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Sample records for ae star mwc

  1. Locating the Accretion Footprint on a Herbig Ae Star: MWC 480

    NASA Technical Reports Server (NTRS)

    Grady, C. A.; Hamaguchi, K.; Schneider, G.; Stecklum, B.; Woodgate, B. E.; McCleary, J. E.; Williger, G. M.; Sitko, M. L.; Menard, F.; Henning, Th.; Brittain, S.; Troutmann, M.; Donehew, B.; Hines, D.; Wisniewski, J. P.; Lynch, D. K.; Russell, R. W.; Rudy, R. J.; Day, A. M.; Shenoy, A.; Wilner, D.; Silverston, M.; Bouret, J.-C.; Clampin, M.; Petre, R.

    2011-01-01

    Accretion is a fundamental process which establishes the dynamics of the protoplanetary disk and the final properties of the forming star. In solar-type stars, the star-disk coupling is determined by the magnetic field structure, which is responsible for funneling material from the disk midplane to higher latitudes on the star. Here, we use pan-chromatic data for the Herbig Ae star MWC 480 to address whether similar processes occur in intermediate-mass stars. MWC 480 has X-ray emission typical of actively accreting Herbig Ae stars, but with 5-9 x more photoelectric absorption than expected from optical and FUV data. We consider 3 sources for the absorption: the disk absorption in a wind or jet, and accretion. While we detect the disk in scattered light in are-analysis of archival HST data. the data are consistent with grazing illumination of the dust disk. We find that MWC 480's disk is stratified, geometrically thin, and is not responsible for the observed photoelectric absorption. MWC 480 drives a bipolar jet, but with a mass loss rate which is low compared to other Herbig Ae stars, where the outflow is more favorably oriented and enhanced photoelectric absorption is not seen. This excludes a jet or wind origin for the enhanced photoelectric absorption. We compare MWC 480's 0 VI emission with other Herbig Ae stars. The distribution of the emission in inclination, and lack of a correlation of profile shape and system inclination excludes equatorially-confined accretion for the FUSE Herbig Ae stars. The photoelectric absorption data further suggest that the accretion footprint on MWC 480 and other Herbig Ae stars is located at high temperate, rather than polar, latitudes. These findings support the presence of funneled accretion in MWC 480 and Herbig Ae stars, strengthening the parallel to T Tauri stars.

  2. LOCATING THE ACCRETION FOOTPRINT ON A HERBIG Ae STAR: MWC 480

    SciTech Connect

    Grady, C. A.; Hamaguchi, K.; Stecklum, B.; Woodgate, B. E.; McCleary, J. E.; Williger, G. M.; Sitko, M. L.; Hines, D.; Menard, F.; Brittain, S.; Troutmann, M.; Donehew, B.; Wisniewski, J. P.; Lynch, D. K.; Russell, R. W.; Rudy, R. J.; Day, A. N.; Shenoy, A.

    2010-08-20

    Accretion is a fundamental process which establishes the dynamics of the protoplanetary disk and the final properties of the forming star. In solar-type stars, the star-disk coupling is determined by the magnetic field structure, which is responsible for funneling material from the disk midplane to higher latitudes on the star. Here, we use pan-chromatic data for the Herbig Ae star MWC 480 to address whether similar processes occur in intermediate-mass stars. MWC 480 has X-ray emission typical of actively accreting Herbig Ae stars, but with {approx}10x more photoelectric absorption than expected from optical and FUV data. We consider three sources for the absorption: the disk, absorption in a wind or jet, and accretion. While we detect the disk in scattered light in a re-analysis of archival Hubble Space Telescope data, the data are consistent with grazing illumination of the dust disk. We find that MWC 480's disk is stratified, geometrically thin, and is not responsible for the observed photoelectric absorption. MWC 480 drives a bipolar jet, but with a mass-loss rate that is low compared to other Herbig Ae stars, where the outflow is more favorably oriented and enhanced photoelectric absorption is not seen. This excludes a jet or wind origin for the enhanced photoelectric absorption. We compare MWC 480's O VI emission with other Herbig Ae stars. The distribution of the emission in inclination, and lack of a correlation of profile shape and system inclination excludes equatorially confined accretion for the FUSE Herbig Ae stars. The photoelectric absorption data further suggest that the accretion footprint on MWC 480 and other Herbig Ae stars is located at high-temperate, rather than polar, latitudes. These findings support the presence of funneled accretion in MWC 480 and Herbig Ae stars, strengthening the parallel to T Tauri stars.

  3. Disk wind and magnetospheric accretion in emission from the Herbig Ae star MWC 480

    NASA Astrophysics Data System (ADS)

    Tambovtseva, L. V.; Grinin, V. P.; Potravnov, I. S.; Mkrtichian, D. E.

    2016-09-01

    The young Herbig Ae star MWC 480 (HD 31648) is one of the comprehensively spectroscopically studied stars in the ultraviolet, optical, and infrared spectral ranges. Using non-LTE modeling of its hydrogen spectrum, we have calculated the contribution to the hydrogen emission from such important regions of the circumstellar environment as the disk wind and the magnetosphere. We have used our own observations of the stellar spectrum performed with the 2.4-m telescope at the Thai National Observatory to quantitatively check our theoretical calculations. In addition, all of the visible and infrared spectra available in the literature have been used for a qualitative comparison. The modeling results have revealed a significant role of the magneto-centrifugal disk wind in the formation of atomic hydrogen emission. The cause of the emission line variability in the spectrum ofMWC 480 is discussed.

  4. First Keck Nulling Observations of a Young Stellar Object: Probing the Circumstellar Environment of the Herbig Ae Star MWC325

    NASA Technical Reports Server (NTRS)

    Ragland, S.; Ohnaka, K.; Hillenbrand, L.; Ridgway, S. T.; Colavita, M. M.; Akeson, R. L.; Cotton, W.; Danchi, W. C.; Hrynevich, M.; Millan-Gabet, R.; Traub, W. A.

    2012-01-01

    We present the first N-band nulling plus K- and L-band V(sup 2) observations of a young stellar object, MWC 325, taken with the 85 m baseline Keck Interferometer. The Keck nuller was designed for the study of faint dust signatures associated with debris disks, but it also has a unique capability for studying the temperature and density distribution of denser disks found around young stellar objects. Interferometric observations of MWC 325 at K, L, and N encompass a factor of five in spectral range and thus, especially when spectrally dispersed within each band, enable characterization of the structure of the inner disk regions where planets form. Fitting our observations with . geometric models such as a uniform disk or a Gaussian disk show that the apparent size increases 'monotonically with wavelength in the 2-12/Lm wavelength region, confirming the widely held assumption based on radiative transfer models, now with spatially resolved measurements over a broad wavelength range, that disks are extended with a temperature gradient. The effective size is a factor of about 1.4 and 2.2 larger in the L band and N band, respectively, compared to that in the K band. The existing interferometric measurements and the spectral energy distribution can be reproduced by a flat disk or a weakly shadowed nearly flat disk model, with only slight flaring in the outer regions of the disk, consisting of representative "sub-micron" (0.1 micron) and "micron" (2 micron) grains of a 50:50 ratio of silicate and graphite. This is in marked contrast io the disks previously found in other Herbig Ae/Be stars, suggesting a wide variety in the disk properties among Herbig Ae/Be stars.

  5. First Keck Nulling Observations of a Young Stellar Object: Probing the Circumstellar Environment of the Herbig Ae star MWC 325

    NASA Technical Reports Server (NTRS)

    Ragland, S.; Ohnaka, K.; Hillenbrand, L.; Ridgway, S. T.; Colavita, M. M.; Akeson, R. L.; Cotton, W.; Danichi, W. C.; Hrynevych, M.; Milan-Gabet, R.; Traub, W. A.

    2012-01-01

    We present the first N-band nulling plus K- and L-band V(sup 2) observations of a young stellar object, MWC325, taken with the 85 m baseline Keck Interferometer. The Keck nuller was designed for the study of faint dust signatures associated with debris disks, but it also has a unique capability for studying the temperature and density distribution of denser disks found around young stellar objects. Interferometric observations of MWC 325 at K, L and N encompass a factor of five in spectral range and thus, especially when spectrally dispersed within each band, enable characterization of the structure of the inner disk regions where planets form. Fitting our observations with geometric models such as a uniform disk or a Gaussian disk show that the apparent size increases monotonically with wavelength in the 2-12 micrometer wavelength region, confirming the widely held assumption based on radiative transfer models, now with spatially resolved measurements over broad wavelength range, that disks are extended with a temperature gradient. The effective size is a factor of about 1.3 and 2 larger in the Lband and N-band, respectively, compared to that in the K-band. The existing interferometric measurements and the spectral energy distribution can be reproduced by a flat disk or a weakly shadowed nearly flat-disk model, with only slight flaring in the outer regions of the disk, consisting of representative "sub-micron" (0.1 micron) and "micron" (2 micron) grains of a 50:50 ratio of silicate and graphite. This is marked contrast with the disks previously found in other Herbig Ae/Be stars suggesting a wide variety in the disk properties among Herbig Ae/Be stars.

  6. FIRST KECK NULLING OBSERVATIONS OF A YOUNG STELLAR OBJECT: PROBING THE CIRCUMSTELLAR ENVIRONMENT OF THE HERBIG Ae STAR MWC 325

    SciTech Connect

    Ragland, S.; Hrynevich, M.; Ohnaka, K.; Hillenbrand, L.; Ridgway, S. T.; Colavita, M. M.; Traub, W. A.; Akeson, R. L.; Millan-Gabet, R.; Cotton, W.; Danchi, W. C.

    2012-02-20

    We present the first N-band nulling plus K- and L-band V{sup 2} observations of a young stellar object, MWC 325, taken with the 85 m baseline Keck Interferometer. The Keck nuller was designed for the study of faint dust signatures associated with debris disks, but it also has a unique capability for studying the temperature and density distribution of denser disks found around young stellar objects. Interferometric observations of MWC 325 at K, L, and N encompass a factor of five in spectral range and thus, especially when spectrally dispersed within each band, enable characterization of the structure of the inner disk regions where planets form. Fitting our observations with geometric models such as a uniform disk or a Gaussian disk show that the apparent size increases monotonically with wavelength in the 2-12 {mu}m wavelength region, confirming the widely held assumption based on radiative transfer models, now with spatially resolved measurements over a broad wavelength range, that disks are extended with a temperature gradient. The effective size is a factor of about 1.4 and 2.2 larger in the L band and N band, respectively, compared to that in the K band. The existing interferometric measurements and the spectral energy distribution can be reproduced by a flat disk or a weakly shadowed nearly flat disk model, with only slight flaring in the outer regions of the disk, consisting of representative 'sub-micron' (0.1 {mu}m) and 'micron' (2 {mu}m) grains of a 50:50 ratio of silicate and graphite. This is in marked contrast to the disks previously found in other Herbig Ae/Be stars, suggesting a wide variety in the disk properties among Herbig Ae/Be stars.

  7. The immediate environments of two Herbig Be stars: MWC 1080 and HD 259431

    SciTech Connect

    Li, Dan; Mariñas, Naibí; Telesco, Charles M.

    2014-12-01

    Deep mid-infrared (10-20 μm) images with sub-arcsecond resolution were obtained for two Herbig Be stars, MWC 1080 and HD 259431, to probe their immediate environments. Our goal is to understand the origin of the diffuse nebulosities observed around these two very young objects. By analyzing our new mid-IR images and comparing them to published data at other wavelengths, we demonstrate that the well-extended emission around MWC 1080 traces neither a disk nor an envelope, but rather the surfaces of a cavity created by the outflow from MWC 1080A, the primary star of the MWC 1080 system. In the N-band images, the filamentary nebulosities trace the hourglass-shaped gas cavity wall out to ∼0.15 pc. This scenario reconciles the properties of the MWC 1080 system revealed by a wide range of observations. Our finding confirms that the environment around MWC 1080, where a small cluster is forming, is strongly affected by the outflow from the central Herbig Be star. Similarities observed between the two subjects of this study suggest that the filamentary emission around HD 259431 may also arise from a similar outflow cavity structure.

  8. Spectral transformation of the unusual variable star MWC560 to resemble a nova

    NASA Technical Reports Server (NTRS)

    Maran, Stephen P.; Michalitsianos, Andrew G.; Oliversen, Ronald J.; Sonneborn, George

    1991-01-01

    A dramatic change has occurred in the ultraviolet spectrum of the emission-line star MWC560, so that it now closely resembles the spectrum of a nova shortly after outburst. This event may signal a major mass-ejection episode such as presumably occurred in past centuries in the symbiotic star R Aquarii to produce the well-known bipolar nebula, and it may herald the emergence of a standard symbiotic-star emission-line spectrum in MWC560, corresponding to a change in evolutionary state.

  9. Far-Infrared Hydrogen Lasers in the Peculiar Star MWC 349A

    NASA Technical Reports Server (NTRS)

    Strelnitski, Vladimir; Haas, Michael R.; Smith, Howard A.; Erickson, Edwin F.; Colgan, Sean W. J.; Hollenbach, David J.

    1996-01-01

    Far-infrared hydrogen recombination lines H15(alpha)(169.4 micrometers), H12(alpha)(88.8 micrometers), and H10(alpha)(52.5 micrometers) were detected in the peculiar luminous star MWC 349A from the Kuiper Airborne Observatory. Here it is shown that at least H15(alpha) is strongly amplified, with the probable amplification factor being greater than or about equal to 10(exp 3) and a brightness temperature that is greater than or about equal to 10(exp 7) kelvin. The other two lines also show signs of amplification, although to a lesser degree. Beyond H10(alpha) the amplification apparently vanishes. The newly detected amplified lines fall into the laser wavelength domain. These lasers, as well as the previously detected hydrogen masers may originate in the photoionized circumstellar disk of MWC 349A and constrain the disk's physics and structure.

  10. Three Fundamental Periods in an 87 Year Light Curve of the Symbiotic Star MWC 560

    NASA Astrophysics Data System (ADS)

    Leibowitz, Elia M.; Formiggini, Liliana

    2015-08-01

    We construct a visual light curve of the symbiotic star MWC covering the last 87 years of its history. The data were assembled from the literature and from the AAVSO data bank. Most of the periodic components of the system brightness variation can be accounted for by the operation of three basic clocks of the periods P1 = 19,000 days, P2 = 1943 days, and P3 = 722 days. These periods can plausibly, and consistently with the observations, be attributed to three physical mechanisms in the system: the working of a solar-like magnetic dynamo cycle in the outer layers of the giant star of the system, the binary orbit cycle, and the sidereal rotation cycle of the giant star. MWC 560 is the seventh symbiotic star with historical light curves that reveal similar basic characteristics of the systems. The light curves of all these stars are well interpreted on the basis of the current understanding of the physical processes that are the major sources of the optical luminosity of these symbiotic systems.

  11. THREE FUNDAMENTAL PERIODS IN AN 87 YEAR LIGHT CURVE OF THE SYMBIOTIC STAR MWC 560

    SciTech Connect

    Leibowitz, Elia M.; Formiggini, Liliana

    2015-08-15

    We construct a visual light curve of the symbiotic star MWC covering the last 87 years of its history. The data were assembled from the literature and from the AAVSO data bank. Most of the periodic components of the system brightness variation can be accounted for by the operation of three basic clocks of the periods P1 = 19,000 days, P2 = 1943 days, and P3 = 722 days. These periods can plausibly, and consistently with the observations, be attributed to three physical mechanisms in the system: the working of a solar-like magnetic dynamo cycle in the outer layers of the giant star of the system, the binary orbit cycle, and the sidereal rotation cycle of the giant star. MWC 560 is the seventh symbiotic star with historical light curves that reveal similar basic characteristics of the systems. The light curves of all these stars are well interpreted on the basis of the current understanding of the physical processes that are the major sources of the optical luminosity of these symbiotic systems.

  12. Photometric variability of the Herbig Ae star HD 37806

    NASA Astrophysics Data System (ADS)

    Rucinski, S. M.; Zwintz, K.; Hareter, M.; Pojmański, G.; Kuschnig, R.; Matthews, J. M.; Guenther, D. B.; Moffat, A. F. J.; Sasselov, D.; Weiss, W. W.

    2010-11-01

    Context. The more massive counterparts of T Tauri stars, the Herbig Ae/Be stars, are known to vary in a complex way with no variability mechanism clearly identified. Aims: We attempt to characterize the optical variability of HD 37806 (MWC 120) on time scales ranging between minutes and several years. Methods: A continuous, one-minute resolution, 21 day-long sequence of MOST (Microvariability & Oscillations of STars) satellite observations has been analyzed using wavelet, scalegram and dispersion analysis tools. The MOST data have been augmented by sparse observations over 9 seasons from ASAS (All Sky Automated Survey), by previously non-analyzed ESO (European Southern Observatory) data partly covering 3 seasons and by archival measurements dating back half a century ago. Results: Mutually superimposed flares or accretion instabilities grow in size from about 0.0003 of the mean flux on a time scale of minutes to a peak-to-peak range of <0.05 on a time scale of a few years. The resulting variability has properties of stochastic “red” noise, whose self-similar characteristics are very similar to those observed in cataclysmic binary stars, but with much longer characteristic time scales of hours to days (rather than minutes) and with amplitudes which appear to cease growing in size on time scales of tens of years. In addition to chaotic brightness variations combined with stochastic noise, the MOST data show a weakly defined cyclic signal with a period of about 1.5 days, which may correspond to the rotation of the star. Based on data from the MOST satellite, a Canadian Space Agency mission jointly operated by Dynacon Inc., the University of Toronto Institute for Aerospace Studies and the University of British Columbia, with the assistance of the University of Vienna, and on data from the All Sky Automated Survey (ASAS) conducted by the Warsaw University Observatory, Warsaw, Poland at the Las Campanas Observatory, Chile.

  13. Evidence of the Evolved Nature of the B[e] Star MWC 137

    NASA Astrophysics Data System (ADS)

    Muratore, M. F.; Kraus, M.; Oksala, M. E.; Arias, M. L.; Cidale, L.; Borges Fernandes, M.; Liermann, A.

    2015-01-01

    The evolutionary phase of B[e] stars is difficult to establish due to the uncertainties in their fundamental parameters. For instance, possible classifications for the Galactic B[e] star MWC 137 include pre-main-sequence and post-main-sequence phases, with a large range in luminosity. Our goal is to clarify the evolutionary stage of this peculiar object, and to study the CO molecular component of its circumstellar medium. To this purpose, we modeled the CO molecular bands using high-resolution K-band spectra. We find that MWC 137 is surrounded by a detached cool (T=1900+/- 100 K) and dense (N=(3+/- 1)× {{10}21} {{cm}-2}) ring of CO gas orbiting the star with a rotational velocity, projected to the line of sight, of 84 ± 2 km s-1. We also find that the molecular gas is enriched in the isotope 13C, excluding the classification of the star as a Herbig Be. The observed isotopic abundance ratio (12C/13C = 25 ± 2) derived from our modeling is compatible with a proto-planetary nebula, main-sequence, or supergiant evolutionary phase. However, based on some observable characteristics of MWC 137, we propose that the supergiant scenario seems to be the most plausible. Hence, we suggest that MWC 137 could be in an extremely short-lived phase, evolving from a B[e] supergiant to a blue supergiant with a bipolar ring nebula. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), under program IDs GN-2011B-Q-24 and GN-2013B-Q-11.

  14. A disk asymmetry in motion around the B[e] star MWC158

    NASA Astrophysics Data System (ADS)

    Kluska, J.; Benisty, M.; Soulez, F.; Berger, J.-P.; Le Bouquin, J.-B.; Malbet, F.; Lazareff, B.; Thiébaut, E.

    2016-06-01

    Context. MWC158 is a star with the B[e] phenomenon that shows strong spectrophotometric variability (in lines and in UV and visible continuum) attributed to phases of shell ejection. The evolutionary stage of this star was never clearly determined. Previous interferometric, spectropolarimetric and spectro-interferometric studies suggest a disk morphology for its environment. Aims: We investigate the origin of the variability within the inner astronomical unit of the central star using near-infrared interferometric observations with PIONIER at the VLTI over a two-year period. Methods: We performed an image reconstruction of the circumstellar environment using the SPARCO method. We discovered that the morphology of the circumstellar environment could vary on timescales of weeks or days. We carried out a parametric fit of the data with a model consisting of a star, a disk and a bright spot that represents a brighter emission in the disk. Results: We detect strong morphological changes in the first astronomical unit around the star, that happen on a timescale of few months. We cannot account for such variability well with a binary model. Our parametric model fits the data well and allows us to extract the location of the asymmetry for different epochs. Conclusions: For the first time, we detect a morphological variability in the environment of MWC158. This variability is reproduced by a model of a disk and a bright spot. The locations of the bright spot suggest that it is located in the disk, but its precise motion is not determined. The origin of the asymmetry in the disk is complex and may be related to asymmetric shell ejections. Based on observations performed with PIONIER mounted on the ESO Very Large Telescope interferometer (programmes: 089.C-0211, 190.C-0963).

  15. AN INNER GASEOUS DISK AROUND THE HERBIG Be STAR MWC 147

    SciTech Connect

    Bagnoli, T.; Van Lieshout, R.; Waters, L. B. F. M.; Van der Plas, G.; Meerburg, P. D.; Acke, B.; Van Winckel, H.; Raskin, G.

    2010-11-20

    We present high spectral resolution, optical spectra of the Herbig Be star MWC 147, in which we spectrally resolve several emission lines, including the [O I] lines at 6300 and 6363 A. Their highly symmetric, double-peaked line profiles indicate that the emission originates in a rotating circumstellar disk. We deconvolve the Doppler-broadened [O I] emission lines to obtain a measure of emission as a function of distance from the central star. The resulting radial surface brightness profiles are in agreement with a disk structure consisting of a flat, inner, gaseous disk and a flared, outer, dust disk. The transition between these components at 2-3 AU corresponds to the estimated dust sublimation radius. The width of the double-peaked Mg II line at 4481 A suggests that the inner disk extends to at least 0.10 AU, close to the corotation radius.

  16. On the formation and evolution of the first Be star in a black hole binary MWC 656

    NASA Astrophysics Data System (ADS)

    Grudzinska, M.; Belczynski, K.; Casares, J.; de Mink, S. E.; Ziolkowski, J.; Negueruela, I.; Ribó, M.; Ribas, I.; Paredes, J. M.; Herrero, A.; Benacquista, M.

    2015-09-01

    We find that the formation of MWC 656 (the first Be binary containing a black hole) involves a common envelope phase and a supernova explosion. This result supports the idea that a rapidly rotating Be star can emerge out of a common envelope phase, which is very intriguing because this evolutionary stage is thought to be too fast to lead to significant accretion and spin up of the B star. We predict ˜10-100 of B-BH binaries to currently reside in the Galactic disc, among which around 1/3 contain a Be star, but there is only a small chance to observe a system with parameters resembling MWC 656. If MWC 656 is representative of intrinsic Galactic Be-BH binary population, it may indicate that standard evolutionary theory needs to be revised. This would pose another evolutionary problem in understanding black hole (BH) binaries, with BH X-ray novae formation issue being the prime example. Future evolution of MWC 656 with an ˜5 M⊙ BH and with an ˜13 M⊙ main-sequence companion on an ˜60 d orbit may lead to the formation of a coalescing BH-NS (neutron star) system. The estimated Advanced LIGO/Virgo detection rate of such systems is up to ˜0.2 yr-1. This empirical estimate is a lower limit as it is obtained with only one particular evolutionary scenario, the MWC 656 binary. This is only a third such estimate available (after Cyg X-1 and Cyg X-3), and it lends additional support to the existence of so far undetected BH-NS binaries.

  17. The JCMT Gould Belt Survey: evidence for radiative heating in Serpens MWC 297 and its influence on local star formation

    NASA Astrophysics Data System (ADS)

    Rumble, D.; Hatchell, J.; Gutermuth, R. A.; Kirk, H.; Buckle, J.; Beaulieu, S. F.; Berry, D. S.; Broekhoven-Fiene, H.; Currie, M. J.; Fich, M.; Jenness, T.; Johnstone, D.; Mottram, J. C.; Nutter, D.; Pattle, K.; Pineda, J. E.; Quinn, C.; Salji, C.; Tisi, S.; Walker-Smith, S.; Francesco, J. Di; Hogerheijde, M. R.; Ward-Thompson, D.; Allen, L. E.; Cieza, L. A.; Dunham, M. M.; Harvey, P. M.; Stapelfeldt, K. R.; Bastien, P.; Butner, H.; Chen, M.; Chrysostomou, A.; Coude, S.; Davis, C. J.; Drabek-Maunder, E.; Duarte-Cabral, A.; Fiege, J.; Friberg, P.; Friesen, R.; Fuller, G. A.; Graves, S.; Greaves, J.; Gregson, J.; Holland, W.; Joncas, G.; Kirk, J. M.; Knee, L. B. G.; Mairs, S.; Marsh, K.; Matthews, B. C.; Moriarty-Schieven, G.; Rawlings, J.; Richer, J.; Robertson, D.; Rosolowsky, E.; Sadavoy, S.; Thomas, H.; Tothill, N.; Viti, S.; White, G. J.; Wilson, C. D.; Wouterloot, J.; Yates, J.; Zhu, M.

    2015-04-01

    We present SCUBA-2 450 and 850 μm observations of the Serpens MWC 297 region, part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Survey of nearby star-forming regions. Simulations suggest that radiative feedback influences the star formation process and we investigate observational evidence for this by constructing temperature maps. Maps are derived from the ratio of SCUBA-2 fluxes and a two-component model of the JCMT beam for a fixed dust opacity spectral index of β = 1.8. Within 40 arcsec of the B1.5Ve Herbig star MWC 297, the submillimetre fluxes are contaminated by free-free emission with a spectral index of 1.03 ± 0.02, consistent with an ultracompact H II region and polar winds/jets. Contamination accounts for 73 ± 5 per cent and 82 ± 4 per cent of peak flux at 450 μm and 850 μm, respectively. The residual thermal disc of the star is almost undetectable at these wavelengths. Young stellar objects (YSOs) are confirmed where SCUBA-2 850 μm clumps identified by the FELLWALKER algorithm coincide with Spitzer Gould Belt Survey detections. We identify 23 objects and use Tbol to classify nine YSOs with masses 0.09 to 5.1 M⊙. We find two Class 0, one Class 0/I, three Class I and three Class II sources. The mean temperature is 15 ± 2 K for the nine YSOs and 32 ± 4 K for the 14 starless clumps. We observe a starless clump with an abnormally high mean temperature of 46 ± 2 K and conclude that it is radiatively heated by the star MWC 297. Jeans stability provides evidence that radiative heating by the star MWC 297 may be suppressing clump collapse.

  18. Mid Infrared Hydrogen Recombination Line Emission from the Maser Star MWC 349A

    NASA Technical Reports Server (NTRS)

    Smith, Howard A.; Strelnitski, V.; Miles, J. W.; Kelly, D. M.; Lacy, J. H.

    1997-01-01

    We have detected and spectrally resolved the mid-IR hydrogen recombination lines H6(alpha)(12.372 micrometers), H7(alpha)(19.062 micrometers), H7(beta)(l1.309 micrometers) and H8(gamma)(12.385 micrometers) from the star MWC349A. This object has strong hydrogen maser emission (reported in the millimeter and submillimeter hydrogen recombination lines from H36(alpha) to H21(alpha)) and laser emission (reported in the H15(alpha), H12(alpha) and H10(alpha) lines). The lasers/masers are thought to arise predominantly in a Keplerian disk around the star. The mid-IR lines do not show evident signs of lasing, and can be well modeled as arising from the strong stellar wind, with a component arising from a quasi-static atmosphere around the disk, similar to what is hypothesized for the near IR (less than or equal to 4 micrometers) recombination lines. Since populations inversions in the levels producing these mid-IR transitions are expected at densities up to approximately 10(exp 11)/cu cm, these results imply either that the disk does not contain high-density ionized gas over long enough path lengths to produce a gain approximately 1, and/or that any laser emission from such regions is small compared to the spontaneous background emission from the rest of the source as observed with a large beam. The results reinforce the interpretation of the far-IR lines as true lasers.

  19. Analysis of the variability of the luminous emission line star MWC 314

    NASA Astrophysics Data System (ADS)

    Muratorio, G.; Rossi, C.; Friedjung, M.

    2008-08-01

    Context: We investigated the surroundings of MWC 314 in the framework of the study of hot emission line star environments using the SAC method. This star is either a B[e] supergiant or a luminous blue variable and appears to be extremely luminous and massive. Aims: We determine the structure and physical conditions of the emitting region and study the possible variations. Methods: We measured the absorption and emission line radial velocities and the emission line fluxes on high-resolution spectra obtained with Aurelie at the 1.52 m OHP telescope in July 1998, with Elodie at the 1.93 m OHP telescope at various epochs, and with echelle spectrographs of the Asiago and Loiano observatories (Italy) in 2006. We used the statistical approach of the self-absorption curve method (SAC) to derive physical parameters of the line-emitting region. Results: We detected drastic variations of the photospheric absorption line radial velocities with time, while the emission line velocities appear to be stable. The Cr II, Ti II, and Fe II emission lines have a complex structure. They are double-peaked, and each of these two 60 km s-1 separated components, is composed of a narrow and a broad component, while the [Fe II] line components are narrower. The fit of the various components of the Fe II lines to a SAC curve indicates that their intensities are affected by some self absorption. We obtained a Boltzmann-type population law whose mean excitation temperature is 6500-1000+1500 K for the narrow component lower and upper levels. We obtained a higher Boltzmann-type population law of 10 500-2000+3000 K for the forbidden transition upper levels. Conclusions: From the absorption lines we confirm the binarity for MWC 314. The periodicity has nevertheless to be improved with a higher sampling frequency. Our results from the emission lines are consistent with line formation in a rotating disk around a star. The typical minimum radius of the line emitting region obtained from the SAC study

  20. Far-infrared photometry and mapping of Herbig Ae/Be stars with ISO

    NASA Astrophysics Data System (ADS)

    Ábrahám, P.; Leinert, Ch.; Burkert, A.; Henning, Th.; Lemke, D.

    2000-02-01

    Seven Herbig Ae/Be stars were observed at mid- and far-infrared wavelengths with ISOPHOT, the photometer on-board the Infrared Space Observatory. At λ{<=}25μm, where the emission mainly arises from a compact circumstellar region, the observed spectral energy distributions can be described by power-law relationships between wavelength and flux density (Fnu {~}ν-n). The exponent of the power-law changes considerably among the stars, from n~0 for MWC 1080 to n~2.3 in the case of LkHα 234, with a typical value of around 1. Interpreting the observed power-law relationships in terms of circumstellar disks, in 5 out of 6 cases relatively shallow radial temperature distributions have to be assumed (T{~}r-q where 0.37{<=}q{<=}0.53). At longer wavelengths the observed emission is spatially extended, and in some cases significant discrepancy with IRAS was found due to beam size effects. The peak of the SEDs (in Fnu ) is typically at 60-100mu m, corresponding to temperatures of around 50 K. At λ>100μm the emission observed by ISOPHOT is never dominated by the Herbig Ae/Be stars. The most likely sources of the far-infrared radiation are dust cores of about 1 arcminute in size. The dust cores are probably located in the vicinity of the stars, and may be related to the star forming process. Based on observations with ISO, an ESA project with instruments funded by ESA member states (especially the P/I countries France, Germany, the Netherlands and the United Kingdom) with participation of ISAS and NASA.

  1. Variability of Disk Emission in Pre-main-sequence and Related Stars. I. HD 31648 and HD 163296: Isolated Herbig Ae Stars Driving Herbig-Haro Flows

    NASA Technical Reports Server (NTRS)

    Sitko, Michael L.; Carpenter, William J.; Kimes, Robin L.; Wilde, J. Leon; Lynch, David K.; Russell, Ray W.; Rudy, Richard J.; Mazuk, Stephan M.; Venterini, Catherine C.; Puetter, Richard C.; Grady, Carol A.; Polomski, Elisha F.; Wisnewski, John P.; Brafford, Suellen M.; Hammel, H. B.; Perry, R. Brad

    2008-01-01

    Infrared photometry and spectroscopy covering a time span of a quarter-century are presented for HD 31648 (MWC 480) and HD 163296 (MWC 275). Both are isolated Herbig Ae stars that exhibit signs of active accretion, including driving bipolar flows with embedded Herbig-Haro (HH) objects. HD 163296 was found to be relatively quiescent photometrically in its inner disk region, with the exception of a major increase in emitted flux in a broad wavelength region centered near 3 micron in 2002. In contrast, HD 31648 has exhibited sporadic changes in the entire 3-13 micron region throughout this span of time. In both stars, the changes in the 1-5 micron flux indicate structural changes in the region of the disk near the dust sublimation zone, possibly causing its distance from the star to vary with time. Repeated thermal cycling through this region will result in the preferential survival of large grains, and an increase in the degree of crystallinity. The variability observed in these objects has important consequences for the interpretation of other types of observations. For example, source variability will compromise models based on interferometry measurements unless the interferometry observations are accompanied by nearly simultaneous photometric data.

  2. Variability of Disk Emission in Pre-Main Sequence and Related Stars. I. HD 31648 and HD 163296 - Isolated Herbig Ae Stars Driving Herbig-Haro Flows

    NASA Technical Reports Server (NTRS)

    Sitko, Michael L.; Carpenter, William J.; Kimes, Robin L.; Lynch, David K.; Russell, Ray W.; Rudy, Richard J.; Mazuk, Stephan M.; Venturini, Catherine C.; Puetter, Richard C.; Grady, Carol A.; Polomski, Elisha F.; Wisnewski, John P.; Brafford, Suellen M.; Hammel, H. B.; Perry, Raleigh B.

    2007-01-01

    Infrared photometry and spectroscopy covering a time span of a quarter century are presented for HD 31648 (MWC 480) and HD 163296 (MWC 275). Both are isolated Herbig Ae stars that exhibit signs of active accretion, including driving bipolar flows with embedded Herbig-Haro (HH) objects. HD 163296 was found to be relatively quiescent photometrically in its inner disk region, with the exception of a major increase in emitted flux in a broad wavelength region centered near 3 pm in 2002. In contrast, HD 31648 has exhibited sporadic changes in the entire 3-13 pm region throughout this span of time. In both stars the changes in the 1-5 pm flux indicate structural changes in the region of the disk near the dust sublimation zone, possibly causing its distance from the star to vary with time. Repeated thermal cycling through this region will result in the preferential survival of large grains, and an increase in the degree of crystallinity. The variability observed in these objects has important consequences for the interpretation of other types of observations. For example, source variability will compromise models based on interferometry measurements unless the interferometry observations are accompanied by nearly-simultaneous photometric data.

  3. Mid-IR Spectra Herbig Ae/Be Stars

    NASA Technical Reports Server (NTRS)

    Wooden, Diane; Witteborn, Fred C. (Technical Monitor)

    1997-01-01

    Herbig Ae/Be stars are intermediate mass pre-main sequence stars, the higher mass analogues to the T Tauri stars. Because of their higher mass, they are expected form more rapidly than the T Tauri stars. Whether the Herbig Ae/Be stars accrete only from collapsing infalling envelopes or whether accrete through geometrically flattened viscous accretion disks is of current debate. When the Herbig Ae/Be stars reach the main sequence they form a class called Vega-like stars which are known from their IR excesses to have debris disks, such as the famous beta Pictoris. The evolutionary scenario between the pre-main sequence Herbig Ae/Be stars and the main sequence Vega-like stars is not yet revealed and it bears on the possibility of the presence of Habitable Zone planets around the A stars. Photometric studies of Herbig Ae/Be stars have revealed that most are variable in the optical, and a subset of stars show non-periodic drops of about 2 magnitudes. These drops in visible light are accompanied by changes in their colors: at first the starlight becomes reddened, and then it becomes bluer, the polarization goes from less than 0.1 % to roughly 1% during these minima. The theory postulated by V. Grinnin is that large cometary bodies on highly eccentric orbits occult the star on their way to being sublimed, for systems that are viewed edge-on. This theory is one of several controversial theories about the nature of Herbig Ae/Be stars. A 5 year mid-IR spectrophotometric monitoring campaign was begun by Wooden and Butner in 1992 to look for correlations between the variations in visible photometry and mid-IR dust emission features. Generally the approximately 20 stars that have been observed by the NASA Ames HIFOGS spectrometer have been steady at 10 microns. There are a handful, however, that have shown variable mid-IR spectra, with 2 showing variations in both the continuum and features anti-correlated with visual photometry, and 3 showing variations in the emission

  4. On the binarity of Herbig Ae/Be stars

    NASA Astrophysics Data System (ADS)

    Baines, Deborah; Oudmaijer, René D.; Porter, John M.; Pozzo, Monica

    2006-04-01

    We present high-resolution spectro-astrometry of a sample of 28 Herbig Ae/Be and three F-type pre-main-sequence stars. The spectro-astrometry, which is essentially the study of unresolved features in long-slit spectra, is shown from both empirical and simulated data to be capable of detecting binary companions that are fainter by up to 6mag at separations larger than ~0.1arcsec. The nine targets that were previously known to be binary are all detected. In addition, we report the discovery of six new binaries and present five further possible binaries. The resulting binary fraction is 68 +/- 11 per cent. This overall binary fraction is the largest reported for any observed sample of Herbig Ae/Be stars, presumably because of the exquisite sensitivity of spectro-astrometry for detecting binary systems. The data hint that the binary frequency of the Herbig Be stars is larger than that of the Herbig Ae stars. The Appendix presents model simulations to assess the capabilities of spectro-astrometry and reinforces the empirical findings. Most spectro-astrometric signatures in this sample of Herbig Ae/Be stars can be explained by the presence of a binary system. Two objects, HD 87643 and Z CMa, display evidence for asymmetric outflows. Finally, the position angles of the binary systems have been compared with available orientations of the circumprimary disc and these appear to be coplanar. The alignment between the circumprimary discs and the binary systems strongly suggests that the formation of binaries with intermediate-mass primaries is due to fragmentation as the alternative, stellar capture, does not naturally predict aligned discs. The alignment extends to the most massive B-type stars in our sample. This leads us to conclude that formation mechanisms that do result in massive stars, but predict random angles between the binaries and the circumprimary discs, such as stellar collisions, are also ruled out for the same reason.

  5. The Disk and Environment of Herbig Ae Star HD 100453

    NASA Astrophysics Data System (ADS)

    Collins, Karen; Grady, C.; Wisniewski, J. P.; Hamaguchi, K.; van Boekel, R.; Brittain, S.; Carmona, A.; Williger, G.; van den Ancker, M.; Sitko, M.; Carpenter, W. J.; Woodgate, B.; Henning, T.; Petre, R.

    2007-05-01

    We present a multi-wavelength examination of the inner disk and environment of the near-ZAMS Herbig Ae star HD 100453. Chandra ACIS-S imagery shows that the Herbig Ae star has Lx=2.6x1029 erg s-1, with Lx/Lbol and a pulse height spectrum similar to β Pic Moving Group early F stars. In addition to the previously noted deficit of warm dust, the inner disk contains little molecular gas either in CO or H2. The disk also lacks the conspicuous Fe II emission and continuum seen in FUV spectra of actively accreting Herbig Ae stars. Our FUSE data suggest an accretion rate below 1x10-9 solar masses per year, while the absence of jet activity in HST ACS imagery suggests a mass loss rate below 3.5x10-11 solar masses per year. The radius of the disk wall inferred by modeling of the IR SED is sufficiently large to preclude photoevaporation of the inner disk as the sole mechanism for disk clearing, suggesting that there may be an additional body in the inner disk. The Chandra data exclude this body being a star of any mass. KC is supported by a Kentucky Space Grant Consortium Fellowship under NASA National Space Grant College and Fellowship Program Grant NNG05GH07H.

  6. HARPS spectropolarimetry of Herbig Ae/Be stars

    NASA Astrophysics Data System (ADS)

    Hubrig, S.; Ilyin, I.; Schöller, M.; Lo Curto, G.

    2013-12-01

    Our knowledge of the presence and the strength of magnetic fields in intermediate-mass pre-main-sequence stars remains very poor. We present new magnetic field measurements in six Herbig Ae/Be stars observed with HARPS in spectropolarimetric mode. We downloaded from the European Southern Observatory (ESO) archive the publically available HARPS spectra for six Herbig Ae/Be stars. Wavelength shifts between right- and left-hand side circularly polarised spectra were interpreted in terms of a longitudinal magnetic field , using the moment technique introduced by Mathys. The application of the moment technique to the HARPS spectra allowed us in addition to study the presence of the crossover effect and quadratic magnetic fields. Our search for longitudinal magnetic fields resulted in first detections of weak magnetic fields in the Herbig Ae/Be stars HD 58647 and HD 98922. Further, we confirm the previous tentative detection of a weak magnetic field in HD 104237 by Donati et al. and confirm the previous detection of a magnetic field in the Herbig Ae star HD 190073. Surprisingly, the measured longitudinal magnetic field of HD 190073, < Bz >=91±18 G at a significance level of 5σ is not in agreement with the measurement results of Alecian et al. (2013), < Bz >=-10±20 G, who applied the LSD method to exactly the same data. No crossover effect was detected for any star in the sample. Only for HD 98922 the crossover effect was found to be close to 3σ with a measured value of -4228±1443 km s-1 G. A quadratic magnetic field of the order of 10 kG was detected in HD 98922, and of ˜3.5 kG in HD 104237. Based on data obtained from the ESO Science Archive Facility under requests MSCHOELLER 51301, 51324, 36608-36611.

  7. The (BETA) Pictoris Phenomenon Among Herbig Ae/Be Stars

    NASA Technical Reports Server (NTRS)

    Grady, C. A.; Perez, M. R.; Talavera, A.; Bjorkman, K. S.; deWinter, D.; The, P.-S.; Molster, F. J.; vandenAncker, M. E.; Sitko, M. L.; Morrison, N. D.; Beaver, M. L.; McCollum, B.; Castelaz, M. W.

    1996-01-01

    We present a survey of high dispersion UV and optical spectra of Herbig Ae/Be (HAeBe) and related stars. We find accreting, circumstellar gas over the velocity range +100 to +400 km/s, and absorption profiles similar to those seen toward Beta Pic, in 36% of the 33 HAeBe stars with IUE data as well as in 3 non-emission B stars. We also find evidence of accretion in 7 HAeBe stars with optical data only. Line profile variability appears ubiquitous. As a group, the stars with accreting gas signatures have higher v sin i than the stars with outflowing material, and tend to exhibit large amplitude (greater than or equal to 1(sup m)) optical light variations. All of the program stars with polarimetric variations that are anti-correlated with the optical light, previously interpreted as the signature of a dust disk viewed close to equator-on, also show spectral signatures of accreting gas. These data imply that accretion activity in HAeBe stars is preferentially observed when the line of sight transits the circumstellar dust disk. Our data imply that the spectroscopic signatures of accreting circumstellar material seen in Beta Pic are not unique to that object, but instead are consistent with interpretation of Beta Pic as a comparatively young A star with its associated circumstellar disk.

  8. Herbig Ae/Be stars - Intermediate-mass stars surrounded by massive circumstellar accretion disks

    NASA Technical Reports Server (NTRS)

    Hillenbrand, Lynne A.; Strom, Stephen E.; Vrba, Frederick J.; Keene, Jocelyn

    1992-01-01

    The proposition that Herbig Ae/Be stars are young intermediate mass stars surrounded by optically thick accretion disks is explored. From a study of 47 such objects, a subset of 30 stars is identified whose spectral energy distributions can be interpreted convincingly in terms of pre-main sequence stars surrounded by massive optically thick circumstellar accretion disks. Constraints on the physical properties of the disks, such as size, mass, accretion rate, lifetime, and radial structure are derived from the photometric data.

  9. ACCRETION VARIABILITY OF HERBIG Ae/Be STARS OBSERVED BY X-SHOOTER HD 31648 AND HD 163296

    SciTech Connect

    Mendigutía, I.; Brittain, S.; Eiroa, C.; Meeus, G.; Montesinos, B.; Mora, A.; Muzerolle, J.; Oudmaijer, R. D.; Rigliaco, E.

    2013-10-10

    This work presents X-Shooter/Very Large Telescope spectra of the prototypical, isolated Herbig Ae stars HD 31648 (MWC 480) and HD 163296 over five epochs separated by timescales ranging from days to months. Each spectrum spans over a wide wavelength range covering from 310 to 2475 nm. We have monitored the continuum excess in the Balmer region of the spectra and the luminosity of 12 ultraviolet, optical, and near-infrared spectral lines that are commonly used as accretion tracers for T Tauri stars. The observed strengths of the Balmer excesses have been reproduced from a magnetospheric accretion shock model, providing a mean mass accretion rate of 1.11 × 10{sup –7} and 4.50 × 10{sup –7} M{sub ☉} yr{sup –1} for HD 31648 and HD 163296, respectively. Accretion rate variations are observed, being more pronounced for HD 31648 (up to 0.5 dex). However, from the comparison with previous results it is found that the accretion rate of HD 163296 has increased by more than 1 dex, on a timescale of ∼15 yr. Averaged accretion luminosities derived from the Balmer excess are consistent with the ones inferred from the empirical calibrations with the emission line luminosities, indicating that those can be extrapolated to HAe stars. In spite of that, the accretion rate variations do not generally coincide with those estimated from the line luminosities, suggesting that the empirical calibrations are not useful to accurately quantify accretion rate variability.

  10. Optical Mass Flow Diagnostics in Herbig Ae/Be Stars

    NASA Astrophysics Data System (ADS)

    Cauley, P. Wilson; Johns-Krull, Christopher M.

    2015-09-01

    We examine a broad range of mass flow diagnostics in a large sample of Herbig Ae/Be stars (HAEBES) using high resolution optical spectra. The Hβ and He i 5876 Å lines show the highest incidence of P Cygni (30%) and inverse P Cygni (14%) morphologies, respectively. The Fe ii 4924 Å line also shows a large incidence of P Cygni profiles (11%). We find support for many of the conclusions reached in a study based on the analysis of the He i λ10830 line in a large sample of HAEBES. Namely, HAEBES exhibit smaller fractions of both blueshifted absorption (i.e., mass outflow) and redshifted absorption (i.e., mass infall or accretion) than their lower mass cousins, the classical T Tauri stars (CTTSs). In particular, the optical data supports the conclusion that HAEBES displaying redshifted absorption, in general, show maximum redshifted absorption velocities that are smaller fractions of their stellar escape velocities than is found for CTTSs. This suggests that HAEBE accretion flows are originating deeper in the gravitational potentials of their stars than in CTTS systems. In addition, we find a lack of inner disk wind signatures in the blueshifted absorption objects; only stellar wind signatures are clearly observed. These findings, along with the lack of detected magnetic fields around HAEBES, support the idea that large magnetospheres are not prevalent around HAEBES and that accretion flows are instead mediated by significantly smaller magnetospheres with relatively smaller truncation radii (e.g., 1-2 R*). Redshifted absorption is much more common around Herbig Ae stars than Be stars, suggesting that Herbig Be stars may accrete via a boundary layer rather than along magnetic field lines.

  11. Laser guide star adaptive optics imaging polarimetry of Herbig Ae/Be stars.

    PubMed

    Perrin, Marshall D; Graham, James R; Kalas, Paul; Lloyd, James P; Max, Claire E; Gavel, Donald T; Pennington, Deanna M; Gates, Elinor L

    2004-02-27

    We have used laser guide star adaptive optics and a near-infrared dual-channel imaging polarimeter to observe light scattered in the circumstellar environment of Herbig Ae/Be stars on scales of 100 to 300 astronomical units. We revealed a strongly polarized, biconical nebula 10 arc seconds (6000 astronomical units) in diameter around the star LkHalpha 198 and also observed a polarized jet-like feature associated with the deeply embedded source LkHalpha 198-IR. The star LkHalpha 233 presents a narrow, unpolarized dark lane consistent with an optically thick circumstellar disk blocking our direct view of the star. These data show that the lower-mass T Tauri and intermediate mass Herbig Ae/Be stars share a common evolutionary sequence.

  12. The Herbig Ae Star HD 163296 in X-Rays

    NASA Technical Reports Server (NTRS)

    Swartz, Douglas A.; Drake, Jeremy J.; Elsner, Ronald F.; Ghosh, Kajal K.; Grady, Carol A.; Wassell, Edward

    2004-01-01

    Chandra X-ray imaging spectroscopy of the nearby Herbig Ae star HD 163296 at 100 AU angular resolution is reported. A point-like, soft (kT approximately 0.5 approximately kev), emission-line source is detected at the location of the star with an X-ray luminosity of 4.0e29 erg/s. In addition, faint emission along the direction of a previously-detected Ly-alpha-emitting jet and Herbig-Haro outflow may be present. The relatively low luminosity, lack of a hard spectral component, and absence of strong X-ray variability in HD 163296 can be explained as originating from optically-thin shock-heated gas accreting onto the stellar surface along magnetic field lines. This would require a (dipole) magnetic field strength at the surface of HD 163296 of at least approximately 100 approximately G and perhaps as high as several kG.

  13. CYANIDE PHOTOCHEMISTRY AND NITROGEN FRACTIONATION IN THE MWC 480 DISK

    SciTech Connect

    Guzmán, V. V.; Öberg, K. I.; Loomis, R.; Qi, C.

    2015-11-20

    HCN is a commonly observed molecule in Solar System bodies and in interstellar environments. Its abundance with respect to CN is a proposed tracer of UV exposure. HCN is also frequently used to probe the thermal history of objects, by measuring its degree of nitrogen fractionation. To address the utility of HCN as a probe of disks, we present Atacama Large (sub-) Millimeter Array observations of CN, HCN, H{sup 13}CN, and HC{sup 15}N toward the protoplanetary disk around Herbig Ae star MWC 480, and of CN and HCN toward the disk around T Tauri star DM Tau. Emission from all molecules is clearly detected and spatially resolved, including the first detection of HC{sup 15}N in a disk. Toward MWC 480, CN emission extends radially more than 1″ exterior to the observed cut-off of HCN emission. Quantitative modeling further reveals very different radial abundance profiles for CN and HCN, with best-fit outer cut-off radii of >300 AU and 110 ± 10 AU, respectively. This result is in agreement with model predictions of efficient HCN photodissociation into CN in the outer-part of the disk where the vertical gas and dust column densities are low. No such difference in CN and HCN emission profiles are observed toward DM Tau, suggestive of different photochemical structures in Herbig Ae and T Tauri disks. We use the HCN isotopologue data toward the MWC 480 disk to provide the first measurement of the {sup 14}N/{sup 15}N ratio in a disk. We find a low disk averaged {sup 14}N/{sup 15}N ratio of 200 ± 100, comparable to what is observed in cloud cores and comets, demonstrating interstellar inheritance and/or efficient nitrogen fractionation in this disk.

  14. Sodium Laser Guide Star Adaptive Optics Imaging Polarimetry of Herbig Ae/Be Stars

    SciTech Connect

    Perrin, M D; Graham, J R; Lloyd, J P; Kalas, P; Gates, E L; Gavel, D T; Pennington, D M; Max, C E

    2004-01-08

    The future of high-resolution ground-based optical and infrared astronomy requires the successful implementation of laser guide star adaptive optics systems. We present the first science results from the Lick Observatory sodium beacon laser guide star system. By coupling this system to a near-infrared (J;H;Ks bands) dual-channel imaging polarimeter, we achieve very high sensitivity to light scattered in the circumstellar enviroment of Herbig Ae/Be stars on scales of 100-300 AU. Observations of LkH{alpha} 198 reveal a highly polarized, biconical nebula 10 arcseconds in diameter (6000 AU) . We also observe a polarized jet-like feature associated with the deeply embedded source LkH{alpha} 198-IR. The star LkH{alpha} 233 presents a narrow, unpolarized dark lane dividing its characteristic butterfly-shaped polarized reflection nebulosity. This linear structure is oriented perpendicular to an optical jet and bipolar cavity and is consistent with the presence of an optically thick circumstellar disk blocking our direct view of the star. These data suggest that the evolutionary picture developed for the lower-mass T Tauri stars is also relevant to the Herbig Ae/Be stars and demonstrate the ability of laser guide star adaptive optics systems to obtain scientific results competitive with natural guide star adaptive optics or space-based telescopes.

  15. Molecular emission lines in Herbig Ae/Be stars

    NASA Astrophysics Data System (ADS)

    Giannini, T.; Lorenzetti, D.; Tommasi, E.; Nisini, B.; de Benedettini, M.; Barlow, M. J.; Clegg, P. E.; Cohen, M.; Liseau, R.; Molinari, S.; Palla, F.; Pezzuto, S.; Saraceno, P.; Smith, H. A.; Spinoglio, L.; Strafella, F.; White, G. J.

    1999-03-01

    We present the first ISO-LWS observations of the molecular FIR lines in 3 out of a sample of 11 Herbig Ae/Be stars (HAEBE), namely IRAS12496-7650, RCrA and LkHα234. High-J pure rotational CO lines (from Jup = 14 to Jup = 19) have been observed in all the spectra, while two (at 79 μm and 84 μm) and three OH lines (at 71, 79 and 84 μm) have been detected in LkHα234 and RCrA, respectively. For all the sources the molecular emission has been consistently fitted with a Large Velocity Gradient (LVG) model and results as originated in a warm (T >= 200 K) and dense (nH2 >= 105 cm-3) gas. By comparing the observed cooling ratios with models predictions, we find that the FUV radiation is the most probable responsible for line excitation. Shock mechanism contributions can be reasonably ruled out, especially because of the absence in the spectra of any water vapour line, in contrast with the predictions on the molecular emission coming from warm shocked

  16. MEASURING THE STELLAR ACCRETION RATES OF HERBIG Ae/Be STARS

    SciTech Connect

    Donehew, Brian; Brittain, Sean E-mail: sbritt@clemson.edu

    2011-02-15

    The accretion rate of young stars is a fundamental characteristic of these systems. While accretion onto T Tauri stars has been studied extensively, little work has been done on measuring the accretion rate of their intermediate-mass analogs, the Herbig Ae/Be stars. Measuring the stellar accretion rate of Herbig Ae/Bes is not straightforward both because of the dearth of metal absorption lines available for veiling measurements and the intrinsic brightness of Herbig Ae/Be stars at ultraviolet wavelengths where the brightness of the accretion shock peaks. Alternative approaches to measuring the accretion rate of young stars by measuring the luminosity of proxies such as the Br {gamma} emission line have not been calibrated. A promising approach is the measurement of the veiling of the Balmer discontinuity. We present measurements of this veiling as well as the luminosity of Br {gamma}. We show that the relationship between the luminosity of Br {gamma} and the stellar accretion rate for classical T Tauri stars is consistent with Herbig Ae stars but not Herbig Be stars. We discuss the implications of this finding for understanding the interaction of the star and disk for Herbig Ae/Be stars.

  17. The excess infrared emission of Herbig Ae/Be stars - Disks or envelopes?

    NASA Technical Reports Server (NTRS)

    Hartmann, Lee; Kenyon, Scott J.; Calvet, Nuria

    1993-01-01

    It is suggested that the near-IR emission in many Herbig Ae/Be stars arises in surrounding dusty envelopes, rather than circumstellar disks. It is shown that disks around Ae/Be stars are likely to remain optically thick at the required accretion rates. It is proposed that the IR excesses of many Ae/Be stars originate in surrounding dust nebulae instead of circumstellar disks. It is suggested that the near-IR emission of the envelope is enhanced by the same processes that produce anomalous strong continuum emission at temperatures of about 1000 K in reflection nebulae surrounding hot stars. This near-IR emission could be due to small grains transiently heated by UV photons. The dust envelopes could be associated with the primary star or a nearby companion star. Some Ae/Be stars show evidence for the 3.3-6.3-micron emission features seen in reflection nebulae around hot stars, which lends further support to this suggestion.

  18. Deciphering the X-ray Emission of the Nearest Herbig Ae Star

    NASA Technical Reports Server (NTRS)

    Skinner, Stephen L.

    2004-01-01

    In this research program, we obtained and analyzed an X-ray observation of the young nearby intermediate mass pre-main sequence star HD 104237 using the XMM-Newton space-based observatory. The observation was obtained on 17 Feb. 2002. This observation yielded high-quality X-ray images, spectra, and timing data which provided valuable information on the physical processes responsible for the X-ray emission. This star is a member of the group of so-called Herbig Ae/Be stars, which are young intermediate mass (approx. 2 - 4 solar masses) pre-main sequence (PMS) stars a few million years old that have not yet begun core hydrogen burning. The objective of the XMM-Newton observation was to obtain higher quality data than previously available in order to constrain possible X-ray emission mechanisms. The origin of the X-ray emission from Herbig Ae/Be stars is not yet known. These intermediate mass PMS stars lie on radiative tracks and are not expected to emit X-rays via solar-like magnetic processes, nor are their winds powerful enough to produce X-rays by radiative wind shocks as in more massive O-type stars. The emission could originate in unseen low-mass companions, or it may be intrinsic to the Herbig stars themselves if they still have primordial magnetic fields or can sustain magnetic activity via a nonsolar dynamo.

  19. COMPACT DUST CONCENTRATION IN THE MWC 758 PROTOPLANETARY DISK

    SciTech Connect

    Marino, S.; Casassus, S.; Perez, S.; Avenhaus, H.; Lyra, W.; Roman, P. E.; Wright, C. M.; Maddison, S. T.

    2015-11-01

    The formation of planetesimals requires that primordial dust grains grow from micron- to kilometer-sized bodies. Dust traps caused by gas pressure maxima have been proposed as regions where grains can concentrate and grow fast enough to form planetesimals, before radially migrating onto the star. We report new VLA Ka and Ku observations of the protoplanetary disk around the Herbig Ae/Be star MWC 758. The Ka image shows a compact emission region in the outer disk, indicating a strong concentration of big dust grains. Tracing smaller grains, archival ALMA data in band 7 continuum shows extended disk emission with an intensity maximum to the northwest of the central star, which matches the VLA clump position. The compactness of the Ka emission is expected in the context of dust trapping, as big grains are trapped more easily than smaller grains in gas pressure maxima. We develop a nonaxisymmetric parametric model inspired by a steady-state vortex solution with parameters adequately selected to reproduce the observations, including the spectral energy distribution. Finally, we compare the radio continuum with SPHERE scattered light data. The ALMA continuum spatially coincides with a spiral-like feature seen in scattered light, while the VLA clump is offset from the scattered light maximum. Moreover, the ALMA map shows a decrement that matches a region devoid of scattered polarized emission. Continuum observations at a different wavelength are necessary to conclude whether the VLA-ALMA difference is an opacity or a real dust segregation.

  20. Einstein X-ray observations of Herbig Ae/Be stars

    NASA Technical Reports Server (NTRS)

    Damiani, F.; Micela, G.; Sciortino, S.; Harnden, F. R., Jr.

    1994-01-01

    We have investigated the X-ray emission from Herbig Ae/Be stars, using the full set of Einstein Imaging Proportional Counter (IPC) observations. Of a total of 31 observed Herbig stars, 11 are confidently identified with X-ray sources, with four additonal dubious identifications. We have used maximum likelihood luminosity functions to study the distribution of X-ray luminosity, and we find that Be stars are significantly brighter in X-rays than Ae stars and that their X-ray luminosity is independent of projected rotational velocity v sin i. The X-ray emission is instead correlated with stellar bolometric luminosity and with effective temperature, and also with the kinetic luminosity of the stellar wind. These results seem to exclude a solar-like origin for the X-ray emission, a possibility suggested by the most recent models of Herbig stars' structure, and suggest an analogy with the X-ray emission of O (and early B) stars. We also observe correlations between X-ray luminosity and the emission at 2.2 microns (K band) and 25 microns, which strengthen the case for X-ray emission of Herbig stars originating in their circumstellar envelopes.

  1. Near-infrared (J, H, K) imaging of Herbig Ae/Be stars

    NASA Astrophysics Data System (ADS)

    Li, Wenbin; Evans, Neal J., II; Harvey, Paul M.; Colome, Cecilia

    1994-09-01

    Near-infrared (J, H, K) images were obtained for 16 Herbig Ae/Be stars. The primary goal was to determine the contributions by circumstellar nebulae and nearby sources to near-infrared photometry carried out with large beams. Quasi-simultaneous photometric results were obtained with small apertures. The emission toward five Herbig Ae/Be stars is extended, including all four Group II sources in our sample (Hillebrand et al. 1992); 13 objects have nearby sources (within 10 sec separation). However, the extended emission and nearby sources are too faint to affect previous photometry significantly. The surface brightness profiles of most of the nebulae can be explained by reflection nebulae which scatter the light from the central star/disk systems with single, isotropic scattering processes. The exception is Par 21, which may require emission from very small grains. The color-color diagram, making use of our new photometry, essentially agrees with the results of Lada & Adams (1992). The Group II objects in our sample tend to have extended emission more frequently than do Group I objects, supporting the suggestion of Hillebrand et al. that Group II sources are more affected by circumstellar envelopes. However, most of the near-infrared emission comes from the central (less than or = 6 sec) regions. This upper limit is still much larger than the expected size of accretion disks. Possible envelope effects could not be ruled out for most Herbig Ae/Be stars with unresolved emission. The images do not clearly favor very small, thermally emitting grains as the origin of the near-infrared emission. The problem still exists of how to explain the observed peaks near 3 sec in the spectral energy distributions of Herbig Ae/Be stars. The possible effects of envelopes and companions are addressed.

  2. Radio continuum observations of the Herbig Ae/Be stars HD 163296 and HR 5999

    NASA Technical Reports Server (NTRS)

    Brown, D. A.; Perez, M. R.; Yusef-Zadeh, F.

    1993-01-01

    Very Large Array (VLA) observations of the two bright Herbig Ae/Be stars HD 163296 and HR 5999 have been carried out at lambda 3.6 and 20 cm. We report the detection of a radio source at lambda 3.6 cm that may be associated with HD 163296. From the peak flux density of 0.39 mJy/beam area, we estimate a mass-loss rate of 1.8 x 10(exp -8) solar mass/yr if the flux is due to free-free emission in an ionized wind with spherical symmetry, assuming a terminal wind velocity of 200 km/s. HR 5999 was not detected at either wavelength. We discuss the results in terms of the stellar-driven and accretion-driven scenarios for line and wind formation in Herbig Ae/Be stars.

  3. Radio continuum observations of the Herbig Ae/Be stars HD 163296 and HR 5999

    NASA Astrophysics Data System (ADS)

    Brown, D. A.; Perez, M. R.; Yusef-Zadeh, F.

    1993-11-01

    Very Large Array (VLA) observations of the two bright Herbig Ae/Be stars HD 163296 and HR 5999 have been carried out at lambda 3.6 and 20 cm. We report the detection of a radio source at lambda 3.6 cm that may be associated with HD 163296. From the peak flux density of 0.39 mJy/beam area, we estimate a mass-loss rate of 1.8 x 10-8 solar mass/yr if the flux is due to free-free emission in an ionized wind with spherical symmetry, assuming a terminal wind velocity of 200 km/s. HR 5999 was not detected at either wavelength. We discuss the results in terms of the stellar-driven and accretion-driven scenarios for line and wind formation in Herbig Ae/Be stars.

  4. SPIRAL ARMS IN THE ASYMMETRICALLY ILLUMINATED DISK OF MWC 758 AND CONSTRAINTS ON GIANT PLANETS

    SciTech Connect

    Grady, C. A.; Muto, T.; Hashimoto, J.; Kwon, J.; Fukagawa, M.; Sai, S.; Currie, T.; Biller, B.; Thalmann, C.; Sitko, M. L.; Russell, R.; Wisniewski, J.; Dong, R.; Hornbeck, J.; Schneider, G.; Hines, D.; Martin, A. Moro; Feldt, M.; Henning, Th.; Pott, J.-U.; and others

    2013-01-01

    We present the first near-IR scattered light detection of the transitional disk associated with the Herbig Ae star MWC 758 using data obtained as part of the Strategic Exploration of Exoplanets and Disks with Subaru, and 1.1 {mu}m Hubble Space Telescope/NICMOS data. While submillimeter studies suggested there is a dust-depleted cavity with r = 0.''35, we find scattered light as close as 0.''1 (20-28 AU) from the star, with no visible cavity at H, K', or K{sub s} . We find two small-scaled spiral structures that asymmetrically shadow the outer disk. We model one of the spirals using spiral density wave theory, and derive a disk aspect ratio of h {approx} 0.18, indicating a dynamically warm disk. If the spiral pattern is excited by a perturber, we estimate its mass to be 5{sup +3} {sub -4} M{sub J} , in the range where planet filtration models predict accretion continuing onto the star. Using a combination of non-redundant aperture masking data at L' and angular differential imaging with Locally Optimized Combination of Images at K' and K{sub s} , we exclude stellar or massive brown dwarf companions within 300 mas of the Herbig Ae star, and all but planetary mass companions exterior to 0.''5. We reach 5{sigma} contrasts limiting companions to planetary masses, 3-4 M{sub J} at 1.''0 and 2 M{sub J} at 1.''55, using the COND models. Collectively, these data strengthen the case for MWC 758 already being a young planetary system.

  5. Spiral Arms in the Asymmetrically Illuminated Disk of MWC 758 and Constraints on Giant Planets

    NASA Astrophysics Data System (ADS)

    Grady, C. A.; Muto, T.; Hashimoto, J.; Fukagawa, M.; Currie, T.; Biller, B.; Thalmann, C.; Sitko, M. L.; Russell, R.; Wisniewski, J.; Dong, R.; Kwon, J.; Sai, S.; Hornbeck, J.; Schneider, G.; Hines, D.; Moro Martín, A.; Feldt, M.; Henning, Th.; Pott, J.-U.; Bonnefoy, M.; Bouwman, J.; Lacour, S.; Mueller, A.; Juhász, A.; Crida, A.; Chauvin, G.; Andrews, S.; Wilner, D.; Kraus, A.; Dahm, S.; Robitaille, T.; Jang-Condell, H.; Abe, L.; Akiyama, E.; Brandner, W.; Brandt, T.; Carson, J.; Egner, S.; Follette, K. B.; Goto, M.; Guyon, O.; Hayano, Y.; Hayashi, M.; Hayashi, S.; Hodapp, K.; Ishii, M.; Iye, M.; Janson, M.; Kandori, R.; Knapp, G.; Kudo, T.; Kusakabe, N.; Kuzuhara, M.; Mayama, S.; McElwain, M.; Matsuo, T.; Miyama, S.; Morino, J.-I.; Nishimura, T.; Pyo, T.-S.; Serabyn, G.; Suto, H.; Suzuki, R.; Takami, M.; Takato, N.; Terada, H.; Tomono, D.; Turner, E.; Watanabe, M.; Yamada, T.; Takami, H.; Usuda, T.; Tamura, M.

    2013-01-01

    We present the first near-IR scattered light detection of the transitional disk associated with the Herbig Ae star MWC 758 using data obtained as part of the Strategic Exploration of Exoplanets and Disks with Subaru, and 1.1 μm Hubble Space Telescope/NICMOS data. While submillimeter studies suggested there is a dust-depleted cavity with r = 0.''35, we find scattered light as close as 0.''1 (20-28 AU) from the star, with no visible cavity at H, K', or Ks . We find two small-scaled spiral structures that asymmetrically shadow the outer disk. We model one of the spirals using spiral density wave theory, and derive a disk aspect ratio of h ~ 0.18, indicating a dynamically warm disk. If the spiral pattern is excited by a perturber, we estimate its mass to be 5+3 - 4 MJ , in the range where planet filtration models predict accretion continuing onto the star. Using a combination of non-redundant aperture masking data at L' and angular differential imaging with Locally Optimized Combination of Images at K' and Ks , we exclude stellar or massive brown dwarf companions within 300 mas of the Herbig Ae star, and all but planetary mass companions exterior to 0.''5. We reach 5σ contrasts limiting companions to planetary masses, 3-4 MJ at 1.''0 and 2 MJ at 1.''55, using the COND models. Collectively, these data strengthen the case for MWC 758 already being a young planetary system.

  6. Spiral Arms in the Asymmetrically Illuminated Disk of MWC 758 and Constraints on Giant Planets

    NASA Technical Reports Server (NTRS)

    Grady, C. A.; Muto, T.; Hashimoto, J.; Fukagawa, M.; Currie, T.; Biller, B.; Thalmann, C.; Sitko, M. L.; Russell, R.; Wisniewski, J.; Dong, R.; Kwon, J.; Sai, S.; Hornbeck, J.; Schneider, G.; Hines, D.; Moro Martin, A.; Feldt, M.; Henning, Th.; Pott, J.-U.; Bonnefoy, M.; Bouwman, J.; Lacour, S.; McElwain, M.; Serabyn, G.

    2013-01-01

    We present the first near-IR scattered light detection of the transitional disk associated with the Herbig Ae star MWC 758 using data obtained as part of the Strategic Exploration of Exoplanets and Disks with Subaru, and 1.1 micrometer Hubble Space Telescope/NICMOS data. While submillimeter studies suggested there is a dust-depleted cavity with r = 0".35, we find scattered light as close as 0".1 (20-28 AU) from the star, with no visible cavity at H, K', or Ks . We find two small-scaled spiral structures that asymmetrically shadow the outer disk. We model one of the spirals using spiral density wave theory, and derive a disk aspect ratio of h approximately 0.18, indicating a dynamically warm disk. If the spiral pattern is excited by a perturber, we estimate its mass to be 5(exp +3)(sub -4) M(sub J), in the range where planet filtration models predict accretion continuing onto the star. Using a combination of non-redundant aperture masking data at L' and angular differential imaging with Locally Optimized Combination of Images at K' and Ks , we exclude stellar or massive brown dwarf companions within 300 mas of the Herbig Ae star, and all but planetary mass companions exterior to 0".5. We reach 5 sigma contrasts limiting companions to planetary masses, 3-4 M(sub J) at 1".0 and 2 M(sub J) at 1".55, using the COND models. Collectively, these data strengthen the case for MWC 758 already being a young planetary system.

  7. The Environment of the Optically Brightest Herbig Ae Star, HD 104237

    NASA Astrophysics Data System (ADS)

    Grady, C. A.; Woodgate, B.; Torres, Carlos A. O.; Henning, Th.; Apai, D.; Rodmann, J.; Wang, Hongchi; Stecklum, B.; Linz, H.; Williger, G. M.; Brown, A.; Wilkinson, E.; Harper, G. M.; Herczeg, G. J.; Danks, A.; Vieira, G. L.; Malumuth, E.; Collins, N. R.; Hill, R. S.

    2004-06-01

    We investigate the environment of the nearest Herbig Ae star, HD 104237, with a multiwavelength combination of optical coronagraphic, near-IR, and mid-IR imaging supported by optical, UV, and far-ultraviolet spectroscopy. We confirm the presence of T Tauri stars associated with the Herbig Ae star HD 104237, noted by Feigelson et al. We find that two of the stars within 15" of HD 104237 have IR excesses, potentially indicating the presence of circumstellar disks, in addition to the Herbig Ae star itself. We derive a new spectral type of A7.5Ve-A8Ve for HD 104237 and find log(L/Lsolar)=1.39. With these data, HD 104237 has an age of t~5 Myr, in agreement with the estimates for the other members of the association. HD 104237 is still actively accreting, with a conspicuous UV/far-UV excess seen down to 1040 Å, and is driving a bipolar microjet termed HH 669. This makes it the second, older Herbig Ae star now known to have a microjet. The presence of the microjet enables us to constrain the circumstellar disk to r<=0.6" (70 AU) with an inclination angle of i=18deg+14-11 from pole-on. The absence of a spatially extended continuum and fluorescent H2 emission near Lyα is in agreement with the prediction of shadowed disk models for the IR spectral energy distribution. With the high spatial density of disks in this group of stars, proximity, and minimal reddening, HD 104237 and its companions should serve as ideal laboratories for probing the comparative evolution of planetary systems. Based on observations made with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA Contract NAS5-26555. Based on observations made with ESO's TIMMI2 camera on La Silla, Chile, under program ID 71.C-0438. Based on observations made with the ESO VLT and the Near-IR Adaptive Optics System+Conica, under program ID 71.C-0143. Based on observations made under the ON-ESO agreement for the joint operation of the 1.52 m

  8. DIAGNOSING MASS FLOWS AROUND HERBIG Ae/Be STARS USING THE HE I λ10830 LINE

    SciTech Connect

    Cauley, P. Wilson; Johns-Krull, Christopher M. E-mail: cmj@rice.edu

    2014-12-20

    We examine He I λ10830 profile morphologies for a sample of 56 Herbig Ae/Be stars (HAEBES). We find significant differences between HAEBES and classical T-Tauri stars (CTTS) in the statistics of both blueshifted absorption (i.e., mass outflows) and redshifted absorption features (i.e., mass infall or accretion). Our results suggest that, in general, Herbig Be (HBe) stars do not accrete material from their inner disks in the same manner as CTTS, which are believed to accrete material via magnetospheric accretion, whereas Herbig Ae (HAe) stars generally show evidence for magnetospheric accretion. We find no evidence in our sample of narrow blueshifted absorption features, which are typical indicators of inner disk winds and are common in He I λ10830 profiles of CTTS. The lack of inner-disk-wind signatures in HAEBES, combined with the paucity of detected magnetic fields on these objects, suggests that accretion through large magnetospheres that truncate the disk several stellar radii above the surface is not as common for HAe and late-type HBe stars as it is for CTTS. Instead, evidence is found for smaller magnetospheres in the maximum redshifted absorption velocities in our HAEBE sample. These velocities are, on average, a smaller fraction of the system escape velocity than is found for CTTS, suggesting accretion is taking place closer to the star. Smaller magnetospheres, and evidence for boundary layer accretion in HBe stars, may explain the less common occurrence of redshifted absorption in HAEBES. Evidence is found that smaller magnetospheres may be less efficient at driving outflows compared to CTTS magnetospheres.

  9. The 2016 outburst of the unique symbiotic star MWC 560 (= V694 Mon), its long-term BVRI evolution and a marked 331 days periodicity

    NASA Astrophysics Data System (ADS)

    Munari, U.; Dallaporta, S.; Castellani, F.; Baldinelli, L.; Righetti, G. L.; Graziani, M.; Cherini, G.; Maitan, A.; Moretti, S.; Tomaselli, S.; Frigo, A.

    2016-11-01

    After 26 years from the major event of 1990, in early 2016 the puzzling symbiotic binary MWC 560 has gone into a new and even brighter outburst. We present our tight BVRCIC photometric monitoring of MWC 560 (451 independent runs distributed over 357 different nights), covering the 2005-2016 interval, and the current outburst in particoular. A stricking feature of the 2016 outburst has been the suppression of the short term chaotic variability during the rise toward maximum brightness, and its dominance afterward with an amplitude in excess of 0.5 mag. Similar to the 1990 event when the object remained around maximum brightness for ∼6 months, at the time Solar conjunction prevented further observations of the current outburst, MWC 560 was still around maximum, three months past reaching it. We place our observations into a long term contex by combining with literature data to provide a complete 1928-2016 lightcurve. Some strong periodicities are found to modulate the optical photometry of MWC 560. A period of 1860 days regulate the occourence of bright phases at BVRC bands (with exactly 5.0 cycles separating the 1990 and 2016 outbursts), while the peak brightness attained during bright phases seems to vary with a ∼9570 days cycle. A clean 331 day periodicity modulate the IC lightcurve, where the emission from the M giant dominates, with a lightcurve strongly reminiscent of an ellipsoidal distortion plus irradiation from the hot companion. Pros and cons of 1860 and 331 days as the system orbital period are reviewed, waiting for a spectroscopic radial velocity orbit of the M giant to settle the question (provided the orbit is not oriented face-on).

  10. HARPS spectropolarimetry of three sharp-lined Herbig Ae stars: New insights ⋆

    NASA Astrophysics Data System (ADS)

    Järvinen, S. P.; Carroll, T. A.; Hubrig, S.; Schöller, M.; Ilyin, I.; Korhonen, H.; Pogodin, M.; Drake, N. A.

    2015-12-01

    Aims: Recently, several arguments have been presented that favour a scenario in which the low detection rate of magnetic fields in Herbig Ae stars can be explained by the weakness of these fields and rather large measurement uncertainties. Spectropolarimetric studies involving sharp-lined Herbig Ae stars appear to be a promising approach for the detection of such weak magnetic fields. These studies offer a clear spectrum interpretation with respect to the effects of blending, local velocity fields, and chemical abundances, and allow us to identify a proper sample of spectral lines appropriate for magnetic field determination. Methods: High-resolution spectropolarimetric observations of the three sharp-lined (vsini< 15 km s-1) Herbig Ae stars HD 101412, HD 104237, and HD 190073 have been obtained in recent years with the HARPS spectrograph in polarimetric mode. We used these archival observations to investigate the behaviour of their longitudinal magnetic fields. To carry out the magnetic field measurements, we used the multi-line singular value decomposition (SVD) method for Stokes profile reconstruction. Results: We carried out a high-resolution spectropolarimetric analysis of the Herbig Ae star HD 101412 for the first time. We discovered that different line lists yield differences in both the shape of the Stokes V signatures and their field strengths. They could be interpreted in the context of the impact of the circumstellar matter and elemental abundance inhomogeneities on the measurements of the magnetic field. On the other hand, due to the small size of the Zeeman features on the first three epochs and the lack of near-IR observations, circumstellar and photospheric contributions cannot be estimated unambiguously. In the SVD Stokes V spectrum of the SB2 system HD 104237, we detect that the secondary component, which is a T Tauri star, possesses a rather strong magnetic field ⟨Bz⟩ = 129 ± 12 G, while no significant field is present in the primary

  11. High angular resolution and young stellar objects: Imaging the surroundings of MWC 158 by optical interferometry

    NASA Astrophysics Data System (ADS)

    Kluska, J.; Malbet, F.; Berger, J.-P.; Benisty, M.; Lazareff, B.; Le Bouquin, J.-B.; Pinte, C.

    2012-12-01

    In the course of our VLTI young stellar object PIONIER imaging program, we have identified a strong visibility chromatic dependency that appeared in certain sources. This effect, rising value of visibilities with decreasing wavelengths over one base, is also present in previous published and archival AMBER data. For Herbig AeBe stars, the H band is generally located at the transition between the star and the disk predominance in flux for Herbig AeBe stars. We believe that this phenomenon is responsible for the visibility rise effect. We present a method to correct the visibilities from this effect in order to allow "gray" image reconstruction software, like Mira, to be used. In parallel we probe the interest of carrying an image reconstruction in each spectral channel and then combine them to obtain the final broadband one. As an illustration we apply these imaging methods to MWC158, a (possibly Herbig) B[e] star intensively observed with PIONIER. Finally, we compare our result with a parametric model fitted onto the data.

  12. The magnetic field of the pre-main sequence Herbig Ae star HD 190073

    NASA Astrophysics Data System (ADS)

    Catala, C.; Alecian, E.; Donati, J.-F.; Wade, G. A.; Landstreet, J. D.; Böhm, T.; Bouret, J.-C.; Bagnulo, S.; Folsom, C.; Silvester, J.

    2007-01-01

    Context: The general context of this paper is the study of magnetic fields in the pre-main sequence intermediate mass Herbig Ae/Be stars. Magnetic fields are likely to play an important role in pre-main sequence evolution at these masses, in particular in controlling the gains and losses of stellar angular momentum. Aims: The particular aim of this paper is to announce the detection of a structured magnetic field in the Herbig Ae star HD 190073, and to discuss various scenarii for the geometry of the star, its environment and its magnetic field. Methods: We have used the ESPaDOnS spectropolarimeter at CFHT in 2005 and 2006 to obtain high-resolution, high signal-to-noise circular polarization spectra which demonstrate unambiguously the presence of a magnetic field in the photosphere of this star. Results: Nine circular polarization spectra were obtained, each one showing a clear Zeeman signature. This signature is suggestive of a magnetic field structured on large scales. The signature, which corresponds to a longitudinal magnetic field of 74± 10 G, does not vary detectably on a one-year timeframe, indicating either an azimuthally symmetric field, a zero inclination angle between the rotation axis and the line of sight, or a very long rotation period. The optical spectrum of HD 190073 exhibits a large number of emission lines. We discuss the formation of these emission lines in the framework of a model involving a turbulent heated region at the base of the stellar wind, possibly powered by magnetic accretion. Conclusions: .This magnetic detection contributes an important new observational discovery which will aid our understanding of stellar magnetism at intermediate masses. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

  13. Observations of the peculiar object MWC 560 in outburst

    SciTech Connect

    Michalitsianos, A.G.; Maran, S.P.; Oliversen, R.J.; Bopp, B.; Kontizas, E. Toledo, University, OH Athens, National Observatory )

    1991-04-01

    The results of ultraviolet spectroscopy, photoelectric photometry, and supplemental high-resolution H(alpha) spectroscopy of a photometric outburst of MWC 560 are discussed. Ultraviolet spectra are shown to be consistent with the ejection of an optically thick shell that produced strong absorption blends of Fe II and Cr II. The velocities reported exceed by far those previously found in symbiotic stars or recurrent novas. In addition to the variable high-velocity system of broad absorption features, a relatively stable system of Mg II, Mg I, Fe II, Cr II, and other ionic absorptions is observed. It is pointed out that the spectroscopic phenomena in MWC 560 resemble those found in XX Ophiuchi, but the velocities in the MWC 560 are an order of magnitude higher than those found in XX Oph. 30 refs.

  14. Observations of the peculiar object MWC 560 in outburst

    NASA Technical Reports Server (NTRS)

    Michalitsianos, A. G.; Maran, S. P.; Oliversen, R. J.; Bopp, B.; Kontizas, E.

    1991-01-01

    The results of ultraviolet spectroscopy, photoelectric photometry, and supplemental high-resolution H(alpha) spectroscopy of a photometric outburst of MWC 560 are discussed. Ultraviolet spectra are shown to be consistent with the ejection of an optically thick shell that produced strong absorption blends of Fe II and Cr II. The velocities reported exceed by far those previously found in symbiotic stars or recurrent novas. In addition to the variable high-velocity system of broad absorption features, a relatively stable system of Mg II, Mg I, Fe II, Cr II, and other ionic absorptions is observed. It is pointed out that the spectroscopic phenomena in MWC 560 resemble those found in XX Ophiuchi, but the velocities in the MWC 560 are an order of magnitude higher than those found in XX Oph.

  15. CO AND H{sup +}{sub 3} TOWARD MWC 1080, MWC 349, AND LkH{alpha} 101

    SciTech Connect

    Gibb, E. L.; Brittain, S. D.; Troutman, M.; Rettig, T. W.; Simon, Theodore; Kulesa, C.

    2010-06-01

    We present high-resolution, near-infrared NIRSPEC observations of the fundamental rovibrational CO and H{sup +} {sub 3} R(1,0), R(1,1) {sup u}, and Q(1,0) transitions toward three early-type young stars: MWC 1080, MWC 349, and LkH{alpha} 101. These observations were performed for the purpose of constraining the physical characteristics of the interstellar material along each line of sight. Toward MWC 1080, we detected strong CO absorption and determined a column density upper limit of 1.4 x 10{sup 14} cm{sup -2} for H{sup +} {sub 3}. We infer that there is very little diffuse material along the line of sight toward MWC 1080 and that the CO absorption is consistent with an origin in the dispersing natal cloud. We detected both cold CO and H{sup +} {sub 3} toward MWC 349, consistent with a diffuse cloud origin. Similarly, both CO and H{sup +} {sub 3} were detected toward LkH{alpha} 101. Using a recently revised value for the cosmic ray ionization rate, we conclude that the CO absorption is consistent with a dense cloud origin while the H{sup +} {sub 3} could originate in either the dense or diffuse interstellar medium. We also find no evidence for CO fractionation toward LkH{alpha} 101 as reported by Goto et al.

  16. The Mg 2 lines as diagnostic of PMS nature in Herbig Ae/Be stars

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The main objective of this program was to observe some newly discovered and previously unobserved Herbig Ae/Be (HAeBe) stars with IUE. A previous archival study suggested that there was a full range of profiles in the Mg II lines for these objects; ranging from the double peak emission to the narrow absorption lines. It has been found that by studying the IUE data of main sequence B and classical Be stars that the P Cygni profiles in the Mg II lines in HAeBe stars are truly unique and are the signature of accelerating winds in their extended circumstellar material. The arguement, for the purposes of this proposal, that the structure of the Mg II lines was a superior diagnostic of the dynamical activity and ultimately the PMS nature of these objects. This program was a follow up study of several interesting intermediate-mass stars with the goal of classifying these objects based on the shape of their MG II lines. A list of publications resulting from this research is included.

  17. A Study of Ro-vibrational OH Emission from Herbig Ae/Be Stars

    NASA Astrophysics Data System (ADS)

    Brittain, Sean D.; Najita, Joan R.; Carr, John S.; Ádámkovics, Máté; Reynolds, Nickalas

    2016-10-01

    We present a study of ro-vibrational OH and CO emission from 21 disks around Herbig Ae/Be stars. We find that the OH and CO luminosities are proportional over a wide range of stellar ultraviolet luminosities. The OH and CO line profiles are also similar, indicating that they arise from roughly the same radial region of the disk. The CO and OH emission are both correlated with the far-ultraviolet luminosity of the stars, while the polycyclic aromatic hydrocarbon (PAH) luminosity is correlated with the longer wavelength ultraviolet luminosity of the stars. Although disk flaring affects the PAH luminosity, it is not a factor in the luminosity of the OH and CO emission. These properties are consistent with models of UV-irradiated disk atmospheres. We also find that the transition disks in our sample, which have large optically thin inner regions, have lower OH and CO luminosities than non-transition disk sources with similar ultraviolet luminosities. This result, while tentative given the small sample size, is consistent with the interpretation that transition disks lack a gaseous disk close to the star.

  18. Photometric and Polarimetric Activity of the Herbig Ae Star VX Cas

    NASA Astrophysics Data System (ADS)

    Shakhovskoi, D. N.; Rostopchina, A. N.; Grinin, V. P.; Minikulov, N. Kh.

    2003-04-01

    We present the results of our simultaneous photometric and polarimetric observations of the Herbig Ae/Be star VX Cas acquired in 1987 2001. The star belongs to the UX Ori subtype of young variable stars and exhibits a rather low level of photometric activity: only six Algol-like minima with amplitudes ΔV>1m were recorded in 15 years of observations. Two of these minima, in 1998 and 2001, were the deepest in the history of the star’s photometric studies, with V amplitudes of about 2m. In each case, the dimming was accompanied by an increase in the linear polarization in agreement with the law expected for variable circumstellar extinction. The highest V polarization was about 5%. Observations of VX Cas in the deep minima revealed a turnover of the color tracks, typical of stars of this type and due to an increased contribution from radiation scattered in the circumstellar disk. We separated the observed polarization of VX Cas into interstellar (P is) and intrinsic (P in) components. Their position angles differ by approximately 60°, with P is dominating in the bright state and P in dominating during the deep minima. The competition of these two polarization components leads to changes in both the degree and position angle of the polarization during the star’s brightness variations. Generally speaking, in terms of the behavior of the brightness, color indices, and linear polarization, VX Cas is similar to other UX Ori stars studied by us earlier. A number of episodes of photometric and polarimetric activity suggest that, in their motion along highly eccentric orbits, circumstellar gas and dust clouds can enter the close vicinity of the star (and be disrupted there).

  19. A high-resolution spectropolarimetric survey of Herbig Ae/Be stars - I. Observations and measurements

    NASA Astrophysics Data System (ADS)

    Alecian, E.; Wade, G. A.; Catala, C.; Grunhut, J. H.; Landstreet, J. D.; Bagnulo, S.; Böhm, T.; Folsom, C. P.; Marsden, S.; Waite, I.

    2013-02-01

    This is the first in a series of papers in which we describe and report the analysis of a large survey of Herbig Ae/Be stars in circular spectropolarimetry. Using the ESPaDOnS and Narval high-resolution spectropolarimeters at the Canada-France-Hawaii and Bernard Lyot Telescopes, respectively, we have acquired 132 circularly polarized spectra of 70 Herbig Ae/Be stars and Herbig candidates. The large majority of these spectra are characterized by a resolving power of about 65 000, and a spectral coverage from about 3700 Å to 1 μm. The peak signal-to-noise ratio per CCD pixel ranges from below 100 (for the faintest targets) to over 1000 (for the brightest). The observations were acquired with the primary aim of searching for magnetic fields in these objects. However, our spectra are suitable for a variety of other important measurements, including rotational properties, variability, binarity, chemical abundances, circumstellar environment conditions and structure, etc. In this paper, we describe the sample selection, the observations and their reduction, and the measurements that will comprise the basis of much of our following analysis. We describe the determination of fundamental parameters for each target. We detail the least-squares deconvolution (LSD) that we have applied to each of our spectra, including the selection, editing and tuning of the LSD line masks. We describe the fitting of the LSD Stokes I profiles using a multicomponent model that yields the rotationally broadened photospheric profile (providing the projected rotational velocity and radial velocity for each observation) as well as circumstellar emission and absorption components. Finally, we diagnose the longitudinal Zeeman effect via the measured circular polarization, and report the longitudinal magnetic field and Stokes V Zeeman signature detection probability. As an appendix, we provide a detailed review of each star observed.

  20. Spectroscopic signatures of magnetospheric accretion in Herbig Ae/Be stars. I. The case of HD 101412

    NASA Astrophysics Data System (ADS)

    Schöller, M.; Pogodin, M. A.; Cahuasquí, J. A.; Drake, N. A.; Hubrig, S.; Petr-Gotzens, M. G.; Savanov, I. S.; Wolff, B.; González, J. F.; Mysore, S.; Ilyin, I.; Järvinen, S. P.; Stelzer, B.

    2016-07-01

    Context. Models of magnetically-driven accretion and outflows reproduce many observational properties of T Tauri stars. This concept is not well established for the more massive Herbig Ae/Be stars. Aims: We intend to examine the magnetospheric accretion in Herbig Ae/Be stars and search for rotational modulation using spectroscopic signatures, in this first paper concentrating on the well-studied Herbig Ae star HD 101412. Methods: We used near-infrared spectroscopic observations of the magnetic Herbig Ae star HD 101412 to test the magnetospheric character of its accretion disk/star interaction. We reduced and analyzed 30 spectra of HD 101412, acquired with the CRIRES and X-shooter spectrographs installed at the VLT (ESO, Chile). The spectroscopic analysis was based on the He iλ10 830 and Paγ lines, formed in the accretion region. Results: We found that the temporal behavior of these diagnostic lines in the near-infrared spectra of HD 101412 can be explained by rotational modulation of line profiles generated by accreting gas with a period P = 20.53d±1.68d. The discovery of this period, about half of the magnetic rotation period Pm = 42.076d previously determined from measurements of the mean longitudinal magnetic field, indicates that the accreted matter falls onto the star in regions close to the magnetic poles intersecting the line-of-sight two times during the rotation cycle. We intend to apply this method to a larger sample of Herbig Ae/Be stars. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 087.C-0124(A), 088.C-0218(A,B,C,E), 090.C-0331(A), and 092.C-0126(A).

  1. The optical counterpart of IRAS 12496 - 7650 - A highly embedded Herbig AE star

    NASA Astrophysics Data System (ADS)

    Hughes, J. D.; Hartigan, P.; Graham, J. A.; Emerson, J. P.; Marang, F.

    1991-03-01

    Optical and near-infrared observations of IRAS 12496 - 7650, an active young star and the most luminous IRAS source in the Chamaeleon II dark cloud, are reported. The object has become brighter at optical wavelengths since 1976, and has exhibited variations of more than a magnitude at K between January 1987 and May 1990. IRAS 12496 - 7650 is redder when fainter, and the amplitude of the brightness fluctuations decreases toward longer infrared wavelengths. Differing amounts of circumstellar extinction or intrinsic color variations of the source can produce most of the observed variability. Optical spectra confirm that IRAS 12496 - 7650 is an extremely active (probably Herbig Ae type) star with blueshifted forbidden lines of O I and S II and a prominent P-Cygni profile at H-alpha. The S II emission extends 3-4 arcsec on either side of the star and shows a significant velocity gradient, suggestive of a jetlike structure. The detection of outflowing material from IRAS 12496 - 7650 reinforces earlier evidence that this object is the exciting source for the HH 52 - 54 group Herbig-Haro objects. The broad spectral energy distribution suggests that IRAS 12496 - 7650 has a circumstellar disk.

  2. NuSTAR AND SWIFT Observations of the Fast Rotating Magnetized White Dwarf AE Aquarii

    NASA Technical Reports Server (NTRS)

    Kitaguchi, Takao; An, Hongjun; Beloborodov, Andrei M.; Gotthelf, Eric V.; Hayashi, Takayuki; Kaspi, Victoria M.; Rana, Vikram R.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Hailey, Charles J.; Harrison, Fiona A.; Stern, Daniel; Zhang, Will W.

    2014-01-01

    AE Aquarii is a cataclysmic variable with the fastest known rotating magnetized white dwarf (P(sub spin) = 33.08 s). Compared to many intermediate polars, AE Aquarii shows a soft X-ray spectrum with a very low luminosity (LX (is) approximately 10(exp 31) erg per second). We have analyzed overlapping observations of this system with the NuSTAR and the Swift X-ray observatories in 2012 September. We find the 0.5-30 keV spectra to be well fitted by either an optically thin thermal plasma model with three temperatures of 0.75(+0.18 / -0.45), 2.29(+0.96 / -0.82), and 9.33 (+6.07 / -2.18) keV, or an optically thin thermal plasma model with two temperatures of 1.00 (+0.34 / -0.23) and 4.64 (+1.58 / -0.84) keV plus a power-law component with photon index of 2.50 (+0.17 / -0.23). The pulse profile in the 3-20 keV band is broad and approximately sinusoidal, with a pulsed fraction of 16.6% +/- 2.3%. We do not find any evidence for a previously reported sharp feature in the pulse profile.

  3. NuStar and Swift Observations of the Fast Rotating Magnetized White Dwarf AE Aquarii

    NASA Technical Reports Server (NTRS)

    Kitaguchi, Takao; An, Hongjun; Beloborodov, Andrei M.; Gotthelf, Eric V.; Hayashi, Takayuki; Kaspi, Victoria M.; Rana, Vikram R.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Hailey, Charles J.; Harrison, Fiona A.; Stern, Daniel; Zhang, Will W.

    2014-01-01

    AE Aquarii is a cataclysmic variable with the fastest known rotating magnetized white dwarf (P(sub spin) = 33.08 s). Compared to many intermediate polars, AE Aquarii shows a soft X-ray spectrum with a very low luminosity (LX (is) approximately 10(exp 31) erg per second). We have analyzed overlapping observations of this system with the NuSTAR and the Swift X-ray observatories in 2012 September. We find the 0.5-30 keV spectra to be well fitted by either an optically thin thermal plasma model with three temperatures of 0.75(+0.18 / -0.45), 2.29(+0.96 / -0.82), and 9.33 (+6.07 / -2.18) keV, or an optically thin thermal plasma model with two temperatures of 1.00 (+0.34 / -0.23) and 4.64 (+1.58 / -0.84) keV plus a power-law component with photon index of 2.50 (+0.17 / -0.23). The pulse profile in the 3-20 keV band is broad and approximately sinusoidal, with a pulsed fraction of 16.6% +/- 2.3%. We do not find any evidence for a previously reported sharp feature in the pulse profile.

  4. The variable Herbig Ae Star HR 5999. X - Its photometric 'pulse-shaped' variability

    NASA Technical Reports Server (NTRS)

    Perez, M. R.; Webb, J. R.; The, P. S.

    1992-01-01

    We present additional photometric observations (Stromgren y filter) of the Herbig Ae Star HR 5999. This new set of data, composed of 282 data points covering April 1983 to August 1989, was used in conjunction with the 362 data points compiled by Baade and Stahl (1989). Our aim was to detect single or multiple periods in the integrated set of data spanning nearly 20 yr. Through the use of series analysis techniques, and by removing any linear component present in the raw data, we were able to detect weak peaks in the power spectra (in the order of intensity the strongest peaks are at 301 and 113 d) which were not self-evident in the phase diagrams. The overall picture of the data shows a small linear component, which is more noticeable in the new set of data, indicating that the recent maxima appear brighter. By a detailed analysis of the full light curve we were able to detect the presence of well-defined 'pulses' or bursts. Further Gaussian fits of these bursts indicated that the pulses are relatively rapid, of the order of 10 d, with some of them being closely spaced. No periodicity was found for the pulses. A possible explanation of these aperiodic outbursts is that they detect a flow of matter accompanied by magnetic field disturbances originated from the interior of the star, unlike those originating externally such as binary perturbations, which tend to be periodic.

  5. H2 emission from disks around Herbig Ae and T Tauri stars

    NASA Astrophysics Data System (ADS)

    Thi, W. F.; van Dishoeck, E. F.; Blake, G. A.; van Zadelhoff, G. J.; Hogerheijde, M. R.; Mannings, V.; Sargent, A. I.; Becklin, E. E.; Horn, J.; Zuckerman, B.; Koerner, D.; Mundy, L. G.; Waters, L. B. F. M.; Wesselius, P. R.; van den Ancker, M. E.; Natta, A.; Waelkens, C.; Malfait, K.

    1999-03-01

    We present the initial results of a deep ISO-SWS survey for the low J pure rotational emission lines of H2 toward a number of Herbig Ae and T Tauri stars. The objects are selected to be as isolated as possible from molecular clouds, with a spectral energy distribution characteristic of a circumstellar disk. For most of them the presence of a disk has been established directly by millimeter interferometry. The S(1) line is detected in most sources with a peak flux of 0.3-1 Jy. The S(0) line is definitely seen in 2 objects: GG Tau. The observations suggest the presence of ``warm'' gas at Tkin~ 100 K with a mass of a few % of the total gas + dust mass, derived assuming a gas-to-dust ratio of 100:1. The S(1) peak flux does not show a strong correlation with spectral type of the central star or continuum flux at 1.3 millimeter. Possible origins for the warm gas seen in H2 are discussed, and comparisons with model calculations are made.

  6. The evidence for clumpy accretion in the Herbig Ae star HR 5999

    NASA Technical Reports Server (NTRS)

    Perez, M. R.; Grady, C. A.; The, P. S.

    1993-01-01

    Analysis of IUE high- and low-dispersion spectra of the young Herbig Ae star HR 5999 (HD 144668) covering 1978-1992 revealed dramatic changes in the Mg II h and k (2795.5, 2802.7 A) emission profiles, changes in the column density and distribution in radial velocity of accreting gas, and flux in the Ly(alpha), O I, and C IV emission lines, which are correlated with the UV excess luminosity. Variability in the spectral type inferred from the UV spectral energy distribution, ranging from A5 IV-III in high state to A7 III in the low state, was also observed. The trend of earlier inferred spectral type with decreasing wavelength and with increasing UV continuum flux has previously been noted as a signature of accretion disks in lower mass pre-main sequence stars (PMS) and in systems undergoing FU Orionis-type outbursts. Our data represent the first detection of similar phenomena in an intermediate mass (M greater than or equal to 2 solar mass) PMS star. Recent IUE spectra show gas accreting toward the star with velocities as high as plus 300 km/s, much as is seen toward beta Pic, and suggest that we also view this system through the debris disk. The absence of UV lines with the rotational broadening expected given the optical data (A7 IV, V sini=180 plus or minus 20 km/s for this system) also suggests that most of the UV light originates in the disk, even in the low continuum state. The dramatic variability in the column density of accreting gas, is consistent with clumpy accretion, such as has been observed toward beta Pic, is a hallmark of accretion onto young stars, and is not restricted to the clearing phase, since detectable amounts of accretion are present for stars with 0.5 Myr less than t(sub age) less than 2.8 Myr. The implications for models of beta Pic and similar systems are briefly discussed.

  7. Relating jet structure to photometric variability: the Herbig Ae star HD 163296

    NASA Astrophysics Data System (ADS)

    Ellerbroek, L. E.; Podio, L.; Dougados, C.; Cabrit, S.; Sitko, M. L.; Sana, H.; Kaper, L.; de Koter, A.; Klaassen, P. D.; Mulders, G. D.; Mendigutía, I.; Grady, C. A.; Grankin, K.; van Winckel, H.; Bacciotti, F.; Russell, R. W.; Lynch, D. K.; Hammel, H. B.; Beerman, L. C.; Day, A. N.; Huelsman, D. M.; Werren, C.; Henden, A.; Grindlay, J.

    2014-03-01

    Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the outflow history. We present the first optical to near-infrared (NIR) spectra of the jet from the Herbig Ae star HD 163296, obtained with VLT/X-shooter. We determine the physical conditions in the knots and also their kinematic "launch epochs". Knots are formed simultaneously on either side of the disk, with a regular interval of ~16 yr. The velocity dispersion versus jet velocity and the energy input are comparable between both lobes. However, the mass-loss rate, velocity,and shock conditions are asymmetric. We find Ṁjet/Ṁacc ~ 0.01-0.1, which is consistent with magneto-centrifugal jet launching models. No evidence of any dust is found in the high-velocity jet, suggesting a launch region within the sublimation radius (<0.5 au). The jet inclination measured from proper motions and radial velocities confirms that it is perpendicular to the disk. A tentative relation is found between the structure of the jet and the photometric variability of the central source. Episodes of NIR brightening were previously detected and attributed to a dusty disk wind. We report for the first time significant optical fadings lasting from a few days up to a year, coinciding with the NIR brightenings. These are very likely caused by dust lifted high above the disk plane, and this supports the disk wind scenario. The disk wind is launched at a larger radius than the high-velocity atomic jet, although their outflow variability may have a common origin. No significant relation between outflow and accretion variability could be established. Our findings confirm that this source undergoes periodic ejection events, which may be coupled with dust ejections above the disk plane. Based on observations

  8. Investigating the Origin of Hot Gas Lines in Herbig Ae/Be Stars

    NASA Astrophysics Data System (ADS)

    Cauley, P. Wilson; Johns-Krull, Christopher M.

    2016-07-01

    We analyze high-resolution UV spectra of a small sample of Herbig Ae/Be stars (HAEBESs) in order to explore the origin of the T ˜ 105 K gas in these stars. The C iv λ λ1548, 1550 line luminosities are compared to nonsimultaneous accretion rate estimates for the objects showing C iv emission. We show that the correlation between L C iv and \\dot{M} previously established for classical T Tauri stars (CTTSs) seems to extend into the HAEBE mass regime, although the large spread in literature \\dot{M} and A V values makes the actual relationship highly uncertain. With the exception of DX Cha, we find no evidence for hot, optically thick winds in our HAEBE sample. All other objects showing clear doublet emission in C iv can be well described by a two-component (i.e., a single component for each doublet member) or four-component (i.e., two components for each doublet member) Gaussian emission line fit. The morphologies and peak-flux velocities of these lines suggest that they are formed in weak, optically thin stellar winds and not in an accretion flow, as is the case for the hot lines observed in CTTSs. The lack of strong outflow signatures and lack of evidence for line formation in accretion flows are consistent with the conclusion presented in our recent optical and He i λ10830 studies that the immediate circumstellar environments of HAEBESs, in general, are not scaled-up analogs of the immediate environments around CTTSs. The conclusions presented here for hot gas lines around HAEBESs should be verified with a larger sample of objects.

  9. High-Contrast NIR Polarization Imaging of MWC480

    NASA Technical Reports Server (NTRS)

    McElwain, M. W.; Kusakabe, N.; Hashimoto, J.; Kudo, T.; Kandori, R.; Miyama, S.; Morino, J.-I.; Suto, H.; Suzuki, R.; Tamura, M.; Grady, C. A.; Sitko, M. L.; Werren, C.; Day, A. N.; Beerman, C.; Iye, M.; Lynch, D. K.; Russell, R. W.; Brafford, S. M.

    2012-01-01

    One of the key predictions of modeling from the IR excess of Herbig Ae stars is that for protoplanetary disks, where significant grain growth and settling has occurred, the dust disk has flattened to the point that it can be partially or largely shadowed by the innermost material at or near the dust sublimation radius. When the self-shadowing has already started, the outer disk is expected to be detected in scattered light only in the exceptional cases that the scale height of the dust disk at the sublimation radius is smaller than usual. High-contrast imaging combined with the IR spectral energy distribution allow us to measure the degree of flattening of the disk, as well as to determine the properties of the outer disk. We present polarimetric differential imaging in H band obtained with Subaru/HiCIAO of one such system, MWC 480. The HiCIAO data were obtained at a historic minimum of the NIR excess. The disk is detected in scattered light from 0".2-1"0 (27.4-137 AU). Together with the marginal detection of the disk from 1998 February 24 by HST / NICMOS, our data constrain the opening half angle for the disk to lie between 1.3 <= Theta <=2.2 deg. When compared with similar measures in CO for the gas disk from the literature, the dust disk subtends only approx 30% of the gas disk scale height (H/R approx 0. 03). Such a dust disk is a factor of 5-7 flatter than transitional disks, which have structural signatures that giant planets have formed.

  10. The Asymmetrical Wind of the Candidate Luminous Blue Variable MWC 314

    NASA Technical Reports Server (NTRS)

    Wisniewski, John P.; Babler, Brian L.; Bjorkman, Karen S.; Kurchakov, Anatoly V.; Meade,Marilyn R.; Miroshnichenko, Anatoly S.

    2006-01-01

    We present the results of long-term spectropolarimetric and spectroscopic monitoring of MWC 314, a candidate Luminous Blue Variable star. We detect the first evidence of H alpha variability in MWC 314, and find no apparent periodicity in this emission. The total R-band polarization is observed to vary between 2.21% and 3.00% at a position angle consistently around approximately 0 degrees, indicating the presence of a time-variable intrinsic polarization component, hence an asymmetrical circumstellar envelope. We find suggestive evidence that MWC 314's intrinsic polarization exhibits a wavelength-independent magnitude varying between 0.09% and 0.58% at a wavelength-independent position angle covering all four quadrants of the Stokes Q-U plane. Electron scattering off of density clumps in MWC 314's wind is considered as the probable mechanism responsible for these variations.

  11. ISO-LWS observations of Herbig Ae/Be stars. II. Molecular lines

    NASA Astrophysics Data System (ADS)

    Giannini, T.; Lorenzetti, D.; Tommasi, E.; Nisini, B.; Benedettini, M.; Pezzuto, S.; Strafella, F.; Barlow, M.; Clegg, P. E.; Cohen, M.; di Giorgio, A. M.; Liseau, R.; Molinari, S.; Palla, F.; Saraceno, P.; Smith, H. A.; Spinoglio, L.; White, G. J.

    1999-06-01

    We present the first ISO-LWS observations of the molecular FIR lines in 3 out of a sample of 11 Herbig Ae/Be stars (HAEBE), namely IRAS12496-7650, RCrA and LkHα 234. High-J rotational CO lines (from Jup = 14 to Jup = 19) have been observed in all the spectra, while two (at 79 mu m and 84 mu m) and three OH lines (at 71 mu m, 79 mu m and 84 mu m) were detected in LkHα 234 and RCrA respectively. For all sources the molecular emission has been consistently fitted with a Large Velocity Gradient (LVG) model and it results originated in a warm (T ga 200 K) and dense (nH_2 >~ 10(5) cm(-3) ) gas located in very compact regions having diameters of few hundreds of AU. These three sources are those with the highest density among the stars of the sample; this suggests that the molecular emission arises in regions showing density peaks. By comparing the observed cooling ratios with model predictions, we find that the FUV radiation from the central source (or from a more embedded companion) is the most likely responsible for the line excitation. At least for the sources where OH has been observed, the contribution of shocks to the line emission can be reasonably ruled out because of the absence in the spectra of any water vapour lines, in contrast with the predictions for molecular emission coming from warm shocked environments. Based on observations with ISO, an ESA project with instruments funded by ESA Member States and with the participation of ISAS and NASA}

  12. Photometric activity of UX orionis stars and related objects in the near infrared and optical: CO Ori, RR Tau, UX Ori, and VV Ser

    NASA Astrophysics Data System (ADS)

    Shenavrin, V. I.; Rostopchina-Shakhovskaya, A. N.; Grinin, V. P.; Demidova, T. V.; Shakhovskoi, D. N.; Belan, S. P.

    2016-08-01

    This paper continues a study of the photometric activity of UX Ori stars in the optical and near-infrared ( JHKLM bands) initiated in 2000. For comparison, the list of program stars contains two Herbig Ae stars that are photometrically quiet in the optical: MWC480 andHD179218. Fadings ofUXOri stars in the optical ( V band) due to sporadic increases of the circumstellar extinction are also observed in the infrared (IR), but with decreasing amplitude. Two stars, RR Tau and UX Ori, displayed photometric events when V -band fadings were accompanied by an increase in IR fluxes. Among the two Herbig Ae stars that are photometrically quiet in the optical, MWC 480 proved to be fairly active in the IR. Unlike the UX Ori stars, the variation amplitude of MWC 480 increases from the J band to the M band. In the course of the observations, no deep fadings in the IR bands were detected. This indicates that eclipses of the program stars have a local nature, and are due to extinction variations in the innermost regions of the circumstellar disks. The results presented testify to an important role of the alignment of the circumstellar disks relative to the direction towards the observer in determining the observed IR variability of young stars.

  13. A Photometric Catalog of Herbig AE/BE Stars and Discussion of the Nature and Cause of the Variations of UX Orionis Stars

    NASA Astrophysics Data System (ADS)

    Herbst, W.; Shevchenko, V. S.

    1999-08-01

    UBVR photometric monitoring of Herbig Ae/Be stars and some related objects has been carried out at Maidanak Observatory in Uzbekistan since 1983. More than 71,000 observations of about 230 stars have been obtained and are made available for anonymous ftp. Virtually all Herbig Ae/Be stars observed are irregular variables (called ``UXors'' after UX Ori), but there is a wide range of amplitudes from barely detectable to more than 4 mag in V. Our data confirm the results of previous studies, which indicate that large-amplitude variability is confined to stars with spectral types later than B8. The distribution of variability ranges is quite similar to what is seen in classical T Tauri stars. A careful search has failed to reveal any evidence for periodic variations up to 30 days, which can be interpreted as rotation periods. This is a clear distinction between the light variations of low-mass and high-mass pre-main-sequence stars. The Herbig Ae/Be stars evidently do not possess either the large, stable cool spots or persistent hot spots associated with strong surface magnetic fields and magnetically funneled accretion in classical T Tauri stars. A wide variety of shapes, timescales, and amplitudes exists, but the most common behavior is well illustrated by the light curve of LkHα 234. There are two principal components: (1) irregular variations on timescales of days around a mean brightness level that changes on a much longer timescale (typically years), sometimes in a quasi-cyclic fashion, and (2) occasional episodes of deep minima, occurring at irregular intervals but more frequently near the low points of the brightness cycles. Our data suggest that many T Tauri stars of K0 and earlier spectral type share the same variability characteristics as Herbig Ae/Be stars and should be regarded as UXors. Two FU Orionis stars (``FUors''), FU Ori and V1515 Cyg, also have recent light curves that are similar, in some respects, to UXors. The most developed model to account for

  14. A spectroscopic survey of Herbig Ae/Be stars with X-shooter - I. Stellar parameters and accretion rates

    NASA Astrophysics Data System (ADS)

    Fairlamb, J. R.; Oudmaijer, R. D.; Mendigutía, I.; Ilee, J. D.; van den Ancker, M. E.

    2015-10-01

    Herbig Ae/Be stars (HAeBes) span a key mass range that links low- and high-mass stars, and thus provide an ideal window from which to explore their formation. This paper presents Very Large Telescope/X-shooter spectra of 91 HAeBes, the largest spectroscopic study of HAeBe accretion to date. A homogeneous approach to determining stellar parameters is undertaken for the majority of the sample. Measurements of the ultraviolet are modelled within the context of magnetospheric accretion, allowing a direct determination of mass accretion rates. Multiple correlations are observed across the sample between accretion and stellar properties: the youngest and often most massive stars are the strongest accretors, and there is an almost 1:1 relationship between the accretion luminosity and stellar luminosity. Despite these overall trends of increased accretion rates in HAeBes when compared to classical T Tauri stars, we also find noticeable differences in correlations when considering the Herbig Ae and Herbig Be subsets. This, combined with the difficulty in applying a magnetospheric accretion model to some of the Herbig Be stars, could suggest that another form of accretion may be occurring within Herbig Be mass range.

  15. Observations of Herbig Ae/Be Stars with Herschel/PACS: The Atomic and Molecular Contents of Their Protoplanetary Discs

    NASA Technical Reports Server (NTRS)

    Meeus, G.; Montesinos, B.; Mendigutia, I.; Kamp, I.; Thi, W. F.; Eiroa, C.; Grady, C. A.; Mathews, G.; Sandell, G.; Martin-Zaidi, C.; Brittain, S.; Dent, W. R. F.; Howard, C.; Menard, F.; Pinte, C.; Roberge, A.; Vandenbussche, B.; Williams, J. P.

    2012-01-01

    We observed a sample of 20 representative Herbig Ae/Be stars and 5 A-type debris discs with PACS onboard Herschel, as part of the GAS in Protoplanetary Systems (GASPS) project. The observations were done in spectroscopic mode, and cover the far-infrared lines of [OI], [CII], CO, CH+, H20, and OH. We have a [OI]63 micro/ detection rate of 100% for the Herbig Ae/Be and 0% for the debris discs. The [OI] 145 micron line is only detected in 25% and CO J = 18-17 in 45% (and fewer cases for higher J transitions) of the Herbig Ae/Be stars, while for [CII] 157 micron, we often find spatially variable background contamination. We show the first detection of water in a Herbig Ae disc, HD 163296, which has a settled disc. Hydroxyl is detected as well in this disc. First seen in HD 100546, CH+ emission is now detected for the second time in a Herbig Ae star, HD 97048. We report fluxes for each line and use the observations as line diagnostics of the gas properties. Furthermore, we look for correlations between the strength of the emission lines and either the stellar or disc parameters, such as stellar luminosity, ultraviolet and X-ray flux. accretion rate, polycyclic aromatic hydrocarbon (PAH) band strength, and flaring. We find that the stellar ultraviolet flux is the dominant excitation mechanism of [OI] 63 micron, with the highest line fluxes being found in objects with a large amount of flaring and among the largest PAH strengths. Neither the amount of accretion nor the X-ray luminosity has an influence on the line strength. We find correlations between the line flux of [OI]63 micron and [OI] 145 micron, CO J = IS-17 and [OI] 6300 A, and between the continuum flux at 63 micron and at 1.3 mm, while we find weak correlations between the line flux. of [OI] 63 micron and the PAH luminosity, the line flux of CO J = 3-2, the continuum flux at 63 pm, the stellar effective temperature, and the Br-gamma luminosity. Finally, we use a combination of the [OI] 63 micron and C(12)O J

  16. UV spectral variability in the Herbig Ae star HR 5999. 11: The accretion interpretation

    NASA Technical Reports Server (NTRS)

    Perez, M. R.; Grady, C. A.; The, P. S.

    1993-01-01

    We report recent IUE high- and low-dispersion observations with the IUE long wavelength camera (LWP) and short wavelength camera (SWP) of the Herbig Ae star HR 5999. We have found a dramatic change in the structure of the Mg II h and k lines (2795.5, 2802.7 A) along with some continuum flux excesses especially at the short end of the SWP camera. LWP high dispersion observations of HR 5999 obtained between 1979 and 1990, at times of comparatively low UV continuum fluxes, exhibit P Cygni type m profiles in the Mg II resonance doublet. In contrast, observations made from September 1990 through March 16-18, 1992, with high W continuum fluxes, present Mg II lines with reverse P Cygni profiles indicative of some active episodic accretion. Accreting gas can also be detected in the additional red wings of the various Fe II and Mn II absorption lines, with velocities up to +300-350 km/s (September 1990). By September 10, 1992 the Mg II profile had returned to the type III P Cygni profile similar to those from earlier spectra. The correlation between the presence of large column densities of accreting gas and the continuum light variations supports suggestions by several authors that HR 5999 is surrounded by an optically thick, viscously heated accretion disk. Detection of accreting gas in the line of sight to HR 5999 permits us to place constraints on our viewing geometry for this system. A discussion is included comparing the spectral and physical similarities between HR 5999 and the more evolved proto-planetary candidate system, beta Pictoris.

  17. Undergraduate Observations of Separation and Position Angle of Double Stars ARY 6 AD and ARY 6 AE at Manzanita Observatory

    NASA Astrophysics Data System (ADS)

    Hoffert, Michael J.; Weise, Eric; Clow, Jenna; Hirzel, Jacquelyn; Leeder, Brett; Molyneux, Scott; Scutti, Nicholas; Spartalis, Sarah; Tokuhara, Corey

    2014-05-01

    Six beginning astronomy students, part of an undergraduate stellar astronomy course, one advanced undergraduate student assistant, and a professor measured the position angles and separations of Washington Double Stars (WDS) 05460 + 2119 (also known as ARY 6 AD and ARY 6 AE). The measurements were made at the Manzanita Observatory (116° 20'42" W, 32° 44' 5" N) of the Tierra Astronomical Institute on 10 Blackwood Rd. in Boulevard, California (www.youtube.com/watch?v=BHVdcMGBGDU), at an elevation of 4,500 ft. A Celestron 11" HD Edge telescope was used to measure the position angles and separations of ARY 6 AD and ARY 6 AE. The averages of our measurements are as follows: separation AD: trial 1 124.1 arcseconds and trial 2 124.5 arcseconds. The average of separation for AE: trial 1 73.3 arcseconds and trial 2 73.8 arcseconds. The averages of position angle for AD: trial 1 159.9 degrees and trial 2 161.3 degrees. The averages of position angle for AE: trial 1 232.6 degrees and trial 2 233.7 degrees.

  18. THE PARSEC-SCALE ENVIRONMENT AND THE EVOLUTIONARY STATUS OF MWC 349A

    SciTech Connect

    Strelnitski, Vladimir; Armstrong, Peter; Lagergren, Krister; Walker, Gary; Bieging, John H.; Hora, Joseph; Smith, Howard A. E-mail: bailyhill14@gmail.com E-mail: jbieging@as.arizona.edu E-mail: hsmith@cfa.harvard.edu

    2013-11-10

    We report on a study of the ∼10' (∼5 pc in projection) environs of the peculiar, high-luminosity emission-line star MWC 349A in the IR, radio, and visible domains. Besides the recently discovered X-shaped, arcmin-scale IR nebula centered on MWC 349A ({sup X} nebula{sup )}, with the kinematic age of ∼10{sup 4} yr, we identify several young objects pointing toward an ongoing process of active star formation in this region and estimate some physical parameters of the newly discovered objects. The radiation of the X nebula is due to a geometrically and optically thin dust front heated to T{sub d} ≈ 60-70 K by the radiation of the central star. The bipolar dust front probably results from the interaction of a powerful stellar wind with the circumstellar disk. One of the related objects is an elongated, cold molecular cloud, ∼1 pc in size, adjacent to MWC 349A in projection and having the same radial velocity (V{sub LSR} ≈ +9 km s{sup –1}). The proximity of the molecular cloud may indicate that MWC 349A was born locally rather than being a runaway object ejected from the core of Cyg OB2 several Myr ago. If it is still associated with its natal cloud, MWC 349A may be a rare example of the observable pre-main-sequence stage of a ∼30 M{sub ☉} star. If the association with the molecular cloud is an effect of projection, however, MWC 349A may already be an evolved star, even if it was born locally. We discuss future observations that may shed more light on the evolutionary status of this unique object.

  19. The Parsec-scale Environment and the Evolutionary Status of MWC 349A

    NASA Astrophysics Data System (ADS)

    Strelnitski, Vladimir; Bieging, John H.; Hora, Joseph; Smith, Howard A.; Armstrong, Peter; Lagergren, Krister; Walker, Gary

    2013-11-01

    We report on a study of the ~10' (~5 pc in projection) environs of the peculiar, high-luminosity emission-line star MWC 349A in the IR, radio, and visible domains. Besides the recently discovered X-shaped, arcmin-scale IR nebula centered on MWC 349A ("X nebula"), with the kinematic age of ~104 yr, we identify several young objects pointing toward an ongoing process of active star formation in this region and estimate some physical parameters of the newly discovered objects. The radiation of the X nebula is due to a geometrically and optically thin dust front heated to Td ≈ 60-70 K by the radiation of the central star. The bipolar dust front probably results from the interaction of a powerful stellar wind with the circumstellar disk. One of the related objects is an elongated, cold molecular cloud, ~1 pc in size, adjacent to MWC 349A in projection and having the same radial velocity (V LSR ≈ +9 km s-1). The proximity of the molecular cloud may indicate that MWC 349A was born locally rather than being a runaway object ejected from the core of Cyg OB2 several Myr ago. If it is still associated with its natal cloud, MWC 349A may be a rare example of the observable pre-main-sequence stage of a ~30 M ⊙ star. If the association with the molecular cloud is an effect of projection, however, MWC 349A may already be an evolved star, even if it was born locally. We discuss future observations that may shed more light on the evolutionary status of this unique object.

  20. Line Identifications and Preliminary Synthesis of High-resolution Infrared Spectra of CP and Herbig Ae Stars

    NASA Astrophysics Data System (ADS)

    Cowley, Charles R.; Castelli, F.; Hubrig, S.; Wolff, B.; Elkin, V.

    2012-01-01

    We report on surveys of infrared spectra of chemically peculiar and Herbig Ae stars based on CRIRES (Kaufl, et al. SPIE, 5492, 1218 2004). We discuss the magnetic CP stars Gamma Equ and HD 154708, and multiple-phase observations of the Herbig Ae star HD 101412. The Be star HR 4537 and HgMn HR 6620 were also examined. The primary emphasis of the present work is on line identifications primarily in four regions, 1065-1091, 1084-1109,1550-1587, and 2276-2313nm (with order gaps). Observations were reduced with recipes available from the ESO CRIRES data reduction pipeline. Wavelength calibration is determined from daytime ThAr arc lamp exposures. Generally speaking, this is not rich in atomic lines. The strongest features are the Paschen line P6 (1093.81nm), and He I (108.30nm). The latter shows phase variations indicative of a more complex magnetic field than that of a pure dipole. No individual molecular lines were found in these early stars, though CO emission from circumstellar material is likely present in HR 4537 and HD 101412. We used atomic line lists from Kurucz's site (kurucz.harvard.edu) and VALD (http://vald.astro.univie.ac.at/ cf. Kupka et al. 1999, A&AS, 138, 119), supplemented by Outred (J. Phys. Chem. Ref. Data 7, 1, 1978). The following spectra were identified in Gamma Equ: C I, Si I, Ca I, Mg I, II, Cr I, Fe I, Sr II, and Ce III (1584.75nm). The Ap star spectra show broad Zeeman patterns compatible with published models and field strengths. Synthetic calculations used SYNTHE and SYNTHMAG (Piskunov N. E., 1999, in Astrophys. Space Sci. Library Vol. 243, Solar polarization. Kluwer, p 515). The γ Equ model is from Heiter et al. (2002, A&A, 392, 619). and the line list from VALD.

  1. HIGH-RESOLUTION MID-INFRARED IMAGING OF THE CIRCUMSTELLAR DISKS OF HERBIG Ae/Be STARS

    SciTech Connect

    Marinas, N.; Telesco, C. M.; Packham, C.; Fisher, R. S.

    2011-08-20

    We have imaged the circumstellar environments of 17 Herbig Ae/Be stars at 12 and 18 {mu}m using MICHELLE on Gemini North and T-ReCS on Gemini South. Our sample contained eight Group I sources, those having large rising near- to far-infrared (IR) fluxes, and nine Group II sources, those having more modest mid-IR fluxes relative to their near-IR flux (in the classification of Meeus et al.). We have resolved extended emission from all Group I sources in our target list. The majority of these sources have radially symmetric mid-IR emission extending from a radius of 10 AU to hundreds of AU. Only one of the nine Group II sources is resolved at the FWHM level, with another two Group II sources resolved at fainter levels. Models by Dullemond et al. explain the observed spectral energy distribution of Group II sources using self-shadowed cold disks. If this is the case for all the Group II sources, we do not expect to detect extended emission with this study, since the IR emission measured should arise from a region only a few AU in size, which is smaller than our resolution. The fact that we do resolve some of the Group II sources implies that their disks are not completely flat, and might represent an intermediate stage. We also find that none of the more massive (>3 M{sub sun}) Herbig Ae/Be stars in our sample belongs to Group I, which may point to a relationship between stellar mass and circumstellar dust evolution. Disks around more massive stars might evolve faster so that stars are surrounded by a more evolved flat disk by the time they become optically visible, or they might follow a different evolutionary path altogether.

  2. NEAR-CONTEMPORANEOUS OPTICAL SPECTROSCOPIC AND INFRARED PHOTOMETRIC OBSERVATIONS OF CANDIDATE HERBIG Ae/Be STARS IN THE MAGELLANIC CLOUDS

    SciTech Connect

    Rush, Bradley W.; Bjorkman, Karen S.; Wisniewski, John P. E-mail: Karen.Bjorkman@utoledo.edu

    2011-08-15

    We present near-IR (J, H, Ks) photometry for 27 of the 28 candidate Herbig Ae/Be stars in the Small and Large Magellanic Clouds (SMC and LMC) identified via the EROS1 and EROS2 surveys as well as near-contemporaneous optical (H{alpha}) spectroscopy for 21 of these 28 candidates. Our observations extend previous efforts to determine the evolutionary status of these objects. We compare the IR brightness and colors of a subset of our sample with archival ground-based IR data and find evidence of statistically significant photometric differences for EROS LMC HAeBe candidates (ELHC) 5, 7, 12, 18, and 21 in one or more filters. In all cases, these near-IR photometric variations exhibit a gray color as compared to earlier epoch data. The {approx}1 mag IR brightening and minimal change in the H{alpha} emission strength we observe in ELHC 7 is consistent with previous claims that it is a UX Ori type HAe/Be star, which is occasionally obscured by dust clouds. We also detect a {approx}1 mag IR brightening of ELHC 12, but find little evidence of a similar large-scale change in its H{alpha} line strength, suggesting that its behavior could also be caused by a UX Ori-like event. The {approx}0.5 mag IR variability we observe for ELHC 21, which also exhibited little evidence of a change in its H{alpha} emission strength, could conceivably be caused by a major recent enhancement in the density of the inner disk region of a classical Be star. We also report the first near-IR photometry for two EROS SMC HAeBe Candidates (ESHC) stars and the first H{alpha} spectroscopy for one ELHC and five ESHC stars. Although H{alpha} emission is detected in all of these new observations, they do not exhibit a strong near-IR excess. It is therefore possible that many of these objects may be classical Be stars rather than Herbig Ae/Be stars.

  3. An ongoing, record-breaking outburst of the unique symbiotic binary MWC 560 = V694 Mon

    NASA Astrophysics Data System (ADS)

    Munari, U.; Righetti, G. L.; Dallaporta, S.; Moretti, S.; Graziani, M.; Valisa, P.

    2016-02-01

    The unique symbiotic binary MWC 560 = V694 Mon is on a steep rise in brightness, about to surpass the record level attained during the last - and much studied - outburst of 1990 (Tomov et al. 1990, Nature 346, 637), the brightest event in the historical light-curve of the object (Leibowitz and Formiggini 2014, AJ 150, 52). At that time MWC 560 attracted special interest by showing deep and broad absorptions, blue-shifted by 6000 km/s and completely detached from corresponding emission lines, as if originating in discrete blobs, ejected from the central star and rapidly accelerated to large velocities.

  4. Are MWC349 A and B a Physical Binary?

    NASA Astrophysics Data System (ADS)

    Drew, Patrick; Strelnitski, Vladimir; Smith, Howard Alan; Dave Latham Jessica Mink and the TRES instrument Team, Maria Mitchell Association

    2016-01-01

    The age and evolutionary status of the only known hydrogen recombination line maser and laser star MWC349A, "A", is unknown because its spectrum has no absorption features for classification. Star A has an optical B0III companion 2.4 arcsec away, MWC349B. Previous studies suggest A & B are either gravitationally bound, and therefore both a few Myr old, or not bound and A is possibly an observable 30 Msolar star in its pre-main sequence stage. We attempt to solve the controversy by measuring the difference of radial velocities between A and B using observations from the 1.5m Tillinghast telescope and the TRES spectrometer at the Whipple Observatory. With an assumed distance of 1.2 kpc and masses of ~30 Msolar, the radial velocities cannot differ by >3 km/s for the stars to be gravitationally bound. We find a radial velocity with respect to the local standard of rest of 42 ± 18 km/s for B, and compare it with the known radial velocity of 8 ± 2 km/s for A giving a difference of 34 ± 20 km/s - much greater than 3 km/s. We conclude that A and B are not gravitationally bound, although light contamination from star A in B's spectrum makes this result somewhat inconclusive. If confirmed, however, the known spectral type of B will not determine the age of star A and star A may be an observable 30 Msolar star in its pre-main sequence stage. We gratefully acknowledge support from Dave Latham, Jessica Mink and the TRES instrument team. This project was supported in part by the NSF REU grant AST-1358980 and by the Maria Mitchell Association.

  5. Interpreting the spectral behavior of MWC 314

    NASA Astrophysics Data System (ADS)

    Frasca, A.; Miroshnichenko, A. S.; Rossi, C.; Friedjung, M.; Marilli, E.; Muratorio, G.; Busà, I.

    2016-01-01

    Context. MWC 314 is one of the most luminous stars in the Milky Way. Its fundamental parameters are similar to those of luminous blue variables (LBVs), although no large photometric variations have been recorded. Moreover, it shows no evidence of either a dust shell or a relevant spectral variability. Aims: The main purpose of this work is to clarify the origin of the radial velocity and line profile variations exhibited by absorption and emission lines. Methods: We analyzed the radial velocity (RV) variations displayed by the absorption lines from the star's atmosphere using high-resolution optical spectra and fitting the RV curve with an eccentric orbit model. We also studied the RV and profile variations of some permitted and forbidden emission lines of metallic ions with a simple geometric model. The behavior of the Balmer and He i lines has also been investigated. Results: Fourier analysis applied to the RV of the absorption lines clearly shows a 60-day periodicity. A dense coverage of the RV curve allowed us to derive accurate orbital parameters. The RV of the Fe ii emission lines varies in the same way, but with a smaller amplitude. Additionally, the intensity ratio of the blue/red peaks of these emission lines correlates with the RV variations. The first three members of the Balmer series as well as [N ii] lines display a nearly constant RV and no profile variations in phase with the orbital motion instead. The He i λ5876 Å line shows a strongly variable profile with broad and blue-shifted absorption components that reach velocities of ≤-1000 km s-1 in some specific orbital phases. Conclusions: Our data and analysis provide strong evidence that the object is a binary system composed of a supergiant B[e] star and an undetected companion. The emission lines with a non-variable RV could originate in a circumbinary region. For the Fe ii emission lines, we propose a simple geometrical two-component model where a compact source of Fe ii emission, moving

  6. Brackett γ radiation from the inner gaseous accretion disk, magnetosphere, and disk wind region of Herbig AeBe stars

    NASA Astrophysics Data System (ADS)

    Tambovtseva, L. V.; Grinin, V. P.; Weigelt, G.

    2016-05-01

    Various disk and outflow components such as the magnetosphere, the disk wind, the gaseous accretion disk, and other regions may contribute to the hydrogen line emission of young Herbig AeBe stars. Non-LTE modeling was performed to show the influence of the model parameters of each emitting region on the intensity and shape of the Brγ line profile, to present the spatial brightness distribution of each component, and to compare the contribution of each component to the total line emission. The modeling shows that the disk wind is the dominant contributor to the Brγ line rather than the magnetosphere and inner gaseous accretion disk. The contribution of the disk wind region to the Hα line is also considered.

  7. THE FOGGY DISKS SURROUNDING HERBIG Ae STARS: A THEORETICAL STUDY OF THE H{sub 2}O LINE SPECTRA

    SciTech Connect

    Cernicharo, J.; Ceccarelli, C.; Menard, F.; Pinte, C.; Fuente, A.

    2009-10-01

    Water is a key species in many astrophysical environments, but it is particularly important in protoplanetary disks. So far, observations of water in these objects have been scarce, but the situation should soon change thanks to the Herschel satellite. We report here a theoretical study of the water line spectrum of a protoplanetary disk surrounding Ae stars. We show that several lines will be observable with the HIFI instrument onboard the Herschel Space Observatory. We predict that some maser lines also could be observable with ground telescopes and we discuss how the predictions depend not only on the adopted physical and chemical model but also on the set of collisional coefficients used and on the H{sub 2} ortho-to-para ratio through its effect on collisional excitation. This makes the water line observations a powerful, but dangerous-if misused-diagnostic tool.

  8. A new photometric study of Herbig Ae/Be stars in the infrared

    NASA Astrophysics Data System (ADS)

    Chen, P. S.; Shan, H. G.; Zhang, P.

    2016-04-01

    In this paper we collected almost all HAeBe stars known so far (253 sources in total) to photometrically study their infrared properties. The 2MASS, WISE, IRAS and AKARI data are employed to make analyses. It is shown from several two-color diagrams that from 1 μm to 60 μm infrared radiations from circumstellar disks with the power law distribution play a very important role for infrared excesses which are much larger than that for ordinary Be stars. In the WISE two-color diagram, (W2-W3) vs. (W1-W2), some sources show thermal emissions probably due to dust surrounded and enhanced PAH features at 3.3 and 11.3 μm. In the wavelength longer than 60 μm infrared radiations are not so influenced by the circumstellar disk, but mainly from the ISM surrounded.

  9. Linear spectropolarimetry across the optical spectrum of Herbig Ae/Be stars

    NASA Astrophysics Data System (ADS)

    Ababakr, K. M.; Oudmaijer, R. D.; Vink, J. S.

    2016-09-01

    We present the results of spectropolarimetric observations of 12 Herbig Ae/Be objects. Our data have the largest spectropolarimetric wavelength coverage, 4560-9480 Å, published to date. A change in linear polarization across the H α line, is detected in all objects. Such a line effect reveals the fact that stellar photons are scattered off free electrons that are not distributed in a spherically symmetric volume, suggesting the presence of small discs around these accreting objects. Thanks to the large wavelength coverage, we can report that H α is the spectral line in the optical wavelength range that is most sensitive to revealing deviations from spherical symmetry, and the one most likely to show a line effect across the polarization in such cases. Few other spectral lines display changes in polarization across the line. In addition, H α is the only line which shows an effect across its absorption component in some sources. We present a scenario explaining this finding and demonstrate that the detection of the line effect strongly relies on the number of photons scattered into our line of sight. We highlight the special case of R Mon, which is the only object in our sample to show many lines with a polarization effect, which is much stronger than in all other objects. Given that the object and its nebulosity is spatially resolved, we argue that this is due to scattering of the stellar and emission spectrum off circumstellar dust.

  10. High-resolution 25 μm Imaging of the Disks around Herbig Ae/Be Stars

    NASA Astrophysics Data System (ADS)

    Honda, M.; Maaskant, K.; Okamoto, Y. K.; Kataza, H.; Yamashita, T.; Miyata, T.; Sako, S.; Fujiyoshi, T.; Sakon, I.; Fujiwara, H.; Kamizuka, T.; Mulders, G. D.; Lopez-Rodriguez, E.; Packham, C.; Onaka, T.

    2015-05-01

    We imaged circumstellar disks around 22 Herbig Ae/Be stars at 25 μm using Subaru/COMICS and Gemini/T-ReCS. Our sample consists of an equal number of objects from each of the two categories defined by Meeus et al.; 11 group I (flaring disk) and II (flat disk) sources. We find that group I sources tend to show more extended emission than group II sources. Previous studies have shown that the continuous disk is difficult to resolve with 8 m class telescopes in the Q band due to the strong emission from the unresolved innermost region of the disk. This indicates that the resolved Q-band sources require a hole or gap in the disk material distribution to suppress the contribution from the innermost region of the disk. As many group I sources are resolved at 25 μm, we suggest that many, but not all, group I Herbig Ae/Be disks have a hole or gap and are (pre-)transitional disks. On the other hand, the unresolved nature of many group II sources at 25 μm supports the idea that group II disks have a continuous flat disk geometry. It has been inferred that group I disks may evolve into group II through the settling of dust grains into the mid-plane of the protoplanetary disk. However, considering the growing evidence for the presence of a hole or gap in the disk of group I sources, such an evolutionary scenario is unlikely. The difference between groups I and II may reflect different evolutionary pathways of protoplanetary disks. Based on data collected at the Subaru Telescope, via the time exchange program between Subaru and the Gemini Observatory. The Subaru Telescope is operated by the National Astronomical Observatory of Japan.

  11. The structure of disks around Herbig Ae/Be stars as traced by CO ro-vibrational emission

    NASA Astrophysics Data System (ADS)

    van der Plas, G.; van den Ancker, M. E.; Waters, L. B. F. M.; Dominik, C.

    2015-02-01

    Aims: We study the emission and absorption of CO ro-vibrational lines in the spectra of intermediate mass pre-main-sequence stars with the aim to determine both the spatial distribution of the CO gas and its physical properties. We also aim to correlate CO emission properties with disk geometry. Methods: Using high-resolution spectra containing fundamental and first overtone CO ro-vibrational emission, observed with CRIRES on the VLT, we probe the physical properties of the circumstellar gas by studying its kinematics and excitation conditions. Results: We detect and spectrally resolve CO fundamental ro-vibrational emission in 12 of the 13 stars observed, and in two cases in absorption. Conclusions: Keeping in mind that we studied a limited sample, we find that the physical properties and spatial distribution of the CO gas correlate with disk geometry. Flaring disks show highly excited CO fundamental emission up to vu = 5, while self-shadowed disks show CO emission that is not as highly excited. Rotational temperatures range between 250-2000 K. The 13CO rotational temperatures are lower than those of 12CO. The vibrational temperatures in self-shadowed disks are similar to or slightly below the rotational temperatures, suggesting that thermal excitation or IR pumping is important in these lines. In flaring disks the vibrational temperatures reach as high as 6000 K, suggesting fluorescent pumping. Using a simple kinematic model we show that the CO inner radius of the emitting region is ≈10 au for flaring disks and ≤1 au for self-shadowed disks. Comparison with hot dust and other gas tracers shows that CO emission from the disks around Herbig Ae/Be stars, in contrast to T Tauri stars, does not necessarily trace the circumstellar disk up to, or inside the dust sublimation radius, Rsubl. Rather, the onset of the CO emission starts from ≈Rsubl for self-shadowed disks, to tens of Rsubl for flaring disks. It has recently been postulated that group I Herbig stars may

  12. HIGH-CONTRAST NEAR-INFRARED POLARIZATION IMAGING OF MWC480

    SciTech Connect

    Kusakabe, N.; Hashimoto, J.; Kudo, T.; Grady, C. A.; Sitko, M. L.; Werren, C.; Day, A. N.; Beerman, L. C.; Fukagawa, M.; Muto, T.; Wisniewski, J. P.; Min, M.; Mayama, S.; Lynch, D. K.; Russell, R. W.; Brafford, S. M.; Kuzuhara, M.; Brandt, T. D.; Abe, L.; Brandner, W.; and others

    2012-07-10

    One of the key predictions of modeling from the IR excess of Herbig Ae stars is that for protoplanetary disks, where significant grain growth and settling has occurred, the dust disk has flattened to the point that it can be partially or largely shadowed by the innermost material at or near the dust sublimation radius. When the self-shadowing has already started, the outer disk is expected to be detected in scattered light only in the exceptional cases when the scale height of the dust disk at the sublimation radius is smaller than usual. High-contrast imaging combined with the IR spectral energy distribution allow us to measure the degree of flattening of the disk, as well as to determine the properties of the outer disk. We present polarimetric differential imaging in the H band obtained with Subaru/HiCIAO of one such system, MWC 480. The HiCIAO data were obtained at a historic minimum of the NIR excess. The disk is detected in scattered light from 0.''2 to 1.''0 (27.4-137 AU). Together with the marginal detection of the disk from 1998 February 24 by Hubble Space Telescope/NICMOS, our data constrain the opening half-angle for the disk to lie between 1.{sup 0}3 {<=}{theta} {<=} 2.{sup 0}2. When compared with similar measures in CO for the gas disk from the literature, the dust disk subtends only {approx}30% of the gas disk scale height (H/R {approx} 0.03). Such a dust disk is a factor of 5-7 flatter than transitional disks, which have structural signatures that giant planets have formed.

  13. The 26th anniversary outburst of jet-driving symbiotic binary MWC 560: results from Chandra, Swift, and optical spectroscopy

    NASA Astrophysics Data System (ADS)

    Lucy, Adrian B.; Sokoloski, J. L.; Munari, U.; Kuin, N. P. M.; Darnley, M. J.; Luna, G. J. M.; Knigge, C.; Valisa, P.; Milani, A.

    2016-03-01

    The symbiotic star MWC 560 = V694 Mon, which is believed to usually drive a jet along the line of sight (e.g., Schmid et al. 2001), is undergoing a sustained outburst (ATel #8653) rivaling its previous brightest outburst of 1990 (Tomov et al. 1990, Leibowitz and Formiggini 2015).

  14. Absence of radial velocity variations in MWC 148 during the recent activity of HESS J0632+057

    NASA Astrophysics Data System (ADS)

    Casares, Jorge; Ribo, Marc; Paredes, Josep M.; Herrero, Artemio; Negueruela, Ignacio; Vilardell, Francesc

    2011-03-01

    MWC 148 is a B0pe-type star suspected to be the counterpart of the variable TeV gamma-ray source HESS J0632+057, which also shows variable radio and X-ray emission (Aharonian et al. 2007, A&A, 469, L1; Acciari et al. 2009, ApJ, 698, L94; Hinton et al. 2009, ApJ, 690, L101; Skilton et al. 2009, MNRAS, 399, 317; Falcone et al. 2009, ApJ, 708, L52). MWC 148 is thought to be a gamma-ray binary, although evidence of binarity from radial velocity measurements is still lacking (Aragona et al.

  15. Origin of the ionized wind in MWC 349A

    NASA Astrophysics Data System (ADS)

    Báez-Rubio, A.; Martín-Pintado, J.; Thum, C.; Planesas, P.; Torres-Redondo, J.

    2014-11-01

    The UC-HII region of MWC 349A is the prototype of an ionized wind driven by a massive star surrounded by a disk. Recent high angular resolution observations of the millimeter recombination lines have shown that the disk rotates with a Keplerian law in its outer parts. However, the kinematics of innermost regions in the UC-HII region of MWC 349A is still unknown, in particular, the radius where the wind is launched from the disk. We performed hydrogen recombination line observations with the Heterodyne Instrument for the Far Infrared (HIFI) onboard the Herschel Space Observatory to study the kinematics of its innermost regions by studying their spectral features. In addition to the two laser peaks, we report the first detection of two new components that are blueshifted with respect to the laser peaks for all the recombination lines with principal quantum number n ≤ 21. These new spectral features originate from the region where the wind is ejected from the disk. We used our 3D non-LTE radiative transfer model for recombination lines (MORELI) to show that these features are consistent with the wind being ejected at a radius of ~24 AU from the star, which supports magnetohydrodynamic wind models. The observed HIFI profiles are available online as FITS files at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/571/L4Appendix A is available in electronic form at http://www.aanda.org

  16. Asymmetric features in the protoplanetary disk MWC 758

    NASA Astrophysics Data System (ADS)

    Benisty, M.; Juhasz, A.; Boccaletti, A.; Avenhaus, H.; Milli, J.; Thalmann, C.; Dominik, C.; Pinilla, P.; Buenzli, E.; Pohl, A.; Beuzit, J.-L.; Birnstiel, T.; de Boer, J.; Bonnefoy, M.; Chauvin, G.; Christiaens, V.; Garufi, A.; Grady, C.; Henning, T.; Huelamo, N.; Isella, A.; Langlois, M.; Ménard, F.; Mouillet, D.; Olofsson, J.; Pantin, E.; Pinte, C.; Pueyo, L.

    2015-06-01

    Context. The study of dynamical processes in protoplanetary disks is essential to understand planet formation. In this context, transition disks are prime targets because they are at an advanced stage of disk clearing and may harbor direct signatures of disk evolution. Aims: We aim to derive new constraints on the structure of the transition disk MWC 758, to detect non-axisymmetric features and understand their origin. Methods: We obtained infrared polarized intensity observations of the protoplanetary disk MWC 758 with VLT/SPHERE at 1.04 μm to resolve scattered light at a smaller inner working angle (0.093'') and a higher angular resolution (0.027'') than previously achieved. Results: We observe polarized scattered light within 0.53'' (148 au) down to the inner working angle (26 au) and detect distinct non-axisymmetric features but no fully depleted cavity. The two small-scale spiral features that were previously detected with HiCIAO are resolved more clearly, and new features are identified, including two that are located at previously inaccessible radii close to the star. We present a model based on the spiral density wave theory with two planetary companions in circular orbits. The best model requires a high disk aspect ratio (H/r ~ 0.20 at the planet locations) to account for the large pitch angles which implies a very warm disk. Conclusions: Our observations reveal the complex morphology of the disk MWC 758. To understand the origin of the detected features, the combination of high-resolution observations in the submillimeter with ALMA and detailed modeling is needed. Based on observations performed with VLT/SPHERE under program ID 60-9389(A).Appendices are available in electronic form at http://www.aanda.orgESO data is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/578/L6

  17. Undergraduate Observations of Separation and Position Angle of Double Stars WDS J05460+2119AB (ARY 6AD and ARY 6 AE) at Manzanita Observatory (Abstract)

    NASA Astrophysics Data System (ADS)

    HOffert, M. J.; Weise, E.; Clow, J.; Hirzel, J.; Leeder, B.; Molyneux, S.; Scutti, N.; Spartalis, S.; Takuhara, C.

    2014-12-01

    (Abstract only) Six beginning astronomy students, part of an undergraduate stellar astronomy course, one advanced undergraduate student assistant, and a professor measured the position angles and separations of Washington Double Stars (WDS) J05460+2119 (= WDS J05460+2119AB; also known as ARY 6 AD and ARY 6 AE). The measurements were made at the Manzanita Observatory (116º 20' 42" W, 32º 44' 5" N) of the Tierra Astronomical Institute on 10 Blackwood Road in Boulevard, California (www.youtube.com/watch?v=BHVdeMGBGDU), at an elevation of 4,500 ft. A Celestron 11-inch HD Edge telescope was used to measure the position angles and separations of ARY 6 AD and ARY 6 AE. The averages of our measurements are as follows: separation AD: trial 1 124.1 arcseconds and trial 2 124.5 arcseconds; separation AE: trial 1 73.3 arcseconds and trial 2 73.8 arcseconds. The averages of positon angle for AD: trial 1 159.9 degrees and trial 2 161.3 degrees, for AE: trial 1 232.6 degrees and trial 2 233.7 degrees.

  18. VizieR Online Data Catalog: JCMT Gould Belt Survey: Serpens MWC 297 (Rumble+, 2015)

    NASA Astrophysics Data System (ADS)

    Rumble, D.; Hatchell, J.; Gutermuth, R. A.; Kirk, H.; Buckle, J.; Beaulieu, S. F.; Berry, D. S.; Broekhoven-Fiene, H.; Currie, M. J.; Fich, M.; Jenness, T.; Johnstone, D.; Mottram, J. C.; Nutter, D.; Pattle, K.; Pineda, J. E.; Quinn, C.; Salji, C.; Tisi, S.; Walker-Smith, S.; Di, Francesco J.; Hogerheijde, M. R.; Ward-thompson, D.; Allen, L. E.; Cieza, L. A.; Dunham, M. M.; Harvey, P. M.; Stapelfeldt, K. R.; Bastien, P.; Butner, H.; Chen, M.; Chrysostomou, A.; Coude, S.; Davis, C. J.; Drabek-Maunder, E.; Duarte-Cabral, A.; Fiege, J.; Friberg, P.; Friesen, R.; Fuller, G. A.; Graves, S.; Greaves, J.; Gregson, J.; Holland, W.; Joncas, G.; Kirk, J. M.; Knee, L. B. G.; Mairs, S.; Marsh, K.; Matthews, B. C.; Moriarty-Schieven, G.; Rawlings, J.; Richer, J.; Robertson, D.; Rosolowsky, E.; Sadavoy, S.; Thomas, H.; Tothill, N.; Viti, S.; White, G. J.; Wilson, C. D.; Wouterloot, J.; Yates, J.; Zhu, M.

    2015-09-01

    Serpens MWC 297 was observed with SCUBA-2 on the 2012 July 5 and 8 as part of the JCMT GBS MJLSG33 SCUBA-2 Serpens Campaign. Continuum observations at 850 and 450um were made using fully sampled 30 arcmin diameter circular regions centered on RA=18:28:13.8, DE=-03:44:01.7 (J2000). The MWC 297 region was observed twice by Spitzer in the mid-infrared, first as part of the Spitzer Young Clusters Survey (SYC; Gutermuth et al., 2009, Cat. J/ApJS/184/18) and secondly as part of the Spitzer legacy programme 'Gould's Belt: star formation in the solar neighbourhood' (SGBS, PID: 30574). In both surveys, mapping observations were taken at 3.6, 4.5, 5.8 and 8.0um with the Infrared Array Camera (IRAC) and at 24um with the Multiband Imaging Photometer for Spitzer (MIPS). (3 data files).

  19. The asymmetric profile of the H76 alpha line emission from MWC349

    NASA Technical Reports Server (NTRS)

    Rodriquez, L. F.; Canto, J.; Escalante, V.; Moran, J. M.

    1986-01-01

    MWC349 is an emission-line star found by Merrill, Humason and Burwell (1932). Braes, Habing and Schoenmaker (1972) discovered that it is a strong radio source. The radio emission originates in a massive ionized wind that is expanding with a velocity of about 50 km s(-1). Its continuum spectrum fits well a nu(0.6) power law from the cm wavelengths to the far-IR. Radio recombination line emission from the envelope of MWC349 was first detected by Altenhoff, Strittmatter and Wendker (1981). We have obtained good signal-to-noise ratio, Very Large Array observations of the H76 alpha radio recombination line from the ionized wind of MWC349. Our data reveal that the profile is markedly asymmetric, with a steep rise on the blue side. This asymmetry could be due to non-LTE effects in the formation and transfer of the line or to intrinsic asymmetries in the envelope. Our analysis suggests that most probably the peculiar profile is caused by a non-LTE enhancement of the line emission from the side of the envelope nearer to the observer. This asymmetry has the opposite sense than that observed in optical and IR recombination lines, where a different effect (absorption of the stellar continuum by the gas in the wind between the star and the observer) is known to be dominant, leading to the classic P Cygni profile. We propose that the profiles of the radio recombination lines from ionized stellar winds will have this characteristic shape, while optical and IR recombination lines are characterized by P Cygni-like profiles. Unfortunately, at present the detection of radio recombination lines from ionized stellar winds is only feasible for MWC349 and a few other objects.

  20. Modelling the asymmetric wind of the luminous blue variable binary MWC 314

    NASA Astrophysics Data System (ADS)

    Lobel, A.; Groh, J. H.; Martayan, C.; Frémat, Y.; Torres Dozinel, K.; Raskin, G.; Van Winckel, H.; Prins, S.; Pessemier, W.; Waelkens, C.; Hensberge, H.; Dumortier, L.; Jorissen, A.; Van Eck, S.; Lehmann, H.

    2013-11-01

    Aims: We present a spectroscopic analysis of MWC 314, a luminous blue variable (LBV) candidate with an extended bipolar nebula. The detailed spectroscopic variability is investigated to determine if MWC 314 is a massive binary system with a supersonically accelerating wind or a low-mass B[e] star. We compare the spectrum and spectral energy distribution to other LBVs (such as P Cyg) and find very similar physical wind properties, indicating strong kinship. Methods: We combined long-term high-resolution optical spectroscopic monitoring and V-band photometric observations to determine the orbital elements and stellar parameters and to investigate the spectral variability with the orbital phases. We developed an advanced model of the large-scale wind-velocity and wind-density structure with 3-D radiative transfer calculations that fit the orbitally modulated P Cyg profile of He i λ5876, showing outflow velocities above 1000 km s-1. Results: We find that MWC 314 is a massive semi-detached binary system of ≃1.22 AU, observed at an inclination angle of i = 72.8° with an orbital period of 60.8 d and e = 0.23. The primary star is a low-vsini LBV candidate of m1 = 39.6 M⊙ and R1 = 86.8 R⊙. The detailed radiative transfer fits show that the geometry of wind density is asymmetric around the primary star with increased wind density by a factor of 3.3, which leads the orbit of the primary. The variable orientation causes the orbital modulation that is observed in absorption portions of P Cyg wind lines. Wind accretion in the system produces a circumbinary disc. Conclusions: MWC 314 is in a crucial evolutionary phase of close binary systems, when the massive primary star has its H envelope being stripped and is losing mass to a circumbinary disc. MWC 314 is a key system for studying the evolutionary consequences of these effects. Table 1, Figs. 1-4, 9, 10, 14-16, 18-20, 23 are available in electronic form at http://www.aanda.org

  1. The Growing-up of a Star

    NASA Astrophysics Data System (ADS)

    2008-01-01

    Using ESO's Very Large Telescope Interferometer, astronomers have probed the inner parts of the disc of material surrounding a young stellar object, witnessing how it gains its mass before becoming an adult. ESO PR Photo 03/08 ESO PR Photo 03a/08 The disc around MWC 147 (Artist's Impression) The astronomers had a close look at the object known as MWC 147, lying about 2,600 light years away towards the constellation of Monoceros ('the Unicorn'). MWC 147 belongs to the family of Herbig Ae/Be objects. These have a few times the mass of our Sun and are still forming, increasing in mass by swallowing material present in a surrounding disc. MWC 147 is less than half a million years old. If one associated the middle-aged, 4.6 billion year old Sun with a person in his early forties, MWC 147 would be a 1-day-old baby [1]. The morphology of the inner environment of these young stars is however a matter of debate and knowledge of it is important to better understand how stars and their cortège of planets form. The astronomers Stefan Kraus, Thomas Preibisch, and Keiichi Ohnaka have used the four 8.2-m Unit Telescopes of ESO's Very Large Telescope to this purpose, combining the light from two or three telescopes with the MIDI and AMBER instruments. "With our VLTI/MIDI and VLTI/AMBER observations of MWC147, we combine, for the first time, near- and mid-infrared interferometric observations of a Herbig Ae/Be star, providing a measurement of the disc size over a wide wavelength range [2]," said Stefan Kraus, lead-author of the paper reporting the results. "Different wavelength regimes trace different temperatures, allowing us to probe the disc's geometry on the smaller scale, but also to constrain how the temperature changes with the distance from the star." The near-infrared observations probe hot material with temperatures of up to a few thousand degrees in the innermost disc regions, while the mid-infrared observations trace cooler dust further out in the disc. The

  2. AE AURIGAE: FIRST DETECTION OF NON-THERMAL X-RAY EMISSION FROM A BOW SHOCK PRODUCED BY A RUNAWAY STAR

    SciTech Connect

    Lopez-Santiago, J.; Pereira, V.; De Castro, E.; Miceli, M.; Bonito, R.; Del Valle, M. V.; Romero, G. E.; Albacete-Colombo, J. F.; Damiani, F.

    2012-09-20

    Runaway stars produce shocks when passing through interstellar medium at supersonic velocities. Bow shocks have been detected in the mid-infrared for several high-mass runaway stars and in radio waves for one star. Theoretical models predict the production of high-energy photons by non-thermal radiative processes in a number sufficiently large to be detected in X-rays. To date, no stellar bow shock has been detected at such energies. We present the first detection of X-ray emission from a bow shock produced by a runaway star. The star is AE Aur, which was likely expelled from its birthplace due to the encounter of two massive binary systems and now is passing through the dense nebula IC 405. The X-ray emission from the bow shock is detected at 30'' northeast of the star, coinciding with an enhancement in the density of the nebula. From the analysis of the observed X-ray spectrum of the source and our theoretical emission model, we confirm that the X-ray emission is produced mainly by inverse Compton upscattering of infrared photons from dust in the shock front.

  3. AE 941.

    PubMed

    2004-01-01

    AE 941 [Arthrovas, Neoretna, Psovascar] is shark cartilage extract that inhibits angiogenesis. AE 941 acts by blocking the two main pathways that contribute to the process of angiogenesis, matrix metalloproteases and the vascular endothelial growth factor signalling pathway. When initial development of AE 941 was being conducted, AEterna assigned the various indications different trademarks. Neovastat was used for oncology, Psovascar was used for dermatology, Neoretna was used for ophthalmology and Arthrovas was used for rheumatology. However, it is unclear if these trademarks will be used in the future and AEterna appears to only be using the Neovastat trademark in its current publications regardless of the indication. AEterna Laboratories signed commercialisation agreements with Grupo Ferrer Internacional SA of Spain and Medac GmbH of Germany in February 2001. Under the terms of the agreement, AEterna has granted exclusive commercialisation and distribution rights to AE 941 in oncology to Grupo Ferrer Internacional for the Southern European countries of France, Belgium, Spain, Greece, Portugal and Italy. It also has rights in Central and South America. Medac GmbH will have marketing rights in Germany, the UK, Scandinavia, Switzerland, Austria, Ireland, the Netherlands and Eastern Europe. In October 2002, AEterna Laboratories announced that it had signed an agreement with Australian healthcare products and services company Mayne Group for marketing AE 941 (as Neovastat) in Australia, New Zealand, Canada and Mexico. In March 2003, AEterna Laboratories announced it has signed an agreement with Korean based LG Life Sciences Ltd for marketing AE 941 (as Neovastat) in South Korea. The agreement provides AEterna with upfront and milestone payments, as well as a return on manufacturing and sales of AE 941. AEterna Laboratories had granted Alcon Laboratories an exclusive worldwide licence for AE 941 for ophthalmic products. However, this licence has been terminated. In

  4. EFFECT OF PHOTODESORPTION ON THE SNOW LINES AT THE SURFACE OF OPTICALLY THICK CIRCUMSTELLAR DISKS AROUND HERBIG Ae/Be STARS

    SciTech Connect

    Oka, Akinori; Nakamoto, Taishi; Inoue, Akio K.; Honda, Mitsuhiko

    2012-03-10

    We investigate the effect of photodesorption on the snow line position at the surface of a protoplanetary disk around a Herbig Ae/Be star, motivated by the detection of water ice particles at the surface of the disk around HD142527 by Honda et al. For this aim, we obtain the density and temperature structure in the disk with a 1+1D radiative transfer and determine the distribution of water ice particles in the disk by the balance between condensation, sublimation, and photodesorption. We find that photodesorption induced by far-ultraviolet radiation from the central star depresses the ice-condensation front toward the mid-plane and pushes the surface snow line significantly outward when the stellar effective temperature exceeds a certain critical value. This critical effective temperature depends on the stellar luminosity and mass, the water abundance in the disk, and the yield of photodesorption. We present an approximate analytic formula for the critical temperature. We separate Herbig Ae/Be stars into two groups on the HR diagram according to the critical temperature: one is the disks where photodesorption is effective and from which we may not find ice particles at the surface, and the other is the disks where photodesorption is not effective. We estimate the snow line position at the surface of the disk around HD142527 to be 100-300 AU, which is consistent with the water ice detection at >140 AU in the disk. All the results depend on the dust grain size in a complex way, and this point requires more work in the future.

  5. The binarity of Herbig Ae/Be stars observed with Adaptive Optics and spectroscopy. A study of the triple system TY CrA

    NASA Astrophysics Data System (ADS)

    Corporon, Patrice

    1998-03-01

    Multiplicity is a major issue in stellar astrophysics. Firstly, any stellar formation theory must explain the large abundance of multiple systems among Main Sequence and young low-mass T Tauri stars. Secondly, binary studies allow the direct determination of physical parameters. In the case of Herbig Ae/Be (HAeBe) stars, the binarity status is not well known; furthermore, direct mass determination are required to test stellar evolution models for these young intermediate mass objects. The first part of the thesis presents the results of a systematic search for HAeBe binaries in both hemispheres. Two complementary techniques were used to cover a large range of orbital period P: high angular resolution imaging with Adaptive Optics (AO) (binary separation ρ between 0.12'' and few arcseconds, i.e. P ≅ many years), and high resolution visible spectroscopy to study short orbital period (P ≅few hours to few months). Among the 68 HAeBe stars observed with ADONIS--ESO and PUEO--CFH AO instruments, 30 binaries (18 discovered) have been detected. 42 HAeBe stars have been surveyed with the CES--ESO and 'ELODIE, AURéLIE--OHP spectrographs. Radial velocity variations were found in 7 targets (4 are new spectroscopic binaries, 3 d. < P < 166 d.). In addition, the 7Li 6 708 Å absorption line (absent feature in simple HAeBe stars spectra) indicates the presence of a cooler companion in 6 HAeBe spectrum binaries, 4 of which are new detections. The observed visual binary frequency for HAeBe stars is of the order of 50%. For short period spectroscopic binaries (P < 100 days), the observed frequency is about 10%. Considering observational bias effects, these estimates are regarded as lower limits for the true HAeBe binary frequency. Based on our multi-color AO images, spectral types of twenty-two visual companions have been determined. A trend is found such that companions of Ae stars are low-mass T Tauri stars (spectral type K--M), while companions of Be stars are intermediate

  6. VizieR Online Data Catalog: Infrared photometric study of Herbig Ae/Be stars (Chen+, 2016)

    NASA Astrophysics Data System (ADS)

    Chen, P. S.; Shan, H. G.; Zhang, P.

    2016-04-01

    We took all sources listed in Paper I (Zhang et al., 2006Ap&SS.305...11Z) and added some sources from the literature (see the note in Table 1). Finally 252 HAeBe stars are found to have 2MASS and/or WISE data in which 53 sources are not presented in Paper I (Zhang et al., 2006Ap&SS.305...11Z). All 252 HAeBe stars are listed in Table 1. (2 data files).

  7. Revealing the sub-AU asymmetries of the inner dust rim in the disk around the Herbig Ae star R Coronae Austrinae

    NASA Astrophysics Data System (ADS)

    Kraus, S.; Hofmann, K.-H.; Malbet, F.; Meilland, A.; Natta, A.; Schertl, D.; Stee, P.; Weigelt, G.

    2009-12-01

    Context: Unveiling the structure of the disks around intermediate-mass pre-main-sequence stars (Herbig Ae/Be stars) is essential for our understanding of the star and planet formation process. In particular, models predict that in the innermost AU around the star, the dust disk forms a “puffed-up” inner rim, which should result in a strongly asymmetric brightness distribution for disks seen under intermediate inclination. Aims: Our aim is to constrain the sub-AU geometry of the inner disk around the Herbig Ae star R CrA and search for the predicted asymmetries. Methods: Using the VLTI/AMBER long-baseline interferometer, we obtained 24 near-infrared (H- and K-band) spectro-interferometric observations on R CrA. Observing with three telescopes in a linear array configuration, each data set samples three equally spaced points in the visibility function, providing direct information about the radial intensity profile. In addition, the observations cover a wide position angle range (~97°), also probing the position angle dependence of the source brightness distribution. Results: In the derived visibility function, we detect the signatures of an extended (Gaussian FWHM ~ 25 mas) and a compact component (Gaussian FWHM ~ 5.8 mas), with the compact component contributing about two-thirds of the total flux (both in H- and K-band). The brightness distribution is highly asymmetric, as indicated by the strong closure phases (up to ~40°) and the detected position angle dependence of the visibilities and closure phases. To interpret these asymmetries, we employ various geometric as well as physical models, including a binary model, a skewed ring model, and a puffed-up inner rim model with a vertical or curved rim shape. For the binary and vertical rim model, no acceptable fits could be obtained. On the other hand, the skewed ring model and the curved puffed-up inner rim model allow us to simultaneously reproduce the measured visibilities and closure phases. From these

  8. The compact Hα emitting regions of the Herbig Ae/Be stars HD 179218 and HD 141569 from CHARA spectro-interferometry

    NASA Astrophysics Data System (ADS)

    Mendigutía, I.; Oudmaijer, R. D.; Mourard, D.; Muzerolle, J.

    2016-10-01

    This work presents CHARA/VEGA Hα spectro-interferometry (R ˜ 6000, and λ/2B ˜ 1 mas) of HD 179218 and HD 141569, doubling the sample of Herbig Ae/Be (HAeBe) stars for which this type of observations is available so far. The observed Hα emission is spatially unresolved, indicating that the size of the Hα emitting region is smaller than ˜ 0.21 and 0.12 au for HD 179218 and HD 141529 (˜ 15 and 16 R★, respectively). This is smaller than for the two other HAeBes previously observed with the same instrumentation. Two different scenarios have been explored in order to explain the compact line emitting regions. A hot, several thousand K, blackbody disc is consistent with the observations of HD 179218 and HD 141569. Magnetospheric accretion (MA) is able to reproduce the bulk of the Hα emission shown by HD 179218, confirming previous estimates from MA shock modelling with a mass accretion rate of 10-8 M⊙ yr-1, and an inclination to the line of sight between 30 and 50°. The Hα profile of HD 141569 cannot be fitted from MA due to the high rotational velocity of this object. Putting the CHARA sample together, a variety of scenarios is required to explain the Hα emission in HAeBe stars -compact or extended, discs, accretion, and winds-, in agreement with previous Brγ spectro-interferometric observations.

  9. Disk Evaporation in Star Forming Regions

    NASA Technical Reports Server (NTRS)

    Hollenbach, David; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Young stars produce sufficient ultraviolet photon luminosity and mechanical luminosity in their winds to significantly affect the structure and evolution of the accretion disks surrounding them. The Lyman continuum photons create a nearly static, ionized, isothermal 10(exp 4) K atmosphere forms above the neutral disk at small distances from the star. Further out, they create a photoevaporative flow which relatively rapidly destroys the disk. The resulting slow (10-50 km/s) ionized outflow, which persists for approx. greater than 10(exp 5) years for disk masses M(sub d) approx. 0.3M(sub *), may explain the observational characteristics of many ultracompact HII regions. We compare model results to the observed radio free-free spectra and luminosities of ultracompact HII regions and to the interesting source MWC349, which is observed to produce hydrogen masers. We apply the results to Ae and Be stars in order to determine the lifetimes of disks around such stars. We also apply the results to the early solar nebula to explain the the dispersal of the solar nebula and the differences in hydrogen content in the giant planets. Finally, we model the small bright objects ("proplyds") observed in the Orion Nebula as disks around young, low mass stars which are externally illuminated by the UV photons from the nearby massive star Theta(sup 1) C.

  10. Statistical Mechanics of Monod–Wyman–Changeux (MWC) Models

    PubMed Central

    Marzen, Sarah; Garcia, Hernan G.; Phillips, Rob

    2013-01-01

    The 50th anniversary of the classic Monod–Wyman–Changeux (MWC) model provides an opportunity to survey the broader conceptual and quantitative implications of this quintessential biophysical model. With the use of statistical mechanics, the mathematical implementation of the MWC concept links problems that seem otherwise to have no ostensible biological connection including ligand–receptor binding, ligand-gated ion channels, chemotaxis, chromatin structure and gene regulation. Hence, a thorough mathematical analysis of the MWC model can illuminate the performance limits of a number of unrelated biological systems in one stroke. The goal of our review is twofold. First, we describe in detail the general physical principles that are used to derive the activity of MWC molecules as a function of their regulatory ligands. Second, we illustrate the power of ideas from information theory and dynamical systems for quantifying how well the output of MWC molecules tracks their sensory input, giving a sense of the “design” constraints faced by these receptors. PMID:23499654

  11. Inner disk clearing around the Herbig Ae star HD 139614: Evidence for a planet-induced gap?

    NASA Astrophysics Data System (ADS)

    Matter, A.; Labadie, L.; Augereau, J. C.; Kluska, J.; Crida, A.; Carmona, A.; Gonzalez, J. F.; Thi, W. F.; Le Bouquin, J.-B.; Olofsson, J.; Lopez, B.

    2016-02-01

    Spatially resolving the inner dust cavity (or gap) of the so-called (pre-)transitional disks is a key to understanding the connection between the processes of planetary formation and disk dispersal. The disk around the Herbig star HD 139614 is of particular interest since it presents a pretransitional nature with an au-sized gap structure that is spatially resolved by mid-infrared interferometry in the dust distribution. With the aid of new near-infrared interferometric observations, we aim to characterize the 0.1-10 au region of the HD 139614 disk further and then identify viable mechanisms for the inner disk clearing. We report the first multiwavelength modeling of the interferometric data acquired on HD 139614 with the VLTI instruments PIONIER, AMBER, and MIDI, complemented by Herschel/PACS photometric measurements. We first performed a geometrical modeling of the new near-infrared interferometric data, followed by radiative transfer modeling of the complete dataset using the code RADMC3D. We confirm the presence of a gap structure in the warm μm-sized dust distribution, extending from about 2.5 au to 6 au, and constrained the properties of the inner dust component: e.g., a radially increasing dust surface density profile, and a depletion in dust of ~103 relative to the outer disk. Since self-shadowing and photoevaporation appears unlikely to be responsible for the au-sized gap of HD 139614, we thus tested if dynamical clearing could be a viable mechanism using hydrodynamical simulations to predict the structure of the gaseous disk. Indeed, a narrow au-sized gap is consistent with the expected effect of the interaction between a single giant planet and the disk. Assuming that small dust grains are well coupled to the gas, we found that an approximately 3 Mjup planet located at ~4.5 au from the star could, in less than 1 Myr, reproduce most of the aspects of the dust surface density profile, while no significant depletion (in gas) occurred in the inner disk, in

  12. DISCOVERY OF A TWO-ARMED SPIRAL STRUCTURE IN THE GAPPED DISK AROUND HERBIG Ae STAR HD 100453

    SciTech Connect

    Wagner, Kevin; Apai, Daniel; Robberto, Massimo

    2015-11-01

    We present Very Large Telescope (VLT)/SPHERE adaptive optics imaging in the Y-, J-, H-, and K-bands of the HD 100453 system and the discovery of a two-armed spiral structure in a disk extending to 0.″37 (∼42 AU) from the star, with highly symmetric arms to the northeast and southwest. Inside of the spiral arms, we resolve a ring of emission from 0.″18 to 0.″25 (∼21–29 AU). By assuming that the ring is intrinsically circular we estimate an inclination of ∼34° from face on. We detect dark crescents on opposite sides (NW and SE) that begin at 0.″18 and continue to radii smaller than our inner working angle of 0.″15, which we interpret as the signature of a gap at ≲21 AU that has likely been cleared by forming planets. We also detect the ∼120 AU companion HD 100453 B, and by comparing our data to 2003 Hubble Space Telescope and VLT/NACO images we estimate an orbital period of ∼850 year. We discuss what implications the discovery of the spiral arms and finer structures of the disk may have on our understanding of the possible planetary system in HD 100453 and how the morphology of this disk compares to other related objects.

  13. Discovery of a Two-armed Spiral Structure in the Gapped Disk around Herbig Ae Star HD 100453

    NASA Astrophysics Data System (ADS)

    Wagner, Kevin; Apai, Daniel; Kasper, Markus; Robberto, Massimo

    2015-11-01

    We present Very Large Telescope (VLT)/SPHERE adaptive optics imaging in the Y-, J-, H-, and K-bands of the HD 100453 system and the discovery of a two-armed spiral structure in a disk extending to 0.″37 (˜42 AU) from the star, with highly symmetric arms to the northeast and southwest. Inside of the spiral arms, we resolve a ring of emission from 0.″18 to 0.″25 (˜21-29 AU). By assuming that the ring is intrinsically circular we estimate an inclination of ˜34° from face on. We detect dark crescents on opposite sides (NW and SE) that begin at 0.″18 and continue to radii smaller than our inner working angle of 0.″15, which we interpret as the signature of a gap at ≲21 AU that has likely been cleared by forming planets. We also detect the ˜120 AU companion HD 100453 B, and by comparing our data to 2003 Hubble Space Telescope and VLT/NACO images we estimate an orbital period of ˜850 year. We discuss what implications the discovery of the spiral arms and finer structures of the disk may have on our understanding of the possible planetary system in HD 100453 and how the morphology of this disk compares to other related objects.

  14. Spectroscopy, MOST photometry, and interferometry of MWC 314: is it an LBV or an interacting binary?

    NASA Astrophysics Data System (ADS)

    Richardson, Noel D.; Moffat, Anthony F. J.; Maltais-Tariant, Raphaël; Pablo, Herbert; Gies, Douglas R.; Saio, Hideyuki; St-Louis, Nicole; Schaefer, Gail; Miroshnichenko, Anatoly S.; Farrington, Chris; Aldoretta, Emily J.; Artigau, Étienne; Boyajian, Tabetha S.; Gordon, Kathryn; Jones, Jeremy; Matson, Rachel; McAlister, Harold A.; O'Brien, David; Raghavan, Deepak; Ramiaramanantsoa, Tahina; Ridgway, Stephen T.; Scott, Nic; Sturmann, Judit; Sturmann, Laszlo; Brummelaar, Theo ten; Thomas, Joshua D.; Turner, Nils; Vargas, Norm; Zharikov, Sergey; Matthews, Jaymie; Cameron, Chris; Guenther, David; Kuschnig, Rainer; Rowe, Jason; Rucinski, Slavek; Sasselov, Dimitar; Weiss, Werner

    2016-01-01

    MWC 314 is a bright candidate luminous blue variable (LBV) that resides in a fairly close binary system, with an orbital period of 60.753 ± 0.003 d. We observed MWC 314 with a combination of optical spectroscopy, broad-band ground- and space-based photometry, as well as with long baseline, near-infrared interferometry. We have revised the single-lined spectroscopic orbit and explored the photometric variability. The orbital light curve displays two minima each orbit that can be partially explained in terms of the tidal distortion of the primary that occurs around the time of periastron. The emission lines in the system are often double-peaked and stationary in their kinematics, indicative of a circumbinary disc. We find that the stellar wind or circumbinary disc is partially resolved in the K'-band with the longest baselines of the CHARA Array. From this analysis, we provide a simple, qualitative model in an attempt to explain the observations. From the assumption of Roche Lobe overflow and tidal synchronization at periastron, we estimate the component masses to be M1 ≈ 5 M⊙ and M2 ≈ 15 M⊙, which indicates a mass of the LBV that is extremely low. In addition to the orbital modulation, we discovered two pulsational modes with the MOST satellite. These modes are easily supported by a low-mass hydrogen-poor star, but cannot be easily supported by a star with the parameters of an LBV. The combination of these results provides evidence that the primary star was likely never a normal LBV, but rather is the product of binary interactions. As such, this system presents opportunities for studying mass-transfer and binary evolution with many observational techniques.

  15. 40 CFR Table 1 to Subpart Fff of... - Municipal Waste Combustor Units (MWC Units) Excluded From Subpart FFF 1

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 8 2010-07-01 2010-07-01 false Municipal Waste Combustor Units (MWC... FOR DESIGNATED FACILITIES AND POLLUTANTS Federal Plan Requirements for Large Municipal Waste... Part 62—Municipal Waste Combustor Units (MWC Units) Excluded From Subpart FFF 1 State MWC units...

  16. 40 CFR Table 1 to Subpart Fff of... - Municipal Waste Combustor Units (MWC Units) Excluded From Subpart FFF 1

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) Regional Waste Systems, Inc., Portland, Maine. Maryland Existing MWC facilities with an MWC unit capacity..., 2122 South Yukon Avenue, Tulsa, Oklahoma. Oregon Existing facilities at the following MWC sites: (a) Ogden Martin Systems, Marion County, Oregon. (b) Coos County, Coos Bay, Oregon. Pennsylvania...

  17. Submillimeter Array Imaging of the Maser Emission from the H30α Radio Recombination Line in MWC 349A

    NASA Astrophysics Data System (ADS)

    Weintroub, Jonathan; Moran, James M.; Wilner, David J.; Young, Ken; Rao, Ramprasad; Shinnaga, Hiroko

    2008-04-01

    We used the Submillimeter Array to map the angular distribution of the H30α recombination line (231.9 GHz) in the circumstellar region of the peculiar star MWC 349A. The resolution was 1.2'', but because of high signal-to-noise ratio we measured the positions of all maser components to accuracies better than 0.01'', at a velocity resolution of 1 km s-1. The two strongest maser components (called high-velocity components) at velocities near -14 and 32 km s-1 are separated by 0.048'' +/- 0.001'' (60 AU) along a position angle of 102° +/- 1°. The distribution of maser emission at velocities between and beyond these two strongest components were also provided. The continuum emission lies at the center of the maser distribution to within 10 mas. The masers appear to trace a nearly edge-on rotating disk structure, reminiscent of the water masers in Keplerian rotation in the nuclear accretion disk of the galaxy NGC 4258. However, the maser components in MWC 349A do not follow a simple Keplerian kinematic prescription with v ~ r-1/2, but have a larger power-law index. We explore the possibility that the high-velocity masers trace spiral density or shock waves. We also emphasize caution in the interpretation of relative centroid maser positions where the maser is not clearly resolved in position or velocity, and we present simulations that illustrate the range of applicability of the centroiding method.

  18. THE IMPACT OF PARTICULATE EMISSIONS CONTROL ON THE CONTROL OF OTHER MWC AIR EMISSIONS

    EPA Science Inventory

    On December 20, 1989, the Environmental Protection Agency (EPA) proposed revised new source performance standards for new municipal waste combustion (MWC) units and guidelines for existing sources. The proposed national regulations require tighter particulate matter control and a...

  19. On The Variability Of MWC 349A: Continuum Versus Hα Emission

    NASA Astrophysics Data System (ADS)

    Hillbrand, Alexander; Strelnitski, V.; Sliski, D.; Walker, G.; Bosworth, B.

    2012-01-01

    We report on a photometric monitoring of MWC 349A with the CCD-equipped Maria Mitchell Observatory's 24-inch telescope in 2009-2011. The goal of the project was to separate the Hα emission line variations from those of the continuum. We present our new method of the line/continuum separation (based on observations with two interference filters of different widths centered on Hα) and the results of the monitoring. Variations of both the red continuum and the Hα emission with amplitudes up to 0.1 magnitude on relatively short time scales (weeks and months) were superimposed on a secular drop of the star's brightness by approximately 0.3 magnitudes during the past 15 years. More recently, we found that the previously suspected periodicity with the period of ca. 240 days was followed by a long (more than a year) interval of virtually constant brightness. In our method of line/continuum separation, random and systematic errors in the outcomes from the two filters create an artificial anti-correlation between the extracted line and continuum intensities. However, considerable anti-correlation was observed even after smoothing the data for periods as long as a month. On shorter time scales, possible intrinsic anti-correlation has been corroborated by separating the emission line from the continuum with two independent filter combinations. If the intrinsic anti-correlation is real, it can be explained by the well-known inverse dependence of the recombination line emissivity on electron temperature, the latter being directly proportional to the ionizing ultraviolet continuum of the star. This project was supported by NSF/REU grant AST-0851892, the Presidential Award for Excellence in Science, Mathematics and Engineering Mentoring and the Nantucket Maria Mitchell Association.

  20. New photometric investigation of the Herbig Ae/Be star HD 52721, a close binary system: Evidence for the existence of large-scale azimuthal inhomogeneities

    NASA Astrophysics Data System (ADS)

    Pavlovskiy, S. E.; Pogodin, M. A.; Kupriyanov, V. V.; Gorshanov, D. L.

    2015-06-01

    We present new results of our photometry for the Herbig Be star HD 52721 obtained from January 16 to March 25, 2013. A new data reduction technique is used. Using this technique, we have also reanalyzed the previous results of our photometry for this object pertaining to the period from March 7 to March 28, 2010. The Be star HD 52721 is known as an eclipsing variable with the period P = 1d. 610. Two photometric minima observed during one period are a peculiarity of its photometric variability. They are separated in phase of the period P by 0.5 and differ from one another in depth by 0 m . 04. We have also detected additional minima observed at the phases of maximum brightness. We hypothesize that they can be associated with the existence of local azimuthal inhomogeneities rotating synchronously with the orbital motion of the binary component stars in the circumstellar envelope. When processing our CCD frames, we have applied an efficient CCD-frame rejection method that has allowed the accuracy of observations to be increased considerably. The CCD frames have been further processed using the Apex II software package, which is a universal software platform for astronomical image processing. We justify the need for additional photometric observations of HD 52721 in various color bands to confirm the hypothesis about the existence of azimuthal inhomogeneities in the program binary system and to analyze their physical properties.

  1. Transient Accretion Events in Herbig Ae/Be Star Spectra: The Evidence for Infalling Planetesimals in HD 100546 (B9E)

    NASA Technical Reports Server (NTRS)

    Grady, C. A.; Perez, M. R.; Bjorkman, K. S.

    1996-01-01

    Enhanced gaseous absorption resembling the high velocity circumstellar gas features in the spectrum of Beta Pic have been detected in IUE high dispersion spectra of the 2 Myr-old Herbig Be star, HD 100546, on 1995 March 9. The presence of atomic gas features in transitions of C I and O I implies that the material is produced by the pyrolysis of an unseen, solid body in a star-grazing orbit. The presence of weak Fe II absorption in the same spectrum with heavily saturated magnesium, aluminum, and silicon features is consistent with an origin in the sublimation of the olivenes detected in IRAS LRS and ISO SWS spectra of this star. The C I and O I detections suggest that, compared to Beta Pic, the planetesimals in this system contain substantial amounts of carbonaceous material. The presence of mildly refractory species such as Zn II and S II suggests that the planetesimal had not been substantially heated above 700 K during its previous lifetime.

  2. The accretion column of AE Aqr

    NASA Astrophysics Data System (ADS)

    Rodrigues, Claudia; Costa, D. Joaquim; Luna, Gerardo; Lima, Isabel J.; Silva, Karleyne M. G.; De Araujo, Jose Carlos N.; Coelho, Jaziel

    2016-07-01

    AE Aqr is a magnetic cataclysmic variable, whose white dwarf rotates at the very fast rate of 33 s modulating the flux from high-energies to optical wavelengths. There are many studies of the origin of its emission, which consider emission from a rotating magnetic field or from an accretion column. Recently, MAGIC observations have discarded AE Aqr emission in very high energy gamma-rays discarding non-thermal emission. Furthermore, soft and hard X-ray data from Swift and NuSTAR were fitted using thermal models. Here we present the modelling of AE Aqr X-ray spectra and light curve considering the emission of a magnetic accretion column using the Cyclops code. The model takes into consideration the 3D geometry of the system, allowing to properly represent the white-dwarf auto eclipse, the pre-shock column absorption, and the varying density and temperature of a tall accretion column.

  3. Use of MWC combined ash for highway embankment application

    SciTech Connect

    Shieh, C.S.; Kalajian, E.H.; Cosentino, P.; Egan, J.

    1998-07-01

    A field study was conducted to demonstrate the suitability of using municipal waste combustor (MWC) combined ash in high way embankment applications. The ash embankment was constructed using conventional techniques and was evaluated for the geotechnical properties and environmental acceptability. Field evaluation of the geotechnical performance of the embankment included specifically California Bearing Ratios (CBR), infiltration, pressuremeter, and cone penetrometer. Environmental analysis determined the ash embankment's leachate and runoff concentrations of As, Ba, Cd, Cr, Pb, Hg, Ag, and Se over time for comparison with drinking water and toxicity standards. Findings of the study indicated that combined ash could be sued as highway fill using conventional construction equipment and methods. The percent of the eight elemental metals in the ash lost to leachate or runoff after one year of exposure to natural rainfall was determined to be less than 0.01% and 0.005%, respectively, of their original weight in the ash. This indicates that greater then 99.99% of each of the eight elemental metals were retained in the ash. Concentrations of the eight EPA listed elemental metals in runoff and leachate from the ash embankment were below the EPA TCLP criteria and drinking water criteria. Results of the one-year monitoring study indicated that, based on the elemental metals examined, WMC combined ash is considered to be environmentally acceptable for highway fill materials applications.

  4. Constraints on nebular dynamics and chemistry based on observations of annealed magnesium silicate grains in comets and in disks surrounding Herbig Ae/Be stars

    PubMed Central

    Hill, Hugh G. M.; Grady, Carol A.; Nuth, Joseph A.; Hallenbeck, Susan L.; Sitko, Michael L.

    2001-01-01

    Understanding dynamic conditions in the Solar Nebula is the key to prediction of the material to be found in comets. We suggest that a dynamic, large-scale circulation pattern brings processed dust and gas from the inner nebula back out into the region of cometesimal formation—extending possibly hundreds of astronomical units (AU) from the sun—and that the composition of comets is determined by a chemical reaction network closely coupled to the dynamic transport of dust and gas in the system. This scenario is supported by laboratory studies of Mg silicates and the astronomical data for comets and for protoplanetary disks associated with young stars, which demonstrate that annealing of nebular silicates must occur in conjunction with a large-scale circulation. Mass recycling of dust should have a significant effect on the chemical kinetics of the outer nebula by introducing reduced, gas-phase species produced in the higher temperature and pressure environment of the inner nebula, along with freshly processed grains with “clean” catalytic surfaces to the region of cometesimal formation. Because comets probably form throughout the lifetime of the Solar Nebula and processed (crystalline) grains are not immediately available for incorporation into the first generation of comets, an increasing fraction of dust incorporated into a growing comet should be crystalline olivine and this fraction can serve as a crude chronometer of the relative ages of comets. The formation and evolution of key organic and biogenic molecules in comets are potentially of great consequence to astrobiology. PMID:11226213

  5. Constraints on nebular dynamics and chemistry based on observations of annealed magnesium silicate grains in comets and in disks surrounding Herbig Ae/Be stars.

    PubMed

    Hill, H G; Grady, C A; Nuth, J A; Hallenbeck, S L; Sitko, M L

    2001-02-27

    Understanding dynamic conditions in the Solar Nebula is the key to prediction of the material to be found in comets. We suggest that a dynamic, large-scale circulation pattern brings processed dust and gas from the inner nebula back out into the region of cometesimal formation-extending possibly hundreds of astronomical units (AU) from the sun-and that the composition of comets is determined by a chemical reaction network closely coupled to the dynamic transport of dust and gas in the system. This scenario is supported by laboratory studies of Mg silicates and the astronomical data for comets and for protoplanetary disks associated with young stars, which demonstrate that annealing of nebular silicates must occur in conjunction with a large-scale circulation. Mass recycling of dust should have a significant effect on the chemical kinetics of the outer nebula by introducing reduced, gas-phase species produced in the higher temperature and pressure environment of the inner nebula, along with freshly processed grains with "clean" catalytic surfaces to the region of cometesimal formation. Because comets probably form throughout the lifetime of the Solar Nebula and processed (crystalline) grains are not immediately available for incorporation into the first generation of comets, an increasing fraction of dust incorporated into a growing comet should be crystalline olivine and this fraction can serve as a crude chronometer of the relative ages of comets. The formation and evolution of key organic and biogenic molecules in comets are potentially of great consequence to astrobiology.

  6. Near-Infrared Polarimetric Imaging of Disks around Young Intermediate-mass Stars in SEEDS

    NASA Astrophysics Data System (ADS)

    Fukagawa, Misato; Hashimoto, Jun; Grady, C. A.; Momose, Munetake; Wisniewski, J. P.; Okamoto, Yoshiko; Muto, Takayuki; Kusakabe, Nobuhiko; Bonnefoy, Mickael; Kotani, Takayuki; Maruta, Yayoi; Tamura, Motohide; Seeds/Hiciao/Ao188 Collaboration,

    2013-07-01

    We present our recent results to directly image circumstellar disks around Herbig Fe/Ae/Be stars in scattered light with Subaru. Observations of such young disks are critically important to understand how disks evolve possibly under the mutual interaction with new-born planets. One of the observational approaches is direct imaging in scattered light, and the progress in this field since PPV can be found in the ability to prove inner regions of disks. This improvement largely owes to the technique of polarization differential imaging (PDI) which provides higher contrast by extracting scattered light from the disk while suppressing unpolarized stellar light. Strategic Exploration of Exoplanets and Disks with Subaru (SEEDS) is the project dedicated to exoplanet hunting and study of circumstellar disks by direct imaging. Since its beginning in 2009, thirteen Herbig Fe/Ae/Be stars have been observed primarily in H band (1.6 micron). The PDI method has been employed with adaptive optics, enabling us to look into the inner region as close as 0.2 arcsec (˜30 AU) in radius with the typical angular resolution of 0.06 arcsec (˜8 AU). As a result, the SEEDS imagery has newly uncovered rich structures such as spiral arms, inner holes, and gaps for (pre-)transitional disks while suggested the variably illuminated disks for primordial systems. The highlight is the discovery of two spiral arms each for SAO 206462 and MWC 758. The spiral feature has been uniquely found toward Herbig Fe/Aes so far, which might be due to their warmer disks producing arms loosely wound and more easily detected. The observed morphology can be interpreted by the density-wave model, and those disks are implied to harbor Jupiter-mass companions as the exciting sources of the spiral structures according to these models.

  7. INTERFEROMETRIC UPPER LIMITS ON MILLIMETER POLARIZATION OF THE DISKS AROUND DG Tau, GM Aur, AND MWC 480

    SciTech Connect

    Hughes, A. Meredith; Hull, Charles L. H.; Plambeck, Richard L.; Wilner, David J. E-mail: chat@astro.berkeley.edu

    2013-04-15

    Millimeter-wavelength polarization measurements offer a promising method for probing the geometry of magnetic fields in circumstellar disks. Single dish observations and theoretical work have hinted that magnetic field geometries might be predominantly toroidal, and that disks should exhibit millimeter polarization fractions of 2%-3%. While subsequent work has not confirmed these high polarization fractions, either the wavelength of observation or the target sources differed from the original observations. Here we present new polarimetric observations of three nearby circumstellar disks at 2'' resolution with the Submillimeter Array and the Combined Array for Research in Millimeter Astronomy. We reobserve GM Aur and DG Tau, the systems in which millimeter polarization detections have been claimed. Despite higher resolution and sensitivity at wavelengths similar to the previous observations, the new observations do not show significant polarization. We also add observations of a new HAeBe system, MWC 480. These observations demonstrate that a very low ({approx}<0.5%) polarization fraction is probably common at large ({approx}>100 AU) scales in bright circumstellar disks. We suggest that high-resolution observations may be worthwhile to probe magnetic field structure on linear distances smaller than the disk scale height, as well as in regions closer to the star that may have larger MRI-induced magnetic field strengths.

  8. 40 CFR Table 1 to Subpart Fff of... - Municipal Waste Combustor Units (MWC Units) Excluded From Subpart FFF 1

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... following MWC sites:(a) Solid Waste Disposal Authority of the City of Huntsville, Alabama. Florida Existing...) Wheelabrator Falls, Inc., Falls Township, Bucks County, PA. (f) York County Solid Waste and Refuse...

  9. 40 CFR Table 1 to Subpart Fff of... - Municipal Waste Combustor Units (MWC Units) Excluded From Subpart FFF 1

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... following MWC sites:(a) Solid Waste Disposal Authority of the City of Huntsville, Alabama. Florida Existing...) Wheelabrator Falls, Inc., Falls Township, Bucks County, PA. (f) York County Solid Waste and Refuse...

  10. PDS 144: The First Confirmed Herbig Ae-Herbig Ae Wide Binary

    NASA Technical Reports Server (NTRS)

    Hornbeck, J. B.; Grady, C. A.; Perrin, M. D.; Wisniewski, J. P.; Tofflemire, B. M.; Brown, A.; Holtzman, J. A.; Arraki, K.; Hamaguchi, K.; Woodgate, B.; Petre, R.; Daly, B.; Grogin, N. A.; Bonfield, D. G.; Williger, G. M.; Lauroesch, J. T.

    2012-01-01

    PDS 144 is a pair of Herbig Ae stars that are separated by 5.35" on the sky. It has previously been shown to have an A2Ve Herbig Ae star viewed at 83 deg inclination as its northern member and an A5Ve Herbig Ae star as its southern member. Direct imagery revealed a disk occulting PDS 144 N - the first edge-on disk observed around a Herbig Ae star. The lack of an obvious disk in direct imagery suggested PDS 144 S might be viewed face-on or not physically associated with PDS 144 N. Multi-epoch HST imagery of PDS 144 with a 5 yr baseline demonstrates PDS 144 N & S are comoving and have a common proper motion with TYC 6782-878-1. TYC 6782-878-1 has previously been identified as a member of Upper Sco sub-association A at d = 145 +/- 2 pc with an age of 5 - 10 Myr. Ground-based imagery reveals jets and a string of HH knots extending 13' (possibly further) which are aligned to within 7 deg +/- 6 deg on the sky. By combining proper motion data and the absence of a dark mid-plane with radial velocity data, we measure the inclination of PDS 144 S to be i = 73 deg +/- 7 deg. The radial velocity of the jets from PDS 144 N & S indicates they, and therefore their disks, are misaligned by 25 deg +/- 9 deg.. This degree of misalignment is similar to that seen in T-Tauri wide binaries.

  11. PDS 144: THE FIRST CONFIRMED Herbig Ae-Herbig Ae WIDE BINARY

    SciTech Connect

    Hornbeck, J. B.; Williger, G. M.; Lauroesch, J. T.; Grady, C. A.; Perrin, M. D.; Grogin, N. A.; Wisniewski, J. P.; Tofflemire, B. M.; Brown, A.; Holtzman, J. A.; Arraki, K.; Hamaguchi, K.; Woodgate, B.; Petre, R.; Bonfield, D. G.; Daly, B.

    2012-01-01

    PDS 144 is a pair of Herbig Ae stars that are separated by 5.''35 on the sky. It has previously been shown to have an A2Ve Herbig Ae star viewed at 83 Degree-Sign inclination as its northern member and an A5Ve Herbig Ae star as its southern member. Direct imagery revealed a disk occulting PDS 144 N-the first edge-on disk observed around a Herbig Ae star. The lack of an obvious disk in direct imagery suggested PDS 144 S might be viewed face-on or not physically associated with PDS 144 N. Multi-epoch Hubble Space Telescope imagery of PDS 144 with a 5 year baseline demonstrates PDS 144 N and S are comoving and have a common proper motion with TYC 6782-878-1. TYC 6782-878-1 has previously been identified as a member of Upper Sco sub-association A at d = 145 {+-} 2 pc with an age of 5-10 Myr. Ground-based imagery reveals jets and a string of Herbig-Haro knots extending 13' (possibly further) which are aligned to within 7 Degree-Sign {+-} 6 Degree-Sign on the sky. By combining proper motion data and the absence of a dark mid-plane with radial velocity data, we measure the inclination of PDS 144 S to be i = 73 Degree-Sign {+-} 7 Degree-Sign . The radial velocity of the jets from PDS 144 N and S indicates they, and therefore their disks, are misaligned by 25 Degree-Sign {+-} 9 Degree-Sign . This degree of misalignment is similar to that seen in T Tauri wide binaries.

  12. Stars

    NASA Astrophysics Data System (ADS)

    Capelato, Hugo Vicente

    1999-01-01

    We will begin our study with a more or less superficial inspection of the "forest" of stars that we see in the skies. The first thing we notice is that, as sources of light, they are much weaker than the Sun. Second, their apparent colors vary; from a bluish-white in most of them to a reddish-yellow, which is rarer. There is also a third aspect, though it is not very obvious to the naked eye: most of the stars group themselves in small families of two, three or more members. A good example is the Alpha Centauri, the closest star to us, which, in fact, is a triple system of stars. Another is the group of 7 stars that make up the Pleiades, which will be discussed later on. In fact, almost half of the stars are double systems with only two members, called binary stars. Most of these double stars, though together, are separated by several astronomical units (one astronomical unit, AU, is the distance from Earth to the sun: see Chapter 1), and revolve around each other over periods of several years. And yet the revolutions of some binary stars, separated by much smaller distances, occur in only a few hours! These stars are so close to each other that they can share enveloping material. Often this exchange occurs in a somewhat violent manner. Local explosions may occur, expelling matter away from the system. In other binary systems, where one of the components is a very compact, dense star, companion material flows more calmly, making up a light disk around the compact star.

  13. Lights, camera, A&E.

    PubMed

    Gould, Mark

    Channel 4 series 24 Hours in A&E was one of the television highlights of 2011. Filmed at King's College Hospital in London, it showed the reality of life in an A&E department and may have improved the public's understanding of nursing. PMID:22324233

  14. OT1_abaezrub_2: Unveiling the kinematics of the MWC49A's ionized disk and outflow with H-recombination line masers.

    NASA Astrophysics Data System (ADS)

    Báez-Rubio, A.

    2010-07-01

    % MWC349A, the unique H-maser source observed so far, is a massive star with an ionized outflow believed to be generated in its photoevaporating rotating circumstellar disk. We plan to use the unique spectral capabilities provided by HIFI to perform observations of basically all of the Hα recombination lines (from H26α to H15α) covered by this instrument. Spectral resolved profiles will reveal essential kinematics inormation of the inner regions of the ionized outflow and the rotating disk. The observed line profile will be compared with the prediction of our non-LTE 3D radiative transfer model to constrain key parameters of the disk-outflow system. From the model's prediction we will stablish if the inner disk is rotating with a Keplerian law, the rotation of the outflow and likely the presence of radial motions (accretion/excretion) in the disk and the location of the lunching point of the outflow. These parameters will help to discriminate between the models proposed for the origin of the outflows and the evolutionary state (pre-main sequence or evolved B[e] stars) of the central star.

  15. (abstract) Airborne Emission Spectrometer (AES)

    NASA Technical Reports Server (NTRS)

    Beer, Reinhard

    1994-01-01

    AES is a low-cost analog of the TES downlooking modes. Because AES operates at ambient temperature, limb-viewing is not possible. The first flight of AES took place in April 1994 on the NASA P3B aircraft out of Wallops Island, VA. While planned as an engineering test flight, spectra were successfully acquired both over the Atlantic Ocean and the area of the Great Dismal Swamp on the Virginia-North Carolina border. At this writing (July 1994), a second series of flights on the NASA DC8 aircraft out of Ames RC,CA is in progress. By the time of the workshop, a third series using the NASA C130 should have been accomplished.

  16. 40 CFR Table 1 to Subpart Fff of... - Municipal Waste Combustor Units (MWC Units) Excluded From Subpart FFF 1

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 9 2013-07-01 2013-07-01 false Municipal Waste Combustor Units (MWC Units) Excluded From Subpart FFF 1 1 Table 1 to Subpart FFF of Part 62 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF STATE PLANS FOR DESIGNATED FACILITIES AND...

  17. Acoustic emission characterization using AE (parameter) delay

    NASA Technical Reports Server (NTRS)

    Williams, J. H., Jr.; Lee, S. S.

    1983-01-01

    The acoustic emission (AE) parameter delay concept is defined as that particular measured value of a parameter at which a specified baseline level of cumulative AE activity is reached. The parameter can be from any of a broad range of elastic, plastic, viscoelastic, and fracture mechanics parameters, as well as their combinations. Such parameters include stress, load, strain, displacement, time, temperature, loading cycle, unloading stress, stress intensity factor, strain energy release rate, and crack tip plasticity zone size, while the AE activity may be AE event counts, ringdown counts, energy, event duration, etc., as well as their combinations. Attention is given to examples for the AE parameter delay concept, together with various correlations.

  18. First results of MWC SAS3 electromagnetic wave experiment on board of the Chibis-M satellite

    NASA Astrophysics Data System (ADS)

    Klimov, Stanislav; Ferencz, Csaba; Bodnár, László; Szegedi, Péter; Steinbach, Péter; Gotlib, Vladimir; Novikov, Denis; Belyayev, Serhiy; Marusenkov, Andrey; Ferencz, Orsolya; Korepanov, Valery; Lichtenberger, János; Hamar, Dániel

    2014-11-01

    The main goals of the Chibis-M mission are the testing of a new micro-satellite technology, the study of new physical processes related to lightning activity and the verification of possible monitoring techniques of Space Weather phenomena. In frames of the Chibis-M mission an electromagnetic wave complex MWC is installed on board of the satellite composed of electromagnetic sensors and SAS3 measuring unit. The obtained data show that the scientific instrumentation operates properly and produces interesting information. Here we present the first results of the first year of operation of the MWC in the ELF-VLF bands in different operation modes. An important conclusion is that basing on the experience of the first year it is possible to realize an effective and reliable Space Weather monitoring system using micro-satellites and simultaneously operating ground support equipments.

  19. Optical spectrophotometry of oscillations and flickering in AE Aquarii

    NASA Technical Reports Server (NTRS)

    Welsh, William F.; Horne, Keith; Oke, J. B.

    1993-01-01

    We observed rapid variations in the nova-like cataclysmic variable AE Aquarii for 1.7 hr with 4.3 s time resolution using the 30-channel (3227-10494 A) spectrophotometer on the Hale 5 m telescope. The 16.5 and 33.0 s oscillations show a featureless blue spectrum that can be represented by a blackbody with temperature and area much smaller than the accretion disk. Models consisting of the sum of a K star spectrum and a hydrogen slab in LTE at T = 6000-10,000 K can fit the spectrum of AE Aquarii reasonably well. The spectrum of a flare indicates optically thin gas with T = 8000-12,000 K. The energy released by the flare is large compared to typical stellar flares.

  20. Infrared observations of AE Aquarii

    NASA Technical Reports Server (NTRS)

    Tanzi, E. G.; Chincarini, G.; Tarenghi, M.

    1981-01-01

    Broadband infrared observations of the cataclysmic variable AE Aquarii are reported. The observations were obtained in the J, H, K and L filters with the InSb photometer attached to the 1-m telescope of the European Southern Observatory. The infrared energy distribution observed from 0.35 to 3.5 microns for phase 0.5 suggests a spectral type of K5 V for the secondary and a distance to the system of approximately 70 pc if an absolute magnitude of 7.3 is assumed. Monitoring of the flux at 2.2 microns reveals a variability with an amplitude of approximately 0.3 magnitude over one third of the orbital period, the nature of which is under investigation.

  1. Imaging and Spectroscopy of The Massive Binaries MWC 314 and HD 168625

    NASA Astrophysics Data System (ADS)

    Lobel, A.; Martayan, C.; Baade, D.; Mehner, A.; Groh, J. H.

    2015-12-01

    VLT-NACO imaging and spectroscopic monitoring of MWC 314 shows it is a hierarchical triple system consisting of a close massive binary that contains a Luminous Blue Variable (LBV), and a third companion bound in a wide orbit. We observe Discrete Absorption Components (DACs) in extended violet absorption wings of P Cyg He i lines at orbital phases when the primary is in front of the secondary. The DACs signal fast expanding wind regions of enhanced density and variable outflow velocity. We present a model of the circumbinary disc showing that the formation region of Fe ii emission lines in the disc extends to ˜26 au from the center of gravity for i=70∘. Direct imaging of the candidate LBV HD 168625 also reveals a companion bound in a wide orbit. A kinematic analysis of VLT-UVES slit spectra signals significantly different radial velocities of the [N ii] λ6584 emission line formation regions N-S across the inner loop-like nebular structures.

  2. The pulsar-like white dwarf in AE Aquarii

    NASA Astrophysics Data System (ADS)

    Ikhsanov, Nazar R.

    1998-10-01

    The spindown power of the compact companion in the close binary system AE Aqr essentially exceeds the bolometrical luminosity of the system. The interpretation of this phenomenon under various assumptions about the state and the nature of the primary companion is discussed. It is shown that the rapid braking on the compact companion of AE Aqr can be explained in terms of the pulsar mechanism provided the magnetic moment of the compact star mu ga 1.4 x 10(34) {R_mm G cm(3}) , that implies a magnetic field strength at the surface of the white dwarf of about 50 MG. Under this condition the spindown power is used predominantly for the generation of magneto-dipole waves and particle acceleration. A stream-fed, diskless mass-exchange picture with the average rate of mass transfer dot {M} ~ (0.5/5) x 10(17) {R_mm g s(-1}) is expected in the frame of the suggested model. Similarity of some properties of the X-ray emission observed from AE Aqr and canonical radio pulsars in the ROSAT energy range (e.g. the power law spectrum of pulsing component with alpha ~ -2 and the ratio L_{R_mm X}/L_{R_mm sd} ~ 10(-3) ) allows to suggest common mechanisms of particle acceleration and the polar cap heating in these systems.

  3. The AE-8 trapped electron model environment

    NASA Technical Reports Server (NTRS)

    Vette, James I.

    1991-01-01

    The machine sensible version of the AE-8 electron model environment was completed in December 1983. It has been sent to users on the model environment distribution list and is made available to new users by the National Space Science Data Center (NSSDC). AE-8 is the last in a series of terrestrial trapped radiation models that includes eight proton and eight electron versions. With the exception of AE-8, all these models were documented in formal reports as well as being available in a machine sensible form. The purpose of this report is to complete the documentation, finally, for AE-8 so that users can understand its construction and see the comparison of the model with the new data used, as well as with the AE-4 model.

  4. Waveform Analysis of AE in Composites

    NASA Technical Reports Server (NTRS)

    Prosser, William H.

    1998-01-01

    Advanced, waveform based acoustic emission (AE) techniques have been developed to evaluate damage mechanisms in the testing of composite materials. This approach, more recently referred to as Modal AE, provides an enhanced capability to discriminate and eliminate noise signals from those generated by damage mechanisms. Much more precise source location can also be obtained in comparison to conventional, threshold crossing arrival time determination techniques. Two successful examples of the application of Modal AE are presented in this work. In the first, the initiation of transverse matrix cracking in cross-ply, tensile coupons was monitored. In these tests, it was documented that the same source mechanism, matrix cracking, can produce widely different AE signal amplitudes dependent on laminate stacking sequence and thickness. These results, taken together with well known propagation effects of attenuation and dispersion of AE signals in composite laminates, cast further doubt on the validity of simple amplitude or amplitude distribution analysis for AE source determination. For the second example, delamination propagation in composite ring specimens was monitored. Pressurization of these composite rings is used to simulate the stresses in a composite rocket motor case. AE signals from delamination propagation were characterized by large amplitude flexural plate mode components which have long signal durations because of the large dispersion of this mode.

  5. AES analysis of barium fluoride thin films

    NASA Astrophysics Data System (ADS)

    Kashin, G. N.; Makhnjuk, V. I.; Rumjantseva, S. M.; Shchekochihin, Ju. M.

    1993-06-01

    AES analysis of thin films of metal fluorides is a difficult problem due to charging and decomposition of such films under electron bombardment. We have developed a simple algorithm for a reliable quantitative AES analysis of metal fluoride thin films (BaF 2 in our work). The relative AES sensitivity factors for barium and fluorine were determined from BaF 2 single-crystal samples. We have investigated the dependence of composition and stability of barium fluoride films on the substrate temperature during film growth. We found that the instability of BaF 2 films grown on GaAs substrates at high temperatures (> 525°C) is due to a loss of fluorine. Our results show that, under the optimal electron exposure conditions, AES can be used for a quantitative analysis of metal fluoride thin films.

  6. Advanced AE Techniques in Composite Materials Research

    NASA Technical Reports Server (NTRS)

    Prosser, William H.

    1996-01-01

    Advanced, waveform based acoustic emission (AE) techniques have been successfully used to evaluate damage mechanisms in laboratory testing of composite coupons. An example is presented in which the initiation of transverse matrix cracking was monitored. In these tests, broad band, high fidelity acoustic sensors were used to detect signals which were then digitized and stored for analysis. Analysis techniques were based on plate mode wave propagation characteristics. This approach, more recently referred to as Modal AE, provides an enhanced capability to discriminate and eliminate noise signals from those generated by damage mechanisms. This technique also allows much more precise source location than conventional, threshold crossing arrival time determination techniques. To apply Modal AE concepts to the interpretation of AE on larger composite specimens or structures, the effects of modal wave propagation over larger distances and through structural complexities must be well characterized and understood. To demonstrate these effects, measurements of the far field, peak amplitude attenuation of the extensional and flexural plate mode components of broad band simulated AE signals in large composite panels are discussed. These measurements demonstrated that the flexural mode attenuation is dominated by dispersion effects. Thus, it is significantly affected by the thickness of the composite plate. Furthermore, the flexural mode attenuation can be significantly larger than that of the extensional mode even though its peak amplitude consists of much lower frequency components.

  7. Clinical epidemiology of human AE in Europe.

    PubMed

    Vuitton, D A; Demonmerot, F; Knapp, J; Richou, C; Grenouillet, F; Chauchet, A; Vuitton, L; Bresson-Hadni, S; Millon, L

    2015-10-30

    This review gives a critical update of the situation regarding alveolar echinococcosis (AE) in Europe in humans, based on existing publications and on findings of national and European surveillance systems. All sources point to an increase in human cases of AE in the "historic endemic areas" of Europe, namely Germany, Switzerland, Austria and France and to the emergence of human cases in countries where the disease had never been recognised until the end of the 20th century, especially in central-eastern and Baltic countries. Both increase and emergence could be only due to methodological biases; this point is discussed in the review. One explanation may be given by changes in the animal reservoir of the parasite, Echinococcus multilocularis (increase in the global population of foxes in Europe and its urbanisation, as well as a possible increased involvement of pet animals as definitive infectious hosts). The review also focuses onto 2 more original approaches: (1) how changes in therapeutic attitudes toward malignant and chronic inflammatory diseases may affect the epidemiology of AE in the future in Europe, since a recent survey of such cases in France showed the emergence of AE in patients with immune suppression since the beginning of the 21st century; (2) how setting a network of referral centres in Europe based on common studies on the care management of patients might contribute to a better knowledge of AE epidemiology in the future. PMID:26346900

  8. Differential attack on mini-AES

    NASA Astrophysics Data System (ADS)

    Ajeng Gemellia, Asadini Dwi; Indarjani, Santi

    2012-05-01

    This paper presents the results of differential attack on Mini-AES algorithm. The differential trails are constructed using all combinations of propagation ratio without repetition. To give practical results, we implement the key extraction for differential characteristics which have the highest and lowest probability as a comparison. Based on total propagation ratio and complexity resulted, Mini-AES algorithms are vulnerable to differential attack. The best differential characteristic is the differential characteristic using a single active s-box with the propagation ratio of 8 / 16.

  9. The Gamma-Ray Source AGL J2241+4454 as the Possible Counterpart of MWC 656

    NASA Astrophysics Data System (ADS)

    Munar-Adrover, Pere; Sabatini, S.; Piano, Giovanni; Tavani, Marco; Nguyen, L. H.; Lucarelli, F.; Verrecchia, F.; Pittori, C.

    2016-10-01

    AGILE discovered the transient source AGL J2241+4454 in 2010, which triggered the study of the associated field allowing for the discovery of the first Be/black hole binary system: MWC 656. This binary was suggested to be the counterpart of AGL J2241+4454, but this association is still not robust. In this work we explore the archival AGILE and Fermi/Large Area Telescope (LAT) data to find more transient events compatible with AGL J2241+4454 and address the possibility to link them to the accretion/ejection processes of MWC 656. We found a total of nine other transient events with AGILE compatible with the position of AGL J2241+4454, besides the 2010 one. We folded these events with the period of the binary system and we could not associate the gamma-ray activity with any particular orbital phase. By stacking the 10 transient events we obtained a spectrum that extends between 100 MeV and 1 GeV, and we fitted it with a power law with a photon index {{Γ }}=2.3+/- 0.2. We searched the Fermi/LAT data in order to complement the gamma-ray information provided by AGILE but no significant results arose. To investigate this apparent contradiction between these telescopes, we studied the exposure of the field of AGL J2241+4454 in both instruments, and found significant differences. In particular, AGILE exposed, for a longer time and at a lower off-axis angular distance, the field of AGL J2241+4454. This fact, together with the energy-dependent sensitivity of both instruments, and the soft spectrum found in the stacking analysis, might explain why AGILE observed the transient events not seen by Fermi/LAT.

  10. Matt Rogers on AES Energy Storage

    ScienceCinema

    Rogers, Matt

    2016-07-12

    The Department of Energy and AES Energy Storage recently agreed to a $17.1M conditional loan guarantee commitment. This project will develop the first battery-based energy storage system to provide a more stable and efficient electrical grid for New York State's high-voltage transmission network. Matt Rogers is the Senior Advisor to the Secretary for Recovery Act Implementation.

  11. Cytosolic H+ microdomain developed around AE1 during AE1-mediated Cl-/HCO3- exchange.

    PubMed

    Johnson, Danielle E; Casey, Joseph R

    2011-04-01

    Microdomains, regions of discontinuous cytosolic solute concentration enhanced by rapid solute transport and slow diffusion rates, have many cellular roles. pH-regulatory membrane transporters, like the Cl−/HCO3− exchanger AE1, could develop H+ microdomains since AE1 has a rapid transport rate and cytosolic H+ diffusion is slow. We examined whether the pH environment surrounding AE1 differs from other cellular locations. As AE1 drives Cl−/HCO3− exchange, differences in pH, near and remote from AE1, were monitored by confocal microscopy using two pH-sensitive fluorescent proteins: deGFP4 (GFP) and mNectarine (mNect). Plasma membrane (PM) pH (defined as ∼1 μm region around the cell periphery) was monitored by GFP fused to AE1 (GFP.AE1), and mNect fused to an inactive mutant of the Na+-coupled nucleoside co-transporter, hCNT3 (mNect.hCNT3). GFP.AE1 to mNect.hCNT3 distance was varied by co-expression of different amounts of the two proteins in HEK293 cells. As the GFP.AE1–mNect.hCNT3 distance increased, mNect.hCNT3 detected the Cl−/HCO3− exchange-associated cytosolic pH change with a time delay and reduced rate of pH change compared to GFP.AE1. We found that a H+ microdomain 0.3 μm in diameter forms around GFP.AE1 during physiological HCO3− transport. Carbonic anhydrase isoform II inhibition prevented H+ microdomain formation. We also measured the rate of H+ movement from PM GFP.AE1 to endoplasmic reticulum (ER), using mNect fused to the cytosolic face of ER-resident calnexin (CNX.mNect). The rate of H+ diffusion through cytosol was 60-fold faster than along the cytosolic surface of the plasma membrane. The pH environment surrounding pH regulatory transport proteins may differ as a result of H+ microdomain formation, which will affect nearby pH-sensitive processes.

  12. A-type shell stars and infrared sources

    NASA Astrophysics Data System (ADS)

    Jaschek, M.; Jaschek, C.; Egret, D.

    1986-04-01

    Following the discovery of a dust cloud around an A-type shell star the authors examine the situation of all known Ae/A shell stars. They have found 19 stars of this group observed by IRAS, and of these 19, 8 are infrared anomalous emitters (IAE). The temperatures of the anomalous emitting sources are of the order of 50 - 400K, although three cases require two superposed cool sources. The proportion of IAE's among Ae/A shell stars is very high, when compared to a sample of non-shell A-type stars. This suggests a close link between the membership in the group and IAE.

  13. AES Water Architecture Study Interim Results

    NASA Technical Reports Server (NTRS)

    Sarguisingh, Miriam J.

    2012-01-01

    The mission of the Advanced Exploration System (AES) Water Recovery Project (WRP) is to develop advanced water recovery systems in order to enable NASA human exploration missions beyond low earth orbit (LEO). The primary objective of the AES WRP is to develop water recovery technologies critical to near term missions beyond LEO. The secondary objective is to continue to advance mid-readiness level technologies to support future NASA missions. An effort is being undertaken to establish the architecture for the AES Water Recovery System (WRS) that meets both near and long term objectives. The resultant architecture will be used to guide future technical planning, establish a baseline development roadmap for technology infusion, and establish baseline assumptions for integrated ground and on-orbit environmental control and life support systems (ECLSS) definition. This study is being performed in three phases. Phase I of this study established the scope of the study through definition of the mission requirements and constraints, as well as indentifying all possible WRS configurations that meet the mission requirements. Phase II of this study focused on the near term space exploration objectives by establishing an ISS-derived reference schematic for long-duration (>180 day) in-space habitation. Phase III will focus on the long term space exploration objectives, trading the viable WRS configurations identified in Phase I to identify the ideal exploration WRS. The results of Phases I and II are discussed in this paper.

  14. A possible scenario of the flaring activity in AE Aqr

    NASA Astrophysics Data System (ADS)

    Isakova, P. B.; Zhilkin, A. G.; Bisikalo, D. V.; Ikhsanov, N. R.

    2016-02-01

    The flow structure in magnetic cataclysmic variables with strong magnetic field and fast rotation of the white dwarf was investigated. We model the AE Aqr system as a representative observational object whose spin period of the white dwarf is about 1000 times shorter than the orbital period of the system. Observations show that in spite of the fast rotation some part of the material from the inner Lagrangian point is present in the Roche lobe of the white dwarf. We analyze the possible physical mechanisms that can lead to the less effective angular momentum transfer from the rotating magnetosphere to the inflowing material. Among these mechanisms are the ambipolar diffusion, the pressure of the magneto-dipole radiation, the relativistic retard of magnetic field lines and the incomplete penetration of the magnetic field to plasma. Results of our analysis show that the last mechanism is the most effective. Taking this effect into account we can find the flow structure that is in an agreement with observations. The unique flaring activity is the most prominent property of the AE Aqr system. In this system, the active and quiescent phases alternate. The flaring activity may be caused by the transitions between the laminar and turbulent regimes. In the laminar regime, the flow goes around the star and collides with the material flowing from the inner Lagrangian point. As a result the shock occurs which produces the flow turbulence. In the turbulent regime, the magnetosphere pushes the material away from the Roche lobe of the white dwarf and the flow becomes quickly laminar again.

  15. 22 CFR 120.30 - The Automated Export System (AES).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 22 Foreign Relations 1 2013-04-01 2013-04-01 false The Automated Export System (AES). 120.30... DEFINITIONS § 120.30 The Automated Export System (AES). The Automated Export System (AES) is the Department of... data and defense services shall be reported directly to the Directorate of Defense Trade Controls...

  16. 22 CFR 120.30 - The Automated Export System (AES).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 22 Foreign Relations 1 2014-04-01 2014-04-01 false The Automated Export System (AES). 120.30... DEFINITIONS § 120.30 The Automated Export System (AES). The Automated Export System (AES) is the Department of... data and defense services shall be reported directly to the Directorate of Defense Trade Controls...

  17. 22 CFR 120.30 - The Automated Export System (AES).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 1 2012-04-01 2012-04-01 false The Automated Export System (AES). 120.30... DEFINITIONS § 120.30 The Automated Export System (AES). The Automated Export System (AES) is the Department of... data and defense services shall be reported directly to the Directorate of Defense Trade Controls...

  18. The far-infrared behaviour of Herbig Ae/Be discs: Herschel PACS photometry

    NASA Astrophysics Data System (ADS)

    Pascual, N.; Montesinos, B.; Meeus, G.; Marshall, J. P.; Mendigutía, I.; Sandell, G.

    2016-02-01

    Herbig Ae/Be objects are pre-main sequence stars surrounded by gas- and dust-rich circumstellar discs. These objects are in the throes of star and planet formation, and their characterisation informs us of the processes and outcomes of planet formation processes around intermediate mass stars. Here we analyse the spectral energy distributions of disc host stars observed by the Herschel open time key programme "Gas in Protoplanetary Systems". We present Herschel/PACS far-infrared imaging observations of 22 Herbig Ae/Bes and 5 debris discs, combined with ancillary photometry spanning ultraviolet to sub-millimetre wavelengths. From these measurements we determine the diagnostics of disc evolution, along with the total excess, in three regimes spanning near-, mid-, and far-infrared wavelengths. Using appropriate statistical tests, these diagnostics are examined for correlations. We find that the far-infrared flux, where the disc becomes optically thin, is correlated with the millimetre flux, which provides a measure of the total dust mass. The ratio of far-infrared to sub-millimetre flux is found to be greater for targets with discs that are brighter at millimetre wavelengths and that have steeper sub-millimetre slopes. Furthermore, discs with flared geometry have, on average, larger excesses than flat geometry discs. Finally, we estimate the extents of these discs (or provide upper limits) from the observations. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  19. Paeoveitols A-E from Paeonia veitchii.

    PubMed

    Liang, Wen-Juan; Ma, Yun-Bao; Geng, Chang-An; Huang, Xiao-Yan; Xu, Hong-Bo; Zhang, Xue-Mei; Chen, Ji-Jun

    2015-10-01

    Paeoveitols A-E (1-5), involving three monoterpenes and two benzofuran constituents, were isolated from Paeonia veitchii. Their structures were determined based on extensive spectral analyses (IR, UV, MS, 1D and 2D NMR), and the absolute configuration of compound 1 was confirmed by single-crystal X-ray diffraction. By the agitating human melatonin receptor 1 (MT1) assay on HEK293 cell line in vitro, compound 4 showed weak activity with the agitation rate of 22.52% at the concentration of 1.79 mM.

  20. Chaotic appearance of the AE index

    NASA Technical Reports Server (NTRS)

    Shan, L.-H.; Hansen, P.; Goertz, C. K.; Smith, R. A.

    1991-01-01

    Results are reported from a stochastic analysis of a 5-day time series of the geomagnetic AE index during an active period. The original data, the power spectrum, and the autocorrelation function are shown, and the steps in the analysis are described in detail. It is found that the autocorrelation time scale is about 50 min, giving a correlation dimension (for the construction of a time series of m-dimensional vectors) of 2.4. This result is consistent with either colored-noise or deterministic-chaos magnetosphere models, indicating the need for further investigation.

  1. BOREAS AES READAC Surface Meteorological Data

    NASA Technical Reports Server (NTRS)

    Atkinson, G. Barrie; Funk, Barry; Hall, Forrest G. (Editor); Knapp, David E. (Editor)

    2000-01-01

    Canadian AES personnel collected and processed data related to surface atmospheric meteorological conditions over the BOREAS region. This data set contains 15-minute meteorological data from one READAC meteorology station in Hudson Bay, Saskatchewan. Parameters include day, time, type of report, sky condition, visibility, mean sea level pressure, temperature, dewpoint, wind, altimeter, opacity, minimum and maximum visibility, station pressure, minimum and maximum air temperature, a wind group, precipitation, and precipitation in the last hour. The data were collected non-continuously from 24-May-1994 to 20-Sep-1994. The data are provided in tabular ASCII files, and are classified as AFM-Staff data.

  2. BOREAS AES MARSII Surface Meteorological Data

    NASA Technical Reports Server (NTRS)

    Atkinson, G. Barrie; Funk, Barry; Hall, Forrest G. (Editor); Knapp, David E. (Editor)

    2000-01-01

    Canadian AES personnel collected several data sets related to surface and atmospheric meteorological conditions over the BOREAS region. This data set contains 15-minute meteorological data from six MARSII meteorology stations in the BOREAS region in Canada. Parameters include site, time, temperature, dewpoint, visibility, wind speed, wind gust, wind direction, two cloud groups, precipitation, and station pressure. Temporally, the data cover the period of May to September 1994. Geo-graphically, the stations are spread across the provinces of Saskatchewan and Manitoba. The data are provided in tabular ASCII files, and are classified as AFM-Staff data.

  3. AE measurements for evaluation of defects in FRP pressure vessels

    SciTech Connect

    Kawahara, Masanori; Takatsu, Takashi

    1995-11-01

    AE (acoustic emission) measurement was conducted in a series of pressuring tests of FRP pressure vessels in order to examine its applicability to the safety evaluation of vessels. Tested vessels were commercial FRP pressure vessels fabricated by filament winding of high strength glass fibers, impregnated epoxy resin, on a Al alloy liner. At the final stage of fabrication, they were subjected to autofrettage, an overpressuring treatment to produce compressive residual stresses in metal liner. AE measurement results showed a strong Kaiser`s effect and high felicity ratios. In a virgin vessel, very few AE signals were detected below the autofrettage pressure. Vessels containing artificial defects showed distinct increase in AE signals at the level of test pressure. AE origin map were obtained by triangular-zone calculation. Discussions are directed, in particular, to the selection of threshold and to the applicability of AE measurement to the in-service inspection of FRP pressure vessel.

  4. Energy efficiency analysis and implementation of AES on an FPGA

    NASA Astrophysics Data System (ADS)

    Kenney, David

    The Advanced Encryption Standard (AES) was developed by Joan Daemen and Vincent Rjimen and endorsed by the National Institute of Standards and Technology in 2001. It was designed to replace the aging Data Encryption Standard (DES) and be useful for a wide range of applications with varying throughput, area, power dissipation and energy consumption requirements. Field Programmable Gate Arrays (FPGAs) are flexible and reconfigurable integrated circuits that are useful for many different applications including the implementation of AES. Though they are highly flexible, FPGAs are often less efficient than Application Specific Integrated Circuits (ASICs); they tend to operate slower, take up more space and dissipate more power. There have been many FPGA AES implementations that focus on obtaining high throughput or low area usage, but very little research done in the area of low power or energy efficient FPGA based AES; in fact, it is rare for estimates on power dissipation to be made at all. This thesis presents a methodology to evaluate the energy efficiency of FPGA based AES designs and proposes a novel FPGA AES implementation which is highly flexible and energy efficient. The proposed methodology is implemented as part of a novel scripting tool, the AES Energy Analyzer, which is able to fully characterize the power dissipation and energy efficiency of FPGA based AES designs. Additionally, this thesis introduces a new FPGA power reduction technique called Opportunistic Combinational Operand Gating (OCOG) which is used in the proposed energy efficient implementation. The AES Energy Analyzer was able to estimate the power dissipation and energy efficiency of the proposed AES design during its most commonly performed operations. It was found that the proposed implementation consumes less energy per operation than any previous FPGA based AES implementations that included power estimations. Finally, the use of Opportunistic Combinational Operand Gating on an AES cipher

  5. BOREAS AES Campbell Scientific Surface Meteorological Data

    NASA Technical Reports Server (NTRS)

    Atkinson, G. Barrie; Funk, Barrie; Knapp. David E. (Editor); Hall, Forrest G. (Editor)

    2000-01-01

    Canadian AES personnel collected data related to surface and atmospheric meteorological conditions over the BOREAS region. This data set contains 15-minute meteorological data from 14 automated meteorology stations located across the BOREAS region. Included in this data are parameters of date, time, mean sea level pressure, station pressure, temperature, dew point, wind speed, resultant wind speed, resultant wind direction, peak wind, precipitation, maximum temperature in the last hour, minimum temperature in the last hour, pressure tendency, liquid precipitation in the last hour, relative humidity, precipitation from a weighing gauge, and snow depth. Temporally, the data cover the period of August 1993 to December 1996. The data are provided in tabular ASCII files, and are classified as AFM-Staff data.

  6. Multiple Lookup Table-Based AES Encryption Algorithm Implementation

    NASA Astrophysics Data System (ADS)

    Gong, Jin; Liu, Wenyi; Zhang, Huixin

    Anew AES (Advanced Encryption Standard) encryption algorithm implementation was proposed in this paper. It is based on five lookup tables, which are generated from S-box(the substitution table in AES). The obvious advantages are reducing the code-size, improving the implementation efficiency, and helping new learners to understand the AES encryption algorithm and GF(28) multiplication which are necessary to correctly implement AES[1]. This method can be applied on processors with word length 32 or above, FPGA and others. And correspondingly we can implement it by VHDL, Verilog, VB and other languages.

  7. Periodic Variations in DQ Herculis Stars

    NASA Astrophysics Data System (ADS)

    Bless, Robert

    1991-07-01

    The DQ Herculis Stars are cataclysmic variables showing rapid, strictly periodic luminosity variations at either optical or X-ray wavelengths, and usually both. The periods range from 33 sec in AE AQR through 71 sec in DQ Her to 18690 sec in TV Col. The cataclysmic variables are all close binary stars consisting of a late-type star transferring mass to its companion white dwarf star. The white dwarf in the DQ Her stars is magnetized. The periodicities of the DQ Her stars are caused by rotation of the magnetized, acreting white dwarf. We propose to observe the DQ Her stars at ultraviolet wavelengths using the high speed photometer on the space telescope. The purpose of the observations is to investigate the physics of accretion onto compact stars. Revision History: Prepared for future cycles submission--BJW 4/22/92; Cycle 3 to cycle 2, PRISM to SINGLE--BJW 8/27/92;

  8. Cardio-respiratory and subjective strains sustained by paraplegic subjects, when travelling on a cross slope in a manual wheelchair (MWC).

    PubMed

    Pierret, Benoît; Desbrosses, Kévin; Paysant, Jean; Meyer, Jean-Pierre

    2014-07-01

    The aim of this study was to quantify cardiac, energetic and subjective strains during manual wheelchair (MWC) travel on cross slopes (Cs). 25 paraplegics achieved eight 300 m propulsion tests combining 4 Cs (0, 2, 8 and 12%) and 2 velocities (Vi = 0.97 m s(-1), Vc "comfortable"). Heart rate and oxygen uptake were recorded continuously. Subjective rating (RPE) was made on completion of each test. Vc exceeds Vi for all Cs. Cardiac and energetic strains at Vc also exceed those at Vi (p < 0.01). Mean cardiac cost (in bpm) at Vc is 34 (SD = 13) bpm for a 0/2% Cs and 55 (18) bpm for a 12% Cs. Mean energetic cost (in J m(-1) kg(-1)) is 1.20 (0.38) and 2.76 (0.97) for respectively 0/2% and 12% Cs at Vi and, at Vc 1.50 (0.43) and 3.37 (1.43) for 0/2% and 12% Cs respectively. Subjective rating was considered as moderate for a 12% Cs. MWC users with high level injuries travel faster as those with low level injuries. Strain increase is linear for Cs from 0% to 12%. The results suggest that 2% Cs is generally acceptable, while 8% would be a critical threshold.

  9. A Grammar Sketch of the Kaki Ae Language.

    ERIC Educational Resources Information Center

    Clifton, John M.

    Kaki Ae is a non-Austronesian language spoken by about 300 people on the south coast of Papua New Guinea, at best distantly related to any other language in that area. A brief grammar sketch of the language is presented, including discussion of the phonology, sentences, phrases, words, and morpheme categories. Kaki Ae phonemics include 11…

  10. 15 CFR Appendix B to Part 30 - AES Filing Codes

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 15 Commerce and Foreign Trade 1 2013-01-01 2013-01-01 false AES Filing Codes B Appendix B to Part 30 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign Trade BUREAU OF THE CENSUS, DEPARTMENT OF COMMERCE FOREIGN TRADE REGULATIONS Pt. 30, App. B Appendix B to Part 30—AES Filing Codes Part...

  11. 15 CFR Appendix B to Part 30 - AES Filing Codes

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 15 Commerce and Foreign Trade 1 2012-01-01 2012-01-01 false AES Filing Codes B Appendix B to Part 30 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign Trade BUREAU OF THE CENSUS, DEPARTMENT OF COMMERCE FOREIGN TRADE REGULATIONS Pt. 30, App. B Appendix B to Part 30—AES Filing Codes Part...

  12. 15 CFR Appendix B to Part 30 - AES Filing Codes

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 15 Commerce and Foreign Trade 1 2014-01-01 2014-01-01 false AES Filing Codes B Appendix B to Part 30 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign Trade BUREAU OF THE CENSUS, DEPARTMENT OF COMMERCE FOREIGN TRADE REGULATIONS Pt. 30, App. B Appendix B to Part 30—AES Filing Codes Part...

  13. 15 CFR 758.2 - Automated Export System (AES).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 15 Commerce and Foreign Trade 2 2012-01-01 2012-01-01 false Automated Export System (AES). 758.2... CLEARANCE REQUIREMENTS § 758.2 Automated Export System (AES). The Census Bureau's Foreign Trade Statistics Regulations (FTSR) (15 CFR Part 30) contain provisions for filing Shipper's Export Declarations...

  14. 15 CFR 758.2 - Automated Export System (AES).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 15 Commerce and Foreign Trade 2 2011-01-01 2011-01-01 false Automated Export System (AES). 758.2... CLEARANCE REQUIREMENTS § 758.2 Automated Export System (AES). The Census Bureau's Foreign Trade Statistics Regulations (FTSR) (15 CFR part 30) contain provisions for filing Shipper's Export Declarations...

  15. 15 CFR 758.2 - Automated Export System (AES).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 15 Commerce and Foreign Trade 2 2013-01-01 2013-01-01 false Automated Export System (AES). 758.2... CLEARANCE REQUIREMENTS § 758.2 Automated Export System (AES). The Census Bureau's Foreign Trade Statistics Regulations (FTSR) (15 CFR Part 30) contain provisions for filing Shipper's Export Declarations...

  16. The global compendium of Aedes aegypti and Ae. albopictus occurrence.

    PubMed

    Kraemer, Moritz U G; Sinka, Marianne E; Duda, Kirsten A; Mylne, Adrian; Shearer, Freya M; Brady, Oliver J; Messina, Jane P; Barker, Christopher M; Moore, Chester G; Carvalho, Roberta G; Coelho, Giovanini E; Van Bortel, Wim; Hendrickx, Guy; Schaffner, Francis; Wint, G R William; Elyazar, Iqbal R F; Teng, Hwa-Jen; Hay, Simon I

    2015-01-01

    Aedes aegypti and Ae. albopictus are the main vectors transmitting dengue and chikungunya viruses. Despite being pathogens of global public health importance, knowledge of their vectors' global distribution remains patchy and sparse. A global geographic database of known occurrences of Ae. aegypti and Ae. albopictus between 1960 and 2014 was compiled. Herein we present the database, which comprises occurrence data linked to point or polygon locations, derived from peer-reviewed literature and unpublished studies including national entomological surveys and expert networks. We describe all data collection processes, as well as geo-positioning methods, database management and quality-control procedures. This is the first comprehensive global database of Ae. aegypti and Ae. albopictus occurrence, consisting of 19,930 and 22,137 geo-positioned occurrence records respectively. Both datasets can be used for a variety of mapping and spatial analyses of the vectors and, by inference, the diseases they transmit.

  17. Toward Understanding the B[e] Phenomenon: V. Nature and Spectral Variations of the MWC 728 Binary System.

    NASA Astrophysics Data System (ADS)

    Miroshnichenko, A. S.; Zharikov, S. V.; Danford, S.; Manset, N.; Korčáková, D.; Kříček, R.; Šlechta, M.; Omarov, Ch. T.; Kusakin, A. V.; Kuratov, K. S.; Grankin, K. N.

    2015-08-01

    We report the results of a long-term spectroscopic monitoring of the FS CMa type object MWC 728. We found that it is a binary system with a B5 ve ({T}{eff} = 14,000 ± 1000 K) primary and a G8 iii type ({T}{eff} ˜ 5000 K) secondary. Absorption line positions of the secondary vary, with a semi-amplitude of ˜20 km s-1 and a period of 27.5 days. The system’s mass function is 2.3 × 10-2 {M}⊙ , and its orbital plane is ˜13°-15° tilted from the plane of the sky. The primary’s v{sin}i˜ 110 km s-1, combined with this tilt, implies that it rotates at a nearly breakup velocity. We detected strong variations of the Balmer and He i emission-line profiles on timescales from days to years. This points to a variable stellar wind of the primary in addition to the presence of a circum-primary gaseous disk. The strength of the absorption-line spectrum, along with the optical and near infrared (IR) continuum, suggest that the primary contributes ˜60% of the V-band flux, the disk contributes ˜30%, and the secondary contributes ˜10%. The system parameters, along with the interstellar extinction, suggest a distance of ˜1 kpc, that the secondary does not fill its Roche lobe, and that the companions’ mass ratio is q ˜ 0.5. Overall, the observed spectral variability and the presence of a strong IR-excess are in agreement with a model of a close binary system that has undergone a non-conservative mass-transfer. of the Centre National de la Recherche Scientifique de France, and the University of Hawaii as well as on observations obtained at the 2.7 m Harlan J. Smith telescope of the McDonald Observatory (Texas, USA), 2.1 m of the Observatorio Astronomico Nacional San Pedro Martir (Baja California, Mexico), 2 m telescope of the Ondřejov Observatory, Czech Republic, and 0.81 m telescope of the Three College Observatory, North Carolina, USA.

  18. Roche tomography of cataclysmic variables - VII. The long-term magnetic activity of AE Aqr

    NASA Astrophysics Data System (ADS)

    Hill, C. A.; Watson, C. A.; Steeghs, D.; Dhillon, V. S.; Shahbaz, T.

    2016-06-01

    We present a long-term study of the secondary star in the cataclysmic variable AE Aqr, using Roche tomography to indirectly image starspots on the stellar surface spanning 8 years of observations. The seven maps show an abundance of spot features at both high and low latitudes. We find that all maps have at least one large high-latitude spot region, and we discuss its complex evolution between maps, as well as its compatibility with current dynamo theories. Furthermore, we see the apparent growth in fractional spot coverage, fs, around 45° latitude over the duration of observations, with a persistently high fs near latitudes of 20°. These bands of spots may form as part of a magnetic activity cycle, with magnetic flux tubes emerging at different latitudes, similar to the `butterfly' diagram for the Sun. We discuss the nature of flux tube emergence in close binaries, as well as the activity of AE Aqr in the context of other stars.

  19. IUE observations of new A star candidate proto-planetary systems

    NASA Technical Reports Server (NTRS)

    Grady, Carol A.

    1994-01-01

    As a result of the detection of accreting gas in the A5e PMS Herbig Ae star, HR 5999, most of the observations for this IUE program were devoted to Herbig Ae stars rather than to main sequence A stars. Mid-UV emission at optical minimum light was detected for UX Ori (A1e), BF Ori (A5e), and CQ Tau (F2e). The presence of accreting gas in HD 45677 and HD 50138 prompted reclassification of these stars as Herbig Be stars rather than as protoplanetary nebulae. Detailed results are discussed.

  20. Roche tomography of cataclysmic variables - VI. Differential rotation of AE Aqr - not tidally locked!

    NASA Astrophysics Data System (ADS)

    Hill, C. A.; Watson, C. A.; Shahbaz, T.; Steeghs, D.; Dhillon, V. S.

    2014-10-01

    We present Roche tomograms of the K4V secondary star in the cataclysmic variable AE Aqr, reconstructed from two data sets taken 9 d apart, and measure the differential rotation of the stellar surface. The tomograms show many large, cool starspots, including a large high-latitude spot and a prominent appendage down the trailing hemisphere. We find two distinct bands of spots around 22° and 43° latitude, and estimate a spot coverage of 15.4-17 per cent on the Northern hemisphere. Assuming a solar-like differential rotation law, the differential rotation of AE Aqr was measured using two different techniques. The first method yields an equator-pole lap time of 269 d and the second yields a lap time of 262 d. This shows that the star is not fully tidally locked, as was previously assumed for CVs, but has a co-rotation latitude of ˜40°. We discuss the implications that these observations have on stellar dynamo theory, as well as the impact that spot traversal across the L1 point may have on accretion rates in CVs as well as some of their other observed properties. The entropy landscape technique was applied to determine the system parameters of AE Aqr. For the two independent data sets, we find M1 = 1.20 and 1.17 M⊙, M2 = 0.81 and 0.78 M⊙, and orbital inclinations of 50° to 51° at optimal systemic velocities of γ = -64.7 and -62.9 km s-1.

  1. Gene flow between wheat and wild relatives: empirical evidence from Aegilops geniculata, Ae. neglecta and Ae. triuncialis.

    PubMed

    Arrigo, Nils; Guadagnuolo, Roberto; Lappe, Sylvain; Pasche, Sophie; Parisod, Christian; Felber, François

    2011-09-01

    Gene flow between domesticated species and their wild relatives is receiving growing attention. This study addressed introgression between wheat and natural populations of its wild relatives (Aegilops species). The sampling included 472 individuals, collected from 32 Mediterranean populations of three widespread Aegilops species (Aegilops geniculata, Ae. neglecta and Ae. triuncialis) and compared wheat field borders to areas isolated from agriculture. Individuals were characterized with amplified fragment length polymorphism fingerprinting, analysed through two computational approaches (i.e. Bayesian estimations of admixture and fuzzy clustering), and sequences marking wheat-specific insertions of transposable elements. With this combined approach, we detected substantial gene flow between wheat and Aegilops species. Specifically, Ae. neglecta and Ae. triuncialis showed significantly more admixed individuals close to wheat fields than in locations isolated from agriculture. In contrast, little evidence of gene flow was found in Ae. geniculata. Our results indicated that reproductive barriers have been regularly bypassed during the long history of sympatry between wheat and Aegilops.

  2. Gene flow between wheat and wild relatives: empirical evidence from Aegilops geniculata, Ae. neglecta and Ae. triuncialis

    PubMed Central

    Arrigo, Nils; Guadagnuolo, Roberto; Lappe, Sylvain; Pasche, Sophie; Parisod, Christian; Felber, François

    2011-01-01

    Gene flow between domesticated species and their wild relatives is receiving growing attention. This study addressed introgression between wheat and natural populations of its wild relatives (Aegilops species). The sampling included 472 individuals, collected from 32 Mediterranean populations of three widespread Aegilops species (Aegilops geniculata, Ae. neglecta and Ae. triuncialis) and compared wheat field borders to areas isolated from agriculture. Individuals were characterized with amplified fragment length polymorphism fingerprinting, analysed through two computational approaches (i.e. Bayesian estimations of admixture and fuzzy clustering), and sequences marking wheat-specific insertions of transposable elements. With this combined approach, we detected substantial gene flow between wheat and Aegilops species. Specifically, Ae. neglecta and Ae. triuncialis showed significantly more admixed individuals close to wheat fields than in locations isolated from agriculture. In contrast, little evidence of gene flow was found in Ae. geniculata. Our results indicated that reproductive barriers have been regularly bypassed during the long history of sympatry between wheat and Aegilops. PMID:25568015

  3. Cause of the exceptionally high AE average for 2003

    NASA Astrophysics Data System (ADS)

    Prestes, A.

    2012-04-01

    In this work we focus on the year of 2003 when the AE index was extremely high (AE=341nT, with peak intensity more than 2200nT), this value is almost 100 nT higher when compared with others years of the cycle 23. Interplanetary magnetic field (IMF) and plasma data are compared with geomagnetic AE and Dst indices to determine the causes of exceptionally high AE average value. Analyzing the solar wind parameters we found that the annual average speed value was extremely high, approximately 542 km/s (peak value ~1074 km/s). These values were due to recurrent high-speed solar streams from large coronal holes, which stretch to the solar equator, and low-latitude coronal holes, which exist for many solar rotations. AE was found to increase with increasing solar wind speed and decrease when solar wind speed decrease. The cause of the high AE activity during 2003 is the presence of the high-speed corotating streams that contain large-amplitude Alfvén waves throughout the streams, which resulted in a large number of HILDCAAs events. When plasma and field of solar wind impinge on Earth's magnetosphere, the southward field turnings associated with the wave fluctuations cause magnetic reconnection and consequential high levels of AE activity and very long recovery phases on Dst, sometimes lasting until the next stream arrives.

  4. Characterization of Aes nuclear foci in colorectal cancer cells.

    PubMed

    Itatani, Yoshiro; Sonoshita, Masahiro; Kakizaki, Fumihiko; Okawa, Katsuya; Stifani, Stefano; Itoh, Hideaki; Sakai, Yoshiharu; Taketo, M Mark

    2016-01-01

    Amino-terminal enhancer of split (Aes) is a member of Groucho/Transducin-like enhancer (TLE) family. Aes is a recently found metastasis suppressor of colorectal cancer (CRC) that inhibits Notch signalling, and forms nuclear foci together with TLE1. Although some Notch-associated proteins are known to form subnuclear bodies, little is known regarding the dynamics or functions of these structures. Here, we show that Aes nuclear foci in CRC observed under an electron microscope are in a rather amorphous structure, lacking surrounding membrane. Investigation of their behaviour during the cell cycle by time-lapse cinematography showed that Aes nuclear foci dissolve during mitosis and reassemble after completion of cytokinesis. We have also found that heat shock cognate 70 (HSC70) is an essential component of Aes foci. Pharmacological inhibition of the HSC70 ATPase activity with VER155008 reduces Aes focus formation. These results provide insight into the understanding of Aes-mediated inhibition of Notch signalling. PMID:26229111

  5. 22 CFR 120.30 - The Automated Export System (AES).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Commerce, Bureau of Census, electronic filing of export information. The AES shall serve as the primary... data and defense services shall be reported directly to the Directorate of Defense Trade Controls...

  6. Time Series Analysis and Prediction of AE and Dst Data

    NASA Astrophysics Data System (ADS)

    Takalo, J.; Lohikiski, R.; Timonen, J.; Lehtokangas, M.; Kaski, K.

    1996-12-01

    A new method to analyse the structure function has been constructed and used in the analysis of the AE time series for the years 1978-85 and Dst time series for 1957-84. The structure function (SF) was defined by S(l) = <|x(ti + lDt) - x(ti)|>, where Dt is the sampling time, l is an integer, and <|.|> denotes the average of absolute values. If a time series is self-affine its SF should scale for small values of l as S(l) is proportional to lH, where 0 < H < 1 is called the scaling exponent. It is known that for power-law (coloured) noise, which has P ~ f-a, a ~ 2H + 1 for 1 < a < 3. In this work the scaling exponent H was analysed by considering the local slopes dlog(S(l))/dlog(l) between two adjacent points as a function of l. For self-affine time series the local slopes should stay constant, at least for small values of l. The AE time series was found to be affine such that the scaling exponent changes at a time scale of 113 (+/-9) minutes. On the other hand, in the SF function analysis, the Dst data were dominated by the 24-hour and 27-day periods. The 27-day period was further modulated by the annual variation. These differences between the two time series arise from the difference in their periodicities in relation to their respective characteristic time scales. In the AE data the dominating periods are longer than that related to the characteristic time scale, i.e. they appear in the flatter part of the power spectrum. This is why the affinity is the dominating feature of the AE time series. In contrast with this the dominating periods of the Dst data are shorter than the characteristic time scale, and appear in the steeper part of the spectrum. Consequently periodicity is the dominating feature of the Dst data. Because of their different dynamic characteristics, prediction of Dst and AE time series appear to presuppose rather different approaches. In principle it is easier to produce the gross features of the Dst time series correctly as it is periodicity

  7. 22 CFR 120.30 - The Automated Export System (AES).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Commerce, Bureau of Census, electronic filing of export information. The AES shall serve as the primary...). Also, requests for special reporting may be made by DDTC on a case-by-case basis, (e.g.,...

  8. Effect of slurry mineralogy on slurry ICP-AES.

    PubMed

    Walker, C J; Davey, D E; Turner, K E; Hamilton, I C

    1996-07-01

    Direct slurry analysis by FI ICP-AES has been tested on seven iron-containing and five zinc-containing minerals. Results indicate that the method can be applied for traces and majors in a range of different materials.

  9. Preflight and Inflight Calibration of TES and AES

    NASA Technical Reports Server (NTRS)

    Rider, David M.

    1997-01-01

    The Thermal Emission Spectrometer (TES), an EOS CHEM platform instrument, and its companion instrument, the Airborne Emission Spectrometer (AES), are both Fourier transform spectrometers designed for remote sensing of the troposphere.

  10. Some performance tests of a microarea AES. [Auger Electron Spectroscopy

    NASA Technical Reports Server (NTRS)

    Todd, G.; Poppa, H.

    1978-01-01

    An Auger electron spectroscopy (AES) system which has a submicron analysis capability is described. The system provides secondary electron imaging, as well as micro- and macro-area AES. The resolution of the secondary electron image of an oxidized Al contact pad on a charge-coupled device chip indicates a primary beam size of about 1000 A. For Auger mapping, a useful resolution of about 4000 A is reported

  11. Oligomeric structure of bAE3 protein.

    PubMed

    Pushkin, A V; Tsuprun, V L; Abuladze, N K; Newman, D; Kurtz, I

    2000-12-01

    The "brain" form of the anion exchanger protein 3 (bAE3) has been purified to homogeneity from the rabbit kidney by differential centrifugation and immunoaffinity chromatography. A single protein band of approximately 165 kDa was detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. Monomers, dimers (a major component), and a higher oligomeric form (apparently tetramers) were found after oxidative cross-linking of purified bAE3. The largest form of bAE3 was separated from dimers and monomers by sucrose gradient centrifugation and was studied by transmission electron microscopy to confirm a tetrameric structure. Two main types of bAE3 images were detected, round (approximately 11-14 nm) and square-shaped (approximately 12 x 12 nm). Image analysis revealed fourfold rotational symmetry of both the round and square-shaped images, indicating that bAE3 consists of multiples of 4 subunits. We conclude that bAE3 in Triton X-100 solution is predominantly a mixture of dimers and tetramers with a smaller amount of monomers.

  12. Role of NBCe1 and AE2 in Secretory Ameloblasts

    PubMed Central

    Paine, Michael L.; Snead, Malcolm L.; Wang, HongJun; Abuladze, Natalia; Pushkin, Alexander; Liu, Weixin; Kao, Li Yo; Wall, Susan M.; Kim, Young-Hee; Kurtz, Ira

    2008-01-01

    The H+/base transport processes that control the pH of the microenvironment adjacent to ameloblasts are not currently well understood. Mice null for the AE2 anion exchanger have abnormal enamel. In addition, patients with mutations in the electrogenic sodium bicarbonate cotransporter NBCe1 and mice lacking NBCe1 have enamel abnormalities. These observations suggest that AE2 and NBCe1 play important roles in amelogenesis. The present study aimed to understand the roles of AE2 and NBC1 in ameloblasts. The data showed that NBCe1 is expressed at the basolateral membrane of secretory ameloblasts, whereas AE2 is expressed at the apical membrane. Transcripts for AE2a and NBCe1-B were detected in RNA isolated from cultured ameloblast-like LS8 cells. Our data are the first evidence that AE2 and NBCe1 are expressed in ameloblasts in vivo in a polarized fashion thereby providing a mechanism for ameloblast transcellular bicarbonate secretion in the process of enamel formation and maturation. PMID:18362326

  13. Evolutionary status of isolated B[e] stars

    NASA Astrophysics Data System (ADS)

    Lee, Chien-De; Chen, Wen-Ping; Liu, Sheng-Yuan

    2016-08-01

    Aims: We study a sample of eight B[e] stars with uncertain evolutionary status to shed light on the origin of their circumstellar dust. Methods: We performed a diagnostic analysis on the spectral energy distribution beyond infrared wavelengths, and conducted a census of neighboring region of each target to ascertain its evolutionary status. Results: In comparison to pre-main sequence Herbig stars, these B[e] stars show equally substantial excess emission in the near-infrared, indicative of existence of warm dust, but much reduced excess at longer wavelengths, so the dusty envelopes should be compact in size. Isolation from star-forming regions excludes the possibility of their pre-main sequence status. Six of our targets, including HD 50138, HD 45677, CD-24 5721, CD-49 3441, MWC 623, and HD 85567, have been previously considered as FS CMa stars, whereas HD 181615/6 and HD 98922 are added to the sample by this work. We argue that the circumstellar grains of these isolated B[e] stars, already evolved beyond the pre-main sequence phase, should be formed in situ. This is in contrast to Herbig stars, which inherit large grains from parental molecular clouds. It has been thought that HD 98922, in particular, is a Herbig star because of its large infrared excess, but we propose it being in a more evolved stage. Because dust condenses out of stellar mass loss in an inside-out manner, the dusty envelope is spatially confined, and anisotropic mass flows, or anomalous optical properties of tiny grains, lead to the generally low line-of-sight extinction toward these stars.

  14. Acoustic emissions (AE) during failure of granular media

    NASA Astrophysics Data System (ADS)

    Michlmayr, Gernot; Or, Dani

    2014-05-01

    The release of shallow landslides and other geological mass movements is the result of progressive failure accumulation. Mechanical failure in disordered geologic materials occurs in intermittent breakage episodes marking the disintegration or rearrangement of load-bearing elements. Abrupt strain energy release in such breakage episodes is associated with generation of elastic waves measurable as high-frequency (kHz range) acoustic emissions (AE). The close association of AE with progressive failure events hold a promise for using such noninvasive methods to assess the mechanical state of granular Earth materials or for the development early warning methods for shallow landslides. We present numerical simulations that incorporate damage accumulation and associated stress redistribution using a fiber-bundle model. The stress released from element failure (fibers) is redistributed to the surrounding elements and eventually triggers larger failure avalanches. AE signals generated from such events and eventually hitting a virtual sensor are modeled using visco-elastic wave propagation laws. The model captures the characteristic saw-tooth shape of the observed stress-strain curves obtained from strain-controlled experiments with glass beads, including large intermittent stress release events that stem from cascading failure avalanches. The model also reproduces characteristics of AE signatures and yield a good agreement between simulation results and experimental data. Linking mechanical and AE information in the proposed modeling framework offer a solid basis for interpretation of measured field data.

  15. Surface imaging of late-type contact binaries I: AE Phoenicis and YY Eridani

    NASA Astrophysics Data System (ADS)

    Maceroni, C.; Vilhu, O.; van't Veer, F.; van Hamme, W.

    1994-08-01

    This paper presents the results of the first application of Doppler Imaging to solar-type contact binaries. Our aim was to examine whether this technique can help discriminate between various types of surface inhomogeneities (dark vs. bright star-spots) which are produced by different physical processes and which affect not only the surface brightness distribution but also the system's secular evolution. Simultaneous high dispersion spectroscopy and photometry for the systems AE Phe and YY Eri were obtained at ESO using the Coude Auxiliary Telescope (CAT) and the 50 cm telescope. The observed light-curves were solved by means of the latest version of the Wilson-Devinney program. Doppler maps were constructed taking into account the effects of fast rotation and proximity of the system's components. Doppler maps reveal the presence of dark spots on both systems. For AE Phe, this result is in agreement with the light-curve solution. Indirect evidence of enhanced chromospheric emission is also found. This emission appears to be more intense on the primary components.

  16. Star Light, Star Bright.

    ERIC Educational Resources Information Center

    Iadevaia, David G.

    1984-01-01

    Presents a technique for obtaining a rough measure of the brightness among different stars. Materials needed include a standard 35-mm camera, a plastic ruler, and a photo enlarger. Although a telescope can be used, it is not essential. (JN)

  17. The FUSE satellite is prepped for prelaunch processing at Hangar AE, Cape Canaveral Air Station

    NASA Technical Reports Server (NTRS)

    1999-01-01

    At Hangar AE, Cape Canaveral Air Station, NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) satellite stands alone after workstands have been removed. As part of prelaunch processing, FUSE will undergo a functional test of its systems, followed by installation of the flight batteries and solar arrays. Tests are also scheduled for the communications and data systems linking FUSE with the spacecraft control center at The Johns Hopkins University, Baltimore, Md. FUSE was developed and will be operated by The Johns Hopkins University under contract to Goddard Space Flight Center, Greenbelt, Md. FUSE will investigate the origin and evolution of the lightest elements in the universe - hydrogen and deuterium. In addition, the FUSE satellite will examine the forces and process involved in the evolution of the galaxies, stars and planetary systems by investigating light in the far ultraviolet portion of the electromagnetic spectrum. The launch aboard a Boeing Delta II rocket is targeted for May 20 at Launch Complex 17.

  18. The FUSE satellite is prepped for prelaunch processing at Hangar AE, Cape Canaveral Air Station

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Workers in Hangar AE, Cape Canaveral Air Station, begin removing the plastic covering from NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) satellite before prelaunch processing. FUSE will undergo a functional test of its systems, followed by installation of the flight batteries and solar arrays. Tests are also scheduled for the communications and data systems linking FUSE with the spacecraft control center at The Johns Hopkins University, Baltimore, Md. FUSE was developed and will be operated by The Johns Hopkins University under contract to Goddard Space Flight Center, Greenbelt, Md. FUSE will investigate the origin and evolution of the lightest elements in the universe - hydrogen and deuterium. In addition, the FUSE satellite will examine the forces and process involved in the evolution of the galaxies, stars and planetary systems by investigating light in the far ultraviolet portion of the electromagnetic spectrum. The launch aboard a Boeing Delta II rocket is targeted for May 20 at Launch Complex 17.

  19. The FUSE satellite is prepped for prelaunch processing at Hangar AE, Cape Canaveral Air Station

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Workers in Hangar AE, Cape Canaveral Air Station, get ready to remove the protective shipping cover from NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) satellite for prelaunch processing. FUSE will undergo a functional test of its systems, followed by installation of the flight batteries and solar arrays. Tests are also scheduled for the communications and data systems linking FUSE with the spacecraft control center at The Johns Hopkins University, Baltimore, Md. FUSE was developed and will be operated by The Johns Hopkins University under contract to Goddard Space Flight Center, Greenbelt, Md. FUSE will investigate the origin and evolution of the lightest elements in the universe - hydrogen and deuterium. In addition, the FUSE satellite will examine the forces and process involved in the evolution of the galaxies, stars and planetary systems by investigating light in the far ultraviolet portion of the electromagnetic spectrum. The launch aboard a Boeing Delta II rocket is targeted for May 20 at Launch Complex 17.

  20. The FUSE satellite is prepped for prelaunch processing at Hangar AE, Cape Canaveral Air Station

    NASA Technical Reports Server (NTRS)

    1999-01-01

    At Hangar AE, Cape Canaveral Air Station, NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) satellite is unveiled before prelaunch processing. FUSE will undergo a functional test of its systems, followed by installation of the flight batteries and solar arrays. Tests are also scheduled for the communications and data systems linking FUSE with the spacecraft control center at The Johns Hopkins University, Baltimore, Md. FUSE was developed and will be operated by The Johns Hopkins University under contract to Goddard Space Flight Center, Greenbelt, Md. FUSE will investigate the origin and evolution of the lightest elements in the universe - hydrogen and deuterium. In addition, the FUSE satellite will examine the forces and process involved in the evolution of the galaxies, stars and planetary systems by investigating light in the far ultraviolet portion of the electromagnetic spectrum. The launch aboard a Boeing Delta II rocket is targeted for May 20 at Launch Complex 17.

  1. Scratching the itch: management of scabies in A&E.

    PubMed

    Hadfield-Law, L

    2000-10-01

    Epidemics of scabies seem to occur in 20-25-year cycles. One of the resultant problems is that few A&E nurses practice through more than one epidemic and with each new outbreak of scabies, the latest generation of A&E nurses have to learn how to recognize and manage the disease. This article describes scabies, how to recognize it and the treatment options available. Although uncertainty remains, Permethrin is the first treatment of choice and should be used in the 5% cream form, not the 100% lotion. Crusted Norwegian scabies requires prompt and careful attention along with Specialist advice. The challenge for A&E staff is to recognize scabies, treat it appropriately and to help educate those most at risk.

  2. Determination of AES Orbit Elements Using Mixed Data

    NASA Astrophysics Data System (ADS)

    Kolesnik, S. Ja.; Strakhova, S. L.

    An algorithm is worked out and a program is compiled for a determination of AES (artificial Earth satellite) orbit elements using both goniometrical and range-finder observations of different precision. The observations of one or several passages carried out from one or several stations can be used. A number of observational stations and a number of observations are not limited in principle. When solving this task the AES ephemerides on the moments of observations are calculated for different sets of orbit elements. A parameter F is considered which is a function of orbit elements. The parameter presents a square-mean deviation of AES ephemeris position on the moments {J;} from its observed one. The determination of real orbit elements comes to minimizing of parameter F by orbit elements using a method of deformed polyhedron. When calculating the ephemeris the amendments for 2-d, 3-d, 4-th geopotential zone harmonics are considered.

  3. An Improved Recovery Algorithm for Decayed AES Key Schedule Images

    NASA Astrophysics Data System (ADS)

    Tsow, Alex

    A practical algorithm that recovers AES key schedules from decayed memory images is presented. Halderman et al. [1] established this recovery capability, dubbed the cold-boot attack, as a serious vulnerability for several widespread software-based encryption packages. Our algorithm recovers AES-128 key schedules tens of millions of times faster than the original proof-of-concept release. In practice, it enables reliable recovery of key schedules at 70% decay, well over twice the decay capacity of previous methods. The algorithm is generalized to AES-256 and is empirically shown to recover 256-bit key schedules that have suffered 65% decay. When solutions are unique, the algorithm efficiently validates this property and outputs the solution for memory images decayed up to 60%.

  4. A high performance hardware implementation image encryption with AES algorithm

    NASA Astrophysics Data System (ADS)

    Farmani, Ali; Jafari, Mohamad; Miremadi, Seyed Sohrab

    2011-06-01

    This paper describes implementation of a high-speed encryption algorithm with high throughput for encrypting the image. Therefore, we select a highly secured symmetric key encryption algorithm AES(Advanced Encryption Standard), in order to increase the speed and throughput using pipeline technique in four stages, control unit based on logic gates, optimal design of multiplier blocks in mixcolumn phase and simultaneous production keys and rounds. Such procedure makes AES suitable for fast image encryption. Implementation of a 128-bit AES on FPGA of Altra company has been done and the results are as follow: throughput, 6 Gbps in 471MHz. The time of encrypting in tested image with 32*32 size is 1.15ms.

  5. Summary of detection, location, and characterization capabilities of AE for continuous monitoring of cracks in reactors

    SciTech Connect

    Hutton, P.H.; Kurtz, R.J.; Friesel, M.A.; Pappas, R.A.; Skorpik, J.R.; Dawson, J.F.

    1984-10-01

    The objective of the program is to develop acoustic emission (AE) methods for continuous monitoring of reactor pressure boundaries to detect and evaluate crack growth. The approach involves three phases: develop relationships to identify crack growth AE signals and to use identified crack growth AE data to estimate flaw severity; evaluate and refine AE/flaw relationships through fatigue testing a heavy section vessel under simulated reactor conditions; and demonstrate continuous AE monitoring on a nuclear power reactor system.

  6. Identification of a Novel HIV-1 Intra-CRF01_AE in China: A Descendant of the Previously Identified CRF01_AE transmission clusters 1 and 6

    PubMed Central

    Ning, Chuanyi; Li, Xingguang; Tang, Weiming; Zhou, Bo; Cai, Weiping; Tucker, Joseph D.

    2015-01-01

    We report here a novel HIV-1 intra-CRF01_AE recombinant form (CRF01-1AE/CRF01-6AE) composed of CRF01_AE transmission clusters 1 and 6, identified among heterosexuals in Fujian, with one breakpoint observed in vif gene. The CRF01_AE region I (HXB2: 868-5184) of the recombinant was clustered with the CRF01_AE transmission cluster 1, which is mainly circulating among IDUs and heterosexuals from the southern and southwestern China, with the support of 100% bootstrap value. The CRF01_AE region II (HXB2: 5185-9605) of the recombinant was clustered with the CRF01_AE transmission cluster 6, which is mainly prevailing among heterosexuals from southern China, with the support of 100% bootstrap value. To our best knowledge, this is the first detection of a novel HIV-1 intra-CRF01_AE recombinant form (CRF01-1_AE/CRF01-6_AE) in Fujian Province, which indicates ongoing active HIV-1 transmission among heterosexuals in this region. It may help illustrate CRF01_AE genetic diversity and contribute to our understanding of HIV-1 epidemiology, pathogenesis, and vaccine development. PMID:26100011

  7. Decision-making in A&E by expert nurses.

    PubMed

    Marsden, J

    The A&E service at Manchester Royal Eye Hospital uses triage as a method of prioritising patients to ensure that those whose needs are urgent receive immediate attention. The service has been extended to include formalised telephone triage. This study investigates the way in which telephone triage decisions are made by nurse practitioners in A&E. Although the sample is small, interviews with nurse practitioners reinforce previous theories about expert knowledge and decision-making. The practitioners use a process of hypothesis testing and a systematic and complex framework for decision-making.

  8. Gravity waves in the thermosphere observed by the AE satellites

    NASA Technical Reports Server (NTRS)

    Gross, S. H.; Reber, C. A.; Huang, F. T.

    1983-01-01

    Atmospheric Explorer (AE) satellite data were used to investigate the spectra characteristics of wave-like structure observed in the neutral and ionized components of the thermosphere. Power spectral analysis derived by the maximum entropy method indicate the existence of a broad spectrum of scale sizes for the fluctuations ranging from tens to thousands of kilometers.

  9. 19 CFR 192.11 - Description of the AES.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 30 of the Census Regulations (15 CFR part 30, subpart E), denominated Electronic Filing Requirements... TREASURY (CONTINUED) EXPORT CONTROL Filing of Export Information Through the Automated Export System (AES... commodity export information (see, 15 CFR 30.16) to submit such information electronically, rather than...

  10. 15 CFR 758.2 - Automated Export System (AES).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... that agency. See 15 CFR 30.62(b) of the FTSR. (b) BIS Option 4 application process. When AES filers... Regulations (FTSR) (15 CFR Part 30) contain provisions for filing Shipper's Export Declarations (SEDs... Census Bureau for certification and approval through a Letter of Intent (see 15 CFR 30.60(b) and...

  11. Supraphysiologic levels of the AML1-ETO isoform AE9a are essential for transformation.

    PubMed

    Link, Kevin A; Lin, Shan; Shrestha, Mahesh; Bowman, Melissa; Wunderlich, Mark; Bloomfield, Clara D; Huang, Gang; Mulloy, James C

    2016-08-01

    Chromosomal translocation 8;21 is found in 40% of the FAB M2 subtype of acute myeloid leukemia (AML). The resultant in-frame fusion protein AML1-ETO (AE) acts as an initiating oncogene for leukemia development. AE immortalizes human CD34(+) cord blood cells in long-term culture. We assessed the transforming properties of the alternatively spliced AE isoform AE9a (or alternative splicing at exon 9), which is fully transforming in a murine retroviral model, in human cord blood cells. Full activity was realized only upon increased fusion protein expression. This effect was recapitulated in the AE9a murine AML model. Cotransduction of AE and AE9a resulted in a strong selective pressure for AE-expressing cells. In the context of AE, AE9a did not show selection for increased expression, affirming observations of human t(8;21) patient samples where full-length AE is the dominant protein detected. Mechanistically, AE9a showed defective transcriptional regulation of AE target genes that was partially corrected at high expression. Together, these results bring an additional perspective to our understanding of AE function and highlight the contribution of oncogene expression level in t(8;21) experimental models. PMID:27457952

  12. Strange stars

    NASA Technical Reports Server (NTRS)

    Alcock, Charles; Farhi, Edward; Olinto, Angela

    1986-01-01

    Strange matter, a form of quark matter that is postulated to be absolute stable, may be the true ground stage of the hadrons. If this hypothesis is correct, neutron stars may convert to 'strange stars'. The mass-radius relation for strange stars is very different from that of neutron stars; there is no minimum mass, and for mass of 1 solar mass or less, mass is proportional to the cube of the radius. For masses between 1 solar mass and 2 solar masses, the radii of strange stars are about 10 km, as for neutron stars. Strange stars may have an exposed quark surface, which is capable of radiating at rates greatly exceeding the Eddington limit, but has a low emissivity for X-ray photons. The stars may have a thin crust with the same composition as the preneutron drip outer layer of a conventional neutron star crust. Strange stars cool efficiently via neutrino emission.

  13. Stars and Star Myths.

    ERIC Educational Resources Information Center

    Eason, Oliver

    Myths and tales from around the world about constellations and facts about stars in the constellations are presented. Most of the stories are from Greek and Roman mythology; however, a few Chinese, Japanese, Polynesian, Arabian, Jewish, and American Indian tales are also included. Following an introduction, myths are presented for the following 32…

  14. A Light Curve And Period Analysis Of AE Ursae Majoris, CY Aquarii, And DY Pegasi

    NASA Astrophysics Data System (ADS)

    Joner, Michael D.; Iverson, E. P.; Jolley, J. W.; Joner, L. A.; Swenson, C. A.

    2007-12-01

    We present a light curve analysis of three high amplitude delta Scuti stars (HADs). Data for this presentation were all secured during spring and fall of 2007. Most of the observations were obtained using the facilities of the Brigham Young University West Mountain Observatory. The variable stars we observed in this investigation include AE Ursae Majoris, CY Aquarii, and DY Pegasi. We present evidence for small period changes as well as an analysis of the light curve components for each of the variables. We compare the results obtained in the present investigation with prior studies of these same targets. This investigation is part of an initiative to provide a mentored learning environment at the West Mountain Observatory and to promote a variety of undergraduate research experiences. Tools developed in this investigation include the data reduction procedures that enable us to process the several thousand CCD frames that are secured each night as raw observations. We thank the Department of Physics and Astronomy and the College of Physical and Mathematical Sciences at Brigham Young University for the continued support of mentored undergraduate research.

  15. Resistance to cardiomyocyte hypertrophy in ae3 −/− mice, deficient in the AE3 Cl−/HCO3− exchanger

    PubMed Central

    2014-01-01

    Background Cardiac hypertrophy is central to the etiology of heart failure. Understanding the molecular pathways promoting cardiac hypertrophy may identify new targets for therapeutic intervention. Sodium-proton exchanger (NHE1) activity and expression levels in the heart are elevated in many models of hypertrophy through protein kinase C (PKC)/MAPK/ERK/p90RSK pathway stimulation. Sustained NHE1 activity, however, requires an acid-loading pathway. Evidence suggests that the Cl−/HCO3− exchanger, AE3, provides this acid load. Here we explored the role of AE3 in the hypertrophic growth cascade of cardiomyocytes. Methods AE3-deficient (ae3 −/− ) mice were compared to wildtype (WT) littermates to examine the role of AE3 protein in the development of cardiomyocyte hypertrophy. Mouse hearts were assessed by echocardiography. As well, responses of cultured cardiomyocytes to hypertrophic stimuli were measured. pH regulation capacity of ae3 −/− and WT cardiomyocytes was assessed in cultured cells loaded with the pH-sensitive dye, BCECF-AM. Results ae3 −/− mice were indistinguishable from wild type (WT) mice in terms of cardiovascular performance. Stimulation of ae3 −/− cardiomyocytes with hypertrophic agonists did not increase cardiac growth or reactivate the fetal gene program. ae3 −/− mice are thus protected from pro-hypertrophic stimulation. Steady state intracellular pH (pHi) in ae3 −/− cardiomyocytes was not significantly different from WT, but the rate of recovery of pHi from imposed alkalosis was significantly slower in ae3 −/− cardiomyocytes. Conclusions These data reveal the importance of AE3-mediated Cl−/HCO3− exchange in cardiovascular pH regulation and the development of cardiomyocyte hypertrophy. Pharmacological antagonism of AE3 is an attractive approach in the treatment of cardiac hypertrophy. PMID:25047106

  16. Differential inhibition of AE1 and AE2 anion exchangers by oxonol dyes and by novel polyaminosterol analogs of the shark antibiotic squalamine.

    PubMed

    Alper, S L; Chernova, M N; Williams, J; Zasloff, M; Law, F Y; Knauf, P A

    1998-01-01

    Oxonol and polyaminosterol drugs were examined as inhibitors of recombinant mouse AE1 and AE2 anion exchangers expressed in Xenopus laevis oocytes and were compared as inhibitors of AE1-mediated anion flux in red cells and in HL-60 cells that express AE2. The oxonols WW-781, diBA(5)C4, and diBA(3)C4 inhibited HL-60 cell Cl-/Cl- exchange with IC50 values from 1 to 7 microM, 100-1000 times less potent than their IC50 values for red cell Cl-/anion exchange. In Xenopus oocytes, diBA(5)C4 inhibited AE1-mediated Cl- efflux several hundred times more potently than that mediated by AE2. Several novel squalamine-related polyaminosterols were also evaluated as anion exchange inhibitors. In contrast to diBA(5)C4, polyaminosterol 1361 inhibited oocyte-expressed AE2 8-fold more potently than AE1 (IC50 0.6 versus 5.2 microM). The 3-fold less potent desulfo-analog, 1360, showed similar preference for AE2. It was found that 1361 also partially inhibited Cl- efflux from red cells, whereas neither polyaminosterol inhibited Cl efflux from HL60 cells. Thus, the oxonol diBA(5)C4 is >100-fold more potent as an inhibitor of AE1 than of AE2, whereas the polyaminosterols 1360 and 1361 are 8-fold more potent as inhibitors of AE2 than of AE1. Assay conditions and cell type influenced IC50 values for both classes of compounds. PMID:10353714

  17. New X-ray detections of Herbig stars

    NASA Astrophysics Data System (ADS)

    Stelzer, B.; Robrade, J.; Schmitt, J. H. M. M.; Bouvier, J.

    2009-01-01

    Context: The interpretation of X-ray detections from Herbig Ae/Be stars is disputed as it is not clear whether these intermediate-mass pre-main sequence stars are able to drive a dynamo and ensuing phenomena of magnetic activity. Alternative X-ray production mechanisms, related to stellar winds, star-disk magnetospheres, or unresolved late-type T Tauri star companions have been proposed. Aims: The companion hypothesis can be tested by resolving Herbig stars in X-rays from their known visual secondaries. Furthermore, their global X-ray properties (such as detection rate, luminosity, temperature, variability) may give clues to the emission mechanism by comparison to other types of stars, e.g. similar-age but lower-mass T Tauri stars, similar-mass but more evolved main-sequence A- and B-type stars, and with respect to model predictions. Methods: In a series of papers we have been investigating high-resolution X-ray Chandra images of Herbig Ae/Be and main-sequence B-type stars where known close visual companions are spatially separated from the primaries. Results: Here we report on six as yet unpublished Chandra exposures from our X-ray survey of Herbig stars. The target list comprises six Herbig stars with known cool companions, and three other A/B-type stars that are serendipitously in the Chandra field-of-view. In this sample we record a detection rate of 100%; i.e. all A/B-type stars display X-ray emission at levels of log(L_x/L_bol) ~ -5...-7. The analysis of hardness ratios confirms that HAeBes have hotter and/or more absorbed X-ray emitting plasma than more evolved B-type stars. Conclusions: Radiative winds are ruled out as an exclusive emission mechanism on the basis of the high X-ray temperatures. Confirming earlier results, the X-ray properties of Herbig Ae/Be stars are not vastly different from those of their late-type companion stars (if such are known). The diagnostics provided by the presently available data leave it open whether the hard X-ray emission

  18. Pulsating Stars

    NASA Astrophysics Data System (ADS)

    Catelan, M.; Smith, H. A.

    2015-03-01

    This book surveys our understanding of stars which change in brightness because they pulsate. Pulsating variable stars are keys to distance scales inside and beyond the Milky Way galaxy. They test our understanding not only of stellar pulsation theory but also of stellar structure and evolution theory. Moreover, pulsating stars are important probes of the formation and evolution of our own and neighboring galaxies. Our understanding of pulsating stars has greatly increased in recent years as large-scale surveys of pulsating stars in the Milky Way and other Local Group galaxies have provided a wealth of new observations and as space-based instruments have studied particular pulsating stars in unprecedented detail.

  19. Paediatric unplanned reattendance rate: A&E clinical quality indicators.

    PubMed

    O'Loughlin, Kate; Hacking, Katie A; Simmons, Naomi; Christian, William; Syahanee, R; Shamekh, Ahmed; Prince, Nicholas J

    2013-03-01

    The new accident and emergency (A&E) unplanned reattendance rate clinical quality indicator is intended to drive reduction of avoidable reattendances. Validation data for reattendance rates in children are awaited. The aim of this three site observational study is to establish the rate and reasons for unplanned reattendance to UK paediatric A&Es. Each centre undertook retrospective case note review of children attending at least twice within 7 days. Unplanned reattendance rates at the three centres were 5.1%, 5.2% and 4.4%. Reducing unnecessary unplanned reattendances is beneficial for patients, service capacity and efficacy. This study has identified two groups for targeting reattendance reduction: parents of children returning with the same diagnosis, severity unchanged and parents who bypass primary care resources. Clear communication and early involvement of experienced clinicians are paramount. This study has indicated that a 1%-5% unplanned reattendance rate is realistic, achievable and can drive improvement in children's services. PMID:23287643

  20. Paediatric unplanned reattendance rate: A&E clinical quality indicators.

    PubMed

    O'Loughlin, Kate; Hacking, Katie A; Simmons, Naomi; Christian, William; Syahanee, R; Shamekh, Ahmed; Prince, Nicholas J

    2013-03-01

    The new accident and emergency (A&E) unplanned reattendance rate clinical quality indicator is intended to drive reduction of avoidable reattendances. Validation data for reattendance rates in children are awaited. The aim of this three site observational study is to establish the rate and reasons for unplanned reattendance to UK paediatric A&Es. Each centre undertook retrospective case note review of children attending at least twice within 7 days. Unplanned reattendance rates at the three centres were 5.1%, 5.2% and 4.4%. Reducing unnecessary unplanned reattendances is beneficial for patients, service capacity and efficacy. This study has identified two groups for targeting reattendance reduction: parents of children returning with the same diagnosis, severity unchanged and parents who bypass primary care resources. Clear communication and early involvement of experienced clinicians are paramount. This study has indicated that a 1%-5% unplanned reattendance rate is realistic, achievable and can drive improvement in children's services.

  1. A Novel Byte-Substitution Architecture for the AES Cryptosystem

    PubMed Central

    Hossain, Fakir Sharif; Ali, Md. Liakot

    2015-01-01

    The performance of Advanced Encryption Standard (AES) mainly depends on speed, area and power. The S-box represents an important factor that affects the performance of AES on each of these factors. A number of techniques have been presented in the literature, which have attempted to improve the performance of the S-box byte-substitution. This paper proposes a new S-box architecture, defining it as ultra low power, robustly parallel and highly efficient in terms of area. The architecture is discussed for both CMOS and FPGA platforms, and the pipelined architecture of the proposed S-box is presented for further time savings and higher throughput along with higher hardware resources utilization. A performance analysis and comparison of the proposed architecture is also conducted with those achieved by the existing techniques. The results of the comparison verify the outperformance of the proposed architecture in terms of power, delay and size. PMID:26491967

  2. A Novel Byte-Substitution Architecture for the AES Cryptosystem.

    PubMed

    Hossain, Fakir Sharif; Ali, Md Liakot

    2015-01-01

    The performance of Advanced Encryption Standard (AES) mainly depends on speed, area and power. The S-box represents an important factor that affects the performance of AES on each of these factors. A number of techniques have been presented in the literature, which have attempted to improve the performance of the S-box byte-substitution. This paper proposes a new S-box architecture, defining it as ultra low power, robustly parallel and highly efficient in terms of area. The architecture is discussed for both CMOS and FPGA platforms, and the pipelined architecture of the proposed S-box is presented for further time savings and higher throughput along with higher hardware resources utilization. A performance analysis and comparison of the proposed architecture is also conducted with those achieved by the existing techniques. The results of the comparison verify the outperformance of the proposed architecture in terms of power, delay and size. PMID:26491967

  3. The circumstellar environments of intermediate mass main sequence stars

    NASA Technical Reports Server (NTRS)

    Grady, Carol A.

    1993-01-01

    Analysis of archival Infrared Astronomy Satellite (IRAS) and International Ultraviolet Explorer (IUE) data resulted in identification of accreting gas toward a 2.8 Myr post-Herbig Be star in the R CrA star formation region, and identification of accreting gas toward HD 93563, previously identified as a classical Be star. Accreting gas was also detected toward two B(e) stars of previously controversial evolutionary state, resulting in identification of these systems as pre-Main Sequence Herbig Be stars viewed edge-on to their circumstellar disks. In parallel with this effort, accreting gas was detected toward the Herbig Ae star HR 5999, resulting in development of identification criteria for edge-on PMS proto-planetary disk systems. The work on individual stars is described.

  4. Petchienes A-E, Meroterpenoids from Ganoderma petchii.

    PubMed

    Gao, Qin-Lei; Guo, Ping-Xia; Luo, Qi; Yan, Hui; Cheng, Yong-Xian

    2015-12-01

    Petchienes A-E (1-5), five new meroterpenoids, were isolated from the fruiting bodies of Ganoderma petchii. Their structures, including absolute configurations, were elucidated by means of spectroscopic and computational methods. Compound 4 was isolated as a racemic mixture, which was finally purified by chiral HPLC to yield individual (-) and (+)-antipodes. Biological evaluation showed that compounds 2 and (-)-4 could increase intracellular free calcium concentration at 10 μM in HEK-293 cells. PMID:26882654

  5. Compact and Secure Design of Masked AES S-Box

    NASA Astrophysics Data System (ADS)

    Zakeri, Babak; Salmasizadeh, Mahmoud; Moradi, Amir; Tabandeh, Mahmoud; Shalmani, Mohammad T. Manzuri

    Composite field arithmetic is known as an alternative method for lookup tables in implementation of S-box block of AES algorithm. The idea is to breakdown the computations to lower order fields and compute the inverse there. Recently this idea have been used both for reducing the area in implementation of S-boxes and masking implementations of AES algorithm. The most compact design using this technique is presented by Canright using only 92 gates for an S-box block. In another approach, IAIK laboratory has presented a masked implementation of AES algorithm with higher security comparing common masking methods using Composite field arithmetic. Our work in this paper is to use basic ideas of the two approaches above to get a compact masked S-box. We shall use the idea of masking inversion of IAIK's masked S-box but we will rewrite the equations using normal basis. We arrange the terms in these equations in a way that the optimized functions in Canright's compact S-box can be used for our design. An implementation of IAIK's masked S-box is also presented using Canright's polynomial functions to have a fair comparison between our design and IAIK's design. Moreover, we show that this design which uses two special normal basis for GF(16) and GF(4) is the smallest. We shall also prove the security of this design using some lemmas.

  6. 15 CFR 758.1 - The Shipper's Export Declaration (SED) or Automated Export System (AES) record.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...) or Automated Export System (AES) record. 758.1 Section 758.1 Commerce and Foreign Trade Regulations... (SED) or Automated Export System (AES) record. (a) The Shipper's Export Declaration (SED) or Automated Export System (AES) record. The SED (Form 7525-V, Form 7525-V-Alt, or Automated Export System record)...

  7. 15 CFR 758.1 - The Automated Export System (AES) record.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... CLEARANCE REQUIREMENTS § 758.1 The Automated Export System (AES) record. (a) The Shipper's Export Declaration (SED) or Automated Export System (AES) record. The SED (Form 7525-V, Form 7525-V-Alt, or Automated... AES record requirements. When an exemption from filing the Shipper's Export Declaration or...

  8. 15 CFR 758.1 - The Shipper's Export Declaration (SED) or Automated Export System (AES) record.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...) or Automated Export System (AES) record. 758.1 Section 758.1 Commerce and Foreign Trade Regulations... (SED) or Automated Export System (AES) record. (a) The Shipper's Export Declaration (SED) or Automated Export System (AES) record. The SED (Form 7525-V, Form 7525-V-Alt, or Automated Export System record)...

  9. 15 CFR 758.1 - The Shipper's Export Declaration (SED) or Automated Export System (AES) record.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...) or Automated Export System (AES) record. 758.1 Section 758.1 Commerce and Foreign Trade Regulations... (SED) or Automated Export System (AES) record. (a) The Shipper's Export Declaration (SED) or Automated Export System (AES) record. The SED (Form 7525-V, Form 7525-V-Alt, or Automated Export System record)...

  10. STAR System.

    ERIC Educational Resources Information Center

    Doverspike, James E.

    The STAR System is a developmental guidance approach to be used with elementary school children in the 5th or 6th grades. Two basic purposes underlie STAR: to increase learning potential and to enhance personal growth and development. STAR refers to 4 basic skills: sensory, thinking, adapting, and revising. Major components of the 4 skills are:…

  11. Massive Stars

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Villaver, Eva

    2009-11-01

    Participants; Preface Mario Livio and Eva Villaver; 1. High-mass star formation by gravitational collapse of massive cores M. R. Krumholz; 2. Observations of massive star formation N. A. Patel; 3. Massive star formation in the Galactic center D. F. Figer; 4. An X-ray tour of massive star-forming regions with Chandra L. K. Townsley; 5. Massive stars: feedback effects in the local universe M. S. Oey and C. J. Clarke; 6. The initial mass function in clusters B. G. Elmegreen; 7. Massive stars and star clusters in the Antennae galaxies B. C. Whitmore; 8. On the binarity of Eta Carinae T. R. Gull; 9. Parameters and winds of hot massive stars R. P. Kudritzki and M. A. Urbaneja; 10. Unraveling the Galaxy to find the first stars J. Tumlinson; 11. Optically observable zero-age main-sequence O stars N. R. Walborn; 12. Metallicity-dependent Wolf-Raynet winds P. A. Crowther; 13. Eruptive mass loss in very massive stars and Population III stars N. Smith; 14. From progenitor to afterlife R. A. Chevalier; 15. Pair-production supernovae: theory and observation E. Scannapieco; 16. Cosmic infrared background and Population III: an overview A. Kashlinsky.

  12. Hadron star models. [neutron stars

    NASA Technical Reports Server (NTRS)

    Cohen, J. M.; Boerner, G.

    1974-01-01

    The properties of fully relativistic rotating hadron star models are discussed using models based on recently developed equations of state. All of these stable neutron star models are bound with binding energies as high as about 25%. During hadron star formation, much of this energy will be released. The consequences, resulting from the release of this energy, are examined.

  13. Automatic Event Detection in Noisy Environment for Material Process Monitoring by Laser AE Method

    NASA Astrophysics Data System (ADS)

    Ito, K.; Kuriki, H.; Araki, H.; Kuroda, S.; Enoki, M.

    2014-06-01

    Laser acoustic emission (AE) method is a unique in-situ and non-contact nondestructive evaluation (NDE) method. It has a capability to detect signals generated from crack generation and propagation, friction and other physical phenomena in materials even in high temperature environment. However, laser AE system has lower signal-to-noise ratio compared to the conventional AE system using PZT sensors, so it is difficult to apply this method in noisy environment. A novel AE measurement system to detect events in such difficult environments was developed. This system could continuously record all AE waveforms and enable unrestricted post-analyses. Noise reduction filters in frequency domain coupling with a new AE event extraction using multiple threshold values showed a good potential for AE signal processing. This system was successfully applied for crack monitoring of plasma spray deposition process of ceramic coating.

  14. AES XPS study of chromium carbides and chromium iron carbides

    NASA Astrophysics Data System (ADS)

    Detroye, M.; Reniers, F.; Buess-Herman, C.; Vereecken, J.

    1999-04-01

    The nature of chromium rich carbides which precipitate at grain boundaries in steels is still not perfectly understood. We performed a multitechnique approach on model chromium carbide and chromium-iron carbide samples: Auger Electron Spectroscopy (AES), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), and High Energy Electron Diffraction (HEED) were used to characterise the samples. Significant chemical shifts were observed for the Cr, Fe and C XPS peaks in the M 7C 3 compound (M stands for metal), indicating unambiguously that the compound formed is a mixed iron-chromium carbide.

  15. Artificial epi-Retinal Prosthesis (AeRP)

    NASA Astrophysics Data System (ADS)

    Doorish, John F.

    2006-09-01

    There are several research projects going on around the world, which are attempting to develop a prosthetic device to restore sight to the blind. This paper describes the efforts of Second Sight of New York, Inc. The device being developed is called an Artificial epi-Retinal Prosthesis (AeRP), which is basically a small optical computer that fits into the intraocular space of the eye. The AeRP is designed to draw light into the device by specially designed fibre optics. The light is ‘digitized’ by the fibre optic system and then directed to individual photodiode cells making up concentric cylinders thus providing several hundred photodiode cells in the device. The produced electrical stimulation from each cell is then delivered to the retinal ganglion cells by a specially designed delivery system utilizing electrically conducting polymer strands (ECP), which sit on an ‘umbrella’ at the back of the device. The retinal ganglion cells receive the electrical stimulation, which would then be transmitted through the visual system of the brain. There are several innovations in this approach as compared to the other projects. They include, first the design, which will allow for a high number of PC to produce electrical stimulation that will stimulate multiple RGC per PC; the use of the ECP strands has not been used in such an approach before this. Tests have revealed that nerve cells have a good affinity for the material of the ECP. The use of the ECP as well as the fact that the AeRP is completely photovoltaic, with no external power sources, implies that there will not be high heat build-up in the back of the eye, which might damage RGC. A smaller version of the AeRP called the Mini epi-Retinal Prosthesis (MeRP) is the subject of a complimentary paper. It is being built now and will be tested in cell culture studies to determine the efficacy of the design and materials. No actual implants have been performed yet.

  16. Determination of the AES attitude from the angular velocity data

    NASA Astrophysics Data System (ADS)

    Eliasberg, P. E.; Pivovarov, M. L.

    1984-10-01

    A nonlinear algorithm that could be used for the AES satellite to determine its motions relative to its mass center using rate sensor data is presented. The calculations are performed relative to absolute geocentric and satellite body coordinate systems. A transfer matrix of cosines relates positions and velocities in one system to positions and velocities in the other. The orientation algorithm is obtained with a matrix kinematic equation solved by a least squares technique. Sample calculations for the Intercosmos 17 satellite, employing sun sensor and magnetometer data, show the algorithm's capabilities for generating the satellite variations in the orbital coordinate system. Yaw, roll and pitch data are obtained.

  17. Quantification of AES depth profiles by the MRI model

    NASA Astrophysics Data System (ADS)

    Kovač, Janez; Zalar, Anton; Praček, Borut

    2003-02-01

    The main physical effects that contribute to interface broadening in the sputter depth profiles of polycrystalline metallic multilayer structures were studied by comparison of measured and simulated AES depth profiles. An algorithm based on the so-called mixing-roughness-information depth (MRI) model was used to simulate AES depth profiles of Ni/Cr multilayer structures with different roughnesses of the initial surfaces. The simulated depth profiles were compared with measurements performed at two different depth profiling parameters on the Ni/Cr and Al/Ni/Cr multilayer structures with an initial surface roughness of about 1.0 and 21.5 nm, respectively. The comparison of simulated and measured depth profiles enabled us to separate and estimate different contributions to the interface broadening, as well as their dependence on the sputter depth. We found that roughness was the dominant factor related to depth resolution with respect to the information depth and atomic mixing contribution. The values of roughness introduced into the simulation algorithm coincided well with the values measured by AFM at the initial surface and after depth profiling. The results showed the capability of the simulation procedure based on the MRI model to separate and evaluate different contributions to the depth resolution.

  18. The anion exchanger Ae2 is required for enamel maturation in mouse teeth

    PubMed Central

    Lyaruu, DM; Bronckers, ALJJ; Mulder, L; Mardones, P; Medina, JF; Kellokumpu, S; Elferink, RPJ Oude; Everts, V

    2008-01-01

    One of the mechanisms by which epithelial cells regulate intracellular pH is exchanging bicarbonate for Cl−. We tested the hypothesis that in ameloblasts the anion exchanger-2 (Ae2) is involved in pH regulation during maturation stage amelogenesis. Quantitative X-ray microprobe mineral content analysis, scanning electron microscopy, histology, micro-computed tomography and Ae2 immuno-localisation analyses were applied to Ae2-deficient and wild-type mouse mandibles. Immuno-localisation of Ae2 in wild-type mouse incisors showed a very strong expression of Ae2 in the basolateral membranes of the maturation stage ameloblasts. Strikingly, zones of contiguous ameloblasts were found within the maturation stage in which Ae2 expression was extremely low as opposed to neighbouring cells. Maturation stage ameloblasts of the Ae2a,b−/− mice failed to stain for Ae2 and showed progressive disorganisation as enamel development advanced. Maturation stage enamel of the Ae2a,b−/− mice contained substantially less mineral and more protein than wild-type enamel as determined by quantitative X-ray microanalysis. Incisor enamel was more severely affected than molar enamel. Scanning electron microscopy revealed that the rod-inter-rod structures of the Ae2a,b−/− mice incisor enamel were absent. Mineral content of dentine and bone of Ae2a,b−/− mice was not significantly different from wild-type mice. The enamel from knockout mouse teeth wore down much faster than that from wild-type litter mates. Basolateral bicarbonate secretion via the anionic exchanger Ae2 is essential for mineral growth in the maturation stage enamel. The observed zonal expression of Ae2 in the maturation stage ameloblasts is in line with a model for cyclic proton secretion during maturation stage amelogenesis. PMID:18042363

  19. Transformation of AeIn4 Indides (Ae = Ba, Sr) into an AeAu2In2 Structure Type Through Gold Substitution

    SciTech Connect

    Dai, Jing-Cao; Corbett, John D.

    2007-04-17

    The title compounds were prepared from the elements by high-temperature solid-state synthesis techniques. X-ray structural analyses shows that BaAu{sub 2}In{sub 2} (1) and SrAu{sub 2}In{sub 2} (2) crystallize in a new orthorhombic structure, Pnma, Z = 4 (a = 8.755(2), 8.530(2) {angstrom}; b = 4.712(1), 4.598(1) {angstrom}; c = 12.368(3), 12.283(4) {angstrom}, respectively). Gold substitutes for 50% of the indium atoms in the tetragonal BaIn{sub 4} and monoclinic SrIn{sub 4} parents to give this new and more flexible orthorhombic structure. The Ae atoms in this structure are contained within chains of hexagonal prisms built of alternating In and Au that have additional augmenting atoms around their waists from further condensation of parallel displaced chains. The driving forces for these structural changes are in part the shorter Au-In distances (2.72 and 2.69 {angstrom}) relative to d(In-In) in the parents, presumably because of relativistic contractions with Au. Generalities about such centered prismatic building blocks and their condensation modes in these and related phases are described. Band structure calculations (EHTB) demonstrate that the two compounds are metallic, which is confirmed by measurements of the resistivity of 1 and the magnetic susceptibilities of both.

  20. Disc accretion in star forming regions

    NASA Astrophysics Data System (ADS)

    Kalari, V. M.

    2015-05-01

    In this thesis, I present new ultraviolet/optical/infrared photometric and spectroscopic observations of pre-main sequence stars that have formed in either metal-poor conditions, or in the vicinity of strong ionising radiation. This includes observations of 235 Classical T Tauri stars in the Lagoon Nebula; 63 Classical T Tauri/Herbig Ae stars in the Carina Nebula open cluster Trumpler 14; 24 intermediate mass T Tauri stars in the low-Z Sh 2-284 SFR; and one Herbig B[e] PMS candidate in the metal-poor 30 Doradus SFR. I measure the accretion rates of these PMS stars using the intensities of the U/Hα band excess measured through either optical spectra or imaging. Where possible, I use archive infrared photometry in the 1.2-8 micron wavelength range to measure the PMS disc evolutionary stage. The influence of the surrounding environment on the accretion rate evolution of pre-main sequence stars in these regions is explored using the spatial, and temporal distributions of accretion rate, mass, age and disc stage of PMS stars.

  1. The FUSE satellite is moved to a payload attach fitting in Hangar AE, Cape Canaveral Air Station

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Workers at Hangar AE, Cape Canaveral Air Station, maneuver an overhead crane toward NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) satellite standing between vertical workstands. The crane will lift FUSE to move it onto the Payload Attach Fitting (PAF) in front of it. FUSE is undergoing a functional test of its systems, plus installation of flight batteries and solar arrays. Developed by The Johns Hopkins University under contract to Goddard Space Flight Center, Greenbelt, Md., FUSE will investigate the origin and evolution of the lightest elements in the universe - hydrogen and deuterium. In addition, the FUSE satellite will examine the forces and process involved in the evolution of the galaxies, stars and planetary systems by investigating light in the far ultraviolet portion of the electromagnetic spectrum. FUSE is scheduled to be launched May 27 aboard a Boeing Delta II rocket at Launch Complex 17.

  2. The FUSE satellite is moved to a payload attach fitting in Hangar AE, Cape Canaveral Air Station

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Suspended by a crane in Hangar AE, Cape Canaveral Air Station, NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) satellite is lowered onto a circular Payload Attach Fitting (PAF). FUSE is undergoing a functional test of its systems, plus installation of flight batteries and solar arrays. Developed by The Johns Hopkins University under contract to Goddard Space Flight Center, Greenbelt, Md., FUSE will investigate the origin and evolution of the lightest elements in the universe - hydrogen and deuterium. In addition, the FUSE satellite will examine the forces and process involved in the evolution of the galaxies, stars and planetary systems by investigating light in the far ultraviolet portion of the electromagnetic spectrum. FUSE is scheduled to be launched May 27 aboard a Boeing Delta II rocket at Launch Complex 17.

  3. The FUSE satellite is moved to a payload attach fitting in Hangar AE, Cape Canaveral Air Station

    NASA Technical Reports Server (NTRS)

    1999-01-01

    While a crane lifts NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) satellite, workers at Hangar AE, Cape Canaveral Air Station, help guide it toward the circular Payload Attach Fitting (PAF) in front of it. FUSE is undergoing a functional test of its systems, plus installation of flight batteries and solar arrays. Developed by The Johns Hopkins University under contract to Goddard Space Flight Center, Greenbelt, Md., FUSE will investigate the origin and evolution of the lightest elements in the universe - hydrogen and deuterium. In addition, the FUSE satellite will examine the forces and process involved in the evolution of the galaxies, stars and planetary systems by investigating light in the far ultraviolet portion of the electromagnetic spectrum. FUSE is scheduled to be launched May 27 aboard a Boeing Delta II rocket at Launch Complex 17.

  4. Radio stars.

    PubMed

    Hjellming, R M; Wade, C M

    1971-09-17

    Up to the present time six classes of radio stars have been established. The signals are almost always very faint and drastically variable. Hence their discovery has owed as much to serendipity as to the highly sophisticated equipment and techniques that have been used. When the variations are regular, as with the pulsars, this characteristic can be exploited very successfully in the search for new objects as well as in the detailed study of those that are already known. The detection of the most erratically variable radio stars, the flare stars and the x-ray stars, is primarily a matter of luck and patience. In the case of the novas, one at least knows where and oughly when to look for radio emission. A very sensitive interferometer is clearly the best instrument to use in the initial detection of a radio star. The fact that weak background sources are frequently present makes it essential to prove that the position of a radio source agrees with that of a star to within a few arc seconds. The potential of radio astronomy for the study of radio stars will not be realized until more powerful instruments than those that are available today can be utilized. So far, we have been able to see only the most luminous of the radio stars. PMID:17836594

  5. Star Polymers.

    PubMed

    Ren, Jing M; McKenzie, Thomas G; Fu, Qiang; Wong, Edgar H H; Xu, Jiangtao; An, Zesheng; Shanmugam, Sivaprakash; Davis, Thomas P; Boyer, Cyrille; Qiao, Greg G

    2016-06-22

    Recent advances in controlled/living polymerization techniques and highly efficient coupling chemistries have enabled the facile synthesis of complex polymer architectures with controlled dimensions and functionality. As an example, star polymers consist of many linear polymers fused at a central point with a large number of chain end functionalities. Owing to this exclusive structure, star polymers exhibit some remarkable characteristics and properties unattainable by simple linear polymers. Hence, they constitute a unique class of technologically important nanomaterials that have been utilized or are currently under audition for many applications in life sciences and nanotechnologies. This article first provides a comprehensive summary of synthetic strategies towards star polymers, then reviews the latest developments in the synthesis and characterization methods of star macromolecules, and lastly outlines emerging applications and current commercial use of star-shaped polymers. The aim of this work is to promote star polymer research, generate new avenues of scientific investigation, and provide contemporary perspectives on chemical innovation that may expedite the commercialization of new star nanomaterials. We envision in the not-too-distant future star polymers will play an increasingly important role in materials science and nanotechnology in both academic and industrial settings.

  6. Radio stars.

    PubMed

    Hjellming, R M; Wade, C M

    1971-09-17

    Up to the present time six classes of radio stars have been established. The signals are almost always very faint and drastically variable. Hence their discovery has owed as much to serendipity as to the highly sophisticated equipment and techniques that have been used. When the variations are regular, as with the pulsars, this characteristic can be exploited very successfully in the search for new objects as well as in the detailed study of those that are already known. The detection of the most erratically variable radio stars, the flare stars and the x-ray stars, is primarily a matter of luck and patience. In the case of the novas, one at least knows where and oughly when to look for radio emission. A very sensitive interferometer is clearly the best instrument to use in the initial detection of a radio star. The fact that weak background sources are frequently present makes it essential to prove that the position of a radio source agrees with that of a star to within a few arc seconds. The potential of radio astronomy for the study of radio stars will not be realized until more powerful instruments than those that are available today can be utilized. So far, we have been able to see only the most luminous of the radio stars.

  7. On the evolution of the nova-like variable AE Aquarii

    NASA Astrophysics Data System (ADS)

    Meintjes, P. J.

    2002-10-01

    A possible evolution for the enigmatic cataclysmic variable AE Aquarii is considered that may put into context the long orbital period and short white dwarf rotation period compared with other DQ Her systems. It has been shown that mass transfer could have been initiated when the secondary KIV-V star was already somewhat evolved when it established Roche lobe contact. In this initial phase the orbital period of the system was probably Porb,i~ 8.5 h, and the white dwarf rotation period P*,i > 1 h. Mass transfer in the form of diamagnetic gas blobs will result in an initial discless accretion process, resulting in an efficient drain of the binary orbital angular momentum. Since the initial mass ratio of the binary was probably qi~ 0.8, a high mass transfer rate and a slow expansion of the Roche lobe of the secondary star followed, accompanied by a fast expanding secondary following the mass loss. This could have resulted in the KIV-V secondary flooding its Roche surface, causing a run-away mass transfer of that lasted for approximately , during which time the binary expanded to an orbital period of approximately Porb~ 11 h. During this phase the mass accretion rate on to the surface of the white dwarf most probably exceeded the critical value for stable nuclear burning , which could have resulted in AE Aqr turning into an ultrasoft X-ray source. The high mass transfer terminated when a critical mass ratio of qcrit= 0.73 was reached. Disc torques spun-up the white dwarf to a period close to 33 s within the time-scale before the high mass transfer shut down when qcrit was reached. The decrease in the mass loss of the secondary allowed it to re-establish hydrostatic equilibrium on the dynamical time-scale (fraction of a day). From this point when qcrit is reached the mass transfer and binary evolution proceed at a slower rate since mass transfer from the secondary star is driven by magnetic braking of the secondary on a time-scale , which is the same as the thermal time

  8. The use of the inner zone electron model AE-5 and associated computer programs

    NASA Technical Reports Server (NTRS)

    Teague, M. J.; Vette, J. I.

    1972-01-01

    A users guide to the inner radiation zone electron model AE-5 is introduced. The guide covers a description of the model, the forms in which it is available, directions on how to use the model, and a discussion of its limitations. Computer programs MODEL and ORP are described. These are major programs needed to use the electron models AE-4 and AE-5 and the smoothed proton models.

  9. A high voltage power supply for the AE-C and D low energy electron experiment

    NASA Technical Reports Server (NTRS)

    Gillis, J. A.

    1974-01-01

    A description is given of the electrical and mechanical design and operation of high voltage power supplies for space flight use. The supply was used to generate the spiraltron high voltage for low energy electron experiment on AE-C and D. Two versions of the supply were designed and built; one design is referred to as the low power version (AE-C) and the other as the high power version (AE-D). Performance is discussed under all operating conditions.

  10. NPS alternate techsat satellite, design project for AE-4871

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This project was completed as part of AE-4871, Advanced Spacecraft Design. The intent of the course is to provide experience in the design of all the major components in a spacecraft system. Team members were given responsibility for the design of one of the six primary subsystems: power, structures, propulsion, attitude control, telemetry, tracking and control (TT&C), and thermal control. In addition, a single member worked on configuration control, launch vehicle integration, and a spacecraft test plan. Given an eleven week time constraint, a preliminary design of each subsystem was completed. Where possible, possible component selections were also made. Assistance for this project came principally from the Naval Research Laboratory's Spacecraft Technology Branch. Specific information on components was solicited from representatives in industry. The design project centers on a general purpose satellite bus that is currently being sought by the Strategic Defense Initiative.

  11. Effects of Auger electron elastic scattering in quantitative AES

    NASA Astrophysics Data System (ADS)

    Jablonski, Aleksander

    1987-09-01

    The Monte Carlo algorithm was developed for simulating the trajectories of electrons elastically scattered in the solid. The distribution of scattering angles was determined using the partial wave expansion method. This algorithm was used to establish the influence of Auger electron elastic collisions on the results of quantitative AES analysis. The calculations were performed for the most pronounced KLL, L 3 MM and M 5NN Auger transitions. It turned out that due to the elastic collisions the Auger electron signal is decreased by up to 10%. The corresponding decreased of the escape depth of Auger electrons reaches 30% as compared with the value derived from the inelastic mean free path. The values of the inelastic mean free path resulting from the overalyer method may be strongly affected by elastic scattering of Auger electrons.

  12. Report on the Development of the Advanced Encryption Standard (AES).

    PubMed

    Nechvatal, J; Barker, E; Bassham, L; Burr, W; Dworkin, M; Foti, J; Roback, E

    2001-01-01

    In 1997, the National Institute of Standards and Technology (NIST) initiated a process to select a symmetric-key encryption algorithm to be used to protect sensitive (unclassified) Federal information in furtherance of NIST's statutory responsibilities. In 1998, NIST announced the acceptance of 15 candidate algorithms and requested the assistance of the cryptographic research community in analyzing the candidates. This analysis included an initial examination of the security and efficiency characteristics for each algorithm. NIST reviewed the results of this preliminary research and selected MARS, RC™, Rijndael, Serpent and Twofish as finalists. Having reviewed further public analysis of the finalists, NIST has decided to propose Rijndael as the Advanced Encryption Standard (AES). The research results and rationale for this selection are documented in this report. PMID:27500035

  13. Blindness Caused by Deficiency in AE3 Chloride/Bicarbonate Exchanger

    PubMed Central

    Alvarez, Bernardo V.; Gilmour, Gregory S.; Mema, Silvina C.; Martin, Brent T.; Shull, Gary E.; Casey, Joseph R.; Sauvé, Yves

    2007-01-01

    Background Vision is initiated by phototransduction in the outer retina by photoreceptors, whose high metabolic rate generates large CO2 loads. Inner retina cells then process the visual signal and CO2. The anion exchanger 3 gene (AE3/Slc4a3) encodes full-length AE3 (AE3fl) and cardiac AE3 (AE3c) isoforms, catalyzing plasma membrane Cl−/HCO3− exchange in Müller (AE3fl) and horizontal (AE3c) cells. AE3 thus maintains acid-balance by removing photoreceptor-generated CO2 waste. Methodology/Principal Findings We report that Slc4a3−/− null mice have inner retina defects (electroretinogram b-wave reduction, optic nerve and retinal vessel anomalies). These pathologic features are common to most human vitreoretinal degenerations. Immunobloting analysis revealed that Na+/HCO3− co-transporter (NBC1), and carbonic anhydrase II and CAXIV, protein expression were elevated in Slc4a3−/− mouse retinas, suggesting compensation for loss of AE3. TUNEL staining showed increased numbers of apoptotic nuclei from 4–6 months of age, in Slc4a3−/− mice, indicating late onset photoreceptor death. Conclusions/Significance Identification of Slc4a3 as underlying a previously unrecognized cause of blindness suggests this gene as a new candidate for a subset of hereditary vitreoretinal retinal degeneration. PMID:17786210

  14. Pre-Main-Sequence Star Candidates in the Bar of the Large Magellanic Cloud

    PubMed

    Beaulieu; Lamers; Grison; Julien; Lanciaux; Ferlet; Vidal-Madjar; Bertin; Maurice; Prevot; Gry; Guibert; Moreau; Tajhmady; Aubourg; Bareyre; de Kat J; Gros; Laurent; Lachieze-Rey; Lesquoy; Magneville; Milsztajn; Moscoso; Queinnec; Renault; Rich; Spiro; Vigroux; Zylberajch; Ansari; Cavalier; Moniez

    1996-05-17

    Candidate pre-main-sequence stars were observed in the bar of the Large Magellanic Cloud during the search for dark matter in the galactic halo. Seven blue stars of apparent visual magnitude 15 to 17 had irregular photometric variations and hydrogen emission lines in their optical spectra, which suggested that these stars are pre-main-sequence stars of about 10 solar masses. These stars are slightly more massive and definitely more luminous than are Herbig AeBe pre-main-sequence stars in our own galaxy. Continued observations of these very young stars from another galaxy, which are probably at the pre-hydrogen-burning stage, should provide important clues about early stages of star formation.

  15. Developments in heterobimetallic s-block systems: synthesis and structural survey of molecular M/Ae (M=Li, Na, K, Cs; Ae=Ca, Sr) aryloxo complexes.

    PubMed

    Zuniga, Maria Felisa; Deacon, Glen B; Ruhlandt-Senge, Karin

    2008-06-01

    A series of novel heterobimetallic group 1/strontium and group 1/calcium aryloxo complexes having the composition [MAe(Odpp)3] [Ae=Sr and M=Na (1), K (2, 3), Cs (4); Ae=Ca and M=Na (5), K (6), Cs (7)] or [M2Ae(Odpp)4] [M=Li and Ae=Sr (9), Ca (10)] have been prepared using 2,6-diphenylphenol (HOdpp) as the ligand. Through the use of solid-state direct metalation, these compounds were obtained either directly from the reaction vessel or after workup in toluene. The Lewis base adduct [KCa(Odpp)3(thf)] (8) was obtained by treatment of [KCa(Odpp)3] (6) with tetrahydrofuran (thf). All of the compounds displayed extensive metal-pi-arene interactions, which provide significant stabilization in these reactive species. The thermal stabilities and volatilities of representative heterobimetallic strontium and calcium complexes were investigated using thermogravimetric analysis.

  16. The Beta Pictoris Phenomenon in Young Stars With Accreting Gas

    NASA Technical Reports Server (NTRS)

    Grady, Carol A.

    1999-01-01

    Program Hae2BPIC resulted in usable ISO spectra of three young, Herbig Ae stars: HR 5999 (A7e, t=0.6 Myr), SV Cep (al-2e, t=1-3 Myr), and MW Vul (Al-2e, t=1-3 Myr). While too small a sample to pursue our original goal of surveying the silicate emission in these young, protoplanetary disk systems, comparison of these data with ground-based IR spectra, and published ISO observations of other HAe stars (especially the posters at PPIV) reveals the following: The known binary stars in the sample show signatures of partially crystal line silicate features by t=0.6 Myr, at an epoch when ostensibly single Herbig Ae stars have substantially stronger silicate emission dominated by amorphous grains. The known binary stars also show deficits in the optically thick continuum flux relative to coeval single stars. Comparison of ISO spectra indicates that the flux deficit seen in WD 163296 over 10-100 microns relative to AB Aur reflects a real deficit of material interior to 300.

  17. Chandra High-Energy Transmission Grating Spectrum of AE Aquarii

    NASA Astrophysics Data System (ADS)

    Mauche, Christopher W.

    2009-11-01

    The nova-like cataclysmic binary AE Aqr, which is currently understood to be a former supersoft X-ray binary and current magnetic propeller, was observed for over two binary orbits (78 ks) in 2005 August with the High-Energy Transmission Grating (HETG) on board the Chandra X-ray Observatory. The long, uninterrupted Chandra observation provides a wealth of details concerning the X-ray emission of AE Aqr, many of which are new and unique to the HETG. First, the X-ray spectrum is that of an optically thin multi-temperature thermal plasma; the X-ray emission lines are broad, with widths that increase with the line energy from σ ≈ 1 eV (510 km s-1) for O VIII to σ ≈ 5.5 eV (820 km s-1) for Si XIV; the X-ray spectrum is reasonably well fit by a plasma model with a Gaussian emission measure distribution that peaks at log T(K) = 7.16, has a width σ = 0.48, an Fe abundance equal to 0.44 times solar, and other metal (primarily Ne, Mg, and Si) abundances equal to 0.76 times solar; and for a distance d = 100 pc, the total emission measure EM = 8.0 × 1053 cm-3 and the 0.5-10 keV luminosity L X = 1.1 × 1031 erg s-1. Second, based on the f/(i + r) flux ratios of the forbidden (f), intercombination (i), and recombination (r) lines of the Heα triplets of N VI, O VII, and Ne IX measured by Itoh et al. in the XMM-Newton Reflection Grating Spectrometer spectrum and those of O VII, Ne IX, Mg XI, and Si XIII in the Chandra HETG spectrum, either the electron density of the plasma increases with temperature by over three orders of magnitude, from n e ≈ 6 × 1010 cm-3 for N VI [log T(K) ≈ 6] to n e ≈ 1 × 1014 cm-3 for Si XIII [log T(K) ≈ 7], and/or the plasma is significantly affected by photoexcitation. Third, the radial velocity of the X-ray emission lines varies on the white dwarf spin phase, with two oscillations per spin cycle and an amplitude K ≈ 160 km s-1. These results appear to be inconsistent with the recent models of Itoh et al., Ikhsanov, and Venter

  18. CHANDRA HIGH-ENERGY TRANSMISSION GRATING SPECTRUM OF AE AQUARII

    SciTech Connect

    Mauche, Christopher W.

    2009-11-20

    The nova-like cataclysmic binary AE Aqr, which is currently understood to be a former supersoft X-ray binary and current magnetic propeller, was observed for over two binary orbits (78 ks) in 2005 August with the High-Energy Transmission Grating (HETG) on board the Chandra X-ray Observatory. The long, uninterrupted Chandra observation provides a wealth of details concerning the X-ray emission of AE Aqr, many of which are new and unique to the HETG. First, the X-ray spectrum is that of an optically thin multi-temperature thermal plasma; the X-ray emission lines are broad, with widths that increase with the line energy from sigma approx 1 eV (510 km s{sup -1}) for O VIII to sigma approx 5.5 eV (820 km s{sup -1}) for Si XIV; the X-ray spectrum is reasonably well fit by a plasma model with a Gaussian emission measure distribution that peaks at log T(K) = 7.16, has a width sigma = 0.48, an Fe abundance equal to 0.44 times solar, and other metal (primarily Ne, Mg, and Si) abundances equal to 0.76 times solar; and for a distance d = 100 pc, the total emission measure EM = 8.0 x 10{sup 53} cm{sup -3} and the 0.5-10 keV luminosity L{sub X} = 1.1 x 10{sup 31} erg s{sup -1}. Second, based on the f/(i + r) flux ratios of the forbidden (f), intercombination (i), and recombination (r) lines of the Healpha triplets of N VI, O VII, and Ne IX measured by Itoh et al. in the XMM-Newton Reflection Grating Spectrometer spectrum and those of O VII, Ne IX, Mg XI, and Si XIII in the Chandra HETG spectrum, either the electron density of the plasma increases with temperature by over three orders of magnitude, from n {sub e} approx 6 x 10{sup 10} cm{sup -3} for N VI [log T(K) approx 6] to n {sub e} approx 1 x 10{sup 14} cm{sup -3} for Si XIII [log T(K) approx 7], and/or the plasma is significantly affected by photoexcitation. Third, the radial velocity of the X-ray emission lines varies on the white dwarf spin phase, with two oscillations per spin cycle and an amplitude K approx 160 km s

  19. Draft Genome Sequence of Brevibacterium linens AE038-8, an Extremely Arsenic-Resistant Bacterium

    SciTech Connect

    Maizel, Daniela; Utturkar, Sagar M.; Brown, Steven D.; Ferrero, Marcela; Rosen, Barry

    2015-04-16

    To understand the arsenic biogeocycles in the groundwaters at Tucumán, Argentina, we isolated Brevibacterium linens sp. strain AE38-8, obtained from arsenic-contaminated well water. This strain is extremely resistant to arsenicals and has arsenic resistance (ars) genes in its genome. Here, we report the draft genome sequence of B. linens AE38-8.

  20. 75 FR 7209 - Airworthiness Directives; Rolls-Royce Corporation (RRC) AE 3007A Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-18

    ... Directives; Rolls-Royce Corporation (RRC) AE 3007A Series Turbofan Engines AGENCY: Federal Aviation...: The FAA proposes to adopt a new airworthiness directive (AD) for RRC AE 3007A series turbofan engines... (ECIs) or surface wave ultrasonic testing (SWUT) inspections on high-pressure turbine (HPT) stage...

  1. STARS no star on Kauai

    SciTech Connect

    Jones, M.

    1993-04-01

    The island of Kuai, home to the Pacific Missile Range Facility, is preparing for the first of a series of Star Wars rocket launches expected to begin early this year. The Strategic Defense Initiative plans 40 launches of the Stategic Target System (STARS) over a 10-year period. The focus of the tests appears to be weapons and sensors designed to combat multiple-warhead ICBMs, which will be banned under the START II Treaty that was signed in January. The focus of this article is to express the dubious value of testing the STARS at a time when their application will not be an anticipated problem.

  2. ASCA X-ray observations of pre-main-sequence stars

    NASA Technical Reports Server (NTRS)

    Skinner, S. L.; Walter, F. M.; Yamauchi, S.

    1996-01-01

    The results of recent Advanced Satellite for Cosmology and Astrophysics (ASCA) X-ray observations of two pre-main sequence stars are presented: the weak emission line T Tauri star HD 142361, and the Herbig Ae star HD 104237. The solid state imaging spectrometer spectra for HD 142361 shows a clear emission line from H-like Mg 7, and spectral fits reveal a multiple temperature plasma with a hot component of at least 16 MK. The spectra of HD 104237 show a complex temperature structure with the hottest plasma at temperatures of greater than 30 MK. It is concluded that mechanisms that predict only soft X-ray emission can be dismissed for Herbig Ae stars.

  3. Universal quantification of elastic scattering effects in AES and XPS

    NASA Astrophysics Data System (ADS)

    Jablonski, Aleksander

    1996-09-01

    Elastic scattering of photoelectrons in a solid can be accounted for in the common formalism of XPS by introducing two correction factors, βeff and Qx. In the case of AES, only one correction factor, QA, is required. As recently shown, relatively simple analytical expressions for the correction factors can be derived from the kinetic Boltzmann equation within the so-called "transport approximation". The corrections are expressed here in terms of the ratio of the transport mean free path (TRMFP) to the inelastic mean free path (IMFP). Since the available data for the TRMFP are rather limited, it was decided to complete an extensive database of these values. They were calculated in the present work for the same elements and energies as in the IMFP tabulation published by Tanuma et al. An attempt has been made to derive a predictive formula providing the ratios of the TRMFP to the IMFP. Consequently, a very simple and accurate algorithm for calculating the correction factors βeff, Qx and QA has been developed. This algorithm can easily be generalized to multicomponent solids. The resulting values of the correction factors were found to compare very well with published values resulting from Monte Carlo calculations.

  4. Remarks on the definition of the backscattering factor in AES

    NASA Astrophysics Data System (ADS)

    Jablonski, Aleksander

    2002-03-01

    It has been shown that the backscattering factor in AES can be defined as an integral of the product of the excitation depth distribution function and the emission depth distribution function. First function describes the number of ionizations as a function of depth while the second function describes the escape probability of Auger electrons created at different depths. The backscattering factor calculated from such definition is found to depend on the Auger electron emission angle. For emission angles up to 40° with respect to surface normal, this dependence is not pronounced. However, influence of the emission angle on the backscattering factor may be substantial at glancing emission angles. Values of the backscattering factor calculated from the proposed algorithm assuming the emission angle equal to 40° differ noticeably from values resulting from the Shimizu expression. The deviation may reach 18% at primary electron energy of 2000 eV. Furthermore, the backscattering factor may become smaller than unity at primary energies close to the ionization energy. This effect has been suggested in earlier studies.

  5. Acoustic emission structural health management systems (AE-SHMS)

    NASA Astrophysics Data System (ADS)

    Finlayson, Richard D.; Friesel, Mark A.; Carlos, Mark F.; Miller, Ronnie K.; Godinez, Valery

    2000-05-01

    Many of today's methods of inspecting structures are very time consuming, labor intensive and in many cases (due to limited access), impractical. In addition, long shutdown times are required to perform the inspections, thus creating tremendous expenses associated with manpower, materials and lost production. With continuing advances in signal processing and communications a significant interest has been shown in developing new diagnostic technologies for monitoring the integrity of structures with known defects, or for detecting new defects, in real time with minimum human involvement. The continued use of aging structures, especially in regard to the airworthiness of aging aircraft, is a major area of concern. Recent developments in both active and passive Acoustic Emission monitoring as an advanced tool for 'Structural Health Management Systems (SHMS),' are illustrated by using two recently developed acoustic emission systems; the Acoustic Emission-Health and Usage Monitoring System (AE-HUMS) helicopter drivetrain health monitoring system, and the Acoustic Emission Flight Instrument System (AEFIS) composite health monitoring system. The data collected with these types of systems is processed with advanced data screening and classification techniques, which are employed to take full advantage of parametric and waveform-based acoustic emission.

  6. High-energy X-Ray Detection of G359.89-0.08 (Sgr A-E): Magnetic Flux Tube Emission Powered by Cosmic Rays?

    NASA Astrophysics Data System (ADS)

    Zhang, Shuo; Hailey, Charles J.; Baganoff, Frederick K.; Bauer, Franz E.; Boggs, Steven E.; Craig, William W.; Christensen, Finn E.; Gotthelf, Eric V.; Harrison, Fiona A.; Mori, Kaya; Nynka, Melania; Stern, Daniel; Tomsick, John A.; Zhang, William W.

    2014-03-01

    We report the first detection of high-energy X-ray (E > 10 keV) emission from the Galactic center non-thermal filament G359.89-0.08 (Sgr A-E) using data acquired with the Nuclear Spectroscopic Telescope Array (NuSTAR). The bright filament was detected up to ~50 keV during a NuSTAR Galactic center monitoring campaign. The featureless power-law spectrum with a photon index Γ ≈ 2.3 confirms a non-thermal emission mechanism. The observed flux in the 3-79 keV band is FX = (2.0 ± 0.1) × 10-12 erg cm-2 s-1, corresponding to an unabsorbed X-ray luminosity LX = (2.6 ± 0.8) × 1034 erg s-1 assuming a distance of 8.0 kpc. Based on theoretical predictions and observations, we conclude that Sgr A-E is unlikely to be a pulsar wind nebula (PWN) or supernova remnant-molecular cloud (SNR-MC) interaction, as previously hypothesized. Instead, the emission could be due to a magnetic flux tube which traps TeV electrons. We propose two possible TeV electron sources: old PWNe (up to ~100 kyr) with low surface brightness and radii up to ~30 pc or MCs illuminated by cosmic rays (CRs) from CR accelerators such as SNRs or Sgr A*.

  7. High-Energy X-Ray Detection of G359.89-0.08 (SGR A-E): Magnetic Flux Tube Emission Powered by Cosmic Rays?

    NASA Technical Reports Server (NTRS)

    Zhang, Shuo; Hailey, Charles J.; Baganoff, Frederick K.; Bauer, Franz E.; Boggs, Steven E.; Craig, William W.; Christensen, Finn E.; Gotthelf, Eric V.; Harrison, Fiona A.; Mori, Kaya; Nynka, Melania; Stern, Daniel; Tomsick, John A; Zhang, Will

    2014-01-01

    We report the first detection of high-energy X-ray (E (is) greater than 10 keV) emission from the Galactic center non-thermal filament G359.89-0.08 (Sgr A-E) using data acquired with the Nuclear Spectroscopic Telescope Array (NuSTAR). The bright filament was detected up to approximately 50 keV during a NuSTAR Galactic center monitoring campaign. The featureless power-law spectrum with a photon index gamma approximately equals 2.3 confirms a non-thermal emission mechanism. The observed flux in the 3-79 keV band is F(sub X) = (2.0 +/- 0.1) × 10(exp -12)erg cm(-2) s(-1) , corresponding to an unabsorbed X-ray luminosity L(sub X) = (2.6+/-0.8)×10(exp 34) erg s(-1) assuming a distance of 8.0 kpc. Based on theoretical predictions and observations, we conclude that Sgr A-E is unlikely to be a pulsar wind nebula (PWN) or supernova remnant-molecular cloud (SNR-MC) interaction, as previously hypothesized. Instead, the emission could be due to a magnetic flux tube which traps TeV electrons. We propose two possible TeV electron sources: old PWNe (up to (is) approximately 100 kyr) with low surface brightness and radii up to (is) approximately 30 pc or MCs illuminated by cosmic rays (CRs) from CR accelerators such as SNRs or Sgr A*.

  8. Cluster Chemistry in Electron-Poor Ae-Pt-Cd Systems (Ae=Ca, Sr, Ba): (Sr,Ba)Pt2Cd4, Ca6Pt8Cd16, and Its Known Antitype Er6Pd16Sb8

    SciTech Connect

    Samal, Saroj L.; Gulo, Fakhili; Corbett, John D.

    2013-02-18

    Three new ternary polar intermetallic compounds, cubic Ca6Pt8Cd16, and tetragonal (Sr, Ba)Pt2Cd4 have been discovered during explorations of the Ae–Pt–Cd systems. Cubic Ca6Pt8Cd16 (Fm-3m, Z = 4, a = 13.513(1) Å) contains a 3D array of separate Cd8 tetrahedral stars (TS) that are both face capped along the axes and diagonally bridged by Pt atoms to generate the 3D anionic network Cd8[Pt(1)]6/2[Pt(2)]4/8. The complementary cationic surface of the cell consists of a face-centered cube of Pt(3)@Ca6 octahedra. This structure is an ordered ternary variant of Sc11Ir4 (Sc6Ir8Sc16), a stuffed version of the close relative Na6Au7Cd16, and a network inverse of the recent Er6Sb8Pd16 (compare Ca6Pt8Cd16). The three groups of elements each occur in only one structural version. The new AePt2Cd4, Ae = Sr, Ba, are tetragonal (P42/mnm,Z = 2, a ≈ 8.30 Å, c ≈ 4.47 Å) and contain chains of edge-sharing Cd4 tetrahedra along c that are bridged by four-bonded Ba/Sr. LMTO-ASA and ICOHP calculation results and comparisons show that the major bonding (Hamilton) populations in Ca6Pt8Cd16 and Er6Sb8Pd16 come from polar Pt–Cd and Pd–Sb interactions, that Pt exhibits larger relativistic contributions than Pd, that characteristic size and orbital differences are most evident for Sb 5s, Pt8, and Pd16, and that some terms remain incomparable, Ca–Cd versus Er–Pd.

  9. On the infant weight loss of low- to intermediate-mass star clusters

    NASA Astrophysics Data System (ADS)

    Weidner, C.; Kroupa, P.; Nürnberger, D. E. A.; Sterzik, M. F.

    2007-04-01

    Star clusters are born in a highly compact configuration, typically with radii of less than about 1 pc roughly independently of mass. Since the star formation efficiency is less than 50 per cent by observation and because the residual gas is removed from the embedded cluster, the cluster must expand. In the process of doing so it only retains a fraction fst of its stars. To date there are no observational constraints for fst, although N-body calculations by Kroupa, Aarseth & Hurley suggest it to be about 20-30 per cent for Orion-type clusters. Here we use the data compiled by Testi et al., Testi, Palla & Natta and Testi, Palla & Natta for clusters around young Ae/Be stars and by de Wit et al. and de Wit et al. around young O stars and the study of de Zeeuw et al. of OB associations and combine these measurements with the expected number of stars in clusters with primary Ae/Be and O stars, respectively, using the empirical correlation between maximal stellar mass and star cluster mass of Weidner & Kroupa. We find that fst < 50 per cent with a decrease to higher cluster masses/more massive primaries. The interpretation would be that cluster formation is very disruptive. It appears that clusters with a birth stellar mass in the range 10-103Msolar keep at most 50 per cent of their stars.

  10. Ribosomal protein L7Ae is a subunit of archaeal RNase P.

    PubMed

    Cho, I-Ming; Lai, Lien B; Susanti, Dwi; Mukhopadhyay, Biswarup; Gopalan, Venkat

    2010-08-17

    To the mounting evidence of nonribosomal functions for ribosomal proteins, we now add L7Ae as a subunit of archaeal RNase P, a ribonucleoprotein (RNP) that catalyzes 5'-maturation of precursor tRNAs (pre-tRNAs). We first demonstrate that L7Ae coelutes with partially purified Methanococcus maripaludis (Mma) RNase P activity. After establishing in vitro reconstitution of the single RNA with four previously known protein subunits (POP5, RPP21, RPP29, and RPP30), we show that addition of L7Ae to this RNase P complex increases the optimal reaction temperature and k(cat)/K(m) (by approximately 360-fold) for pre-tRNA cleavage to those observed with partially purified native Mma RNase P. We identify in the Mma RNase P RNA a putative kink-turn (K-turn), the structural motif recognized by L7Ae. The large stimulatory effect of Mma L7Ae on RNase P activity decreases to Ae shown to be essential for K-turn binding. The critical, multifunctional role of archaeal L7Ae in RNPs acting in tRNA processing (RNase P), RNA modification (H/ACA, C/D snoRNPs), and translation (ribosomes), especially by employing the same RNA-recognition surface, suggests coevolution of various translation-related functions, presumably to facilitate their coordinate regulation. PMID:20675586

  11. Application of Normal Mode Expansion to AE Waves in Finite Plates

    NASA Technical Reports Server (NTRS)

    Gorman, M. R.; Prosser, W. H.

    1997-01-01

    Breckenridge et al. (1975), Hsu (1985) and Pao (1978) adapted approaches from seismology to calculate the response at the surface of an infinite half-space and an infinite plate. These approaches have found use in calibrating acoustic emission (AE) transducers. However, it is difficult to extend this theoretical approach to AE testing of practical structures. Weaver and Pao (1982) considered a normal mode solution to the Lamb equations. Hutchinson (1983) pointed out the potential relevance of Mindlin's plate theory (1951) to AE. Pao (1982) reviewed Medick s (1961) classical plate theory for a point source, but rejected it as useful for AE and no one seems to have investigated its relevance to AE any further. Herein, a normal mode solution to the classical plate bending equation was investigated for its applicability to AE. The same source-time function chosen by Weaver and Pao is considered. However, arbitrary source and receiver positions are chosen relative to the boundaries of the plate. This is another advantage of the plate theory treatment in addition to its simplicity. The source does not have to be at the center of the plate as in the axisymmetric treatment. The plate is allowed to remain finite and reflections are predicted. The importance of this theory to AE is that it can handle finite plates, realistic boundary conditions, and can be extended to composite materials.

  12. Physical parameter determination of seven RR Lyrae stars in Bootes

    NASA Astrophysics Data System (ADS)

    Peña, J. H.; Arellano, A.; Sareyan, J. P.; Peña, R.; Alvarez, M.

    2007-06-01

    uvbyβ photoelectric photometry of the RR Lyrae stars AE, RS, ST, TV, TW, UU, and XX Bootis has been acquired in order to determine the physical parameters of the stars. We used the correlation between the Fourier parameters derived from the light curves and the physical parameters such as the absolute magnitude M_v, intrinsic colour (B-V)_0 and metal abundance [Fe/H]. Once reddening has been determined, unreddened indices are obtained and T_{eff} and log g followed along the cycle, using a comparison with the theoretical models given for our determined metallicity.

  13. Monitoring Induced Seismicity with AE Sensors : The Influence of Unknown Calibration Functions

    NASA Astrophysics Data System (ADS)

    Plenkers, Katrin; Kwiatek, Grzegorz; Krüger, Frank

    2013-04-01

    We study the effect that an uncalibrated acoustic-emission (AE) sensor has on amplitude and magnitude using data of the JAGUARS project. The JAGUARS project recorded mining-induced seismicity in Mponeng Gold mine in Carletonville, South Africa in the frequency range 1 kHz < f < 180 kHz combining AE-sensors and accelerometers. Advanced monitoring of induced seismicity in underground structures sometimes includes today the use of high-frequency (f >> 1 kHz) AE monitoring systems. High-frequency monitoring allows the detection of seismic fractures on the centimeter scale and provides therefore important information about the migration of instabilities in the rock. Whereas the temporal-spatial analysis of seismic events recorded with AE sensors provides stable results, the analysis of source parameters including the estimation of magnitudes remains more challenging, because AE sensors are normally not well calibrated and exploit resonance frequencies to allow for high sensitivity. In our study the AE sensors are first calibrated in the frequency range 1kHz to 17 kHz relative to the well calibrated accelerometer. The calibration is possible due to the close employment of both sensor types, which allows to extract the sensor response (including the coupling effect) using signal deconvolution. We estimate three main resonance frequencies at about 2.5 kHz, 6 kHz and 10 kHz. Furthermore we calculate the directivity effect of the AE-sensor that influences the amplitude of the signal by up to - 15 dB. Second, we calculate the effect of the instrument response on the amplitude and the calculation of magnitude by studying synthetic data. We show the significant uncertainty that is introduced owing to the AE sensor response and conclude that source parameters often have high uncertainties and are not reliable for statistcal analsis if the instrument response of the recording AE sensor is not known.

  14. Global temperature constraints on Aedes aegypti and Ae. albopictus persistence and competence for dengue virus transmission

    PubMed Central

    2014-01-01

    Background Dengue is a disease that has undergone significant expansion over the past hundred years. Understanding what factors limit the distribution of transmission can be used to predict current and future limits to further dengue expansion. While not the only factor, temperature plays an important role in defining these limits. Previous attempts to analyse the effect of temperature on the geographic distribution of dengue have not considered its dynamic intra-annual and diurnal change and its cumulative effects on mosquito and virus populations. Methods Here we expand an existing modelling framework with new temperature-based relationships to model an index proportional to the basic reproductive number of the dengue virus. This model framework is combined with high spatial and temporal resolution global temperature data to model the effects of temperature on Aedes aegypti and Ae. albopictus persistence and competence for dengue virus transmission. Results Our model predicted areas where temperature is not expected to permit transmission and/or Aedes persistence throughout the year. By reanalysing existing experimental data our analysis indicates that Ae. albopictus, often considered a minor vector of dengue, has comparable rates of virus dissemination to its primary vector, Ae. aegypti, and when the longer lifespan of Ae. albopictus is considered its competence for dengue virus transmission far exceeds that of Ae. aegypti. Conclusions These results can be used to analyse the effects of temperature and other contributing factors on the expansion of dengue or its Aedes vectors. Our finding that Ae. albopictus has a greater capacity for dengue transmission than Ae. aegypti is contrary to current explanations for the comparative rarity of dengue transmission in established Ae. albopictus populations. This suggests that the limited capacity of Ae. albopictus to transmit DENV is more dependent on its ecology than vector competence. The recommendations, which we

  15. Automated Estimating System (AES): Version 6.1: User`s manual. Revision 6

    SciTech Connect

    Schwarz, R.K.; Holder, D.A.

    1996-03-01

    This document describes Version 6.1 of the Automated Estimating System (AES), a personal computer-based software package. The AES is designed to aid in the creation, updating, and reporting of project cost estimates for the Estimating and Scheduling Engineering Department of Central Engineering Services of Lockheed Martin Energy Systems,Inc. AES provides formatted input screens to guide the user through the estimate creation/update process and provides several standardized reports that allow cost to be sorted and summarized in many different formats and at several levels of aggregation.

  16. Application of TURBO-AE to Flutter Prediction: Aeroelastic Code Development

    NASA Technical Reports Server (NTRS)

    Hoyniak, Daniel; Simons, Todd A.; Stefko, George (Technical Monitor)

    2001-01-01

    The TURBO-AE program has been evaluated by comparing the obtained results to cascade rig data and to prediction made from various in-house programs. A high-speed fan cascade, a turbine cascade, a turbine cascade and a fan geometry that shower flutter in torsion mode were analyzed. The steady predictions for the high-speed fan cascade showed the TURBO-AE predictions to match in-house codes. However, the predictions did not match the measured blade surface data. Other researchers also reported similar disagreement with these data set. Unsteady runs for the fan configuration were not successful using TURBO-AE .

  17. Automated Estimating System (AES) version 6.0 - user`s manual. Revision 5

    SciTech Connect

    Holder, D.A.; Schwarz, R.K.

    1994-06-01

    This document describes Version 6.0 of the Automated Estimating System (AES), a personal computer-based software package. The AES is designed to aid in the creation, updating, and reporting of project cost estimates for the Estimating and Scheduling Engineering Department of Central Engineering Services of Martin Marietta Energy Systems, Inc. AES provides formatted input screens to guide the user through the estimate creation/update process and provides several standardized reports that allow cost to be sorted and summarized in many different formats and at several levels of aggregation.

  18. Physical parameters of seven field RR Lyrae Stars in bootes

    NASA Astrophysics Data System (ADS)

    Peña, J. H.; Arellano Ferro, A.; Peña Miller, R.; Sareyan, J. P.; Álvarez, M.

    2009-10-01

    Strömgren uvby-β photometry is reported for the RR Lyrae stars AE, RS, ST, TV, TW, UU, and XX in Bootes. The physical parameters M/M_⊙, log(L/L_⊙), M_V, log T_{eff} and [Fe/H], have been estimated from the Fourier decomposition of the light curves and the empirical calibrations developed for this type of stars. The obtained [Fe/H] values are compared with those calculated from the Δ S index for some sample stars. It was found that reddening in the zone is negligible compared to that shown by several objects in the same sky zone. From that, distance to the stars was calculated. The variation of the unreddened indexes (b-y)_0 and c_1 along the pulsational cycle allows the direct comparison with the theoretical grids and, hence, an independent determination of T_{eff} and log g.

  19. Star quality.

    PubMed

    Dent, Emma

    2007-09-20

    Around 150 wards are participating in the voluntary Star Wards scheme to provide mental health inpatients with more activities with therapeutic value. Suggested activities range from a library, to horse riding Internet access and comedy. Service users are particularly keen to have more exercise, which can be a challenge in inpatient settings. PMID:17970387

  20. Star Power

    ScienceCinema

    None

    2016-07-12

    The U.S. Department of Energy's Princeton Plasma Physics Laboratory has released ''Star Power,'' a new informational video that uses dramatic and beautiful images and thought-provoking interviews to highlight the importance of the Laboratory's research into magnetic fusion.

  1. Star Power

    SciTech Connect

    2014-10-17

    The U.S. Department of Energy's Princeton Plasma Physics Laboratory has released ''Star Power,'' a new informational video that uses dramatic and beautiful images and thought-provoking interviews to highlight the importance of the Laboratory's research into magnetic fusion.

  2. 12. PWD Drawing 10,0005(463AE1)(1936), 'Electrical Lighting and Power' Mare ...

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

    12. PWD Drawing 10,000-5(463A-E-1)(1936), 'Electrical Lighting and Power' - Mare Island Naval Shipyard, Battery Test Office & Storage Facility, California Avenue & E Street, Vallejo, Solano County, CA

  3. Time studies in A&E departments--a useful tool for management.

    PubMed

    Aharonson-Daniel, L; Fung, H; Hedley, A J

    1996-01-01

    A time and motion study was conducted in an accident and emergency (A&E) department in a Hong Kong Government hospital in order to suggest solutions for severe queuing problems found in A&E. The study provided useful information about the patterns of arrival and service; the throughput; and the factors that influence the length of the queue at the A&E department. Plans for building a computerized simulation model were dropped as new intelligence generated by the study enabled problem solving using simple statistical analysis and common sense. Demonstrates some potential benefits for management in applying operations research methods in busy clinical working environments. The implementation of the recommendations made by this study successfully eliminated queues in A&E.

  4. Propagation of Flexural Mode AE Signals in GR/EP Composite Plates

    NASA Technical Reports Server (NTRS)

    Prosser, W. H.; Gorman, M. R.

    1992-01-01

    It has been documented that AE signals propagate in thin plates as extensional and flexural plate modes. This was demonstrated using simulated AE sources (pencil lead breaks) by Gorman on thin aluminum and gr/ep composite plates and by Gorman and Prosser on thin aluminum plates. A typical signal from a pencil lead break source which identifies these two modes is shown. AE signals from transverse matrix cracking sources in gr/ep composite plates were also shown to propagate as plate modes by Gorman and Ziola. Smith showed that crack growth events in thin aluminum plates under spectrum fatigue loading produced signals that propagated as plate modes. Additionally, Prosser et al. showed that AE signals propagated as plate modes in a thin walled composite tube.

  5. Spectral Characteristics of Continuous Acoustic Emission (AE) Data from Laboratory Rock Deformation Experiments

    NASA Astrophysics Data System (ADS)

    Flynn, J. William; Goodfellow, Sebastian; Reyes-Montes, Juan; Nasseri, Farzine; Young, R. Paul

    2016-04-01

    Continuous acoustic emission (AE) data recorded during rock deformation tests facilitates the monitoring of fracture initiation and propagation due to applied stress changes. Changes in the frequency and energy content of AE waveforms have been previously observed and were associated with microcrack coalescence and the induction or mobilisation of large fractures which are naturally associated with larger amplitude AE events and lower-frequency components. The shift from high to low dominant frequency components during the late stages of the deformation experiment, as the rate of AE events increases and the sample approaches failure, indicates a transition from the micro-cracking to macro-cracking regime, where large cracks generated result in material failure. The objective of this study is to extract information on the fracturing process from the acoustic records around sample failure, where the fast occurrence of AE events does not allow for identification of individual AE events and phase arrivals. Standard AE event processing techniques are not suitable for extracting this information at these stages. Instead the observed changes in the frequency content of the continuous record can be used to characterise and investigate the fracture process at the stage of microcrack coalescence and sample failure. To analyse and characterise these changes, a detailed non-linear and non-stationary time-frequency analysis of the continuous waveform data is required. Empirical Mode Decomposition (EMD) and Hilbert Spectral Analysis (HSA) are two of the techniques used in this paper to analyse the acoustic records which provide a high-resolution temporal frequency distribution of the data. In this paper we present the results from our analysis of continuous AE data recorded during a laboratory triaxial deformation experiment using the combined EMD and HSA method.

  6. AE Geomagnetic Index Predictability for High Speed Solar Wind Streams: A Wavelet Decomposition Technique

    NASA Technical Reports Server (NTRS)

    Guarnieri, Fernando L.; Tsurutani, Bruce T.; Hajra, Rajkumar; Echer, Ezequiel; Gonzalez, Walter D.; Mannucci, Anthony J.

    2014-01-01

    High speed solar wind streams cause geomagnetic activity at Earth. In this study we have applied a wavelet interactive filtering and reconstruction technique on the solar wind magnetic field components and AE index series to allowed us to investigate the relationship between the two. The IMF Bz component was found as the most significant solar wind parameter responsible by the control of the AE activity. Assuming magnetic reconnection associated to southward directed Bz is the main mechanism transferring energy into the magnetosphere, we adjust parameters to forecast the AE index. The adjusted routine is able to forecast AE, based only on the Bz measured at the L1 Lagrangian point. This gives a prediction approximately 30-70 minutes in advance of the actual geomagnetic activity. The correlation coefficient between the observed AE data and the forecasted series reached values higher than 0.90. In some cases the forecast reproduced particularities observed in the signal very well.The high correlation values observed and the high efficacy of the forecasting can be taken as a confirmation that reconnection is the main physical mechanism responsible for the energy transfer during HILDCAAs. The study also shows that the IMF Bz component low frequencies are most important for AE prediction.

  7. Converting neutron stars into strange stars

    NASA Technical Reports Server (NTRS)

    Olinto, A. V.

    1991-01-01

    If strange matter is formed in the interior of a neutron star, it will convert the entire neutron star into a strange star. The proposed mechanisms are reviewed for strange matter seeding and the possible strange matter contamination of neutron star progenitors. The conversion process that follows seeding and the recent calculations of the conversion timescale are discussed.

  8. Transmembrane protein 139 (TMEM139) interacts with human kidney isoform of anion exchanger 1 (kAE1).

    PubMed

    Nuiplot, Nalin-On; Junking, Mutita; Duangtum, Natapol; Khunchai, Sasiprapa; Sawasdee, Nunghathai; Yenchitsomanus, Pa-Thai; Akkarapatumwong, Varaporn

    2015-08-01

    Human kidney anion exchanger 1 (kAE1) mediates Cl(-)/HCO3(-) exchanges at the basolateral membrane of the acid-secreting α-intercalated cells. Mutations in SLC4A1 gene encoding kAE1 are associated with distal renal tubular acidosis (dRTA). Several studies have shown that impaired trafficking of the mutant kAE1 is an important molecular mechanism underlying the pathogenesis of dRTA. Proteins involved in kAE1 trafficking were identified but the mechanism resulting in dRTA remained unclear. Thus, this study attempted to search for additional proteins interacting with C-terminal of kAE1 (Ct-kAE1) and involved in kAE1 trafficking to cell membrane. Transmembrane protein 139 (TMEM139) was identified as a protein interacting with Ct-kAE1 by yeast two-hybrid screening. The interaction between kAE1 and TMEM139 was confirmed by affinity co-purification, co-immunoprecipitation (co-IP) and yellow fluorescent protein (YFP)-based protein fragment complementation assay (PCA). In addition, flow cytometry results showed that suppression of endogenous TMEM139 by small interfering RNA (siRNA) and over-expression of TMEM139 in HEK293T cells could reduce and increase membrane localization of kAE1, respectively. The presented data demonstrate that TMEM139 interacts with kAE1 and promotes its intracellular trafficking. PMID:26049106

  9. Novel AE1 mutations in recessive distal renal tubular acidosis. Loss-of-function is rescued by glycophorin A.

    PubMed

    Tanphaichitr, V S; Sumboonnanonda, A; Ideguchi, H; Shayakul, C; Brugnara, C; Takao, M; Veerakul, G; Alper, S L

    1998-12-15

    The AE1 gene encodes band 3 Cl-/HCO3- exchangers that are expressed both in the erythrocyte and in the acid-secreting, type A intercalated cells of the kidney. Kidney AE1 contributes to urinary acidification by providing the major exit route for HCO3- across the basolateral membrane. Several AE1 mutations cosegregate with dominantly transmitted nonsyndromic renal tubular acidosis (dRTA). However, the modest degree of in vitro hypofunction exhibited by these dRTA-associated mutations fails to explain the disease phenotype in light of the normal urinary acidification associated with the complete loss-of-function exhibited by AE1 mutations linked to dominant spherocytosis. We report here novel AE1 mutations linked to a recessive syndrome of dRTA and hemolytic anemia in which red cell anion transport is normal. Both affected individuals were triply homozygous for two benign mutations M31T and K56E and for the loss-of-function mutation, G701D. AE1 G701D loss-of-function was accompanied by impaired trafficking to the Xenopus oocyte surface. Coexpression with AE1 G701D of the erythroid AE1 chaperonin, glycophorin A, rescued both AE1-mediated Cl- transport and AE1 surface expression in oocytes. The genetic and functional data both suggest that the homozygous AE1 G701D mutation causes recessively transmitted dRTA in this kindred with apparently normal erythroid anion transport. PMID:9854053

  10. Synthesis, Crystal and Electronic Structures of the Pnictides AE3TrPn3 (AE = Sr, Ba; Tr = Al, Ga; Pn = P, As)

    DOE PAGES

    Stoyko, Stanislav; Voss, Leonard; He, Hua; Bobev, Svilen

    2015-09-24

    New ternary arsenides AE3TrAs3 (AE = Sr, Ba; Tr = Al, Ga) and their phosphide analogs Sr3GaP3 and Ba3AlP3 have been prepared by reactions of the respective elements at high temperatures. Single-crystal X-ray diffraction studies reveal that Sr3AlAs3 and Ba3AlAs3 adopt the Ba3AlSb3-type structure (Pearson symbol oC56, space group Cmce, Z = 8). This structure is also realized for Sr3GaP3 and Ba3AlP3. Likewise, the compounds Sr3GaAs3 and Ba3GaAs3 crystallize with the Ba3GaSb3-type structure (Pearson symbol oP56, space group Pnma, Z = 8). Both structures are made up of isolated pairs of edge-shared AlPn4 and GaPn4 tetrahedra (Pn = pnictogen, i.e.,more » P or As), separated by the alkaline-earth Sr2+ and Ba2+ cations. In both cases, there are no homoatomic bonds, hence, regardless of the slightly different atomic arrangements, both structures can be rationalized as valence-precise [AE2+]3[Tr3+][Pn3-]3, or rather [AE2+]6[Tr2Pn6]12-, i.e., as Zintl phases.« less

  11. Exceptional Stars

    NASA Astrophysics Data System (ADS)

    Kulkarni, S. R.; Hansen, B.; van Kerkwijk, M.; Phinney, E. S.

    2005-12-01

    As part of our Interdisciplinary Scientist effort (PI, Kulkarni) for the Space Interferometry Mission (SIM) we proposed an investigation with SIM of a number of exceptional stars. With SIM we plan to observe dozens of nearby white dwarfs and search for planets surviving the evolution away from the main sequence as well as (newly formed) planets formed in the circumbinary disks of post-AGB binaries or as a result of white dwarf mergers. We propose to measure the proper motion of a sample of X-ray binaries and Be star binaries with the view of understanding the originof high latitude objects and inferring natal kicks and pre-supernova orbits. We plan to observe several compact object binaries to determine the mass of the compact star. Of particular importance is the proposed observation of SS 433 (for which we propose to use the spectrometer on SIM to measure the proper motion of the emission line clumps embedded in the relativistic jets). Separately we are investigating the issue of frame tie between SIM and the ecliptic frame (by observing binary millisecond pulsars with SIM; the position of these objects is very well determined by pulsar timing) and the degree to which highly precise visibility amplitude measurements can be inverted to infer binary parameters.

  12. Crustal stress, seismicity, acoustic emission (AE), and tectonics: the Kefallinì;a (Greece) case study

    NASA Astrophysics Data System (ADS)

    Gregori, G. P.; Poscolieri, M.; Paparo, G.; Ventrice, G.; de Simone, S.; Rafanelli, C.

    2009-04-01

    New inferences - confirming previous results (see references)- are presented dealing with a few years Acoustic Emission (AE) records collected at Kefallinìa (Ionian Islands, Greece). A physical distinction between HF (high frequency) vs. LF (low frequency) AE is required. Step-wise changes of the AE underground conductivity are evidenced, and can be suitably handled. "Smooth" results concern (i) the annual variation, (ii) some long-lasting stress "solitons" crossing through the area, and (iii) tidal effects. In particular, every AE station can be operated like a monitoring station both for Earth's tides and for the free oscillations of the Earth. In addition, Kefallinìa exhibits a much peculiar groundwater circulation, in which conduit flow is dominant, that originates a specific (and unique) AE effect. By means of AE time-series analysis, "extreme" or "catastrophic" events can be also monitored and possibly related to relevant tectonic occurrences (either earthquakes, or maybe other occasional phenomena). They can be investigated, and have a regional - rather than local - character. Therefore, every interpretation based on a single station record - being biased by some arbitrariness - can only result indicative. A standardized procedure and software is proposed for routine AE data handling and analysis. References.: Lagios et al., 2004. In Proc. SCI 2004 (The 8th World Multi-Conference on Systemics, Cybernetics and Informatic), Orlando, Florida, July 1004, 6 pp. Poscolieri et al., 2006. In. G. Cello and B. D. Malamud, (eds), 2006. Geol. Soc. London, Special Publ., 261, 63-78. Poscolieri et al., 2006a. Nat. Hazards Earth Syst. Sci., 6, 961-971.

  13. PETROLOGIC CONSTRAINTS ON AMORPHOUS AND CRYSTALLINE MAGNESIUM SILICATES: DUST FORMATION AND EVOLUTION IN SELECTED HERBIG Ae/Be SYSTEMS

    SciTech Connect

    Rietmeijer, Frans J. M.; Nuth, Joseph A.

    2013-07-01

    The Infrared Space Observatory, Spitzer Space Telescope, and Herschel Space Observatory surveys provided a wealth of data on the Mg-silicate minerals (forsterite, enstatite), silica, and ''amorphous silicates with olivine and pyroxene stoichiometry'' around Herbig Ae/Be stars. These incredible findings do not resonate with the mainstream Earth Sciences because of (1) disconnecting ''astronomical nomenclature'' and the long existing mineralogical and petrologic terminology of minerals and amorphous materials, and (2) the fact that Earth scientists (formerly geologists) are bound by the ''Principle of Actualism'' that was put forward by James Hutton (1726-1797). This principle takes a process-oriented approach to understanding mineral and rock formation and evolution. This paper will (1) review and summarize the results of laboratory-based vapor phase condensation and thermal annealing experiments, (2) present the pathways of magnesiosilica condensates to Mg-silicate mineral (forsterite, enstatite) formation and processing, and (3) present mineralogical and petrologic implications of the properties and compositions of the infrared-observed crystalline and amorphous dust for the state of circumstellar disk evolution. That is, the IR-observation of smectite layer silicates in HD142527 suggests the break-up of asteroid-like parent bodies that had experienced aqueous alteration. We discuss the persistence of amorphous dust around some young stars and an ultrafast amorphous to crystalline dust transition in HD 163296 that leads to forsterite grains with numerous silica inclusions. These dust evolution processes to form forsterite, enstatite {+-} tridymite could occur due to amorphous magnesiosilica dust precursors with a serpentine- or smectite-dehydroxylate composition.

  14. Petrologic Constraints on Amorphous and Crystalline Magnesium Silicates: Dust Formation and Evolution in Selected Herbig Ae/Be Systems

    NASA Astrophysics Data System (ADS)

    Rietmeijer, Frans J. M.; Nuth, Joseph A.

    2013-07-01

    The Infrared Space Observatory, Spitzer Space Telescope, and Herschel Space Observatory surveys provided a wealth of data on the Mg-silicate minerals (forsterite, enstatite), silica, and "amorphous silicates with olivine and pyroxene stoichiometry" around Herbig Ae/Be stars. These incredible findings do not resonate with the mainstream Earth Sciences because of (1) disconnecting "astronomical nomenclature" and the long existing mineralogical and petrologic terminology of minerals and amorphous materials, and (2) the fact that Earth scientists (formerly geologists) are bound by the "Principle of Actualism" that was put forward by James Hutton (1726-1797). This principle takes a process-oriented approach to understanding mineral and rock formation and evolution. This paper will (1) review and summarize the results of laboratory-based vapor phase condensation and thermal annealing experiments, (2) present the pathways of magnesiosilica condensates to Mg-silicate mineral (forsterite, enstatite) formation and processing, and (3) present mineralogical and petrologic implications of the properties and compositions of the infrared-observed crystalline and amorphous dust for the state of circumstellar disk evolution. That is, the IR-observation of smectite layer silicates in HD142527 suggests the break-up of asteroid-like parent bodies that had experienced aqueous alteration. We discuss the persistence of amorphous dust around some young stars and an ultrafast amorphous to crystalline dust transition in HD 163296 that leads to forsterite grains with numerous silica inclusions. These dust evolution processes to form forsterite, enstatite ± tridymite could occur due to amorphous magnesiosilica dust precursors with a serpentine- or smectite-dehydroxylate composition.

  15. Molecular hydrogen emission from the Cepheus A star-formation region

    SciTech Connect

    Doyon, R.; Nadeau, D.

    1988-11-01

    Fabry-Perot spectrometry of H2 emission lines in the Cepheus A star-formation region is presented. It is found that the H2 emission in Cep A(E) is associated with dense condensations of NH3 and CS, while the emission in Cep A(W) is associated with Herbig-Haro objects and reflection nebulae. The data support the hypothesis that the two lobes of emission are produced by a single outflow originating from the region of maser and compact H II regions at the western edge of Cep A(E). 49 references.

  16. Binary stars.

    PubMed

    Paczynacuteski, B

    1984-07-20

    Most stars in the solar neighborhood are either double or multiple systems. They provide a unique opportunity to measure stellar masses and radii and to study many interesting and important phenomena. The best candidates for black holes are compact massive components of two x-ray binaries: Cygnus X-1 and LMC X-3. The binary radio pulsar PSR 1913 + 16 provides the best available evidence for gravitational radiation. Accretion disks and jets observed in close binaries offer a very good testing ground for models of active galactic nuclei and quasars.

  17. Binary stars.

    PubMed

    Paczynacuteski, B

    1984-07-20

    Most stars in the solar neighborhood are either double or multiple systems. They provide a unique opportunity to measure stellar masses and radii and to study many interesting and important phenomena. The best candidates for black holes are compact massive components of two x-ray binaries: Cygnus X-1 and LMC X-3. The binary radio pulsar PSR 1913 + 16 provides the best available evidence for gravitational radiation. Accretion disks and jets observed in close binaries offer a very good testing ground for models of active galactic nuclei and quasars. PMID:17749544

  18. Narrow-band Imagery with the Goddard Fabry-Perot: Probing the Epoch of Active Accretion for PMS Stars

    NASA Technical Reports Server (NTRS)

    Woodgate, Bruce E.; Grady, C.; Endres, M.; Williger, G.

    2006-01-01

    The STIS coronagraphic imaging sample of I'MS stars was surveyed with the Goddard Fabry-Perot (GFP) interferometer to determine what fraction of the stars drive jets, whether there is any difference in behavior for a group of intermediate-mass stars as compared with T Tauri stars, and to search for evolutionary effects. Compared to broad band imaging, the FGP achieves an emission-line nebulosity-to-star contrast gain of between 500 and 3000. To date, we have detected jets associated with classical T Tauri stars spanning a factor of 280 in mass accretion rate in approximately 50% of the STIS coronagraphic imaging sample. We also detected jets or Herbig-HARO knots associated with 5 Herbig Ae stars, all younger than 8 Myr, for a detection fraction which is smaller than the T Tauri survey.

  19. Search for gamma-ray emissions from AE Aquarii with Fermi LAT

    NASA Astrophysics Data System (ADS)

    Li, Jian; Rea, Nanda; De Ona Wilhelmi, Emma; Torres, Diego F.; Hou, Xian

    2016-07-01

    AE Aquarii is a cataclysmic variable with the fastest known rotating magnetized white dwarf (P_{spin} = 33.08 s). We report on deep searches for gamma-ray emission and pulsations from AE Aquarii in seven years of Fermi-LAT Pass 8 data. Using different X-ray observations spanning 20 years, we substantially extended the timing ephemeris of AE Aquarii. A spin phase jump was discovered between MJD 55122.5 - 56078.64 by X-ray timing analysis. Using the extended timing ephemeris, we searched for gamma-ray pulsations at the spin period and its first harmonic. No gamma-ray pulsation were detected above 3 sigma significance. Neither steady gamma-ray emission nor gamma-ray variability of AE Aquarii were detected by Fermi-LAT. We impose the most restrictive upper limit on the gamma-ray emission from AE Aquarii to date, as 1.23×10^{-12} erg cm^{-2} s^{-1} in 0.1-300 GeV range providing constrains on models.

  20. Organizing for empowerment: an interview with AES's Roger Sant and Dennis Bakke. Interview by Suzy Wetlaufer.

    PubMed

    Sant, R; Bakke, D

    1999-01-01

    The topic of empowerment is receiving a lot of attention, but how many employees are truly empowered? At the global electricity giant AES Corporation, the answer is all 40,000 of them. In this interview, chairman Roger Sant and CEO Dennis Bakke reflect on their trials and triumphs in creating an exceptional company and explain how their employee-run company works. When they founded AES in 1981, Sant and Bakke set out to create a company where people could have engaging experiences on a daily basis--a company that embodied the principles of fairness, integrity, social responsibility, and fun. Putting those principles into action has created something unique--an ecosystem of real empowerment. What does that system look like? Rather than having a traditional hierarchical chain of command, AES is organized around small teams that are responsible for operations and maintenance. Moreover, AES has eliminated functional departments; there's no corporate marketing division or human resources department. For the system to work, every person must become a well-rounded generalist--a mini-CEO. That, in turn, redefines the jobs of the people at headquarters. Instead of setting strategy and making the "the big decisions," Sant and Bakke act as advisers, guardians of the principles, accountability officers, and chief encouragers. Can other companies successfully adopt the mechanics of such a system? Not unless they first adopt the shared principles that have guided AES since its inception. "Empowerment without values isn't empowerment," says Sant. "It's just technique," adds Bakke.

  1. AE sources of droplet SCC testing in type 304 stainless steel

    NASA Astrophysics Data System (ADS)

    Shiwa, Mitsuharu; Masuda, Hiroyuki; Yamawaki, Hisashi; Ito, Kaita; Enoki, Manabu

    2014-02-01

    Acoustic emission (AE) and optical video microscope (VMS) monitoring was proposed to investigate the stress corrosion cracking of type 304 stainless steels of work-hardened (WH) and solution heat treatment (ST) specimen caused by a small magnesium-chloride droplet. The crack propagation length could measure clearly under the droplet with coved glass by VMS. The cracks velocities of WH were 3.2-5.2 ×10 μm/ks and it propagated almost continuously. That of ST were 2.1-3.8 ×10 μm/ks and it propagated similar to WH. AE signals were generated at early stage of SCC testing, after that they were generated discontinuously in WH. None of AE signals were detected in ST. The detected AE signals were synchronized with bubbling from pitting and on the crack in a droplet observed by high magnification VMS. With the SEM observations, cracking bottom of pitting and small pitting on the crack were observed at the bubbling position. It could be concluded that the detected AE signals were mainly attributed to the bubbling from the pitting.

  2. Data mining based full ceramic bearing fault diagnostic system using AE sensors.

    PubMed

    He, David; Li, Ruoyu; Zhu, Junda; Zade, Mikhail

    2011-12-01

    Full ceramic bearings are considered the first step toward full ceramic, oil-free engines in the future. No research on full ceramic bearing fault diagnostics using acoustic emission (AE) sensors has been reported. Unlike their steel counterparts, signal processing methods to extract effective AE fault characteristic features and fault diagnostic systems for full ceramic bearings have not been developed. In this paper, a data mining based full ceramic bearing diagnostic system using AE based condition indicators (CIs) is presented. The system utilizes a new signal processing method based on Hilbert Huang transform to extract AE fault features for the computation of CIs. These CIs are used to build a data mining based fault classifier using a k-nearest neighbor algorithm. Seeded fault tests on full ceramic bearing outer race, inner race, balls, and cage are conducted on a bearing diagnostic test rig and AE burst data are collected. The effectiveness of the developed fault diagnostic system is validated using real full ceramic bearing seeded fault test data.

  3. Assimilation and implications of AE-9/AP-9 in the design process of JPL missions

    NASA Astrophysics Data System (ADS)

    de Soria-Santacruz Pich, M.; Jun, I.

    2015-12-01

    The NASA AE-8/AP-8 has been the standard geospace environment specification for decades. This model describes the energetic particle environment around the Earth and is currently the default model used in the design of space missions at the Jet Propulsion Laboratory (JPL). Moreover, the model plays a critical role in the determination of the shielding and survivability of the satellites orbiting our planet. A recent update supported by the Air Force Research Laboratory (AFRL) and the National Reconnaissance Office (NRO), the AE-9/AP-9 model, was released in September 2012 and included many improvements like increased spatial resolution and the specification of the uncertainty due to instrument errors or space weather variability. A current effort at JPL is in place with the objective of making a decision within the Laboratory on the transition from AE-8/AP-8 to the new AE-9/AP-9. In this study we present the results of this effort, which involves the comparison between both versions of the model for different satellite orbits, the comparison between AE-9/AP-9 and in-situ satellite data from the Van Allen Probes and the OSTM/Jason 2 satellite, and the implications of adopting the new model for spacecraft design in terms of survivability, shielding, single event effects, and spacecraft charging.

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

    SciTech Connect

    Clayton, Geoffrey C.; Sargent, B.; Boyer, M. L.; Meixner, M.; Roman-Duval, J.; Sewilo, M. E-mail: duval@stsci.ed E-mail: meixner@stsci.ed E-mail: sargent@stsci.ed

    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.

  5. 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.

  6. Synthesis, Crystal and Electronic Structures of the Pnictides AE3TrPn3 (AE = Sr, Ba; Tr = Al, Ga; Pn = P, As)

    SciTech Connect

    Stoyko, Stanislav; Voss, Leonard; He, Hua; Bobev, Svilen

    2015-09-24

    New ternary arsenides AE3TrAs3 (AE = Sr, Ba; Tr = Al, Ga) and their phosphide analogs Sr3GaP3 and Ba3AlP3 have been prepared by reactions of the respective elements at high temperatures. Single-crystal X-ray diffraction studies reveal that Sr3AlAs3 and Ba3AlAs3 adopt the Ba3AlSb3-type structure (Pearson symbol oC56, space group Cmce, Z = 8). This structure is also realized for Sr3GaP3 and Ba3AlP3. Likewise, the compounds Sr3GaAs3 and Ba3GaAs3 crystallize with the Ba3GaSb3-type structure (Pearson symbol oP56, space group Pnma, Z = 8). Both structures are made up of isolated pairs of edge-shared AlPn4 and GaPn4 tetrahedra (Pn = pnictogen, i.e., P or As), separated by the alkaline-earth Sr2+ and Ba2+ cations. In both cases, there are no homoatomic bonds, hence, regardless of the slightly different atomic arrangements, both structures can be rationalized as valence-precise [AE2+]3[Tr3+][Pn3-]3, or rather [AE2+]6[Tr2Pn6]12-, i.e., as Zintl phases.

  7. The use of MP-AES for analysis major and micronutrients in soils

    NASA Astrophysics Data System (ADS)

    Tonutare, Tonu; Rodima, Ako; Künnapas, Allan; Kõlli, Raimo; Albre, Imbi

    2016-04-01

    The ICP with OES or MS detectors is today the most common multielement technigues for soil element analysis. Although the micro-plasma has been available for decades, there were no commercially available instruments on the market. The situation changed in 2011 when the Agilent 4100 MP-AES appeared. The use of nitrogen plasma of the MP-AES provides reduction in the operational and maintenance costs compared to ICP and therefore makes it very perspective for soil analysis. The nitrogen microwave excited plasma has diferent properties compared to ICP argon plasma and this cause the specific behaviour of elements during the excitation. Here we present the results and optimal instrumental parameters for determination of soil nutrients (K, Ca, Mg, Fe and Zn) by MP-AES.

  8. HHT-based AE characteristics of natural fatigue cracks in rotating shafts

    NASA Astrophysics Data System (ADS)

    Lin, Li; Chu, Fulei

    2012-01-01

    This paper addresses an application of recently developed Hilbert-Huang transform (HHT) signal processing technique on AE feature extraction of natural fatigue cracks in rotating shafts providing an energy-frequency-time distribution with adaptable precision. A special purpose built test rig was employed for generating natural rotating fatigue crack on a shaft. Acoustic emission signals are non-stationary and nonlinear transients, whose waveforms and arrival times are unknown. A common problem in AE signal processing is to extract physical parameters of interest when these involve joint variations of time and frequency. It has been found that HHT appears to be a better tool compared to fast Fourier transform and continuous wavelet transform for natural fatigue crack characterization in a rotating rotor in all experiment cases. It was concluded that HHT-based AE technology successfully extracted the features of natural fatigue cracks induced on rotating shafts.

  9. Winter Refuge for Aedes aegypti and Ae. albopictus Mosquitoes in Hanoi during Winter

    PubMed Central

    Tsunoda, Takashi; Cuong, Tran Chi; Dong, Tran Duc; Yen, Nguyen Thi; Le, Nguyen Hoang; Phong, Tran Vu; Minakawa, Noboru

    2014-01-01

    Dengue occurs throughout the year in Hanoi, Vietnam, despite winter low temperatures <10°C. During July 2010 to March 2012, we surveyed monthly for Aedes larvae and pupae in 120 houses in 8 Hanoi districts. Aedes albopictus preferred discarded containers in summer and pupal density drastically decreased in winter. Aedes aegypti preferred concrete tanks and this preference increased in winter. Even in winter, the lowest water temperature found in concrete tanks was >14°C, exceeding the developmental zero point of Ae. aegypti. Although jars, drums and concrete tanks were the dominant containers previously (1994–97) in Hanoi, currently the percentage of residences with concrete tanks was still high while jars and drums were quite low. Our study showed that concrete tanks with broken lids allowing mosquitoes access were important winter refuge for Ae. aegypti. We also indicate a concern about concrete tanks serving as foci for Ae. aegypti to expand their distribution in cooler regions. PMID:24752230

  10. Comparative study of active and passive sensing with AE and PWAS transducers

    NASA Astrophysics Data System (ADS)

    Yu, Lingyu; Giurgiutiu, Victor; Yu, Jianguo; Ziehl, Paul; Zhao, Liuxian

    2012-04-01

    Monitoring of fatigue cracking in bridges using a combined passive and active scheme has been approached by the authors. Passive Acoustic Emission (AE) monitoring has shown to be able to detect crack growth behavior by picking up the stress waves resulting from the breathing of cracks while active ultrasonic pulsing can quantitatively assess structural integrity by sensing out an interrogating pulse and receive the structural reflections from the discontinuity. In this paper, we present a comparative study of active and passive sensing with two types of transducers: (a) AE transducers, and (b) embeddable piezoelectric wafer active sensors (PWAS). The study was performed experimentally on steel plates. Both pristine and damaged (notched) conditions were considered. For active sensing, pitchcatch configuration was examined in which one transducer was the transmitter and another transducer acted as the receiver. The ping signal was generated by the AE hardware/software package AEwin. For passive sensing, 0.5-mm lead breaks were executed both on top and on the edge of the plate. The comparative nature of the study was achieved by having the AE and PWAS transducers placed on the same location but on the opposite sides of the plate. The paper presents the main findings of this study in terms of (a) signal strength; (b) signal-to-noise (S/N) ratio; (c) waveform clarity; (d) waveform Fourier spectrum contents and bandwidth; (e) capability to detect and localize AE source; (f) capability to detect and localize damage. The paper performs a critical discussion of the two sensing methodologies, conventional AE transducers vs. PWAS transducers.

  11. Growth of Sn on Mo(110) studied by AES and STM

    NASA Astrophysics Data System (ADS)

    Krupski, A.

    2011-07-01

    Scanning tunneling microscopy (STM) and Auger electron spectroscopy (AES) have been used to investigate the growth behavior of ultra-thin Sn films on a Mo(110) surface at room temperature. An analysis of STM and AES measurements indicates that layer-by-layer growth (Frank-van der Merwe mode) for the first two layers of Sn is observed. For submonolayer coverage, tin prefers to nucleate randomly and creates one atom high islands on Mo terraces. In the completed first and second layer, no ordered regions were observed. As the sample is post-annealed to 800 K, the rearrangement of an existing film suggests a Sn-Mo surface alloy formation.

  12. Uses of AES and RGA to study neutron-irradiation-enhanced segregation to internal surfaces

    SciTech Connect

    Gessel, G.R.; White, C.L.

    1980-01-01

    The high flux of point defects to sinks during neutron irradiation can result in segregation of impurity or alloy additions to metals. Such segregants can be preexisting or produced by neutron-induced transmutations. This segregation is known to strongly influence swelling and mechanical properties. Over a period of years, facilities have been developed at ORNL incorporating AES and RGA to examine irradiated materials. Capabilities of this system include in situ tensile fracture at elevated temperatures under ultrahigh vacuum 10/sup -10/ torr and helium release monitoring. AES and normal incidence inert ion sputtering are exploited to examine segregation at the fracture surface and chemical gradients near the surface.

  13. Automated Estimating System (AES), Standard Value Update Program, user`s manual

    SciTech Connect

    Schwartz, R.K.; Holder, D.A.

    1994-08-01

    This manual contains instructions for operating the Standard Value Update Program. This program is operated and controlled by selected individuals in the Estimating and Scheduling Engineering Department of the Martin Marietta Energy Systems, Inc., Engineering Division. It is used to control and standardized input into the Automated Estimating System (AES) Estimating program, a person computer-based software package designed to aid in the creation, updating, and reporting of project cost estimates. The AES Estimating program is documented in a separate user`s manual.

  14. AES-128 Bit Algorithm Using Fully Pipelined Architecture for Secret Communication

    NASA Astrophysics Data System (ADS)

    Gnanambika, M.; Adilakshmi, S.; Noorbasha, Fazal

    2012-03-01

    In this paper, an efficient method for high speed hardware implementation of AES algorithm is presented. So far, many implementations of AES have been proposed, for various goals that effect the Sub Byte transformation in various ways. These methods of implementation are based on combinational logic and are done in polynomial bases. In the proposed architecture, it is done by using composite field arithmetic in normal bases. In addition, efficient key expansion architecture suitable for 6 sub pipelined round units is also presented. These designs were described using VerilogHDL, simulated using Modelsim.

  15. Optical Spectroscopy of X-Ray-selected Young Stars in the Carina Nebula

    NASA Astrophysics Data System (ADS)

    Vaidya, Kaushar; Chen, Wen-Ping; Lee, Hsu-Tai

    2015-12-01

    We present low-resolution optical spectra for 29 X-ray sources identified as either massive star candidates or low-mass pre-main-sequence (PMS) star candidates in the clusters Trumpler 16 and Trumpler 14 of the Carina Nebula. Spectra of two more objects (one with an X-ray counterpart, and one with no X-ray counterpart), not originally our targets, but found close (˜3″) to two of our targets, are presented as well. Twenty early-type stars, including an O8 star, seven B1-B2 stars, two B3 stars, a B5 star, and nine emission-line stars, are identified. Eleven T Tauri stars, including eight classical T Tauri stars (CTTSs) and three weak-lined T Tauri stars, are identified. The early-type stars in our sample are more reddened compared to the previously known OB stars of the region. The Chandra hardness ratios of our T Tauri stars are found to be consistent with the Chandra hardness ratios of T Tauri stars of the Orion Nebula Cluster. Most early-type stars are found to be nonvariable in X-ray emission, except the B2 star J104518.81-594217.9, the B3 star J104507.84-594134.0, and the Ae star J104424.76-594555.0, which are possible X-ray variables. J104452.20-594155.1, a CTTS, is among the brightest and the hardest X-ray sources in our sample, appears to be a variable, and shows a strong X-ray flare. The mean optical and near-infrared photometric variability in the V and Ks bands, of all sources, is found to be ˜0.04 and 0.05 mag, respectively. The T Tauri stars show significantly larger mean variation, ˜0.1 mag, in the Ks band. The addition of one O star and seven B1-B2 stars reported here contributes to an 11% increase of the known OB population in the observed field. The 11 T Tauri stars are the first ever confirmed low-mass PMS stars in the Carina Nebula region.

  16. OPTICAL SPECTROSCOPY OF X-RAY-SELECTED YOUNG STARS IN THE CARINA NEBULA

    SciTech Connect

    Vaidya, Kaushar; Chen, Wen-Ping; Lee, Hsu-Tai

    2015-12-15

    We present low-resolution optical spectra for 29 X-ray sources identified as either massive star candidates or low-mass pre-main-sequence (PMS) star candidates in the clusters Trumpler 16 and Trumpler 14 of the Carina Nebula. Spectra of two more objects (one with an X-ray counterpart, and one with no X-ray counterpart), not originally our targets, but found close (∼3″) to two of our targets, are presented as well. Twenty early-type stars, including an O8 star, seven B1–B2 stars, two B3 stars, a B5 star, and nine emission-line stars, are identified. Eleven T Tauri stars, including eight classical T Tauri stars (CTTSs) and three weak-lined T Tauri stars, are identified. The early-type stars in our sample are more reddened compared to the previously known OB stars of the region. The Chandra hardness ratios of our T Tauri stars are found to be consistent with the Chandra hardness ratios of T Tauri stars of the Orion Nebula Cluster. Most early-type stars are found to be nonvariable in X-ray emission, except the B2 star J104518.81–594217.9, the B3 star J104507.84–594134.0, and the Ae star J104424.76–594555.0, which are possible X-ray variables. J104452.20–594155.1, a CTTS, is among the brightest and the hardest X-ray sources in our sample, appears to be a variable, and shows a strong X-ray flare. The mean optical and near-infrared photometric variability in the V and K{sub s} bands, of all sources, is found to be ∼0.04 and 0.05 mag, respectively. The T Tauri stars show significantly larger mean variation, ∼0.1 mag, in the K{sub s} band. The addition of one O star and seven B1–B2 stars reported here contributes to an 11% increase of the known OB population in the observed field. The 11 T Tauri stars are the first ever confirmed low-mass PMS stars in the Carina Nebula region.

  17. Infrared emission features: probing the interstellar PAH population and circumstellar environment of Herbig Ae/Be stars

    NASA Astrophysics Data System (ADS)

    Boersma, Christiaan

    2009-12-01

    AKs zijn alom vertegenwoordigd en bieden een uitstekend middel om de veelheid aan objecten verspreid over het heelal te bestuderen. Met name in gebieden waar zich sterren en planeten vormen, helpen ze bij het ontwarren van de grootschalige structuur. PAKs staat voor polycyclische aromatische koolwaterstoffen en ze vormen een familie van grote kippengaasvormige moleculen opgebouwd uit koolstof en waterstof. Op aarde worden ze onderander aangetroffen in de verbrandingsproducten van fossiele brandstoffen. PAKs vormen het overgangsgebied van stofdeeltjes ter grote van een micron naar moleculair "gas". PAKs zijn uniek op twee manieren. Allereerst, PAKs fluoresceren na de absorptie van een enkel ultraviolet foton, waardoor ze te zien zijn in zeer koude gebieden, ver weg van de aanstralende bron. In de tweede plaats, gegeven de complexiteit van deze moleculen, kunnen ze een belangrijke rol hebben gespeeld in het ontstaan van leven. Met behulp van topklasse ruimte- en grond gestationeerde observatoria, zoals bijvoorbeeld Spitzer en de 10-meter klasse telescopen in Chili, is de PAK-emissie afkomstig van middelzware, zich vormende, sterren onderzocht. Door gebruik van zowel beeldvorming als spectroscopie, zijn morfologische en evolutionaire aspecten van de PAK-emissie vastgesteld. De NASA Ames PAK IR Spectroscopische Database is een verzameling van meer dan 600 berekend en ongeveer 200 experimenteel bepaalde spectra. Deze unieke database gaat eind 2009 publiek. Gebruikmakend van deze database is een systematische zoektocht gedaan naar kandidaten die verantwoordelijk kunnen worden gehouden voor de emissie in twee, tot op heden, niet goed bestudeerde regio's van het PAKs-spectra.

  18. ASASSN-16ae: Discovery of an Extreme (Delta V ~ 10 mag) Flare on an Ultracool Dwarf Star

    NASA Astrophysics Data System (ADS)

    Shappee, B. J.; Stanek, K. Z.; Schmidt, S.; Holoien, T. W.-S.; Brown, J. S.; Kochanek, C. S.; Godoy-Rivera, D.; Basu, U.; Prieto, J. L.; Bersier, D.; Dong, Subo; Chen, Ping; Brimacombe, J.

    2016-01-01

    During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Brutus" telescope in Haleakala, Hawaii, we discovered a new transient source: Object RA (J2000) DEC (J2000) Disc.

  19. O stars and Wolf-Rayet stars

    NASA Technical Reports Server (NTRS)

    Conti, Peter S.; Underhill, Anne B.; Jordan, Stuart (Editor); Thomas, Richard (Editor)

    1988-01-01

    Basic information is given about O and Wolf-Rayet stars indicating how these stars are defined and what their chief observable properties are. Part 2 of the volume discussed four related themes pertaining to the hottest and most luminous stars. Presented are: an observational overview of the spectroscopic classification and extrinsic properties of O and Wolf-Rayet stars; the intrinsic parameters of luminosity, effective temperature, mass, and composition of the stars, and a discussion of their viability; stellar wind properties; and the related issues concerning the efforts of stellar radiation and wind on the immediate interstellar environment are presented.

  20. Lifestyles of the Stars.

    ERIC Educational Resources Information Center

    National Aeronautics and Space Administration, Cocoa Beach, FL. John F. Kennedy Space Center.

    Some general information on stars is provided in this National Aeronautics and Space Administration pamphlet. Topic areas briefly discussed are: (1) the birth of a star; (2) main sequence stars; (3) red giants; (4) white dwarfs; (5) neutron stars; (6) supernovae; (7) pulsars; and (8) black holes. (JN)

  1. Egyptian "Star Clocks"

    NASA Astrophysics Data System (ADS)

    Symons, Sarah

    Diagonal, transit, and Ramesside star clocks are tables of astronomical information occasionally found in ancient Egyptian temples, tombs, and papyri. The tables represent the motions of selected stars (decans and hour stars) throughout the Egyptian civil year. Analysis of star clocks leads to greater understanding of ancient Egyptian constellations, ritual astronomical activities, observational practices, and pharaonic chronology.

  2. Submillimeter studies of main-sequence stars

    NASA Technical Reports Server (NTRS)

    Zuckerman, B.; Becklin, E. E.

    1993-01-01

    JCMT maps of the 800-micron emission from Vega, Fomalhaut, and Beta Pictoris are interpreted to indicate that they are not ringed by large reservoirs of distant orbiting dust particles that are too cold to have been detected by IRAS. A search for 800-micron emission from stars in the Pleiades and Ursa Majoris open clusters is reported. In comparison with the mass of dust particles near T Tauri and Herbig Ae stars, the JCMT data indicate a decline in dust mass during the initial 3 x 10 exp 8 yr that a star spends on the main sequence that is at least as rapid as (time) exp -2. It is estimated that in the Kuiper belt the ratio of total mass carried by small particles to that carried by comets is orders of magnitude smaller than this ratio is 1 AU from the sun. If 800-micron opacities calculated by Pollack et al. (1993) are correct, then the particles with radii less than 100 microns that dominate the FIR fluxes measured by IRAS cannot entirely account for the measured 800-micron fluxes at Vega, Beta Pic, and Fomalhaut; larger particles must be present as well.

  3. PMS and ZAMS stars associated with the dark cloud LDN 1655

    NASA Astrophysics Data System (ADS)

    Chavarría-K, C.; Moreno-Corral, M. A.; de Lara, E.; de la Fuente, E.

    2013-01-01

    We give results of a low-resolution optical spectroscopic study of the bright nebulous stars conforming the tight stellar trapezium embedded in IRAS06548-0815, of the exciting star of IRAS06547-0810, and of the stars associated with reflection nebulae (R-or N-stars) NJ065703.0-081421, NJ065714.1-081016, IRAS06548-0815 D and IRAS06548-0815 G, all objects scarcely observed and apparently pertaining to the dark cloud LDN 1655. Our results given here combined with the corresponding 2MASS near infrared photometry enables us to estimate a photometric distance to LDN1655 of 1.9 ± kpc and to locate the trapezium stars on the (logL∗/L⊙,logTeff) or HR diagram in an attempt to disclose about their true nature. The spectroscopy of IRAS06548-0815 revealed two classic T Tauri, two Herbig Ae/Be stars, four weak-line T Tauri stars, and two probable lithium-rich stars. Additionally, we found that the R-star IRAS06547-0810 is excited by a single B1(V) star, that IRAS06548-0815 D is excited by a SpT. B2/B3(V) star, NJ065703.0-081421 and NJ065714.1-081016 are excited by a B3/B4(V) emission star and an A6(V) star, respectively. The brightest near infrared source of the trapezium, IRS1, has an infrared luminosity comparable to a highly reddened O8(V) star (AV≈29m). The second brightest near infrared source of the trapezium, IRAS06548-0815 C is, optically, a single classical T Tauri star of spectral type K4/K5, but is a resolved binary in the 2MASSKs band, both components being of about the same brightness.

  4. A photometric catalogue of southern emission-line stars

    NASA Astrophysics Data System (ADS)

    de Winter, D.; van den Ancker, M. E.; Maira, A.; Thé, P. S.; Djie, H. R. E. Tjin A.; Redondo, I.; Eiroa, C.; Molster, F. J.

    2001-12-01

    We present a catalogue of previously unpublished optical and infrared photometry for a sample of 162 emission-line objects and shell stars visible from the southern hemisphere. The data were obtained between 1978 and 1997 in the Walraven (WULBV), Johnson/Cousins (UBV(RI)c) and ESO and SAAO near-infrared (JHKLM) photometric systems. Most of the observed objects are Herbig Ae/Be (HAeBe) stars or HAeBe candidates appearing in the list of HAeBe candidates of Thé et al. (1994), although several B[e] stars, LBVs and T Tauri stars are also included in our sample. For many of the stars the data presented here are the first photo-electric measurements in the literature. The resulting catalogue consists of 1809 photometric measurements. Optical variability was detected in 66 out of the 116 sources that were observed more than once. 15 out of the 50 stars observed multiple times in the infrared showed variability at 2.2 mu m (K band). Based on observations collected at the European Southern Observatory, La Silla, Chile and on observations collected at the South African Astronomical Observatory. Tables 2-4 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http:/ /cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/380/609

  5. Coronal evolution of solar-like stars: X-ray spectroscopy of stars in star- forming regions and the solar neighborhood

    NASA Astrophysics Data System (ADS)

    Telleschi, Alessandra Silvia

    Solar-like stars are strong X-ray emitters in both their pre-main sequence (PMS) and main-sequence (MS) phases. In analogy to the Sun, X-rays are thought to originate in a corona. However, in the case of pre-main sequence stars, accretion processes might influence the X-ray properties of the stars. In this thesis, results from X-ray spectroscopy of main-sequence solar analogs, pre-main sequence solar-like stars and a Herbig Ae/Be star are presented and discussed. All X-ray spectra have been obtained by the Reflection Grating Spectrometers (RGS) and the European Photon Imaging Cameras (EPIC) on board the XMM-Newton satellite. In the first part of the thesis, high-resolution (RGS) X-ray spectra of a sample of six main-sequence G-type stars with ages between [approximate] 0.1 Gyr and [approximate] 1.6 Gyr have been analyzed. Using individual spectral lines, the Emission Measure Distributions (EMD) and the coronal abundances have been derived. As a solar analog evolves, its rotation rate decreases and its internal magnetic dynamo weakens, resulting in a decrease of magnetic activity and a decrease of the star's X-ray luminosity. The mean coronal temperatures derived from the EMDs decrease from [approximate] 10 MK for the youngest stars to [approximate] 4 MK for the oldest star in our stellar sample. These results have been interpreted with a model in which the coronal emission is produced by a superposition of stochastically occurring flares; more active stars are found to require a larger range of flare energies than less active stars. Abundances change from an inverse First Ionization Potential (FIP) effect, where abundances with high FIP are enhanced with respect to abundances with low FIP, to a solar-like FIP effect at ages >= 0.3 Gyr. The analysis has then been extended to pre-main sequence stars in the Taurus- Auriga complex. The results presented here are part of a large survey, the "XMM-Newton Extended Survey of the Taurus Molecular Cloud" (XEST). High- and

  6. Unseen but present danger: improving the safe prescribing of anti-embolism stockings (AES).

    PubMed

    Bradley, Alison

    2014-01-01

    A strong evidence base exists supporting thromboprophylaxis for venous thromboembolism (VTE) in surgical patients. Given the ageing population, obesity epidemic, and rise in type 2 diabetes, VTE and peripheral vascular disease (PAD) are likely to become an escalating problem. PAD is a contraindication to the use of anti-embolism stockings (AES). Half of those patients diagnosed with PAD report no symptoms, potentially underestimating its prevalence. Implementation of guidelines for thromboprophylaxis, including the safe prescribing of AES, is therefore imperative. The aims of this project were to establish whether thromboprophylaxis was being prescribed correctly, and appropriately, to all surgical inpatients. This included documented evidence that peripheral pulses had been examined - and, in the case of diabetic patients, that there was documentation of full peripheral neurovascular examination - before AES were prescribed. Data were collected from case notes of all surgical inpatients. Foundation year 1 doctors (FY1s) completed a questionnaire assessing their knowledge of local guidelines. Teaching sessions and posters summarising local guidelines were delivered to FY1s. Appropriate pharmacological prescribing improved from 57.69% to 100%. AES were appropriately prescribed for 65.38% of patients. Post intervention this increased to 79.17%. 0% had documented peripheral neurovascular examination. This increased to 50% post intervention.

  7. The Impact of Church Affiliation on Language Use in Kwara'ae (Solomon Islands).

    ERIC Educational Resources Information Center

    Watson-Gegeo, Karen Ann; Gegeo, David Welchman

    1991-01-01

    The impact of church affiliation on language use, identity, and change among Kwara'ae speakers in the Solomon Islands is examined. It was found that members of different sects signal their separate identities not only through linguistic code but also through discourse patterns and nonverbal aspects of communication. (26 references) (JL)

  8. Production and Perception of the English /ae/-/?/ Contrast in Switched-Dominance Speakers

    ERIC Educational Resources Information Center

    Casillas, Joseph V.; Simonet, Miquel

    2016-01-01

    This study investigates how fluent second-language (L2) learners of English produce and perceive the /ae/-/?/ vowel contrast of Southwestern American English. Two learner groups are examined: (1) early, proficient English speakers who were raised by Spanish-speaking families but who became dominant in English during childhood and, as adults, lack…

  9. 75 FR 57660 - Airworthiness Directives; Rolls-Royce Corporation (RRC) AE 3007A Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-22

    ... Corporation (RRC) AE 3007A Series Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... series turbofan engines. That AD currently requires performing an eddy current inspection (ECI) or...-08-51, Amendment 39-15905 (74 FR 22091, May 12, 2009), with a proposed AD. The proposed AD applies...

  10. Public Health Response to Aedes aegypti and Ae. albopictus Mosquitoes Invading California, USA.

    PubMed

    Porse, Charsey Cole; Kramer, Vicki; Yoshimizu, Melissa Hardstone; Metzger, Marco; Hu, Renjie; Padgett, Kerry; Vugia, Duc J

    2015-10-01

    Aedes aegypti and Ae. albopictus mosquitoes, primary vectors of dengue and chikungunya viruses, were recently detected in California, USA. The threat of potential local transmission of these viruses increases as more infected travelers arrive from affected areas. Public health response has included enhanced human and mosquito surveillance, education, and intensive mosquito control.

  11. 76 FR 4089 - Proposed Information Collection; Comment Request; Automated Export System (AES) Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-24

    ... publish export trade data. Title 15, Code of Federal Regulations (CFR), Part 30, contains the regulatory... policies that affect the economy. These data also enable U.S. businesses to develop practical export... economy. These data collected from the AES record are also used for export control purposes under Title...

  12. Program of Aes Orbit Determination from Measurement Data of Astronomical Station ("orbita - M")

    NASA Astrophysics Data System (ADS)

    Sheptoon, A. D.; Kolesnik, S. Ja.; Paltsev, N. G.

    A program is developed of determining AES orbits from measurement data of one or several astronomical stations. Its algorithm is rather stable to small errors of measurements and permits to use data with low accuracy for calculations.The use of several transits data enables to increase presision of orbital semi-major axe determination by nearly 10000 times.

  13. Investigation of Participation in Adult Education in Turkey: AES Data Analysis

    ERIC Educational Resources Information Center

    Dincer, N. Nergiz; Tekin-Koru, Ayca; Askar, Petek

    2016-01-01

    The aim of this study is to identify the determinants of participation in adult education in Turkey. The analysis is conducted using the Adult Education Survey (AES), conducted by TurkStat. The results indicate that economic growth in the sector of employment significantly and positively affects the odds for adult education participation. The data…

  14. An intramolecular transport metabolon: fusion of carbonic anhydrase II to the COOH terminus of the Cl(-)/HCO(3)(-)exchanger, AE1.

    PubMed

    Sowah, Daniel; Casey, Joseph R

    2011-08-01

    Anion exchanger 1 (AE1) is the plasma membrane Cl(-)/HCO(3)(-) exchanger of erythrocytes. Carbonic anhydrases (CA) provide substrate for AE1 by catalyzing the reaction, H(2)O + CO(2) ↔ HCO(3)(-) + H(+). The physical complex of CAII with AE1 has been proposed to maximize anion exchange activity. To examine the effect of CAII catalysis on AE1 transport rate, we fused either CAII-wild type or catalytically inactive CAII-V143Y to the cytoplasmic COOH terminus of AE1 to form AE1.CAII and AE1.CAII-V143Y, respectively. When expressed in transfected human embryonic kidney 293 cells, AE1.CAII had a similar Cl(-)/HCO(3)(-) exchange activity to AE1 alone, as assessed by the flux of H(+) equivalents (87 ± 4% vs. AE1) or rate of change of intracellular Cl(-) concentration (93 ± 4% vs. AE1), suggesting that CAII does not activate AE1. In contrast, AE1.CAII-V143Y displayed transport rates for H(+) equivalents and Cl(-) of 55 ± 2% and of 40 ± 2%, versus AE1. Fusion of CAII to AE1 therefore reduces anion transport activity, but this reduction is compensated for during Cl(-)/HCO(3)(-) exchange by the presence of catalytically active CAII. Overexpression of free CAII-V143Y acts in a dominant negative manner to reduce AE1-mediated HCO(3)(-) transport by displacement of endogenous CAII-wild type from its binding site on AE1. To examine whether AE1.CAII bound endogenous CAII, we coexpressed CAII-V143Y along with AE1 or AE1.CAII. The bicarbonate transport activity of AE1 was inhibited by CAII-V143Y, whereas the activity of AE1.CAII was unaffected by CAII-V143Y, suggesting impaired transport activity upon displacement of functional CAII from AE1 but not AE1.CAII. Taken together, these data suggest that association of functional CAII with AE1 increases Cl(-)/HCO(3)(-) exchange activity, consistent with the HCO(3)(-) transport metabolon model.

  15. Neutron Stars and NuSTAR

    NASA Astrophysics Data System (ADS)

    Bhalerao, Varun

    2012-05-01

    My thesis centers around the study of neutron stars, especially those in massive binary systems. To this end, it has two distinct components: the observational study of neutron stars in massive binaries with a goal of measuring neutron star masses and participation in NuSTAR, the first imaging hard X-ray mission, one that is extremely well suited to the study of massive binaries and compact objects in our Galaxy. The Nuclear Spectroscopic Telescope Array (NuSTAR) is a NASA Small Explorer mission that will carry the first focusing high energy X-ray telescope to orbit. NuSTAR has an order-of-magnitude better angular resolution and has two orders of magnitude higher sensitivity than any currently orbiting hard X-ray telescope. I worked to develop, calibrate, and test CdZnTe detectors for NuSTAR. I describe the CdZnTe detectors in comprehensive detail here - from readout procedures to data analysis. Detailed calibration of detectors is necessary for analyzing astrophysical source data obtained by the NuSTAR. I discuss the design and implementation of an automated setup for calibrating flight detectors, followed by calibration procedures and results. Neutron stars are an excellent probe of fundamental physics. The maximum mass of a neutron star can put stringent constraints on the equation of state of matter at extreme pressures and densities. From an astrophysical perspective, there are several open questions in our understanding of neutron stars. What are the birth masses of neutron stars? How do they change in binary evolution? Are there multiple mechanisms for the formation of neutron stars? Measuring masses of neutron stars helps answer these questions. Neutron stars in high-mass X-ray binaries have masses close to their birth mass, providing an opportunity to disentangle the role of "nature" and "nurture" in the observed mass distributions. In 2006, masses had been measured for only six such objects, but this small sample showed the greatest diversity in masses

  16. Organizing for empowerment: an interview with AES's Roger Sant and Dennis Bakke. Interview by Suzy Wetlaufer.

    PubMed

    Sant, R; Bakke, D

    1999-01-01

    The topic of empowerment is receiving a lot of attention, but how many employees are truly empowered? At the global electricity giant AES Corporation, the answer is all 40,000 of them. In this interview, chairman Roger Sant and CEO Dennis Bakke reflect on their trials and triumphs in creating an exceptional company and explain how their employee-run company works. When they founded AES in 1981, Sant and Bakke set out to create a company where people could have engaging experiences on a daily basis--a company that embodied the principles of fairness, integrity, social responsibility, and fun. Putting those principles into action has created something unique--an ecosystem of real empowerment. What does that system look like? Rather than having a traditional hierarchical chain of command, AES is organized around small teams that are responsible for operations and maintenance. Moreover, AES has eliminated functional departments; there's no corporate marketing division or human resources department. For the system to work, every person must become a well-rounded generalist--a mini-CEO. That, in turn, redefines the jobs of the people at headquarters. Instead of setting strategy and making the "the big decisions," Sant and Bakke act as advisers, guardians of the principles, accountability officers, and chief encouragers. Can other companies successfully adopt the mechanics of such a system? Not unless they first adopt the shared principles that have guided AES since its inception. "Empowerment without values isn't empowerment," says Sant. "It's just technique," adds Bakke. PMID:10345387

  17. Acoustic emission (AE) health monitoring of diaphragm type couplings using neural network analysis

    NASA Astrophysics Data System (ADS)

    Godinez-Azcuaga, Valery F.; Shu, Fong; Finlayson, Richard D.; O'Donnell, Bruce

    2005-05-01

    This paper presents the latest results obtained from Acoustic Emission (AE) monitoring and detection of cracks and/or damage in diaphragm couplings, which are used in some aircraft and engine drive systems. Early detection of mechanical failure in aircraft drive train components is a key safety and economical issue with both military and civil sectors of aviation. One of these components is the diaphragm-type coupling, which has been evaluated as the ideal drive coupling for many application requirements such as high speed, high torque, and non-lubrication. Its flexible axial and angular displacement capabilities have made it indispensable for aircraft drive systems. However, diaphragm-type couplings may develop cracks during their operation. The ability to monitor, detect, identify, and isolate coupling cracks on an operational aircraft system is required in order to provide sufficient advance warning to preclude catastrophic failure. It is known that metallic structures generate characteristic Acoustic Emission (AE) during crack growth/propagation cycles. This phenomenon makes AE very attractive among various monitoring techniques for fault detection in diaphragm-type couplings. However, commercially available systems capable of automatic discrimination between signals from crack growth and normal mechanical noise are not readily available. Positive classification of signals requires experienced personnel and post-test data analysis, which tend to be a time-consuming, laborious, and expensive process. With further development of automated classifiers, AE can become a fully autonomous fault detection technique requiring no human intervention after implementation. AE has the potential to be fully integrated with automated query and response mechanisms for system/process monitoring and control.

  18. The Cambridge Double Star Atlas

    NASA Astrophysics Data System (ADS)

    MacEvoy, Bruce; Tirion, Wil

    2015-12-01

    Preface; What are double stars?; The binary orbit; Double star dynamics; Stellar mass and the binary life cycle; The double star population; Detecting double stars; Double star catalogs; Telescope optics; Preparing to observe; Helpful accessories; Viewing challenges; Next steps; Appendices: target list; Useful formulas; Double star orbits; Double star catalogs; The Greek alphabet.

  19. Anisotropic electrical and thermal conductivity in Bi2AE2Co2O8+δ [AE = Ca, Sr1-xBax (x = 0.0, 0.25, 0.5, 0.75, 1.0)] single crystals

    NASA Astrophysics Data System (ADS)

    Dong, Song-Tao; Zhang, Bin-Bin; Xiong, Ye; Lv, Yang-Yang; Yao, Shu-Hua; Chen, Y. B.; Zhou, Jian; Zhang, Shan-Tao; Chen, Yan-Feng

    2015-09-01

    Bi2AE2Co2O8+δ (AE represents alkaline earth), constructed by stacking of rock-salt Bi2AE2O4 and triangle CoO2 layers alternatively along c-axis, is one of promising thermoelectric oxides. The most impressive feature of Bi2AE2Co2O8+δ, as reported previously, is their electrical conductivity mainly lying along CoO2 plane, adjusting Bi2AE2O4 layer simultaneously manipulates both thermal conductivity and electrical conductivity. It in turn optimizes thermoelectric performance of these materials. In this work, we characterize the anisotropic thermal and electrical conductivity along both ab-plane and c-direction of Bi2AE2Co2O8+δ (AE = Ca, Sr, Ba, Sr1-xBax) single crystals. The results substantiate that isovalence replacement in Bi2AE2Co2O8+δ remarkably modifies their electrical property along ab-plane; while their thermal conductivity along ab-plane only has a slightly difference. At the same time, both the electrical conductivity and thermal conductivity along c-axis of these materials also have dramatic changes. Certainly, the electrical resistance along c-axis is too high to be used as thermoelectric applications. These results suggest that adjusting nano-block Bi2AE2O4 layer in Bi2AE2Co2O8+δ cannot modify the thermal conductivity along high electrical conductivity plane (ab-plane here). The evolution of electrical property is discussed by Anderson localization and electron-electron interaction U. And the modification of thermal conductivity along c-axis is attributed to the microstructure difference. This work sheds more light on the manipulation of the thermal and electrical conductivity in the layered thermoelectric materials.

  20. Characterization of Maize Amylose-Extender (ae) Mutant Starches. Part I: Relationship Between Resistant Starch Contents and Molecular Structures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Endosperm starches were isolated from kernels of seven maize amylose-extender (ae) lines. The resistant starch (RS) contents, measured using AOAC method 991.43, showed that three new ae-mutant starch lines developed by the USDA-ARS Germplasm Enhancement (GEM) and Truman State University had larger R...

  1. 40 CFR 174.530 - Bacillus thuringiensis Cry2Ae protein in cotton; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... in cotton; exemption from the requirement of a tolerance. 174.530 Section 174.530 Protection of... Cry2Ae protein in cotton; exemption from the requirement of a tolerance. Residues of Bacillus thuringiensis Cry2Ae protein in or on the food and feed commodities of cotton; cotton, undelinted seed;...

  2. 40 CFR 174.530 - Bacillus thuringiensis Cry2Ae protein in cotton; temporary exemption from the requirement of a...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... in cotton; temporary exemption from the requirement of a tolerance. 174.530 Section 174.530... thuringiensis Cry2Ae protein in cotton; temporary exemption from the requirement of a tolerance. Residues of Bacillus thuringiensis Cry2Ae protein in or on the food commodities of cotton, cotton; cotton,...

  3. 40 CFR 174.530 - Bacillus thuringiensis Cry2Ae protein in cotton; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... in cotton; exemption from the requirement of a tolerance. 174.530 Section 174.530 Protection of... Cry2Ae protein in cotton; exemption from the requirement of a tolerance. Residues of Bacillus thuringiensis Cry2Ae protein in or on the food and feed commodities of cotton; cotton, undelinted seed;...

  4. 40 CFR 174.530 - Bacillus thuringiensis Cry2Ae protein in cotton; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... in cotton; exemption from the requirement of a tolerance. 174.530 Section 174.530 Protection of... Cry2Ae protein in cotton; exemption from the requirement of a tolerance. Residues of Bacillus thuringiensis Cry2Ae protein in or on the food and feed commodities of cotton; cotton, undelinted seed;...

  5. 40 CFR 174.530 - Bacillus thuringiensis Cry2Ae protein in cotton; temporary exemption from the requirement of a...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... in cotton; temporary exemption from the requirement of a tolerance. 174.530 Section 174.530... thuringiensis Cry2Ae protein in cotton; temporary exemption from the requirement of a tolerance. Residues of Bacillus thuringiensis Cry2Ae protein in or on the food commodities of cotton, cotton; cotton,...

  6. 19 CFR 192.13 - Revocation of participants' AES post-departure (Option 4) filing privileges; appeal procedures.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Revocation of participants' AES post-departure... participants' AES post-departure (Option 4) filing privileges; appeal procedures. (a) Reasons for revocation... days of receipt of the notice of decision. Except as stated elsewhere in this paragraph, the...

  7. 75 FR 70742 - AES Laurel Mountain, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-18

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission AES Laurel Mountain, LLC; Supplemental Notice That Initial Market-Based Rate... notice in the above-referenced proceeding of AES Laurel Mountain, LLC's application for market-based...

  8. Production of Mucosally Transmissible SHIV Challenge Stocks from HIV-1 Circulating Recombinant Form 01_AE env Sequences

    PubMed Central

    Tartaglia, Lawrence J.; Chang, Hui-Wen; Lee, Benjamin C.; Abbink, Peter; Ng’ang’a, David; Boyd, Michael; Lavine, Christy L.; Lim, So-Yon; Sanisetty, Srisowmya; Whitney, James B.; Seaman, Michael S.; Rolland, Morgane; Tovanabutra, Sodsai; Ananworanich, Jintanat; Robb, Merlin L.; Kim, Jerome H.; Michael, Nelson L.; Barouch, Dan H.

    2016-01-01

    Simian-human immunodeficiency virus (SHIV) challenge stocks are critical for preclinical testing of vaccines, antibodies, and other interventions aimed to prevent HIV-1. A major unmet need for the field has been the lack of a SHIV challenge stock expressing circulating recombinant form 01_AE (CRF01_AE) env sequences. We therefore sought to develop mucosally transmissible SHIV challenge stocks containing HIV-1 CRF01_AE env derived from acutely HIV-1 infected individuals from Thailand. SHIV-AE6, SHIV-AE6RM, and SHIV-AE16 contained env sequences that were >99% identical to the original HIV-1 isolate and did not require in vivo passaging. These viruses exhibited CCR5 tropism and displayed a tier 2 neutralization phenotype. These challenge stocks efficiently infected rhesus monkeys by the intrarectal route, replicated to high levels during acute infection, and established chronic viremia in a subset of animals. SHIV-AE16 was titrated for use in single, high dose as well as repetitive, low dose intrarectal challenge studies. These SHIV challenge stocks should facilitate the preclinical evaluation of vaccines, monoclonal antibodies, and other interventions targeted at preventing HIV-1 CRF01_AE infection. PMID:26849216

  9. [Software development of multi-element transient signal acquisition and processing with multi-channel ICP-AES].

    PubMed

    Zhang, Y; Zhuang, Z; Wang, X; Zhu, E; Liu, J

    2000-02-01

    A software for multi-channel ICP-AES multi-element transient signal acquisition and processing were developed in this paper. It has been successfully applied to signal acquisition and processing in many transient introduction techniques on-line hyphenated with multi-channel ICP-AES.

  10. Characterization of Novel HIV-1 Intersubtype CRF01_AE/C and A1/C Recombinants from India

    PubMed Central

    Pandey, Sudhanshu Shekhar; Thakar, Madhuri

    2015-01-01

    We report here three novel HIV-1 intersubtype recombinants from India. One among those is a recombinant between subtype C and CRF01_AE and another two between A1 and C. A recombinant virus with CRF01_AE is reported for the first time from India. PMID:26294622

  11. AE index forecast at different time scales through an ANN algorithm based on L1 IMF and plasma measurements

    NASA Astrophysics Data System (ADS)

    Pallocchia, G.; Amata, E.; Consolini, G.; Marcucci, M. F.; Bertello, I.

    2008-02-01

    The AE index is known to have two main components, one directly driven by the solar wind and the other related to the magnetotail unloading process. As regards the role played by the IMF and solar wind parameters, recently several authors used artificial neural networks (ANN) to forecast AE from solar wind data. Following this track, in this paper we present a study of the AE forecast at different time scales, from 5 min to 1 h, in order to check whether the performance of the ANN prediction varies significantly as a function of the AE time resolution.The study is based on a new ANN Elman network with Bz (in GSM) and Vx as inputs, one hidden layer containing four neurons, four context units and one output neuron. We find that the forecast AE values, during disturbed AE periods, result to be always smaller than the experimental values; on the other hand, the algorithm performance improves as the time scale increases, i.e. the total standard deviation (calculated over a test data set) between the forecast and the Kyoto AE decreases as the averaging time increases. Under the hypothesis that this decrease follows an exponential law, we find that the 1 h scale normalised standard deviation is 0.975, very close to the asymptotic value of 0.95 for an infinite averaging time. We interpret our results in the sense that the unloading component of the AE variations cannot be predicted from IMF and solar wind parameters only.

  12. 75 FR 8326 - AES ES Westover, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-24

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission AES ES Westover, LLC; Supplemental Notice That Initial Market- Based Rate... notice in the above-referenced proceeding of AES ES Westover, LLC's application for market-based...

  13. 42 CFR 84.153 - Airflow resistance test, Type A and Type AE supplied-air respirators; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Airflow resistance test, Type A and Type AE supplied-air respirators; minimum requirements. 84.153 Section 84.153 Public Health PUBLIC HEALTH SERVICE... A and Type AE supplied-air respirators; minimum requirements. (a) Airflow resistance will...

  14. 42 CFR 84.153 - Airflow resistance test, Type A and Type AE supplied-air respirators; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Airflow resistance test, Type A and Type AE supplied-air respirators; minimum requirements. 84.153 Section 84.153 Public Health PUBLIC HEALTH SERVICE... A and Type AE supplied-air respirators; minimum requirements. (a) Airflow resistance will...

  15. 76 FR 39868 - AES Thames, L.L.C.; Supplemental Notice That Initial Market-Based Rate Filing Includes Request...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-07

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission AES Thames, L.L.C.; Supplemental Notice That Initial Market-Based Rate...-referenced proceeding of AES Thames, LLC's application for market-based rate authority, with an...

  16. 19 CFR 192.12 - Criteria for denial of applications requesting AES post-departure (Option 4) filing status...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Regulations (15 CFR 30.7(d)); (2) The applicant has a history of non-compliance with export regulations (e.g... 19 Customs Duties 2 2010-04-01 2010-04-01 false Criteria for denial of applications requesting AES...) EXPORT CONTROL Filing of Export Information Through the Automated Export System (AES) § 192.12...

  17. 77 FR 71189 - AES Beaver Valley, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-29

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission AES Beaver Valley, LLC; Supplemental Notice That Initial Market- Based Rate...-referenced proceeding, of AES Beaver Valley, LLC's application for market-based rate authority, with...

  18. Boson stars: Gravitational equilibria of self-interacting scalar fields

    SciTech Connect

    Colpi, M.; Shapiro, S.L.; Wasserman, I.

    1986-11-17

    Spherically symmetric gravitational equilibria of self-interacting scalar fields phi with interaction potential V(phi) = (1/4)lambdachemically bondphichemically bond/sup 4/ are determined. Surprisingly, the resulting configurations may differ markedly from the noninteracting case even when lambda<<1. Contrary to generally accepted astrophysical folklore, it is found that the maximum masses of such boson stars may be comparable to the Chandrasekhar mass for fermions of mass m/sub fermion/--lambda/sup -1/4/m/sub boson/. .AE

  19. The predominant cluster of CRF01_AE circulating among newly diagnosed HIV-1-positive people in Anhui Province, China.

    PubMed

    Wu, Jianjun; Shen, Yuelan; Zhong, Ping; Feng, Yi; Xing, Hui; Jin, Lin; Qin, Yizu; Liu, Aiwen; Miao, Lifeng; Cui, Lili; Su, Bin; Guo, Hongxiong

    2015-09-01

    CRF01_AE, which has led a new epidemic in many provinces in China and has displayed complex characteristics, has now evolved into multiple clusters in China. Some clusters often circulate in specific regions or among specific risk populations in China. To better determine the characteristics of CRF01_AE circulating in Anhui Province, we analyzed CRF01_AE based on gag and pol sequences. Our results showed that CRF01_AE circulating in Anhui Province was clearly divided into three clusters. Cluster 1 covered 90% of the sequences in all CRF01_AE. Among Cluster 1, the sequences from men who have sex with men (MSM) and heterosexuals were interwoven. It is suggested that MSM may play a bridge role in transmitting HIV-1 among the different risk groups.

  20. Realization and optimization of AES algorithm on the TMS320DM6446 based on DaVinci technology

    NASA Astrophysics Data System (ADS)

    Jia, Wen-bin; Xiao, Fu-hai

    2013-03-01

    The application of AES algorithm in the digital cinema system avoids video data to be illegal theft or malicious tampering, and solves its security problems. At the same time, in order to meet the requirements of the real-time, scene and transparent encryption of high-speed data streams of audio and video in the information security field, through the in-depth analysis of AES algorithm principle, based on the hardware platform of TMS320DM6446, with the software framework structure of DaVinci, this paper proposes the specific realization methods of AES algorithm in digital video system and its optimization solutions. The test results show digital movies encrypted by AES128 can not play normally, which ensures the security of digital movies. Through the comparison of the performance of AES128 algorithm before optimization and after, the correctness and validity of improved algorithm is verified.

  1. Photoevaporating Disks around Young Stars: Ultracompact HII Regions and Protoplanetary Disks.

    NASA Astrophysics Data System (ADS)

    Johnstone, Douglas Ian

    1995-01-01

    Newly formed stars produce sufficient Lyman continuum luminosity phi to significantly alter the structure and evolution of the accretion disk surrounding them. In the absence of a stellar wind, a nearly static, photoionized, 10^4 K, disk atmosphere, with a scale height that increases with disk radius varpi as varpi^{3/2 }, forms inside the gravitational radius varpig ~ 1014(M_*/ M_odot) cm where M _* is the mass of the central star. This ionized atmosphere is maintained by both the direct radiation from the central star and the diffuse field produced in the disk atmosphere by the significant fraction of hydrogen recombinations directly to the ground state. Beyond varpig the material evaporated from the disk is capable of escaping from the system and produces an ionized disk wind. The mass-loss due to this disk wind peaks at varpig . The inclusion of a stellar wind into the basic picture reduces the height of the inner disk atmosphere and introduces a new scale radius varpi_ {w} where the thermal pressure of the material evaporated from the disk balances the ram pressure in the wind. In this case the mass-loss due to the disk wind peaks at varpiw and is enhanced over the no-wind case. The photoevaporation of disks around newly formed stars has significance to both ultracompact HII regions and the dispersal of solar-type nebulae. High mass stars are intrinsically hot and thus yield sufficient Lyman luminosity to create, even without a stellar wind, disk mass-loss rates of order 2 times 10 ^{-5}phi_sp{49} {1/2} M_odotyr ^{-1}, where phi 49 = phi/(10 49 Lyman continuum photons s^{-1}). This wind, which will last until the disk is dispersed, ~ 10^5 yrs if the disk mass is M_ {d}~0.3M_*, yields sizes, emission measures and ages consistent with observations of ultracompact HII regions. The well-observed high mass star MWC 349 may be the best example to date of an evaporating disk around a high mass star. On the other end of the stellar scale, many newly formed low

  2. Loss of the AE3 Anion Exchanger in a Hypertrophic Cardiomyopathy Model Causes Rapid Decompensation and Heart Failure

    PubMed Central

    Al Moamen, Nabeel J.; Prasad, Vikram; Bodi, Ilona; Miller, Marian L.; Neiman, Michelle L.; Lasko, Valerie M.; Alper, Seth L.; Wieczorek, David F.; Lorenz, John N.; Shull, Gary E.

    2010-01-01

    The AE3 Cl−/HCO3− exchanger is abundantly expressed in the sarcolemma of cardiomyocytes, where it mediates Cl−-uptake and HCO3−-extrusion. Inhibition of AE3-mediated Cl−/HCO3− exchange has been suggested to protect against cardiac hypertrophy; however, other studies indicate that AE3 might be necessary for optimal cardiac function. To test these hypotheses we crossed AE3-null mice, which appear phenotypically normal, with a hypertrophic cardiomyopathy mouse model carrying a Glu180Gly mutation in α–tropomyosin (TM180). Loss of AE3 had no effect on hypertrophy; however, survival of TM180/AE3 double mutants was sharply reduced compared with TM180 single mutants. Analysis of cardiac performance revealed impaired cardiac function in TM180 and TM180/AE3 mutants. TM180/AE3 double mutants were more severely affected and exhibited little response to β-adrenergic stimulation, a likely consequence of their more rapid progression to heart failure. Increased expression of calmodulin-dependent kinase II and protein phosphatase 1 and differences in methylation and localization of protein phosphatase 2A were observed, but were similar in single and double mutants. Phosphorylation of phospholamban on Ser16 was sharply increased in both single and double mutants relative to wild-type hearts under basal conditions, leading to reduced reserve capacity for β-adrenergic stimulation of phospholamban phosphorylation. Imaging analysis of isolated myocytes revealed reductions in amplitude and decay of Ca2+ transients in both mutants, with greater reductions in TM180/AE3 mutants, consistent with the greater severity of their heart failure phenotype. Thus, in the TM180 cardiomyopathy model, loss of AE3 had no apparent anti-hypertrophic effect and led to more rapid decompensation and heart failure. PMID:21056571

  3. The Millennium Star Atlas

    NASA Astrophysics Data System (ADS)

    Sinnott, R. W.

    1997-08-01

    Derived from Hipparcos and Tycho observations, the Millennium Star Atlas is a set of 1548 charts covering the entire sky to about magnitude 11. It stands apart from all previous printed atlases in completeness to magnitude 10 and in uniformity around the sky. The generous chart scale has made possible a number of innovations never before seen in a star atlas: arrows on high-proper-motion stars, double-star ticks conveying separation and position angle for a specific modern epoch, distance labels for nearby stars, and variable stars coded by amplitude, period, and type. Among the nonstellar objects plotted, more than 8000 galaxies are shown with aspect ratio and orientation.

  4. The Pistol Star

    NASA Astrophysics Data System (ADS)

    Najarro, F.; Figer, D. F.

    1998-06-01

    Results of an spectroscopic investigation of the Pistol star are presented. The near-infrared spectra and photometry data are fit with stellar wind models to find that the star is extraordinarily luminous, L = 106.7±0.5 L⊙, making it one of the most luminous stars known. Coupled with the relatively cool temperature, Teff = 10^{4.17_{ - 0.06}^{ + 0.19} } K, the star is clearly in violation of the Humphreys-Davidson limit. The derived line of sight velocity of the star assures its membership in the Quintuplet cluster. This, along with the inferred extinction, places the star at the Galactic Center.

  5. 3AE8: monoclonal antibody defining inflammatory macrophages in three species.

    PubMed

    Chen, Z; Yen, S E; Walker, W S

    1984-01-01

    A mouse monoclonal antibody (MAb 3AE8) of the IgG1 isotype was prepared against rabbit splenocytes and was found by indirect immunofluorescence and direct binding assays to react, in the rabbit, primarily with oil-induced peritoneal exudate macrophages (PEM phi). This MAb did not bind to rabbit T cells, B cells, polymorphonuclear leukocytes, or resident alveolar or peritoneal M phi but it did bind to a subpopulation of rabbit splenocytes with surface characteristics of null cells. The antibody also recognized mouse and rat PEM phi as well as the murine M phi cell lines P388D1 and IC-21. Consistent with findings in the rabbit, it did not bind to M phi obtained from the peritoneal cavities of rats or mice. The addition of MAb 3AE8 to mouse PEM phi caused a marked enhancement in the phagocytic uptake of erythrocyte target cells sensitized with a mouse antierythrocyte antiserum. PMID:6480022

  6. Modified Redundancy based Technique—a New Approach to Combat Error Propagation Effect of AES

    NASA Astrophysics Data System (ADS)

    Sarkar, B.; Bhunia, C. T.; Maulik, U.

    2012-06-01

    Advanced encryption standard (AES) is a great research challenge. It has been developed to replace the data encryption standard (DES). AES suffers from a major limitation of error propagation effect. To tackle this limitation, two methods are available. One is redundancy based technique and the other one is bite based parity technique. The first one has a significant advantage of correcting any error on definite term over the second one but at the cost of higher level of overhead and hence lowering the processing speed. In this paper, a new approach based on the redundancy based technique is proposed that would certainly speed up the process of reliable encryption and hence the secured communication.

  7. A SOPC-BASED Evaluation of AES for 2.4 GHz Wireless Network

    NASA Astrophysics Data System (ADS)

    Ken, Cai; Xiaoying, Liang

    In modern systems, data security is needed more than ever before and many cryptographic algorithms are utilized for security services. Wireless Sensor Networks (WSN) is an example of such technologies. In this paper an innovative SOPC-based approach for the security services evaluation in WSN is proposed that addresses the issues of scalability, flexible performance, and silicon efficiency for the hardware acceleration of encryption system. The design includes a Nios II processor together with custom designed modules for the Advanced Encryption Standard (AES) which has become the default choice for various security services in numerous applications. The objective of this mechanism is to present an efficient hardware realization of AES using very high speed integrated circuit hardware description language (Verilog HDL) and expand the usability for various applications. As compared to traditional customize processor design, the mechanism provides a very broad range of cost/performance points.

  8. BOREAS AES Five-Day Averaged Surface Meteorological and Upper Air Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Strub, Richard; Newcomer, Jeffrey A.

    2000-01-01

    The Canadian Atmospheric Environment Service (AES) provided BOREAS with hourly and daily surface meteorological data from 23 of the AES meteorological stations located across Canada and upper air data from 1 station at The Pas, Manitoba. Due to copyright restrictions on the full resolution surface meteorological data, this data set contains 5-day average values for the surface parameters. The upper air data are provided in their full resolution form. The 5-day averaging was performed in order to create a data set that could be publicly distributed at no cost. Temporally, the surface meteorological data cover the period of January 1975 to December 1996 and the upper air data cover the period of January 1961 to November 1996. The data are provided in tabular ASCII files, and are classified as AFM-staff data. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  9. [Application of kalman filtering based on wavelet transform in ICP-AES].

    PubMed

    Qin, Xia; Shen, Lan-sun

    2002-12-01

    Kalman filtering is a recursive algorithm, which has been proposed as an attractive alternative to correct overlapping interferences in ICP-AES. However, the noise in ICP-AES contaminates the signal arising from the analyte and hence limits the accuracy of kalman filtering. Wavelet transform is a powerful technique in signal denoising due to its multi-resolution characteristics. In this paper, first, the effect of noise on kalman filtering is discussed. Then we apply the wavelet-transform-based soft-thresholding as the pre-processing of kalman filtering. The simulation results show that the kalman filtering based on wavelet transform can effectively reduce the noise and increase the accuracy of the analysis. PMID:12914186

  10. Intrinsically variable stars

    NASA Technical Reports Server (NTRS)

    Bohm-Vitense, Erika; Querci, Monique

    1987-01-01

    The characteristics of intrinsically variable stars are examined, reviewing the results of observations obtained with the IUE satellite since its launch in 1978. Selected data on both medium-spectral-class pulsating stars (Delta Cep stars, W Vir stars, and related groups) and late-type variables (M, S, and C giants and supergiants) are presented in spectra, graphs, and tables and described in detail. Topics addressed include the calibration of the the period-luminosity relation, Cepheid distance determination, checking stellar evolution theory by the giant companions of Cepheids, Cepheid masses, the importance of the hydrogen convection zone in Cepheids, temperature and abundance estimates for Population II pulsating stars, mass loss in Population II Cepheids, SWP and LWP images of cold giants and supergiants, temporal variations in the UV lines of cold stars, C-rich cold stars, and cold stars with highly ionized emission lines.

  11. Star Formation in Galaxies

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Topics addressed include: star formation; galactic infrared emission; molecular clouds; OB star luminosity; dust grains; IRAS observations; galactic disks; stellar formation in Magellanic clouds; irregular galaxies; spiral galaxies; starbursts; morphology of galactic centers; and far-infrared observations.

  12. Astrophysics: Stars fight back

    NASA Astrophysics Data System (ADS)

    Hopkins, Philip F.

    2014-12-01

    Galaxies contain fewer stars than predicted. The discovery of a massive galactic outflow of molecular gas in a compact galaxy, which forms stars 100 times faster than the Milky Way, may help to explain why. See Letter p.68

  13. 'Polaris, Mark Kummerfeldt's Star, and My Star.'

    ERIC Educational Resources Information Center

    McLure, John W.

    1984-01-01

    In most astronomy courses, descriptions of stars and constellations reveal the western European origins of the astronomers who named them. However, it is suggested that a study of non-western views be incorporated into astronomy curricula. Descriptions of various stars and constellations from different cultures and instructional strategies are…

  14. Integrated Design for Marketing and Manufacturing team: An examination of LA-ICP-AES in a mobile configuration. Final report

    SciTech Connect

    Not Available

    1994-05-01

    The Department of Energy (DOE) has identified the need for field-deployable elemental analysis devices that are safer, faster, and less expensive than the fixed laboratory procedures now used to screen hazardous waste sites. As a response to this need, the Technology Integration Program (TIP) created a mobile, field-deployable laser ablation-inductively coupled plasma-atomic emission spectrometry (LA-ICP-AES) sampling and analysis prototype. Although the elemental. screening prototype has been successfully field-tested, continued marketing and technical development efforts are required to transfer LA-ICP-AES technology to the commercial sector. TIP established and supported a student research and design group called the Integrated Design for Marketing and Manufacturing (IDMM) team to advance the technology transfer of mobile, field-deployable LA-ICP-AES. The IDMM team developed a conceptual design (which is detailed in this report) for a mobile, field-deployable LA-ICP-AES sampling and analysis system, and reports the following findings: Mobile, field-deployable LA-ICP-AES is commercially viable. Eventual regulatory acceptance of field-deployable LA-ICP-AES, while not a simple process, is likely. Further refinement of certain processes and components of LA-ICP-AES will enhance the device`s sensitivity and accuracy.

  15. Validation of the French version of the Acceptability E-scale (AES) for mental E-health systems.

    PubMed

    Micoulaud-Franchi, Jean-Arthur; Sauteraud, Alain; Olive, Jérôme; Sagaspe, Patricia; Bioulac, Stéphanie; Philip, Pierre

    2016-03-30

    Despite the increasing use of E-health systems for mental-health organizations, there is a lack of psychometric tools to evaluate their acceptability by patients with mental disorders. Thus, this study aimed to translate and validate a French version of the Acceptability E-scale (AES), a 6-item self-reported questionnaire that evaluates the extent to which patients find E-health systems acceptable. A forward-backward translation of the AES was performed. The psychometric properties of the French AES version, with construct validity, internal structural validity and external validity (Pearson's coefficient between AES scores and depression symptoms on the Beck Depression Inventory II) were analyzed. In a sample of 178 patients (mean age=46.51 years, SD=12.91 years), the validation process revealed satisfactory psychometric properties: factor analysis revealed two factors: "Satisfaction" (3 items) and "Usability" (3 items) and Cronbach's alpha was 0.7. No significant relation was found between AES scores and depression symptoms. The French version of the AES revealed a two-factor scale that differs from the original version. In line with the importance of acceptability in mental health and with a view to E-health systems for patients with mental disorders, the use of the AES in psychiatry may provide important information on acceptability (i.e., satisfaction and usability).

  16. The Nature of Magnetic Chemically Peculiar Stars Phenomenon and the Origin of Lithium

    NASA Astrophysics Data System (ADS)

    Gopka, V. F.; Shavrina, A. V.; Yushchenko, A. V.; Yushchenko, V. A.

    understanding of the evolutionary status of young objects at the stage before the main-sequence, the progenitors of MCP stars, such as the Herbig AeBe stars. The observational data for Herbig AeBe stars (and for T Tauri stars with Herbig AeBe properties continuing in the region of stars with masses less than 2 Msun.) indicate the existence of young stars surrounded by accretion disks with typical outflow along the magnetic field lines of the disk. It was pointed by Grinin & Tambovtseva (2012) and now can be explained in the framework of our model of MCP stars (Gopka et al., 2010). On the other hand, the binary systems containing a NS companion and the detectable lithium, were really identified by Martin et al. (1994) and Rebolo et al. (1995).

  17. Desktop system for accounting, audit, and research in A&E.

    PubMed

    Taylor, C J; Brain, S G; Bull, F; Crosby, A C; Ferguson, D G

    1997-03-01

    The development of a database for audit, research, and accounting in accident and emergency (A&E) is described. The system uses a desktop computer, an optical scanner, sophisticated optical mark reader software, and workload management data. The system is highly flexible, easy to use, and at a cost of around 16,000 pounds affordable for larger departments wishing to move towards accounting. For smaller departments, it may be an alternative to full computerisation.

  18. The stability of calibration standards for ICP/AES analysis: Six-month study

    SciTech Connect

    Huff, E.A.; Huff, D.R.

    1992-05-01

    The stability of instrument calibration standards for Inductively Coupled Plasma/Atomic Emission Spectrometric (ICP/AES) analysis was studied over a six-month period. Data were obtained as functions of analyte concentration, acid type, and acidity. The impact of acid concentration on signal-to-background ratios (S/B) was also assessed. The results show that analytes maintain their integrity over extended periods with appropriate inorganic acid preservatives. Thus, frequent standard preparations become unnecessary to obtain valid analytical data.

  19. A versatile substrate design for LEED and AES studies in uhv.

    NASA Technical Reports Server (NTRS)

    Holloway, P. H.; Hudson, J. B.

    1972-01-01

    A substrate design is described that incorporates a single crystal disk into an electrically isolated, electron bombardment heated mount. Electron and photon leakage from the bombarding filament are prevented, and LEED and AES may be used at elevated temperatures. A cold finger, thermally coupled to the mount, decreases the time lost between cleaning the crystal and cooling it to the desired observation temperature. The cold finger also allows observation at temperatures below ambient.

  20. Chromospheres of Coronal Stars

    NASA Technical Reports Server (NTRS)

    Linsky, Jeffrey L.; Wood, Brian E.

    1996-01-01

    We summarize the main results obtained from the analysis of ultraviolet emission line profiles of coronal late-type stars observed with the Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope. The excellent GHRS spectra provide new information on magnetohydrodynamic phenomena in the chromospheres and transition regions of these stars. One exciting new result is the discovery of broad components in the transition region lines of active stars that we believe provide evidence for microflare heating in these stars.

  1. Dibaryons in neutron stars

    NASA Technical Reports Server (NTRS)

    Olinto, Angela V.; Haensel, Pawel; Frieman, Joshua A.

    1991-01-01

    The effects are studied of H-dibaryons on the structure of neutron stars. It was found that H particles could be present in neutron stars for a wide range of dibaryon masses. The appearance of dibaryons softens the equations of state, lowers the maximum neutron star mass, and affects the transport properties of dense matter. The parameter space is constrained for dibaryons by requiring that a 1.44 solar mass neutron star be gravitationally stable.

  2. Reconstituting the epidemic history of mono lineage of HIV-1 CRF01_AE in Guizhou province, Southern China.

    PubMed

    Zeng, Haiyan; Sun, Binlian; Li, Lingnuo; Li, Yanpeng; Liu, Yong; Xiao, Yao; Jiang, Yan; Yang, Rongge

    2014-08-01

    Guizhou province, located between border provinces and Central province of China, plays a crucial role in the transmission of HIV-1, implying it is important to monitor the epidemic of HIV-1 in this region. Available HIV-1 infected patients' plasma (n=78) were collected from Tongren city, Eastern Guizhou. Full-length gag, partial pol and env gene sequences were amplified and analyzed using phylogenetic, recombinant and Bayesian molecular clock approaches. Phylogenetic and recombinant analyses showed that CRF01_AE predominated among injecting drug users and heterosexuals in Tongren city with 85.9% proportion, it was followed by B' (5.1%), CRF07_BC (3.8%), CRF08_BC (3.8%), and B (1.3%). Moreover, 98.5% of CRF01_AE strains belonged to the distinct lineage CRF01_AE-v previously found in Guangxi province. To infer the most probable origin of CRF01_AE-v in Guizhou province, we download all available full length of CRF01_AE gag, pol and env gene region sequences from China in Los Alamos HIV sequence database. Phylodynamic and phylogeographic analyses revealed that the expanding CRF01_AE-v epidemic in Guizhou province was the result of local epidemic driven by multiple independent introductions of CRF01_AE-v strains from Guangxi province in early 2000s. High prevalence of CRF01_AE in Guizhou province may bridge the epidemic to Central China. It provides a new insight for the understanding of HIV-1 epidemic in Guizhou province and makes the evolutionary history of CRF01_AE in China more intact.

  3. Secretome of transmissible Pseudomonas aeruginosa AES-1R grown in a cystic fibrosis lung-like environment.

    PubMed

    Scott, Nichollas E; Hare, Nathan J; White, Melanie Y; Manos, Jim; Cordwell, Stuart J

    2013-12-01

    Pseudomonas aeruginosa is the predominant cause of mortality in patients with cystic fibrosis (CF). We examined the secretome of an acute, transmissible CF P. aeruginosa (Australian epidemic strain 1-R; AES-1R) compared with laboratory-adapted PAO1. Culture supernatant proteins from rich (LB) and minimal (M9) media were compared using 2-DE and 2DLC-MS/MS, which revealed elevated abundance of PasP protease and absence of AprA protease in AES-1R. CF lung-like artificial sputum medium (ASMDM) contains serum and mucin that generally preclude proteomics of secreted proteins. ASMDM culture supernatants were subjected to 2DLC-MS/MS, which allowed the identification of 57 P. aeruginosa proteins, and qualitative spectral counting was used to estimate relative abundance. AES-1R-specific AES_7139 and PasP were more abundant in AES-1R ASMDM culture supernatants, while AprA could only be identified in PAO1. Relative quantitation was performed using selected reaction monitoring. Significantly elevated levels of PasP, LasB, chitin-binding protein (CbpD), and PA4495 were identified in AES-1R ASMDM supernatants. Quantitative PCR showed elevated pasP in AES-1R during early (18 h) ASMDM growth, while no evidence of aprA expression could be observed. Genomic screening of CF isolates revealed aes_7139 was present in all AES-1 and one pair of sequential nonepidemic isolates. Secreted proteins may be crucial in aiding CF-associated P. aeruginosa to establish infection and for adaptation to the CF lung. PMID:23991618

  4. On the molecular structure of the amylopectin fraction isolated from "high-amylose" ae maize starches.

    PubMed

    Peymanpour, Ghazal; Marcone, Massimo; Ragaee, Sanaa; Tetlow, Ian; Lane, Christopher C; Seetharaman, Koushik; Bertoft, Eric

    2016-10-01

    The amylopectin fractions from starch of a series of amylose-extender (ae) maize samples (HYLON(®) V, VII and VIII starches) were isolated and analysed for their molecular composition and structure. The fractions from all samples contained both a high and a low molecular weight fraction (HMF and LMF), of which LMF increased with the amylose content of the starch and appeared to have substantially more of long chains than HMF. A normal amylose-containing maize starch (NMS), which served as a reference sample, contained very little LMF, which suggested that LMF was the inherent result of the effect of the loss of starch branching enzyme IIb activity in the ae mutants. Clusters were isolated from the amylopectin fractions using Bacillus amyloliquefaciens α-amylase, which effectively hydrolyses long internal chain segments between clusters. During the hydrolysis process, clearly more of small dextrins were released from the ae starches in comparison to NMS. It appeared that some of these small dextrins did not precipitate in methanol together with the majority of the clusters. Nevertheless, isolated clusters from the HYLON starch samples were smaller than in NMS and the clusters possessed a lower density of branches with longer chains. The composition of small, branched building blocks was also clearly different: HYLON starch samples possessed much more of single-branched blocks and less multiple-branched blocks than NMS. PMID:27296443

  5. A Procedure to Determine the Optimal Sensor Positions for Locating AE Sources in Rock Samples

    NASA Astrophysics Data System (ADS)

    Duca, S.; Occhiena, C.; Sambuelli, L.

    2015-03-01

    Within a research work aimed to better understand frost weathering mechanisms of rocks, laboratory tests have been designed to specifically assess a theoretical model of crack propagation due to ice segregation process in water-saturated and thermally microcracked cubic samples of Arolla gneiss. As the formation and growth of microcracks during freezing tests on rock material is accompanied by a sudden release of stored elastic energy, the propagation of elastic waves can be detected, at the laboratory scale, by acoustic emission (AE) sensors. The AE receiver array geometry is a sensitive factor influencing source location errors, for it can greatly amplify the effect of small measurement errors. Despite the large literature on the AE source location, little attention, to our knowledge, has been paid to the description of the experimental design phase. As a consequence, the criteria for sensor positioning are often not declared and not related to location accuracy. In the present paper, a tool for the identification of the optimal sensor position on a cubic shape rock specimen is presented. The optimal receiver configuration is chosen by studying the condition numbers of each of the kernel matrices, used for inverting the arrival time and finding the source location, and obtained for properly selected combinations between sensors and sources positions.

  6. Applications of high resolution ICP-AES in the nuclear industry

    SciTech Connect

    Johnson, S.G.; Giglio, J.J.; Goodall, P.S.; Cummings, D.G.

    1998-07-01

    Application of high resolution ICP-AES to selected problems of importance in the nuclear industry is a growing field. The advantages in sample preparation time, waste minimization and equipment cost are considerable. Two examples of these advantages are presented in this paper, burnup analysis of spent fuel and analysis of major uranium isotopes. The determination of burnup, an indicator of fuel cycle efficiency, has been accomplished by the determination of {sup 139}La by high resolution inductively coupled plasma atomic emission spectroscopy (HR-ICP-AES). Solutions of digested samples of reactor fuel rods were introduced into a shielded glovebox housing an inductively coupled plasma (ICP) and the resulting atomic emission transmitted to a high resolution spectrometer by a 31 meter fiber optic bundle. Total and isotopic U determination by thermal ionization mass spectrometry (TIMS) is presented to allow for the calculation of burnup for the samples. This method of burnup determination reduces the time, material, sample handling and waste generated associated with typical burnup determinations which require separation of lanthanum from the other fission products with high specific activities. Work concerning an alternative burnup indicator, {sup 236}U, is also presented for comparison. The determination of {sup 235}U:{sup 238}U isotope ratios in U-Zr fuel alloys is also presented to demonstrate the versatility of HR-ICP-AES.

  7. LINFLUX-AE: A Turbomachinery Aeroelastic Code Based on a 3-D Linearized Euler Solver

    NASA Technical Reports Server (NTRS)

    Reddy, T. S. R.; Bakhle, M. A.; Trudell, J. J.; Mehmed, O.; Stefko, G. L.

    2004-01-01

    This report describes the development and validation of LINFLUX-AE, a turbomachinery aeroelastic code based on the linearized unsteady 3-D Euler solver, LINFLUX. A helical fan with flat plate geometry is selected as the test case for numerical validation. The steady solution required by LINFLUX is obtained from the nonlinear Euler/Navier Stokes solver TURBO-AE. The report briefly describes the salient features of LINFLUX and the details of the aeroelastic extension. The aeroelastic formulation is based on a modal approach. An eigenvalue formulation is used for flutter analysis. The unsteady aerodynamic forces required for flutter are obtained by running LINFLUX for each mode, interblade phase angle and frequency of interest. The unsteady aerodynamic forces for forced response analysis are obtained from LINFLUX for the prescribed excitation, interblade phase angle, and frequency. The forced response amplitude is calculated from the modal summation of the generalized displacements. The unsteady pressures, work done per cycle, eigenvalues and forced response amplitudes obtained from LINFLUX are compared with those obtained from LINSUB, TURBO-AE, ASTROP2, and ANSYS.

  8. Finite element modelling of ultrasound, with reference to transducers and AE waves.

    PubMed

    Hill, R; Forsyth, S A; Macey, P

    2004-04-01

    Finite element (FE) modelling has a role to play in simulating elastic wave propagation associated with structural vibrations, acoustic phenomena and ultrasound problems. In this work we have used the PAFEC software [PAFEC finite element software PACSYS, Strelley Hall, Nottingham, NG8 6PE, UK]. With the advent of increased computer power and greater availability of software these simulations have become more readily available and will provide improved insight into wave propagation problems. Simulations have been undertaken of transient wave propagation in steel plates with an attached simple resonant transducer. This simulates acoustic emission (AE) propagation in plate like structures relevant to many industrial applications. Simulations for short propagation distances suggest the resonant transducer voltage signal carries information on the plate-waves propagating in the structure, overlaid with the piezoelectric resonance and some information might be extracted from the transducer signal. Looking at the wave propagation information alone, a great deal of variability is seen in the displacement profile for different source types, orientations and locations. Although users have expressed a need for calibration of the AE detection process, this idea remains problematic since the complete generation and detection system has the features of a chaotic system. Using FE modelling a method of "point calibration" might be available, for some specific AE applications such as crack growth along known paths. PMID:15047294

  9. Towards leakage resiliency: memristor-based AES design for differential power attack mitigation

    NASA Astrophysics Data System (ADS)

    Khedkar, Ganesh; Donahue, Colin; Kudithipudi, Dhireesha

    2014-05-01

    Side-channel attacks (SCAs), specifically differential power attacks (DPA), target hardware vulnerabilities of cryptosystems. Next generation computing systems, integrated with emerging technologies such as RRAM, offer unique opportunities to mitigate DPAs with their inherent device characteristics. We propose two different approaches to mitigate DPA attacks using memristive hardware. The first approach, obfuscates the power profile using dual RRAM modules. The power profile stays almost uniform for any given data access. This is achieved by realizing a memory and its complementary module in RRAM hardware. Balancing logic, which ensures the parallel access, is implemented in CMOS. The power consumed with the dual-RRAM balancing is an order lower than the corresponding pure CMOS implementation. The second exploratory approach, uses a novel neuromemristive architecture to compute an AES transformation and mitigate DPAs. Both the proposed approaches were tested on a 128-bit AES algorithm. A customized simulation framework, integrating CAD tools, is developed to mount the DPA attacks. In both the designs, the attack mounted on the baseline architectures (CMOS only) was successful and full key was recovered. However, DPA attacks mounted on the dual RRAM modules and neuromemristive hardware modules of an AES cryptoprocessor yielded no successful keys, demonstrating their resiliency to DPA attacks.

  10. An AES chip with DPA resistance using hardware-based random order execution

    NASA Astrophysics Data System (ADS)

    Bo, Yu; Xiangyu, Li; Cong, Chen; Yihe, Sun; Liji, Wu; Xiangmin, Zhang

    2012-06-01

    This paper presents an AES (advanced encryption standard) chip that combats differential power analysis (DPA) side-channel attack through hardware-based random order execution. Both decryption and encryption procedures of an AES are implemented on the chip. A fine-grained dataflow architecture is proposed, which dynamically exploits intrinsic byte-level independence in the algorithm. A novel circuit called an HMF (Hold-Match-Fetch) unit is proposed for random control, which randomly sets execution orders for concurrent operations. The AES chip was manufactured in SMIC 0.18 μm technology. The average energy for encrypting one group of plain texts (128 bits secrete keys) is 19 nJ. The core area is 0.43 mm2. A sophisticated experimental setup was built to test the DPA resistance. Measurement-based experimental results show that one byte of a secret key cannot be disclosed from our chip under random mode after 64000 power traces were used in the DPA attack. Compared with the corresponding fixed order execution, the hardware based random order execution is improved by at least 21 times the DPA resistance.

  11. America's Star Libraries

    ERIC Educational Resources Information Center

    Lyons, Ray; Lance, Keith Curry

    2009-01-01

    "Library Journal"'s new national rating of public libraries, the "LJ" Index of Public Library Service, identifies 256 "star" libraries. It rates 7,115 public libraries. The top libraries in each group get five, four, or three Michelin guide-like stars. All included libraries, stars or not, can use their scores to learn from their peers and improve…

  12. Managing the star performer.

    PubMed

    Hills, Laura

    2013-01-01

    Our culture seems to be endlessly fascinated with its stars in entertainment, athletics, politics, and business, and holds fast to the idea that extraordinary talent accounts for an individual's extraordinary performance. At first glance, managing a star performer in your medical practice may seem like it would be an easy task. However, there's much more to managing a star performer than many practice managers realize. The concern is how to keep the star performer happy and functioning at a high level without detriment to the rest of the medical practice team. This article offers tips for practice managers who manage star performers. It explores ways to keep the star performer motivated, while at the same time helping the star performer to meld into the existing medical practice team. This article suggests strategies for redefining the star performer's role, for holding the star performer accountable for his or her behavior, and for coaching the star performer. Finally, this article offers practical tips for keeping the star performer during trying times, for identifying and cultivating new star performers, and for managing medical practice prima donnas. PMID:23767124

  13. Ae4 (Slc4a9) is an electroneutral monovalent cation-dependent Cl-/HCO3- exchanger.

    PubMed

    Peña-Münzenmayer, Gaspar; George, Alvin T; Shull, Gary E; Melvin, James E; Catalán, Marcelo A

    2016-05-01

    Ae4 (Slc4a9) belongs to the Slc4a family of Cl(-)/HCO3 (-) exchangers and Na(+)-HCO3 (-) cotransporters, but its ion transport cycle is poorly understood. In this study, we find that native Ae4 activity in mouse salivary gland acinar cells supports Na(+)-dependent Cl(-)/HCO3 (-) exchange that is comparable with that obtained upon heterologous expression of mouse Ae4 and human AE4 in CHO-K1 cells. Additionally, whole cell recordings and ion concentration measurements demonstrate that Na(+) is transported by Ae4 in the same direction as HCO3 (-) (and opposite to that of Cl(-)) and that ion transport is not associated with changes in membrane potential. We also find that Ae4 can mediate Na(+)-HCO3 (-) cotransport-like activity under Cl(-)-free conditions. However, whole cell recordings show that this apparent Na(+)-HCO3 (-) cotransport activity is in fact electroneutral HCO3 (-)/Na(+)-HCO3 (-) exchange. Although the Ae4 anion exchanger is thought to regulate intracellular Cl(-) concentration in exocrine gland acinar cells, our thermodynamic calculations predict that the intracellular Na(+), Cl(-), and HCO3 (-) concentrations required for Ae4-mediated Cl(-) influx differ markedly from those reported for acinar secretory cells at rest or under sustained stimulation. Given that K(+) ions share many properties with Na(+) ions and reach intracellular concentrations of 140-150 mM (essentially the same as extracellular [Na(+)]), we hypothesize that Ae4 could mediate K(+)-dependent Cl(-)/HCO3 (-) exchange. Indeed, we find that Ae4 mediates Cl(-)/HCO3 (-) exchange activity in the presence of K(+) as well as Cs(+), Li(+), and Rb(+) In summary, our results strongly suggest that Ae4 is an electroneutral Cl(-)/nonselective cation-HCO3 (-) exchanger. We postulate that the physiological role of Ae4 in secretory cells is to promote Cl(-) influx in exchange for K(+)(Na(+)) and HCO3 (-) ions.

  14. Low Cost Design of an Advanced Encryption Standard (AES) Processor Using a New Common-Subexpression-Elimination Algorithm

    NASA Astrophysics Data System (ADS)

    Chen, Ming-Chih; Hsiao, Shen-Fu

    In this paper, we propose an area-efficient design of Advanced Encryption Standard (AES) processor by applying a new common-expression-elimination (CSE) method to the sub-functions of various transformations required in AES. The proposed method reduces the area cost of realizing the sub-functions by extracting the common factors in the bit-level XOR/AND-based sum-of-product expressions of these sub-functions using a new CSE algorithm. Cell-based implementation results show that the AES processor with our proposed CSE method has significant area improvement compared with previous designs.

  15. Ae4 (Slc4a9) is an electroneutral monovalent cation-dependent Cl−/HCO3− exchanger

    PubMed Central

    Peña-Münzenmayer, Gaspar; George, Alvin T.; Shull, Gary E.; Melvin, James E.

    2016-01-01

    Ae4 (Slc4a9) belongs to the Slc4a family of Cl−/HCO3− exchangers and Na+-HCO3− cotransporters, but its ion transport cycle is poorly understood. In this study, we find that native Ae4 activity in mouse salivary gland acinar cells supports Na+-dependent Cl−/HCO3− exchange that is comparable with that obtained upon heterologous expression of mouse Ae4 and human AE4 in CHO-K1 cells. Additionally, whole cell recordings and ion concentration measurements demonstrate that Na+ is transported by Ae4 in the same direction as HCO3− (and opposite to that of Cl−) and that ion transport is not associated with changes in membrane potential. We also find that Ae4 can mediate Na+-HCO3− cotransport–like activity under Cl−-free conditions. However, whole cell recordings show that this apparent Na+-HCO3− cotransport activity is in fact electroneutral HCO3−/Na+-HCO3− exchange. Although the Ae4 anion exchanger is thought to regulate intracellular Cl− concentration in exocrine gland acinar cells, our thermodynamic calculations predict that the intracellular Na+, Cl−, and HCO3− concentrations required for Ae4-mediated Cl− influx differ markedly from those reported for acinar secretory cells at rest or under sustained stimulation. Given that K+ ions share many properties with Na+ ions and reach intracellular concentrations of 140–150 mM (essentially the same as extracellular [Na+]), we hypothesize that Ae4 could mediate K+-dependent Cl−/HCO3− exchange. Indeed, we find that Ae4 mediates Cl−/HCO3− exchange activity in the presence of K+ as well as Cs+, Li+, and Rb+. In summary, our results strongly suggest that Ae4 is an electroneutral Cl−/nonselective cation–HCO3− exchanger. We postulate that the physiological role of Ae4 in secretory cells is to promote Cl− influx in exchange for K+(Na+) and HCO3− ions. PMID:27114614

  16. AE-941, a multifunctional antiangiogenic compound: trials in renal cell carcinoma.

    PubMed

    Bukowski, Ronald M

    2003-08-01

    The therapy of renal cell carcinoma remains a challenge for medical oncologists and urologists. During the past 10 years, the molecular abnormalities occurring in various subtypes of renal cancer, such as clear cell renal carcinoma, have been well described. The genetic abnormalities found in clear cell tumours involve chromosome 3p and, additionally, hypermethylation of the von Hippel-Lindau (VHL) gene can be detected. The VHL protein is involved in the angiogenic cascade in non-hypoxic conditions, and the possible role of mutant or hypermethylated VHL protein in promoting angiogenesis is, therefore, of interest. The majority of patients with renal cell carcinoma who receive treatment, such as IL-2 and/or IFN, fail and develop progressive disease. Therapy is therefore inadequate and novel approaches, such as those inhibiting angiogenesis, are of interest. The agent AE-941 (Neovostat trade mark; AEterna) was developed based on the observation that shark cartilage may contain biologically active inhibitors of angiogenesis. A variety of in vitro and in vivo activities of this preparation have been identified. At the molecular level, AE-941 appears to exhibit four different potential mechanisms of action: modulation of matrix proteases; inhibition of vascular endothelial growth factor binding to its receptor; induction of endothelial cell apoptosis; and stimulation of angiostatin production. The antitumour effects of AE-941 are seen in multiple murine models and involve not only effects on primary tumour growth but also on development of metastases. AE-941 is administered orally and has an excellent toxicity profile. Of interest are the findings in patients with renal cell carcinoma. Preliminary trials in this setting have suggested that responses to AE-941 occur and that patients receiving higher doses of this agent may have improved survival. Based on these preliminary data, a large, multi-institutional, randomised, Phase III trial of this agent has now been

  17. Flow sorting of C-genome chromosomes from wild relatives of wheat Aegilops markgrafii, Ae. triuncialis and Ae. cylindrica, and their molecular organization

    PubMed Central

    Molnár, István; Vrána, Jan; Farkas, András; Kubaláková, Marie; Cseh, András; Molnár-Láng, Márta; Doležel, Jaroslav

    2015-01-01

    Background and Aims Aegilops markgrafii (CC) and its natural hybrids Ae. triuncialis (UtUtCtCt) and Ae. cylindrica (DcDcCcCc) represent a rich reservoir of useful genes for improvement of bread wheat (Triticum aestivum), but the limited information available on their genome structure and the shortage of molecular (cyto-) genetic tools hamper the utilization of the extant genetic diversity. This study provides the complete karyotypes in the three species obtained after fluorescent in situ hybridization (FISH) with repetitive DNA probes, and evaluates the potential of flow cytometric chromosome sorting. Methods The flow karyotypes obtained after the analysis of 4',6-diamidino-2-phenylindole (DAPI)-stained chromosomes were characterized and the chromosome content of the peaks on the flow karyotypes was determined by FISH. Twenty-nine conserved orthologous set (COS) markers covering all seven wheat homoeologous chromosome groups were used for PCR with DNA amplified from flow-sorted chromosomes and genomic DNA. Key Results FISH with repetitive DNA probes revealed that chromosomes 4C, 5C, 7Ct, T6UtS.6UtL-5CtL, 1Cc and 5Dc could be sorted with purities ranging from 66 to 91 %, while the remaining chromosomes could be sorted in groups of 2–5. This identified a partial wheat–C-genome homology for group 4 and 5 chromosomes. In addition, 1C chromosomes were homologous with group 1 of wheat; a small segment from group 2 indicated 1C–2C rearrangement. An extensively rearranged structure of chromosome 7C relative to wheat was also detected. Conclusions The possibility of purifying Aegilops chromosomes provides an attractive opportunity to investigate the structure and evolution of the Aegilops C genome and to develop molecular tools to facilitate the identification of alien chromatin and support alien introgression breeding in bread wheat. PMID:26043745

  18. Validation of the new trapped environment AE9/AP9/SPM at low Earth orbit

    NASA Astrophysics Data System (ADS)

    Badavi, Francis F.

    2014-09-01

    The completion of the international space station (ISS) in 2011 has provided the space research community an ideal proving ground for future long duration human activities in space. Ionizing radiation measurements in ISS form the ideal tool for the validation of radiation environmental models, nuclear transport codes and nuclear reaction cross sections. Indeed, prior measurements on the space transportation system (STS; shuttle) provided vital information impacting both the environmental models and the nuclear transport code developments by indicating the need for an improved dynamic model of the low Earth orbit (LEO) trapped environment. Additional studies using thermo-luminescent detector (TLD), tissue equivalent proportional counter (TEPC) area monitors, and computer aided design (CAD) model of earlier ISS configurations, confirmed STS observations that, as input, computational dosimetry requires an environmental model with dynamic and directional (anisotropic) behavior, as well as an accurate six degree of freedom (DOF) definition of the vehicle attitude and orientation along the orbit of ISS. At LEO, a vehicle encounters exposure from trapped particles and attenuated galactic cosmic rays (GCR). Within the trapped field, a challenge arises from properly estimating the amount of exposure acquired. There exist a number of models to define the intensities of the trapped particles during the solar quiet and active times. At active times, solar energetic particles (SEP) generated by solar flare or coronal mass ejection (CME) also contribute to the exposure at high northern and southern latitudes. Among the more established trapped models are the historic and popular AE8/AP8, dating back to the 1980s, the historic and less popular CRRES electron/proton, dating back to 1990s and the recently released AE9/AP9/SPM. The AE9/AP9/SPM model is a major improvement over the older AE8/AP8 and CRRES models. This model is derived from numerous measurements acquired over four

  19. Ponderable soliton stars

    NASA Technical Reports Server (NTRS)

    Chiu, Hong-Yee

    1990-01-01

    The theory of Lee and Pang (1987), who obtained solutions for soliton stars composed of zero-temperature fermions and bosons, is applied here to quark soliton stars. Model soliton stars based on a simple physical model of the proton are computed, and the properties of the solitons are discussed, including the important problem of the existence of a limiting mass and thus the possible formation of black holes of primordial origin. It is shown that there is a definite mass limit for ponderable soliton stars, so that during cooling a soliton star might reach a stage beyond which no equilibrium configuration exists and the soliton star probably will collapse to become a black hole. The radiation of ponderable soliton stars may alter the short-wavelength character of the cosmic background radiation, and may be observed as highly redshifted objects at z of about 100,000.

  20. Star field simulator

    NASA Technical Reports Server (NTRS)

    1985-01-01

    A Star Field Simulator has been developed to serve as a source of radiation for the ASTRO Star Tracker. The star tracker and simulator are components of a motion compensation test facility located at Marshall Space Flight Center in Huntsville, Alabama. Preflight tests and simulations using various levels of guide stars are performed in the test facility to establish performance of the motion compensation system before being used in a flight environment. The ASTRO Star Tracker operates over a wide dynamic range of irradiance corresponding to visual stellar magnitudes of -0.8 to 8. A minimum of three simulated guide stars with variable magnitudes are needed to fully test the Star Tracker performance under simulated mission conditions.

  1. A study of the initial oxidation of evaporated thin films of aluminum by AES, ELS, and ESD

    NASA Technical Reports Server (NTRS)

    Bujor, M.; Larson, L. A.; Poppa, H.

    1982-01-01

    The room temperature, low pressure, oxidation of evaporated aluminum thin films has been studied by AES, ELS, and ESD. ESD was the most sensitive of the three methods to characterize a clean aluminum surface. Two oxidation stages were distinguished in the 0-3000 L oxygen exposure range. Between 0 and 50 L, the chemisorption of oxygen atoms was characterized by a fast decrease of the 67 eV AES Al peak and the 10 eV surface plasmon peak, and by a simultaneous increase of the oxygen AES and ESD signals. After 50 L, a change in slope in all AES and ESD signal variations was attributed to the slow growth of a thin layer of aluminum oxide, which after 3000 L was still only a few angstroms thick.

  2. An unsupervised pattern recognition approach for AE data originating from fatigue tests on polymer-composite materials

    NASA Astrophysics Data System (ADS)

    Doan, D. D.; Ramasso, E.; Placet, V.; Zhang, S.; Boubakar, L.; Zerhouni, N.

    2015-12-01

    This work investigates acoustic emission generated during tension fatigue tests carried out on a carbon fiber reinforced polymer (CFRP) composite specimen. Since massive fatigue data processing, especially noise reduction, remains an important challenge in AE data analysis, a Mahalanobis distance-based noise modeling has been proposed in the present work to tackle this problem. A sequential feature selection based on Davies-Bouldin index has been implemented for fast dimensionality reduction. An unsupervised classifier offline-learned from quasi-static data is then used to classify the data to different AE sources with the possibility to dynamically accommodate with unseen ones. With an efficient proposed noise removal and automatic separation of AE events, this pattern discovery procedure provides an insight into fatigue damage development in composites in the presence of millions of AE events.

  3. The L7Ae protein binds to two kink-turns in the Pyrococcus furiosus RNase P RNA.

    PubMed

    Lai, Stella M; Lai, Lien B; Foster, Mark P; Gopalan, Venkat

    2014-12-01

    The RNA-binding protein L7Ae, known for its role in translation (as part of ribosomes) and RNA modification (as part of sn/oRNPs), has also been identified as a subunit of archaeal RNase P, a ribonucleoprotein complex that employs an RNA catalyst for the Mg(2+)-dependent 5' maturation of tRNAs. To better understand the assembly and catalysis of archaeal RNase P, we used a site-specific hydroxyl radical-mediated footprinting strategy to pinpoint the binding sites of Pyrococcus furiosus (Pfu) L7Ae on its cognate RNase P RNA (RPR). L7Ae derivatives with single-Cys substitutions at residues in the predicted RNA-binding interface (K42C/C71V, R46C/C71V, V95C/C71V) were modified with an iron complex of EDTA-2-aminoethyl 2-pyridyl disulfide. Upon addition of hydrogen peroxide and ascorbate, these L7Ae-tethered nucleases were expected to cleave the RPR at nucleotides proximal to the EDTA-Fe-modified residues. Indeed, footprinting experiments with an enzyme assembled with the Pfu RPR and five protein cofactors (POP5, RPP21, RPP29, RPP30 and L7Ae-EDTA-Fe) revealed specific RNA cleavages, localizing the binding sites of L7Ae to the RPR's catalytic and specificity domains. These results support the presence of two kink-turns, the structural motifs recognized by L7Ae, in distinct functional domains of the RPR and suggest testable mechanisms by which L7Ae contributes to RNase P catalysis.

  4. IrAE – an asparaginyl endopeptidase (legumain) in the gut of the hard tick Ixodes ricinus

    PubMed Central

    Sojka, Daniel; Hajdušek, Ondřej; Dvořák, Jan; Sajid, Mohammed; Franta, Zdeněk; Schneider, Eric L.; Craik, Charles S.; Vancová, Marie; Burešová, Veronika; Bogyo, Matthew; Sexton, Kelly B.; McKerrow, James H.; Caffrey, Conor R.; Kopáček, Petr

    2008-01-01

    Ticks are ectoparasitic blood-feeders and important vectors for pathogens including arboviruses, rickettsiae, spirochetes and protozoa. As obligate blood-feeders, one possible strategy to retard disease transmission is disruption of the parasite’s ability to digest host proteins. However, the constituent peptidases in the parasite gut and their potential interplay in the digestion of the blood meal are poorly understood. We have characterized a novel asparaginyl endopeptidase (legumain) from the hard tick Ixodes ricinus (termed IrAE), which is the first such characterization of a clan CD family C13 cysteine peptidase (protease) in arthropods. By RT-PCR of different tissues, IrAE mRNA was only expressed in the tick gut. Indirect immunofluorescence and electron microscopy localized IrAE in the digestive vesicles of gut cells and within the peritrophic matrix. IrAE was functionally expressed in Pichia pastoris and reacted with a specific peptidyl fluorogenic substrate, and acyloxymethyl ketone and aza-asparagine Michael acceptor inhibitors. IrAE activity was unstable at pH ≥ 6.0 and was shown to have a strict specificity for asparagine at P1 using a positional scanning synthetic combinatorial library. The enzyme hydrolyzed protein substrates with a pH optimum of 4.5, consistent with the pH of gut cell digestive vesicles. Thus, IrAE cleaved the major protein of the blood meal, hemoglobin, to a predominant peptide of 4 kDa. Also, IrAE trans-processed and activated the zymogen form of Schistosoma mansoni cathepsin B1 – an enzyme contributing to hemoglobin digestion in the gut of that bloodfluke. The possible functions of IrAE in the gut digestive processes of I. ricinus are compared with those suggested for other hematophagous parasites. PMID:17336985

  5. Houttuynoids A-E, anti-herpes simplex virus active flavonoids with novel skeletons from Houttuynia cordata.

    PubMed

    Chen, Shao-Dan; Gao, Hao; Zhu, Qin-Chang; Wang, Ya-Qi; Li, Ting; Mu, Zhen-Qiang; Wu, Hong-Ling; Peng, Tao; Yao, Xin-Sheng

    2012-04-01

    Houttuynoids A-E (1-5), a new type of flavonoid with houttuynin tethered to hyperoside, and their presumed biosynthetic precursor hyperoside (6) were isolated from the whole plant of Houttuynia cordata. Their structures were elucidated by analysis of 1D and 2D NMR. A hypothetical biogenetic pathway for houttuynoids A-E was proposed. Compounds 1-5 exhibited potent anti-HSV (herpes simplex viruses) activity. PMID:22414220

  6. Dark stars: a review.

    PubMed

    Freese, Katherine; Rindler-Daller, Tanja; Spolyar, Douglas; Valluri, Monica

    2016-06-01

    Dark stars are stellar objects made (almost entirely) of hydrogen and helium, but powered by the heat from dark matter annihilation, rather than by fusion. They are in hydrostatic and thermal equilibrium, but with an unusual power source. Weakly interacting massive particles (WIMPs), among the best candidates for dark matter, can be their own antimatter and can annihilate inside the star, thereby providing a heat source. Although dark matter constitutes only [Formula: see text]0.1% of the stellar mass, this amount is sufficient to power the star for millions to billions of years. Thus, the first phase of stellar evolution in the history of the Universe may have been dark stars. We review how dark stars come into existence, how they grow as long as dark matter fuel persists, and their stellar structure and evolution. The studies were done in two different ways, first assuming polytropic interiors and more recently using the MESA stellar evolution code; the basic results are the same. Dark stars are giant, puffy (∼10 AU) and cool (surface temperatures  ∼10 000 K) objects. We follow the evolution of dark stars from their inception at  ∼[Formula: see text] as they accrete mass from their surroundings to become supermassive stars, some even reaching masses  >[Formula: see text] and luminosities  >[Formula: see text], making them detectable with the upcoming James Webb Space Telescope. Once the dark matter runs out and the dark star dies, it may collapse to a black hole; thus dark stars may provide seeds for the supermassive black holes observed throughout the Universe and at early times. Other sites for dark star formation may exist in the Universe today in regions of high dark matter density such as the centers of galaxies. The current review briefly discusses dark stars existing today, but focuses on the early generation of dark stars. PMID:27214049

  7. Dark stars: a review

    NASA Astrophysics Data System (ADS)

    Freese, Katherine; Rindler-Daller, Tanja; Spolyar, Douglas; Valluri, Monica

    2016-06-01

    Dark stars are stellar objects made (almost entirely) of hydrogen and helium, but powered by the heat from dark matter annihilation, rather than by fusion. They are in hydrostatic and thermal equilibrium, but with an unusual power source. Weakly interacting massive particles (WIMPs), among the best candidates for dark matter, can be their own antimatter and can annihilate inside the star, thereby providing a heat source. Although dark matter constitutes only ≲ 0.1% of the stellar mass, this amount is sufficient to power the star for millions to billions of years. Thus, the first phase of stellar evolution in the history of the Universe may have been dark stars. We review how dark stars come into existence, how they grow as long as dark matter fuel persists, and their stellar structure and evolution. The studies were done in two different ways, first assuming polytropic interiors and more recently using the MESA stellar evolution code; the basic results are the same. Dark stars are giant, puffy (˜10 AU) and cool (surface temperatures  ˜10 000 K) objects. We follow the evolution of dark stars from their inception at  ˜1{{M}⊙} as they accrete mass from their surroundings to become supermassive stars, some even reaching masses  >{{10}6}{{M}⊙} and luminosities  >{{10}10}{{L}⊙} , making them detectable with the upcoming James Webb Space Telescope. Once the dark matter runs out and the dark star dies, it may collapse to a black hole; thus dark stars may provide seeds for the supermassive black holes observed throughout the Universe and at early times. Other sites for dark star formation may exist in the Universe today in regions of high dark matter density such as the centers of galaxies. The current review briefly discusses dark stars existing today, but focuses on the early generation of dark stars.

  8. Dark stars: a review

    NASA Astrophysics Data System (ADS)

    Freese, Katherine; Rindler-Daller, Tanja; Spolyar, Douglas; Valluri, Monica

    2016-06-01

    Dark stars are stellar objects made (almost entirely) of hydrogen and helium, but powered by the heat from dark matter annihilation, rather than by fusion. They are in hydrostatic and thermal equilibrium, but with an unusual power source. Weakly interacting massive particles (WIMPs), among the best candidates for dark matter, can be their own antimatter and can annihilate inside the star, thereby providing a heat source. Although dark matter constitutes only ≲ 0.1% of the stellar mass, this amount is sufficient to power the star for millions to billions of years. Thus, the first phase of stellar evolution in the history of the Universe may have been dark stars. We review how dark stars come into existence, how they grow as long as dark matter fuel persists, and their stellar structure and evolution. The studies were done in two different ways, first assuming polytropic interiors and more recently using the MESA stellar evolution code; the basic results are the same. Dark stars are giant, puffy (∼10 AU) and cool (surface temperatures  ∼10 000 K) objects. We follow the evolution of dark stars from their inception at  ∼1{{M}ȯ} as they accrete mass from their surroundings to become supermassive stars, some even reaching masses  >{{10}6}{{M}ȯ} and luminosities  >{{10}10}{{L}ȯ} , making them detectable with the upcoming James Webb Space Telescope. Once the dark matter runs out and the dark star dies, it may collapse to a black hole; thus dark stars may provide seeds for the supermassive black holes observed throughout the Universe and at early times. Other sites for dark star formation may exist in the Universe today in regions of high dark matter density such as the centers of galaxies. The current review briefly discusses dark stars existing today, but focuses on the early generation of dark stars.

  9. Intergalactic Star Formation

    NASA Astrophysics Data System (ADS)

    Boquien, Médéric

    2007-11-01

    The work presented here is about star formation in the unusual environment of collisional debris studied for the first time as such. These peculiar regions have an interstellar medium, and in particular a metallicity, similar to that of star forming regions in galactic discs while not undergoing similar environment effects such as density waves in the spiral arms for instance. This study has been conducted with a selection of exceptional systems that have ejected large quantities of gas into the intergalactic medium while also showing some intergalactic star forming regions. Principal Investigator as well as archive spectroscopy and imaging from multi-wavelength observations ranging from far ultraviolet to mid-infrared have been used. Withal a model has been built in order to reproduce the spectral energy distributions of intergalactic star forming regions and constrain the star formation histories, their extinctions and their fraction of stars coming from the parent galaxies' discs. Comparisons have been performed on the estimation of star formation rates between infrared, Halpha and ultraviolet wavelengths. This thesis has brought the following main new results: * some regions seem to be deprived of any old stellar population, and these are ideal laboratories in which to study star formation ; * the mid-infrared star formation rate estimator is as reliable as it is in spiral galaxies ; * the scatter in the estimation of star formation rates in various bands is similar to that of spiral galaxies and is mainly due to age effects ; * the combination of the extinction uncorrected Halpha line with mid-infrared yields a good estimation of the actual star formation rate ; * an important part of star formation, which can be as high as 85%, takes place in the intergalactic medium showing that in a young universe, in which this type of system is much more common than in the nearby universe, star formation from collisional debris can be an important factor of enrichment of

  10. Dark stars: a review.

    PubMed

    Freese, Katherine; Rindler-Daller, Tanja; Spolyar, Douglas; Valluri, Monica

    2016-06-01

    Dark stars are stellar objects made (almost entirely) of hydrogen and helium, but powered by the heat from dark matter annihilation, rather than by fusion. They are in hydrostatic and thermal equilibrium, but with an unusual power source. Weakly interacting massive particles (WIMPs), among the best candidates for dark matter, can be their own antimatter and can annihilate inside the star, thereby providing a heat source. Although dark matter constitutes only [Formula: see text]0.1% of the stellar mass, this amount is sufficient to power the star for millions to billions of years. Thus, the first phase of stellar evolution in the history of the Universe may have been dark stars. We review how dark stars come into existence, how they grow as long as dark matter fuel persists, and their stellar structure and evolution. The studies were done in two different ways, first assuming polytropic interiors and more recently using the MESA stellar evolution code; the basic results are the same. Dark stars are giant, puffy (∼10 AU) and cool (surface temperatures  ∼10 000 K) objects. We follow the evolution of dark stars from their inception at  ∼[Formula: see text] as they accrete mass from their surroundings to become supermassive stars, some even reaching masses  >[Formula: see text] and luminosities  >[Formula: see text], making them detectable with the upcoming James Webb Space Telescope. Once the dark matter runs out and the dark star dies, it may collapse to a black hole; thus dark stars may provide seeds for the supermassive black holes observed throughout the Universe and at early times. Other sites for dark star formation may exist in the Universe today in regions of high dark matter density such as the centers of galaxies. The current review briefly discusses dark stars existing today, but focuses on the early generation of dark stars.

  11. Star formation regions in galaxies: Star complexes and spiral arms

    NASA Astrophysics Data System (ADS)

    Efremov, Iurii N.

    This book describes observational data on star formation regions (from young star clusters to spiral arms) in the Milky Way and other galaxies. It is concluded that not only high-luminosity stars but also star clusters and associations are forming together in vast complexes. It is claimed that these complexes are the primary, fundamental entities of star formation.

  12. Ae4 (Slc4a9) Anion Exchanger Drives Cl- Uptake-dependent Fluid Secretion by Mouse Submandibular Gland Acinar Cells.

    PubMed

    Peña-Münzenmayer, Gaspar; Catalán, Marcelo A; Kondo, Yusuke; Jaramillo, Yasna; Liu, Frances; Shull, Gary E; Melvin, James E

    2015-04-24

    Transcellular Cl(-) movement across acinar cells is the rate-limiting step for salivary gland fluid secretion. Basolateral Nkcc1 Na(+)-K(+)-2Cl(-) cotransporters play a critical role in fluid secretion by promoting the intracellular accumulation of Cl(-) above its equilibrium potential. However, salivation is only partially abolished in the absence of Nkcc1 cotransporter activity, suggesting that another Cl(-) uptake pathway concentrates Cl(-) ions in acinar cells. To identify alternative molecular mechanisms, we studied mice lacking Ae2 and Ae4 Cl(-)/HCO3 (-) exchangers. We found that salivation stimulated by muscarinic and β-adrenergic receptor agonists was normal in the submandibular glands of Ae2(-/-) mice. In contrast, saliva secretion was reduced by 35% in Ae4(-/-) mice. The decrease in salivation was not related to loss of Na(+)-K(+)-2Cl(-) cotransporter or Na(+)/H(+) exchanger activity in Ae4(-/-) mice but correlated with reduced Cl(-) uptake during β-adrenergic receptor activation of cAMP signaling. Direct measurements of Cl(-)/HCO3 (-) exchanger activity revealed that HCO3 (-)-dependent Cl(-) uptake was reduced in the acinar cells of Ae2(-/-) and Ae4(-/-) mice. Moreover, Cl(-)/HCO3 (-) exchanger activity was nearly abolished in double Ae4/Ae2 knock-out mice, suggesting that most of the Cl(-)/HCO3 (-) exchanger activity in submandibular acinar cells depends on Ae2 and Ae4 expression. In conclusion, both Ae2 and Ae4 anion exchangers are functionally expressed in submandibular acinar cells; however, only Ae4 expression appears to be important for cAMP-dependent regulation of fluid secretion.

  13. Three-dimensional model for the human Cl-/HCO3- exchanger, AE1, by homology to the E. coli ClC protein.

    PubMed

    Bonar, Pamela; Schneider, Hans-Peter; Becker, Holger M; Deitmer, Joachim W; Casey, Joseph R

    2013-07-24

    AE1 mediates electroneutral 1:1 exchange of bicarbonate for chloride across the plasma membrane of erythrocytes and type A cells of the renal collecting duct. No high-resolution structure is available for the AE1 membrane domain, which alone is required for its transport activity. A recent electron microscopy structure of the AE1 membrane domain was proposed to have a similar protein fold to ClC chloride channels. We developed a three-dimensional homology model of the AE1 membrane domain, using the Escherichia coli ClC channel structure as a template. This model agrees well with a long list of biochemically established spatial constraints for AE1. To investigate the AE1 transport mechanism, we created point mutations in regions corresponding to E. coli ClC transport mechanism residues. When expressed in HEK293 cells, several mutants had Cl(-)/HCO3(-) exchange rates significantly different from that of wild-type AE1. When further assessed in Xenopus laevis oocytes, there were significant changes in the transport activity of several AE1 point mutants as assessed by changes in pH. None of the mutants, however, added an electrogenic component to AE1 transport activity. This indicates that the AE1 point mutants altered the transport activity of AE1, without changing its electrogenicity and stoichiometry. The homology model successfully identified residues in AE1 that are critical to AE1 transport activity. Thus, we conclude that AE1 has a similar protein fold to ClC chloride channels.

  14. Conceptual design of the AE481 Demon Remotely Piloted Vehicle (RPV)

    NASA Technical Reports Server (NTRS)

    Hailes, Chris; Kolver, Jill; Nestor, Julie; Patterson, Mike; Selow, Jan; Sagdeo, Pradip; Katz, Kenneth

    1994-01-01

    This project report presents a conceptual design for a high speed remotely piloted vehicle (RPV). The AE481 Demon RPV is capable of performing video reconnaissance missions and electronic jamming over hostile territory. The RPV cruises at a speed of Mach 0.8 and an altitude of 300 feet above the ground throughout its mission. It incorporates a rocket assisted takeoff and a parachute-airbag landing. Missions are preprogrammed, but in-flight changes are possible. The Demon is the answer to a military need for a high speed, low altitude RPV. The design methods, onboard systems, and avionics payload are discussed in this conceptual design report along with economic viability.

  15. Low-dimensional chaos in magnetospheric activity from AE time series

    NASA Technical Reports Server (NTRS)

    Vassiliadis, D. V.; Sharma, A. S.; Eastman, T. E.; Papadopoulos, K.

    1990-01-01

    The magnetospheric response to the solar-wind input, as represented by the time-series measurements of the auroral electrojet (AE) index, has been examined using phase-space reconstruction techniques. The system was found to behave as a low-dimensional chaotic system with a fractal dimension of 3.6 and has Kolmogorov entropy less than 0.2/min. These indicate that the dynamics of the system can be adequately described by four independent variables, and that the corresponding intrinsic time scale is of the order of 5 min. The relevance of the results to magnetospheric modeling is discussed.

  16. Determination of soil micronutrients (Fe, Cu, Mn, B) extracted by Mehlich 3 using MP-AES

    NASA Astrophysics Data System (ADS)

    Krebstein, Kadri; Tõnutare, Tõnu; Rodima, Ako; Kõlli, Raimo; Künnapas, Allan; Rebane, Jaanus; Penu, Priit; Vennik, Kersti; Soobik, Liina

    2015-04-01

    The total concentration of micronutrients in soils is not a good predictor of its bioavailability and solubility. Therefore, during the decades several methods for the determination of plant availability and extractable fraction of micro- and macronutrients in soil were developed. Among several methods Mehlich 3 is the most appropriate due to its suitability for extracting soil micro- and macronutrients simultaneously. The AAS (atomic absorption spectroscopic) and ICP (inductively coupled plasma) methods are widely used for the analysis of microelements today. In 2011 the third method was added to this list with the appearance of the microwave plasma atomic emission spectrometer (MP-AES). This multielemental analytical equipment has a high potential in the soil analysis. Up to now there have been made some experiments for the use of MP-AES in soil and geological material analysis. But there is no information about the analysis of soil micronutrients extracted according to Mehlich 3 method and determined with the MP-AES. Due to the differences in atomization conditions the different emission and absorption lines are used in different instrumental methods. Therefore it is very important to choose the most suitable emission lines and the best atomization conditions. From the analytical viewpoint it is important to get coincidental results with other instrumental methods and from the agronomical point of view it is important to know the difference between AAS and ICP methods. For the experiment 51 soil samples were used. The samples were collected from A horizons of agricultural lands. The pH range was from 4.7 to 7.5 and organic matter content from 1.4 to 7.8%. The content of Mehlich 3 extractable micronutrients was determined using ICP and MP instrumental methods. The micronutrient contents ranged as follows: Fe - from 170 to 470 mg kg-1, Mn - from 5 to 190 mg kg-1, Cu - from 0.3 to 4.5 mg kg-1, B - from 0.2 to 2.1 mg kg-1. The optimal instrumental settings for iron

  17. Microstructural Evolution of a C-Mn Steel During Hot Compression Above the Ae3

    NASA Astrophysics Data System (ADS)

    Aranas, Clodualdo M.; Shen, Yu-Jack; Rodrigues, Samuel F.; Jonas, John J.

    2016-09-01

    In order to study the microstructural evolution during deformation, hot compression tests were carried out on a 0.06 wt pct C-0.30 wt pct Mn-0.01 wt pct Si steel at temperatures above the Ae3. The volume fraction of ferrite produced dynamically increased with the applied strain and decreased with increasing temperature. The present data are used to generate an isothermal strain-temperature-transformation diagram based on the applied strain. Results of this type can be employed to predict the effect of dynamic transformation during thermomechanical processing.

  18. Estimation of The Radiation Environment Based On The NASA Ap-8 and Ae-8 Models

    NASA Technical Reports Server (NTRS)

    Morton, Thomas; Lyons, Valerie (Technical Monitor)

    2002-01-01

    In this paper, we discuss the earth's trapped radiation environment, as described by the NASA models AP-8 and AE-8. We include a description of the sources and structure of the trapped radiation belts, and their dependence on external factors. After describing how to use the models to predict the environment, we present data from various space missions, and compare those data to the models. This shows the limits and strengths of the models. Finally, we describe alternative models of the trapped radiation belts, and discuss why they have not been widely adopted yet.

  19. Prediction of AU, AL, and AE indices using solar wind parameters

    NASA Astrophysics Data System (ADS)

    Luo, B.; Li, X.; Temerin, M. A.; Liu, S.

    2013-12-01

    An empirical model that predicts the AU index, a measure of the Earth's east electrojet, derived from magnetometers in the Northern hemisphere, is introduced. In addition, we have improved the previous AL model (Li et al., 2007) and have combined it with the AU model to produce an AE model. All models are based on upstream solar wind and interplanetary magnetic field parameters that have been propagated to the magnetopause by a simple ballistic propagation scheme for the years 1995 to 2001. The AU model predicts the 10-min averaged AU index for the seven years 1995-2001 with a prediction efficiency (PE) of 0.716, a linear correlation coefficient (LC) between the AU index and the model of 0.846, and a root mean square (RMS) error of 39.3 nT. We have updated the AL model introduced in Li et al. [2007] using the same prediction functions used to predict AU but with different parameters. The new AL model predicts the seven year AL index with a PE of 0.715, an LC of 0.846, and an RMS error of 81.6 nT. Using AE = AU-AL, the AE index is predicted with a PE of 0.788, an LC of 0.888, and an RMS error of 95.7 nT. The better PE and LC of the AE model over AU and AL models is because AU and AL are better correlated then their prediction errors. It is also found that: (1) The F10.7 index modulates the growth of auroral electrojet indices; (2) AU and AL behave differently during geomagnetic storm main phases. AU can drop to a low level while the magnitude of AL does not drop as much; (3) the longer-averaged auroral electrojets indices can be predicted very well but shorter timescale variations are much less predictable; (4) auroral electrojet activity is strongly dependent on the upstream solar wind velocity and the interplanetary magnetic field but is only weakly dependent on the solar wind density.

  20. [Artificial neural network applied for spectral overlap interference correction in ICP-AES].

    PubMed

    Zhang, Z; Liu, S; Zeng, X

    1997-10-01

    A back-propagation artificial neural network (BP-ANN) has been applied to correcting spectral overlap interference in inductively coupled plasma atomic emission spectrometry (ICP-AES). Some network parameters including the range of input values and training sequence for training patterns presented to the network were discussed using simulated Ce 413.380nm and Pr 413.380nm line profiles. Results show that the noise in simulated mixture spectra will slow down the network convergence and has more influence on network prediction. PMID:15810366

  1. Reniochalistatins A-E, cyclic peptides from the marine sponge Reniochalina stalagmitis.

    PubMed

    Zhan, Kai-Xuan; Jiao, Wei-Hua; Yang, Fan; Li, Jing; Wang, Shu-Ping; Li, Yu-Shan; Han, Bing-Nan; Lin, Hou-Wen

    2014-12-26

    Five new cyclic peptides (including four heptapeptides and one octapeptide), reniochalistatins A-E (1-5), were isolated and characterized from the marine sponge Reniochalina stalagmitis collected off Yongxing Island in the South China Sea. Their structures were assigned on the basis of HRESIMS, 1D and 2D NMR spectroscopic data, and MALDI-TOF/TOF data for sequence analysis. The absolute configurations of all of the amino acid residues were determined using chiral-phase HPLC and Marfey's analysis. The cyclic octapeptide reniochalistatin E showed biological activity in various cytotoxicity assays employing different tumor cell lines (RPMI-8226, MGC-803, HL-60, HepG2, and HeLa).

  2. Indimicins A-E, Bisindole Alkaloids from the Deep-Sea-Derived Streptomyces sp. SCSIO 03032.

    PubMed

    Zhang, Wenjun; Ma, Liang; Li, Sumei; Liu, Zhong; Chen, Yuchan; Zhang, Haibo; Zhang, Guangtao; Zhang, Qingbo; Tian, Xinpeng; Yuan, Chengshan; Zhang, Si; Zhang, Weimin; Zhang, Changsheng

    2014-08-22

    Five new bisindole alkaloids, indimicins A-E (1-5), bearing a unique 1',3'-dimethyl-2'-hydroindole moiety, were isolated from the marine-derived Streptomyces sp. SCSIO 03032, along with two new compounds, lynamicins F and G (6 and 7). Their planar structures were elucidated by detailed interpretation of their MS and NMR spectroscopic data, and the absolute configurations were determined by X-ray crystallographic analysis (for 1), comparison of CD spectra (for 2-4), and quantum chemical calculations (for 5). Indimicin B (2) exhibited moderate cytotoxic activity toward the MCF-7 cell line.

  3. STAR in CTO PCI: When is STAR not a star?

    PubMed

    Hira, Ravi S; Dean, Larry S

    2016-04-01

    Subintimal tracking and reentry (STAR) has been used as a bailout strategy and involves an uncontrolled dissection and recanalization into the distal lumen to reestablish vessel patency. In the current study, thrombolysis in myocardial infarction (TIMI) flow < 3 was the only variable which they found to be significantly associated with restenosis and reocclusion after stent placement. It may be reasonable to consider second generation drug eluting stent placement in patients receiving STAR that have TIMI 3 flow, however, this should only be done if there is no compromise of major side branches. If unsure, we recommend to perform balloon angioplasty without stenting.

  4. The First Stars

    NASA Astrophysics Data System (ADS)

    Yoshida, Naoki

    2010-10-01

    The standard cosmological model predicts that the first cosmological objects are formed when the age of the universe is a few hundred million years. Recent theoretical studies and numerical simulations consistently suggest that the first objects are very massive primordial stars. We introduce the key physics and explain why the first stars are thought to be massive, rather than to be low-mass stars. The state-of-the-art simulations include all the relevant atomic and molecular physics to follow the thermal evolution of a prestellar gas cloud to very high ``stellar'' densities. Evolutionary calculations of the primordial stars suggest the formation of massive blackholes in the early universe. Finally, we show the results from high-resolution simulations of star formation in a low-metallicity gas. Vigorous fragmentation is triggered in a star-forming gas cloud at a metallicity of as low as Z = 10-5Zsolar.

  5. Primary care units in A&E departments in North Thames in the 1990s: initial experience and future implications.

    PubMed Central

    Freeman, G K; Meakin, R P; Lawrenson, R A; Leydon, G M; Craig, G

    1999-01-01

    BACKGROUND: In 1992, the Tomlinson Report recommended a shift from secondary to primary care, including specific primary care provision in accident and emergency (A&E) departments. Availability of short-term so-called Tomlinson moneys allowed a number of experimental services. A study of the experience of A&E-based staff is reported to assist general practitioners (GPs) and purchasers and identify areas for further research. AIMS: To find the number and scope of primary care facilities in A&E services in North Thames; to find factors encouraging or inhibiting the setting-up of a successful service; to examine the views of a range of A&E staff including GPs, consultants, and nurses; and to suggest directions for more specific research. METHOD: A postal questionnaire was sent to all North Thames A&E departments, and an interview study of staff in one unit was arranged, leading to a questionnaire study of all GPs employed in North Thames primary care services in A&E. This was followed by interviews of staff members in five contrasting primary care units in A&E. RESULTS: By mid-1995, at least 16 of the 33 North Thames A&E departments ran a primary care service. Seven mainly employed GPs, the others employed nurse practitioners (NPs). Problems for GPs included unclear role definition and their non-availability at times of highest patient demand. GPs' reasons for working in A&E sometimes differed from the aims of primary care in an A&E service. Staff interviews revealed differing views about their role and about use of triage protocols. Ethnicity data were being collected, but not yet being used, to improve service to patients. CONCLUSIONS: A number of benefits follow the introduction of primary care practitioners into A&E. Different models have evolved, with a variety of GP and NP staffing arrangements according to local ideas and priorities. There is some confusion over whether these services aim to improve A&E-based care or to divert it to general practice. Cost

  6. Strange nonchaotic stars.

    PubMed

    Lindner, John F; Kohar, Vivek; Kia, Behnam; Hippke, Michael; Learned, John G; Ditto, William L

    2015-02-01

    The unprecedented light curves of the Kepler space telescope document how the brightness of some stars pulsates at primary and secondary frequencies whose ratios are near the golden mean, the most irrational number. A nonlinear dynamical system driven by an irrational ratio of frequencies generically exhibits a strange but nonchaotic attractor. For Kepler's "golden" stars, we present evidence of the first observation of strange nonchaotic dynamics in nature outside the laboratory. This discovery could aid the classification and detailed modeling of variable stars.

  7. Massive soliton stars

    NASA Technical Reports Server (NTRS)

    Chiu, Hong-Yee

    1990-01-01

    The structure of nontopological solutions of Einstein field equations as proposed by Friedberg, Lee, and Pang (1987) is examined. This analysis incorporates finite temperature effects and pair creation. Quarks are assumed to be the only species that exist in interior of soliton stars. The possibility of primordial creation of soliton stars in the incomplete decay of the degenerate vacuum in early universe is explored. Because of dominance of pair creation inside soliton stars, the luminosity of soliton stars is not determined by its radiative transfer characteristics, and the surface temperature of soliton stars can be the same as its interior temperature. It is possible that soliton stars are intense X-ray radiators at large distances. Soliton stars are nearly 100 percent efficient energy converters, converting the rest energy of baryons entering the interior into radiation. It is possible that a sizable number of baryons may also be trapped inside soliton stars during early epochs of the universe. In addition, if soliton stars exist they could assume the role played by massive black holes in galactic centers.

  8. Delta Scuti stars: Theory

    SciTech Connect

    Guzik, J.A.

    1998-03-01

    The purpose of asteroseismology is not only to derive the internal structure of individual stars from their observed oscillation frequencies, but also to test and extend one`s understanding of the physics of matter under the extremes of temperature, density, and pressure found in stellar interiors. In this review, the author hopes to point out what one can learn about the Sun by studying {delta} Scuti stars, as well as what one can learn about stars more massive or evolved than the Sun. He discusses some of the difficulties in theoretical approaches to asteroseismology for {delta} Scuti stars, using FG Vir, {delta} Scuti, and CD-24{degree} 7599 as examples.

  9. Massive soliton stars

    SciTech Connect

    Chiu, Hongyee )

    1990-05-01

    The structure of nontopological solutions of Einstein field equations as proposed by Friedberg, Lee, and Pang (1987) is examined. This analysis incorporates finite temperature effects and pair creation. Quarks are assumed to be the only species that exist in interior of soliton stars. The possibility of primordial creation of soliton stars in the incomplete decay of the degenerate vacuum in early universe is explored. Because of dominance of pair creation inside soliton stars, the luminosity of soliton stars is not determined by its radiative transfer characteristics, and the surface temperature of soliton stars can be the same as its interior temperature. It is possible that soliton stars are intense X-ray radiators at large distances. Soliton stars are nearly 100 percent efficient energy converters, converting the rest energy of baryons entering the interior into radiation. It is possible that a sizable number of baryons may also be trapped inside soliton stars during early epochs of the universe. In addition, if soliton stars exist they could assume the role played by massive black holes in galactic centers. 27 refs.

  10. Introduction to neutron stars

    SciTech Connect

    Lattimer, James M.

    2015-02-24

    Neutron stars contain the densest form of matter in the present universe. General relativity and causality set important constraints to their compactness. In addition, analytic GR solutions are useful in understanding the relationships that exist among the maximum mass, radii, moments of inertia, and tidal Love numbers of neutron stars, all of which are accessible to observation. Some of these relations are independent of the underlying dense matter equation of state, while others are very sensitive to the equation of state. Recent observations of neutron stars from pulsar timing, quiescent X-ray emission from binaries, and Type I X-ray bursts can set important constraints on the structure of neutron stars and the underlying equation of state. In addition, measurements of thermal radiation from neutron stars has uncovered the possible existence of neutron and proton superfluidity/superconductivity in the core of a neutron star, as well as offering powerful evidence that typical neutron stars have significant crusts. These observations impose constraints on the existence of strange quark matter stars, and limit the possibility that abundant deconfined quark matter or hyperons exist in the cores of neutron stars.

  11. Strange Nonchaotic Stars

    NASA Astrophysics Data System (ADS)

    Lindner, John F.; Kohar, Vivek; Kia, Behnam; Hippke, Michael; Learned, John G.; Ditto, William L.

    2015-08-01

    Exploiting the unprecedented capabilities of the planet-hunting Kepler space telescope, which stared at 150 000 stars for four years, we discuss recent evidence that certain stars dim and brighten in complex patterns with fractal features. Such stars pulsate at primary and secondary frequencies whose ratios are near the famous golden mean, the most irrational number. A nonlinear system driven by an irrational ratio of frequencies is generically attracted toward a “strange” behavior that is geometrically fractal without displaying the “butterfly effect” of chaos. Strange nonchaotic attractors have been observed in laboratory experiments and have been hypothesized to describe the electrochemical activity of the brain, but a bluish white star 16 000 light years from Earth in the constellation Lyra may manifest, in the scale-free distribution of its minor frequency components, the first strange nonchaotic attractor observed in the wild. The recognition of stellar strange nonchaotic dynamics may improve the classification of these stars and refine the physical modeling of their interiors. We also discuss nonlinear analysis of other RR Lyrae stars in Kepler field of view and discuss some toy models for modeling these stars.References: 1) Hippke, Michael, et al. "Pulsation period variations in the RRc Lyrae star KIC 5520878." The Astrophysical Journal 798.1 (2015): 42.2) Lindner, John F., et al. "Strange nonchaotic stars." Phys. Rev. Lett. 114, 054101 (2015)

  12. Probing the ejecta of evolved massive stars in transition. A VLT/SINFONI K-band survey

    NASA Astrophysics Data System (ADS)

    Oksala, M. E.; Kraus, M.; Cidale, L. S.; Muratore, M. F.; Borges Fernandes, M.

    2013-10-01

    Massive evolved stars in transition phases, such as luminous blue variables (LBVs), B[e] supergiants (B[e]SGs), and yellow hypergiants (YHGs), are not well understood, and yet crucial steps in determining accurate stellar and galactic evolution models. The circumstellar environments of these stars reveal their mass-loss history, identifying clues to both their individual evolutionary status and the connection between objects of different phases. Here we present a survey of 25 such evolved massive stars (16 B[e]SGs, 6 LBVs, 2 YHGs, and 1 Peculiar Oe star), observed in the K-band with the Spectrograph for INtegral Field Observation in the Near-Infrared (SINFONI; R = 4500) on the ESO VLT UT4 8 m telescope. The sample can be split into two categories based on spectral morphology: one group includes all of the B[e]SGs, the Peculiar Oe star, and two of the LBVs, while the other includes the YHGs and the rest of the LBVs. The difference in LBV spectral appearance is due to some objects being in a quiescent phase and some objects being in an active or outburst phase. CO emission features are found in 13 of our targets, with first time detections for MWC 137, LHA 120-S 35, and LHA 115-S 65. From model fits to the CO band heads, the emitting regions appear to be detached from the stellar surface. Each star with 12CO features also shows 13CO emission, signaling an evolved nature. Based on the level of 13C enrichment, we conclude that many of the B[e]SGs are likely in a pre-Red Supergiant phase of their evolution. There appears to be a lower luminosity limit of log L/L⊙ = 5.0 below which CO is not detected. The lack of CO features in several high luminosity B[e]SGs and variability in others suggests that they may in fact be LBV candidates, strengthening the connection between these two very similar transition phases. Based on observations at the European Southern Observatory, Paranal, under program IDs 384.D-1078(A) and 088.D-0442(B).Tables 3-5, and Fig. 6 are available in

  13. Combinations of 148 navigation stars and the star tracker

    NASA Technical Reports Server (NTRS)

    Duncan, R.

    1980-01-01

    The angular separation of all star combinations for 148 nav star on the onboard software for space transportation system-3 flight and following missions is presented as well as the separation of each pair that satisfies the viewing constraints of using both star trackers simultaneously. Tables show (1) shuttle star catalog 1980 star position in M 1950 coordinates; (2) two star combination of 148 nav stars; and (3) summary of two star-combinations of the star tracker 5 deg filter. These 148 stars present 10,875 combinations. For the star tracker filters of plus or minus 5 deg, there are 875 combinations. Formalhaut (nav star 26) has the best number of combinations, which is 33.

  14. Targeted disruption of the Cl−/HCO3− exchanger Ae2 results in osteopetrosis in mice

    PubMed Central

    Josephsen, Kaj; Praetorius, Jeppe; Frische, Sebastian; Gawenis, Lara R.; Kwon, Tae-Hwan; Agre, Peter; Nielsen, Søren; Fejerskov, Ole

    2009-01-01

    Osteoclasts are multinucleated bone-resorbing cells responsible for constant remodeling of bone tissue and for maintaining calcium homeostasis. The osteoclast creates an enclosed space, a lacuna, between their ruffled border membrane and the mineralized bone. They extrude H+ and Cl− into these lacunae by the combined action of vesicular H+-ATPases and ClC-7 exchangers to dissolve the hydroxyapatite of bone matrix. Along with intracellular production of H+ and HCO3− by carbonic anhydrase II, the H+-ATPases and ClC-7 exchangers seems prerequisite for bone resorption, because genetic disruption of either of these proteins leads to osteopetrosis. We aimed to complete the molecular model for lacunar acidification, hypothesizing that a HCO3− extruding and Cl− loading anion exchange protein (Ae) would be necessary to sustain bone resorption. The Ae proteins can provide both intracellular pH neutrality and serve as cellular entry mechanism for Cl− during bone resorption. Immunohistochemistry revealed that Ae2 is exclusively expressed at the contra-lacunar plasma membrane domain of mouse osteoclast. Severe osteopetrosis was encountered in Ae2 knockout (Ae2−/−) mice where the skeletal development was impaired with a higher diffuse radio-density on x-ray examination and the bone marrow cavity was occupied by irregular bone speculae. Furthermore, osteoclasts in Ae2−/− mice were dramatically enlarged and fail to form the normal ruffled border facing the lacunae. Thus, Ae2 is likely to be an essential component of the bone resorption mechanism in osteoclasts. PMID:19164575

  15. Effect of Deep Cryogenic Treatment on Microstructure and Properties of AE42 Mg Alloy

    NASA Astrophysics Data System (ADS)

    Bhale, Pranav; Shastri, H.; Mondal, A. K.; Masanta, M.; Kumar, S.

    2016-07-01

    The effect of deep cryogenic treatment (DCT) on microstructure and mechanical properties including corrosion behavior of the squeeze-cast AE42 alloy has been investigated. For comparison, the same has also been studied on the untreated alloy. Both the untreated and deep cryogenic-treated (DCTed) alloys comprised α-Mg and Al4RE phases. Volume fraction of the Al4RE phase in the AE42 alloy reduced gradually following DCT carried out from 4 to 16 h. Ductility and UTS increase significantly with a marginal increase in YS of all the DCTed alloys. The improvement was attributed to the dissolution of the brittle Al4RE phase following DCT. Among the alloys employed, the best tensile properties were obtained for the 16-h DCT alloy due to its lowest content of the brittle Al4RE phase. Creep resistance of the DCTed alloys was lower than that of the untreated alloy owing to the presence of less amount of thermally stable intermetallic Al4RE phase. Wear resistance of the alloy reduces following DCT due to reduced hardness of the DCTed alloys. The untreated alloy exhibits the best corrosion resistance, whereas poor corrosion resistance of the DCTed alloys is attributed to the reduced amount of Al4RE phase that fails to built a corrosion resistance barrier.

  16. Hello darkness my old friend: the fading of the nearby TDE ASASSN-14ae

    NASA Astrophysics Data System (ADS)

    Brown, Jonathan S.; Shappee, Benjamin J.; Holoien, T. W.-S.; Stanek, K. Z.; Kochanek, C. S.; Prieto, J. L.

    2016-11-01

    We present late-time optical spectroscopy taken with the Large Binocular Telescope's Multi-Object Double Spectrograph, an improved All-Sky Automated Survey for SuperNovae pre-discovery non-detection, and late-time Swift observations of the nearby (d = 193 Mpc, z = 0.0436) tidal disruption event (TDE) ASASSN-14ae. Our observations span from ˜20 d before to ˜750 d after discovery. The proximity of ASASSN-14ae allows us to study the optical evolution of the flare and the transition to a host-dominated state with exceptionally high precision. We measure very weak Hα emission 300 d after discovery (LH α ≃ 4 × 1039 erg s-1) and the most stringent upper limit to date on the Hα luminosity ˜750 d after discovery (LH α ≲ 1039 erg s-1), suggesting that the optical emission arising from a TDE can vanish on a time-scale as short as 1 yr. Our results have important implications for both spectroscopic detection of TDE candidates at late times, as well as the nature of TDE host galaxies themselves.

  17. Global equatorial ionospheric vertical plasma drifts measured by the AE-E satellite

    SciTech Connect

    Fejer, B.G.; Paula, E.R. de l Heelis, R.A.

    1995-04-01

    Ion drift meter observations from the Atmospheric Explorer E satellite during the period of January 1977 to December 1979 are used to study the dependence of equatorial (dip latitudes {le}7.5{degrees}) F region vertical plasma drifts (east-west electric fields) on solar activity, season, and longitude. The satellite-observed ion drifts show large day-to-day and seasonal variations. Solar cycle effects are most pronounced near the dusk sector with a large increase of the prereversal velocity enhancement from solar minimum to maximum. The diurnal, seasonal, and solar cycle dependence of the longitudinally averaged drifts are consistent with results from the Jicamarca radar except near the June solstice when the AE-E nightime downward velocities are significantly smaller than those observed by the radar. Pronounced presunrise downward drift enhancements are often observed over a large longitudinal range but not in the Peruvian equatorial region. The satellite data indicate that longitudinal variations are largest near the June solstice, particularly near dawn and dusk but are virtually absent during equinox. The longitudinal dependence of the AE-E vertical drifts is consistent with results from ionosonde data. These measurements were also used to develop a description of equatorial F region vertical drifts in four longitudinal sectors. 17 refs., 7 figs.

  18. Hello Darkness My Old Friend: The Fading of the Nearby TDE ASASSN-14ae

    NASA Astrophysics Data System (ADS)

    Brown, Jonathan S.; Shappee, Benjamin J.; Holoien, T. W.-S.; Stanek, K. Z.; Kochanek, C. S.; Prieto, J. L.

    2016-08-01

    We present late-time optical spectroscopy taken with the Large Binocular Telescope's Multi-Object Double Spectrograph, an improved ASAS-SN pre-discovery non-detection, and late-time Swift observations of the nearby (d = 193 Mpc, z = 0.0436) tidal disruption event (TDE) ASASSN-14ae. Our observations span from ˜ 20 days before to ˜ 750 days after discovery. The proximity of ASASSN-14ae allows us to study the optical evolution of the flare and the transition to a host dominated state with exceptionally high precision. We measure very weak Hα emission 300 days after discovery (LHα ≃ 4 × 1039 ergs s-1) and the most stringent upper limit to date on the Hα luminosity ˜ 750 days after discovery (LHα ≲ 1039 ergs s-1), suggesting that the optical emission arising from a TDE can vanish on a timescale as short as 1 year. Our results have important implications for both spectroscopic detection of TDE candidates at late times, as well as the nature of TDE host galaxies themselves.

  19. Effect of Deep Cryogenic Treatment on Microstructure and Properties of AE42 Mg Alloy

    NASA Astrophysics Data System (ADS)

    Bhale, Pranav; Shastri, H.; Mondal, A. K.; Masanta, M.; Kumar, S.

    2016-09-01

    The effect of deep cryogenic treatment (DCT) on microstructure and mechanical properties including corrosion behavior of the squeeze-cast AE42 alloy has been investigated. For comparison, the same has also been studied on the untreated alloy. Both the untreated and deep cryogenic-treated (DCTed) alloys comprised α-Mg and Al4RE phases. Volume fraction of the Al4RE phase in the AE42 alloy reduced gradually following DCT carried out from 4 to 16 h. Ductility and UTS increase significantly with a marginal increase in YS of all the DCTed alloys. The improvement was attributed to the dissolution of the brittle Al4RE phase following DCT. Among the alloys employed, the best tensile properties were obtained for the 16-h DCT alloy due to its lowest content of the brittle Al4RE phase. Creep resistance of the DCTed alloys was lower than that of the untreated alloy owing to the presence of less amount of thermally stable intermetallic Al4RE phase. Wear resistance of the alloy reduces following DCT due to reduced hardness of the DCTed alloys. The untreated alloy exhibits the best corrosion resistance, whereas poor corrosion resistance of the DCTed alloys is attributed to the reduced amount of Al4RE phase that fails to built a corrosion resistance barrier.

  20. On the embedding-dimension analysis of AE and AL time series

    NASA Technical Reports Server (NTRS)

    Shan, Lin-Hua; Goertz, Christoph; Smith, Robert A.

    1991-01-01

    Several authors have employed the embedding-dimension method to analyze time series of geomagnetic indices, with differing results for the value of the correlation dimension nu. It is argued that these differences may arise from corresponding differences in the length and construction of the various data sets used. Practical application of the method to sets of discretized data requires use of a delay time scale set by the autocorrelation time of the data set. It is found that a particular data set containing 35 days of AE exhibits an autocorrelation time tau(c) longer by an order of magnitude than that of a short-duration (less than 5 days) set, raising the possibility that extant analyses of long-duration sets may have employed delay times shorter than tau(c). In addition, the power spectrum of AE reveals modulation at a period of 24 hr. A numerical experiment on the logistic map shows that such modulation introduces an extra degree of freedom in the data, resulting in an augmented correlation dimension.

  1. VizieR Online Data Catalog: Southern emission-line stars multiphotometry (de Winter+, 2001)

    NASA Astrophysics Data System (ADS)

    de Winter, D.; van den Ancker, M. E.; Maira, A.; The, P. S.; Tjin A Djie, H. R. E.; Redondo, I.; Eiroa, C.; Molster, F. J.

    2001-10-01

    This paper presents a catalogue of previously unpublished optical and infrared photometry for a sample of 162 emission-line objects and shell stars visible from the southern hemisphere. The data were obtained between 1978 and 1997 in the Walraven (WULBV), Johnson/Cousins UBV(RI)c and ESO and SAAO near-infrared (JHKLM) photometric systems. Most of the observed objects are Herbig Ae/Be (HAeBe) stars or HAeBe candidates appearing in the list of HAeBe candidates of The et al. (1994, Cat. ), although several B[e] stars, LBVs and T Tauri are also included in the sample. For many of the stars the data presented here are the first photo-electric measurements in the literature. The resulting catalogue consists of 1809 photometric measurements. Optical variability was detected in 66 out of the 116 sources that were observed more than once. 15 out of the 50 stars observed multiple times in the infrared showed variability at 2.2 microns (K band). Table 1 contains the stars identifiers, positions, types and a summary of the observational data on each star. Tables 2, 3 and 4 contain all obtained photometry in the Walraven WULBV, Johnson/Cousins UBV(RI)_c and ESO and SAAO near-infrared (JHKLM) photometric systems. (4 data files).

  2. Triggered Star Formation on the Border of the Orion-Eridanus Superbubble

    NASA Astrophysics Data System (ADS)

    Lee, Hsu-Tai; Chen, W. P.

    2009-04-01

    A census of classical T Tauri stars and Herbig Ae/Be stars has been performed around the Orion-Eridanus Superbubble that is ionized and created by the Ori OB1 association. This sample is used to study the spatial distribution of newborn stars, hence the recent star formation sequence, in the region that includes two giant molecular clouds (Orions A and B) and additional smaller clouds (NGC 2149, GN 05.51.4, VdB 64, the Crossbones, the Northern Filament, LDN 1551, LDN 1558, and LDN 1563). Most of the molecular clouds are located on the border of the Superbubble, and associated with Hα filaments and star formation activity, except the Northern Filament which is probably located outside the Superbubble. This suggests that while star formation progresses from the oldest Ori OB1a subgroup to 1b, 1c, and 1d, the Superbubble compresses and initiates starbirth in clouds such as NGC 2149, GN 05.51.4, VdB 64, and the Crossbones, which are located more than 100 pc away from the center of the Superbubble, and even in clouds some 200 pc away, i.e., in LDN 1551, LDN 1558, and LDN 1563. A superbubble appears to have potentially a long-range influence in triggering next-generation star formation in an OB association.

  3. HOT GAS LINES IN T TAURI STARS

    SciTech Connect

    Ardila, David R.; Herczeg, Gregory J.; Gregory, Scott G.; Hillenbrand, Lynne A.; Ingleby, Laura; Bergin, Edwin; Bethell, Thomas; Calvet, Nuria; France, Kevin; Brown, Alexander; Edwards, Suzan; Johns-Krull, Christopher; Linsky, Jeffrey L.; Yang, Hao; Valenti, Jeff A.; Abgrall, Herve; Alexander, Richard D.; Brown, Joanna M.; Espaillat, Catherine; Hussain, Gaitee; and others

    2013-07-01

    For Classical T Tauri Stars (CTTSs), the resonance doublets of N V, Si IV, and C IV, as well as the He II 1640 A line, trace hot gas flows and act as diagnostics of the accretion process. In this paper we assemble a large high-resolution, high-sensitivity data set of these lines in CTTSs and Weak T Tauri Stars (WTTSs). The sample comprises 35 stars: 1 Herbig Ae star, 28 CTTSs, and 6 WTTSs. We find that the C IV, Si IV, and N V lines in CTTSs all have similar shapes. We decompose the C IV and He II lines into broad and narrow Gaussian components (BC and NC). The most common (50%) C IV line morphology in CTTSs is that of a low-velocity NC together with a redshifted BC. For CTTSs, a strong BC is the result of the accretion process. The contribution fraction of the NC to the C IV line flux in CTTSs increases with accretion rate, from {approx}20% to up to {approx}80%. The velocity centroids of the BCs and NCs are such that V{sub BC} {approx}> 4 V{sub NC}, consistent with the predictions of the accretion shock model, in at most 12 out of 22 CTTSs. We do not find evidence of the post-shock becoming buried in the stellar photosphere due to the pressure of the accretion flow. The He II CTTSs lines are generally symmetric and narrow, with FWHM and redshifts comparable to those of WTTSs. They are less redshifted than the CTTSs C IV lines, by {approx}10 km s{sup -1}. The amount of flux in the BC of the He II line is small compared to that of the C IV line, and we show that this is consistent with models of the pre-shock column emission. Overall, the observations are consistent with the presence of multiple accretion columns with different densities or with accretion models that predict a slow-moving, low-density region in the periphery of the accretion column. For HN Tau A and RW Aur A, most of the C IV line is blueshifted suggesting that the C IV emission is produced by shocks within outflow jets. In our sample, the Herbig Ae star DX Cha is the only object for which we find a

  4. Monitoring Space Disturbances using KACST MWC detector

    NASA Astrophysics Data System (ADS)

    Maghrabi, Abdullrahman; Alenizi, Mohammed; Almuteri, Mohammed; AlDosari, Abdullah; Alshehri, Abdullah

    2016-04-01

    Forbush decreases are short term variations in cosmic ray observations due to the solar transient events such as solar flares and coronal mass ejections which affect the interplanetary field and heliospheric structure. They are defined as a sharp reduction of cosmic ray intensity followed by a gradual recovery over a period of a few days. We have constructed and operated a three layer small MultiWire Proportional Chamber (MWPC) for cosmic ray muon monitoring. The detector is located at KACST radiation detector laboratory (769 m; Rc=14.4 GV), Riyadh, Saudi Arabia. In this paper, data from this newly developed detector were used to study FD observed during 5-30 December 2015. Interplanetary data were used to characterize the solar and interplanetary conditions causing the observed FD. The obtained results were comparable with those obtained by the existed 1 m2 scintillator detector and with data obtained from different neutron monitors around the world.

  5. Trafficking defect of mutant kidney anion exchanger 1 (kAE1) proteins associated with distal renal tubular acidosis and Southeast Asian ovalocytosis.

    PubMed

    Sawasdee, Nunghathai; Udomchaiprasertkul, Wandee; Noisakran, Sansanee; Rungroj, Nanyawan; Akkarapatumwong, Varaporn; Yenchitsomanus, Pa-thai

    2006-11-24

    Compound heterozygous anion exchanger 1 (AE1) SAO/G701D mutations result in distal renal tubular acidosis with Southeast Asian ovalocytosis. Interaction, trafficking and localization of wild-type and mutant (SAO and G701D) kAE1 proteins fused with hemagglutinin, six-histidine, Myc, or green fluorescence protein (GFP) were examined in human embryonic kidney (HEK) 293 cells. When individually expressed, wild-type kAE1 was localized at cell surface while mutant kAE1 SAO and G701D were intracellularly retained. When co-expressed, wild-type kAE1 could form heterodimer with kAE1 SAO or kAE1 G701D and could rescue mutant kAE1 proteins to express on the cell surface. Co-expression of kAE1 SAO and kAE1 G701D also resulted in heterodimer formation but intracellular retention without cell surface expression, suggesting their trafficking defect and failure to rescue each other to the plasma membrane, most likely the molecular mechanism of the disease in the compound heterozygous condition. PMID:17027918

  6. GLOBAL STAR FORMATION REVISITED

    SciTech Connect

    Silk, Joseph; Norman, Colin E-mail: norman@stsci.edu

    2009-07-20

    A general treatment of disk star formation is developed from a dissipative multiphase model, with the dominant dissipation due to cloud collisions. The Schmidt-Kennicutt (SK) law emerges naturally for star-forming disks and starbursts. We predict that there should be an inverse correlation between Tully-Fisher law and SK law residuals. The model is extended to include a multiphase treatment of supernova feedback that leads to a turbulent pressure-regulated generalization of the star formation law and is applicable to gas-rich starbursts. Enhanced pressure, as expected in merger-induced star formation, enhances star formation efficiency. An upper limit is derived for the disk star formation rate in starbursts that depends on the ratio of global ISM to cloud pressures. We extend these considerations to the case where the interstellar gas pressure in the inner galaxy is dominated by outflows from a central active galactic nucleus (AGN). During massive spheroid formation, AGN-driven winds trigger star formation, resulting in enhanced supernova feedback and outflows. The outflows are comparable to the AGN-boosted star formation rate and saturate in the super-Eddington limit. Downsizing of both SMBH and spheroids is a consequence of AGN-driven positive feedback. Bondi accretion feeds the central black hole with a specific accretion rate that is proportional to the black hole mass. AGN-enhanced star formation is mediated by turbulent pressure and relates spheroid star formation rate to black hole accretion rate. The relation between black hole mass and spheroid velocity dispersion has a coefficient (Salpeter time to gas consumption time ratio) that provides an arrow of time. Highly efficient, AGN-boosted star formation can occur at high redshift.

  7. The Pistol Star

    NASA Astrophysics Data System (ADS)

    Figer, Donald F.; Najarro, Francisco; Morris, Mark; McLean, Ian S.; Geballe, Thomas R.; Ghez, Andrea M.; Langer, Norbert

    1998-10-01

    We present new near-infrared data and analysis, which indicate that the Pistol Star is one of the most luminous stars known, adding another test point for massive star formation and stellar evolution theories. We estimate an extinction of AK = 3.2 +/- 0.5 using the near-infrared colors of the star and of surrounding stars in the young Quintuplet cluster. Using our wind/atmosphere code, we find two families of models that fit the spectral energy distribution and detailed line profiles. The lower luminosity models give L = 106.6+/-0.2 L⊙ and Teff = 104.15+/-0.01 K, while the higher luminosity models give L = 107.2+/-0.2 L⊙ and Teff = 104.33+/-0.01 K; the error in luminosity assumes an uncertainty of +/-0.5 in AK, while the error in Teff is constrained by detailed line modeling. The models also reveal a helium enriched surface. As previously existing stellar evolution models do not extend to such high luminosities, we employ new evolutionary tracks for very massive stars to determine the initial mass and age of the Pistol Star, and estimate Minitial = 200-250 M⊙ and an age of 1.7-2.1 Myr. The inferred luminosity and temperature place the star in a sparsely populated zone in the H-R diagram where luminous blue variables (LBVs) are often found. This is consistent with our evolutionary models, which predict that the star is in an unstable evolutionary stage. We interpret the star and its surrounding nebula as an LBV that has recently ejected large amounts of material. Our K-band speckle-imaging data reveal the star to be single down to a projected separation of 110 AU.

  8. Star Trek in the Schools

    ERIC Educational Resources Information Center

    Journal of Aerospace Education, 1977

    1977-01-01

    Describes specific educational programs for using the Star Trek TV program from kindergarten through college. For each grade level lesson plans, ideas for incorporating Star Trek into future classes, and reports of specific programs utilizing Star Trek are provided. (SL)

  9. Observations of FK Comae stars

    NASA Technical Reports Server (NTRS)

    Bopp, B. W.

    1981-01-01

    Observations on the FK Comae stars are described. FK Com, UZ Lib and HD 199178 are compared and related as a group of stars. The crucial observational tests of the proposed evolutionary status of these stars are noted.

  10. Neutron Star Compared to Manhattan

    NASA Video Gallery

    A pulsar is a neutron star, the crushed core of a star that has exploded. Neutron stars crush half a million times more mass than Earth into a sphere no larger than Manhattan, as animated in this s...

  11. Stars and Flowers, Flowers and Stars

    NASA Astrophysics Data System (ADS)

    Minti, Hari

    2012-12-01

    The author, a graduated from the Bucharest University (1964), actually living and working in Israel, concerns his book to variable stars and flowers, two domains of his interest. The analogies includes double stars, eclipsing double stars, eclipses, Big Bang. The book contains 34 chapters, each of which concerns various relations between astronomy and other sciences and pseudosciences such as Psychology, Religion, Geology, Computers and Astrology (to which the author is not an adherent). A special part of the book is dedicated to archeoastronomy and ethnoastronomy, as well as to history of astronomy. Between the main points of interest of these parts: ancient sanctuaries in Sarmizegetusa (Dacia), Stone Henge(UK) and other. The last chapter of the book is dedicated to flowers. The book is richly illustrated. It is designed for a wide circle of readers.

  12. Implementation of the AES as a Hash Function for Confirming the Identity of Software on a Computer System

    SciTech Connect

    Hansen, Randy R.; Bass, Robert B.; Kouzes, Richard T.; Mileson, Nicholas D.

    2003-01-20

    This paper provides a brief overview of the implementation of the Advanced Encryption Standard (AES) as a hash function for confirming the identity of software resident on a computer system. The PNNL Software Authentication team chose to use a hash function to confirm software identity on a system for situations where: (1) there is limited time to perform the confirmation and (2) access to the system is restricted to keyboard or thumbwheel input and output can only be displayed on a monitor. PNNL reviewed three popular algorithms: the Secure Hash Algorithm - 1 (SHA-1), the Message Digest - 5 (MD-5), and the Advanced Encryption Standard (AES) and selected the AES to incorporate in software confirmation tool we developed. This paper gives a brief overview of the SHA-1, MD-5, and the AES and sites references for further detail. It then explains the overall processing steps of the AES to reduce a large amount of generic data-the plain text, such is present in memory and other data storage media in a computer system, to a small amount of data-the hash digest, which is a mathematically unique representation or signature of the former that could be displayed on a computer's monitor. This paper starts with a simple definition and example to illustrate the use of a hash function. It concludes with a description of how the software confirmation tool uses the hash function to confirm the identity of software on a computer system.

  13. Populations of Carbon Stars

    NASA Astrophysics Data System (ADS)

    Lloyd Evans, T.

    2011-09-01

    Carbon stars in the Galaxy do not constitute a single family, but may be divided over several types with distinctive spectroscopic and photometric properties. A subtype of the N stars, characterised by high velocities and weak CN bands, may have been captured by the Milky Way from a cannibalised dwarf galaxy.

  14. Modeling rapidly rotating stars

    NASA Astrophysics Data System (ADS)

    Rieutord, M.

    2006-06-01

    We review the quest of modeling rapidly rotating stars during the past 40 years and detail the challenges to be taken up by models facing new data from interferometry, seismology, spectroscopy... We then present the progress of the ESTER project aimed at giving a physically self-consistent model for the structure and evolution of rapidly rotating stars.

  15. Science through ARts (STAR)

    ERIC Educational Resources Information Center

    Densmore, Marycay; Kolecki, Joseph C.; Miller, Allan; Petersen, Ruth; Terrell, Mike

    2005-01-01

    Science Through ARts (STAR) is a free, international, cross-curricular program thematically aligned with "The Vision for Space Exploration," a framework of goals and objectives published by NASA in February 2004. Through the STAR program, students in grades 5 through 12 are encouraged to apply their knowledge in creative ways as they approach a…

  16. Observing Double Stars

    NASA Astrophysics Data System (ADS)

    Genet, Russell M.; Fulton, B. J.; Bianco, Federica B.; Martinez, John; Baxter, John; Brewer, Mark; Carro, Joseph; Collins, Sarah; Estrada, Chris; Johnson, Jolyon; Salam, Akash; Wallen, Vera; Warren, Naomi; Smith, Thomas C.; Armstrong, James D.; McGaughey, Steve; Pye, John; Mohanan, Kakkala; Church, Rebecca

    2012-05-01

    Double stars have been systematically observed since William Herschel initiated his program in 1779. In 1803 he reported that, to his surprise, many of the systems he had been observing for a quarter century were gravitationally bound binary stars. In 1830 the first binary orbital solution was obtained, leading eventually to the determination of stellar masses. Double star observations have been a prolific field, with observations and discoveries - often made by students and amateurs - routinely published in a number of specialized journals such as the Journal of Double Star Observations. All published double star observations from Herschel's to the present have been incorporated in the Washington Double Star Catalog. In addition to reviewing the history of visual double stars, we discuss four observational technologies and illustrate these with our own observational results from both California and Hawaii on telescopes ranging from small SCTs to the 2-meter Faulkes Telescope North on Haleakala. Two of these technologies are visual observations aimed primarily at published "hands-on" student science education, and CCD observations of both bright and very faint doubles. The other two are recent technologies that have launched a double star renaissance. These are lucky imaging and speckle interferometry, both of which can use electron-multiplying CCD cameras to allow short (30 ms or less) exposures that are read out at high speed with very low noise. Analysis of thousands of high speed exposures allows normal seeing limitations to be overcome so very close doubles can be accurately measured.

  17. Party with the Stars.

    ERIC Educational Resources Information Center

    Blaine, Lloyd

    1997-01-01

    Describes a Star Party which involves comparing the different colors of the stars, demonstrating how astronomers measure the sky with degrees, determining the cardinal direction, discussing numerous stories that ancient civilizations gave to constellations, exercising science process skills, and using science instruments. (JRH)

  18. Science Through ARts (STAR)

    NASA Technical Reports Server (NTRS)

    Kolecki, Joseph; Petersen, Ruth; Williams, Lawrence

    2002-01-01

    Science Through ARts (STAR) is an educational initiative designed to teach students through a multidisciplinary approach to learning. This presentation describes the STAR pilot project, which will use Mars exploration as the topic to be integrated. Schools from the United Kingdom, Japan, the United States, and possibly eastern Europe are expected to participate in the pilot project.

  19. PAHs in circumstellar disks around T Tauri stars

    NASA Astrophysics Data System (ADS)

    Geers, Vincent C.; Augereau, Jean-Charles; Pontoppidan, Klaus M.; Dullemond, Cornelis P.; Visser, Ruud; van Dishoeck, Ewine F.; C2d Irs Team

    We have begun to investigate the emission from Polycyclic Aromatic Hydrocarbons seen toward circumstellar disks around young low mass pre-main-sequence (T Tauri) stars, observed as part of our Spitzer Legacy program "From Molecular Cores to Planet-Forming Disks" (Evans et al. 2003). In this poster we will present some of our first Spitzer spectra of PAH features in T Tauri stars and discuss these features in the context of the disk structure and the UV radiation field needed to excite the PAH molecules. Laboratory measurements show that PAH molecules are strongly heated/excited when they absorb a single UV photon, and that they re-radiate the energy through C-H and C-C stretch and C-H bending mode transitions, in the form of infrared photons. These give rise to characteristic PAH features at 3.3, 6.2, 7.7, 8.6, 11.2 and 12.8 microns. These emission features have now been observed toward about 60% of intermediate mass Herbig Ae/Be stars with the ISO satellite (Acke & van den Ancker 2004) and for a few of these sources, ground-based spatially resolved spectroscopy has confirmed that the emission originates from the inner ~100-150 AU region around the star (Geers et al. 2004, van Boekel et al. 2004, Habart et al. 2004), so typically on the scale of circumstellar disks. Our investigation of PAHs in disks around young stars takes two approaches. On the one hand, we address the question how the PAH abundance evolves in these disks during this period of planet formation and how their presence can have an impact on the circumstellar environment. The observed PAH emission is believed to originate from the surface layers of the disk, where the large molecules / small grains are mixed with the gas. The high opacity of PAHs to FUV radiation can significantly reduce the stellar UV field in the inner parts of the disk, while at the same time, through the photo-electric effect, PAHs can provide an important heating mechanism for the gas in the surrounding environment through

  20. [A new automated method to identify emission line star from massive spectra].

    PubMed

    Pan, Jing-Chang; Zhang, Cai-Ming; Wei, Peng; Luo, A-Li; Zhao, Yong-Heng

    2012-06-01

    Stellar spectra are characterized by obvious absorption lines or absorption bands, while those with emission lines are usually special stars such as cataclysmic variable stars (CVs), HerbigAe/Be etc. The further study of this kind of spectra is meaningful. The present paper proposed a new method to identify emission line stars (ELS) spectra automatically. After the continuum normalization is done for the original spectral flux, line detection is made by comparing the normalized flux with the mean and standard deviation of the flux in its neighbor region The results of the experiment on massive spectra from SDSS DR8 indicate that the method can identify ELS spectra completely and accurately. Since no complex transformation and computation are involved in this method, the identifying process is fast and it is ideal for the ELS detection in large sky survey projects like LAMOST and SDSS. PMID:22870668

  1. [A new automated method to identify emission line star from massive spectra].

    PubMed

    Pan, Jing-Chang; Zhang, Cai-Ming; Wei, Peng; Luo, A-Li; Zhao, Yong-Heng

    2012-06-01

    Stellar spectra are characterized by obvious absorption lines or absorption bands, while those with emission lines are usually special stars such as cataclysmic variable stars (CVs), HerbigAe/Be etc. The further study of this kind of spectra is meaningful. The present paper proposed a new method to identify emission line stars (ELS) spectra automatically. After the continuum normalization is done for the original spectral flux, line detection is made by comparing the normalized flux with the mean and standard deviation of the flux in its neighbor region The results of the experiment on massive spectra from SDSS DR8 indicate that the method can identify ELS spectra completely and accurately. Since no complex transformation and computation are involved in this method, the identifying process is fast and it is ideal for the ELS detection in large sky survey projects like LAMOST and SDSS.

  2. Transitional Disks Associated with Intermediate-Mass Stars: Results of the SEEDS YSO Survey

    NASA Technical Reports Server (NTRS)

    Grady, C.; Fukagawa, M.; Maruta, Y.; Ohta, Y.; Wisniewski, J.; Hashimoto, J.; Okamoto, Y.; Momose, M.; Currie, T.; McElwain, M.; Muto, T.; Kotani, T.; Kusakabe, N. B.; Follette, K.; Bonnefoy, M.; Feldt, M.; Sitko, M.; Takami, M.; Karr, J.; Tamura, M.

    2014-01-01

    where only half of the disk is seen in scattered light at H. We will discuss our survey results in terms of spiral arm theory, dust trapping vortices, and systematic differences in the relative scale height of these disks compared to those around Solar-mass stars. For the disks with spiral arms we discuss the planet-hosting potential, and limits on where giant planets can be located. We also discuss the implications for imaging with extreme adaptive optics instruments. Grady is supported under NSF AST 1008440 and through the NASA Origins of Solar Systems program on NNG13PB64P. JPW is supported NSF AST 100314. 0) in marked contrast to protoplanetary disks, transitional disks exhibit wide range of structural features1) arm visibility correlated with relative scale height in disk2) asymmetric and possibly variable shadowing of outer portions some transitional disks3) confirm pre-transitional disk nature of Oph IRS 48, MWC 758, HD 169142, etc.

  3. 'Marginal' BY Draconis stars

    NASA Technical Reports Server (NTRS)

    Bopp, Bernard W.

    1987-01-01

    Spectroscopic observations of 52 dK-dM stars, obtained at 640-665 nm (with spectral resolution 70-90 pm) using CCD detectors on the coude-feed telescope at KPNO since 1982, are reported. Data for four stars found to have diluted absorption or weak emission above continuum at H-alpha are presented in tables and spectra and discussed in detail. These objects (Gliese numbers 256, 425A, 900, and 907.1) are shown to be 'marginal' BY Dra stars, single objects of age 2.5-3 Gyr with activity and rotational velocity (3-5 km/s) between those of normal dM stars and those of true BY Dra stars. An explanation based on evolution from the BY Dra stage through marginal BY Dra to inactive dM is proposed.

  4. Producing Runaway Stars

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-07-01

    How are the hypervelocity stars weve observed in our galaxy produced? A recent study suggests that these escapees could be accelerated by a massive black hole in the center of the Large Magellanic Cloud.A Black Hole SlingshotSince their discovery in 2005, weve observed dozens of candidate hypervelocity stars stars whose velocity in the rest frame of our galaxy exceeds the local escape velocity of the Milky Way. These stars present a huge puzzle: how did they attain these enormous velocities?One potential explanation is known as the Hills mechanism. In this process, a stellar binary is disrupted by a close encounter with a massive black hole (like those thought to reside at the center of every galaxy). One member of the binary is flung out of the system as a result of the close encounter, potentially reaching very large velocities.A star-forming region known as LHA 120-N 11, located within the LMC. Some binary star systems within the LMC might experience close encounters with a possible massive black hole at the LMCs center. [ESA/NASA/Hubble]Blame the LMC?Usually, discussions of the Hills mechanism assume that Sagittarius A*, the supermassive black hole at the center of the Milky Way, is the object guilty of accelerating the hypervelocity stars weve observed. But what if the culprit isnt Sgr A*, but a massive black hole at the center of the Large Magellanic Cloud (LMC), one of the Milky Ways satellite galaxies?Though we dont yet have evidence of a massive black hole at the center of the LMC, the dwarf galaxy is large enough to potentially host one as large as 100,000 solar masses. Assuming that it does, two scientists at the University of Cambridge, Douglas Boubert and Wyn Evans, have now modeled how this black hole might tear apart binary star systems and fling hypervelocity stars around the Milky Way.Models for AccelerationBoubert and Evans determined that the LMCs hypothetical black hole could easily eject stars at ~100 km/s, which is the escape velocity of the

  5. Abundances in Sagittarius Stars

    NASA Astrophysics Data System (ADS)

    Bonifacio, P.; Zaggia, S.; Sbordone, L.; Santin, P.; Monaco, L.; Monai, S.; Molaro, P.; Marconi, G.; Girardi, L.; Ferraro, F.; di Marcantonio, P.; Caffau, E.; Bellazzini, M.

    The Sagittarius dwarf spheroidal is a very complex galaxy, which has undergone prolonged star formation. From the very first high resolution chemical analysis of Sgr stars, conducted using spectra obtained during the commissioning of UVES at VLT, it was clear that the star had undergone a high level of chemical processing, at variance with most of the other Local Group dwarf spheroidals. Thanks to FLAMES at VLT we now have accurate metallicities and abundances of alpha-chain elements for about 150 stars, which provide the first reliable metallicity distribution for this galaxy. Besides the already known high metallicity tail the existence of a metal-poor population has also been highlighted, although an assessment of the fraction of Sgr stars which belong to this population requires a larger sample. From our data it is also obvious that Sagittarius is a nucleated galaxy and that the centre of the nucleus coincides with M54, as already shown by Monaco et al.

  6. Evaluation of the new radiation belt AE9/AP9/SPM model for a cislunar mission

    NASA Astrophysics Data System (ADS)

    Badavi, Francis F.; Walker, Steven A.; Santos Koos, Lindsey M.

    2014-09-01

    this time. From a mission planning point of view, this date is ideal as the predictable GCR exposure will be at a maximum, while the sporadic SEP will be at a minimum. In addition, it is anticipated that by 2020 a vehicle capable of launching a crew of four will be operationally ready. During the LEO-GEO transit, the crew and cargo vehicles will encounter exposure from trapped particles and attenuated GCR, followed by free space exposure due to GCR and SEP during solar active times. Within the trapped field, a challenge arises from properly calculating the amount of exposure acquired. Within this field, in the absence of SEP (i.e. solar quiet times), the vehicles will have to transit through an inner proton belt, an inner and outer electron belts, and an attenuated GCR field. There exist a number of models to define the intensities of the trapped particles during the quiet and active SEP. Among the more established trapped models are the historic and popular electron/proton AE8/AP8 model dating back to the 1980s, the historic and less popular electron/proton CRRES model dating back to 1990s, and the recently released electron/proton/space plasma AE9/AP9/SPM model. The AE9/AP9/SPM model is a major improvement over the older AE8/AP8 and CRRES models. This model is derived from numerous measurements acquired over four solar cycles dating back to the 1970s, roughly representing 40 years of data collection. In contrast, the older AE8/AP8 and CRRES models were limited to only a few months of measurements taken during the prior solar minima and maxima. In this work, within the trapped field, along the design trajectory of the crew vehicle, the AE9/AP9/SPM model is evaluated against the older AE8/AP8 model during solar quiet times. The analysis is then extended to the GCR dominated en-route, cislunar L2 space and return trajectories in order to provide cumulative exposure estimates to the crew vehicle for the duration of the entire mission.

  7. Aerosol absorption coefficient and Equivalent Black Carbon by parallel operation of AE31 and AE33 aethalometers at the Zeppelin station, Ny Ålesund, Svalbard

    NASA Astrophysics Data System (ADS)

    Eleftheriadis, Konstantinos; Kalogridis, Athina-Cerise; Vratolis, Sterios; Fiebig, Markus

    2016-04-01

    Light absorbing carbon in atmospheric aerosol plays a critical role in radiative forcing and climate change. Despite the long term measurements across the Arctic, comparing data obtained by a variety of methods across stations requires caution. A method for extracting the aerosol absorption coefficient from data obtained over the decades by filter based instrument is still under development. An IASOA Aerosol working group has been initiated to address this and other cross-site aerosol comparison opportunities. Continuous ambient measurements of EBC/light attenuation by means of a Magee Sci. AE-31 aethalometer operating at the Zeppelinfjellet station (474 m asl; 78°54'N, 11°53'E), Ny Ålesund, Svalbard, have been available since 2001 (Eleftheriadis et al, 2009), while a new aethalometer model (AE33, Drinovec et al, 2014) has been installed to operate in parallel from the same inlet since June 2015. Measurements are recorded by a Labview routine collecting all available parameters reported by the two instrument via RS232 protocol. Data are reported at 1 and 10 minute intervals as averages for EBC (μg m-3) and aerosol absorption coefficients (Mm-1) by means of routine designed to report Near Real Time NRT data at the EBAS WDCA database (ebas.nilu.no) Results for the first 6 month period are reported here in an attempt to evaluate comparative performance of the two instruments in terms of their response with respect to the variable aerosol load of light absorbing carbon during the warm and cold seasons found in the high arctic. The application of available conversion schemes for obtaining the absorption coefficient by the two instruments is found to demonstrate a marked difference in their output. During clean periods of low aerosol load (EBC < 30 ng m-3), the two instruments display a better agreement with regression slope for the 880 nm signal between the two at ~ 0.9 compared to a slope at ~ 0.6 during the period of higher absorbing carbon loads (400< EBC<30 ng m

  8. Hα Emission Stars and Herbig-Haro Objects in the Vicinity of Bright-rimmed Clouds

    NASA Astrophysics Data System (ADS)

    Ogura, Katsuo; Sugitani, Koji; Pickles, Andrew

    2002-05-01

    Bright-rimmed clouds (BRCs) found in H II regions are probably sites of triggered star formation due to compression by ionization/shock fronts. Many BRCs harbor IRAS point sources of low dust temperature. They also frequently contain a small cluster of near-IR stars that is elongated along the axis of the BRC. Here we present the results of our Hα grism spectroscopy and narrowband imaging observations of BRCs in search of candidate pre-main-sequence stars of the T Tauri, Herbig Ae/Be and related types, and Herbig-Haro (HH) objects. We have detected a large number (460) of Hα emission stars down to a limiting magnitude of about R=20 in and around all but two of the 28 BRCs observed. The present study has, for the first time, reached down nearly to the faintest classical T Tauri star population in OB associations. A total of 12 new HH objects have been found. Most are of small apparent size, emphasizing the need for deep searches at high spatial resolution, but HH 588 associated with BRC 37 represents a huge HH complex composed of two-staged bow shocks on both sides of a tiny central knot. These stars and HH objects are concentrated near the tip of bright rims (i.e., in the head of the BRCs and just outside the rims) and often make loose aggregates similar to those of near-IR stars, thus supporting our hypothesis of ``small-scale sequential star formation.'' The presence of such a large number of Hα emission stars in the immediate vicinities of BRCs implies that second-generation formation of low-mass stars is relatively extensive and further supports the notion of cohabitation of high- and low-mass populations in OB associations.

  9. Infrared Spectro-Interferometry of Massive Stars: Disks, Winds, Outflows, and Stellar Multiplicity

    NASA Astrophysics Data System (ADS)

    Kraus, Stefan

    2007-06-01

    Interferometry is the ultimate technology for overcoming the limitations which diffraction and the atmosphere-induced seeing impose on the resolution achievable with ground-based telescopes. The latest generation of long-baseline interferometric instruments (in particular VLTI/AMBER and VLTI/MIDI), combines the high spatial resolution (typically a few milliarcseconds) with spectroscopic capabilities, allowing one to characterize the geometry of a continuum-emitting region over a wide spectral range or to spatially resolve the emitting region of Doppler-broadened spectral lines in many velocity channels. One branch of astrophysics which might particularly benefit from these advances in technology is the study of massive (O-B type) stars. In order to characterize these stars and their companions and to study accretion and outflow processes in their vicinity with unprecedented angular resolution, we have performed interferometric studies on four key objects, representing the still most enigmatic evolutionary phases of massive stars; namely the pre-main-sequence (MWC 147, NGC 7538 IRS1, Theta 1 Orionis C) and the post-main-sequence phase (Eta Carinae). MWC 147: As indicated by its strong infrared excess, this young Herbig Be star (B6-type) is still associated with residual material from its formation; maybe arranged in a circumstellar disk. In order to investigate the geometry of the material, we combined, for the first time, long-baseline spectro-interferometric observations at near- (NIR) and mid-infrared (MIR) wavelengths (using VLTI/AMBER, VLTI/MIDI, and archival PTI data). Fitting analytic models to the obtained interferometric data revealed a significant elongation of the continuum-emitting region. For a physical interpretation, we modeled the geometry of the dust distribution using 2-D radiative transfer simulations of Keplerian disks with and without a puffed-up inner rim, simultaneously fitting the wavelength-dependent visibilities and the SED, which we

  10. Analysis of high-purity germanium dioxide by ETV-ICP-AES with preliminary concentration of trace elements.

    PubMed

    Medvedev, Nickolay S; Shaverina, Anastasiya V; Tsygankova, Alphiya R; Saprykin, Anatoly I

    2016-08-01

    The paper presents a combined technique of germanium dioxide analysis by inductively coupled plasma atomic emission spectrometry (ICP-AES) with preconcentration of trace elements by distilling off matrix and electrothermal (ETV) introduction of the trace elements concentrate into the ICP. Evaluation of metrological characteristics of the developed technique of high-purity germanium dioxide analysis was performed. The limits of detection (LODs) for 25 trace elements ranged from 0.05 to 20ng/g. The accuracy of proposed technique is confirmed by "added-found" («or spiking») experiment and comparing the results of ETV-ICP-AES and ICP-AES analysis of high purity germanium dioxide samples.

  11. The analysis of chlorine with other elements of interest in waste oil/fuels by ICP-AES

    SciTech Connect

    Tsourides, D.

    1998-12-31

    It has been said that there are more chemical analysis performed on oil/fuels than any other material. The sensitivity, linearity, multi-element capability, and relative freedom from matrix effects of ICP-AES makes it particularly suitable for elemental analysis of these samples. However, until recently the routine analysis of Chlorine had not been possible by ICP-AES. The addition of the Halogen elements, particularly Chlorine, to ICP-AES analysis is of importance to several industries that burn waste oil as fuel. The recycling and disposal of waste oil is closely regulated by metal and halogen content in all developed countries. In some countries, waste oil containing more than 1,000 ppm of Chlorine is considered hazardous waste. However, used oil may be burned as a fuel if it meets certain allowable limits. The paper describes the procedures for chlorine analysis by Inductively Coupled Plasma Atomic Emission Spectroscopy.

  12. Catch a Star!

    NASA Astrophysics Data System (ADS)

    2006-11-01

    ESO and the European Association for Astronomy Education are launching today the 2007 edition of 'Catch a Star!', their international astronomy competition for school students. Now in its fifth year, the competition offers students the chance to win a once-in-a-lifetime trip to ESO's flagship observatory in Chile, as well as many other prizes. Students are invited to 'become astronomers' and embark on a journey to explore the Universe. ESO PR Photo 42/06 The competition includes separate categories - 'Catch a Star Researchers' and 'Catch a Star Adventurers' - to ensure that every student, whatever their level, has the chance to enter and win exciting prizes. For the artistically minded, 'Catch a Star!' also includes an artwork competition, 'Catch a Star Artists'. "'Catch a Star!' offers a unique opportunity for students to learn more about astronomy and about the methods scientists use to discover new things about the Universe", said Douglas Pierce-Price, Education Officer at ESO. In teams, students choose an astronomical topic to study and produce an in-depth report. An important part of the project for 'Catch a Star Researchers' is to think about how ESO's telescopes or a telescope of the future can contribute to their investigations of the subject. As well as the top prize - a trip to one of ESO's observatory sites in Chile - visits to observatories in Germany, Austria and Spain, and many other prizes are also available to be won. 'Catch a Star Researchers' winners will be chosen by an international jury, and 'Catch a Star Adventurers' will be awarded further prizes by lottery. Entries for 'Catch a Star Artists' will be displayed on the web and winners chosen with the help of a public online vote. The first editions of 'Catch a Star!' have attracted several hundred entries from more than 25 countries worldwide. Previous winning entries have included "Star clusters and the structure of the Milky Way" (Budapest, Hungary), "Vega" (Acqui Terme, Italy) and "Venus

  13. PAHs in circumstellar disks around T Tauri stars

    NASA Astrophysics Data System (ADS)

    Geers, Vincent C.; Augereau, Jean-Charles; Pontoppidan, Klaus M.; Dullemond, Cornelis P.; Visser, Ruud; van Dishoeck, Ewine F.; C2d Irs Team

    We have begun to investigate the emission from Polycyclic Aromatic Hydrocarbons seen toward circumstellar disks around young low mass pre-main-sequence (T Tauri) stars, observed as part of our Spitzer Legacy program "From Molecular Cores to Planet-Forming Disks" (Evans et al. 2003). In this poster we will present some of our first Spitzer spectra of PAH features in T Tauri stars and discuss these features in the context of the disk structure and the UV radiation field needed to excite the PAH molecules. Laboratory measurements show that PAH molecules are strongly heated/excited when they absorb a single UV photon, and that they re-radiate the energy through C-H and C-C stretch and C-H bending mode transitions, in the form of infrared photons. These give rise to characteristic PAH features at 3.3, 6.2, 7.7, 8.6, 11.2 and 12.8 microns. These emission features have now been observed toward about 60% of intermediate mass Herbig Ae/Be stars with the ISO satellite (Acke & van den Ancker 2004) and for a few of these sources, ground-based spatially resolved spectroscopy has confirmed that the emission originates from the inner ~100-150 AU region around the star (Geers et al. 2004, van Boekel et al. 2004, Habart et al. 2004), so typically on the scale of circumstellar disks. Our investigation of PAHs in disks around young stars takes two approaches. On the one hand, we address the question how the PAH abundance evolves in these disks during this period of planet formation and how their presence can have an impact on the circumstellar environment. The observed PAH emission is believed to originate from the surface layers of the disk, where the large molecules / small grains are mixed with the gas. The high opacity of PAHs to FUV radiation can significantly reduce the stellar UV field in the inner parts of the disk, while at the same time, through the photo-electric effect, PAHs can provide an important heating mechanism for the gas in the surrounding environment through

  14. Making star teams out of star players.

    PubMed

    Mankins, Michael; Bird, Alan; Root, James

    2013-01-01

    Top talent is an invaluable asset: In highly specialized or creative work, for instance, "A" players are likely to be six times as productive as "B" players. So when your company has a crucial strategic project, why not multiply all that firepower and have a team of your best performers tackle it? Yet many companies hesitate to do this, believing that all-star teams don't work: Big egos will get in the way. The stars won't be able to work with one another. They'll drive the team Leader crazy. Mankins, Bird, and Root of Bain & Company believe it's time to set aside that thinking. They have seen all-star teams do extraordinary work. But there is a right way and a wrong way to organize them. Before you can even begin to assemble such a team, you need to have the right talent management practices, so you hire and develop the best people and know what they're capable of. You have to give the team appropriate incentives and leaders and support staffers who are stars in their own right. And projects that are ill-defined or small scale are not for all-star teams. Use them only for critical missions, and make sure their objectives are clear. Even with the right setup, things can still go wrong. The wise executive will take steps to manage egos, prune non-team-players, and prevent average coworkers from feeling completely undervalued. She will also invest a lot of time in choosing the right team Leader and will ask members for lots of feedback to monitor how that leader is doing. PMID:23390743

  15. RHEED, AES and XPS studies of the passive films formed on ion implanted stainless steel

    SciTech Connect

    Clayton, C.R.; Doss, K.G.K.; Wang, Y.F.; Warren, J.B.; Hubler, G.K.

    1981-12-01

    P-implantation (10/sup 17/ ions cm/sup -2/, 40 KeV) into 304 stainless steel (ss) has been carried out, and an amorphous surface alloy was formed. Polarization studies in deaerated 1N H/sub 2/SO/sub 4/+ 2% NaCl showed that P-implantation improved both the general and localized corrosion resistance of 304 ss. A comparative study has been carried out between the implanted and unimplanted steel to determine what influence P-implantation has upon the properties of the passive film formed 1N H/sub 2/SO/sub 4/. The influence of Cl ions on pre-formed passive films was also studied. RHEED, XPS and AES were used to evaluate the nature of the passive films formed in these studies.

  16. The AE9/AP9/SPM Next Generation Radiation Specification Models - Progress Report

    NASA Astrophysics Data System (ADS)

    O'Brien, Paul; Johnston, William Robert; Huston, Stuart; Guild, Timothy

    2016-07-01

    The AE9/AP9/SPM model has now been released to the global satellite design community, with a recent update to version 1.2. We are working on incorporating new data sources, such as AZUR and NASA's Van Allen Probes, while also addressing critiques raised by the science and engineering communities. In particular, we are investigating discrepancies for protons at low altitude and electrons at geostationary altitudes. Finally, we are scoping out architectural improvements to enable features requested by industry: improved stitching between the plasma and radiation models, local time dependence in the plasma model, longitude dependence in the electron radiation model, and solar cycle variation in the low altitude protons. We provide a brief update on the status of the model, discrepancy investigations, and plans for the future.

  17. VizieR Online Data Catalog: SN 2010ae optical spectra (Stritzinger+, 2014)

    NASA Astrophysics Data System (ADS)

    Stritzinger, M. D.; Hsiao, E.; Valenti, S.; Taddia, F.; Rivera-Thorsen, T. J.; Leloudas, G.; Maeda, K.; Pastorello, A.; Phillips, M. M.; Pignata, G.; Baron, E.; Burns, C. R.; Contreras, C.; Folatelli, G.; Hamuy, M.; Hoeflich, P.; Morrell, N.; Prieto, J. L.; Benetti, S.; Campillay, A.; Haislip, J. B.; Laclutze, A. P.; Moore, J. P.; Reichart, D. E.

    2014-01-01

    With substantial target-of-opportunity (ToO) access on Gemini- South (+GMOS) and the VLT (+X-Shooter), along with visitor nights at the NTT (+EFOSC, SOFI), SOAR (+GOODMAN), and du Pont (+WFCCD) telescopes, a detailed time series of optical and NIR spectroscopy was obtained for SN 2010ae. The resulting early phase time series consists of 21 spectra covering 20 epochs of optical spectroscopy, extending from -2d to +57d relative to T(B)max, as well as eight NIR spectra covering seven epochs ranging from -1d to +18d. Additionally, at late phases a visual-wavelength spectrum was taken with the VLT (+FORS2) on +252d. (2 data files).

  18. ICP-AES Determination of Mineral Content in Boletus tomentipes Collected from Different Sites of China.

    PubMed

    Wang, Xue-mei; Zhang, Ji; Li, Tao; Li, Jie-qing; Wang, Yuan-zhong; Liu, Hong-gao

    2015-05-01

    P, Na, Ca, Cu, Fe, Mg, Zn, As, Cd, Co, Cr and Ni, contents have been examined in caps and stipes of Boletus tomentipes collected from different sites of Yunnan province, southwest China. The elements were determined using inductively coupled plasma atomic emission spectroscopy (ICP-AES) with microwave digestion. P, Ca, Mg, Fe, Zn and Cu were the most abundant amongst elements determined in Boletus tomentipes. The caps were richer in P, Mg, Zn and Cd, and the stipes in Ca, Co and Ni. Cluster analysis showed a difference between Puer (BT7 and BT8) and other places. The PCA explained about 77% of the total variance, and the minerals differentiating these places were P (PC1) together with Ca, Cu, Fe, Mg, As and Ni, Na (PC2) together with Cd, and Zn (PC3). The results of this study imply that element concentrations of a mushroom are mutative when collected from the different bedrock soil geochemistry. PMID:26415467

  19. Asphodosides A-E, anti-MRSA metabolites from Asphodelus microcarpus

    PubMed Central

    Ghoneim, Mohammed M.; Elokely, Khaled M.; El-Hela, Atef A.; Mohammad, Abd-Elsalam I.; Jacob, Melissa; Radwan, Mohamed M.; Doerksen, Robert J.; Cutler, Stephen J.; Ross, Samir A.

    2016-01-01

    Bioassay guided fractionation of the ethanolic extract of Asphodelus microcarpus Salzm. et Viv. (Xanthorrhoeaceae or Asphodelaceae) resulted in isolation of five compounds identified as asphodosides A-E (1–5). Compounds 2–4 showed activity against methicillin resistant Staphylococcus aureus (MRSA) with IC50 values of 1.62, 7.0 and 9.0 μg/mL, respectively. They also exhibited activity against Staphylococcus aureus (non-MRSA) with IC50 values of 1.0, 3.4 and 2.2 μg/mL, respectively. The structure elucidation of isolated metabolites was carried out using spectroscopic data (1D and 2D NMR), optical rotation and both experimental and calculated electronic circular dichroism (ECD). PMID:25034614

  20. ICP-AES Determination of Mineral Content in Boletus tomentipes Collected from Different Sites of China.

    PubMed

    Wang, Xue-mei; Zhang, Ji; Li, Tao; Li, Jie-qing; Wang, Yuan-zhong; Liu, Hong-gao

    2015-05-01

    P, Na, Ca, Cu, Fe, Mg, Zn, As, Cd, Co, Cr and Ni, contents have been examined in caps and stipes of Boletus tomentipes collected from different sites of Yunnan province, southwest China. The elements were determined using inductively coupled plasma atomic emission spectroscopy (ICP-AES) with microwave digestion. P, Ca, Mg, Fe, Zn and Cu were the most abundant amongst elements determined in Boletus tomentipes. The caps were richer in P, Mg, Zn and Cd, and the stipes in Ca, Co and Ni. Cluster analysis showed a difference between Puer (BT7 and BT8) and other places. The PCA explained about 77% of the total variance, and the minerals differentiating these places were P (PC1) together with Ca, Cu, Fe, Mg, As and Ni, Na (PC2) together with Cd, and Zn (PC3). The results of this study imply that element concentrations of a mushroom are mutative when collected from the different bedrock soil geochemistry.

  1. [Determination of harmful elements in various fish tissues by ICP-AES].

    PubMed

    He, Jin-Zhe; Liu, Wen-Han; Yang, Kai; Wu, Hao

    2007-06-01

    Twelve kinds of fish tissues were wetly decomposed and the harmful elements of Cd, As, Pb and Hg were determined by ICP-AES method in the present paper. The techniques for operating ICP instrument were optimized, spectral interference for elements in special wavelength range was studied, and the correction factor of IECs model was established. The results indicated that the signal to noise ratio and detection limit for elements with higher ionization potential energy may be improved by increasing the radio generator power properly and reducing the nebulizer pressure. There were Cr, Cu, As, Sn and Na elements that mainly disturbed the determined elements such as As (189.042 nm), Pb (220.353 nm), Cd (228.802 nm) and Hg (184.950 nm). The primary contaminating elements in tissues of freshwater fish and seawater fish were Pb and As respectively.

  2. Characterization of new and degraded mirrors with AES, ESCA and SIMS

    NASA Astrophysics Data System (ADS)

    Pederson, L. R.; Thomas, M. T.

    1980-09-01

    Samples representing each production stage of second surface mirrors for solar energy concentrators were examined by AES, ESCA, and SIMS along with ion sputtering. Significant weathering occurred on a 6-month-old soda-lime-silicate glass that was intended for use in the Barstow solar pilot plant. Further glass-water reactions occurred during the silvering step, which was demonstrated by the detection of deuterium in the glass on mirrors made from D2O silver solutions. In addition, diffusion of silver into the glass matrix was observed, even on freshly prepared mirrors. On degraded specimens, sulfur was strongly associated with the reacting edge of the copper films, while chloride was similarly associated with the silver films, implying that these elements are important corrosive agents.

  3. [Analysis of rare earth elements in pu'er tea of Yunnan by ICP-AES].

    PubMed

    Ning, Peng-bo; Gong, Chun-mei; Zhang, Yan-ming; Guo, Kang-kang

    2010-10-01

    The 150 samples of pu'er tea collected from the main producing area of Yunnan were detected by ICP-AES method, to investigate the current safety status of pu'er tea rare earth elements. The rare earth elements contents were found to be in the range 0.26-4.07 mg x kg(-1) in all detected samples, with the 43.0% samples exceeding the maximum levels of contaminants of 2 mg x kg(-1) set by GB 2762-2005 "Maximum levels of contaminants in foods". There was a significant difference between ripened tea rare earth elements and raw tea's from the same sources, which affected some ripened tea quality at last. There was a significant difference among the rare earth elements contents of the pu'er tea main producing areas, and the condition of pu'er tea quality and safety controlling was not optimistic at individual producing areas.

  4. New isoprenylated flavones, artochamins A--E, and cytotoxic principles from Artocarpus chama.

    PubMed

    Wang, Yong-Hong; Hou, Ai-Jun; Chen, Lei; Chen, Dao-Feng; Sun, Han-Dong; Zhao, Qin-Shi; Bastow, Kenneth F; Nakanish, Yuka; Wang, Xi-Hong; Lee, Kuo-Hsiung

    2004-05-01

    Five new isoprenylated flavones, artochamins A-E (1-5), together with eight known flavones (6-13), were isolated from the roots of Artocarpus chama. All structures were elucidated by spectroscopic methods. Artonin E (12) showed strong cytotoxicity against 1A9 (ovarian), significant activity against MCF-7 (breast adenocarcinoma), and moderate activity against HCT-8 (ileocecal) and MDA-MB-231 (breast adenocarcinoma) tumor cell lines. Artochamin C (3) was more potent against MCF-7, 1A9, HCT-8, and SK-MEL-2 (melanoma) than A549 (lung carcinoma), KB (epidermoid carcinoma of the nasopharynx), and its drug-resistant (KB-VIN) variant. Artocarpin (6) displayed weak but relatively broad inhibitory effects compared with 3 and 12.

  5. Chondrosterins A-E, triquinane-type sesquiterpenoids from soft coral-associated fungus Chondrostereum sp.

    PubMed

    Li, Hou-Jin; Xie, Ying-Lu; Xie, Zhong-Liang; Chen, Ying; Lam, Chi-Keung; Lan, Wen-Jian

    2012-03-01

    The marine fungus Chondrostereum sp. was collected from a soft coral Sarcophyton tortuosum from the South China Sea. This fungus was cultured in potato dextrose broth medium and the culture broth was extracted with EtOAc. Five new triquinane-type sesquiterpenoids, chondrosterins A-E (1-5), and the known sesquiterpenoid hirsutanol C (6), were isolated. The structures were elucidated mainly on the basis of NMR, MS, and X-ray single-crystal diffraction data. Chondrosterin A (1) showed significant cytotoxic activities against cancer lines A549, CNE2, and LoVo with IC(50) values of 2.45, 4.95, and 5.47 μM, respectively.

  6. Pseudosynchronization of Heartbeat Stars

    NASA Astrophysics Data System (ADS)

    Zimmerman, Mara; Thompson, Susan E.; Hambleton, Kelly; Fuller, Jim; Shporer, Avi; Isaacson, Howard T.; Howard, Andrew; Kurtz, Donald

    2016-01-01

    A type of eccentric binary star that undergoes extreme dynamic tidal forces, known as Heartbeat stars, were discovered by the Kepler Mission. As the two stars pass through periastron, the tidal distortion causes unique brightness variations. Short period, eccentric binary stars, like these, are theorized to pseudosynchronize, or reach a rotational frequency that matches the weighted average orbital angular velocity of the system. This pseudosynchronous rate, as predicted by Hut (1981), depends on the binary's orbital period and eccentricity. We tested whether sixteen heartbeat stars have pseudosynchronized. We measure the rotation rate from obvious spot signatures in the light curve. We measure the eccentricity by fitting the light curve using PHOEBE and are actively carrying out a radial velocity monitoring program with Keck/HIRES in order to improve these orbital parameters. Our initial results show that while most heartbeat stars appear to have pseudosynchronized we find stars with rotation frequencies both longer and shorter than this rate. We thank the SETI Institute REU program, the NSF, and the Kepler Guest Observer Program for making this work possible.

  7. Dense Axion Stars

    NASA Astrophysics Data System (ADS)

    Mohapatra, Abhishek; Braaten, Eric; Zhang, Hong

    2016-03-01

    If the dark matter consists of axions, gravity can cause them to coalesce into axion stars, which are stable gravitationally bound Bose-Einstein condensates of axions. In the previously known axion stars, gravity and the attractive force between pairs of axions are balanced by the kinetic pressure. If the axion mass energy is mc2 =10-4 eV, these dilute axion stars have a maximum mass of about 10-14M⊙ . We point out that there are also dense axion stars in which gravity is balanced by the mean-field pressure of the axion condensate. We study axion stars using the leading term in a systematically improvable approximation to the effective potential of the nonrelativistic effective field theory for axions. Using the Thomas-Fermi approximation in which the kinetic pressure is neglected, we find a sequence of new branches of axion stars in which gravity is balanced by the mean-field interaction energy of the axion condensate. If mc2 =10-4 4 eV, the first branch of these dense axion stars has mass ranging from about 10-11M⊙ toabout M⊙.

  8. Comparison between the polar cap index, PC and the auroral electrojet indices AE, AL, and AU

    SciTech Connect

    Vennerstrom, S.; Friis-Christensen, E. ); Troshichev, O.A.; Andresen, V.G. )

    1991-01-01

    The newly introduced index PC for magnetic activity in the polar cap has been examined to establish to which extent it can serve as an indicator of auroral electrojet activity. PC is derived from a single nearpole station, as a 15-min average index. The authors have derived it for two stations, one in the northern hemisphere (Thule) and one in the southern hemisphere (Vostok). The simplicity of the PC index enables us to make a large data base for statistical investigations. They have thus used 7 years of PC values for the two stations to analyze the relationship between PC and the auroral zone indices AE, AU, and AL statistically. They find a very high correlation between PC and AE during winter and equinox, the linear correlation coefficient being {approximately} 0.8-0.9 for Thule and {approximately} 0.7-0.8 for Vostok. During summer the correlation is less because the PC index is then disturbed by polar cap currents controlled by the northward and east-west components of the interplanetary magnetic field. They therefore stress the importance of having PC available from both the northern and southern hemisphere. From event studies they find that PC is sensitive both to DP 2 type electrojet activity and to substorm intensifications of the westward electrojet in the midnight or postmidnight sector but less sensitive to substorm intensifications of the westward electrojet in the midnight or post midnight sector. They conclude that PC can serve as a fast available indicator of DP 2 and DP 1 activity in the polar regions, excluding intrusions of the westward electrojet in the premidnight sector.

  9. Chandra X-Ray Observatory's Radiation Environment and the AP-8/AE-8 Model

    NASA Technical Reports Server (NTRS)

    Virani, S. N.; Plucinsky, P. P.; Butt, Y. M.; Mueller-Mellin, R.

    2000-01-01

    The Chandra X-ray Observatory (CXO) was launched on July 23, 1999 and reached its final orbit on August 7, 1999. The CXO is in a highly elliptical orbit, approximately 140,000 km x 10,000 km, and has a period of roughly 63.5 hours (approx. 2.6 days). It transits the Earth's Van Allen belts once per orbit during which no science observations can be performed due to the high radiation environment. The Chandra X-ray Observatory Center (CXC) currently uses the National Space Science Data Center's "near Earth" AP-8/AE-8 radiation belt model to predict the start and end times of passage through the radiation belts. However, our scheduling software only uses a simple dipole model of the Earth's magnetic field. The resulting B, L magnet coordinates, do not always give sufficiently accurate predictions of the start and end times of transit of the Van Allen belts. We show this by comparing to the data from Chandra's on-board radiation monitor, the EPHIN (Electron, Proton, Helium Instrument particle detector) instrument. We present evidence that demonstrates this mis- of the radiation belts as well as data that also demonstrate the significant variability of one radiation belt transit to the next as experienced by the CXO. We present an explanation for why the dipole implementation of the AP-8/AE-8 gives inaccurate results. We are also investigating use of the Magnetospheric Specification and Forecast Model (MSM) - a model that also accounts for radiation belt variability and geometry.

  10. Chandra X-ray Observatory's radiation environment and the AP-8/AE-8 model

    NASA Astrophysics Data System (ADS)

    Virani, Shanil N.; Mueller-Mellin, Reinhold; Plucinsky, Paul P.; Butt, Yousaf M.

    2000-07-01

    The Chandra X-ray Observatory (CXO) was launched on July 23, 1999 and reached its final orbit on August 7, 1999. The CXO is in a highly elliptical orbit, approximately 140,000 km X 10,000 km, and has a period of approximately 63.5 hours (approximately equals 2.65 days). It transits the Earth's Van Allen belts once per orbit during which no science observations can be performed due to the high radiation environment. The Chandra X-ray Observatory Center currently uses the National Space Science Data Center's `near Earth' AP-8/AE-8 radiation belt model to predict the start and end times of passage through the radiation belts. However, our scheduling software uses only a simple dipole model of the Earth's magnetic field. The resulting B, L magnetic coordinates, do not always give sufficiently accurate predictions of the start and end times of transit of the Van Allen belts. We show this by comparing to the data from Chandra's on-board radiation monitor, the EPHIN (Electron, Proton, Helium Instrument particle detector) instrument. We present evidence that demonstrates this mis-timing of the outer electron radiation belt as well as data that also demonstrate the significant variability of one radiation belt transit to the next as experienced by the CXO. We also present an explanation for why the dipole implementation of the AP-8/AE-8 model is not ideally suited for the CXO. Lastly, we provide a brief discussion of our on-going efforts to identify a model that accounts for radiation belt variability, geometry, and one that can be used for observation scheduling purposes.

  11. Prescribing the Kp, AE and Dst Response Using the Magnetospheric State Technique

    NASA Astrophysics Data System (ADS)

    Fung, S. F.; Van Artsdalen, K. J.; Shao, X.

    2014-12-01

    The magnetosphere exhibits a variety of geomagnetic activities in response to different solar wind and interplanetary magnetic field (IMF) input. Global-scale geomagnetic activities, such as those due to substorms and storms, are reflected in the Kp, AE and Dst indices, which are constructed from ground-based magnetometer observations. Understanding how and the conditions under which a geomagnetic storm or substorm occurs are outstanding questions in heliophysics and space weather predication. While it is generally accepted that Earth-directed coronal mass ejections from the sun can cause geomagnetic storms and substorms in the magnetosphere, the specific necessary and sufficient conditions, in terms of both the solar wind drivers and pre-existing magnetospheric conditions, for triggering different types of geomagnetic activities are yet to be delineated. For example, while it is generally thought that geomagnetic storms can be triggered by extended intervals of southward IMF Bz, it is still not clear how and at what point during the southward-IMF Bz interval a storm will arise, and how the storm-triggering process may be affected by the pre-existing state of the magnetosphere. To address these specific questions, we have applied the magnetospheric state prescription technique developed by Fung and Shao [2008]. We have used solar wind and geomagnetic indices data taken in 1970-2009 to constructed a magnetospheric state lookup table and applied the table to perform out-of-sample predictions or prescriptions of the Kp, AE and Dst indices during different geomagnetic storm intervals (with minimum Dst ≤ -100 nT) that occurred after 2009. Our presentation will discuss the validity of the magnetospheric state prescription technique and the role of different magnetopsheric state parameters in prescribing geomagnetic storm development. Fung, S. F. and X. Shao, Specification of multiple geomagnetic responses to variable solar wind and IMF input, Ann. Geophys., 26, 639

  12. STARs in the CNS.

    PubMed

    Ehrmann, Ingrid; Fort, Philippe; Elliott, David J

    2016-08-15

    STAR (signal transduction and activation of RNA) proteins regulate splicing of target genes that have roles in neural connectivity, survival and myelination in the vertebrate nervous system. These regulated splicing targets include mRNAs such as the Neurexins (Nrxn), SMN2 (survival of motor neuron) and MAG (myelin-associated glycoprotein). Recent work has made it possible to identify and validate STAR protein splicing targets in vivo by using genetically modified mouse models. In this review, we will discuss the importance of STAR protein splicing targets in the CNS (central nervous system). PMID:27528753

  13. Strange nonchaotic stars.

    PubMed

    Lindner, John F; Kohar, Vivek; Kia, Behnam; Hippke, Michael; Learned, John G; Ditto, William L

    2015-02-01

    The unprecedented light curves of the Kepler space telescope document how the brightness of some stars pulsates at primary and secondary frequencies whose ratios are near the golden mean, the most irrational number. A nonlinear dynamical system driven by an irrational ratio of frequencies generically exhibits a strange but nonchaotic attractor. For Kepler's "golden" stars, we present evidence of the first observation of strange nonchaotic dynamics in nature outside the laboratory. This discovery could aid the classification and detailed modeling of variable stars. PMID:25699444

  14. Mariner 9 star photography.

    NASA Technical Reports Server (NTRS)

    Thorpe, T. E.

    1973-01-01

    Mariner 9 achieved successful photography of the stars, the purpose of the experiment being to measure camera parameters associated with point source photometry, and to examine the feasibility of using stars as invariant calibration sources and a reference for optical navigation. The Mariner 9 camera-B photography demonstrated photometric response consistency over a limited sample of data to better than 15%. Camera performance verified the ability to model vidicon response characteristics as well as demonstrated an imaging capability sufficient to permit the use of stars for photometric calibration.

  15. On the conversion of neutron stars into quark stars

    NASA Astrophysics Data System (ADS)

    Pagliara, Giuseppe

    2014-03-01

    The possible existence of two families of compact stars, neutron stars and quark stars, naturally leads to a scenario in which a conversion process between the two stellar objects occurs with a consequent release of energy of the order of 1053 erg. We discuss recent hydrodynamical simulations of the burning process and neutrino diffusion simulations of cooling of a newly formed strange star. We also briefly discuss this scenario in connection with recent measurements of masses and radii of compact stars.

  16. Mass loss of massive stars

    NASA Astrophysics Data System (ADS)

    Martins, F.

    2015-12-01

    In this contribution we review the properties of the winds of massive stars. We focus on OB stars, red supergiants, Luminous Blue Variables (LBVs) and Wolf-Rayet stars. For each type of star, we summarize the main wind properties and we give a brief description of the physical mechanism(s) responsible for mass loss.

  17. A SAMPLE OF INTERMEDIATE-MASS STAR-FORMING REGIONS: MAKING STARS AT MASS COLUMN DENSITIES <1 g cm{sup -2}

    SciTech Connect

    Arvidsson, K.; Kerton, C. R.; Alexander, M. J.; Kobulnicky, H. A.; Uzpen, B. E-mail: kerton@iastate.ed E-mail: chipk@uwyo.ed E-mail: buzpen@itt-tech.ed

    2010-08-15

    In an effort to understand the factors that govern the transition from low- to high-mass star formation, for the first time we identify a sample of intermediate-mass star-forming regions (IM SFRs) where stars up to (but not exceeding) {approx}8 M{sub sun} are being produced. We use IRAS colors and Spitzer Space Telescope mid-IR images, in conjunction with millimeter continuum and {sup 13}CO maps, to compile a sample of 50 IM SFRs in the inner Galaxy. These are likely to be precursors to Herbig AeBe stars and their associated clusters of low-mass stars. IM SFRs constitute embedded clusters at an early evolutionary stage akin to compact H II regions, but they lack the massive ionizing central star(s). The photodissociation regions that demarcate IM SFRs have typical diameters of {approx}1 pc and luminosities of {approx}10{sup 4} L{sub sun}, making them an order of magnitude less luminous than (ultra-)compact H II regions. IM SFRs coincide with molecular clumps of mass {approx}10{sup 3} M{sub sun} which, in turn, lie within larger molecular clouds spanning the lower end of the giant molecular cloud mass range, 10{sup 4}-10{sup 5} M{sub sun}. The IR luminosity and associated molecular mass of IM SFRs are correlated, consistent with the known luminosity-mass relationship of compact H II regions. Peak mass column densities within IM SFRs are {approx}0.1-0.5 g cm{sup -2}, a factor of several lower than ultra-compact H II regions, supporting the proposition that there is a threshold for massive star formation at {approx}1 g cm{sup -2}.

  18. The origin of stars

    NASA Astrophysics Data System (ADS)

    Smith, Michael D.

    Where do stars come from and how do they form? These are profound questions which link the nature of our Universe to the roots of mankind. Yet, until a recent revolution in understanding, the proposed answers have been raw speculation. Now, accompanying penetrating observations, a new picture has come into prominence. This book presents the latest astounding observations and scientific ideas covering star formation, star birth and early development. It encompasses all aspects, from the dramatic stories of individual objects, to the collective influence of entire stellar systems. The very first stars to come into existence and the nurturing of planets are discussed to provide the reader with a comprehensive overview. Presenting background information with only the essential mathematics, this book will appeal to scientists wishing to expand their horizons, students seeking solid foundations, and general readers with enquiring minds.

  19. Discovery of variable stars

    NASA Technical Reports Server (NTRS)

    Kurochkin, N. Y.

    1973-01-01

    Instrumented methods of discovering variable stars are reviewed, specifically the blink comparator, color contrast method, positive-negative method, and television method. Among the empirical methods discussed, the Van Gent method is the most important.

  20. Planets Around Neutron Stars

    NASA Technical Reports Server (NTRS)

    Wolszczan, Alexander; Kulkarni, Shrinivas R; Anderson, Stuart B.

    2003-01-01

    The objective of this proposal was to continue investigations of neutron star planetary systems in an effort to describe and understand their origin, orbital dynamics, basic physical properties and their relationship to planets around normal stars. This research represents an important element of the process of constraining the physics of planet formation around various types of stars. The research goals of this project included long-term timing measurements of the planets pulsar, PSR B1257+12, to search for more planets around it and to study the dynamics of the whole system, and sensitive searches for millisecond pulsars to detect further examples of old, rapidly spinning neutron stars with planetary systems. The instrumentation used in our project included the 305-m Arecibo antenna with the Penn State Pulsar Machine (PSPM), the 100-m Green Bank Telescope with the Berkeley- Caltech Pulsar Machine (BCPM), and the 100-m Effelsberg and 64-m Parkes telescopes equipped with the observatory supplied backend hardware.