Very few such sources show optical synchrotron radiation and in the few that do circular polarization has not been observed. Magnetic white dwarfs and white dwarf binaries (Polars) can be highly circularly polarized but any effect on molecular clouds and star formation regions must rely on rare chance encounters. Recent observations show that substantial levels of circular polarization are present in reflection nebulae in star formation regions. This mechanism produces polarized light exactly when and where it is needed in regions where star formation is occurring and organic molecules are known to be present. PMID:11296520

  17. Structural Concepts Study of Non-circular Fuselage Configurations

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, Vivel

    1996-01-01

    A preliminary study of structural concepts for noncircular fuselage configurations is presented. For an unconventional flying-wing type aircraft, in which the fuselage is inside the wing, multiple fuselage bays with non-circular sections need to be considered. In a conventional circular fuselage section, internal pressure is carried efficiently by a thin skin via hoop tension. If the section is non-circular, internal pressure loads also induce large bending stresses. The structure must also withstand additional bending and compression loads from aerodynamic and gravitational forces. Flat and vaulted shell structural configurations for such an unconventional, non-circular pressurized fuselage of a large flying-wing were studied. A deep honeycomb sandwich-shell and a ribbed double-wall shell construction were considered. Combinations of these structural concepts were analyzed using both analytical and simple finite element models of isolated sections for a comparative conceptual study. Weight, stress, and deflection results were compared to identify a suitable configuration for detailed analyses. The flat sandwich-shell concept was found preferable to the vaulted shell concept due to its superior buckling stiffness. Vaulted double-skin ribbed shell configurations were found to be superior due to their weight savings, load diffusion, and fail-safe features. The vaulted double-skin ribbed shell structure concept was also analyzed for an integrated wing-fuselage finite element model. Additional problem areas such as wing-fuselage junction and pressure-bearing spar were identified.

  18. Large-scale, prospective, observational studies in patients with psoriasis and psoriatic arthritis: A systematic and critical review

    PubMed Central

    2011-01-01

    Background Observational studies, if conducted appropriately, play an important role in the decision-making process providing invaluable information on effectiveness, patient-reported outcomes and costs in a real-world environment. We conducted a systematic review of large-scale, prospective, cohort studies with the aim of (a) summarising design characteristics, the interventions or aspects of the disease studied and the outcomes measured and (b) investigating methodological quality. Methods We included prospective, cohort studies which included at least 100 adults with psoriasis or psoriatic arthritis. Studies were identified through searches in electronic databases (Pubmed, Medline, Cochrane library, Centre for Reviews and Dissemination). Information on study characteristics were extracted and tabulated and quality assessment, using a checklist of 18 questions, was conducted. Results Thirty five papers covering 16 cohorts met the inclusion criteria. There were ten treatment-related studies, only two of which provided a comparison between treatments, and six non-treatment studies which examined a number of characteristics of the disease including mortality, morbidity, cost of illness and health-related quality of life. All studies included a clinical outcome measure and 11 included patient-reported outcomes, however only two studies reported information on patient utilities and two on costs. The quality of the assessed studies varied widely. Studies did well on a number of quality assessment questions including having clear objectives, documenting selection criteria, providing a representative sample, defining interventions/characteristics under study, defining and using appropriate outcomes, describing results clearly and using appropriate statistical tests. The quality assessment criteria least adhered to involved questions regarding sample size calculations, describing potential selection bias, defining and adjusting for confounders and losses to follow-up, and defining and describing a comparison group. Conclusion The review highlights the need for well designed prospective observational studies on the effectiveness, patient-reported outcomes and economic impact of treatment regimes for patients with psoriasis and psoriatic arthritis in a real-world environment. PMID:21453459

  19. Numerical investigations of transition in hypersonic flows over circular cones

    NASA Astrophysics Data System (ADS)

    Husmeier, Frank

    This thesis focuses on secondary instability mechanisms of high-speed boundary layers over cones with a circular cross section. Hypersonic transition investigations at Mach 8 are performed using Direct Numerical Simulations (DNS). At wind-tunnel conditions, these simulations allow for comparison with experimental measurements to verify fundamental stability characteristics. To better understand geometrical influences, flat-plate and cylindrical geometries are studied using after-shock conditions of the conical investigations. This allows for a direct comparison with the results of the sharp cone to evaluate the influence of the spanwise curvature and the cone opening angle. The ratio of the boundary-layer thickness to the spanwise radius is used to determine the importance of spanwise curvature effects. When advancing in the downstream direction the radius increases linearly while the boundary-layer thickness stays almost constant. Hence, spanwise curvature effects are strongest close to the nose and decrease in downstream direction. Their influences on the secondary instability mechanisms provide some rudimentary guidance in the design of future high-speed air vehicles. In experiments, blunting of the nose tip of the circular cone results in an increase in critical Reynolds number (c.f. Stetson et al. (1984)). However, once a certain threshold of the nose radius is exceeded, the critical Reynolds number decreases even to lower values than for the sharp cone. So far, conclusive explanations for this behavior could not be derived based on the available experimental data. Therefore, here DNS is used to study the effect of nose bluntness on secondary instability mechanisms in order to shed light on the underlying flow physics. To this end, three different nose tip radii are considered-the sharp cone, a small nose radius and a large nose radius. A small nose radius moves the transition on-set downstream, while for a large nose radius the so-called transition reversal is observed. Experimentalists hold influences of the entropy layer responsible but detailed numerical studies may lead to alternate conclusions.

  20. Fermi-Large Area Telescope Observations of the Exceptional Gamma-ray Flare from 3C 279 in 2015 June

    E-print Network

    Paliya, Vaidehi S

    2015-01-01

    An exceptional $\\gamma$-ray outburst from 3C 279 is detected by {\\it Fermi}-Large Area Telescope (LAT) in 2015 June. In the energy range of 0.1$-$300 GeV, the highest flux measured is (39.1$\\pm$2.5) $\\times$ 10$^{-6}$ \\phflux, which is the highest $\\gamma$-ray flux ever detected from 3C 279, exceeding the previous historically brightest flare observed by {\\it EGRET} in 1996. The high activity period consists of three major flares with the last one being the brightest. All but one flares show a faster rise and slower decay pattern and at the peak of the activity, the $\\gamma$-ray spectrum is found to show a clear signature of break/curvature. The obtained spectral parameters hint for the peak of the inverse Compton emission to lie in the LAT energy range (around $\\sim$1 GeV) which is in contrast to that seen during the 2013 December and 2014 April $\\gamma$-ray flares of 3C 279. From the $\\gamma\\gamma$ pair opacity arguments, the minimum Doppler factor is estimated to be 14 and the location of the $\\gamma$-ray ...

  1. Large volume collapse observed in the phase transition in cubic PbCrO[subscript 3] perovskite

    SciTech Connect

    Xiao, Wansheng; Tan, Dayong; Xiong, Xiaolin; Liu, Jing; Xu, Jian (Chinese Aca. Sci.)

    2010-08-27

    When cubic PbCrO{sub 3} perovskite (Phase I) is squeezed up to {approx}1.6 GPa at room temperature, a previously undetected phase (Phase II) has been observed with a 9.8% volume collapse. Because the structure of Phase II can also be indexed into a cubic perovskite as Phase I, the transition between Phases I and II is a cubic to cubic isostructural transition. Such a transition appears independent of the raw materials and synthesizing methods used for the cubic PbCrO{sub 3} perovskite sample. In contrast to the high-pressure isostructural electronic transition that appears in Ce and SmS, this transition seems not related with any change of electronic state, but it could be possibly related on the abnormally large volume and compressibility of the PbCrO{sub 3} Phase I. The physical mechanism behind this transition and the structural and electronic/magnetic properties of the condensed phases are the interesting issues for future studies.

  2. Observations of structuring in the downstream region of a large spherical model in a laboratory simulated solar wind plasma

    NASA Technical Reports Server (NTRS)

    Intriligator, D. S.; Steele, G. R.

    1982-01-01

    The effects of inserting a spherical conducting model, large in comparison with the Debye length, into a free streaming high-energy 1 kV) unmagnetized hydrogen plasma are investigated in order to measure energies and compositions directly relevant to solar wind and astrophysical plasma phenomena. Holding the incident plasma parameters constant, transverse profiles of the net Langmuir probe current are plotted at various locations downstream in the model wake and are divided into three regions (the shadow, transition, and boundary). Results attributable to the use of a high-energy plasma show that enhancements in the shadow exist at downstream locations where the Mach ratio is less than one, and turbulence exists in the transition region on the shadow edges and outside in the boundary region. In addition, a small current enhancement is found in the boundary and can be attributed to the plasma/model interaction. It is concluded that many similar features observed by spacecraft downstream from planetary bodies are relatively permanent and are due to the intrinsic nature of the interaction between the solar wind plasma and the obstacle.

  3. Characteristics of fire-generated gas emission observed during a large peatland fire in 2009 at Kalimantan, Indonesia

    NASA Astrophysics Data System (ADS)

    Hamada, Yohei; Darung, Untung; Limin, Suwido H.; Hatano, Ryusuke

    2013-08-01

    To investigate the characteristics of gas emissions from a tropical peatland fire, ground-level measurement of fire-generated gases was conducted during a large fire event in Kalimantan, Indonesia in 2009. Concentrations of CO and CH4 showed positive linear correlations with that of CO2. The relationship between concentrations of N2O and CO2 were divided into two parts, suggesting the influence of additional N2O generation during sample storage. The CO2-normalized emission ratio was calculated for CO, CH4, and N2O. The molar ratio of these fire-generated gas emissions was summarized as CO2:CO:CH4:N2O = 1.00:0.382:0.0261:0.000156, whereas the emission ratio calculated on the global warming potential (GWP) basis was CO2:CH4:N2O = 1.00:0.237:0.0465. The GWP emission based on this ratio was 87.8-91.2% of a simple evaluation in which all carbon was assumed to be emitted as CO2. This is the first trial to evaluate the emission ratios of major greenhouse gases on the basis of ground-level observation during an actual tropical peatland fire.

  4. The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. XI. Lupus Observed With IRAC and MIPS

    E-print Network

    Merin, Bruno; Spezzi, Loredana; Alcala, Juan M; Evans, Neal J; Harvey, Paul M; Chapman, Nicholas; Huard, Tracy; van Dishoeck, Ewine F; Comeron, Fernando

    2008-01-01

    We present c2d Spitzer/IRAC observations of the Lupus I, III and IV dark clouds and discuss them in combination with optical and near-infrared and c2d MIPS data. With the Spitzer data, the new sample contains 159 stars, 4 times larger than the previous one. It is dominated by low- and very-low mass stars and it is complete down to M $\\approx$ 0.1M$_\\odot$. We find 30-40 % binaries with separations between 100 to 2000 AU with no apparent effect in the disk properties of the members. A large majority of the objects are Class II or Class III objects, with only 20 (12%) of Class I or Flat spectrum sources. The disk sample is complete down to ``debris''-like systems in stars as small as M $\\approx$ 0.2 M$_\\odot$ and includes sub-stellar objects with larger IR excesses. The disk fraction in Lupus is 70 -- 80%, consistent with an age of 1 -- 2 Myr. However, the young population contains 20% optically thick accretion disks and 40% relatively less flared disks. A growing variety of inner disk structures is found for l...

  5. Lupus I Observations from the 2010 Flight of the Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry

    E-print Network

    Matthews, Tristan G; Angilè, Francesco E; Benton, Steven J; Chapin, Edward L; Chapman, Nicholas L; Devlin, Mark J; Fissel, Laura M; Fukui, Yasuo; Gandilo, Natalie N; Gundersen, Joshua O; Hargrave, Peter C; Klein, Jeffrey; Korotkov, Andrei L; Moncelsi, Lorenzo; Mroczkowski, Tony K; Netterfield, Calvin B; Novak, Giles; Nutter, David; Olmi, Luca; Pascale, Enzo; Poidevin, Frédérick; Savini, Giorgio; Scott, Douglas; Shariff, Jamil A; Soler, Juan Diego; Tachihara, Kengo; Thomas, Nicholas E; Truch, Matthew D P; Tucker, Carole E; Tucker, Gregory S; Ward-Thompson, Derek

    2013-01-01

    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 {\\mu}m. 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,...

  6. Supersymmetric Higgs singlet effects on B-meson flavor-changing neutral current observables at large tan{beta}

    SciTech Connect

    Hodgkinson, Robert N. [School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); High Energy Physics Group, Dept. ECM, Univ. de Barcelona, Av. Diagonal 647, E-08028 Barcelona, Catalonia (Spain); Pilaftsis, Apostolos [School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)

    2008-10-01

    Higgs singlet superfields are usually present in most extensions of the minimal supersymmetric standard model that address the {mu}-problem, such as the next-to-minimal supersymmetric standard model and the minimal nonminimal supersymmetric standard model. Employing a gauge- and flavor- covariant effective Lagrangian formalism, we show how the singlet-Higgs bosons of such theories can have significant contributions to B-meson flavor-changing neutral current observables for large values of tan{beta} > or approx. 50 at the 1-loop level. Illustrative results are presented including effects on the B{sub s} and B{sub d} mass differences and on the rare decay B{sub s}{yields}{mu}{sup +}{mu}{sup -}. In particular, we find that depending on the actual value of the lightest singlet pseudoscalar mass in the next-to-minimal supersymmetric standard model, the branching ratio for B{sub s}{yields}{mu}{sup +}{mu}{sup -} can be enhanced or even suppressed with respect to the standard model prediction by more than 1 order of magnitude.

  7. Prevalence of joint replacement surgery in rheumatoid arthritis patients: cross-sectional analysis in a large observational cohort in Japan.

    PubMed

    Nishino, Jinju; Tanaka, Sakae; Matsui, Toshihiro; Mori, Toshihito; Nishimura, Keita; Eto, Yoshito; Kaneko, Atsushi; Saisho, Koichiro; Yasuda, Masayuki; Chiba, Noriyuki; Yoshinaga, Yasuhiko; Saeki, Yukihiko; Seki, Atsuhito; Tohma, Shigeto

    2009-01-01

    The purpose of this study was to describe the prevalence of total joint arthroplasty (TJA) in Japanese rheumatoid arthritis (RA) patients undergoing conventional drug treatment in a large observational cohort in Japan. A total of 5,177 RA patients were studied for the prevalence of TJA, who were enrolled in the NinJa database during the fiscal year of 2006. The cases of 2,695 RA patients with more than ten years of disease duration were extracted and subjected to further analysis. The prevalence of TJA increased in accordance with the disease duration, and the prevalence was markedly increased after ten years. Among the 2,695 patients with more than ten years of disease duration, 1,431 TJAs were performed in 645 (24.6%) patients. The patients with TJA had higher disease activity than those without TJA. In this cross-sectional study, TJAs were performed in approximately a quarter of the Japanese RA patients with more than ten years of disease duration. The result showed that patients with higher disease activity required TJA. PMID:19288170

  8. 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. [Institute of Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria); Vrsnak, B. [Hvar Observatory, Faculty of Geodesy, Kaciceva 26, 1000 Zagreb (Croatia); Nitta, N., E-mail: ines.kienreich@uni-graz.at [LMSAL, 3251 Hanover Street, Palo Alto, CA 94304 (United States)

    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.

  9. SEARCH FOR A MAGNETIC FIELD VIA CIRCULAR POLARIZATION IN THE WOLF-RAYET STAR EZ CMa

    SciTech Connect

    De la Chevrotiere, A.; St-Louis, N.; Moffat, A. F. J. [Departement de Physique, Universite de Montreal and Centre de Recherche en Astrophysique du Quebec (CRAQ), C. P. 6128, succ. centre-ville, Montreal (Quebec) H3C 3J7 (Canada)] [Departement de Physique, Universite de Montreal and Centre de Recherche en Astrophysique du Quebec (CRAQ), C. P. 6128, succ. centre-ville, Montreal (Quebec) H3C 3J7 (Canada); Collaboration: MiMeS Collaboration

    2013-02-20

    We report on the first deep, direct search for a magnetic field via the circular polarization of Zeeman splitting in a Wolf-Rayet (W-R) star. Using the highly efficient ESPaDOnS spectropolarimeter at the Canada-France-Hawaii Telescope, we observed at three different epochs one of the best W-R candidates in the sky expected to harbor a magnetic field, the bright, highly variable WN4 star EZ CMa = WR6 = HD 50896. We looked for the characteristic circular polarization (Stokes V) pattern in strong emission lines that would arise as a consequence of a global, rotating magnetic field with a split monopole configuration. We also obtained nearly simultaneous linear polarization spectra (Stokes Q and U), which are dominated by electron scattering, most likely from a flattened wind with large-scale corotating structures. As the star rotates with a period of 3.766 days, our view of the wind changes, which in turn affects the value of the linear polarization in lines versus continuum at the {approx}0.2% level. Depending on the epoch of observation, our Stokes V data were affected by significant crosstalk from Stokes Q and U to V. We removed this spurious signal from the circular polarization data and experimented with various levels of spectral binning to increase the signal-to-noise ratio of our data. In the end, no magnetic field is unambiguously detected in EZ CMa. Assuming that the star is intrinsically magnetic and harbors a split monopole configuration, we find an upper limit of B {approx} 100 G for the intensity of its field in the line-forming regions of the stellar wind.

  10. Single-Domain Circular Nanomagnets

    NASA Astrophysics Data System (ADS)

    Cowburn, R. P.; Koltsov, D. K.; Adeyeye, A. O.; Welland, M. E.; Tricker, D. M.

    1999-08-01

    The magnetic properties of deep submicron circular nanomagnets fabricated by high-resolution electron beam lithography from Supermalloy \\(Ni80Fe14Mo5\\) have been studied as a function of both diameter (500-55 nm) and thickness (6-15 nm). A high sensitivity magneto-optical method has been used to measure the hysteresis loops of these nanomagnets. An experimental phase diagram in diameter and thickness has thus been produced which identifies a vortex phase and a single-domain phase. The two phases agree well with micromagnetic theory.

  11. ON THE CIRCULAR DICHROISM AND ROTATORY DISPERSION IN CHOLESTERIC LIQUID CRYSTALS WITH A PITCH GRADIENT

    E-print Network

    Boyer, Edmond

    , Università di Ancona, Italy and F. RUSTICHELLI C.C.R. EURATOM, Ispra, Italy and Facolta di Ingegneria in this paper, was observed in crustacean and insect cuticles by Bouligand [3]. 2. Circular dichroism

  12. Observation of a large amplitude wave and inversion layer leading to convective instability in the mesopause region over Fort Collins, CO

    E-print Network

    Observation of a large amplitude wave and inversion layer leading to convective instability; revised 11 April 2002; accepted 6 May 2002; published 14 September 2002. [1] Sodium resonance lidar and largest inversion layer observed in 10 years over Fort Collins, Colorado. The inversion can be decomposed

  13. Geophysical characterization of circular structures in Chubut and Mendoza (Argentina): Impact vs. Volcanism

    NASA Astrophysics Data System (ADS)

    Prezzi, C.; Orgeira, M. J.; Risso, C.; Acevedo, R.; Ponce, F.; Nullo, F.; Martinez, O.; Rabassa, J.; Margonari, L.; Corbella, H.

    2013-05-01

    This work focuses on two main objectives. One of them is to provide information to discern the genesis of the circular structures present in Bajada del Diablo (Chubut, Argentina) considered as impact craters, and the other one is to contribute to a better knowledge of the circular structures located in the volcanic fields of Llancanelo and Payunia (Mendoza, Argentina). Chubut circular structures have been attributed to the collision of an extraterrestrial body, possibly an asteroid. However, doubts persist about their genesis because of the lack of direct geological evidences. Since detailed geomorphological studies have ruled out an origin by wind deflation, the prevailing alternative hypothesis attributes these circular structures to a volcanic process. On the other hand, the study of the volcanic fields of Payunia and Llancanelo (Mendoza) will contribute to the knowledge of the mechanics of hydromagmatic processes in the area, and the origin of circular structures morphologically similar to those located in Chubut. In the Payunia volcanic field at least 27 cones with evidences of hydromagmatism, in a field of more than 800 pure magmatic cones, have been recognized. This study tries to determine if a relationship between the observed volcanic circular structures and participation of water during the eruption exists. Magnetic and gravity field surveys of the circular volcanic structures in Llancanelo and Payunia volcanic fields were performed in order to determine their relationship with the type of eruption. Electromagnetic, magnetic and gravity field surveys were also carried out in Chubut circular structures. The comparative analysis of geological and geophysical results obtained in the circular structures of Chubut and those obtained in the circular structures in the volcanic areas of Llancanelo and Payunia suggest an impact origin for the circular structures of Chubut.

  14. Circular motion of bodies of revolution

    NASA Technical Reports Server (NTRS)

    Kaplan, Carl

    1936-01-01

    The circular motion for airship-like bodies has thus far been calculated only for a prolate ellipsoid of revolution (reference 1, p.133 and reference 2). In this paper, however, the circular motion of elongated bodies of revolution more nearly resembling airships will be investigated. The results will give the effect of rotation on the pressure distribution and thus yield some information as to the stresses set up in an airship in circular flight.

  15. Method of oriented circular dichroism.

    PubMed Central

    Wu, Y; Huang, H W; Olah, G A

    1990-01-01

    We present a new method for determining the orientation of alpha-helical sections of proteins or peptides in membrane. To apply this method, membranes containing proteins must be prepared in a multilayer array. Circular dichroism (CD) spectra of the multilayer sample are then measured at the normal as well as oblique incident angles with respect to the bilayer planes; we call such spectra oriented circular dichroism (OCD). The procedure of OCD measurement, particularly the ways to avoid the spectral artifacts due to the effects of dielectric interfaces, linear dichroism and birefringence, and the method of data analysis are described in detail. To illustrate the method, we analyze the OCD of alamethicin in diphytanoylphosphatidylcholine multilayers. We conclude unambiguously that the helical section of alamethicin is parallel to the membrane normal when the sample is in the full-hydration state, but the helical section rotates to the plane of membrane when the sample is in a low-hydration state. We also obtained the parallel and perpendicular CD spectra of alpha-helix, and found them to be in agreement with previous theoretical calculations based on the exciton theory. These spectra are useful for analyzing protein orientations in future experiments. Images FIGURE 5 PMID:2344464

  16. Circular permutant GFP insertion folding reporters

    DOEpatents

    Waldo, Geoffrey S. (Santa Fe, NM); Cabantous, Stephanie (Los Alamos, NM)

    2008-06-24

    Provided are methods of assaying and improving protein folding using circular permutants of fluorescent proteins, including circular permutants of GFP variants and combinations thereof. The invention further provides various nucleic acid molecules and vectors incorporating such nucleic acid molecules, comprising polynucleotides encoding fluorescent protein circular permutants derived from superfolder GFP, which polynucleotides include an internal cloning site into which a heterologous polynucleotide may be inserted in-frame with the circular permutant coding sequence, and which when expressed are capable of reporting on the degree to which a polypeptide encoded by such an inserted heterologous polynucleotide is correctly folded by correlation with the degree of fluorescence exhibited.

  17. Circular permutant GFP insertion folding reporters

    DOEpatents

    Waldo, Geoffrey S. (Santa Fe, NM); Cabantous, Stephanie (Los Alamos, NM)

    2011-06-14

    Provided are methods of assaying and improving protein folding using circular permutants of fluorescent proteins, including circular permutants of GFP variants and combinations thereof. The invention further provides various nucleic acid molecules and vectors incorporating such nucleic acid molecules, comprising polynucleotides encoding fluorescent protein circular permutants derived from superfolder GFP, which polynucleotides include an internal cloning site into which a heterologous polynucleotide may be inserted in-frame with the circular permutant coding sequence, and which when expressed are capable of reporting on the degree to which a polypeptide encoded by such an inserted heterologous polynucleotide is correctly folded by correlation with the degree of fluorescence exhibited.

  18. Circular permutant GFP insertion folding reporters

    DOEpatents

    Waldo, Geoffrey S.; Cabantous, Stephanie

    2013-04-16

    Provided are methods of assaying and improving protein folding using circular permutants of fluorescent proteins, including circular permutants of GFP variants and combinations thereof. The invention further provides various nucleic acid molecules and vectors incorporating such nucleic acid molecules, comprising polynucleotides encoding fluorescent protein circular permutants derived from superfolder GFP, which polynucleotides include an internal cloning site into which a heterologous polynucleotide may be inserted in-frame with the circular permutant coding sequence, and which when expressed are capable of reporting on the degree to which a polypeptide encoded by such an inserted heterologous polynucleotide is correctly folded by correlation with the degree of fluorescence exhibited.

  19. Circular permutant GFP insertion folding reporters

    DOEpatents

    Waldo, Geoffrey S; Cabantous, Stephanie

    2013-02-12

    Provided are methods of assaying and improving protein folding using circular permutants of fluorescent proteins, including circular permutants of GFP variants and combinations thereof. The invention further provides various nucleic acid molecules and vectors incorporating such nucleic acid molecules, comprising polynucleotides encoding fluorescent protein circular permutants derived from superfolder GFP, which polynucleotides include an internal cloning site into which a heterologous polynucleotide may be inserted in-frame with the circular permutant coding sequence, and which when expressed are capable of reporting on the degree to which a polypeptide encoded by such an inserted heterologous polynucleotide is correctly folded by correlation with the degree of fluorescence exhibited.

  20. 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

    Our Moon is a keystone for understanding the inner solar system impact flux through time, because it is the only body for which we have crater size-frequency distributions (SFDs) through most of bombardment history and radiometric ages of probable associated terrains. Even so, the bombardment rate over the last 3.5 Gyr is poorly understood. According to the spatial density of sub-km craters on dated lunar terrains, the lunar impact flux has been roughly constant over this interval [e.g., 1 and references therein]. If so, one may expect that craters with diameter (D) > 50 km should also be equally dispersed in time over the last 3.5 Gyr. Surprisingly, our new work indicates this may not be so. We have compiled SFDs for small, superposed craters with D~0.6-15 km on the original floors of several previously designated Copernican and Eratothenian craters (USGS Geological Atlas of the Moon and [2]) with D > 50 km using JMARS. Using these data we compute the large craters' formation model ages with the Model Production Function chronology developed by Marchi et al. [3]. Many of these craters, especially on the farside (e.g., Sharnov, Birkeland), can now be suitably examined only because of the excellent LROC imaging (we use the Wide Angle Camera mosaic). As a test of our methods, we calculated the model age of the 55 km crater Aristillus (34°N, 1°E), a relatively young crater thought to have showered the Apollo 15 landing site with ejecta. Interestingly, our model age of 2.2 ± 0.6 Ga is surprisingly consistent with a 2.1 Ga-old impact-derived clast (radiometric age) returned by the Apollo 15 astronauts [4]. We find that nearly all of our computed ages for the large craters are older than indicated by previous work, with very few having ages younger than 3 Ga. Reasons for these discrepancies include (i) use of poor resolution Lunar Orbiter images (especially away from the near side) and (ii) application of the unreliable "DL" method, which involves simplified 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.

  1. The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. XI. Lupus Observed With IRAC and MIPS

    E-print Network

    Bruno Merin; Jes Jorgensen; Loredana Spezzi; Juan M. Alcala; Neal J. Evans II; Paul M. Harvey; Nicholas Chapman; Tracy Huard; Ewine F. van Dishoeck; Fernando Comeron

    2008-03-10

    We present c2d Spitzer/IRAC observations of the Lupus I, III and IV dark clouds and discuss them in combination with optical and near-infrared and c2d MIPS data. With the Spitzer data, the new sample contains 159 stars, 4 times larger than the previous one. It is dominated by low- and very-low mass stars and it is complete down to M $\\approx$ 0.1M$_\\odot$. We find 30-40 % binaries with separations between 100 to 2000 AU with no apparent effect in the disk properties of the members. A large majority of the objects are Class II or Class III objects, with only 20 (12%) of Class I or Flat spectrum sources. The disk sample is complete down to ``debris''-like systems in stars as small as M $\\approx$ 0.2 M$_\\odot$ and includes sub-stellar objects with larger IR excesses. The disk fraction in Lupus is 70 -- 80%, consistent with an age of 1 -- 2 Myr. However, the young population contains 20% optically thick accretion disks and 40% relatively less flared disks. A growing variety of inner disk structures is found for larger inner disk clearings for equal disk masses. Lupus III is the most centrally populated and rich, followed by Lupus I with a filamentary structure and by Lupus IV, where a very high density core with little star-formation activity has been found. We estimate star formation rates in Lupus of 2 -- 10 M$_\\odot$ Myr$^{-1}$ and star formation efficiencies of a few percent, apparently correlated with the associated cloud masses.

  2. Progress on LES of Flow Past a Circular Cylinder

    NASA Technical Reports Server (NTRS)

    Mittal, R.

    1996-01-01

    The objective of the present research is to assess the usefulness of large-eddy simulation (LES) methodology for flows in complex geometries. Flow past a circular cylinder has been calculated using a central-difference based solver, and the results have been compared to those obtained by a solver that employs higher-order upwind biased schemes (Beaudan & Moin, 1994). This comparison allows us to assess the suitability of these schemes for LES in complex geometry flows.

  3. Linear dichroism and circular dichroism in photosynthesis research

    Microsoft Academic Search

    Gy?z? Garab; Herbert van Amerongen

    2009-01-01

    The efficiency of photosynthetic light energy conversion depends largely on the molecular architecture of the photosynthetic\\u000a membranes. Linear- and circular-dichroism (LD and CD) studies have contributed significantly to our knowledge of the molecular\\u000a organization of pigment systems at different levels of complexity, in pigment–protein complexes, supercomplexes, and their\\u000a macroassemblies, as well as in entire membranes and membrane systems. Many examples

  4. A Circular Statistical Method for Extracting Rotation Measures

    E-print Network

    S. Sarala; Pankaj Jain

    2000-07-18

    We propose a new method for the extraction of Rotation Measure from spectral polarization data. The method is based on maximum likelihood analysis and takes into account the circular nature of the polarization data. The method is unbiased and statistically more efficient than the standard $\\chi^2$ procedure. We also find that the method is computationally much faster than the standard $\\chi^2$ procedure if the number of data points are very large.

  5. Rain Characteristics and Large-Scale Environments of Precipitation Objects with Extreme Rain Volumes from TRMM Observations

    NASA Technical Reports Server (NTRS)

    Zhou, Yaping; Lau, William K M.; Liu, Chuntao

    2013-01-01

    This study adopts a "precipitation object" approach by using 14 years of Tropical Rainfall Measuring Mission (TRMM) Precipitation Feature (PF) and National Centers for Environmental Prediction (NCEP) reanalysis data to study rainfall structure and environmental factors associated with extreme heavy rain events. Characteristics of instantaneous extreme volumetric PFs are examined and compared to those of intermediate and small systems. It is found that instantaneous PFs exhibit a much wider scale range compared to the daily gridded precipitation accumulation range. The top 1% of the rainiest PFs contribute over 55% of total rainfall and have 2 orders of rain volume magnitude greater than those of the median PFs. We find a threshold near the top 10% beyond which the PFs grow exponentially into larger, deeper, and colder rain systems. NCEP reanalyses show that midlevel relative humidity and total precipitable water increase steadily with increasingly larger PFs, along with a rapid increase of 500 hPa upward vertical velocity beyond the top 10%. This provides the necessary moisture convergence to amplify and sustain the extreme events. The rapid increase in vertical motion is associated with the release of convective available potential energy (CAPE) in mature systems, as is evident in the increase in CAPE of PFs up to 10% and the subsequent dropoff. The study illustrates distinct stages in the development of an extreme rainfall event including: (1) a systematic buildup in large-scale temperature and moisture, (2) a rapid change in rain structure, (3) explosive growth of the PF size, and (4) a release of CAPE before the demise of the event. XXXX This study adopts a "precipitation object" approach by using the Precipitation Feature (PF) database developed at the University of Utah to analyze the characteristics and large-scale environment of extreme precipitation from 14 year TRMM observations. We define extreme PF with the volumetric rain of the PF in order to capture the effect of both spatial extent and rain intensity. We have found that instantaneous PFs have much larger dynamic ranges than the daily gridded precipitation, with those in the top 1% being 2 orders of magnitude larger than the medium PFs and contributing to over 55% of instantaneous rainfall. Ninety percent of the PFs that contribute about 20% of total precipitation belong to meso-? systems (less than 20 km in the horizontal direction) or broken patches from large systems. The most abrupt change is found to be around the top 10%-1%, where the rain systems expand from a few hundred to a few thousand kilometers in size and from 2300 to 40,000 mm/h km2 in rain volume. Spatial and temporal distributions and the mean characteristics of extreme PFs are discussed in comparison to intermediate and smaller PFs. We find that regional differences in rain characteristics mainly come from land-ocean differences for smaller PFs. As the VRR of PF increases, the regional differences mainly come from the tropics and subtropics. While extreme PFs in the top 1% are found to be significantly larger, deeper, and colder than the lower 90% of PFs, extreme PFs in the tropics are even deeper and colder than the subtropical systems and present no significant seasonal variations. The extreme PFs in the subtropics in the summertime resemble those in the tropics, characterized by locally convection-driven rain systems. The extreme PFs in subtropical winter are much broader and shallower, which reanalysis shows that midlevel relative humidity and total precipitable water increase consistently with increasingly larger rain systems, along with sharp increases of upward vertical velocities to provide necessary dynamic support. Instantaneous CAPE also generally increases with larger PF, but the mean CAPE levels off for the extremely large systems due to the release of CAPE in mature systems in subtropical land regions. The study illustrates important roles of large-scale moisture and dynamic conditions for occurrences of extreme precipitation. [40] It has been widely acce

  6. Circular domain features based condition monitoring for low speed slewing bearing

    NASA Astrophysics Data System (ADS)

    Caesarendra, Wahyu; Kosasih, Buyung; Tieu, Anh Kiet; Moodie, Craig A. S.

    2014-03-01

    This paper presents a novel application of circular domain features calculation based condition monitoring method for low rotational speed slewing bearing. The method employs data reduction process using piecewise aggregate approximation (PAA) to detect frequency alteration in the bearing signal when the fault occurs. From the processed data, circular domain features such as circular mean, circular variance, circular skewness and circular kurtosis are calculated and monitored. It is shown that the slight changes of bearing condition during operation can be identified more clearly in circular domain analysis compared to time domain analysis and other advanced signal processing methods such as wavelet decomposition and empirical mode decomposition (EMD) allowing the engineer to better schedule the maintenance work. Four circular domain features were shown to consistently and clearly identify the onset (initiation) of fault from the peak feature value which is not clearly observable in time domain features. The application of the method is demonstrated with simulated data, laboratory slewing bearing data and industrial bearing data from Coal Bridge Reclaimer used in a local steel mill.

  7. Detection of biological particles by the use of circular dichroism measurements improved by scattering theory

    NASA Astrophysics Data System (ADS)

    Rosen, David L.; Pendleton, J. David

    1995-09-01

    Light scattered from optically active spheres was theoretically analyzed for biodetection. The circularly polarized signal of near-forward scattering from circularly dichroic spheres was calculated. Both remote and point biodetection were considered. The analysis included the effect of a circular aperture and beam block at the detector. If the incident light is linearly polarized, a false signal would limit the sensitivity of the biodetector. If the incident light is randomly polarized, shot noise would limit the sensitivity. Suggested improvements to current techniques include a beam block, precise angular measurements, randomly polarized light, index-matching fluid, and larger apertures for large particles.

  8. Detection of biological particles by the use of circular dichroism measurements improved by scattering theory.

    PubMed

    Rosen, D L; Pendleton, J D

    1995-09-01

    Light scattered from optically active spheres was theoretically analyzed for biodetection. The circularly polarized signal of near-forward scattering from circularly dichroic spheres was calculated. Both remote and point biodetection were considered. The analysis included the effect of a circular aperture and beam block at the detector. If the incident light is linearly polarized, a false signal would limit the sensitivity of the biodetector. If the incident light is randomly polarized, shot noise would limit the sensitivity. Suggested improvements to current techniques include a beam block, precise angular measurements, randomly polarized light, index-matching fluid, and larger apertures for large particles. PMID:21060423

  9. Robust fault diagnosis for a satellite large angle attitude system using an iterative neuron PID (INPID) observer

    Microsoft Academic Search

    Qing Wu; Mehrdad Saif

    2006-01-01

    A fault detection and diagnosis (FDD) scheme using an iterative neuron PID (INPID) observer is explored in this paper. The observer input, which is used to estimate state faults, is computed by utilizing the proportional, integral, and derivative information of the fault estimation error. Two classes of robust adaptive algorithms are adopted to update the parameters of the observer input.

  10. Comparison of the Single Molecule Dynamics of Linear and Circular DNAs in Planar Extensional Flows

    NASA Astrophysics Data System (ADS)

    Li, Yanfei; Hsiao, Kai-Wen; Brockman, Christopher; Yates, Daniel; McKenna, Gregory; Schroeder, Charles; San Francisco, Michael; Kornfield, Julie; Anderson, Rae

    2015-03-01

    Chain topology has a profound impact on the flow behaviors of single macromolecules. The absence of free ends separates circular polymers from other chain architectures, i.e., linear, star, and branched. In the present work, we study the single chain dynamics of large circular and linear DNA molecules by comparing the relaxation dynamics, steady state coil-stretch transition, and transient molecular individualism behaviors for the two types of macromolecules. To this end, large circular DNA molecules were biologically synthesized and studied in a microfluidic device that has a cross-slot geometry to develop a stagnation point extensional flow. Although the relaxation time of rings scales in the same way as for the linear analog, the circular polymers show quantitatively different behaviors in the steady state extension and qualitatively different behaviors during a transient stretch. The existence of some commonality between these two topologies is proposed. Texas Tech University John R. Bradford Endowment.

  11. Nonlinear bending and post-buckling of a functionally graded circular plate under mechanical and thermal loadings

    Microsoft Academic Search

    L. S. Ma; T. J. Wang

    2003-01-01

    Based on the classical nonlinear von Karman plate theory, axisymmetric large deflection bending of a functionally graded circular plate is investigated under mechanical, thermal and combined thermal–mechanical loadings, respectively, and axisymmetric thermal post-buckling behavior of a functionally graded circular plate is also investigated. The mechanical and thermal properties of functionally graded material (FGM) are assumed to vary continuously through the

  12. Flow feature of a pair of in-line forced oscillating 45 degrees staggered arranged circular cylinders

    NASA Astrophysics Data System (ADS)

    Yokoi, Y.; Hirao, K.

    2015-05-01

    In order to understand the aspect of the mutual interference flow from two circular cylinders, the visual observation experiments was performed. The staggered arrangement angle was made into 45 degrees and the cylinder setting conditions were three kinds of distance ratios (L/d = 1.5, 2.5 and 5.5). The oscillating conditions were four kinds of amplitude ratios (2a/d = 0.25, 0.5, 0.75 and 1.0), and the oscillation frequency ratio f/fK in 28 steps. The Reynolds number was about 640. As the result of experiment, also in the case of staggered arrangement oscillating two circular cylinders, the lock-in phenomenon was observed. Four characteristic flow patterns at the time of lock-in were obtained by having oscillated two circular cylinders of staggered arrangement in the direction of the flow. Even if the mutual interference of two circular cylinders was in the state of appearing strongly, when the circular cylinder was oscillated, the lock-in phenomenon was observed. In a single circular cylinder and two circular cylinders of staggered arrangement, the distribution of the range and a flow pattern which carries out a lock-in differs. Distribution of the flow pattern of the 1st circular cylinder and distribution of the flow pattern of the 2nd circular cylinder change with distance ratios.

  13. OBSERVATIONS OF THE NEAR- TO MID-INFRARED UNIDENTIFIED EMISSION BANDS IN THE INTERSTELLAR MEDIUM OF THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Mori, Tamami I.; Sakon, Itsuki; Onaka, Takashi; Ohsawa, Ryou [Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Kaneda, Hidehiro [Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602 (Japan); Umehata, Hideki, E-mail: morii@astron.s.u-tokyo.ac.jp, E-mail: isakon@astron.s.u-tokyo.ac.jp, E-mail: onaka@astron.s.u-tokyo.ac.jp [Institute of Astronomy, Graduate School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)

    2012-01-01

    We present the results of near- to mid-infrared slit spectroscopic observations (2.55-13.4 {mu}m) of the diffuse emission toward nine positions in the Large Magellanic Cloud with the infrared camera on board AKARI. The target positions are selected to cover a wide range of the intensity of the incident radiation field. The unidentified infrared bands at 3.3, 6.2, 7.7, 8.6, and 11.3 {mu}m are detected toward all the targets and ionized gas signatures; hydrogen recombination lines and ionic forbidden lines are detected toward three of them. We classify the targets into two groups: those without the ionized gas signatures (Group A) and those with the ionized signatures (Group B). Group A includes molecular clouds and photodissociation regions, whereas Group B consists of H II regions. In Group A, the band ratios of I{sub 3.3{mu}m}/I{sub 11.3{mu}m}, I{sub 6.2{mu}m}/I{sub 11.3{mu}m}, I{sub 7.7{mu}m}/I{sub 11.3{mu}m}, and I{sub 8.6{mu}m}/I{sub 11.3{mu}m} show positive correlation with the IRAS and AKARI colors, but those of Group B do not follow the correlation. We discuss the results in terms of the polycyclic aromatic hydrocarbon (PAH) model and attribute the difference to the destruction of small PAHs and an increase in the recombination due to the high electron density in Group B. In the present study, the 3.3 {mu}m band provides crucial information on the size distribution and/or the excitation conditions of PAHs and plays a key role in the distinction of Group A from B. The results suggest the possibility of the diagram of I{sub 3.3{mu}m}/I{sub 11.3{mu}m} versus I{sub 7.7{mu}m}/I{sub 11.3{mu}m} as an efficient diagnostic tool to infer the physical conditions of the interstellar medium.

  14. Long-term Observations of Ecohydrology, Climate, Energy Fluxes, and Eddy Covariance Error in a Large, Semiarid Floodplain

    NASA Astrophysics Data System (ADS)

    Cleverly, J. R.; Thibault, J. R.; Dahm, C. N.; Allred Coonrod, J. E.; Slusher, M.; Teet, S.; Schuetz, J.

    2008-12-01

    Some of the highest rates of water and energy fluxes between terrestrial ecosystems and the atmosphere occur over large floodplains in arid and semiarid areas. Often located in high-pressure zones near 35 degrees latitude, abundant radiation and easily accessible groundwater contribute few limitations on growth and production in desert phreatophytes. Desert regions typically undergo cycles of drought and floods, and phreatophytic communities wax or wane in cover, density, and structure with cumulative species responses to timing and severity in these regional weather cycles. The Rio-ET Laboratory at the University of New Mexico has been collecting long-term data from a flux network of riparian monitoring stations, mounted on towers along the Middle Rio Grande. Ongoing measurements of energy, water and carbon dioxide fluxes, groundwater dynamics, meteorology, leaf area index, and community dynamics began at some locations in 1999. Recent reanalysis of the flux dataset was performed in which error correction procedures were compared to each and other and in relation to an irrigated crop under advection. Most riparian sites exhibited stable atmospheric stratification and an energy balance consistent with evaporative cooling. Evaporative cooling was more prominent in the late afternoon and evening, during wet conditions. Reduced latent heat fluxes were observed in a cottonwood forest following restoration and fire, but only in years when the forest floor was not re-vegetated by opportunistic annuals or target removal species. Water use by riparian phreatophytes was 1) non-responsive to drought during the monsoon season (non-native Russian olive and monospecific saltcedar communities), 2) responded negatively to monsoon-season drought (xeroriparian saltcedar and saltgrass mosaic community), or 3) responded positively to monsoon-season drought (cottonwood forests). Water salvage related to ecological restoration is dependent upon restoration strategy, emphasizing the importance of due diligent followup to prevent unintentional re-vegetation of the site. Restoration of monospecific saltcedar provides the greatest opportunity for water salvage although restoration of cottonwood forests through removal of densely-packed non-native understory results in marginal water salvage. Benefits of ecosystem restoration increase with drought and during the period of explosive growth following a period of prolonged drought.

  15. Some radar observations of meteors and aurorae at 300 and 500 Mc\\/s using a large radio telescope--II Observations of the aurora borealis

    Microsoft Academic Search

    D. Barber; H. K. Sutcliffe; C. D. Watkins

    1962-01-01

    Radar echoes from the aurora borealis have been obtained at frequencies of 300 and 500 Mc\\/s using a 250 ft radio telescope. Strong echoes detected during the afternoon hours originated from a layer of ionization at a mean height of 110 km and less than a few kilometres thick. Isolated weak echoes observed at other times originated from localized regions

  16. Diagnostic of stellar magnetic fields with cumulative circular polarisation profiles

    E-print Network

    Kochukhov, O

    2015-01-01

    Information about stellar magnetic field topologies is obtained primarily from high-resolution circular polarisation (Stokes $V$) observations. Due to their generally complex morphologies, the stellar Stokes $V$ profiles are usually interpreted with elaborate inversion techniques such as Zeeman Doppler imaging (ZDI). Here we further develop a new method of interpretation of circular polarisation signatures in spectral lines using cumulative Stokes $V$ profiles (anti-derivative of Stokes $V$). This method is complimentary to ZDI and can be applied for validation of the inversion results or when the available observational data are insufficient for an inversion. Based on the rigorous treatment of polarised line formation in the weak-field regime, we show that, for rapidly rotating stars, the cumulative Stokes $V$ profiles contain information about the spatially resolved longitudinal magnetic field density. Rotational modulation of these profiles can be employed for a simple, qualitative characterisation of the ...

  17. Circular Holonomy and Clock Effects in Stationary Axisymmetric Spacetimes

    E-print Network

    Donato Bini; Robert T. Jantzen; Bahram Mashhoon

    2001-11-09

    Stationary axisymmetric spacetimes containing a pair of oppositely-rotating periodically-intersecting circular geodesics allow the study of various so-called `clock effects' by comparing either observer or geodesic proper time periods of orbital circuits defined by the observer or the geodesic crossing points. This can be extended from a comparison of clocks to a comparison of parallel transported vectors, leading to the study of special elements of the spacetime holonomy group. The band of holonomy invariance found for a dense subset of special geodesic orbits outside a certain radius in the static case does not exist in the nonstatic case. In the Kerr spacetime the dimensionless frequencies associated with parallel transport rotations can be expressed as ratios of the proper and average coordinate periods of the circular geodesics.

  18. Circular dichroism from single plasmonic nanostructures with extrinsic chirality

    NASA Astrophysics Data System (ADS)

    Lu, Xuxing; Wu, Jian; Zhu, Qiannan; Zhao, Junwei; Wang, Qiangbin; Zhan, Li; Ni, Weihai

    2014-11-01

    Circular dichroism (CD) studies on single nanostructures can yield novel insights into chiroptical physics that are not available from traditional ensemble-based measurements, yet they are challenging because of their weak signals. By introducing an oblique excitation beam, we demonstrate the observation and spectroscopic analysis of a prominent plasmonic chiroptical response from a single v-shaped gold nanorod dimer nanostructure. We show that circular differential scattering from the obliquely excited gold nanorod dimer yields a characteristic bisignate peak-dip spectral shape at hybridized energies of the dimer. This chiroptical response can be ascribed to extrinsic chirality which depends on the geometry configurations of the chiral arrangement. Due to strong near-field coupling, the dipole orientations of the hybridized resonance modes can be in favor of the incident circularly polarized light where a maximum g-factor of ~0.4 is observed. Promising applications of this chiroptical arrangement as a key component can be in electronics, photonics, or metamaterials.Circular dichroism (CD) studies on single nanostructures can yield novel insights into chiroptical physics that are not available from traditional ensemble-based measurements, yet they are challenging because of their weak signals. By introducing an oblique excitation beam, we demonstrate the observation and spectroscopic analysis of a prominent plasmonic chiroptical response from a single v-shaped gold nanorod dimer nanostructure. We show that circular differential scattering from the obliquely excited gold nanorod dimer yields a characteristic bisignate peak-dip spectral shape at hybridized energies of the dimer. This chiroptical response can be ascribed to extrinsic chirality which depends on the geometry configurations of the chiral arrangement. Due to strong near-field coupling, the dipole orientations of the hybridized resonance modes can be in favor of the incident circularly polarized light where a maximum g-factor of ~0.4 is observed. Promising applications of this chiroptical arrangement as a key component can be in electronics, photonics, or metamaterials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04433a

  19. Arctic-HYCOS: a Large Sample observing system for estimating freshwater fluxes in the drainage basin of the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Pietroniro, Al; Korhonen, Johanna; Looser, Ulrich; Hardardóttir, Jórunn; Johnsrud, Morten; Vuglinsky, Valery; Gustafsson, David; Lins, Harry F.; Conaway, Jeffrey S.; Lammers, Richard; Stewart, Bruce; Abrate, Tommaso; Pilon, Paul; Sighomnou, Daniel; Arheimer, Berit

    2015-04-01

    The Arctic region is an important regulating component of the global climate system, and is also experiencing a considerable change during recent decades. More than 10% of world's river-runoff flows to the Arctic Ocean and there is evidence of changes in its fresh-water balance. However, about 30% of the Arctic basin is still ungauged, with differing monitoring practices and data availability from the countries in the region. A consistent system for monitoring and sharing of hydrological information throughout the Arctic region is thus of highest interest for further studies and monitoring of the freshwater flux to the Arctic Ocean. The purpose of the Arctic-HYCOS project is to allow for collection and sharing of hydrological data. Preliminary 616 stations were identified with long-term daily discharge data available, and around 250 of these already provide online available data in near real time. This large sample will be used in the following scientific analysis: 1) to evaluate freshwater flux to the Arctic Ocean and Seas, 2) to monitor changes and enhance understanding of the hydrological regime and 3) to estimate flows in ungauged regions and develop models for enhanced hydrological prediction in the Arctic region. The project is intended as a component of the WMO (World Meteorological Organization) WHYCOS (World Hydrological Cycle Observing System) initiative, covering the area of the expansive transnational Arctic basin with participation from Canada, Denmark, Finland, Iceland, Norway, Russian Federation, Sweden and United States of America. The overall objective is to regularly collect, manage and share high quality data from a defined basic network of hydrological stations in the Arctic basin. The project focus on collecting data on discharge and possibly sediment transport and temperature. Data should be provisional in near-real time if available, whereas time-series of historical data should be provided once quality assurance has been completed. The initial stages of the project will focus on collecting data on discharge and revise station selection criteria. For monitoring freshwater flow to oceans, stations close to the mouths of rivers and immediately inland for back-up purposes will be preferred. For studies of change emphasis is placed on hydrological regime stations located in headwaters small sub-catchments, including pristine basins. Stations outside the Arctic Ocean basin, such as at the mouth of the Yukon River, Baltic Sea and Hudson Bay, can also be considered to allow a better understanding of hydrological processes occurring in the general region. Countries shall facilitate, to the extent possible, access to their data currently published online, and also access to those not yet regularly published on the web. At a later stage data exchange standards such as WaterML2.0 will be implemented. The project will also perform pan-Arctic hydrological modelling (geo-statistical, deterministic and probabilistic methods) for the assessment and integration of observational and modelled data to improve estimates of ungauged discharge and the overall estimates of freshwater flux to the Arctic Ocean, as well as understanding of hydrological processes.

  20. Properties of Bulgeless Disk Galaxies. II. Star Formation as a Function of Circular Velocity

    NASA Astrophysics Data System (ADS)

    Watson, Linda C.; Martini, Paul; Lisenfeld, Ute; Wong, Man-Hong; Böker, Torsten; Schinnerer, Eva

    2012-06-01

    We study the relation between the surface density of gas and star formation rate in 20 moderately inclined, bulgeless disk galaxies (Sd-Sdm Hubble types) using CO(1-0) data from the IRAM 30 m telescope, H I emission line data from the VLA/EVLA, H? data from the MDM Observatory, and polycyclic aromatic hydrocarbon emission data derived from Spitzer IRAC observations. We specifically investigate the efficiency of star formation as a function of circular velocity (v circ). Previous work found that the vertical dust structure and disk stability of edge-on, bulgeless disk galaxies transition from diffuse dust lanes with large scale heights and gravitationally stable disks at v circ < 120 km s-1 (M * <~ 1010 M ?) to narrow dust lanes with small scale heights and gravitationally unstable disks at v circ > 120 km s-1. We find no transition in star formation efficiency (\\Sigma _SFR/\\Sigma _H\\,\\mathsc{i+H_{2}}) at v circ = 120 km s-1 or at any other circular velocity probed by our sample (v circ = 46-190 km s-1). Contrary to previous work, we find no transition in disk stability at any circular velocity in our sample. Assuming our sample has the same dust structure transition as the edge-on sample, our results demonstrate that scale height differences in the cold interstellar medium of bulgeless disk galaxies do not significantly affect the molecular fraction or star formation efficiency. This may indicate that star formation is primarily affected by physical processes that act on smaller scales than the dust scale height, which lends support to local star formation models.

  1. Iterative reconstruction for circular cone-beam CT with an offset flat-panel detector

    Microsoft Academic Search

    Eberhard Hansis; Jorg Bredno; David Sowards-Emmerd; Lingxiong Shao

    2010-01-01

    Circular cone-beam computed tomography (CBCT) with a tangentially offset flat-panel X-ray detector offers a large CT field-of-view (FoV) with a relatively small detector. It is used in practice, e.g., for target imaging in image-guided radiotherapy or for localization and attenuation correction in SPECT\\/CT imaging. The X-ray projections, acquired on a circular source trajectory, each cover roughly half the CT FoV;

  2. Cost Allocation Policy OMB Circular A-21

    E-print Network

    Clark, John

    Expenses can be allocated to the federal grant or contract activity based on benefit derived, causeCost Allocation Policy OMB Circular A-21 Office of Management and Budget (OMB) Circular A-21 establishes principles for determining costs applicable to grants, contracts, and other agreements

  3. Broadband circular polarizers using plasmonic metasurfaces

    Microsoft Academic Search

    Yang Zhao; Andrea Alu

    2011-01-01

    In nature, circular polarization detection is unique to bio-systems, since human eyes cannot detect polarization information. Various animal species successfully use it for defense, signaling and orientation. It may be of great interest to reproduce these functionalities in artificial photonic devices, being able to distinguish different handedness of circular polarization, and to possibly integrate this operation with other photonic systems.

  4. A Random Walk on a Circular Path

    ERIC Educational Resources Information Center

    Ching, W.-K.; Lee, M. S.

    2005-01-01

    This short note introduces an interesting random walk on a circular path with cards of numbers. By using high school probability theory, it is proved that under some assumptions on the number of cards, the probability that a walker will return to a fixed position will tend to one as the length of the circular path tends to infinity.

  5. Visualization techniques for circular tabletop interfaces

    Microsoft Academic Search

    Frédéric Vernier; Neal Lesh; Chia Shen

    2002-01-01

    This paper presents visualization and layout schemes developed for a novel circular user interface designed for a round, tabletop display. Since all the displayed items are in a polar coordinate system, many interface and visualization schemes must be revisited to account for this new layout of UI elements. We discuss the direct implications of such a circular interface on document

  6. Research on Green Packaging of Circular Economy

    Microsoft Academic Search

    Zhang Guirong; Li Dehua; Wang Zhiping; Ma Chenglin

    2010-01-01

    The circular economy is the resource recycling economy, is the economy of harmonious development between economy and environment, also a kind of ecological economy. Circular economy demands that enterprises' logistics activities be green logistics packaging. The green packaging aims at improving the packing materials reuse, reducing resource consumption and lowering packaging waste pollution to the environment. Implementing green logistics packaging,

  7. Ligand Induced Circular Dichroism and Circularly Polarized Luminescence in CdSe Quantum Dots

    PubMed Central

    Tohgha, Urice; Deol, Kirandeep K.; Porter, Ashlin G.; Bartko, Samuel G.; Choi, Jung Kyu; Leonard, Brian M.; Varga, Krisztina; Kubelka, Jan; Muller, Gilles; Balaz, Milan

    2014-01-01

    Chiral thiol capping ligands L- and D-cysteines induced modular chiroptical properties in achiral cadmium selenide quantum dots (CdSe QDs). Cys-CdSe prepared from achiral oleic acid capped CdSe by post-synthetic ligand exchange displayed size-dependent electronic circular dichroism (CD) and circularly polarized luminescence (CPL). Opposite CPL signals were measured for the CdSe QDs capped with D- and L-cysteine. The CD profile and CD anisotropy varied with size of CdSe nanocrystals with largest anisotropy observed for CdSe nanoparticles of 4.4 nm. Magic angle spinning solid state NMR (MAS ssNMR) experiments suggested bidentate interaction between cysteine and the surface of CdSe. Density functional theory (DFT) calculations verified that attachment of L- and D-cysteine to the surface of model (CdSe)13 nanoclusters induces measurable opposite CD signals for the exitonic band of the nanocluster. The chirality was induced by the hybridization of highest occupied CdSe molecular orbitals with those of the chiral ligand. PMID:24200288

  8. Biological Sensing with Terahertz Circular Dichroism Spectroscopy

    NASA Astrophysics Data System (ADS)

    Xu, J.; Ramian, G.; Scopatz, A. M.; Allen, S. J.; Plaxco, K. W.

    2003-03-01

    Chirality is believed to be a general and unique trait of life. Since biopolymers absorb broadly in the terahertz regime, we expect circular dichroism to appear everywhere but with zero-crossings as a bio-polymer specific spectroscopic signature; terahertz circular dichroism (heretofore unexplored) may provide a universal and unambiguous signature of biological systems, regardless of their genesis. We are building a novel terahertz circular dichroism spectrometer. It is being tested with a 139 gigahertz Gunn source. But, we will explore terahertz circular dichroism over a very broad frequency range, in and out of aqueous solution using the intense and broadly tunable terahertz radiation from the free electron lasers at UCSB (0.12 to 4.75 THz). Preliminary experimental results will be presented as well as coupled harmonic oscillator models for the broad terahertz frequency circular dichroism expected for these disordered systems. Supported by NASA abd ARO

  9. The circular Bragg phenomenon for oblique incidence

    NASA Astrophysics Data System (ADS)

    Erten, Sema; Lakhtakia, Akhlesh; Barber, Greg D.

    2015-02-01

    Structurally chiral materials exhibit the circular Bragg phenomenon (CBP). These materials preferentially reflect circularly polarized light of the same handedness while transmitting circularly polarized light of the opposite handedness within a range of wavelengths called the circular Bragg regime. The CBP has been extensively investigated experimentally for normal incidence, but not for oblique incidence. After fabricating a 20-periodthick chiral sculptured thin film, we measured all of its circular remittances over a 60° range of the angle of incidence and a 300-nm range of the free-space wavelength. Provided the incidence is not very oblique, the obtained dependencies of the center wavelength and the bandwidth of the CBP on the angle of incidence match theoretical estimates.

  10. Gauss-Bonnet correction to holographic thermalization: Two-point functions, circular Wilson loops, and entanglement entropy

    NASA Astrophysics Data System (ADS)

    Li, Yong-Zhuang; Wu, Shao-Feng; Yang, Guo-Hong

    2013-10-01

    We study the thermalization of a class of four-dimensional strongly coupled theories dual to a five-dimensional AdS-Vaidya spacetime with Gauss-Bonnet curvature corrections. We probe the thermalization using the two-point functions, the expectation values of circular Wilson loops, and entanglement entropy. When boundary separation is small, we observe that the thermalization times of these observables have weak dependence on the Gauss-Bonnet coupling constant ?. In addition, the growth rate of entanglement entropy density is nearly volume independent. We also show that a new kind of swallowtail behavior may appear in the thermalization of the two-point function when ? is negative and ? is large enough. At large negative ? (??-0.1) the relationship between the critical thermalization time of entanglement entropy and the boundary separation encounters a certain “phase transition.”

  11. Evaluating the Reliability of Reanalysis as a Substitute for Observational Data in Large-scale Agricultural Assessments

    NASA Astrophysics Data System (ADS)

    Glotter, M.; Ruane, A. C.; Moyer, E. J.; Elliott, J. W.

    2014-12-01

    Future projections of food security require historical agricultural assessments to validate, improve, and understand the limitations of yield estimates. Poor observational climate networks often force historical assessments to rely on reanalysis data- climate model output nudged by observations- for inputs to crop models. However, agricultural yields are sensitive to changes in precipitation, and since reanalysis products generally use little or no observational precipitation in the data assimilation process, its use may compromise the validation exercise. Previous studies do not systematically assess whether reanalysis data is sufficient or data measurements are required. We test the reliability of reanalysis data for agricultural analyses with simulations of maize yields in the U.S., where observational data are extensive. We drive the widely used Decision Support System for Agrotechnology Transfer (DSSAT) crop model with climate inputs from a combination of data sources: bias- and unbias-corrected reanalyses, and observation-based precipitation and solar radiation. We find that driving DSSAT with reanalysis precipitation produces unreliable yield estimates, but driving it with reanalysis bias-corrected with monthly observations is more robust. Bias corrections do require observational data, but gathering reliable monthly data may be easier than gathering daily data. The approach is therefore promising for data-poor regions where observational precipitation is less available and existing data is unreliable. The priority for climate monitoring networks may not be in daily records but instead in lower-cost observational systems that estimate data over coarser temporal resolutions.

  12. Experimental observation of isolated large transverse energy electrons with associated missing energy at sqrt(s)=540 GeV

    Microsoft Academic Search

    Geoffrey T J Arnison; Alan Astbury; Bernard Aubert; Cesare Bacci; G. Bauer; A. Bézaguet; R. Böck; T. J. V. Bowcock; M. Calvetti; T. Carroll; P. Catz; P. Cennini; S. Centro; F. Ceradini; S. Cittolin; D. Cline; C. Cochet; J. Colas; M. Corden; D. Dallman; M. Debeer; M. della Negra; M. Demoulin; D. Denegri; A. di Ciaccio; D. Dibitonto; L. Dobrzynski; J. D. Dowell; M. Edwards; K. Eggert; E. Eisenhandler; N. Ellis; P. Erhard; H. Faissner; G. Fontaine; R. Frey; R. Frühwirth; J. Garvey; S. Geer; C. Ghesquière; P. Ghez; K. L. Giboni; W. R. Gibson; Y. Giraud-Héraud; A. Givernaud; A. Gonidec; G. Grayer; P. Gutierrez; T. Hansl-Kozanecka; W. J. Haynes; L. O. Hertzberger; C. Hodges; D. Hoffmann; H. Hoffmann; D. J. Holthuizen; R. J. Homer; A. Honma; W. Jank; G. Jorat; P. I. P. Kalmus; V. Karimäki; R. Keeler; I. Kenyon; A. Kernan; R. Kinnunen; H. Kowalski; W. Kozanecki; D. Kryn; F. Lacava; J.-P. Laugier; J P Laugier; H. Lehmann; K. Leuchs; A. Lévêque; E. Linglin; E. Locci; M. Loret; J.-J. Malosse; T. Markiewicz; G. Maurin; T. McMahon; J.-P. Mendiburu; M.-N. Minard; M. Moricca; H. Muirhead; F. Muller; A. K. Nandi; L. Naumann; A. Norton; A. Orkin-Lecourtois; L. Paoluzi; G. Petrucci; G. Piano Mortari; M. Pimiä; A. Placci; E. Radermacher; J. Ransdell; H. Reithler; J.-P. Revol; J. Rich; M. Rijssenbeek; C. Roberts; J. Rohlf; P. Rossi; Carlo Rubbia; Bernard Sadoulet; G. Sajot; G. Salvi; J. Salvini; Jean Sass; A. Saudraix; Aurore Savoy-Navarro; D. Schinzel; W. Scott; T. P. Shah; Michel Spiro; J. Strauss; K. Sumorok; F. Szoncso; D. Smith; Charling Tao; G. Thompson; J. Timmer; E. Tscheslog; Jorma Tuominiemi; S. van der Meer; J.-P. Vialle; J. Vrana; V. Vuillemin; H. D. Wahl; P M Watkins; J. Wilson; Y. G. Xie; Michel Jean Paul Yvert; Erwin Zurfluh

    1983-01-01

    We report the results of two searches made on data recorded at the CERN SPS Proton-Antiproton Collider: one for isolated large-ET electrons, the other for large-ET neutrinos using the technique of missing transverse energy. Both searches converge to the same events, which have the signature of a two-body decay of a particle of mass ~80 GeV\\/c2. The topology as well

  13. X6.9-class Flare Induced Vertical Kink Oscillations in a Large-Scale Plasma Curtain as Observed by SDO/AIA

    E-print Network

    Srivastava, A K

    2013-01-01

    We present rare observational evidence of vertical kink oscillations in a laminar and diffused large-scale plasma curtain as observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). The X6.9 class flare in the Active Region 11263 on 09 August 2011, induces a global large-scale disturbance that propagates in a narrow lane above the plasma curtain and creates a low density region that appears as a dimming in the observational image data. This large-scale propagating disturbance acts as a non-periodic driver that interacts asymmetrically and obliquely with the top of the plasma curtain, and triggers the observed oscillations. In the deeper layers of the curtain, we find evidence of vertical kink oscillations with two periods (795 s and 530 s). On the magnetic surface of the curtain where the density is inhomogeneous due to the coronal dimming, non-decaying vertical oscillations are also observed (period $\\approx$ 763-896 s). We infer that the global large-scale disturbanc...

  14. Gain of circularly polarised arrays composed of linearly polarised elements

    NASA Astrophysics Data System (ADS)

    Hall, P. S.; Huang, J.; Rammos, E.; Roederer, A.

    1989-01-01

    The gain of circularly polarized (CP) array antennas realized by proper phasing of sequentially rotated linearly polarized (LP) elements is compared to that of arrays using CP elements and demonstrated by calculations for microstrip patch elements. When element spacing is large and array size is small, the advantages of LP elements are offset by the significant reduction in gain due to high cross polarized lobes in the diagonal planes. For large arrays of closely spaced elements, this gain loss reduces to a negligible amount. However, for spacings above a critical value of about 0.7 wavelengths, unacceptably high gain losses will be incurred.

  15. Evaluation of the Diurnal Evolution of the Size of Tropical Convective Systems in Large Domain, High Resolution Simulations using Observations of Outgoing Longwave Radiation

    NASA Astrophysics Data System (ADS)

    Pearson, K.; Hogan, R.; Allan, R.; Holloway, C. E.; Lister, G.

    2010-12-01

    A long-standing problem in climate models is the failure to capture either the correct diurnal cycle in convective clouds or the growth of individual cells into larger scale complexes. Cascade is a multi-institution project to study the formation and development of tropical convective systems using high-resolution numerical modeling (down to 1.5~km) run over large domains ( ˜2000×2000~km) and observations. As one element of this, we have developed a technique for visualizing and testing the diurnal cycle in the size of convective cloud systems using observations of outgoing longwave radiation. This has been applied to a 2006 test case over Africa using GERB observations and models run with differing configurations and resolutions. We are now applying this to a large domain simulation of the Maritime continent covering several weeks during April 2009 comparing with TRMM observations. The image shows a comparison of the Met Office Unified Model run at 4~km and 12~km resolution, with and without convective parametrization respectively, for the West Africa test case. The grayscale represents the anomaly in the number of systems falling into each lengthscale bin against time. The middle panel is derived from observations by the Geostationary Earth Radiation Budget (GERB) instrument. It shows a broad upward stripe reflecting growth from smaller to larger systems beginning in the late afternoon. The 12~km model shows the effect of the parametrization scheme with systems of all sizes peaking at similar times much earlier than the observations. The 4~km model bears much closer comparison to the observations with growth in the middle to large size range occurring at a similar time to the observations. The small scale behavior, however, is affected by an unrealistic "shattering" of the large systems into many fragments in the early morning rather than a gradual decay.

  16. Circular RNA biogenesis can proceed through an exon-containing lariat precursor

    PubMed Central

    Barrett, Steven P; Wang, Peter L; Salzman, Julia

    2015-01-01

    Pervasive expression of circular RNA is a recently discovered feature of eukaryotic gene expression programs, yet its function remains largely unknown. The presumed biogenesis of these RNAs involves a non-canonical ‘backsplicing’ event. Recent studies in mammalian cell culture posit that backsplicing is facilitated by inverted repeats flanking the circularized exon(s). Although such sequence elements are common in mammals, they are rare in lower eukaryotes, making current models insufficient to describe circularization. Through systematic splice site mutagenesis and the identification of splicing intermediates, we show that circular RNA in Schizosaccharomyces pombe is generated through an exon-containing lariat precursor. Furthermore, we have performed high-throughput and comprehensive mutagenesis of a circle-forming exon, which enabled us to discover a systematic effect of exon length on RNA circularization. Our results uncover a mechanism for circular RNA biogenesis that may account for circularization in genes that lack noticeable flanking intronic secondary structure. DOI: http://dx.doi.org/10.7554/eLife.07540.001 PMID:26057830

  17. Combined MIPAS (airborne/satellite), CALIPSO and in situ study on large potential NAT particles observed in early Arctic winter stratosphere in December 2011

    NASA Astrophysics Data System (ADS)

    Woiwode, Wolfgang; Höpfner, Michael; Pitts, Michael; Poole, Lamont; Oelhaf, Hermann; Molleker, Sergej; Borrmann, Stephan; Ebersoldt, Andreas; Frey, Wiebke; Gulde, Thomas; Maucher, Guido; Piesch, Christof; Sartorius, Christian; Orphal, Johannes

    2015-04-01

    The understanding of the characteristics of large HNO3-containing particles (potential 'NAT-rocks') involved in vertical redistribution of HNO3 in the polar winter stratosphere is limited due to the difficult accessibility of these particles by observations. While robust polar stratospheric cloud (PSC) classification schemes exist for observations by the space-borne lidar aboard CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) as well as for the passive mid-infrared limb observations by MIPAS (Michelson Interferometer for Passive Atmospheric Sounding), these observations are hardly exploited for the detection of large (diameter >10 ?m) NAT particles. This is due to the facts that these particles have low overall number densities, resulting in weak detectable signatures, and that the physical characteristics of these particles (i.e. shape, morphology, HNO3-content and optical characteristics) are uncertain. We investigate collocated and complementary observations of a low-density potential large NAT particle field by the space-borne instruments CALIPSO and MIPAS-ENVISAT as well as the airborne observations by the limb-sounder MIPAS-STR and the in situ particle probe FSSP-100 (Forward Scattering Spectrometer Probe 100) aboard the high-altitude aircraft Geophysica. The observations aboard the Geophysica on 11 December 2011 associated to ESSenCe (ESa Sounder Campaign 2011) provided us the unique opportunity to study in detail the lower boundary region of a PSC where large potential NAT particles (>20 ?m in diameter) were detected in situ. We analyse the ambient temperatures and gas-phase composition (HNO3 and H2O), the signatures of the observed particles in the CALIPSO and MIPAS observations, the HNO3-content of these particles suggested by the FSSP-100 and MIPAS-STR observations, and focus on the spectral fingerprint of these particles in the MIPAS-STR observations. While the spectral characterisation of the observed particles is subject of ongoing work, our results support that these particles consist of NAT and that the particle shape plays a crucial role.

  18. THE CIRCULAR POLARIZATION OF SAGITTARIUS A* AT SUBMILLIMETER WAVELENGTHS

    SciTech Connect

    Munoz, D. J.; Moran, J. M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Marrone, D. P. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Rao, R., E-mail: dmunoz@cfa.harvard.edu [Submillimeter Array, Academia Sinica Institute of Astronomy and Astrophysics, 645 N. Aohoku Place, Hilo, HI 96720 (United States)

    2012-02-01

    We report the first detections of circularly polarized emission at submillimeter wavelengths from the compact radio source and supermassive black hole candidate Sgr A* at a level of 1.2% {+-} 0.3% at 1.3 mm wavelength (230 GHz) and 1.6% {+-} 0.3% at 860 {mu}m (345 GHz) with the same handedness, left circular polarization (LCP), as observed at all lower frequencies (1.4-15 GHz). The observations, taken with the Submillimeter Array in multiple epochs, also show simultaneous linear polarization (LP) at both wavelengths of about 6%. These properties differ sharply from those at wavelengths longer than 1 cm (frequencies below 30 GHz), where weak circular polarization (CP) ({approx}0.5%) dominates over LP, which is not detected at similar fractional limits. We describe an extensive set of tests to ensure the accuracy of our measurements. We find no CP in any other source, including the bright quasar 1924-292, which traces the same path on the sky as Sgr A* and therefore should be subject to identical systematic errors originating in the instrument frame. Since a relativistic synchrotron plasma is expected to produce little CP, the observed CP is probably generated close to the event horizon by the Faraday conversion process. We use a simple approximation to show that the phase shift associated with Faraday conversion can be nearly independent of frequency, a sufficient condition to make the handedness of CP independent of frequency. Because the size of the {tau} = 1 surface changes by more than an order of magnitude between 1.4 and 345 GHz, the magnetic field must be coherent over such scales to consistently produce LCP. To improve our understanding of the environment of SgrA* critical future measurements includes determining whether the Faraday rotation deviates from a {lambda}{sup 2} dependence in wavelength and whether the circular and linear components of the flux density are correlated.

  19. The Circular Polarization of Sagittarius A* at Submillimeter Wavelengths

    NASA Astrophysics Data System (ADS)

    Muñoz, D. J.; Marrone, D. P.; Moran, J. M.; Rao, R.

    2012-02-01

    We report the first detections of circularly polarized emission at submillimeter wavelengths from the compact radio source and supermassive black hole candidate Sgr A* at a level of 1.2% ± 0.3% at 1.3 mm wavelength (230 GHz) and 1.6% ± 0.3% at 860 ?m (345 GHz) with the same handedness, left circular polarization (LCP), as observed at all lower frequencies (1.4-15 GHz). The observations, taken with the Submillimeter Array in multiple epochs, also show simultaneous linear polarization (LP) at both wavelengths of about 6%. These properties differ sharply from those at wavelengths longer than 1 cm (frequencies below 30 GHz), where weak circular polarization (CP) (~0.5%) dominates over LP, which is not detected at similar fractional limits. We describe an extensive set of tests to ensure the accuracy of our measurements. We find no CP in any other source, including the bright quasar 1924-292, which traces the same path on the sky as Sgr A* and therefore should be subject to identical systematic errors originating in the instrument frame. Since a relativistic synchrotron plasma is expected to produce little CP, the observed CP is probably generated close to the event horizon by the Faraday conversion process. We use a simple approximation to show that the phase shift associated with Faraday conversion can be nearly independent of frequency, a sufficient condition to make the handedness of CP independent of frequency. Because the size of the ? = 1 surface changes by more than an order of magnitude between 1.4 and 345 GHz, the magnetic field must be coherent over such scales to consistently produce LCP. To improve our understanding of the environment of SgrA* critical future measurements includes determining whether the Faraday rotation deviates from a ?2 dependence in wavelength and whether the circular and linear components of the flux density are correlated.

  20. Chandra And HST Observations of Gamma-Ray Blazars: Comparing Jet Emission at Small And Large Scales

    SciTech Connect

    Tavecchio, Fabrizio; Maraschi, L.; Wolter, A.; /Brera Observ.; Cheung, C.C.; /KIPAC, Menlo Park; Sambruna, R.M.; /NASA, Goddard; Urry, C.M.; /Yale U., Dept. Astron.

    2007-03-20

    We present new Chandra and HST data for four gamma-ray blazars selected on the basis of radio morphology with the aim of revealing X-ray and optical emission from their jets at large scales. All the sources have been detected. Spectral Energy Distributions of the large scale jets are obtained as well as new X-ray spectra for the blazar cores. Modeling for each object the core (sub-pc scale) and large-scale ({approx}> 100 kpc) jet SEDs, we derive the properties of the same jet at the two scales. The comparison of speeds and powers at different scales supports a simple scenario for the dynamics and propagation of high power relativistic jets.

  1. Circular Permutation of the Trp-cage: Fold Rescue upon Addition of a Hydrophobic Staple

    PubMed Central

    Byrne, Aimee; Kier, Brandon L.; Williams, D. V.; Scian, Michele; Andersen, Niels H.

    2013-01-01

    The Trp-cage, at 20 residues in length, is generally acknowledged as the smallest fully protein-like folding motif. Linking the termini by a two-residue unit and excising one residue affords circularly permuted sequences that adopt the same structure. This represents the first successful circular permutation of any fold of less than 50-residue length. As was observed for the original topology, a hydrophobic staple near the chain termini is required for enhanced fold stability. PMID:24376912

  2. LED downlights with non-circular spots

    NASA Astrophysics Data System (ADS)

    Parkyn, William A.; Pelka, David G.

    2005-09-01

    The ubiquitous downlight inhabits our ceilings by the millions. Hot, inefficient, and electrically wasteful, it is next in line for replacement by the latest high-brightness, high-efficacy white LEDs. The conventional downlight configuration of a large incandescent spotlight in a low-cost, ceiling-recessed metal can, represents the culmination of old technology, fated never to improve significantly. Incandescent downlights add greatly both to direct and indirect electrical consumption, with the lamps requiring relatively frequent replacement. The small size of LED emitters means small optical elements can produce much higher-quality beams than incandescent spotlight-lamps can produce. Herein we introduce compact high-luminosity LED downlights with lenses that deliver uniform illumination to delimited targets such as tables. One version utilizes circular lenses and micro-diffuser films to deliver square outputs. The other uses lenses cut to the target shape. In particular, one of these lenses is the first to offer a semicircular spot suitable for gambling tables.

  3. Observations of the 2.2-micron emission from the halo of NGC 4244 at large galactocentric distances

    Microsoft Academic Search

    J. W. Bergstrom; R. D. Gehrz; T. J. Jones

    1992-01-01

    Observations of 2.2-micron emission from the halo of the edge-on spiral galaxy NGC 4244 are reported. These observations were made at larger radii from the center of the galaxy and with a smaller beam than reported in previous studies. The emission detected is consistent with the de Vaucouleurs r exp 1\\/4 law, and the mass-to-light ratio given by the present

  4. Analysis of small- and large-scale increases of reactive nitrogen observed during the Second Airborne Arctic Stratospheric Expedition

    Microsoft Academic Search

    J. Zheng; A. J. Weinheimer; B. A. Ridley; S. C. Liu; G. W. Sachseft; B. E. Anderson; J. E. Collins Jr

    1996-01-01

    An analysis of the data obtained during AASE II was made to characterize small- (fix < 24 km) and large-scale (30 < fix < 260 km) increases of reactive nitrogen species. By using the NOx\\/NOy ratio, the increases were classified into fresh emissions and aged air parcels. The sources of the NOy increases were then assessed by the freshness of

  5. Isotopic outcomes of N-body accretion simulations: Constraints on equilibration processes during large impacts from Hf\\/W observations

    Microsoft Academic Search

    F. Nimmo; C. B. Agnor

    2006-01-01

    Most estimates of planetary core formation timescales using hafnium–tungsten (Hf–W) isotopes employ analytical expressions assuming either continuous planetary growth or instantaneous core formation. In contrast, dynamical modelling of planetary accretion suggests that the final stage of terrestrial planet formation is punctuated by multiple large and stochastic impacts. Such giant impacts have significant thermal and isotopic consequences. We present a framework

  6. The present-day flux of large meteoroids on the lunar surface--A synthesis of models and observational techniques

    E-print Network

    The present-day flux of large meteoroids on the lunar surface--A synthesis of models, Invalidenstr. 43, 10115 Berlin, Germany k School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA a r t i c l e i n f o Article history: Received 2 March 2012 Accepted 5 October

  7. NON-ZEEMAN CIRCULAR POLARIZATION OF MOLECULAR ROTATIONAL SPECTRAL LINES

    SciTech Connect

    Houde, Martin; Jones, Scott; Rajabi, Fereshte [Department of Physics and Astronomy, The University of Western Ontario, London, ON, N6A 3K7 (Canada)] [Department of Physics and Astronomy, The University of Western Ontario, London, ON, N6A 3K7 (Canada); Hezareh, Talayeh [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany)] [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany)

    2013-02-10

    We present measurements of circular polarization from rotational spectral lines of molecular species in Orion KL, most notably {sup 12}CO (J = 2 {yields} 1), obtained at the Caltech Submillimeter Observatory with the Four-Stokes-Parameter Spectral Line Polarimeter. We find levels of polarization of up to 1%-2% in general; for {sup 12}CO (J = 2 {yields} 1) this level is comparable to that of linear polarization also measured for that line. We present a physical model based on resonant scattering in an attempt to explain our observations. We discuss how slight differences in scattering amplitudes for radiation polarized parallel and perpendicular to the ambient magnetic field, responsible for the alignment of the scattering molecules, can lead to the observed circular polarization. We also show that the effect is proportional to the square of the magnitude of the plane of the sky component of the magnetic field and therefore opens up the possibility of measuring this parameter from circular polarization measurements of Zeeman insensitive molecules.

  8. Strong interaction between plants induces circular barren patches: fairy circles.

    PubMed

    Fernandez-Oto, C; Tlidi, M; Escaff, D; Clerc, M G

    2014-10-28

    Fairy circles consist of isolated or randomly distributed circular areas devoid of any vegetation. They are observed in vast territories in southern Angola, Namibia and South Africa. We report on the formation of fairy circles, and we interpret them as localized structures with a varying plateau size as a function of the aridity. Their stabilization mechanism is attributed to a combined influence of the bistability between the bare state and the uniformly vegetation state, and Lorentzian-like non-local coupling that models the competition between plants. We show how a circular shape is formed, and how the aridity level influences the size of fairy circles. Finally, we show that the proposed mechanism is model-independent. PMID:25246685

  9. Evidence of low-latitude daytime large-scale traveling ionospheric disturbances observed by high-frequency multistatic backscatter sounding system during a geomagnetically quiet period

    NASA Astrophysics Data System (ADS)

    Zhou, Chen; Zhao, Zhengyu; Yang, Guobin; Chen, Gang; Hu, Yaogai; Zhang, Yuannong

    2012-06-01

    Observations from the high-frequency multistatic backscatter sounding radars on a geomagnetically quiet day (minimum Dst = -14 nT) captured the anti-equatorward propagation of daytime large-scale traveling ionospheric disturbance (LSTID) at the low-latitude regions. The observed LSTID was characterized approximately by a meridional propagation speed of 347 ± 78 m/s and azimuthal angle of -4.7 ± 27.6° (counterclockwise from north), with a period of 76 min and a wavelength of 1583 ± 354 km by means of maximum entropy cross-spectral analysis. Vertical phase velocity was also evaluated to be <˜42 m/s through the Doppler measurements. These results provide evidence that the low-latitude ionosphere can undergo large-scale perturbations even under geomagnetically quiet conditions. We suggest that this observed LSTID could be due to the secondary gravity waves from thermospheric body forces created from the dissipation of primary gravity waves from deep tropospheric convection.

  10. A table-top ultrashort light source in the extreme ultraviolet for circular dichroism experiments

    NASA Astrophysics Data System (ADS)

    Ferré, A.; Handschin, C.; Dumergue, M.; Burgy, F.; Comby, A.; Descamps, D.; Fabre, B.; Garcia, G. A.; Géneaux, R.; Merceron, L.; Mével, E.; Nahon, L.; Petit, S.; Pons, B.; Staedter, D.; Weber, S.; Ruchon, T.; Blanchet, V.; Mairesse, Y.

    2015-02-01

    Circular dichroism in the extreme ultraviolet range is broadly used as a sensitive structural probe of matter, from the molecular photoionization of chiral species to the magnetic properties of solids. Extending such techniques to the dynamical regime has been a long-standing quest of solid-state physics and physical chemistry, and was only achieved very recently thanks to the development of femtosecond circular extreme ultraviolet sources. Only a few large facilities, such as femtosliced synchrotrons or free-electron lasers, are currently able to produce such pulses. Here, we propose a new compact and accessible alternative solution: resonant high-order harmonic generation of an elliptical laser pulse. We show that this process, based on a simple optical set-up, delivers bright, coherent, ultrashort, quasi-circular pulses in the extreme ultraviolet. We use this source to measure photoelectron circular dichroism on chiral molecules, opening the route to table-top time-resolved femtosecond and attosecond chiroptical experiments.

  11. Large magnetic moment observed in Co-doped ZnO nanocluster-assembled thin films at room temperature

    Microsoft Academic Search

    Z. W. Zhao; B. K. Tay; J. S. Chen; J. F. Hu; B. C. Lim; G. P. Li

    2007-01-01

    Co-doped ZnO nanocluster-assembled films were deposited by nanocluster-beam deposition. Zn0.986Co0.014O nanoclusters remained wurtzite in structure with size of 5 nm. Compared with bulk ZnO, a blueshift of 0.28 eV was observed in the absorption edge of the film. Two photo-luminescence bands at 378 and 510 nm were detected. Room-temperature ferromagnetism was observed in doped ZnO nanocluster-assembled film. Moreover, it exhibited

  12. Observation of the Nonlinear Saturation of Langmuir Waves Driven by Ponderomotive Force in a Large Scale Plasma

    NASA Astrophysics Data System (ADS)

    Kirkwood, R. K.; Montgomery, D. S.; Afeyan, B. B.; Moody, J. D.; MacGowan, B. J.; Joshi, C.; Wharton, K. B.; Glenzer, S. H.; Williams, E. A.; Young, P. E.; Kruer, W. L.; Estabrook, K. G.; Berger, R. L.

    1999-10-01

    We report the observation of nonlinear saturation of Langmuir waves produced by a probe laser beam interacting with a high intensity pumping laser beam. Amplification of the probe beam is observed and interpreted as scattering of pump energy by a Langmuir wave that is produced by the beating of the two beams. It is found that, as the probe beam amplitude is increased, the scattering and Langmuir wave amplitude do not increase proportionally, demonstrating that the wave is nonlinearly saturated consistent with saturation by secondary-ion-wave instabilities.

  13. Large-scale variations of the low-latitude ionosphere during the October–November 2003 superstorm: Observational results

    Microsoft Academic Search

    C. H. Lin; A. D. Richmond; J. Y. Liu; H. C. Yeh; L. J. Paxton; G. Lu; H. F. Tsai; S.-Y. Su

    2005-01-01

    The GPS-derived total electron content (TEC), ion drift measurements from the ROCSAT-1 spacecraft at around 600 km altitude, and far-ultraviolet airglow measured by the Global Ultraviolet Imager (GUVI) carried on board the NASA TIMED satellite are utilized for studying large disturbances of the low-latitude ionosphere during the October–November 2003 superstorm period. Two chains of GPS receivers, one in the American

  14. Large-scale variations of the low-latitude ionosphere during the October-November 2003 superstorm: Observational results

    Microsoft Academic Search

    C. H. Lin; A. D. Richmond; J. Y. Liu; H. C. Yeh; L. J. Paxton; G. Lu; H. F. Tsai; S.-Y. Su

    2005-01-01

    The GPS-derived total electron content (TEC), ion drift measurements from the ROCSAT-1 spacecraft at around 600 km altitude, and far-ultraviolet airglow measured by the Global Ultraviolet Imager (GUVI) carried on board the NASA TIMED satellite are utilized for studying large disturbances of the low-latitude ionosphere during the October-November 2003 superstorm period. Two chains of GPS receivers, one in the American

  15. Analysis of small-and large-scale increases of reactive nitrogen observed during the Second Airborne Arctic Stratospheric Expedition

    Microsoft Academic Search

    J. Zheng; A. J. Weinheimer; B. A. Ridley; S. C. Liu; G. W. Sachse; B. E. Anderson; J. E. Collins

    1996-01-01

    An analysis of the data obtained during AASE II was made to characterize small- (deltax<24 km) and large-scale (30

  16. Afterglow Observations of Fermi Large Area Telescope Gamma-ray Bursts and the Emerging Class of Hyper-energetic Events

    NASA Astrophysics Data System (ADS)

    Cenko, S. B.; Frail, D. A.; Harrison, F. A.; Haislip, J. B.; Reichart, D. E.; Butler, N. R.; Cobb, B. E.; Cucchiara, A.; Berger, E.; Bloom, J. S.; Chandra, P.; Fox, D. B.; Perley, D. A.; Prochaska, J. X.; Filippenko, A. V.; Glazebrook, K.; Ivarsen, K. M.; Kasliwal, M. M.; Kulkarni, S. R.; LaCluyze, A. P.; Lopez, S.; Morgan, A. N.; Pettini, M.; Rana, V. R.

    2011-05-01

    We present broadband (radio, optical, and X-ray) light curves and spectra of the afterglows of four long-duration gamma-ray bursts (GRBs GRBs 090323, 090328, 090902B, and 090926A) detected by the Gamma-Ray Burst Monitor and Large Area Telescope (LAT) instruments on the Fermi satellite. With its wide spectral bandpass, extending to GeV energies, Fermi is sensitive to GRBs with very large isotropic energy releases (1054 erg). Although rare, these events are particularly important for testing GRB central-engine models. When combined with spectroscopic redshifts, our afterglow data for these four events are able to constrain jet collimation angles, the density structure of the circumburst medium, and both the true radiated energy release and the kinetic energy of the outflows. In agreement with our earlier work, we find that the relativistic energy budget of at least one of these events (GRB 090926A) exceeds the canonical value of 1051 erg by an order of magnitude. Such energies pose a severe challenge for models in which the GRB is powered by a magnetar or a neutrino-driven collapsar, but remain compatible with theoretical expectations for magnetohydrodynamical collapsar models (e.g., the Blandford-Znajek mechanism). Our jet opening angles (?) are similar to those found for pre-Fermi GRBs, but the large initial Lorentz factors (?0) inferred from the detection of GeV photons imply ??0 ? 70-90, values which are above those predicted in magnetohydrodynamic models of jet acceleration. Finally, we find that these Fermi-LAT events preferentially occur in a low-density circumburst environment, and we speculate that this might result from the lower mass-loss rates of their lower-metallicity progenitor stars. Future studies of Fermi-LAT afterglows at radio wavelengths with the order-of-magnitude improvement in sensitivity offered by the Extended Very Large Array should definitively establish the relativistic energy budgets of these events.

  17. Observation of a large electric dipole moment produced in electron-transfer collisions of H\\/sup +\\/ on He

    Microsoft Academic Search

    C. C. Havener; W. B. Westerveld; J. S. Risley; N. H. Tolk; J. C. Tully

    1982-01-01

    The measured intensity and polarization of Balmer-alpha radiation resulting from (40--80)-keV collisions of H\\/sup +\\/ on He exhibited a strong dependence with electric fields applied axially along the beam direction. With use of a density matrix formalism the collisionally produced electric dipole moment for the n = 3 state was found to be large, reaching 4.4eaâ at the lowest collision

  18. Large-Scale Dynamics of the Magnetospheric Boundary: Comparisons between Global MHD Simulation Results and ISTP Observations

    NASA Technical Reports Server (NTRS)

    Berchem, J.; Raeder, J.; Ashour-Abdalla, M.; Frank, L. A.; Paterson, W. R.; Ackerson, K. L.; Kokubun, S.; Yamamoto, T.; Lepping, R. P.

    1998-01-01

    Understanding the large-scale dynamics of the magnetospheric boundary is an important step towards achieving the ISTP mission's broad objective of assessing the global transport of plasma and energy through the geospace environment. Our approach is based on three-dimensional global magnetohydrodynamic (MHD) simulations of the solar wind-magnetosphere- ionosphere system, and consists of using interplanetary magnetic field (IMF) and plasma parameters measured by solar wind monitors upstream of the bow shock as input to the simulations for predicting the large-scale dynamics of the magnetospheric boundary. The validity of these predictions is tested by comparing local data streams with time series measured by downstream spacecraft crossing the magnetospheric boundary. In this paper, we review results from several case studies which confirm that our MHD model reproduces very well the large-scale motion of the magnetospheric boundary. The first case illustrates the complexity of the magnetic field topology that can occur at the dayside magnetospheric boundary for periods of northward IMF with strong Bx and By components. The second comparison reviewed combines dynamic and topological aspects in an investigation of the evolution of the distant tail at 200 R(sub E) from the Earth.

  19. Observations of wild hunting behaviour and bioluminescence of a large deep-sea, eight-armed squid, Taningia danae

    PubMed Central

    Kubodera, Tsunemi; Koyama, Yasuhiro; Mori, Kyoichi

    2007-01-01

    Our newly developed underwater high definition video camera system took the first live images of adults of the mesopelagic large squid, Taningia danae, between 240 and 940?m deep off Ogasawara Islands, western North Pacific. The resulting footage includes attacking and bioluminescence behaviours, and reveals that T. danae is far from the sluggish neutrally buoyant deep-sea squid previously suspected. It can actively swim both forward and backward freely by flapping its large muscular triangular fins and changes direction quickly through bending its flexible body. It can attain speeds of 2–2.5?m?s?1 (7.2–9?km?h?1) when attacking bait rigs. They emitted short bright light flashes from their large arm-tip photophores before final assault, which might act as a blinding flash for prey as well as a means of measuring target distance in a dark deep-sea environment. They also emitted long and short glows separated by intervals while wandering around the double torch lights attached to the bait rig, suggestive of potential courtship behaviours during mating. PMID:17301020

  20. Variability of the large scale general circulation of the Mediterranean Sea from observations and modelling: a review

    Microsoft Academic Search

    N. Pinardi; E. Masetti

    2000-01-01

    In this paper we present an overview of the most recent findings about the Mediterranean Sea present-day circulation structure. Both historical observations and numerical model simulations are presented, outlining the differences and agreement. The model simulations are presented for both an eddy resolving and a coarse resolution numerical model and the results are intercompared. The importance of the mesoscales in

  1. Can the cosmological constant be mimicked by smooth large-scale inhomogeneities for more than one observable?

    SciTech Connect

    Romano, Antonio Enea, E-mail: aer@yukawa.kyoto-u.ac.jp [Yukawa Institute for Theoretical Physics and Physics Department, Kyoto University, Kyoto 606-8502 (Japan)

    2010-05-01

    As an alternative to dark energy it has been suggested that we may be at the center of an inhomogeneous isotropic universe described by a Lemaitre-Tolman-Bondi (LTB) solution of Einstein's field equations. In order to test such an hypothesis we calculate the low redshift expansion of the luminosity distance D{sub L}(z) and the redshift spherical shell mass density mn(z) for a central observer in a LTB space without cosmological constant and show how they cannot fit the observations implied by a ?CDM model if the conditions to avoid a weak central singularity are imposed, i.e. if the matter distribution is smooth everywhere. Our conclusions are valid for any value of the cosmological constant, not only for ?{sub ?} > 1/3 as implied by previous proofs that q{sup app}{sub 0} has to be positive in a smooth LTB space, based on considering only the luminosity distance. The observational signatures of smooth LTB matter dominated models are fundamentally different from the ones of ?CDM models not only because it is not possible to reproduce a negative apparent central deceleration q{sup app}{sub 0}, but because of deeper differences in their space-time geometry which make impossible solve the inversion problem when more than one observable is considered, and emerge at any redshift, not only for z = 0.

  2. New observations of electromagnetic harmonic ELF emissions in the ionosphere by the DEMETER satellite during large magnetic storms

    E-print Network

    Santolik, Ondrej

    New observations of electromagnetic harmonic ELF emissions in the ionosphere by the DEMETER; published 4 August 2006. [1] DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake scientific payload allows to measure electromagnetic waves and plasma parameters. During the strong magnetic

  3. 21 CFR 606.122 - Instruction circular.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...Instructions to administer a suitable plasma volume expander if Red Blood Cells are...contain: (1) The approximate volume of plasma from which a sample unit of Platelets...after entering the container. (m) For Plasma, the instruction circular shall...

  4. 21 CFR 606.122 - Instruction circular.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...Instructions to administer a suitable plasma volume expander if Red Blood Cells are...contain: (1) The approximate volume of plasma from which a sample unit of Platelets...after entering the container. (m) For Plasma, the instruction circular shall...

  5. 21 CFR 606.122 - Instruction circular.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...Instructions to administer a suitable plasma volume expander if Red Blood Cells are...contain: (1) The approximate volume of plasma from which a sample unit of Platelets...after entering the container. (m) For Plasma, the instruction circular shall...

  6. Dual frequency launcher for circularly polarized antenna

    NASA Astrophysics Data System (ADS)

    Chen, Ming H.

    1989-10-01

    A dual frequency antenna feed is formed from a central, circular waveguide connected to the flat boundry of circular, disk-shaped resonant cavity. A second circular waveguide is connected one end of a disk-shaped resonant cavity. Energy of one frequency enters and exits the cavity along the common axis of the waveguides. Energy of the second frequency is introduced to the same resonant cavity by way of a plurality of bandpass filters, also connected to the cavity. This energy enters by way of slots in the cylindrical walls of the cavity. The central circular waveguide is propagating at one frequency but cut off at the second frequency. These bandpass filters are at this pass band for the second frequency, but at the rejection band for the first frequency. Therefore, the isolation between these two input ports are obtained.

  7. Circular polarization in the optical afterglow of GRB 121024A.

    PubMed

    Wiersema, K; Covino, S; Toma, K; van der Horst, A J; Varela, K; Min, M; Greiner, J; Starling, R L C; Tanvir, N R; Wijers, R A M J; Campana, S; Curran, P A; Fan, Y; Fynbo, J P U; Gorosabel, J; Gomboc, A; Götz, D; Hjorth, J; Jin, Z P; Kobayashi, S; Kouveliotou, C; Mundell, C; O'Brien, P T; Pian, E; Rowlinson, A; Russell, D M; Salvaterra, R; di Serego Alighieri, S; Tagliaferri, G; Vergani, S D; Elliott, J; Fariña, C; Hartoog, O E; Karjalainen, R; Klose, S; Knust, F; Levan, A J; Schady, P; Sudilovsky, V; Willingale, R

    2014-05-01

    Gamma-ray bursts (GRBs) are most probably powered by collimated relativistic outflows (jets) from accreting black holes at cosmological distances. Bright afterglows are produced when the outflow collides with the ambient medium. Afterglow polarization directly probes the magnetic properties of the jet when measured minutes after the burst, and it probes the geometric properties of the jet and the ambient medium when measured hours to days after the burst. High values of optical polarization detected minutes after the burst of GRB 120308A indicate the presence of large-scale ordered magnetic fields originating from the central engine (the power source of the GRB). Theoretical models predict low degrees of linear polarization and no circular polarization at late times, when the energy in the original ejecta is quickly transferred to the ambient medium and propagates farther into the medium as a blast wave. Here we report the detection of circularly polarized light in the afterglow of GRB 121024A, measured 0.15?days after the burst. We show that the circular polarization is intrinsic to the afterglow and unlikely to be produced by dust scattering or plasma propagation effects. A possible explanation is to invoke anisotropic (rather than the commonly assumed isotropic) electron pitch-angle distributions, and we suggest that new models are required to produce the complex microphysics of realistic shocks in relativistic jets. PMID:24776800

  8. Physics Classroom: Applications of Circular Motion

    NSDL National Science Digital Library

    Henderson, Tom

    Created by Tom Henderson of Physics Classroom.com, this student tutorial illustrates how circular motion principles can be combined with Newton's Second Law to analyze physical situations. The author uses free-body diagrams to analyze various forces acting upon a car moving in a circle. Two algebraic problems and detailed solutions are provided, plus a five-step model for solving circular motion problems. This is just one subset of a much larger collection of physics problems and illustrations.

  9. Single particle dynamics in circular accelerators

    SciTech Connect

    Ruth, R.D.

    1986-10-01

    The purpose of this paper is to introduce the reader to the theory associated with the transverse dynamics of single particle, in circular accelerators. The discussion begins with a review of Hamiltonian dynamics and canonical transformations. The case of a single particle in a circular accelerator is considered with a discussion of non-linear terms and chromaticity. The canonical perturbation theory is presented and nonlinear resonances are considered. Finally, the concept of renormalization and residue criterion are examined. (FI)

  10. Fermi Large Area Telescope Observations of the Supernova Remnant W28 (G6.4-0.1)

    Microsoft Academic Search

    A. A. Abdo; M. Ackermann; M. Ajello; A. Allafort; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; K. Bechtol; R. Bellazzini; B. Berenji; R. D. Blandford; E. D. Bloom; E. Bonamente; A. W. Borgland; A. Bouvier; T. J. Brandt; J. Bregeon; M. Brigida; P. Bruel; R. Buehler; S. Buson; G. A. Caliandro; R. A. Cameron; P. A. Caraveo; S. Carrigan; J. M. Casandjian; C. Cecchi; Ö. Çelik; A. Chekhtman; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; J. Conrad; C. D. Dermer; F. de Palma; E. do Couto e. Silva; P. S. Drell; R. Dubois; D. Dumora; C. Farnier; C. Favuzzi; S. J. Fegan; Y. Fukazawa; Y. Fukui; S. Funk; P. Fusco; F. Gargano; N. Gehrels; S. Germani; N. Giglietto; F. Giordano; T. Glanzman; G. Godfrey; I. A. Grenier; J. E. Grove; S. Guiriec; D. Hadasch; Y. Hanabata; A. K. Harding; E. Hays; D. Horan; R. E. Hughes; G. Jóhannesson; A. S. Johnson; W. N. Johnson; T. Kamae; H. Katagiri; J. Kataoka; J. Knödlseder; M. Kuss; J. Lande; L. Latronico; S.-H. Lee; M. Lemoine-Goumard; M. Llena Garde; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; A. Makeev; M. N. Mazziotta; P. F. Michelson; W. Mitthumsiri; T. Mizuno; A. A. Moiseev; C. Monte; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Murgia; T. Nakamori; P. L. Nolan; J. P. Norris; E. Nuss; M. Ohno; T. Ohsugi; N. Omodei; E. Orlando; J. F. Ormes; M. Ozaki; J. H. Panetta; D. Parent; V. Pelassa; M. Pepe; M. Pesce-Rollins; F. Piron; T. A. Porter; S. Rainò; R. Rando; M. Razzano; A. Reimer; O. Reimer; T. Reposeur; A. Y. Rodriguez; M. Roth; H. F.-W. Sadrozinski; A. Sander; P. M. Saz Parkinson; C. Sgrò; E. J. Siskind; D. A. Smith; P. D. Smith; G. Spandre; P. Spinelli; M. S. Strickman; D. J. Suson; H. Tajima; H. Takahashi; T. Takahashi; T. Tanaka; J. B. Thayer; J. G. Thayer; D. J. Thompson; L. Tibaldo; O. Tibolla; D. F. Torres; G. Tosti; Y. Uchiyama; T. Uehara; T. L. Usher; V. Vasileiou; N. Vilchez; V. Vitale; A. P. Waite; P. Wang; B. L. Winer; K. S. Wood; H. Yamamoto; R. Yamazaki; Z. Yang; T. Ylinen; M. Ziegler

    2010-01-01

    We present detailed analysis of two gamma-ray sources, 1FGL J1801.3-2322c and 1FGL J1800.5-2359c, that have been found toward the supernova remnant (SNR) W28 with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. 1FGL J1801.3-2322c is found to be an extended source within the boundary of SNR W28, and to extensively overlap with the TeV gamma-ray source

  11. Observing large-scale solar surface flows with GONG: Investigation of a key element in solar activity buildup

    NASA Technical Reports Server (NTRS)

    Beck, John G.; Simon, George W.; Hathaway, David H.

    1996-01-01

    The Global Oscillation Network Group (GONG) solar telescope network has begun regular operations, and will provide continuous Doppler images of large-scale nearly-steady motions at the solar surface, primarily those due to supergranulation. Not only the Sun's well-known magnetic network, but also flux diffusion, dispersal, and concentration at the surface appear to be controlled by supergranulation. Through such magnetoconvective interactions, magnetic stresses develop, leading to solar activity. We show a Doppler movie made from a 45.5 hr time series obtained 1995 May 9-10 using data from three of the six GONG sites (Learmonth, Tenerife, Tucson), to demonstrate the capability of this system.

  12. Observation of a large electric dipole moment produced in electron-transfer collisions of H/sup +/ on He

    SciTech Connect

    Havener, C.C.; Westerveld, W.B.; Risley, J.S.; Tolk, N.H.; Tully, J.C.

    1982-04-05

    The measured intensity and polarization of Balmer-alpha radiation resulting from (40--80)-keV collisions of H/sup +/ on He exhibited a strong dependence with electric fields applied axially along the beam direction. With use of a density matrix formalism the collisionally produced electric dipole moment for the n = 3 state was found to be large, reaching 4.4ea/sub 0/ at the lowest collision energy. The center of the electron cloud distribution was found to lag behind the proton.

  13. Circular Data Images for Directional Data

    NASA Technical Reports Server (NTRS)

    Morpet, William J.

    2004-01-01

    Directional data includes vectors, points on a unit sphere, axis orientation, angular direction, and circular or periodic data. The theoretical statistics for circular data (random points on a unit circle) or spherical data (random points on a unit sphere) are a recent development. An overview of existing graphical methods for the display of directional data is given. Cross-over occurs when periodic data are measured on a scale for the measurement of linear variables. For example, if angle is represented by a linear color gradient changing uniformly from dark blue at -180 degrees to bright red at +180 degrees, the color image will be discontinuous at +180 degrees and -180 degrees, which are the same location. The resultant color would depend on the direction of approach to the cross-over point. A new graphical method for imaging directional data is described, which affords high resolution without color discontinuity from "cross-over". It is called the circular data image. The circular data image uses a circular color scale in which colors repeat periodically. Some examples of the circular data image include direction of earth winds on a global scale, rocket motor internal flow, earth global magnetic field direction, and rocket motor nozzle vector direction vs. time.

  14. Observation of Large CP Violation and Evidence for Direct CP Violation in B0-->pi+pi- Decays

    Microsoft Academic Search

    K. Abe; N. Abe; T. Abe; I. Adachi; H. Aihara; K. Akai; M. Akatsu; M. Akemoto; Y. Asano; T. Aso; V. Aulchenko; T. Aushev; A. M. Bakich; Y. Ban; S. Banerjee; A. Bay; I. Bedny; I. Bizjak; A. Bondar; A. Bozek; M. Bracko; T. E. Browder; Y. Chao; K.-F. Chen; B. G. Cheon; R. Chistov; S.-K. Choi; Y. Choi; A. Chuvikov; S. Cole; M. Danilov; J. Dragic; A. Drutskoy; S. Eidelman; V. Eiges; Y. Enari; D. Epifanov; J. Flanagan; K. Furukawa; N. Gabyshev; A. Garmash; T. Gershon; B. Golob; J. Haba; K. Hara; N. C. Hastings; H. Hayashii; M. Hazumi; L. Hinz; T. Hokuue; Y. B. Hsiung; W.-S. Hou; H.-C. Huang; T. Iijima; H. Ikeda; K. Inami; A. Ishikawa; H. Ishino; R. Itoh; H. Iwasaki; M. Iwasaki; Y. Iwasaki; H. Kakuno; T. Kamitani; J. H. Kang; J. S. Kang; P. Kapusta; S. U. Kataoka; N. Katayama; H. Kichimi; T. Kawasaki; A. Kibayashi; H. J. Kim; J. H. Kim; S. K. Kim; K. Kinoshita; P. Koppenburg; S. Korpar; P. Krizan; P. Krokovny; S. Kumar; A. Kuzmin; Y.-J. Kwon; J. S. Lange; G. Leder; S. H. Lee; Y.-J. Lee; T. Lesiak; J. Li; A. Limosani; S.-W. Lin; D. Liventsev; J. MacNaughton; F. Mandl; D. Marlow; H. Matsumoto; T. Matsumoto; A. Matyja; S. Michizono; T. Mimashi; W. Mitaroff; K. Miyabayashi; H. Miyake; H. Miyata; D. Mohapatra; G. R. Moloney; A. Murakami; T. Nagamine; Y. Nagasaka; T. Nakadaira; T. T. Nakamura; E. Nakano; M. Nakao; H. Nakazawa; Z. Natkaniec; K. Neichi; S. Nishida; O. Nitoh; S. Noguchi; T. Nozaki; S. Ogawa; Y. Ogawa; K. Ohmi; T. Ohshima; N. Ohuchi; K. Oide; T. Okabe; S. Okuno; S. L. Olsen; W. Ostrowicz; H. Ozaki; P. Pakhlov; H. Palka; C. W. Park; N. Parslow; L. E. Piilonen; N. Root; M. Rozanska; H. Sagawa; Y. Sakai; O. Schneider; J. Schümann; C. Schwanda; A. J. Schwartz; S. Semenov; K. Senyo; H. Shibuya; T. Shidara; B. Shwartz; V. Sidorov; J. B. Singh; N. Soni; R. Stamen; S. Stanic; M. Staric; R. Sugahara; K. Sumisawa; T. Sumiyoshi; K. Suzuki; S. Suzuki; O. Tajima; F. Takasaki; K. Tamai; N. Tamura; M. Tanaka; M. Tawada; Y. Teramoto; T. Tomura; T. Tsuboyama; T. Tsukamoto; S. Uehara; T. Uglov; K. Ueno; Y. Unno; S. Uno; G. Varner; K. E. Varvell; C. C. Wang; M.-Z. Wang; Y. Watanabe; B. D. Yabsley; Y. Yamada; A. Yamaguchi; Y. Yamashita; M. Yamauchi; H. Yanai; Heyoung Yang; J. Ying; M. Yokoyama; M. Yoshida; Y. Yusa; C. C. Zhang; Z. P. Zhang; T. Ziegler; D. Zontar; D. Zürcher

    2004-01-01

    We report the first observation of CP violation in B0-->pi+pi- decays based on 152×106 upsilo(4S)-->BB¯ decays collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. We reconstruct a B0-->pi+pi- CP eigenstate and identify the flavor of the accompanying B meson from its decay products. From the distribution of the time intervals between the two B meson decay points,

  15. The Compatibility of Friedmann Cosmological Models with Observed Properties of Gamma-Ray Bursts and a Large Hubble Constant

    NASA Technical Reports Server (NTRS)

    Horack, John M.; Koshut, Thomas M.; Mallozzi, Robert S.; Emslie, A. Gordon; Meegan, Charles A.

    1996-01-01

    The distance scale to cosmic gamma-ray bursts (GRB's) is still uncertain by many orders of magnitude; however, one viable scenario places GRB's at cosmological distances, thereby permitting them to be used as tracers of the cosmological expansion over a significant range of redshifts zeta. Also, several recent measurements of the Hubble constant H(sub 0) appearing in the referred literature report values of 70-80 km/s /Mpc. Although there is significant debate regarding these measurements, we proceed here under the assumption that they are evidence of a large value for H(sub 0). This is done in order to investigate the additional constraints on cosmological models that can be obtained under this hypothesis when combined with the age of the universe and the brightness distribution of cosmological gamma-ray bursts. We show that the range of cosmological models that can be consistent with the GRB brightness distribution, a Hubble constant of 70-80 km/s/Mpc, and a minimum age of the universe of 13-15 Gyr is constrained significantly, largely independent of a wide range of assumptions regarding the evolutionary nature of the burst population. Low-density, Lambda greater than 0 cosmological models with deceleration parameter in the range -1 less than q(sub 0) less than 0 and density parameter sigma(sub 0) in the range approximately equals 0.10-0.25(Omega(sub 0) approximately equals 0.2-0.5) are strongly favored.

  16. Evaluation of InGaN/GaN light-emitting diodes of circular geometry.

    PubMed

    Wang, X H; Fu, W Y; Lai, P T; Choi, H W

    2009-12-01

    Blue GaN light emitting diodes (LEDs) in the shape of cuboids and circular disks have been fabricated by laser micromachining. The proposed circular geometry serves to enhance overall light extraction on a macro-scale and to improve uniformity of the emission pattern due to the rotational symmetry of the chip. Analysis of the chip shaping effect is carried out by ray-tracing simulations and further supported with mathematical modeling using ideal LED models, and subsequently verified with fabricated devices. In comparison, a 10% improvement in overall emission was observed for circular LEDs over the regular cuboids, consistent with simulations and calculations. The measured emission pattern from the circular LED confirms the axial symmetry of the emission beam. PMID:20052154

  17. The Circular Hydraulic Jump in Microgravity

    NASA Technical Reports Server (NTRS)

    Avedisian, C. Thomas

    1996-01-01

    This report summarizes the key experimental results and observations that were obtained under NASA grant NAG 3-1627 from the Fluid Physics Program. The Principle Investigator was Thomas Avedisian. In addition a half-time post-doctoral associate, Ziqun Zhao, was funded for half year. The project monitor was David Chao of the NASA-Lewis Research Center in Cleveland, Ohio. The grant period was originally for one year at $34K and a no-cost extension was applied for and granted for an additional year. The research consisted of an experimental study of the circular hydraulic jump (CHJ) in microgravity using water as the working fluid. The evolution of the CHJ radius was measured during a sudden transition from normal to microgravity in a drop tower. The downstream height of the CHJ was controlled by submerging the target plate in a tank filled with water to the desired depth, and the measurements are compared with an existing theory for the location of the CHJ. Results show that the CHJ diameter is larger in microgravity than normal gravity. The adjustment of the CHJ diameter to a sudden change in gravity occurs over a period of about 200ms for the conditions of the present study, and remains constant thereafter for most of the flow conditions examined. For flow conditions that a CHJ was not first established at normal gravity but which later appeared during the transition tb microgravity, the CHJ diameter was not constant during the period of microgravity but continually changed. Good agreement between measured and predicted CHJ radii is found for normal gravity CHJ radii, but comparatively poorer agreement is observed for the CHJ radii measurements in microgravity.

  18. Large scale motions in electrical discharges

    Microsoft Academic Search

    Mahinder S. Uberoi; Chuen-Yen Chow

    1977-01-01

    Mass motions of a plasma are numerically analyzed for a discharge from a central small screen electrode of circular cross section and two other screen electrodes covering the two ends of a circular tube. In effect, there are two oppositely directed discharges from the central electrode and this simplifies the analysis. Rotational electromagnetic forces cause two large eddies, each with

  19. LIDAR observations of lower stratospheric aerosols over South Africa linked to large scale transport across the southern subtropical barrier

    NASA Astrophysics Data System (ADS)

    Bencherif, H.; Portafaix, T.; Baray, J. L.; Morel, B.; Baldy, S.; Leveau, J.; Hauchecorne, A.; Keckhut, P.; Moorgawa, A.; Michaelis, M. M.; Diab, R.

    2003-04-01

    The study of the variability of stratospheric aerosols and the transfer between the different atmospheric regions improves our understanding of dynamical processes involved in isentropic exchanges that take place episodically in the lower stratosphere through the subtropical barrier. One useful approach consists in combining in situ ground-based and global measurements with numerical analyses. The present paper reports on a case study of a horizontal transfer evidenced first by Rayleigh-Mie LIDAR observations over Durban (/29.9°S, /31.0°E, South Africa). Additional data from MeteoSat and SAGE-2 experiments, and from ECMWF meteorological analysis have been used in this study. Contour advection maps of potential vorticity from the MIMOSA model derived from ECMWF fields, were also used. By the end of April, 1999, LIDAR observations showed that aerosol extinction, in the lower stratosphere, has increased significantly and abnormally in comparison with other LIDAR and SAGE-2 observations recorded for the period from April 20 to June 14, 1999. The dynamical context of this case study seems to exclude the possibility of a local influence of the subtropical jet stream or tropical convection, which could inject air masses enriched with tropospheric aerosols into the stratosphere. On the contrary, a high-resolution model based on PV advection calculations and ECMWF meteorological analyses shows that air masses are isentropically advected from the equatorial zone close to Brazil. They cross the southern barrier of the tropical reservoir due to laminae stretching and reach the southern subcontinent of Africa 5-6 days later.

  20. Constraints on the Galactic Population of TeV Pulsar Wind Nebulae Using Fermi Large Area Telescope Observations

    NASA Astrophysics Data System (ADS)

    Acero, F.; Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Bottacini, E.; Brandt, T. J.; Bregeon, 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 Palma, F.; Dermer, C. D.; Di Venere, L.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Falletti, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grégoire, T.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hayashi, K.; Hays, E.; Hewitt, J.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Inoue, Y.; Jackson, M. S.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Kamae, T.; Kawano, T.; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Marelli, M.; Massaro, F.; Mayer, M.; 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.; 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.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Roth, M.; Rousseau, R.; Saz Parkinson, P. M.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Suson, D. J.; Takahashi, H.; Takeuchi, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Werner, M.; Winer, B. L.; Wood, K. S.; Yang, Z.

    2013-08-01

    Pulsar wind nebulae (PWNe) have been established as the most populous class of TeV ?-ray emitters. Since launch, the Fermi Large Area Telescope (LAT) has identified five high-energy (100 MeV < E < 100 GeV) ?-ray sources as PWNe and detected a large number of PWN candidates, all powered by young and energetic pulsars. The wealth of multi-wavelength data available and the new results provided by Fermi-LAT give us an opportunity to find new PWNe and to explore the radiative processes taking place in known ones. The TeV ?-ray unidentified (UNID) sources are the best candidates for finding new PWNe. Using 45 months of Fermi-LAT data for energies above 10 GeV, an analysis was performed near the position of 58 TeV PWNe and UNIDs within 5° of the Galactic plane to establish new constraints on PWN properties and find new clues on the nature of UNIDs. Of the 58 sources, 30 were detected, and this work provides their ?-ray fluxes for energies above 10 GeV. The spectral energy distributions and upper limits, in the multi-wavelength context, also provide new information on the source nature and can help distinguish between emission scenarios, i.e., between classification as a pulsar candidate or as a PWN candidate. Six new GeV PWN candidates are described in detail and compared with existing models. A population study of GeV PWN candidates as a function of the pulsar/PWN system characteristics is presented.

  1. Vibrational circular dichroism of deoxyoligonucleotides

    SciTech Connect

    Gulotta, M.S.

    1993-01-01

    In this thesis, infrared (vibrational) circular dichroism (VCD) is shown to be a viable technique for examining the secondary structure of deoxyoligonucleotides. In these studies spectra were taken in the 1550--1750 cm[sup [minus]1] carbonyl stretching region. VCD spectra of the low salt conformations of poly(dG)poly(dC), poly(dG-dC)poly(dG-dC), poly(dG-me[sup 5]dC)poly(dG-me[sup 5]dC), and pd(CG)[sub 5] are examined. The B-form VCD spectrum of a GC-deoxyoligonucleotide is characterized by a negative/positive couplet at approximately 1700 cm[sup [minus]1] and 1680 cm[sup [minus]1] respectively. High salt Z-form spectra of poly(dG-dC)poly(dG-dC) and poly(dG-me[sup 5]dC)poly(me[sup 5]dC) are also presented. The author has found that the VCD spectra of poly(dG-dC)poly(dG-dC) and poly(dG-me[sup 5]dC)poly(dG-me[sup 5]dC) in high salt solution varies depending on whether NaCl or MgCl[sub 2] is used to induce the B-Z transition. Left-handed conformations are characterized by a positive/negative couplet which is shifted to lower wavenumbers than the B-form couplet. The Degenerate Extended Coupled Oscillator (DECO) model is used as a means of interpreting the VCD experimental data. From the cartesian coordinates of the carbonyl groups and applying simple coupled oscillator theory, the model determines the interaction energy between these groups as well as the effect of the interactions on the dipole and rotational strengths. From the output of the model, calculated spectra can be generated. The DECO model is shown to account for the B-form VCD spectra but the model is unable to account for the Z-form spectra. The author has attributed the problems with the Z-form calculations to interactions between the oligonucleotide and the salt solution which are not currently taken into account.

  2. Characteristics of large Forbush-type decreases in the cosmic radiation. II - Observations at different heliocentric radial distances

    NASA Technical Reports Server (NTRS)

    Webber, W. R.; Lockwood, J. A.; Jokipii, J. R.

    1986-01-01

    Cosmic ray data from IMP 8, Voyager 1 and 2, Pioneer 10 are used to investigate the heliocentric radial dependence of the characteristics of about 20 Forbush-type transient decreases which occurred from 1978 to 1984. These characteristics include the recovery time, the amplitude, and the time to decrease to minimum. It is found that the average recovery time is about 5 times longer at R = 30 AU than at 1 AU. The magnitudes of the transient decreases are observed to decrease about 1.5 percent/AU on average so that the magnitude of the decrease is half as great at R about 30 AU as at 1 AU. The time for the cosmic ray intensity to decrease to the minimum in the transient decrease is found to be greater at larger distances and is about 5 times longer at R = 30 AU than at 1 AU. The behavior of these effects as a function of radius is obviously related to the evolution of the disturbances causing the transient decreases as they propagate outward. A model of the Forbush-type decrease is proposed to explain the observed radial dependence of the recovery time and time to minimum of the decrease. The implications of these results for understanding the relationship between Forbush-type decreases and the 11-year variation are discussed.

  3. Eruption of a plasma blob, associated M-class flare, and large-scale EUV wave observed by SDO

    E-print Network

    Kumar, Pankaj

    2013-01-01

    We present a multiwavelength study of the formation and ejection of a plasma blob and associated EUV waves in AR NOAA 11176, observed by SDO/AIA and STEREO on 25 March 2011. SDO/AIA images clearly show the formation and ejection of a plasma blob from the lower solar atmosphere at ~9 min prior to the onset of the M1.0 flare. This onset of the M-class flare happened at the site of the blob formation, while the blob was rising in a parabolic path with an average speed of ~300 km/s. The blob also showed twisting and de-twisting motion in the lower corona, and the blob speed varied from ~10-540 km/s. The faster and slower EUV wavefronts were observed in front of the plasma blob during its impulsive acceleration phase. The faster EUV wave propagated with a speed of ~785 to 1020 km/s, whereas the slower wavefront speed varied in between ~245 and 465 km/s. The timing and speed of the faster wave match the shock speed estimated from the drift rate of the associated type II radio burst. The faster wave experiences a re...

  4. No salting-in of lysozyme chloride observed at low ionic strength over a large range of pH.

    PubMed Central

    Retailleau, P; Riès-Kautt, M; Ducruix, A

    1997-01-01

    Solubility of lysozyme chloride was determined in the absence of added salt and in the presence of 0.05-1.2 M NaCl, starting from isoionic lysozyme, which was then brought to pH values from 9 to 3 by addition of HCl. The main observation is the absence of a salting-in region whatever the pH studied. This is explained by a predominant electrostatic screening of the positively charged protein and/or by adsorption of chloride ions by the protein. The solubility increases with the protein net charge at low ionic strength, but the reverse is observed at high ionic strength. The solubility of lysozyme chloride seems to become independent of ionic strength at pH approximately 9.5, which is interpreted as a shift of the isoionic pH (10.8) to an isoelectric pH due to chloride binding. The crystallization at very low ionic strength, where lysozyme crystallizes at supersaturation values as low as 1.1, amplifies the effect of pH on protein solubility. Understanding the effect of the net charge and of ionic strength on protein-protein interactions is valuable not only for protein crystal growth but more generally also for the formation of protein-protein or protein-ligand complexes. PMID:9336211

  5. A comparison of detection sensitivity between ALTAIR and Arecibo meteor observations: Can high power and large aperture radars detect low velocity meteor head-echoes

    Microsoft Academic Search

    Diego Janches; Sigrid Close; Jonathan T. Fentzke

    2008-01-01

    Meteor head-echo observations using High Power and Large Aperture (HPLA) radars have been routinely used for micrometeor studies for over a decade. The head-echo is a signal from the radar-reflective plasma region traveling with the meteoroid and its detection allows for very precise determination of instantaneous meteor altitude, velocity and deceleration. Unlike specular meteor radars (SMR), HPLA radars are diverse

  6. Dynamical Charged N-body Equilibrium in Circular Dilaton Gravity

    E-print Network

    Ryan Kerner; Robert B. Mann

    2004-10-13

    We extend the problem of $(1+1)$ circular dilaton gravity to include charged particles. We examine the two (charged) particle case in detail and find an exact equilibrium solution. We then extend this to $N-$particles and obtain a solution for this case as well. This class of solutions corresponds to $N$-particles of the same mass, spaced evenly around the circle with charges chosen so that the electric field satisfies $E^{2}=$constant. We discuss the relation of these solutions to the previous uncharged equilibrium solutions and examine the behavior when the number of particles is large. We comment on the challenges in further generalizing the solutions we obtain.

  7. Circular array of outward sloping monopoles for vehicular diversity antennas

    NASA Astrophysics Data System (ADS)

    Vaughan, Rodney G.; Andersen, J. Bach; Langhorn, M. H.

    1988-10-01

    A circular array of outward-sloping monopoles is analyzed as a diversity antenna for vehicle rooftop mounting. The monopoles are assumed to approximate minimum scattering antennas, have sinusoidal current distributions, and reside on an infinite, perfectly conducting ground plane. The envelopes of the received signals are considered Rayleigh distributed. The advantage of the array configuration is that the feedpoint spacing can be made almost arbitrarily small, even for a large number of branches. A three-element array with element lengths of 0.6 wavelengths and feedpoint spacing 0.1 wavelengths operating at 463 MHz was field-tested, and the results are in good agreement with the analysis.

  8. Cranz-Schardin camera with a large working distance for the observation of small scale high-speed flows

    NASA Astrophysics Data System (ADS)

    Skupsch, C.; Chaves, H.; Brücker, C.

    2011-08-01

    The Cranz-Schardin camera utilizes a Q-switched Nd:YAG laser and four single CCD cameras. Light pulse energy in the range of 25 mJ and pulse duration of about 5 ns is provided by the laser. The laser light is converted to incoherent light by Rhodamine-B fluorescence dye in a cuvette. The laser beam coherence is intentionally broken in order to avoid speckle. Four light fibers collect the fluorescence light and are used for illumination. Different light fiber lengths enable a delay of illumination between consecutive images. The chosen interframe time is 25 ns, corresponding to 40 × 106 frames per second. Exemplarily, the camera is applied to observe the bow shock in front of a water jet, propagating in air at supersonic speed. The initial phase of the formation of a jet structure is recorded.

  9. Cranz-Schardin camera with a large working distance for the observation of small scale high-speed flows.

    PubMed

    Skupsch, C; Chaves, H; Brücker, C

    2011-08-01

    The Cranz-Schardin camera utilizes a Q-switched Nd:YAG laser and four single CCD cameras. Light pulse energy in the range of 25 mJ and pulse duration of about 5 ns is provided by the laser. The laser light is converted to incoherent light by Rhodamine-B fluorescence dye in a cuvette. The laser beam coherence is intentionally broken in order to avoid speckle. Four light fibers collect the fluorescence light and are used for illumination. Different light fiber lengths enable a delay of illumination between consecutive images. The chosen interframe time is 25 ns, corresponding to 40 × 10(6) frames per second. Exemplarily, the camera is applied to observe the bow shock in front of a water jet, propagating in air at supersonic speed. The initial phase of the formation of a jet structure is recorded. PMID:21895249

  10. Solving the X-ray Origin Problem in Large-scale Jets with Chandra and Fermi Observations

    NASA Astrophysics Data System (ADS)

    Meyer, Eileen

    2014-09-01

    We propose deep ACIS-S observations of five kpc-scale powerful quasar jets, previously detected in short exposures 10-13 years ago, to accurately measure the X-ray flux level and spectral index for individual knots in the resolved jet. We are motivated by our recent results that in two powerful sources, 3C 273 and PKS 1136-135, the X-rays are synchrotron, rather than the widely believed IC emission off the CMB. These two models imply radically different jets and deep Chandra imaging is necessary to distinguish between them with the help of existing Fermi data. The proposed targets have been selected to cover almost 2 orders of magnitude in jet power, which allows us to evaluate the X-ray emission mechanism over a wide range of jet powers.

  11. Geologic structure generated by large-impact basin formation observed at the South Pole-Aitken basin on the Moon

    NASA Astrophysics Data System (ADS)

    Ohtake, Makiko; Uemoto, Kisara; Yokota, Yasuhiro; Morota, Tomokatsu; Yamamoto, Satoru; Nakamura, Ryosuke; Haruyama, Junichi; Iwata, Takahiro; Matsunaga, Tsuneo; Ishihara, Yoshiaki

    2014-04-01

    The South Pole-Aitken (SPA) basin is the largest clearly recognized basin on the lunar surface. Determining the composition and structure of the SPA basin interior provides critical constraints on the deep crustal and/or mantle composition of the Moon and improves our understanding of large-basin-forming impact processes. Here we present a new mineralogical map of the SPA basin interior, based on high-spatial-resolution reflectance spectra using the SELENE (Kaguya) multiband imager, which is combined with topographic data in order to interpret the geologic context. The derived mineralogical map suggests extensive distribution of ejected low-Ca pyroxene-dominant mantle material with the presence of purest anorthosite crustal materials surrounding a possible melt pool of 0.26 to 0.33 of the basin diameter near the basin center, which is significantly smaller than that suggested by the crater-scaling law. The absence of clear evidence of lower crustal material is consistent with recent impact simulation results.

  12. VERY LARGE ARRAY H I ZEEMAN OBSERVATIONS OF THE CYGNUS X REGION: DR 22 AND ON 2

    SciTech Connect

    Mayo, E. A. [Department of Biological and Physical Sciences, South Carolina State University, Orangeburg, SC 29117-0001 (United States); Troland, T. H., E-mail: emayo@scsu.edu, E-mail: troland@pa.uky.edu [Department of Physics and Astronomy, University of Kentucky, Lexington, KY40506-0055 (United States)

    2012-02-15

    We have used the Very Large Array to study the Zeeman effect in 21 cm H I absorption lines from two star-forming regions in the Cygnus X complex, DR 22 and ON 2. We measure the line-of-sight magnetic field toward these regions, finding B{sub los} = -84 {+-} 11 {mu}G toward the DR 22 H II region and B{sub los} < 50 {mu}G toward each of the two H II regions in ON 2. We interpret these results in terms of two different models. In one model, we assume that the H I Zeeman effect is a measure of magnetic fields in the associated molecular clouds. If so, then the DR 22 molecular cloud is magnetically subcritical, that is, magnetically dominated. The ON 2 molecular clouds are magnetically supercritical. In a second model, we assume that the H I Zeeman effect is a measure of magnetic fields in photon-dominated regions where the gas has been compressed (and the field amplified) by absorption of stellar radiation. We find that this second model, where the measured field strength has been affected by star formation, accounts well for the DR 22 H I Zeeman effect. This same model, however, overpredicts the magnetic field in ON 2. ON 2 may be a region where the magnetic field is energetically insignificant or where the field happens to lie nearly in the plane of the sky.

  13. Near and far field contamination modeling in a large scale enclosure: Fire Dynamics Simulator comparisons with measured observations.

    PubMed

    Ryder, Noah L; Schemel, Christopher F; Jankiewicz, Sean P

    2006-03-17

    The occurrence of a fire, no matter how small, often exposes objects to significant levels of contamination from the products of combustion. The production and dispersal of these contaminants has been an issue of relevance in the field of fire science for many years, though little work has been done to examine the contamination levels accumulated within an enclosure some time after an incident. This phenomenon is of great importance when considering the consequences associated with even low level contamination of sensitive materials, such as food, pharmaceuticals, clothing, electrical equipment, etc. Not only does such exposure present a localized hazard, but also the shipment of contaminated goods places distant recipients at risk. It is the intent of this paper to use a well-founded computational fluid dynamic (CFD) program, the Fire Dynamics Simulator (FDS), a large eddy simulation (LES) code developed by National Institute of Standards and Technology (NIST), to model smoke dispersion in order to assess the subject of air contamination and post fire surface contamination in a warehouse facility. Measured results are then compared with the results from the FDS model. Two components are examined: the production rate of contaminates and the trajectory of contaminates caused by the forced ventilation conditions. Each plays an important role in determining the extent to which the products of combustion are dispersed and the levels to which products are exposed to the contaminants throughout the enclosure. The model results indicate a good first-order approximation to the measured surface contamination levels. The proper application of the FDS model can provide a cost and time efficient means of evaluating contamination levels within a defined volume. PMID:16219419

  14. The role of inflammation, iron, and nutritional status in cancer-related anemia: results of a large, prospective, observational study

    PubMed Central

    Macciò, Antonio; Madeddu, Clelia; Gramignano, Giulia; Mulas, Carlo; Tanca, Luciana; Cherchi, Maria Cristina; Floris, Carlo; Omoto, Itaru; Barracca, Antonio; Ganz, Tomas

    2015-01-01

    Anemia in oncology patients is often considered a side effect of cancer therapy; however, it may occur before any antineoplastic treatment (cancer-related anemia). This study was aimed to evaluate the prevalence of cancer-related anemia in a large cohort of oncology patients and whether inflammation and malnutrition were predictive of its development and severity. The present study included 888 patients with cancer at different sites between May 2011 and January 2014. Patients were assessed at diagnosis before any cancer treatment. The prevalence of anemia according to the main clinical factors (tumor site, stage and performance status) was analyzed. In each patient markers of inflammation, iron metabolism, malnutrition and oxidative stress as well as the modified Glasgow prognostic score, a combined index of malnutrition and inflammation, were assessed and their role in predicting hemoglobin level was evaluated. The percentage of anemic patients was 63% with the lowest hemoglobin levels being found in the patients with most advanced cancer and compromised performance status. Hemoglobin concentration differed by tumor site and was lowest in patients with ovarian cancer. Hemoglobin concentration was inversely correlated with inflammatory markers, hepcidin, ferritin, erythropoietin and reactive oxygen species, and positively correlated with leptin, albumin, cholesterol and antioxidant enzymes. In multivariate analysis, stage, interleukin-6 and leptin were independent predictors of hemoglobin concentration. Furthermore, hemoglobin was inversely dependent on modified Glasgow Prognostic Score. In conclusion, cancer-related anemia is a multifactorial problem with immune, nutritional and metabolic components that affect its severity. Only a detailed assessment of the pathogenesis of cancer-related anemia may enable clinicians to provide safe and effective individualized treatment. PMID:25239265

  15. VERY LARGE ARRAY 1.4 GHz OBSERVATIONS OF THE GOODS-NORTH FIELD: DATA REDUCTION AND ANALYSIS

    SciTech Connect

    Morrison, Glenn E. [Institute for Astronomy, University of Hawaii, Manoa, HI 96822 (United States); Owen, Frazer N. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Dickinson, Mark [National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726 (United States); Ivison, Rob J.; Ibar, Edo [UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)

    2010-05-15

    We describe deep, new, wide-field radio continuum observations of the Great Observatories Origins Deep Survey-North field. The resulting map has a synthesized beam size of {approx}1.''7 and an rms noise level of {approx}3.9 {mu}Jy beam{sup -1} near its center and {approx}8 {mu}Jy beam{sup -1} at 15' from phase center. We have cataloged 1230 discrete radio emitters, within a 40' x 40' region, above a 5{sigma} detection threshold of {approx}20 {mu}Jy at the field center. New techniques, pioneered by Owen and Morrison, have enabled us to achieve a dynamic range of 6800:1 in a field that has significantly strong confusing sources. We compare the 1.4 GHz (20 cm) source counts with those from other published radio surveys. Our differential counts are nearly Euclidean below 100 {mu}Jy with a median source diameter of {approx}1.''2. This adds to the evidence presented by Owen and Morrison that the natural confusion limit may lie near 1 {mu}Jy. If the Euclidean slope of the counts continues down to the natural confusion limit as an extrapolation of our log N-log S, this indicates that the cutoff must be fairly sharp below 1 {mu}Jy else the cosmic microwave background temperature would increase above 2.7 K at 1.4 GHz.

  16. Inferring Large-Scale Solar Wind and Coronal Field Structure of Cycle 23 from MDI Magnetic Observation

    NASA Astrophysics Data System (ADS)

    Sun, X.; Hoeksema, J. T.; Zhao, X.; Liu, Y.; Hayashi, K.

    2013-05-01

    Using photospheric magnetic data obtained by the Michelson Doppler Imager (MDI) with a new polar field interpolation scheme, we infer the steady-state solar wind and coronal field structure throughout sunspot cycle 23 and early cycle 24 (1996-2010). A potential field extrapolation, coupled with the Wang-Sheeley-Arge (WSA) model, is retrospectively optimized for the MDI data set. The model is used to study the long-term evolution of the heliospheric current sheet (HCS), the solar wind source location, the solar wind speed (SWS), and the interplanetary magnetic field (IMF) polarity during different phases of the sunspot cycle. The results qualitatively agree well with the observations. A quantitative evaluation against in situ data gives an upper limit on the in-ecliptic modeling accuracy under the current scheme: the mean percentage error of SWS at ˜16%; the success rate of IMF polarity prediction at ˜81%. The modeling accuracy is strongly correlated to the coronal field characteristics in each solar activity phase: the SWS being most accurate during the minimum, the IMF polarity during the declining phase.

  17. Circular and Elliptic Submerged Impinging Water Jets

    NASA Astrophysics Data System (ADS)

    Claudey, Eric; Benedicto, Olivier; Ravier, Emmanuel; Gutmark, Ephraim

    1999-11-01

    Experiments and CFD have been performed to study circular and elliptic jets in a submerged water jet facility. The tests included discharge coefficient measurement to evaluate pressure losses encountered in noncircular nozzles compared to circular ones. Three-dimensional pressure mappings on the impingement surface and PIV measurement of the jet mean and turbulent velocity have been performed at different compound impingement angles relative to the impingement surface and at different stand-off distances. The objective was to investigate the effect of the non-circular geometry on the flow field and on the impact region. The tests were performed in a close loop system in which the water was pumped through the nozzles into a clear Plexiglas tank. The Reynolds numbers were typically in the range of 250000. Discharge coefficients of the elliptic nozzle was somewhat lower than that of the circular jet but spreading rate and turbulence level were higher. Pressure mapping showed that the nozzle exit geometry had an effect on the pressure distribution in the impact region and that high-pressure zones were generated at specific impact points. PIV measurements showed that for a same total exit area, the elliptic jets affected a surface area that is 8the equivalent circular. The turbulence level in the elliptic jet tripled due to the nozzle design. Results of the CFD model were in good agreement with the experimental data.

  18. Methane flux estimation of a large seep area offshore Svalbard based on visual observations and inverse hydroacoustic modeling

    NASA Astrophysics Data System (ADS)

    Veloso, Mario; Mienert, Jurgen; De Batist, Marc; Greinert, Jens

    2014-05-01

    A seep site area at west of Prins Karl Forland (Svalbard) has been monitored since 2009 in order to evaluate its changes in space and time. Hydroacoustic data captured over four years have been used to understand the dynamic of the gas release and quantify the flow rate of gas coming from the seabed. Echograms indicate that gas release occurs between 200 and 400 mbsl and show that some of the acoustic flares reach the surface. Hydroacoustic data was captured with the EK60 echosounder system which uses a split-beam technique to determine the backscattering position inside the beam. The data obtained gives accurate information of the spatial distribution of the backscattering produced by bubble release. Gas release spot positions have been obtained using a geometrical average of spatial distribution of the backscattering, produced by the bubble cloud above the seafloor. An inverse hydroacoustic method developed by Muyakshin et al (Muyakshin et al. 2010) has been used to quantify the flow rate of the gas release. The method uses as input the backscattering volume strength (SV ) of the bubble release above the seafloor, bubble size distribution (BSD) obtained from underwater video footage and bubble rising speed (BRS) values determined by models developed by different researchers (e.g., Leifer and Patro, 2002, Woolf 1993, Mendelson 1967). Gridding and interpolation of the acoustic information obtained from Sv values has been carried out, adapting the method in order to be used over a large area. Flow rate calculations of a selected area (~220 mbsl) have been carried out (using different BRS models and merged data from different years) giving values between 220 and 347 T/yr of methane assuming continuous discharge and a bubble containing 100% of CH4. Temporal variability of methane fluxes was evaluated using the 'common' insonified areas with acoustic information of gas release over the seafloor. Comparison of calculated fluxes from common areas have shown that methane release in 2009 was bigger than the rest of the years (2010, 2012 and 2013) but also has indicated big differences of fluxes during the same year, making clear big differences in a short period of time. Because our study area represents the reality of methane release in the Arctic, the comprehension of this phenomenon seems to be one of the keys to predict possible implications of the methane release over the climate change.

  19. Flow around a rotating circular cylinder with an end plate near a plane wall boundary

    NASA Astrophysics Data System (ADS)

    Panchal, Jay K.

    The objective of the present study is to investigate the characteristics of a flow around a rotating circular cylinder with and without an end plate near a wall boundary. The different cases which are taken into consideration in the current investigations were with gap ratios of 0.1d, 0.5d, 1.0d, 1.5d and 2.0d. A symmetric end plate is attached behind the rotating circular cylinder at a distance of 0.1d from the cylinder and a gap ratio of 1.5d. We performed Computational Fluid Dynamics (CFD) simulation of the flow around a rotating circular cylinder near a plane wall boundary using a CFD solver, STAR-CCM+. Free-stream velocity is kept constant at 5 m/s and the Reynolds number calculated is 3.24X104. We then studied the flow characteristics such as lift and drag generated on the circular cylinder with and without an end plate and the wake structure. We observed that the vortex suppression is increased when the gap ratio is reduced, i.e., when the circular cylinder is nearer to the plane wall boundary. As the gap ratio increases the drag force generated decreases and the lift force increases considerably. In the case of rotating circular cylinder with an end plate, the wake area has moved upwards and the lift generated has increased manifold.

  20. Strain in wet thermally oxidized square and circular mesas

    NASA Astrophysics Data System (ADS)

    Alonzo, A. C.; Cheng, X.-C.; McGill, T. C.

    2000-05-01

    In this paper, we report the observation, through optical microscopy, of drumhead-like patterns in square and circular mesas which have been wet thermally oxidized to completion. Micro-Raman spectroscopy measurements are used to show that these patterns roughly correspond to variations in strain induced in surrounding semiconductor layers by the oxidation process. In addition, the patterns have a specific orientation with respect to the crystallographic axes of the semiconductor. A crystallographic dependence of the oxidation process itself is demonstrated and used to explain the orientation of the drumhead patterns.