WorldWideScience

Sample records for radio continuum imaging

  1. A Radio Continuum Study of Dwarf Galaxies: 6 cm Imaging of LITTLE THINGS

    Science.gov (United States)

    Hindson, Luke; Kitchener, Ged; Brinks, Elias; Heesen, Volker; Westcott, Jonathan; Hunter, Deidre; Zhang, Hong-Xin; Rupen, Michael; Rau, Urvashi

    2018-02-01

    In this paper, we examine to what extent the radio continuum can be used as an extinction-free probe of star formation in dwarf galaxies. To that aim, we observe 40 nearby dwarf galaxies with the Very Large Array at 6 cm (4–8 GHz) in C-configuration. We obtained images with 3″–8″ resolution and noise levels of 3–15 μJy beam‑1. We detected emission associated with 22 of the 40 dwarf galaxies, eight of which are new detections. The general picture is that of an interstellar medium largely devoid of radio continuum emission, interspersed by isolated pockets of emission associated with star formation. We find an average thermal fraction of ∼50%–70% and an average magnetic field strength of ∼5–8 μG, only slightly lower than that found in larger, spiral galaxies. At 100 pc scales, we find surprisingly high values for the average magnetic field strength of up to 50 μG. We find that dwarf galaxies follow the theoretical predictions of the radio continuum–star formation rate relation within regions of significant radio continuum emission but that the nonthermal radio continuum is suppressed relative to the star formation rate when considering the entire optical disk. We examine the far-infrared–star formation rate relation for our sample and find that the far-infrared is suppressed compared to the expected star formation rate. We discuss explanations for these observed relations and the impact of our findings on the radio continuum–far-infrared relation. We conclude that radio continuum emission at centimeter wavelengths has the promise of being a largely extinction-free star formation rate indicator. We find that star formation rates of gas-rich, low-mass galaxies can be estimated with an uncertainty of ±0.2 dex between the values of 2 × 10‑4 and 0.1 M ⊙ yr‑1.

  2. Cosmological measurements with forthcoming radio continuum surveys

    CSIR Research Space (South Africa)

    Raccanelli, A

    2012-08-01

    Full Text Available We present forecasts for constraints on cosmological models that can be obtained using the forthcoming radio continuum surveys: the wide surveys with the Low Frequency Array (LOFAR) for radio astronomy, theAustralian SquareKilometreArray Pathfinder...

  3. Extragalactic radio continuum surveys and the transformation of radio astronomy

    Science.gov (United States)

    Norris, Ray P.

    2017-10-01

    Next-generation radio surveys are about to transform radio astronomy by discovering and studying tens of millions of previously unknown radio sources. These surveys will provide fresh insights for understanding the evolution of galaxies, measuring the evolution of the cosmic star-formation rate, and rivalling traditional techniques in the measurement of fundamental cosmological parameters. By observing a new volume of observational parameter space, they are also likely to discover unexpected phenomena. This Review traces the evolution of extragalactic radio continuum surveys from the earliest days of radio astronomy to the present, and identifies the challenges that must be overcome to achieve this transformational change.

  4. 20 cm VLA radio-continuum study of M31-images and point source catalogues DR2: Extraction of a supernova remnant sample

    Directory of Open Access Journals (Sweden)

    Galvin T.J.

    2014-01-01

    Full Text Available We present Data Release 2 of the Point Source Catalogue created from a series of previously constructed radio-continuum images of M31 at λ=20 cm (v=1.4 GHz from archived VLA observations. In total, we identify a collection of 916 unique discrete radio sources across the field of M31. Comparing these detected sources to those listed by Gelfand et al. (2004 at λ=92 cm, the spectral index of 98 sources has been derived. The majority (73% of these sources exhibit a spectral index of α<-0.6, indicating that their emission is predominantly non-thermal in nature, which is typical for background objects and Supernova Remnants (SNRs. Additionally, we investigate the presence of radio counterparts for some 156 SNRs and SNR candidates, finding a total of only 13 of these objects in our images within a 500 search area. Auxiliary optical, radio and X-ray catalogues were cross referenced highlighting a small population of SNRs and SNR candidates common to multi frequency domains.

  5. Radio Continuum Surveys with Square Kilometre Array Pathfinders

    Science.gov (United States)

    Norris, Ray P.; Afonso, J.; Bacon, D.; Beck, Rainer; Bell, Martin; Beswick, R. J.; Best, Philip; Bhatnagar, Sanjay; Bonafede, Annalisa; Brunetti, Gianfranco; Budavári, Tamás; Cassano, Rossella; Condon, J. J.; Cress, Catherine; Dabbech, Arwa; Feain, I.; Fender, Rob; Ferrari, Chiara; Gaensler, B. M.; Giovannini, G.; Haverkorn, Marijke; Heald, George; Van der Heyden, Kurt; Hopkins, A. M.; Jarvis, M.; Johnston-Hollitt, Melanie; Kothes, Roland; Van Langevelde, Huib; Lazio, Joseph; Mao, Minnie Y.; Martínez-Sansigre, Alejo; Mary, David; Mcalpine, Kim; Middelberg, E.; Murphy, Eric; Padovani, P.; Paragi, Zsolt; Prandoni, I.; Raccanelli, A.; Rigby, Emma; Roseboom, I. G.; Röttgering, H.; Sabater, Jose; Salvato, Mara; Scaife, Anna M. M.; Schilizzi, Richard; Seymour, N.; Smith, Dan J. B.; Umana, Grazia; Zhao, G.-B.; Zinn, Peter-Christian

    2013-03-01

    In the lead-up to the Square Kilometre Array (SKA) project, several next-generation radio telescopes and upgrades are already being built around the world. These include APERTIF (The Netherlands), ASKAP (Australia), e-MERLIN (UK), VLA (USA), e-EVN (based in Europe), LOFAR (The Netherlands), MeerKAT (South Africa), and the Murchison Widefield Array. Each of these new instruments has different strengths, and coordination of surveys between them can help maximise the science from each of them. A radio continuum survey is being planned on each of them with the primary science objective of understanding the formation and evolution of galaxies over cosmic time, and the cosmological parameters and large-scale structures which drive it. In pursuit of this objective, the different teams are developing a variety of new techniques, and refining existing ones. To achieve these exciting scientific goals, many technical challenges must be addressed by the survey instruments. Given the limited resources of the global radio-astronomical community, it is essential that we pool our skills and knowledge. We do not have sufficient resources to enjoy the luxury of re-inventing wheels. We face significant challenges in calibration, imaging, source extraction and measurement, classification and cross-identification, redshift determination, stacking, and data-intensive research. As these instruments extend the observational parameters, we will face further unexpected challenges in calibration, imaging, and interpretation. If we are to realise the full scientific potential of these expensive instruments, it is essential that we devote enough resources and careful study to understanding the instrumental effects and how they will affect the data. We have established an SKA Radio Continuum Survey working group, whose prime role is to maximise science from these instruments by ensuring we share resources and expertise across the projects. Here we describe these projects, their science goals

  6. Observations of the Solar Continuum Radio Emission at Decameter Wavelengths

    Science.gov (United States)

    Brazhenko, Anatoliy I.; Mel'Nik, Valentin N.; Konovalenko, Alexander A.; Abranin, Edward P.; Dorovskyy, Vladimir V.; Vashchishin, Rostislav V.; Frantzusenko, Anatoly V.; Rucker, Helmut O.

    2010-01-01

    Results of study of the continuum radio emission of the Sun in the decameter range are presented. Observations were carried out with radio telescope URAN-2 in summer months in 2008-2009. Radio fluxes at frequencies 20 MHz and 25 MHz in frequency band 250 kHz were obtained during the time, when there were no active regions on the solar disk. Their average values for two years were 670 Jy and 850 Jy at frequencies 20 MHz and 25 MHz correspondingly. These fluxes are in agreement with high frequency values.

  7. New 6 and 3-cm radio-continuum maps of the Small Magellanic Cloud - part II: Point source catalogue

    Directory of Open Access Journals (Sweden)

    Wong G.F.

    2012-01-01

    Full Text Available We present two new catalogues of radio-continuum sources in the field of the Small Magellanic Cloud (SMC. These catalogues contain sources found at 4800 MHz (λ=6cm and 8640 MHz (λ=3cm. Some 457 sources have been detected at 3cm with 601 sources at 6cm created from new high-sensitivity and resolution radio-continuum images of the SMC from Crawford et al. (2011.

  8. Planck early results. XV. Spectral energy distributions and radio continuum spectra of northern extragalactic radio sources

    DEFF Research Database (Denmark)

    Aatrokoski, J.; Lähteenmäki, A.; Lavonen, N.

    2011-01-01

    Spectral energy distributions (SEDs) and radio continuum spectra are presented for a northern sample of 104 extragalactic radio sources, based on the Planck Early Release Compact Source Catalogue (ERCSC) and simultaneous multifrequency data. The nine Planck frequencies, from 30 to 857 GHz......, are complemented by a set of simultaneous observations ranging from radio to gamma-rays. This is the first extensive frequency coverage in the radio and millimetre domains for an essentially complete sample of extragalactic radio sources, and it shows how the individual shocks, each in their own phase...... of development, shape the radio spectra as they move in the relativistic jet. The SEDs presented in this paper were fitted with second and third degree polynomials to estimate the frequencies of the synchrotron and inverse Compton (IC) peaks, and the spectral indices of low and high frequency radio data...

  9. ARTIP: Automated Radio Telescope Image Processing Pipeline

    Science.gov (United States)

    Sharma, Ravi; Gyanchandani, Dolly; Kulkarni, Sarang; Gupta, Neeraj; Pathak, Vineet; Pande, Arti; Joshi, Unmesh

    2018-02-01

    The Automated Radio Telescope Image Processing Pipeline (ARTIP) automates the entire process of flagging, calibrating, and imaging for radio-interferometric data. ARTIP starts with raw data, i.e. a measurement set and goes through multiple stages, such as flux calibration, bandpass calibration, phase calibration, and imaging to generate continuum and spectral line images. Each stage can also be run independently. The pipeline provides continuous feedback to the user through various messages, charts and logs. It is written using standard python libraries and the CASA package. The pipeline can deal with datasets with multiple spectral windows and also multiple target sources which may have arbitrary combinations of flux/bandpass/phase calibrators.

  10. Radio-continuum observations of a giant radio source QSO J0443.8-6141

    Directory of Open Access Journals (Sweden)

    Filipović M.D.

    2013-01-01

    Full Text Available We report the discovery of a giant double-lobed (lobe-core-lobe radio-continuum structure associated with QSO J0443.8-6141 at z=0.72. This QSO was originally identified during the follow-up of a sample of ROSAT All Sky Survey sources at radio and optical frequencies. With a linear size of ~0.77 Mpc, QSO J0443.8-6141 is classified as a giant radio source (GRS; based on its physical properties, we classify QSO J0443.8-6141 as a FR II radio galaxy. High-resolution observations are required to reliably identify GRSs; the next generation of southern sky radio and optical surveys will be crucial to increasing our sample of these objects.

  11. Planck Early Results. XV. Spectral Energy Distributions and Radio Continuum Spectra of Northern Extragalactic Radio Sources

    Science.gov (United States)

    Aatrokoski, J.; Ade, P. A. R.; Aghanim, N.; Aller, H. D.; Aller, M. F.; Angelakis, E.; Amaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; hide

    2011-01-01

    Spectral energy distributions (SEDs) and radio continuum spectra are presented for a northern sample of 104 extragalactic radio sources. based on the Planck Early Release Compact Source Catalogue (ERCSC) and simultaneous multi frequency data. The nine Planck frequencies, from 30 to 857 GHz, are complemented by a set of simultaneous observations ranging from radio to gamma-rays. This is the first extensive frequency coverage in the radio and millimetre domains for an essentially complete sample of extragalactic radio sources, and it shows how the individual shocks, each in their own phase of development, shape the radio spectra as they move in the relativistic jet. The SEDs presented in this paper were fitted with second and third degree polynomials to estimate the frequencies of the synchrotron and inverse Compton (IC) peaks, and the spectral indices of low and high frequency radio data, including the Planck ERCSC data, were calculated. SED modelling methods are discussed, with an emphasis on proper. physical modelling of the synchrotron bump using multiple components. Planck ERCSC data also suggest that the original accelerated electron energy spectrum could be much harder than commonly thought, with power-law index around 1.5 instead of the canonical 2.5. The implications of this are discussed for the acceleration mechanisms effective in blazar shock. Furthermore in many cases the Planck data indicate that gamma-ray emission must originate in the same shocks that produce the radio emission.

  12. Planck early results. XV. Spectral energy distributions and radio continuum spectra of northern extragalactic radio sources

    Science.gov (United States)

    Planck Collaboration; Aatrokoski, J.; Ade, P. A. R.; Aghanim, N.; Aller, H. D.; Aller, M. F.; Angelakis, E.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Balbi, A.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoît, A.; Berdyugin, A.; Bernard, J.-P.; Bersanelli, M.; Bhatia, R.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Bucher, M.; Burigana, C.; Burrows, D. N.; Cabella, P.; Capalbi, M.; Cappellini, B.; Cardoso, J.-F.; Catalano, A.; Cavazzuti, E.; Cayón, L.; Challinor, A.; Chamballu, A.; Chary, R.-R.; Chiang, L.-Y.; Christensen, P. R.; Clements, D. L.; Colafrancesco, S.; Colombi, S.; Couchot, F.; Coulais, A.; Cutini, S.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Gasperis, G.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Dickinson, C.; Dole, H.; Donzelli, S.; Doré, O.; Dörl, U.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Fuhrmann, L.; Galeotta, S.; Ganga, K.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Giard, M.; Giardino, G.; Giglietto, N.; Giommi, P.; Giordano, F.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Harrison, D.; Henrot-Versillé, S.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hovest, W.; Hoyland, R. J.; Huffenberger, K. M.; Jaffe, A. H.; Juvela, M.; Keihänen, E.; Keskitalo, R.; King, O.; Kisner, T. S.; Kneissl, R.; Knox, L.; Krichbaum, T. P.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Laureijs, R. J.; Lavonen, N.; Lawrence, C. R.; Leach, S.; Leonardi, R.; León-Tavares, J.; Linden-Vørnle, M.; Lindfors, E.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Mann, R.; Maris, M.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Matthai, F.; Max-Moerbeck, W.; Mazziotta, M. N.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Michelson, P. F.; Mingaliev, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Monte, C.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, A.; Naselsky, P.; Natoli, P.; Nestoras, I.; Netterfield, C. B.; Nieppola, E.; Nilsson, K.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; O'Dwyer, I. J.; Osborne, S.; Pajot, F.; Partridge, B.; Pasian, F.; Patanchon, G.; Pavlidou, V.; Pearson, T. J.; Perdereau, O.; Perotto, L.; Perri, M.; Perrotta, F.; Piacentini, F.; Piat, M.; Plaszczynski, S.; Platania, P.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Poutanen, T.; Prézeau, G.; Procopio, P.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Rainò, S.; Reach, W. T.; Readhead, A.; Rebolo, R.; Reeves, R.; Reinecke, M.; Reinthal, R.; Renault, C.; Ricciardi, S.; Richards, J.; Riller, T.; Riquelme, D.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rowan-Robinson, M.; Rubiño-Martín, J. A.; Rusholme, B.; Saarinen, J.; Sandri, M.; Savolainen, P.; Scott, D.; Seiffert, M. D.; Sievers, A.; Sillanpää, A.; Smoot, G. F.; Sotnikova, Y.; Starck, J.-L.; Stevenson, M.; Stivoli, F.; Stolyarov, V.; Sudiwala, R.; Sygnet, J.-F.; Takalo, L.; Tammi, J.; Tauber, J. A.; Terenzi, L.; Thompson, D. J.; Toffolatti, L.; Tomasi, M.; Tornikoski, M.; Torre, J.-P.; Tosti, G.; Tramacere, A.; Tristram, M.; Tuovinen, J.; Türler, M.; Turunen, M.; Umana, G.; Ungerechts, H.; Valenziano, L.; Valtaoja, E.; Varis, J.; Verrecchia, F.; Vielva, P.; Villa, F.; Vittorio, N.; Wandelt, B. D.; Wu, J.; Yvon, D.; Zacchei, A.; Zensus, J. A.; Zhou, X.; Zonca, A.

    2011-12-01

    Spectral energy distributions (SEDs) and radio continuum spectra are presented for a northern sample of 104 extragalactic radio sources, based on the Planck Early Release Compact Source Catalogue (ERCSC) and simultaneous multifrequency data. The nine Planck frequencies, from 30 to 857 GHz, are complemented by a set of simultaneous observations ranging from radio to gamma-rays. This is the first extensive frequency coverage in the radio and millimetre domains for an essentially complete sample of extragalactic radio sources, and it shows how the individual shocks, each in their own phase of development, shape the radio spectra as they move in the relativistic jet. The SEDs presented in this paper were fitted with second and third degree polynomials to estimate the frequencies of the synchrotron and inverse Compton (IC) peaks, and the spectral indices of low and high frequency radio data, including the Planck ERCSC data, were calculated. SED modelling methods are discussed, with an emphasis on proper, physical modelling of the synchrotron bump using multiple components. Planck ERCSC data also suggest that the original accelerated electron energy spectrum could be much harder than commonly thought, with power-law indexaround 1.5 instead of the canonical 2.5. The implications of this are discussed for the acceleration mechanisms effective in blazar shocks. Furthermore in many cases the Planck data indicate that gamma-ray emission must originate in the same shocks that produce the radio emission. Tables 1 and 4, Figs. 18-121 are available in electronic form at http://www.aanda.org

  13. Spatial distribution of far infrared emission in spiral galaxies I. Relation with radio continuum emission

    OpenAIRE

    Y. D. Mayya; Rengarajan, T. N.

    1997-01-01

    We use high resolution IRAS and 20 cm radio continuum (RC) images of a sample of 22 spiral galaxies to study the correlation between the far infra-red (FIR) and RC emissions within the galactic disks. A combination of exponential and gaussian profiles rather than a single exponential profile is found to be a better representation of the observed intensity profiles in the two bands. The gaussian component, which we show is not due to the effects of limited beam-resolution, contains more than 6...

  14. HCO+ and Radio Continuum Emission from the Star Forming Region G75.78+0.34

    Directory of Open Access Journals (Sweden)

    Rogemar A. Riffel

    2014-01-01

    Full Text Available We present 1.3 and 3.6 cm radio continuum images and a HCO+ spectrum of the massive star forming region G75.78+0.34 obtained with the Very Large Array (VLA and with the Berkley Illinois Maryland Association (BIMA interferometer. Three structures were detected in the continuum emission: one associated with the well-known cometary H ɪɪ region, plus two more compact structures located at 6′′ east and at 2′′ south of cometary H ɪɪ region. Using the total flux and intensity peak we estimated an electron density of ≈1.5 × 104 cm−3, an emission measure of ≈6 × 107 cm−6 pc, a mass of ionized gas of ≈3 M⊙, and a diameter of 0.05 pc for the cometary H ɪɪ region, being typical values for an ultracompact H ɪɪ region. The HCO+ emission probably originates from the molecular outflows previously observed in HCN and CO.

  15. The spectral energy distribution of powerful starburst galaxies - I. Modelling the radio continuum

    Science.gov (United States)

    Galvin, T. J.; Seymour, N.; Marvil, J.; Filipović, M. D.; Tothill, N. F. H.; McDermid, R. M.; Hurley-Walker, N.; Hancock, P. J.; Callingham, J. R.; Cook, R. H.; Norris, R. P.; Bell, M. E.; Dwarakanath, K. S.; For, B.; Gaensler, B. M.; Hindson, L.; Johnston-Hollitt, M.; Kapińska, A. D.; Lenc, E.; McKinley, B.; Morgan, J.; Offringa, A. R.; Procopio, P.; Staveley-Smith, L.; Wayth, R. B.; Wu, C.; Zheng, Q.

    2018-02-01

    We have acquired radio-continuum data between 70 MHz and 48 GHz for a sample of 19 southern starburst galaxies at moderate redshifts (0.067 attributed to free-free absorption across multiple regions of star formation with varying optical depths. The decomposed synchrotron and free-free emission components in our sample of galaxies form strong correlations with the total-infrared bolometric luminosities. Finally, we find that without accounting for free-free absorption with turnovers between 90 and 500 MHz the radio continuum at low frequency (ν value of -0.8 for normal galaxies. We suggest this may be caused by an intrinsically steeper cosmic ray distribution.

  16. Spatial distribution of far-infrared emission in spiral galaxies. I. Relation with radio continuum emission.

    Science.gov (United States)

    Mayya, Y. D.; Rengarajan, T. N.

    1997-09-01

    We use high resolution IRAS and 20 cm radio continuum (RC) images of a sample of 22 spiral galaxies to study the correlation between the far infra-red (FIR) and RC emissions within the galactic disks. A combination of exponential and gaussian profiles rather than a single exponential profile is found to be a better representation of the observed intensity profiles in the two bands. The gaussian component, which we show is not due to the effects of limited beam-resolution, contains more than 60% of the total flux in majority of the galaxies. The dominance of the gaussian component suggests that the nuclear star forming regions and the bulge stars are more important contributors to the emission in the two bands, rather than the outer exponential stellar disks. The RC profile is flatter compared to the FIR profile, resulting in a decrease of their ratio, Q-Sixty, away from the center. However, the Q-sixty increases in the extreme outer parts, where the dispersion in the FIR and RC correlation is also higher than in the central regions. The global Q-sixty and its dispersion match those in the inner parts of the galaxies. These results imply that the observed tight correlation in the global quantities reflects processes in the inner regions only where OB stars and the associated Type II supernovae control the FIR and RC emission. In the outer parts heating of very small dust grains by the old disk stars provides a secondary component in the FIR emission, without associated RC emission. The edge-on galaxy NGC3079 shows extended FIR and RC emissions along its minor axis, probably associated with the nuclear starburst activity. keywords - star formation - far infrared emission -- radio continuum emission

  17. Radio-Continuum Jets Around the Peculiar Galaxy Pair ESO 295-IG022

    Directory of Open Access Journals (Sweden)

    Filipovic, M. D.

    2010-12-01

    Full Text Available We report new radio-continuum observations with the Australia Telescope Compact Array (ATCA of the region surrounding the peculiar galaxy pair ESO 295-IG022 at the centre of the poor cluster Abell S0102. We observed this cluster at wavelengths of $lambda$=20/13 and 6/3~cm with the ATCA 6~km array. With these configurations, we achieved a resolution of $sim$2arcsec at 3~cm which is sufficient to resolve the jet-like structure of $sim$3 arcmin lengthdetected at 20~cm. From our new high resolution images at 6 and 3~cm we confirm the presence of a double jet structure, most likely originating from the northern galaxy (ESO 295-IG022-N, bent and twisted towards the south. We found the spectral index of the jet to be very steep ($alpha$=-1.32. No point source was detected that could be associated with the core of ESO 295-IG022-N. On the other hand, ESO 295-IG022-S does not show any jet structure, but does show a point radio source. This source has variable flux and spectral index, and appears to be superposed on the line-of-sight of the jets (seen at 20-cm originating from the northern galaxy ESO 295-IG022-N. Finally, regions of very high and somewhat well ordered polarisation were detected at the level of 70 per cent.

  18. Radio-continuum jets around the peculiar galaxy pair ESO 295-IG022

    Directory of Open Access Journals (Sweden)

    Filipović M.D.

    2010-01-01

    Full Text Available We report new radio-continuum observations with the Australia Telescope Compact Array (ATCA of the region surrounding the peculiar galaxy pair ESO 295-IG022 at the centre of the poor cluster Abell S0102. We observed this cluster at wavelengths of λ=20/13 and 6/3 cm with the ATCA 6 km array. With these configurations, we achieved a resolution of ~2'' at 3 cm which is sufficient to resolve the jet-like structure of ~3' length detected at 20 cm. From our new high resolution images at 6 and 3 cm we confirm the presence of a double jet structure, most likely originating from the northern galaxy (ESO 295-IG022-N, bent and twisted towards the south. We found the spectral index of the jet to be very steep (α=-1.32. No point source was detected that could be associated with the core of ESO 295-IG022-N. On the other hand, ESO 295-IG022-S does not show any jet structure, but does show a point radio source. This source has variable flux and spectral index, and appears to be superposed on the line-of-sight of the jets (seen at 20-cm originating from the northern galaxy ESO 295-IG022-N. Finally, regions of very high and somewhat well ordered polarization were detected at the level of 70%.

  19. Prospects for discovering pulsars in future continuum surveys using variance imaging

    Science.gov (United States)

    Dai, S.; Johnston, S.; Hobbs, G.

    2017-12-01

    In our previous paper, we developed a formalism for computing variance images from standard, interferometric radio images containing time and frequency information. Variance imaging with future radio continuum surveys allows us to identify radio pulsars and serves as a complement to conventional pulsar searches that are most sensitive to strictly periodic signals. Here, we carry out simulations to predict the number of pulsars that we can uncover with variance imaging in future continuum surveys. We show that the Australian SKA Pathfinder (ASKAP) Evolutionary Map of the Universe (EMU) survey can find ∼30 normal pulsars and ∼40 millisecond pulsars (MSPs) over and above the number known today, and similarly an all-sky continuum survey with SKA-MID can discover ∼140 normal pulsars and ∼110 MSPs with this technique. Variance imaging with EMU and SKA-MID will detect pulsars with large duty cycles and is therefore a potential tool for finding MSPs and pulsars in relativistic binary systems. Compared with current pulsar surveys at high Galactic latitudes in the Southern hemisphere, variance imaging with EMU and SKA-MID will be more sensitive, and will enable detection of pulsars with dispersion measures between ∼10 and 100 cm-3 pc.

  20. Astroinformatics Challenges from Next-generation Radio Continuum Surveys

    Science.gov (United States)

    Norris, Ray P.

    2017-06-01

    The tens of millions of radio sources to be detected with next-generation surveys pose new challenges, quite apart from the obvious ones of processing speed and data volumes. For example, existing algorithms are inadequate for source extraction or cross-matching radio and optical/IR sources, and a new generation of algorithms are needed using machine learning and other techniques. The large numbers of sources enable new ways of testing astrophysical models, using a variety of ``large-n astronomy'' techniques such as statistical redshifts. Furthermore, while unexpected discoveries account for some of the most significant discoveries in astronomy, it will be difficult to discover the unexpected in large volumes of data, unless specific software is developed to mine the data for the unexpected.

  1. JVLA 1.5 GHz Continuum Observation of CLASH Clusters. I. Radio Properties of the BCGs

    Science.gov (United States)

    Yu, Heng; Tozzi, Paolo; van Weeren, Reinout; Liuzzo, Elisabetta; Giovannini, Gabriele; Donahue, Megan; Balestra, Italo; Rosati, Piero; Aravena, Manuel

    2018-02-01

    We present high-resolution (∼1″), 1.5 GHz continuum observations of the brightest cluster galaxies (BCGs) of 13 CLASH (Cluster Lensing And Supernova survey with Hubble) clusters at 0.18Radio emission is clearly detected and characterized for 11 BCGs, while for two of them we obtain only upper limits to their radio flux (radio powers in the range from 2× {10}23 to ∼ {10}26 {{W}} {{Hz}}-1 and radio spectral indices {α }1.530 (defined as the slope between 1.5 and 30 GHz) distributed from ∼ -1 to ‑0.25 around the central value =-0.68. The radio emission from the BCGs is resolved in three cases (Abell 383, MACS J1931, and RX J2129), and unresolved or marginally resolved in the remaining eight cases observed with JVLA. In all the cases the BCGs are consistent with being powered by active galactic nuclei. The radio power shows a positive correlation with the BCG star formation rate, and a negative correlation with the central entropy of the surrounding intracluster medium (ICM) except in two cases (MACS J1206 and CL J1226). Finally, over the restricted range in radio power sampled by the CLASH BCGs, we observe a significant scatter between the radio power and the average mechanical power stored in the ICM cavities.

  2. A WARP IN PROGRESS: H I AND RADIO CONTINUUM OBSERVATIONS OF THE SPIRAL NGC 3145

    Energy Technology Data Exchange (ETDEWEB)

    Kaufman, Michele [110 Westchester Rd, Newton, MA 02458 (United States); Brinks, Elias [University of Hertfordshire, Centre for Astrophysics Research, College Lane, Hatfield AL10 9AB (United Kingdom); Struck, Curtis [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Elmegreen, Bruce G. [IBM Research Division, T.J. Watson Research Center, 1101 Kitchawan Rd., Yorktown Heights, NY 10598 (United States); Elmegreen, Debra M., E-mail: kaufmanrallis@icloud.com, E-mail: E.Brinks@herts.ac.uk, E-mail: curt@iastate.edu, E-mail: bge@us.ibm.com, E-mail: elmegreen@vassar.edu [Department of Physics and Astronomy, Vassar College, 124 Raymond Av., Poughkeepsie, NY 12604 (United States)

    2015-09-15

    VLA H i observations and λ6 cm radio continuum observations are presented of the barred-spiral galaxy NGC 3145. In optical images NGC 3145 has stellar arms that appear to cross, forming “X”-features. Our radio continuum observations rule out shock fronts at three of the four “X”-features, and our H i data provide evidence of gas motions perpendicular to the disk of NGC 3145. In large portions of NGC 3145, particularly in the middle-to-outer disk, the H i line profiles are skewed. Relative to the disk, the gas in the skewed wing of the line profiles has z-motions away from us on the approaching side of the galaxy and z-motions of about the same magnitude (∼40 km s{sup −1}) toward us on the receding side. These warping motions imply that there has been a perturbation with a sizeable component perpendicular to the disk over large spatial scales. Two features in NGC 3145 have velocities indicating that they are out-of-plane tidal arms. One is an apparent branch of a main spiral arm on the northeastern side of NGC 3145; the velocity of the branch is ∼150 km s{sup −1} greater than the spiral arm where they appear to intersect in projection. The other is the arm on the southwestern side that forms three of the “X”-features. It differs in velocity by ∼56 km s{sup −1} from that of the disk at the same projected location. H i observations are presented also of the two small companions NGC 3143 and PGC 029578. Based on its properties (enhanced SFR, H i emission 50% more extended on its northeastern side, etc.), NGC 3143 is the more likely of the two companions to have interacted with NGC 3145 recently. A simple analytic model demonstrates that an encounter between NGC 3143 and NGC 3145 is a plausible explanation for the observed warping motions in NGC 3145.

  3. Photometric redshifts for the next generation of deep radio continuum surveys - I. Template fitting

    Science.gov (United States)

    Duncan, Kenneth J.; Brown, Michael J. I.; Williams, Wendy L.; Best, Philip N.; Buat, Veronique; Burgarella, Denis; Jarvis, Matt J.; Małek, Katarzyna; Oliver, S. J.; Röttgering, Huub J. A.; Smith, Daniel J. B.

    2018-01-01

    We present a study of photometric redshift performance for galaxies and active galactic nuclei detected in deep radio continuum surveys. Using two multiwavelength data sets, over the NOAO Deep Wide Field Survey Boötes and COSMOS fields, we assess photometric redshift (photo-z) performance for a sample of ∼4500 radio continuum sources with spectroscopic redshifts relative to those of ∼63 000 non-radio-detected sources in the same fields. We investigate the performance of three photometric redshift template sets as a function of redshift, radio luminosity and infrared/X-ray properties. We find that no single template library is able to provide the best performance across all subsets of the radio-detected population, with variation in the optimum template set both between subsets and between fields. Through a hierarchical Bayesian combination of the photo-z estimates from all three template sets, we are able to produce a consensus photo-z estimate that equals or improves upon the performance of any individual template set.

  4. Radio Continuum and H I Study of Blue Compact Dwarf Galaxies

    Science.gov (United States)

    Ramya, S.; Kantharia, N. G.; Prabhu, T. P.

    2011-02-01

    The multifrequency radio continuum and 21 cm H I observations of five blue compact dwarf (BCD) galaxies, Mrk 104, Mrk 108, Mrk 1039, Mrk 1069, and I Zw 97, using the Giant Meterwave Radio Telescope (GMRT) are presented here. Radio continuum emission at 610 MHz and 325 MHz is detected from all the observed galaxies whereas only a few are detected at 240 MHz. In our sample, three galaxies (Mrk 104, Mrk 108, and Mrk 1039) are members of groups and two galaxies (Mrk 1069 and I Zw 97) are isolated galaxies. The radio emission from Mrk 104 and Mrk 108 is seen to encompass the entire optical galaxy whereas the radio emission from Mrk 1039, Mrk 1069, and I Zw 97 is confined to massive H II regions. This, we suggest, indicates that the star formation in the latter group of galaxies has recently been triggered and that the environment in which the galaxy is evolving plays a role. Star formation rates (SFRs) calculated from 610 MHz emission are in the range 0.01-0.1 M sun yr-1 this is similar to the SFR obtained for individual star-forming regions in BCDs. The integrated radio spectra of four galaxies are modeled over the frequency range where data is available. We find that two of the galaxies, Mrk 1069 and Mrk 1039, show a turnover at low frequencies, which is well fitted by free-free absorption whereas the other two galaxies, Mrk 104 and Mrk 108, show a power law at the lowest GMRT frequencies. The flatter spectrum, localized star formation, and radio continuum in isolated galaxies lend support to stochastic self-propagating star formation. The H I observations of four galaxies, Mrk 104, Mrk 108, Mrk 1039, and Mrk 1069, show extended disks as large as ~1.1-6 times the optical size. All the observed BCDs (except Mrk 104) show rotating disk with a half power width of ~50-124 km s-1. Solid body rotation is common in our sample. We note that the tidal dwarf origin is possible for two of the BCDs in our sample.

  5. VizieR Online Data Catalog: SEDs of the radio continuum from KINGFISHER (Tabatabaei+, 2017)

    Science.gov (United States)

    Tabatabaei, F. S.; Schinnerer, E.; Krause, M.; Dumas, G.; Meidt, S.; Damas-Segovia, A.; Beck, R.; Murphy, E. J.; Mulcahy, D. D.; Groves, B.; Bolatto, A.; Dale, D.; Galametz, M.; Sandstrom, K.; Boquien, M.; Calzetti, D.; Kennicutt, R. C.; Hunt, L. K.; de Looze, I.; Pellegrini, E. W.

    2017-10-01

    The KINGFISH sample consists of 61 nearby galaxies of different morphological types. From this sample, we selected all galaxies with declinations >=-21° and named this subsample KINGFISHER (KINGFISH galaxies Emitting in Radio). These galaxies can be observed with the Effelsberg 100m single-dish telescope to obtain global measurements of the radio continuum at 20cm, 6cm, and 3.6cm. The non-KINGFISH galaxy, M51, is also included in this study. We observed 35 of these galaxies at 6cm, 10 galaxies at 20cm, and 7 at 3.6cm to complete already existing archival data during four observation runs (2008 Dec, 2009 Dec, 2010 Apr and 2010 Dec & 2012 Mar). (3 data files).

  6. Radio peptide imaging and therapy

    Energy Technology Data Exchange (ETDEWEB)

    Buscombe, Jonh [Royal Free Hospital, London (United Kingdom)

    1997-12-31

    Full text. The concept of the magic bullet retains its attraction to us. If only we could take a drug or radioisotope and inject this intravenously and then will attach to the target cancer. This may allow imaging if labelled with a radio pharmaceutical or possibly even effective therapy. Initially work was started using antibodies of mouse origin. These have shown some utility in targeting tumors but there are problems in that these are essentially non-human proteins, often derived from mice. This leads to the formation of antibodies against that antibody so that repeat administrations lead to reduced efficacy and possibly may carry a risk anaphylaxis for the patient. Two different methods have evolved to deal with this situation. Either make antibodies more human or use smaller fragments, so that they are less likely to cause allergic reactions. The second method is to try and use a synthetic peptide. This will contain a series of amino acids which recognize a certain cell receptor. For example the somatostatin analogue Octreotide is an 8 amino acid peptide which has the same biological actions as natural somatostatin but an increased plasma half life. To this is added a linker a good example being DTPA and then radioisotope for example In-111. There we can have the complex In-111-DTPA-Octreotide which can be used to image somatostatin receptors in vivo. The main advantage over antibodies is that the cost production is less and many different variation of peptides for a particular receptor can be manufactured and assessed to find which is the optimal agent tumour imaging at a fraction of the cost of antibody production. There are two main approaches. Firstly to take a natural peptide hormone such as insulin or VIP and label by a simple method such as iodination with I-123. A group in Vienna have done it and shown good uptake of I-123 Insulin in primary hepatomas and of I-123 VIP in pancreatic cancers. Many natural peptide hormones however have a short plasma half

  7. The radio structure of radio-quiet quasars

    NARCIS (Netherlands)

    Leipski, C.; Falcke, H.D.E.; Bennert, N.; Hüttemeister, S.

    2006-01-01

    Aims.We investigate the radio emitting structures of radio-quiet active galactic nuclei with an emphasis on radio-quiet quasars to study their connection to Seyfert galaxies.
    Methods: .We present and analyse high-sensitivity VLA radio continuum images of 14 radio-quiet quasars and six Seyfert

  8. The ZINGRS Radio Survey: Probing metallicities at high-z with far-IR fine-structure lines and the radio continuum

    Science.gov (United States)

    Ferkinhoff, Carl; Higdon, Sarah; Higdon, James L.; Tidwell, Hannah; Rangel, Miguel; Vishwas, Amit; Nikola, Thomas; Stacey, Gordon J.; Brisbin, Drew

    2017-01-01

    The present day Universe is rich in metals that enable efficient cooling of gas in the ISM in order to form stars, create planets and make the building blocks of life as we know it. The Universe did not start in this state - we know that metals had to build up over time with successive generations of stars. Revealing the details of this evolution, however, is challenging and requires probes of metallicity that are not susceptible to dust extinction nor exhibit the degeneracies common to tracers in the visible regime. One possible indicator combines the far-IR fine structure lines with the radio continuum. Recently we have undertaken a multi-band radio continuum survey with the JVLA of high-z galaxies from ZINGRS. These observations will constrain the galaxies’ thermal and nonthermal radio emissions and demonstrate the use of far-IR lines together with radio continuum as a metallicity indicator. ZINGRS, the ZEUS 1 and 2 INvestigated Galaxy Reference Sample, includes ~30 galaxies from z ~ 1 - 4.5 for which the far-IR fine-structure lines (e.g. [CII] 158, [NII] 122, [OIII] 88) have been observed with the ZEUS-1 and 2 instruments. This is the largest collection of far-IR fine-structure line detections at high-z and is ideal for demonstrating the use of this new indicator. Here we describe the theory behind the new indicator, give an overview of ZINGRS, and report on the status of our radio survey.

  9. The radio continuum-star formation rate relation in WSRT sings galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Heesen, Volker; Brinks, Elias [Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Leroy, Adam K. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States); Heald, George [Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo (Netherlands); Braun, Robert [CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia); Bigiel, Frank [Institut für theoretische Astrophysik, Zentrum für Astronomie der Universität Heidelberg, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Beck, Rainer, E-mail: e.brinks@herts.ac.uk, E-mail: v.heesen@soton.ac.uk, E-mail: aleroy@nrao.edu, E-mail: heald@astron.nl, E-mail: Robert.Braun@csiro.au, E-mail: bigiel@uni-heidelberg.de, E-mail: rbeck@mpifr-bonn.mpg.de [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)

    2014-05-01

    We present a study of the spatially resolved radio continuum-star formation rate (RC-SFR) relation using state-of-the-art star formation tracers in a sample of 17 THINGS galaxies. We use SFR surface density (Σ{sub SFR}) maps created by a linear combination of GALEX far-UV (FUV) and Spitzer 24 μm maps. We use RC maps at λλ22 and 18 cm from the WSRT SINGS survey and Hα emission maps to correct for thermal RC emission. We compare azimuthally averaged radial profiles of the RC and FUV/mid-IR (MIR) based Σ{sub SFR} maps and study pixel-by-pixel correlations at fixed linear scales of 1.2 and 0.7 kpc. The ratio of the integrated SFRs from the RC emission to that of the FUV/MIR-based SF tracers is R{sub int}=0.78±0.38, consistent with the relation by Condon. We find a tight correlation between the radial profiles of the radio and FUV/MIR-based Σ{sub SFR} for the entire extent of the disk. The ratio R of the azimuthally averaged radio to FUV/MIR-based Σ{sub SFR} agrees with the integrated ratio and has only quasi-random fluctuations with galactocentric radius that are relatively small (25%). Pixel-by-pixel plots show a tight correlation in log-log diagrams of radio to FUV/MIR-based Σ{sub SFR}, with a typical standard deviation of a factor of two. Averaged over our sample we find (Σ{sub SFR}){sub RC}∝(Σ{sub SFR}){sub hyb}{sup 0.63±0.25}, implying that data points with high Σ{sub SFR} are relatively radio dim, whereas the reverse is true for low Σ{sub SFR}. We interpret this as a result of spectral aging of cosmic-ray electrons (CREs), which are diffusing away from the star formation sites where they are injected into the interstellar medium. This is supported by our finding that the radio spectral index is a second parameter in pixel-by-pixel plots: those data points dominated by young CREs are relatively radio dim, while those dominated by old CREs are slightly more RC bright than what would be expected from a linear extrapolation. We studied the ratio R of

  10. CHANG-ES X: Spatially Resolved Separation of Thermal Contribution from Radio Continuum Emission in Edge-on Galaxies

    Science.gov (United States)

    Vargas, Carlos J.; Mora-Partiarroyo, Silvia Carolina; Schmidt, Philip; Rand, Richard J.; Stein, Yelena; Walterbos, René A. M.; Wang, Q. Daniel; Basu, Aritra; Patterson, Maria; Kepley, Amanda; Beck, Rainer; Irwin, Judith; Heald, George; Li, Jiangtao; Wiegert, Theresa

    2018-02-01

    We analyze the application of star formation rate calibrations using Hα and 22 μm infrared (IR) imaging data in predicting the thermal radio component for a test sample of three edge-on galaxies (NGC 891, NGC 3044, and NGC 4631) in the Continuum Halos in Nearby Galaxies—an EVLA Survey (CHANG-ES). We use a mixture of Hα and 24 μm calibration from Calzetti et al. and a linear 22 μm only calibration from Jarrett et al. on the test sample. We apply these relations on a pixel-to-pixel basis to create thermal prediction maps in the two CHANG-ES bands: L and C band (1.5 GHz and 6.0 GHz, respectively). We analyze the resulting nonthermal spectral index maps, and find a characteristic steepening of the nonthermal spectral index with vertical distance from the disk after application of all methods. We find possible evidence of extinction in the 22 μm data as compared to 70 μm Spitzer Multiband Imaging Photometer imaging in NGC 891. We analyze a larger sample of edge-on and face-on galaxy 25–100 μm flux ratios, and find that the ratios for edge-ons are systematically lower by a factor of 1.36, a result we attribute to excess extinction in the mid-IR in edge-ons. We introduce a new calibration for correcting the Hα luminosity for dust when galaxies are edge-on or very dusty.

  11. Outflow structure within 1000 au of high-mass YSOs. I. First results from a combined study of maser and radio continuum emission

    Science.gov (United States)

    Moscadelli, L.; Sánchez-Monge, Á.; Goddi, C.; Li, J. J.; Sanna, A.; Cesaroni, R.; Pestalozzi, M.; Molinari, S.; Reid, M. J.

    2016-01-01

    Context. In high-mass (≥7 M⊙) star formation (SF) studies, high-angular resolution is crucial for resolving individual protostellar outflows (and possibly accretion disks) from the complex contribution of nearby (high- and low-mass) young stellar objects (YSO). Previous interferometric studies have focused mainly on single objects. Aims: A sensitive survey at high angular resolution is required to investigate outflow processes in a statistically significant sample of high-mass YSOs and on spatial scales relevant to testing theories. Methods: We selected a sample of 40 high-mass YSOs from water masers observed within the BeSSeL Survey. We investigated the 3D velocity and spatial structures of the molecular component of massive outflows at milli-arcsecond angular resolution using multi-epoch Very Long Baseline Array (VLBA) observations of 22 GHz water masers. We also characterize the ionized component of the flows using deep images of the radio continuum emission with resolutions of ~0."2, at 6, 13, and 22 GHz with the Jansky Very Large Array (JVLA). Results: We report the first results obtained for a subset of 11 objects from the sample. The water maser measurements provide us with a very accurate description of the molecular gas kinematics. This in turn enables us to estimate the momentum rate of individual outflows, varying in the range 10-3-100M⊙ yr-1 km s-1, among the highest values reported in the literature. In all the observed objects, the continuum emission at 13 and 22 GHz has a compact structure, with its position coincident with that of the water masers. The 6 GHz continuum consists of either compact components (mostly well aligned with the 13 and/or 22 GHz sources) or extended emission (either highly elongated or approximately spherical), which can be offset by up to a few arcseconds from the water masers. The unresolved continuum emission associated with the water masers likely points to the YSO location. The comparison of the radio continuum

  12. Wide field imaging problems in radio astronomy

    Science.gov (United States)

    Cornwell, T. J.; Golap, K.; Bhatnagar, S.

    2005-03-01

    The new generation of synthesis radio telescopes now being proposed, designed, and constructed face substantial problems in making images over wide fields of view. Such observations are required either to achieve the full sensitivity limit in crowded fields or for surveys. The Square Kilometre Array (SKA Consortium, Tech. Rep., 2004), now being developed by an international consortium of 15 countries, will require advances well beyond the current state of the art. We review the theory of synthesis radio telescopes for large fields of view. We describe a new algorithm, W projection, for correcting the non-coplanar baselines aberration. This algorithm has improved performance over those previously used (typically an order of magnitude in speed). Despite the advent of W projection, the computing hardware required for SKA wide field imaging is estimated to cost up to $500M (2015 dollars). This is about half the target cost of the SKA. Reconfigurable computing is one way in which the costs can be decreased dramatically.

  13. Hubble Space Telescope imaging of compact steep spectrum radio sources

    NARCIS (Netherlands)

    deVries, WH; ODea, CP; Baum, SA; Sparks, WB; Biretta, J; deKoff, S; Golombek, D; Lehnert, MD; Macchetto, F; McCarthy, P; Miley, GK

    We present Hubble Space Telescope WFPC2 images taken through a broad red filter (F702W) of 30 Third Cambridge Catalog compact steep spectrum (CSS) radio sources. We have overlaid radio maps taken from the literature on the optical images to determine the radio-optical alignment and to study detailed

  14. Milliarcsecond Imaging of the Radio Emission from the Quasar with the Most Massive Black Hole at Reionization

    Science.gov (United States)

    Wang, Ran; Momjian, Emmanuel; Carilli, Chris L.; Wu, Xue-Bing; Fan, Xiaohui; Walter, Fabian; Strauss, Michael A.; Wang, Feige; Jiang, Linhua

    2017-02-01

    We report Very Long Baseline Array (VLBA) observations of the 1.5 GHz radio continuum emission of the z = 6.326 quasar SDSS J010013.02+280225.8 (hereafter J0100+2802). J0100+2802 is by far the most optically luminous and is a radio-quiet quasar with the most massive black hole known at z > 6. The VLBA observations have a synthesized beam size of 12.10 mas ×5.36 mas (FWHM), and detected the radio continuum emission from this object with a peak surface brightness of 64.6 ± 9.0 μJy beam-1 and a total flux density of 88 ± 19 μJy. The position of the radio peak is consistent with that from SDSS in the optical and Chandra in the X-ray. The radio source is marginally resolved by the VLBA observations. A 2D Gaussian fit to the image constrains the source size to (7.1 ± 3.5) mas × (3.1 ± 1.7) mas. This corresponds to a physical scale of (40 ± 20) pc × (18 ± 10) pc. We estimate the intrinsic brightness temperature of the VLBA source to be TB = (1.6 ± 1.2) × 107 K. This is significantly higher than the maximum value in normal star-forming galaxies, indicating an active galactic nucleus (AGN) origin for the radio continuum emission. However, it is also significantly lower than the brightness temperatures found in highest-redshift radio-loud quasars. J0100+2802 provides a unique example for studying the radio activity in optically luminous and radio-quiet AGNs in the early universe. Further observations at multiple radio frequencies will accurately measure the spectral index and address the dominant radiation mechanism of the radio emission.

  15. Milliarcsecond Imaging of the Radio Emission from the Quasar with the Most Massive Black Hole at Reionization

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ran; Wu, Xue-Bing; Jiang, Linhua [Kavli Institute of Astronomy and Astrophysics at Peking University, No. 5 Yiheyuan Road, Haidian District, Beijing 100871 (China); Momjian, Emmanuel; Carilli, Chris L. [National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801 (United States); Fan, Xiaohui [Steward Observatory, University of Arizona, 933 N Cherry Avenue, Tucson, AZ 85721 (United States); Walter, Fabian [Max-Planck-Institute for Astronomy, Königsstuhl 17, D-69117 Heidelberg (Germany); Strauss, Michael A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Wang, Feige [Department of Astronomy, School of Physics, Peking University, No. 5 Yiheyuan Road, Haidian District, Beijing 100871 (China)

    2017-02-01

    We report Very Long Baseline Array (VLBA) observations of the 1.5 GHz radio continuum emission of the z = 6.326 quasar SDSS J010013.02+280225.8 (hereafter J0100+2802). J0100+2802 is by far the most optically luminous and is a radio-quiet quasar with the most massive black hole known at z > 6. The VLBA observations have a synthesized beam size of 12.10 mas ×5.36 mas (FWHM), and detected the radio continuum emission from this object with a peak surface brightness of 64.6 ± 9.0 μ Jy beam{sup −1} and a total flux density of 88 ± 19 μ Jy. The position of the radio peak is consistent with that from SDSS in the optical and Chandra in the X-ray. The radio source is marginally resolved by the VLBA observations. A 2D Gaussian fit to the image constrains the source size to (7.1 ± 3.5) mas × (3.1 ± 1.7) mas. This corresponds to a physical scale of (40 ± 20) pc × (18 ± 10) pc. We estimate the intrinsic brightness temperature of the VLBA source to be T {sub B} = (1.6 ± 1.2) × 10{sup 7} K. This is significantly higher than the maximum value in normal star-forming galaxies, indicating an active galactic nucleus (AGN) origin for the radio continuum emission. However, it is also significantly lower than the brightness temperatures found in highest-redshift radio-loud quasars. J0100+2802 provides a unique example for studying the radio activity in optically luminous and radio-quiet AGNs in the early universe. Further observations at multiple radio frequencies will accurately measure the spectral index and address the dominant radiation mechanism of the radio emission.

  16. Radio imaging of core-dominated high redshift quasars

    NARCIS (Netherlands)

    Barthel, PD; Vestergaard, M; Lonsdale, CJ

    VLA imaging at kiloparsec-scale resolution of sixteen core-dominated radio-loud QSOs is presented. Many;objects appear to display variable radio emission and their radio morphologies are significantly smaller than those of steep-spectrum quasars, consistent with these objects being observed at sight

  17. Radio Continuum and Far-infrared Emission from the Galaxies in the ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    and ESO 548-G 036 where the uncertainties are 25% and 30% respectively. 3. The radio and FIR emission from the Eridanus galaxies. A total of 72 Eridanus galaxies are detected in the IRAS survey, out of which 38 galaxies were detected in the NVSS. A total of 7 early type (E + S0s) galaxies are detected in radio, most of ...

  18. A Radio Continuum and H I Study of Optically Selected Blue Compact Dwarf Galaxies: Mrk 1039 and Mrk 0104

    Science.gov (United States)

    Ramya, S.; Kantharia, N. G.; Prabhu, T. P.

    2009-09-01

    We present a GMRT radio continuum and H I study of two Blue Compact Dwarf (BCD) galaxies Mrk 1039 and Mrk 0104. GMRT 610 MHz observations of Mrk 1039 show that the emission is coincident with a bright intense star forming region in the east of the galaxy. The emission at 610 MHz is more extended compared to higher frequencies. The radio spectrum is found to steepen away from the star forming region, suggesting the dominance of the non-thermal component at 610 MHz which maybe due to an older (few 100 Myr old) burst. We detect radio emission at 610 and 240 MHz from Mrk 0104 and estimate a spectral index of -1.14. We find that the emission is more extended at the low GMRT frequencies compared to the 1.4 GHz emission. The galaxy shows extended H I distribution which is about 1.3 times the optical size and contains a mass of 9×10^8 M⊙. We also detect a H I cloud about ˜ 4.5 kpc to the north of the galaxy which does not have any obvious optical counterpart. We speculate that this H I cloud could be involved in triggering the current burst of star formation in Mrk 0104.

  19. Imaging spectroscopy of solar radio burst fine structures.

    Science.gov (United States)

    Kontar, E P; Yu, S; Kuznetsov, A A; Emslie, A G; Alcock, B; Jeffrey, N L S; Melnik, V N; Bian, N H; Subramanian, P

    2017-11-15

    Solar radio observations provide a unique diagnostic of the outer solar atmosphere. However, the inhomogeneous turbulent corona strongly affects the propagation of the emitted radio waves, so decoupling the intrinsic properties of the emitting source from the effects of radio wave propagation has long been a major challenge in solar physics. Here we report quantitative spatial and frequency characterization of solar radio burst fine structures observed with the Low Frequency Array, an instrument with high-time resolution that also permits imaging at scales much shorter than those corresponding to radio wave propagation in the corona. The observations demonstrate that radio wave propagation effects, and not the properties of the intrinsic emission source, dominate the observed spatial characteristics of radio burst images. These results permit more accurate estimates of source brightness temperatures, and open opportunities for quantitative study of the mechanisms that create the turbulent coronal medium through which the emitted radiation propagates.

  20. INVESTIGATING PARTICLE ACCELERATION IN PROTOSTELLAR JETS: THE TRIPLE RADIO CONTINUUM SOURCE IN SERPENS

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Kamenetzky, Adriana; Valotto, Carlos [Instituto de Astronomía Teórica y Experimental, (IATE-UNC), X5000BGR Córdoba (Argentina); Carrasco-González, Carlos; Rodríguez, Luis F. [Instituto de Radioastronomía y Astrofísica (IRyA-UNAM), 58089 Morelia, México (Mexico); Araudo, Anabella [University of Oxford, Astrophysics, Keble Road, Oxford OX1 3RH (United Kingdom); Torrelles, José M. [Institut de Ciències de l’Espai (CSIC-IEEC) and Institut de Ciències del Cosmos (UB-IEEC), Martí i Franquès 1, E-08028 Barcelona (Spain); Anglada, Guillem [Instituto de Astrofísica de Andalucía, CSIC, Camino Bajo de Huétor 50, E-18008 Granada (Spain); Martí, Josep [Dept. de Física, EPS de Jaén, Universidad de Jaén, Campus Las Lagunillas s/n, A3-402, E-23071 Jaén (Spain)

    2016-02-10

    While most protostellar jets present free–free emission at radio wavelengths, synchrotron emission has also been proposed to be present in a handful of these objects. The presence of nonthermal emission has been inferred by negative spectral indices at centimeter wavelengths. In one case (the HH 80-81 jet arising from a massive protostar), its synchrotron nature was confirmed by the detection of linearly polarized radio emission. One of the main consequences of these results is that synchrotron emission implies the presence of relativistic particles among the nonrelativistic material of these jets. Therefore, an acceleration mechanism should be taking place. The most probable scenario is that particles are accelerated when the jets strongly impact against the dense envelope surrounding the protostar. Here we present an analysis of radio observations obtained with the Very Large Array of the triple radio source in the Serpens star-forming region. This object is known to be a radio jet arising from an intermediate-mass protostar. It is also one of the first protostellar jets where the presence of nonthermal emission was proposed. We analyze the dynamics of the jet and the nature of the emission and discuss these issues in the context of the physical parameters of the jet and the particle acceleration phenomenon.

  1. Radio imaging of core-dominated high redshift quasars

    DEFF Research Database (Denmark)

    Barthel, Peter D.; Vestergaard, Marianne; Lonsdale, Colin J.

    1999-01-01

    VLA imaging at kiloparsec-scale resolution of sixteen core-dominated radio-loud QSOs is presented. Many objects appear to display variable radio emission and their radio morphologies are significantly smaller than those of steep-spectrum quasars, consistent with these objects being observed...... at sight lines close to their (relativistic, $\\gamma \\approx$ 4-7) jet axes. The usefulness of the radio source orientation indicator R_V, being defined as ratio of radio core and rest frame optical V-band luminosity, is confirmed....

  2. Radio Continuum and Far-infrared Emission from the Galaxies in the ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... ... a few Myr of the onset of an intense star formation episode after being quiescent for at least a 100 Myr. The upper end of the radio luminosity distribution of the Eridanus galaxies (20cm ∼ 1022W Hz-1) is consistent with that of the field galaxies, other groups, and late-type galaxies in nearby clusters.

  3. Fast radio burst tied to distant dwarf galaxy (Image 2)

    National Science Foundation

    2017-06-07

    Full Text Available Radio telescope at Arecibo only localized the fast radio burst to the area inside the two circles in this image, but the Very Large Array was able to pinpoint it as a dwarf galaxy within the square (shown at intersection of cross hairs in enlarged box)

  4. Emission line imaging of 3CR quasars and radio galaxies

    NARCIS (Netherlands)

    Hes, R; Barthel, PD; Fosbury, RAE

    Optical emission line images and spectra of sixteen 3CR powerful radio galaxies and quasars are presented. Extended line emission is detected in both radio galaxies and quasars. We show that line luminosities, derived from the spatially integrated [OII]lambda 3727 narrow emission line, are on

  5. e-MERLIN Radio Continuum Measurements of OB Star Winds in CYG OB2

    Science.gov (United States)

    Morford, Jack; Prinja, Raman; Fenech, Danielle

    2017-03-01

    Here, we report on the first results from the e-MERLIN Cyg OB2 Radio Survey (COBRaS), which is designed to exploit e-MERLIN's enhanced capabilities to conduct deep-field mapping of the tremendously rich Cyg OB2 association. The project aims to deliver the most detailed radio census of the most massive OB association in the northern hemisphere. There exists considerable evidence for clumping in the winds of hot stars, which has hugely important consequences for mass-loss determinations. The amount of mass lost from a massive star is a crucial parameter required for stellar and cluster evolution models that are paramount to our understanding of the formation and evolution of massive star clusters. Presenting some of the first 20cm (L band) detections of massive stars in Cyg OB2, both accurate mass-loss determinations and constraints upon clumping within their winds are made. These data substantially increase the observational detections of the outer wind of massive stars and in combination with other observations at different wavelengths, COBRaS will greatly advance our knowledge of clumping as a function of radial distance around massive stars.

  6. Evidence for a Multiphase ISM in Early Type Galaxies and Elliptical Galaxies with Strong Radio Continuum

    Science.gov (United States)

    Kim, Dong Woo

    1997-01-01

    We have observed NGC 1316 (Fornax A) with the ROSAT HRI. In this paper, we present the results of these observations and we complement them with the spectral analysis of the archival PSPC data. The spectral properties suggest the presence of a significant component of thermal X-ray emission (greater than 60%), amounting to approx. 10(exp 9) solar mass of hot ISM. Within 3 feet from the nucleus of NGC 1316, the HRI X-ray surface brightness falls as r(exp -2) following the stellar light. In the inner approx. 30 inch., however, the X-ray surface brightness is significantly elongated, contrary to the distribution of stellar light, which is significantly rounder within 10 inch. This again argues for a non-stellar origin of the X-ray emission. This flattened X-ray feature is suggestive of either the disk-like geometry of a rotating cooling flow and/or the presence of extended, elongated dark matter. By comparing the morphology of the X-ray emission with the distribution of optical dust patches, we find that the X-ray emission is significantly reduced at the locations where the dust patches are more pronounced, indicating that at least some of the X-ray photons are absorbed by the cold ISM. We also compare the distribution of the hot and cold ISM with that of the ionized gas, using recently obtained H(sub alpha) CCD data. We find that the ionized gas is distributed roughly along the dust patches and follows the large scale X-ray distribution at r greater than 1 foot from the nucleus. However, there is no one-to-one correspondence between ionized gas and hot gas. Both morphological relations and kinematics suggest different origins for hot and cold ISM. The radio jets in projection appear to pass perpendicularly through the central X-ray ellipsoid. Comparison of thermal and radio pressures suggests that the radio jets are confined by the surrounding hot gaseous medium.

  7. Continuous Shape Estimation of Continuum Robots Using X-ray Images.

    Science.gov (United States)

    Lobaton, Edgar J; Fu, Jinghua; Torres, Luis G; Alterovitz, Ron

    2013-05-06

    We present a new method for continuously and accurately estimating the shape of a continuum robot during a medical procedure using a small number of X-ray projection images (e.g., radiographs or fluoroscopy images). Continuum robots have curvilinear structure, enabling them to maneuver through constrained spaces by bending around obstacles. Accurately estimating the robot's shape continuously over time is crucial for the success of procedures that require avoidance of anatomical obstacles and sensitive tissues. Online shape estimation of a continuum robot is complicated by uncertainty in its kinematic model, movement of the robot during the procedure, noise in X-ray images, and the clinical need to minimize the number of X-ray images acquired. Our new method integrates kinematics models of the robot with data extracted from an optimally selected set of X-ray projection images. Our method represents the shape of the continuum robot over time as a deformable surface which can be described as a linear combination of time and space basis functions. We take advantage of probabilistic priors and numeric optimization to select optimal camera configurations, thus minimizing the expected shape estimation error. We evaluate our method using simulated concentric tube robot procedures and demonstrate that obtaining between 3 and 10 images from viewpoints selected by our method enables online shape estimation with errors significantly lower than using the kinematic model alone or using randomly spaced viewpoints.

  8. An MF/HF radio array for radio and radar imaging of the ionosphere

    Science.gov (United States)

    Isham, Brett; Gustavsson, Bjorn; Belyey, Vasyl; Bullett, Terrence

    2016-07-01

    The Aguadilla Radio Array will be installed at the Interamerican University Aguadilla Campus, located in northwestern Puerto Rico. The array is intended for broad-band medium and high-frequency (MF/HF, roughly 2 to 25 MHz) radio and bistatic radar observations of the ionosphere. The main array consists of 20 antenna elements, arranged in a semi-random pattern providing a good distribution of baseline vectors, with 6-meter minimum spacing to eliminate spacial aliasing. A relocatable 6-element array is also being developed, in which each element consists of a crossed pair of active electric dipoles and all associated electronics for phase-coherent radio measurements. A primary scientific goal of the array is to create images of the region of ionospheric radio emissions stimulated by the new Arecibo Observatory high-power high-frequency radio transmitter. A second primary goal is the study of ionospheric structure and dynamics via coherent radar imaging of the ionosphere in collaboration with the University of Colorado / NOAA Versatile Interferometric Pulsed Ionospheric Radar (VIPIR), located at the USGS San Juan Observatory in Cayey, Puerto Rico. In addition to ionospheric research in collaboration with the Cayey and Arecibo Observatories, the goals of the project include the development of radio sounding, polarization, interferometry, and imaging techniques, and training of students at the university and high school levels.

  9. The radio continuum spectrum of Centaurus A's large-scale components

    Science.gov (United States)

    Alvarez, H.; Aparici, J.; May, J.; Reich, P.

    2000-03-01

    Using our own observations at 45 MHz and data found in the literature after an exhaustive search, we have attempted a comprehensive study of the integrated flux density spectrum of the Centaurus A radio galaxy and of its large scale components. The spectrum for the whole object, between 10 and 4750 MHz, can be well represented by a power law with a spectral index of -0.70+/- 0.01, disproving the existence of a spectral break reported by other authors in the past. Between 406 and 4750 MHz we present, for the first time, the spectra of the individual Giant Outer Lobes and find that, within the errors of measurement, their spectral indices are practically equal. We show that the Giant Outer Lobes contribute with 73% of the total luminosity of the object. That the indices of the different large scale components are close or equal supports the double injection hypothesis for their origin. We discuss the spectral indices and luminosities, and we determine upper bounds for the ages of the radiating electrons. We show that Centaurus A supports the P-alpha rather than the z-alpha correlation.

  10. Line Shape Effects on Intensity Measurements of Solar Features: Brightness Correction to SOHO MDI Continuum Images

    NARCIS (Netherlands)

    Criscuoli, S.; Ermolli, I.; Del Moro, D.; Giorgi, F.; Tritschler, A.; Uitenbroek, H.; Vitas, N.

    2011-01-01

    Continuum intensity observations obtained with theMichelson Doppler Imager (MDI) on board the SOHO mission provide long time series of filtergrams that are ideal for studying the evolution of large-scale phenomena in the solar atmosphere and their dependence on solar activity. These filtergrams,

  11. M 82 - A radio continuum and polarisation study. II. Polarisation and rotation measures

    Science.gov (United States)

    Adebahr, B.; Krause, M.; Klein, U.; Heald, G.; Dettmar, R.-J.

    2017-12-01

    Context. The composition and morphology of the interstellar medium in starburst galaxies has been well investigated, but the magnetic field properties are still uncertain. The nearby starburst galaxy M 82 provides a unique opportunity to investigate the mechanisms leading to the amplification and reduction of turbulent and regular magnetic fields. Aims: An investigation of the magnetic field properties in M 82 will give insight into mechanisms to generate and maintain a magnetic field as well as depolarisation mechanisms. Possible scenarios of the contribution of the magnetic field to the star-formation rate are evaluated. Methods: Archival data from the Very Large Array (VLA) were combined and re-reduced to cover the wavelength regime at λ3 cm and λ6 cm. Complementary data from the Westerbork Synthesis Radio Telescope (WSRT) at λ18 cm and λ22 cm were reduced and analysed using the RM-Synthesis technique. Results: All observations revealed polarised emission in the inner part of the galaxy, while extended polarised emission up to a distance of 2 kpc from the disk was only detected at λ18 cm and λ22 cm. The observations hint at a magnetised bar in the inner part of the galaxy. We calculate the mass inflow rate due to magnetic stress of the bar to 7.1 M⊙ yr-1, which can be a significant contribution to the star-formation rate (SFR) of M 82 of 13 M⊙ yr-1. The halo shows polarised emission, which might be the remnant of a regular disk field. Indications for a helical field in the inner part of the outflow cone are provided. The coherence length of the magnetic field in the centre could be estimated to 50 pc, which is similar to the size of giant molecular clouds. Using polarisation spectra more evidence for a close coupling of the ionised gas and the magnetic field as well as a two-phase magnetic field topology were found. Electron densities in the halo (⟨ ne ⟩ ≈ 0.009 cm-3) are similar to the ones found in the Milky Way. Conclusions: The magnetic field

  12. MASSIVE STAR FORMATION TOWARD G28.87+0.07 (IRAS 18411-0338) INVESTIGATED BY MEANS OF MASER KINEMATICS AND RADIO TO INFRARED CONTINUUM OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Li, J. J.; Xu, Y. [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Moscadelli, L.; Cesaroni, R. [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Furuya, R. S.; Usuda, T. [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Menten, K. M. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany); Pestalozzi, M.; Elia, D.; Schisano, E., E-mail: jjli@pmo.ac.cn [INAF-Istituto Fisica Spazio Interplanetario, Via Fosso del Cavaliere 100, I-00133 Roma (Italy)

    2012-04-10

    We used the Very Long Baseline Array and the European VLBI Network to perform phase-referenced very long baseline interferometry observations of the three most powerful maser transitions associated with the high-mass star-forming region G28.87+0.07: the 22.2 GHz H{sub 2}O, 6.7 GHz CH{sub 3}OH, and 1.665 GHz OH lines. We also performed Very Large Array (VLA) observations of the radio continuum emission at 1.3 and 3.6 cm and Subaru observations of the continuum emission at 24.5 {mu}m. Two centimeter-continuum sources are detected and one of them (named hot molecular core (HMC)) is compact and placed at the center of the observed distribution of H{sub 2}O, CH{sub 3}OH, and OH masers. The bipolar distribution of line-of-sight velocities and the pattern of the proper motions suggest that the water masers are driven by a (proto)stellar jet interacting with the dense circumstellar gas. The same jet could both excite the centimeter-continuum source named HMC (interpreted as free-free emission from shocked gas) and power the molecular outflow observed at larger scales-although one cannot exclude that the free-free continuum is rather originating from a hypercompact H II region. At 24.5 {mu}m, we identify two objects separated along the north-south direction, whose absolute positions agree with those of the two VLA continuum sources. We establish that {approx}90% of the luminosity of the region ({approx}2 Multiplication-Sign 10{sup 5} L{sub Sun }) is coming from the radio source HMC, which confirms the existence of an embedded massive young stellar object exciting the masers and possibly still undergoing heavy accretion from the surrounding envelope.

  13. The Sun Radio Imaging Space Experiment (SunRISE) Mission

    Science.gov (United States)

    Lazio, Joseph; Kasper, Justin; Maksimovic, Milan; Alibay, Farah; Amiri, Nikta; Bastian, Tim; Cohen, Christina; Landi, Enrico; Manchester, Ward; Reinard, Alysha; Schwadron, Nathan; Cecconi, Baptiste; Hallinan, Gregg; Hegedus, Alex; Krupar, Vratislav; Zaslavsky, Arnaud

    2017-04-01

    Radio emission from coronal mass ejections (CMEs) is a direct tracer of particle acceleration in the inner heliosphere and potential magnetic connections from the lower solar corona to the larger heliosphere. Energized electrons excite Langmuir waves, which then convert into intense radio emission at the local plasma frequency, with the most intense acceleration thought to occur within 20 RS. The radio emission from CMEs is quite strong such that only a relatively small number of antennas is required to detect and map it, but many aspects of this particle acceleration and transport remain poorly constrained. Ground-based arrays would be quite capable of tracking the radio emission associated with CMEs, but absorption by the Earth's ionosphere limits the frequency coverage of ground-based arrays (ν ≳ 15 MHz), which in turn limits the range of solar distances over which they can track the radio emission (≲ 3RS). The state-of-the-art for tracking such emission from space is defined by single antennas (Wind/WAVES, Stereo/SWAVES), in which the tracking is accomplished by assuming a frequency-to-density mapping; there has been some success in triangulating the emission between the spacecraft, but considerable uncertainties remain. We describe the Sun Radio Imaging Space Experiment (SunRISE) mission concept: A constellation of small spacecraft in a geostationary graveyard orbit designed to localize and track radio emissions in the inner heliosphere. Each spacecraft would carry a receiving system for observations below 25 MHz, and SunRISE would produce the first images of CMEs more than a few solar radii from the Sun. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  14. A Radio Continuum and Polarization Study of SNR G57.2+0.8 Associated with Magnetar SGR 1935+2154

    Science.gov (United States)

    Kothes, R.; Sun, X.; Gaensler, B.; Reich, W.

    2018-01-01

    We present a radio continuum and linear polarization study of the Galactic supernova remnant (SNR) G57.2+0.8, which may host the recently discovered magnetar SGR 1935+2154. The radio SNR shows the typical radio continuum spectrum of a mature supernova remnant with a spectral index of α =-0.55+/- 0.02 and moderate polarized intensity. Magnetic field vectors indicate a tangential magnetic field, expected for an evolved SNR, in one part of the SNR, and a radial magnetic field in the other. The latter can be explained by an overlapping arc-like feature, perhaps a pulsar wind nebula, emanating from the magnetar. The presence of a pulsar wind nebula is supported by the low average braking index of 1.2, which we extrapolated for the magnetar, and the detection of diffuse X-ray emission around it. We found a distance of 12.5 kpc for the SNR, which identifies G57.2+0.8 as a resident of the Outer spiral arm of the Milky Way. The SNR has a radius of about 20 pc and could be as old as 41,000 yr. The SNR has already entered the radiative or pressure-driven snowplow phase of its evolution. We compare independently determined characteristics like age and distance for both the SNR and the soft gamma repeater SGR 1935+2154, and conclude that they are physically related.

  15. Radio-imaging for quantitative autoradiography in biology

    Energy Technology Data Exchange (ETDEWEB)

    Charon, Y. E-mail: charon@ipno.in2p3.fr; Laniece, P.; Tricoire, H

    1998-11-01

    We present here an overview of new in vitro and ex vivo radio-imaging systems developed to overcome the limitations of films and emulsions currently used in histological autoradiography experiments. The shortcomings of films for quantitative studies are first introduced. Principles and performances of each family of imagers are discussed and illustrated in various biological contexts. Finally, perspectives of development including nonradioactive labeling techniques are briefly presented.

  16. Imaging Interplanetary CMEs at Radio Frequency From Solar Polar Orbit

    Science.gov (United States)

    Wu, Ji; Sun, Weiying; Zheng, Jianhua; Zhang, Cheng; Wang, Chi; Wang, C. B.; Wang, S.

    Coronal mass ejections (CMEs) are violent discharges of plasma and magnetic fields from the Sun's corona. They have come to be recognized as the major driver of physical conditions in the Sun-Earth system. Consequently, the detection of CMEs is important for un-derstanding and ultimately predicting space weather conditions. The Solar Polar Orbit Radio Telescope (SPORT) is a proposed mission to observe the propagation of interplanetary CMEs from solar polar orbit. The main payload (radio telescope) on board SPORT will be an in-terferometric imaging radiometer working at the meter wavelength band, which will follow the propagation of interplanetary CMEs from a distance of a few solar radii to near 1 AU from solar polar orbit. The SPORT spacecraft will also be equipped with a set of optical and in situ measurement instruments such as a EUV solar telescope, a solar wind plasma experiment, a solar wind ion composition instrument, an energetic particle detector, a wave detector, a mag-netometer and an interplanetary radio burst tracker. In this paper, we first describe the current shortage of interplanetary CME observations. Next, the scientific motivation and objectives of SPORT are introduced. We discuss the basic specifications of the main radio telescope of SPORT with reference to the radio emission mechanisms and the radio frequency band to be observed. Finally, we discuss the key technologies of the SPORT mission, including the con-ceptual design of the main telescope, the image retrieval algorithm and the solar polar orbit injection. Other payloads and their respective observation objectives are also briefly discussed. Key words: Interplanetary CMEs; Interferometric imaging; Solar polar orbit; Radiometer.

  17. Astronomers Make First Images With Space Radio Telescope

    Science.gov (United States)

    1997-07-01

    Marking an important new milestone in radio astronomy history, scientists at the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico, have made the first images using a radio telescope antenna in space. The images, more than a million times more detailed than those produced by the human eye, used the new Japanese HALCA satellite, working in conjunction with the National Science Foundation's (NSF) Very Long Baseline Array (VLBA) and Very Large Array (VLA) ground-based radio telescopes. The landmark images are the result of a long-term NRAO effort supported by the National Aeronautics and Space Administration (NASA). "This success means that our ability to make detailed radio images of objects in the universe is no longer limited by the size of the Earth," said NRAO Director Paul Vanden Bout. "Astronomy's vision has just become much sharper." HALCA, launched on Feb. 11 by Japan's Institute of Space and Astronautical Science (ISAS), is the first satellite designed for radio astronomy imaging. It is part of an international collaboration led by ISAS and backed by NRAO; Japan's National Astronomical Observatory; NASA's Jet Propulsion Laboratory (JPL); the Canadian Space Agency; the Australia Telescope National Facility; the European VLBI Network and the Joint Institute for Very Long Baseline Interferometry in Europe. On May 22, HALCA observed a distant active galaxy called PKS 1519-273, while the VLBA and VLA also observed it. Data from the satellite was received by a tracking station at the NRAO facility in Green Bank, West Virginia. Tape-recorded data from the satellite and from the radio telescopes on the ground were sent to NRAO's Array Operations Center (AOC) in Socorro, NM. In Socorro, astronomers and computer scientists used a special-purpose computer to digitally combine the signals from the satellite and the ground telescopes to make them all work together as a single, giant radio telescope. This dedicated machine, the VLBA Correlator, built as

  18. SMC SMP 24: A Newly Radio-Detected Planetary Nebula in the Small Magellanic Cloud

    Directory of Open Access Journals (Sweden)

    Bojicic, I. S.

    2010-12-01

    Full Text Available In this paper we report a new radio-continuum detection of an extragalactic planetary nebula (PN: SMC~SMP~24. We show the radio-continuum image of this PN and present the measured radio data. The newly reduced radio observations are consistent with the multi-wavelength data and derived parameters found in the literature. SMC~SMP~24 appears to be a young and compact PN, optically thick at frequencies below 2~GHz.

  19. SMC SMP 24: A newly radio-detected planetary nebula in the small Magellanic cloud

    Directory of Open Access Journals (Sweden)

    Bojičić I.S.

    2010-01-01

    Full Text Available In this paper we report a new radio-continuum detection of an extragalactic planetary nebula (PN: SMC SMP 24. We show the radio-continuum image of this PN and present the measured radio data. The newly reduced radio observations are consistent with the multi-wavelength data and derived parameters found in the literature. SMC SMP 24 appears to be a young and compact PN, optically thick at frequencies below 2 GHz.

  20. Dirichlet Methods for Bayesian Source Detection in Radio Astronomy Images

    Science.gov (United States)

    Friedlander, A. M.

    2014-02-01

    The sheer volume of data to be produced by the next generation of radio telescopes - exabytes of data on hundreds of millions of objects - makes automated methods for the detection of astronomical objects ("sources") essential. Of particular importance are low surface brightness objects, which are not well found by current automated methods. This thesis explores Bayesian methods for source detection that use Dirichlet or multinomial models for pixel intensity distributions in discretised radio astronomy images. A novel image discretisation method that incorporates uncertainty about how the image should be discretised is developed. Latent Dirichlet allocation - a method originally developed for inferring latent topics in document collections - is used to estimate source and background distributions in radio astronomy images. A new Dirichlet-multinomial ratio, indicating how well a region conforms to a well-specified model of background versus a loosely-specified model of foreground, is derived. Finally, latent Dirichlet allocation and the Dirichlet-multinomial ratio are combined for source detection in astronomical images. The methods developed in this thesis perform source detection well in comparison to two widely-used source detection packages and, importantly, find dim sources not well found by other algorithms.

  1. Robust sparse image reconstruction of radio interferometric observations with PURIFY

    Science.gov (United States)

    Pratley, Luke; McEwen, Jason D.; d'Avezac, Mayeul; Carrillo, Rafael E.; Onose, Alexandru; Wiaux, Yves

    2018-01-01

    Next-generation radio interferometers, such as the Square Kilometre Array, will revolutionize our understanding of the Universe through their unprecedented sensitivity and resolution. However, to realize these goals significant challenges in image and data processing need to be overcome. The standard methods in radio interferometry for reconstructing images, such as CLEAN, have served the community well over the last few decades and have survived largely because they are pragmatic. However, they produce reconstructed interferometric images that are limited in quality and scalability for big data. In this work, we apply and evaluate alternative interferometric reconstruction methods that make use of state-of-the-art sparse image reconstruction algorithms motivated by compressive sensing, which have been implemented in the PURIFY software package. In particular, we implement and apply the proximal alternating direction method of multipliers algorithm presented in a recent article. First, we assess the impact of the interpolation kernel used to perform gridding and degridding on sparse image reconstruction. We find that the Kaiser-Bessel interpolation kernel performs as well as prolate spheroidal wave functions while providing a computational saving and an analytic form. Secondly, we apply PURIFY to real interferometric observations from the Very Large Array and the Australia Telescope Compact Array and find that images recovered by PURIFY are of higher quality than those recovered by CLEAN. Thirdly, we discuss how PURIFY reconstructions exhibit additional advantages over those recovered by CLEAN. The latest version of PURIFY, with developments presented in this work, is made publicly available.

  2. A solar type II radio burst from CME-coronal ray interaction: simultaneous radio and EUV imaging

    CERN Document Server

    Chen, Yao; Feng, Li; Feng, Shiwei; Kong, Xiangliang; Guo, Fan; Wang, Bing; Li, Gang

    2014-01-01

    Simultaneous radio and extreme ultraviolet (EUV)/white-light imaging data are examined for a solar type II radio burst occurring on 2010 March 18 to deduce its source location. Using a bow-shock model, we reconstruct the 3-dimensional EUV wave front (presumably the type-II emitting shock) based on the imaging data of the two STEREO spacecraft. It is then combined with the Nan\\c{c}ay radio imaging data to infer the 3-dimensional position of the type II source. It is found that the type II source coincides with the interface between the CME EUV wave front and a nearby coronal ray structure, providing evidence that the type II emission is physically related to the CME-ray interaction. This result, consistent with those of previous studies, is based on simultaneous radio and EUV imaging data for the first time.

  3. Interferometric coherence measurement and radio frequency noise characterization of the 1.3 μm femtosecond intense Stokes continuum from a TZDW source

    Science.gov (United States)

    Yao, Yuhong; Knox, Wayne H.

    2015-02-01

    Photonic crystal fiber (PCF) with two closely spaced zero dispersion wavelengths (TZDW) offers a unique route to efficient energy transfer to two spectrally localized continua beyond either side of the ZDWs, which we have employed in previous work for mid-IR difference frequency generation and speckle-free red-green-blue generation. In this manuscript, we report the interferometric coherence characterization and radio frequency (RF) noise measurements of the Stokes side TZDW component. With a custom-built 1.3 W, 1035 nm, 40 MHz, 240 fs Yb:fiber chirped pulse amplifier as the pump source, we use 12 cm of commercially available TZDW PCF to excite the dual narrow-band continua from which the Stokes pulse is filtered out with a 1180 nm long wave pass filter. We achieve 0.8 to 3 nJ of narrow-band pulses within the spectral range of 1200 - 1315 nm at an average power conversion efficiency of 33%. Employing an un-balanced Michelson interferometer, measured mutual spectral coherence of the Stokes pulse is in excess of 0.76 with pump Soliton order as high as N ~70. Its measured RF noise spectrum at the first harmonic of the laser repetition rate shows less than 8 dBc/Hz increase in relative intensity noise (RIN) compared to that of the power amplifier, which is consistent with reported studies employing sub-100 fs pulses from relatively low noise oscillators. In contrast to the broadband continuum from a single ZDW PCF wherein severe de-coherence is found with pumping at high soliton order and longer pump pulse width, the reported TZDW fiber source shows preservation of intensity stability and phase coherence against variation in pump pulse parameters, which not only attests to the stability of our reported method for mid-IR generation, but also shows promising potential towards an all-fiber, efficient and low noise ultrafast source that can be helpful for applications such as biomedical deep-tissue imaging.

  4. The NOD3 software package: A graphical user interface-supported reduction package for single-dish radio continuum and polarisation observations

    Science.gov (United States)

    Müller, Peter; Krause, Marita; Beck, Rainer; Schmidt, Philip

    2017-10-01

    Context. The venerable NOD2 data reduction software package for single-dish radio continuum observations, which was developed for use at the 100-m Effelsberg radio telescope, has been successfully applied over many decades. Modern computing facilities, however, call for a new design. Aims: We aim to develop an interactive software tool with a graphical user interface for the reduction of single-dish radio continuum maps. We make a special effort to reduce the distortions along the scanning direction (scanning effects) by combining maps scanned in orthogonal directions or dual- or multiple-horn observations that need to be processed in a restoration procedure. The package should also process polarisation data and offer the possibility to include special tasks written by the individual user. Methods: Based on the ideas of the NOD2 package we developed NOD3, which includes all necessary tasks from the raw maps to the final maps in total intensity and linear polarisation. Furthermore, plot routines and several methods for map analysis are available. The NOD3 package is written in Python, which allows the extension of the package via additional tasks. The required data format for the input maps is FITS. Results: The NOD3 package is a sophisticated tool to process and analyse maps from single-dish observations that are affected by scanning effects from clouds, receiver instabilities, or radio-frequency interference. The "basket-weaving" tool combines orthogonally scanned maps into a final map that is almost free of scanning effects. The new restoration tool for dual-beam observations reduces the noise by a factor of about two compared to the NOD2 version. Combining single-dish with interferometer data in the map plane ensures the full recovery of the total flux density. Conclusions: This software package is available under the open source license GPL for free use at other single-dish radio telescopes of the astronomical community. The NOD3 package is designed to be

  5. What are “X-shaped” Radio Sources Telling Us? I. Very Large Array Imaging of a Large Sample of Candidate XRGs

    Science.gov (United States)

    Roberts, David H.; Saripalli, Lakshmi; Wang, Kevin X.; Sathyanarayana Rao, Mayuri; Subrahmanyan, Ravi; KleinStern, Carly C.; Morii-Sciolla, Christopher Y.; Simpson, Liana

    2018-01-01

    We present archival and Jansky Very Large Array multi-frequency multi-array radio continuum imaging of a unique sample of 100 radio sources that have been selected to be candidate “X-shaped” radio galaxies (XRGs). The archival data were calibrated in AIPS and imaged using DIFMAP, while the new Very Large Array data were calibrated and imaged in CASA. No attempt was made to re-image the archival data in CASA. Altogether we present images of 95 of the 100 sources. These observations give us the opportunity to study radio sources with synchrotron plasma that is significantly offset from the main radio axis and therefore to open a window into investigations of physical mechanisms responsible for depositing the plasma in off-axis regions. Here, we present the technical details of the observations and all of the total intensity images, while in subsequent papers we use them to examine critically various models for the formation of XRGs. Spectral index and linear polarization information is also presented and analyzed in further papers in this series.

  6. A review of radio interferometric imaging of comets

    Science.gov (United States)

    De Pater, Imke; Palmer, Patrick; Snyder, Lewis E.

    1991-01-01

    An overview of cometary observations carried out with the VLA which include OH imaging observations, studies of other molecules, and searches for continuum emission, is presented. Attention is focussed on the OH observations obtained of Comet Halley, a periodic comet, and Comet Wilson, a 'new' comet. The emission from Comet Halley is confined to a region a few times 10 exp 5 km. The emission from Comet Wilson exhibits sporadic blobs at large distances (about 10 exp 6 from the center), which vary abruptly in both position and velocity. It is suggested that for Comet Halley, collisional effects near the edge of the quenching region, which is coincidentally the approximate distance to the cometopause, may be important, and that for Comet Wilson, outgassing from cometesimals ejected from the nucleus may be significant. It is shown that asymmetric line profiles are more common than previously thought. H2CO detection experiments for comets Halley and Machholz are summarized.

  7. LOFAR tied-array imaging of Type III solar radio bursts

    NARCIS (Netherlands)

    Morosan, D.E.; et al., [Unknown; Hessels, J.W.T.; Markoff, S.

    2014-01-01

    Context. The Sun is an active source of radio emission which is often associated with energetic phenomena such as solar flares and coronal mass ejections (CMEs). At low radio frequencies (<100 MHz), the Sun has not been imaged extensively because of the instrumental limitations of previous radio

  8. LOFAR tied-array imaging of Type III solar radio bursts

    NARCIS (Netherlands)

    Morosan, D.E.; Gallagher, P.T.; Zucca, P.; Fallows, R.; Carley, E.P.; Mann, G.; Bisi, M.M.; Kerdraon, A.; Avruch, I.M.; Bentum, Marinus Jan; Bernardi, G.; Best, P.; Bonafede, A.; Bregman, J.; Breitling, F.

    2014-01-01

    Context: The Sun is an active source of radio emission which is often associated with energetic phenomena such as solar flares and coronal mass ejections (CMEs). At low radio frequencies (<100 MHz), the Sun has not been imaged extensively because of the instrumental limitations of previous radio

  9. A high-resolution radio image of a young supernova

    Energy Technology Data Exchange (ETDEWEB)

    Bartel, N.; Rupen, M.P.; Shapiro, I.I. (Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (USA)); Preston, R.A. (Jet Propulsion Lab., Pasadena, CA (USA)); Rius, A. (Universidad Complutense de Madrid (Spain). Inst. de Astronomia y Geodesia)

    1991-03-21

    Supernovae in our own Galaxy are so rare that images of their remnants can show only the late aftermath of an explosion that occurred anything from a few hundred to several tens of thousands of years ago. Young supernovae are seen frequently in other galaxies, but because they are more distant it has not been possible until now to obtain high-resolution images that would reveal details of the explosion and the immediate development of the ejected material. Here we present a very-long-baseline interferometric (VLBI) radio image of the bright supernova 1986J, which occurred in the galaxy NGC891 at a distance of {similar to}12 Mpc. No detailed image of any supernova or remnant has been obtained before so soon after the explosion. Our image shows a shell of emission with jet-like protrusions. Their analysis should advance our understanding of the dynamics of the expanding debris, the dissipation of energy into the surrounding circumstellar medium, and the evolution of the supernova into the remnant. (author).

  10. Imaging of SNR IC443 and W44 with the Sardinia Radio Telescope at 1.5 and 7 GHz

    Science.gov (United States)

    Egron, E.; Pellizzoni, A.; Iacolina, M. N.; Loru, S.; Marongiu, M.; Righini, S.; Cardillo, M.; Giuliani, A.; Mulas, S.; Murtas, G.; Simeone, D.; Concu, R.; Melis, A.; Trois, A.; Pilia, M.; Navarrini, A.; Vacca, V.; Ricci, R.; Serra, G.; Bachetti, M.; Buttu, M.; Perrodin, D.; Buffa, F.; Deiana, G. L.; Gaudiomonte, F.; Fara, A.; Ladu, A.; Loi, F.; Marongiu, P.; Migoni, C.; Pisanu, T.; Poppi, S.; Saba, A.; Urru, E.; Valente, G.; Vargiu, G. P.

    2017-09-01

    Observations of supernova remnants (SNRs) are a powerful tool for investigating the later stages of stellar evolution, the properties of the ambient interstellar medium and the physics of particle acceleration and shocks. For a fraction of SNRs, multiwavelength coverage from radio to ultra-high energies has been provided, constraining their contributions to the production of Galactic cosmic rays. Although radio emission is the most common identifier of SNRs and a prime probe for refining models, high-resolution images at frequencies above 5 GHz are surprisingly lacking, even for bright and well-known SNRs such as IC443 and W44. In the frameworks of the Astronomical Validation and Early Science Program with the 64-m single-dish Sardinia Radio Telescope, we provided, for the first time, single-dish deep imaging at 7 GHz of the IC443 and W44 complexes coupled with spatially resolved spectra in the 1.5-7 GHz frequency range. Our images were obtained through on-the-fly mapping techniques, providing antenna beam oversampling and resulting in accurate continuum flux density measurements. The integrated flux densities associated with IC443 are S1.5 GHz = 134 ± 4 Jy and S7 GHz = 67 ± 3 Jy. For W44, we measured total flux densities of S1.5 GHz = 214 ± 6 Jy and S7 GHz = 94 ± 4 Jy. Spectral index maps provide evidence of a wide physical parameter scatter among different SNR regions: a flat spectrum is observed from the brightest SNR regions at the shock, while steeper spectral indices (up to ˜ 0.7) are observed in fainter cooling regions, disentangling in this way different populations and spectra of radio/gamma-ray-emitting electrons in these SNRs.

  11. An Image Restoration Method Using Matrix Transform and Gaussian Mixture Model for Radio Tomographic Imaging

    Directory of Open Access Journals (Sweden)

    Fei Gao

    2017-01-01

    Full Text Available Radio Tomographic Imaging (RTI is an attractive technique for imaging the nonmetallic targets within wireless sensor network. RTI has been used in many challenging environments and situations. Due to the accuracy of Radio Tomographic Imaging system model and the interference between the wireless signals of sensors, the image obtained from the RTI system is a degraded target image, which cannot offer sufficient details to distinguish different targets. In this paper, we treat the RTI system as an image degraded process, and we propose an estimation model based on mixture Gaussian distribution to derive the degradation function from the shadowing-based RTI model. Then we use this degradation function to recover an original image by a method called constrained least squares filtering. So far, many imaging models have been proposed for localization; however, they do not have a satisfied imaging accuracy. Simulated and experimental results show that the imaging accuracy of our proposed method is improved, and the proposed method can be used in the real-time circumstances.

  12. Multi-GPU maximum entropy image synthesis for radio astronomy

    Science.gov (United States)

    Cárcamo, M.; Román, P. E.; Casassus, S.; Moral, V.; Rannou, F. R.

    2018-01-01

    The maximum entropy method (MEM) is a well known deconvolution technique in radio-interferometry. This method solves a non-linear optimization problem with an entropy regularization term. Other heuristics such as CLEAN are faster but highly user dependent. Nevertheless, MEM has the following advantages: it is unsupervised, it has a statistical basis, it has a better resolution and better image quality under certain conditions. This work presents a high performance GPU version of non-gridding MEM, which is tested using real and simulated data. We propose a single-GPU and a multi-GPU implementation for single and multi-spectral data, respectively. We also make use of the Peer-to-Peer and Unified Virtual Addressing features of newer GPUs which allows to exploit transparently and efficiently multiple GPUs. Several ALMA data sets are used to demonstrate the effectiveness in imaging and to evaluate GPU performance. The results show that a speedup from 1000 to 5000 times faster than a sequential version can be achieved, depending on data and image size. This allows to reconstruct the HD142527 CO(6-5) short baseline data set in 2.1 min, instead of 2.5 days that takes a sequential version on CPU.

  13. New CO and Millimeter Continuum Observations of the z = 2.394 Radio Galaxy 53W002.

    Science.gov (United States)

    Alloin; Barvainis; Guilloteau

    2000-01-10

    The z=2.39 radio galaxy 53W002 lies in a cluster of Lyalpha emission-line objects and may itself be undergoing a major burst of star formation. CO (3-2) emission, at 102 GHz, was detected from 53W002 in 1997 by Scoville et al., who also reported a possible 30 kpc extension and velocity gradient suggesting a rotating gaseous disk. In this Letter, we present new interferometric CO (3-2) observations that confirm the previous line detection with improved signal-to-noise ratio, but show no evidence for source extension or velocity gradient. The compact nature of the CO source and the molecular mass found in this object are similar to luminous infrared galaxies and other active galactic nuclei previously studied.

  14. Tracking Galaxy Evolution Through Low-Frequency Radio Continuum Observations using SKA and Citizen-Science Research using Multi-Wavelength Data

    Science.gov (United States)

    Hota, Ananda; Konar, C.; Stalin, C. S.; Vaddi, Sravani; Mohanty, Pradeepta K.; Dabhade, Pratik; Dharmik Bhoga, Sai Arun; Rajoria, Megha; Sethi, Sagar

    2016-12-01

    We present a brief review of progress in the understanding of general spiral and elliptical galaxies, through merger, star formation and AGN activities. With reference to case studies performed with the GMRT, we highlight the unique aspects of studying galaxies in the radio wavelengths where powerful quasars and bright radio galaxies are traditionally the dominating subjects. Though AGN or quasar activity is extremely energetic, it is extremely short-lived. This justify focussing on transitional galaxies to find relic-evidences of the immediate past AGN-feedback which decide the future course of evolution of a galaxy. Relic radio lobes can be best detected in low frequency observations with the GMRT, LOFAR and in future SKA. The age of these relic radio plasma can be as old as a few hundred Myr. There is a huge gap between this and what is found in optical bands. The very first relic-evidences of a past quasar activity (Hanny's Voorwerp) was discovered in 2007 by a Galaxy Zoo citizen-scientist, a school teacher, in the optical bands. This relic is around a few tens of thousand years old. More discoveries needed to match these time-scales with star formation time-scales in AGN host galaxies to better understand black hole galaxy co-evolution process via feedback-driven quenching of star formation. It is now well-accepted that discovery and characterization of such faint fuzzy relic features can be more efficiently done by human eye than a machine. Radio interferometry images are more complicated than optical and need the citizen-scientists to be trained. RAD@home, the only Indian citizen-science research project in astronomy, analysing TIFR GMRT Sky Survey (TGSS) 150 MHz data and observing from the Giant Meterwave Radio Telescope (GMRT), was launched in April 2013. Unique, zero-infrastructure zero-funded design of RAD@home as a collaboratory of 69 trained e-astronomers is briefly described. Some of the new-found objects like episodic radio galaxies, radio-jet and

  15. Radio-tomographic images of postmidnight equatorial plasma depletions

    Science.gov (United States)

    Hei, Matthew A.; Bernhardt, Paul A.; Siefring, Carl L.; Wilkens, Matthew R.; Huba, Joseph D.; Krall, Jonathan F.; Valladares, Cesar E.; Heelis, Roderick A.; Hairston, Marc R.; Coley, W. Robin; Chau, Jorge L.; De La Jara, Cesar

    2014-01-01

    the first time, equatorial plasma depletions (EPDs) have been imaged in the longitude-altitude plane using radiotomography. High-resolution (~10 km) reconstructions of electron density were derived from total electron content (TEC) measurements provided by a receiver array in Peru. TEC data were obtained from VHF/UHF signals transmitted by the Coherent Electromagnetic Radio Tomography (CERTO) beacon on the C/NOFS satellite. EPDs generated premidnight were observed near dawn. On one night, the bubble densities were highly reduced, 100-1000 km wide, and embedded within a layerlike ionosphere. Three nights later, the EPDs exhibited similar features but were embedded in a locally uplifted ionosphere. The C/NOFS in situ instruments detected a dawn depletion where the reconstruction showed lifted EPDs, implying that the postmidnight electric fields raised sections of ionosphere to altitudes where embedded/reactivated fossil EPDs were detected as dawn depletions. Satellites flying under domelike distortions of the ionosphere may observe these distortions as broad plasma decreases (BPDs).

  16. Narrowband Lyman-continuum imaging of galaxies at z ∼ 2.85

    Energy Technology Data Exchange (ETDEWEB)

    Mostardi, R. E.; Shapley, A. E.; Nestor, D. B. [Department of Physics and Astronomy, University of California, Los Angeles, 430 Portola Plaza, Los Angeles, CA 90095 (United States); Steidel, C. C.; Trainor, R. F. [Cahill Center for Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Reddy, N. A. [Department of Physics and Astronomy, University of California, Riverside, 900 University Avenue, Riverside, CA 92521 (United States)

    2013-12-10

    We present results from a survey for z ∼ 2.85 Lyman-continuum (LyC) emission in the HS1549+1933 field and place constraints on the amount of ionizing radiation escaping from star-forming galaxies. Using a custom narrowband filter (NB3420) tuned to wavelengths just below the Lyman limit at z ≥ 2.82, we probe the LyC spectral region of 49 Lyman break galaxies (LBGs) and 91 Lyα emitters (LAEs) spectroscopically confirmed at z ≥ 2.82. Four LBGs and seven LAEs are detected in NB3420. Using V-band data probing the rest-frame nonionizing UV, we observe that many NB3420-detected galaxies exhibit spatial offsets between their LyC and nonionizing UV emission and are characterized by extremely blue NB3420–V colors, corresponding to low ratios of nonionizing to ionizing radiation (F {sub UV}/F {sub LyC}) that are in tension with current stellar population synthesis models. We measure average values of (F {sub UV}/F {sub LyC}) for our LBG and LAE samples, correcting for foreground galaxy contamination and H I absorption in the intergalactic medium. We find (F{sub UV}/F{sub LyC}){sub corr}{sup LBG}=82±45 and (F{sub UV}/F{sub LyC}){sub corr}{sup LAE}=7.4±3.6. These flux density ratios correspond, respectively, to relative LyC escape fractions of f{sub esc,} {sub rel}{sup LBG}=5%--8% and f{sub esc,} {sub rel}{sup LAE}=18%--49%, absolute LyC escape fractions of f{sub esc}{sup LBG}=1%--2% and f{sub esc}{sup LAE}=5%--15%, and a comoving LyC emissivity from star-forming galaxies of 8.8-15.0 × 10{sup 24} erg s{sup –1} Hz{sup –1} Mpc{sup –3}. In order to study the differential properties of galaxies with and without LyC detections, we analyze narrowband Lyα imaging and rest-frame near-infrared imaging, finding that while LAEs with LyC detections have lower Lyα equivalent widths on average, there is no substantial difference in the rest-frame near-infrared colors of LBGs or LAEs with and without LyC detections. These preliminary results are consistent with an

  17. JUICE/RPWI/JENRAGE: a low frequency radio imager at Jupiter

    Science.gov (United States)

    Cecconi, B.; Kasaba, Y.; Bergman, J. E. S.; Zarka, P.; Lamy, L.; Hess, S. L. G.; Rothkaehl, H.

    2015-10-01

    The JENRAGE (Jovian Environment Radio Astronomy and Ganymede Exploration) experiment of the Radio and Plasma Waves Instrument (RPWI) on-board JUICE (Jupiter Icy Moon Explorer) is a sensitive, and versatile radio instrument. It will observe radio waves ranging from 80 kHz to 45 MHz at a 100 Msample per second aquisition rate. The instrument is composed of set of 3 electrical dipoles (developed by the Polish team), connected to low noise preamplifiers and conditioning analog filters (built by the Japanese team), then sampled and digitally filtererd into ~300 kHz bands (digital part developed by the Swedish team). This international project is coordinated by B. Cecconi and Y. Kasaba, both co-PI of JUICE/RPWI. Although the radio antenna connected to this instrument have no intrinsic directivity, the JENRAGE measurements can provide instantaneous direction of arrival, flux density and polarization degree of the observed radio waves. Hence, the JENRAGE can be described as an full-sky radio imager. As the instrument provides direction of arrival, radio sources can be located with some assumption on the propagation between the source and the observer. Hence, it is possible to produce radio source maps and correlate them with observations at other wavelengths, such as UV or IR observations of the auroral regions of Jupiter. The flux and polarization measurements together with the time- frequency shape of the radio emissions can also be used to identify the radio emission processes. These features have shown their capabilities on Cassini, with the RPWS/HFR instrument. We will present the JUICE/RPWI/JENRAGE design and the science objectives. Additional science topics linked to the icy satellites, which are currently being assessed, will also be presented.

  18. Clinical Applications of a CT Window Blending Algorithm: RADIO (Relative Attenuation-Dependent Image Overlay).

    Science.gov (United States)

    Mandell, Jacob C; Khurana, Bharti; Folio, Les R; Hyun, Hyewon; Smith, Stacy E; Dunne, Ruth M; Andriole, Katherine P

    2017-06-01

    A methodology is described using Adobe Photoshop and Adobe Extendscript to process DICOM images with a Relative Attenuation-Dependent Image Overlay (RADIO) algorithm to visualize the full dynamic range of CT in one view, without requiring a change in window and level settings. The potential clinical uses for such an algorithm are described in a pictorial overview, including applications in emergency radiology, oncologic imaging, and nuclear medicine and molecular imaging.

  19. Radio Imaging of a Type IVM Radio Burst on the 14th of August 2010

    Science.gov (United States)

    Bain, H. M.; Krucker, S.; Saint-Hilaire, P.; Raftery, C. L.

    2014-02-01

    Propagating coronal mass ejections (CMEs) are often accompanied by burst signatures in radio spectrogram data. We present Nançay Radioheliograph observations of a moving source of broadband radio emission, commonly referred to as a type IV radio burst (type IVM), which occurred in association with a CME on the 14th of August 2010. The event was well observed at extreme ultraviolet (EUV) wavelengths by SDO/AIA and PROBA2/SWAP, and by the STEREO SECCHI and SOHO LASCO white light (WL) coronagraphs. The EUV and WL observations show the type IVM source to be cospatial with the CME core. The observed spectra is well fitted by a power law with a negative slope, which is consistent with optically thin gyrosynchrotron emission. The spectrum shows no turn over at the lowest Nançay frequencies. By comparing simulated gyrosynchrotron spectra with Nançay Radioheliograph observations, and performing a rigorous parameter search we are able to constrain several key parameters of the underlying plasma. Simulated spectra found to fit the data suggest a nonthermal electron distribution with a low energy cutoff of several tens to 100 keV, with a nonthermal electron density in the range 100-102 cm-3, in a magnetic field of a few Gauss. The nonthermal energy content of the source is found to contain 0.001%-0.1% of the sources thermal energy content. Furthermore, the energy loss timescale for this distribution equates to several hours, suggesting that the electrons could be accelerated during the CME initiation or early propagation phase and become trapped in the magnetic structure of the CME core without the need to be replenished.

  20. Internet Resources for Radio Astronomy

    Science.gov (United States)

    Andernach, H.

    A subjective overview of Internet resources for radio-astronomical information is presented. Basic observing techniques and their implications for the interpretation of publicly available radio data are described, followed by a discussion of existing radio surveys, their level of optical identification, and nomenclature of radio sources. Various collections of source catalogues and databases for integrated radio source parameters are reviewed and compared, as well as the web interfaces to interrogate the current and ongoing large-area surveys. Links to radio observatories with archives of raw (uv-) data are presented, as well as services providing images, both of individual objects or extracts (``cutouts'') from large-scale surveys. While the emphasis is on radio continuum data, a brief list of sites providing spectral line data, and atomic or molecular information is included. The major radio telescopes and surveys under construction or planning are outlined. A summary is given of a search for previously unknown optically bright radio sources, as performed by the students as an exercise, using Internet resources only. Over 200 different links are mentioned and were verified, but despite the attempt to make this report up-to-date, it can only provide a snapshot of the situation as of mid-1998.

  1. GTC optical imaging of extremely red 5C radio galaxies at high redshift

    Science.gov (United States)

    Humphrey, A.; Villar-Martín, M.; Lagos, P.

    2016-01-01

    Aims: We investigate the nature of seven unusual radio galaxies from the 5C catalogue that were previously known to have extremely red R-K colours, and for which emission lines were previously found to be weak or absent in their optical spectra. Methods: We present and discuss u, g, or r images of these radio galaxies, obtained using the Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS) at the Gran Telescopio Canarias (GTC). Results: We have detected all seven targets in our g-band imaging. Their optical emission is extended, and we tentatively detect a radio-optical alignment effect in this sample. A subset of our sample (three sources) shows broad-band spectral energy distributions that flatten out near the wavelength range of the g-band, implying a dominant contribution there due to young stars and/or scattered or reprocessed radiation from the active nucleus.

  2. Predicting consideration of cosmetic surgery in a college population: a continuum of body image disturbance and the importance of coping strategies.

    Science.gov (United States)

    Callaghan, Glenn M; Lopez, Albertina; Wong, Lily; Northcross, Jasalynne; Anderson, Kristina R

    2011-06-01

    Elective cosmetic surgeries are increasing in the American population with reasons linked to body image disturbance and body dysmorphic disorder (BDD). Little research exists documenting the continuum of body image disturbance and its relationship to seeking surgery. The present research examined data from 544 participants, 55 of whom were diagnosable with BDD. Using assessments for body image disturbance, problematic coping strategies, and BDD symptomatology, results provided evidence for a continuum of body image distress. Logistic regression analysis supported the hypothesis that increased levels of body image disturbance and one type of problematic coping strategy (Appearance Fixing) predicted consideration of cosmetic surgery. Of participants diagnosable with BDD, those who considered cosmetic surgery showed more severe body image disturbance and problematic coping than those who did not consider surgery. These results have implications for pre-surgical assessment as well as psychological interventions rather than invasive medical interventions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. The HDUV Survey: Six Lyman Continuum Emitter Candidates at z ˜ 2 Revealed by HST UV Imaging

    Science.gov (United States)

    Naidu, R. P.; Oesch, P. A.; Reddy, N.; Holden, B.; Steidel, C. C.; Montes, M.; Atek, H.; Bouwens, R. J.; Carollo, C. M.; Cibinel, A.; Illingworth, G. D.; Labbé, I.; Magee, D.; Morselli, L.; Nelson, E. J.; van Dokkum, P. G.; Wilkins, S.

    2017-09-01

    We present six galaxies at z˜ 2 that show evidence of Lyman continuum (LyC) emission based on the newly acquired UV imaging of the Hubble Deep UV legacy survey (HDUV) conducted with the WFC3/UVIS camera on the Hubble Space Telescope (HST). At the redshift of these sources, the HDUV F275W images partially probe the ionizing continuum. By exploiting the HST multiwavelength data available in the HDUV/GOODS fields, models of the UV spectral energy distributions, and detailed Monte Carlo simulations of the intergalactic medium absorption, we estimate the absolute ionizing photon escape fractions of these galaxies to be very high—typically > 60 % (> 13 % for all sources at 90% likelihood). Our findings are in broad agreement with previous studies that found only a small fraction of galaxies with high escape fraction. These six galaxies compose the largest sample yet of LyC leaking candidates at z˜ 2 whose inferred LyC flux has been observed at HST resolution. While three of our six candidates show evidence of hosting an active galactic nucleus, two of these are heavily obscured and their LyC emission appears to originate from star-forming regions rather than the central nucleus. Extensive multiwavelength data in the GOODS fields, especially the near-IR grism spectra from the 3D-HST survey, enable us to study the candidates in detail and tentatively test some recently proposed indirect methods to probe LyC leakage. High-resolution spectroscopic follow-up of our candidates will help constrain such indirect methods, which are our only hope of studying f esc at z˜ 5-9 in the JWST era. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  4. Detailed Radio Imaging of a CME with the Murchison Widefield Array

    Science.gov (United States)

    Kozarev, Kamen; Oberoi, Divya; Morgan, John; Crowley, Meagan; Benkevitch, Leonid; Lonsdale, Colin; McCauley, Patrick; Winter, Henry; Cairns, Iver

    2017-04-01

    Solar radio observations allow us to constrain the dynamics of high energy electron beams accelerated in both flares and coronal mass ejections (CME). In particular, the synchrotron emission from erupting flux ropes should give important information about the distributions of energetic electrons trapped in the cores of CMEs. The Murchison Widefield Array is one of several new radio interferometric instruments, and is particularly well-suited to imaging the Sun and solar transients at multiple frequency channels between 80 and 300 MHz. This instrument holds great promise for improving the status of direct CME imaging in the radio. Here we present imaging observations with high frequency and time resolution of a CME, which occurred on November 4, 2015. The observations allow us to obtain detailed frequency spectra of the plasma and synchrotron emission. In addition, such observations may provide independent information about the thermal electron density, as well as the magnetic field strength in the CME flux rope. Finally, these observations provide information about the detailed evolution and kinematics of the CME and its flux rope in its early stages. The new observations demonstrate the capability of the MWA to contribute to the monitoring and detailed analysis of solar eruptions through its high sensitivity, high dynamic range radio imaging.

  5. Application safety evaluation of the radio frequency identification tag under magnetic resonance imaging

    OpenAIRE

    Fei, Xiaolu; Li,Shanshan; Gao, Shan; Wei, Lan; Wang, Lihong

    2014-01-01

    Background Radio Frequency Identification(RFID) has been widely used in healthcare facilities, but it has been paid little attention whether RFID applications are safe enough under healthcare environment. The purpose of this study is to assess the effects of RFID tags on Magnetic Resonance (MR) imaging in a typical electromagnetic environment in hospitals, and to evaluate the safety of their applications. Methods A Magphan phantom was used to simulate the imaging objects, while active RFID ta...

  6. GPU-Based High-performance Imaging for Mingantu Spectral RadioHeliograph

    Science.gov (United States)

    Mei, Ying; Wang, Feng; Wang, Wei; Chen, Linjie; Liu, Yingbo; Deng, Hui; Dai, Wei; Liu, Cuiyin; Yan, Yihua

    2018-01-01

    As a dedicated solar radio interferometer, the MingantU SpEctral RadioHeliograph (MUSER) generates massive observational data in the frequency range of 400 MHz-15 GHz. High-performance imaging forms a significantly important aspect of MUSER’s massive data processing requirements. In this study, we implement a practical high-performance imaging pipeline for MUSER data processing. At first, the specifications of the MUSER are introduced and its imaging requirements are analyzed. Referring to the most commonly used radio astronomy software such as CASA and MIRIAD, we then implement a high-performance imaging pipeline based on the Graphics Processing Unit technology with respect to the current operational status of the MUSER. A series of critical algorithms and their pseudo codes, i.e., detection of the solar disk and sky brightness, automatic centering of the solar disk and estimation of the number of iterations for clean algorithms, are proposed in detail. The preliminary experimental results indicate that the proposed imaging approach significantly increases the processing performance of MUSER and generates images with high-quality, which can meet the requirements of the MUSER data processing. Supported by the National Key Research and Development Program of China (2016YFE0100300), the Joint Research Fund in Astronomy (No. U1531132, U1631129, U1231205) under cooperative agreement between the National Natural Science Foundation of China (NSFC) and the Chinese Academy of Sciences (CAS), the National Natural Science Foundation of China (Nos. 11403009 and 11463003).

  7. gr-MRI: A software package for magnetic resonance imaging using software defined radios

    Science.gov (United States)

    Hasselwander, Christopher J.; Cao, Zhipeng; Grissom, William A.

    2016-09-01

    The goal of this work is to develop software that enables the rapid implementation of custom MRI spectrometers using commercially-available software defined radios (SDRs). The developed gr-MRI software package comprises a set of Python scripts, flowgraphs, and signal generation and recording blocks for GNU Radio, an open-source SDR software package that is widely used in communications research. gr-MRI implements basic event sequencing functionality, and tools for system calibrations, multi-radio synchronization, and MR signal processing and image reconstruction. It includes four pulse sequences: a single-pulse sequence to record free induction signals, a gradient-recalled echo imaging sequence, a spin echo imaging sequence, and an inversion recovery spin echo imaging sequence. The sequences were used to perform phantom imaging scans with a 0.5 Tesla tabletop MRI scanner and two commercially-available SDRs. One SDR was used for RF excitation and reception, and the other for gradient pulse generation. The total SDR hardware cost was approximately 2000. The frequency of radio desynchronization events and the frequency with which the software recovered from those events was also measured, and the SDR's ability to generate frequency-swept RF waveforms was validated and compared to the scanner's commercial spectrometer. The spin echo images geometrically matched those acquired using the commercial spectrometer, with no unexpected distortions. Desynchronization events were more likely to occur at the very beginning of an imaging scan, but were nearly eliminated if the user invoked the sequence for a short period before beginning data recording. The SDR produced a 500 kHz bandwidth frequency-swept pulse with high fidelity, while the commercial spectrometer produced a waveform with large frequency spike errors. In conclusion, the developed gr-MRI software can be used to develop high-fidelity, low-cost custom MRI spectrometers using commercially-available SDRs.

  8. gr-MRI: A software package for magnetic resonance imaging using software defined radios.

    Science.gov (United States)

    Hasselwander, Christopher J; Cao, Zhipeng; Grissom, William A

    2016-09-01

    The goal of this work is to develop software that enables the rapid implementation of custom MRI spectrometers using commercially-available software defined radios (SDRs). The developed gr-MRI software package comprises a set of Python scripts, flowgraphs, and signal generation and recording blocks for GNU Radio, an open-source SDR software package that is widely used in communications research. gr-MRI implements basic event sequencing functionality, and tools for system calibrations, multi-radio synchronization, and MR signal processing and image reconstruction. It includes four pulse sequences: a single-pulse sequence to record free induction signals, a gradient-recalled echo imaging sequence, a spin echo imaging sequence, and an inversion recovery spin echo imaging sequence. The sequences were used to perform phantom imaging scans with a 0.5Tesla tabletop MRI scanner and two commercially-available SDRs. One SDR was used for RF excitation and reception, and the other for gradient pulse generation. The total SDR hardware cost was approximately $2000. The frequency of radio desynchronization events and the frequency with which the software recovered from those events was also measured, and the SDR's ability to generate frequency-swept RF waveforms was validated and compared to the scanner's commercial spectrometer. The spin echo images geometrically matched those acquired using the commercial spectrometer, with no unexpected distortions. Desynchronization events were more likely to occur at the very beginning of an imaging scan, but were nearly eliminated if the user invoked the sequence for a short period before beginning data recording. The SDR produced a 500kHz bandwidth frequency-swept pulse with high fidelity, while the commercial spectrometer produced a waveform with large frequency spike errors. In conclusion, the developed gr-MRI software can be used to develop high-fidelity, low-cost custom MRI spectrometers using commercially-available SDRs. Copyright

  9. Continuum Nanofluidics

    DEFF Research Database (Denmark)

    Hansen, Jesper S; Dyre, Jeppe C; Daivis, Peter

    2015-01-01

    This paper introduces the fundamental continuum theory governing momentum transport in isotropic nanofluidic systems. The theory is an extension of the classical Navier-Stokes equation, and includes coupling between translational and rotational degrees of freedom as well as nonlocal response...... functions that incorporate spatial correlations. The continuum theory is compared with molecular dynamics simulation data for both relaxation processes and fluid flows, showing excellent agreement on the nanometer length scale. We also present practical tools to estimate when the extended theory should...

  10. The Co-Evolution of Star Formation and Powerful Radio Activity in Galaxies During Radio-Mode Feedback

    Science.gov (United States)

    O'Dea, Christopher

    2017-08-01

    Feedback from radio sources is thought to be a key ingredient in determining the shape of the galaxy luminosity function. Compact Steep Spectrum (CSS) radio sources are galactic scale (1-20 kpc) and so probe radio source feedback to the host galaxy. We propose to carry out WFC3 UV imaging of the line-free continuum between [CIII] 1909 and MgII 2798, as well as WFC3 line-free optical continuum imaging, in nine CSS radio sources. Following our pilot study that detected spatially extended UV radiation in 3/3 CSS sources, we propose observations which will increase our total sample size by a factor of 4. Imaging the UV continuum from hot massive stars is the best way to study recently triggered and ongoing star formation. We will map in detail the star formation regions in relation to the radio structures and multiwavelength properties of the sources. The high spatial resolution will allow us to separate morphologically and characterize the generic star formation which is due to gas infall, and that which is due to triggering by the radio source.

  11. Chimenea and other tools: Automated imaging of multi-epoch radio-synthesis data with CASA

    Science.gov (United States)

    Staley, T. D.; Anderson, G. E.

    2015-11-01

    In preparing the way for the Square Kilometre Array and its pathfinders, there is a pressing need to begin probing the transient sky in a fully robotic fashion using the current generation of radio telescopes. Effective exploitation of such surveys requires a largely automated data-reduction process. This paper introduces an end-to-end automated reduction pipeline, AMIsurvey, used for calibrating and imaging data from the Arcminute Microkelvin Imager Large Array. AMIsurvey makes use of several component libraries which have been packaged separately for open-source release. The most scientifically significant of these is chimenea, which implements a telescope-agnostic algorithm for automated imaging of pre-calibrated multi-epoch radio-synthesis data, of the sort typically acquired for transient surveys or follow-up. The algorithm aims to improve upon standard imaging pipelines by utilizing iterative RMS-estimation and automated source-detection to avoid so called 'Clean-bias', and makes use of CASA subroutines for the underlying image-synthesis operations. At a lower level, AMIsurvey relies upon two libraries, drive-ami and drive-casa, built to allow use of mature radio-astronomy software packages from within Python scripts. While targeted at automated imaging, the drive-casa interface can also be used to automate interaction with any of the CASA subroutines from a generic Python process. Additionally, these packages may be of wider technical interest beyond radio-astronomy, since they demonstrate use of the Python library pexpect to emulate terminal interaction with an external process. This approach allows for rapid development of a Python interface to any legacy or externally-maintained pipeline which accepts command-line input, without requiring alterations to the original code.

  12. High-Resolution Radio Imaging of Gravitational Lensing Candidates in the 1 Jansky BL Lacertae Sample

    Science.gov (United States)

    Rector, Travis A.; Stocke, John T.

    2003-05-01

    While BL Lacertae objects are widely believed to be highly beamed, low-luminosity radio galaxies, many radio-selected BL Lac objects have extended radio power levels and optical emission lines that are too luminous to be low-luminosity radio galaxies. In addition, Stocke & Rector discovered an excess of Mg II absorption systems along BL Lac sight lines compared with quasars, suggesting that gravitational lensing may be another means of creating the BL Lac phenomenon in some cases. We present a search for gravitationally lensed BL Lac objects with deep, high-resolution, two-frequency VLA radio maps of seven lensing candidates from the 1 Jy BL Lac sample. We find that none of these objects are resolved into an Einstein ring like B0218+357, nor do any show multiple images of the core. All of the lensing candidates that were resolved show a flat-spectrum core and very unusual, steep-spectrum extended morphology that is incompatible with a multiply lensed system. Thus, while these observations do not rule out microlensing, no macrolensing is observed.

  13. Direct Imaging of the Water Snow Line at the Time of Planet Formation using Two ALMA Continuum Bands

    Science.gov (United States)

    Banzatti, A.; Pinilla, P.; Ricci, L.; Pontoppidan, K. M.; Birnstiel, T.; Ciesla, F.

    2015-12-01

    Molecular snow lines in protoplanetary disks have been studied theoretically for decades because of their importance in shaping planetary architectures and compositions. The water snow line lies in the planet formation region at ≲10 AU, and so far its location has been estimated only indirectly from spatially unresolved spectroscopy. This work presents a proof-of-concept method to directly image the water snow line in protoplanetary disks through its physical and chemical imprint on the local dust properties. We adopt a physical disk model that includes dust coagulation, fragmentation, drift, and a change in fragmentation velocities of a factor of 10 between dry silicates and icy grains as found by laboratory work. We find that the presence of a water snow line leads to a sharp discontinuity in the radial profile of the dust emission spectral index αmm due to replenishment of small grains through fragmentation. We use the ALMA simulator to demonstrate that this effect can be observed in protoplanetary disks using spatially resolved ALMA images in two continuum bands. We explore the model dependence on the disk viscosity and find that the spectral index reveals the water snow line for a wide range of conditions, with opposite trends when the emission is optically thin rather than thick. If the disk viscosity is low (αvisc structure with a minimum at αmm ˜ 2 in the optically thick regime, possibly similar to what has been measured with ALMA in the innermost region of the HL Tau disk.

  14. Vector Antenna and Maximum Likelihood Imaging for Radio Astronomy

    Science.gov (United States)

    2016-03-05

    Deputy Director of Smart Collection at IARPA/ODNI. He began his career as a precision instrument designer at Hewlett Packard and then at Emerson ...2. Vector antenna maximizes the statistics collected from a single point in space. This maximizes the utility of a single satellite short of...multiple satellites the ability to collect these statistics with a vector antenna allows radiometric imaging to be performed with just a single

  15. Exploring three faint source detections methods for aperture synthesis radio images

    Science.gov (United States)

    Peracaula, M.; Torrent, A.; Masias, M.; Lladó, X.; Freixenet, J.; Martí, J.; Sánchez-Sutil, J. R.; Muñoz-Arjonilla, A. J.; Paredes, J. M.

    2015-04-01

    Wide-field radio interferometric images often contain a large population of faint compact sources. Due to their low intensity/noise ratio, these objects can be easily missed by automated detection methods, which have been classically based on thresholding techniques after local noise estimation. The aim of this paper is to present and analyse the performance of several alternative or complementary techniques to thresholding. We compare three different algorithms to increase the detection rate of faint objects. The first technique consists of combining wavelet decomposition with local thresholding. The second technique is based on the structural behaviour of the neighbourhood of each pixel. Finally, the third algorithm uses local features extracted from a bank of filters and a boosting classifier to perform the detections. The methods' performances are evaluated using simulations and radio mosaics from the Giant Metrewave Radio Telescope and the Australia Telescope Compact Array. We show that the new methods perform better than well-known state of the art methods such as SEXTRACTOR, SAD and DUCHAMP at detecting faint sources of radio interferometric images.

  16. Comparative study on visible-OCT imagings using a LED and a super-continuum laser with a wavelength-tunable filter

    Science.gov (United States)

    Tokunaga, Etsuko; Iwai, Toshiaki

    2017-04-01

    We have investigated imaging characteristics of full-field OCT (FFF-OCT) using a LED and aa super-continuum (SC) laser with a wavelength-tunable filter. The wavelength selectivity in visible range enables to take spectroscopic tomographic images. It has been considered that the application of the LED-OOCT system might be restricted due to the low spatial coherence and illuminating power. Comparative study of imaging characteristics of the OCT images taken the RGB-visible LED and the SC laser demonstrates superiority of the LED illumination in reconstruction of detail structures.

  17. Continuum mechanics

    CERN Document Server

    Spencer, A J M

    2004-01-01

    The mechanics of fluids and the mechanics of solids represent the two major areas of physics and applied mathematics that meet in continuum mechanics, a field that forms the foundation of civil and mechanical engineering. This unified approach to the teaching of fluid and solid mechanics focuses on the general mechanical principles that apply to all materials. Students who have familiarized themselves with the basic principles can go on to specialize in any of the different branches of continuum mechanics. This text opens with introductory chapters on matrix algebra, vectors and Cartesian ten

  18. Variational Methods for Discontinuous Structures : Applications to Image Segmentation, Continuum Mechanics

    CERN Document Server

    Tomarelli, Franco

    1996-01-01

    In recent years many researchers in material science have focused their attention on the study of composite materials, equilibrium of crystals and crack distribution in continua subject to loads. At the same time several new issues in computer vision and image processing have been studied in depth. The understanding of many of these problems has made significant progress thanks to new methods developed in calculus of variations, geometric measure theory and partial differential equations. In particular, new technical tools have been introduced and successfully applied. For example, in order to describe the geometrical complexity of unknown patterns, a new class of problems in calculus of variations has been introduced together with a suitable functional setting: the free-discontinuity problems and the special BV and BH functions. The conference held at Villa Olmo on Lake Como in September 1994 spawned successful discussion of these topics among mathematicians, experts in computer science and material scientis...

  19. Imaging spectroscopy of type U and J solar radio bursts with LOFAR

    Science.gov (United States)

    Reid, Hamish A. S.; Kontar, Eduard P.

    2017-10-01

    Context. Radio U-bursts and J-bursts are signatures of electron beams propagating along magnetic loops confined to the corona. The more commonly observed type III radio bursts are signatures of electron beams propagating along magnetic loops that extend into interplanetary space. Given the prevalence of solar magnetic flux to be closed in the corona, why type III bursts are more frequently observed than U-bursts or J-bursts is an outstanding question. Aims: We use Low-Frequency Array (LOFAR) imaging spectroscopy between 30-80 MHz of low-frequency U-bursts and J-bursts, for the first time, to understand why electron beams travelling along coronal loops produce radio emission less often. Radio burst observations provide information not only about the exciting electron beams but also about the structure of large coronal loops with densities that are too low for standard extreme ultraviolet (EUV) or X-ray analysis. Methods: We analysed LOFAR images of a sequence of two J-bursts and one U-burst. The different radio source positions were used to model the spatial structure of the guiding magnetic flux tube and then deduce the energy range of the exciting electron beams without the assumption of a standard density model. We also estimated the electron density along the magnetic flux rope and compared it to coronal models. Results: The radio sources infer a magnetic loop that is 1 solar radius in altitude with the highest frequency sources starting around 0.6 solar radii. Electron velocities were found between 0.13 c and 0.24 c with the front of the electron beam travelling faster than the back of the electron beam. The velocities correspond to energy ranges within the beam from 0.7-11 keV to 0.7-43 keV. The density along the loop is higher than typical coronal density models and the density gradient is smaller. Conclusions: We found that a more restrictive range of accelerated beam and background plasma parameters can result in U-bursts or J-bursts, causing type III

  20. Using Near-IR Imaging to Probe Accretion-Disk Physics in Powerful Radio Sources

    Science.gov (United States)

    Koekemoer, Anton; O'Dea, Chris; Baum, Stefi

    1999-08-01

    An intriguing question in the study of powerful radio galaxies concerns the reason for their wide diversity of properties: is this related predominantly to external environmental effects, or to intrinsic differences in their central engines and accretion processes? We propose to address this question by using the 2.1m + ONIS to obtain J, H and K imaging of two samples of FR I and FR II radio galaxies, to measure the luminosity and colors of warm circumnuclear dust and determine the near- IR structure and environment of the surrounding host galaxies. The dust absorbs radiation from the AGN and re-radiates it in the near-IR, which can thus be used as a diagnostic of the AGN radiant energy output. This will be compared with the AGN kinetic energy output in the form of radio jets. Our two samples are statistically well-matched in both radio power and redshift space, allowing us to carry out statistical comparisons between AGN properties such as the radiant / kinetic energy conversion, as well as large-scale host galaxy properties. This will indicate whether differences between these classes of active galaxies are related primarily to the central engine, or instead dominated by the large-scale properties of the host galaxy and its environment.

  1. Improved eigensubspace-based approach for radio frequency interference filtering of synthetic aperture radar images

    Science.gov (United States)

    Zhou, Chunhui; Li, Fei; Li, Ning; Zheng, Huifang; Wang, Robert; Wang, Xiangyu

    2017-04-01

    The radio frequency interference (RFI) has an adverse effect on the useful signals, which can degrade the image quality seriously. An improved eigensubspace-based approach for RFI filtering of synthetic aperture radar images is developed. In the preprocessing stage of the proposed approach, the data sets that need subsequent processing can be selected in both frequency and time domain. Then, the data can be processed by the traditional eigensubspace-based approach. Compared with the traditional eigensubspace-based approach, our approach can work more efficiently and effectively.

  2. Radio Surveys: an Overview

    NARCIS (Netherlands)

    Morganti, Raffaella

    Radio astronomy has provided important surveys that have made possible key (and sometimes serendipitous) discoveries. I will briefly mention some of the past continuum and line (HI) radio surveys as well as new, on-going surveys and surveys planned for the near future. This new generation of large

  3. Trabecular bone characterization on the continuum of plates and rods using in vivo MR imaging and volumetric topological analysis

    Science.gov (United States)

    Chen, Cheng; Jin, Dakai; Liu, Yinxiao; Wehrli, Felix W.; Chang, Gregory; Snyder, Peter J.; Regatte, Ravinder R.; Saha, Punam K.

    2016-09-01

    Osteoporosis is associated with increased risk of fractures, which is clinically defined by low bone mineral density. Increasing evidence suggests that trabecular bone (TB) micro-architecture is an important determinant of bone strength and fracture risk. We present an improved volumetric topological analysis algorithm based on fuzzy skeletonization, results of its application on in vivo MR imaging, and compare its performance with digital topological analysis. The new VTA method eliminates data loss in the binarization step and yields accurate and robust measures of local plate-width for individual trabeculae, which allows classification of TB structures on the continuum between perfect plates and rods. The repeat-scan reproducibility of the method was evaluated on in vivo MRI of distal femur and distal radius, and high intra-class correlation coefficients between 0.93 and 0.97 were observed. The method’s ability to detect treatment effects on TB micro-architecture was examined in a 2 years testosterone study on hypogonadal men. It was observed from experimental results that average plate-width and plate-to-rod ratio significantly improved after 6 months and the improvement was found to continue at 12 and 24 months. The bone density of plate-like trabeculae was found to increase by 6.5% (p  =  0.06), 7.2% (p  =  0.07) and 16.2% (p  =  0.003) at 6, 12, 24 months, respectively. While the density of rod-like trabeculae did not change significantly, even at 24 months. A comparative study showed that VTA has enhanced ability to detect treatment effects in TB micro-architecture as compared to conventional method of digital topological analysis for plate/rod characterization in terms of both percent change and effect-size.

  4. Wavelet-based compression with ROI coding support for mobile access to DICOM images over heterogeneous radio networks.

    Science.gov (United States)

    Maglogiannis, Ilias; Doukas, Charalampos; Kormentzas, George; Pliakas, Thomas

    2009-07-01

    Most of the commercial medical image viewers do not provide scalability in image compression and/or region of interest (ROI) encoding/decoding. Furthermore, these viewers do not take into consideration the special requirements and needs of a heterogeneous radio setting that is constituted by different access technologies [e.g., general packet radio services (GPRS)/ universal mobile telecommunications system (UMTS), wireless local area network (WLAN), and digital video broadcasting (DVB-H)]. This paper discusses a medical application that contains a viewer for digital imaging and communications in medicine (DICOM) images as a core module. The proposed application enables scalable wavelet-based compression, retrieval, and decompression of DICOM medical images and also supports ROI coding/decoding. Furthermore, the presented application is appropriate for use by mobile devices activating in heterogeneous radio settings. In this context, performance issues regarding the usage of the proposed application in the case of a prototype heterogeneous system setup are also discussed.

  5. Non-convex optimization for self-calibration of direction-dependent effects in radio interferometric imaging

    Science.gov (United States)

    Repetti, Audrey; Birdi, Jasleen; Dabbech, Arwa; Wiaux, Yves

    2017-10-01

    Radio interferometric imaging aims to estimate an unknown sky intensity image from degraded observations, acquired through an antenna array. In the theoretical case of a perfectly calibrated array, it has been shown that solving the corresponding imaging problem by iterative algorithms based on convex optimization and compressive sensing theory can be competitive with classical algorithms such as clean. However, in practice, antenna-based gains are unknown and have to be calibrated. Future radio telescopes, such as the Square Kilometre Array, aim at improving imaging resolution and sensitivity by orders of magnitude. At this precision level, the direction-dependency of the gains must be accounted for, and radio interferometric imaging can be understood as a blind deconvolution problem. In this context, the underlying minimization problem is non-convex, and adapted techniques have to be designed. In this work, leveraging recent developments in non-convex optimization, we propose the first joint calibration and imaging method in radio interferometry, with proven convergence guarantees. Our approach, based on a block-coordinate forward-backward algorithm, jointly accounts for visibilities and suitable priors on both the image and the direction-dependent effects (DDEs). As demonstrated in recent works, sparsity remains the prior of choice for the image, while DDEs are modelled as smooth functions of the sky, I.e. spatially band-limited. Finally, we show through simulations the efficiency of our method, for the reconstruction of both images of point sources and complex extended sources. matlab code is available on GitHub.

  6. Radio-adaptive Response in Myocardial Perfusion Imaging Induced by Technetium-99m.

    Science.gov (United States)

    Shirazi, Mohammad Mehdi; Shabestani-Monfared, Ali; Shahidi, Maryam; Amiri, Mehrangiz; Abedi, Seyed Mohammad; Borzoueisileh, Sajad; Gorji, Kourosh Ebrahim Nejad

    2017-01-01

    Low dose radiation will induce adaptation and following exposure to an adaptive dose, the cells are more resistance to following challenging doses. This phenomenon is known as radio-adaptive response. The aim of this study was to investigate the percentage of apoptotic cells in the peripheral blood samples of the patients which undergo myocardial perfusion imaging (MPI) with technetium-99m (Tc-99m) before thallium scan to assess the induction of radio-adaptive response. In this study, 97 samples from 74 patients, referred to nuclear medicine center of Mazandaran Heart Hospital for MPI, which had no history of diagnostic, therapeutic, occupational, and radioactive exposures during past 2 years, were provided. The participants were classified into four groups including control, patients which were scanned solely with technetium, the patients which examined by thallium and the last group were the patients that examined by technetium followed by thallium. Then 2 ml Peripheral blood samples were obtained, and after 24 h incubating, the samples were studied by neutral comet assay. Statistical analysis was carried out using Student's t-test along with one-way analysis of variance. The mean percentage of apoptotic cells in the exposed groups were higher than the control. Furthermore, among exposed groups, the apoptotic cells in thallium group were more than others and this index was significantly lower in the group which was undergone technetium administration before thallium scan. These findings suggest that exposure to Tc-99m could induce a radio-adaptive response against the exposure of thallium-201.

  7. RadioAstron space VLBI imaging of polarized radio emission in the high-redshift quasar 0642+449 at 1.6 GHz

    Science.gov (United States)

    Lobanov, A. P.; Gómez, J. L.; Bruni, G.; Kovalev, Y. Y.; Anderson, J.; Bach, U.; Kraus, A.; Zensus, J. A.; Lisakov, M. M.; Sokolovsky, K. V.; Voytsik, P. A.

    2015-11-01

    Context. Polarization of radio emission in extragalactic jets at a sub-milliarcsecond angular resolution holds important clues for understanding the structure of the magnetic field in the inner regions of the jets and in close vicinity of the supermassive black holes in the centers of active galaxies. Aims: Space VLBI observations provide a unique tool for polarimetric imaging at a sub-milliarcsecond angular resolution and studying the properties of magnetic field in active galactic nuclei on scales of less than 104 gravitational radii. Methods: A space VLBI observation of high-redshift quasar TXS 0642+449 (OH 471), made at a wavelength of 18 cm (frequency of 1.6 GHz) as part of the early science programme (ESP) of the RadioAstron mission, is used here to test the polarimetric performance of the orbiting Space Radio Telescope (SRT) employed by the mission, to establish a methodology for making full Stokes polarimetry with space VLBI at 1.6 GHz, and to study the polarized emission in the target object on sub-milliarcsecond scales. Results: Polarization leakage of the SRT at 18 cm is found to be within 9% in amplitude, demonstrating the feasibility of high fidelity polarization imaging with RadioAstron at this wavelength. A polarimetric image of 0642+449 with a resolution of 0.8 mas (signifying an ~4 times improvement over ground VLBI observations at the same wavelength) is obtained. The image shows a compact core-jet structure with low (≈2%) polarization and predominantly transverse magnetic field in the nuclear region. The VLBI data also uncover a complex structure of the nuclear region, with two prominent features possibly corresponding to the jet base and a strong recollimation shock. The maximum brightness temperature at the jet base can be as high as 4 × 1013 K.

  8. Simultaneous PET/MR imaging with a radio frequency-penetrable PET insert.

    Science.gov (United States)

    Grant, Alexander M; Lee, Brian J; Chang, Chen-Ming; Levin, Craig S

    2017-01-01

    A brain sized radio frequency (RF)-penetrable PET insert has been designed for simultaneous operation with MRI systems. This system takes advantage of electro-optical coupling and battery power to electrically float the PET insert relative to the MRI ground, permitting RF signals to be transmitted through small gaps between the modules that form the PET ring. This design facilitates the use of the built-in body coil for RF transmission and thus could be inserted into any existing MR site wishing to achieve simultaneous PET/MR imaging. The PET detectors employ nonmagnetic silicon photomultipliers in conjunction with a compressed sensing signal multiplexing scheme, and optical fibers to transmit analog PET detector signals out of the MRI room for decoding, processing, and image reconstruction. The PET insert was first constructed and tested in a laboratory benchtop setting, where tomographic images of a custom resolution phantom were successfully acquired. The PET insert was then placed within a 3T body MRI system, and tomographic resolution/contrast phantom images were acquired both with only the B0 field present, and under continuous pulsing from different MR imaging sequences. The resulting PET images have comparable contrast-to-noise ratios (CNR) under all MR pulsing conditions: The maximum percent CNR relative difference for each rod type among all four PET images acquired in the MRI system has a mean of 14.0 ± 7.7%. MR images were successfully acquired through the RF-penetrable PET shielding using only the built-in MR body coil, suggesting that simultaneous imaging is possible without significant mutual interference. These results show promise for this technology as an alternative to costly integrated PET/MR scanners; a PET insert that is compatible with any existing clinical MRI system could greatly increase the availability, accessibility, and dissemination of PET/MR. © 2016 American Association of Physicists in Medicine.

  9. Continuum Physics

    CERN Document Server

    Hertel, Peter

    2012-01-01

    This small book on the properties of continuously distributed matter covers a huge field. It sets out the governing principles of continuum physics and illustrates them by carefully chosen examples. These examples comprise structural mechanics and elasticity, fluid media, electricity and optics, thermoelectricity, fluctuation phenomena and more, from Archimedes' principle via Brownian motion to white dwarfs. Metamaterials, pattern formation by reaction-diffusion and surface plasmon polaritons are dealt with as well as classical topics such as Stokes' formula, beam bending and buckling, crystal optics and electro- and magnetooptic effects, dielectric waveguides, Ohm's law, surface acoustic waves, to mention just some.   The set of balance equations for content, flow and production of particles, mass, charge, momentum, energy and entropy is augmented by material, or constitutive equations. They describe entire classes of materials, such as viscid fluids and gases, elastic media, dielectrics or electrical con...

  10. Design of catheter radio frequency coils using coaxial transmission line resonators for interventional neurovascular MR imaging.

    Science.gov (United States)

    Zhang, Xiaoliang; Martin, Alastair; Jordan, Caroline; Lillaney, Prasheel; Losey, Aaron; Pang, Yong; Hu, Jeffrey; Wilson, Mark; Cooke, Daniel; Hetts, Steven W

    2017-04-01

    It is technically challenging to design compact yet sensitive miniature catheter radio frequency (RF) coils for endovascular interventional MR imaging. In this work, a new design method for catheter RF coils is proposed based on the coaxial transmission line resonator (TLR) technique. Due to its distributed circuit, the TLR catheter coil does not need any lumped capacitors to support its resonance, which simplifies the practical design and construction and provides a straightforward technique for designing miniature catheter-mounted imaging coils that are appropriate for interventional neurovascular procedures. The outer conductor of the TLR serves as an RF shield, which prevents electromagnetic energy loss, and improves coil Q factors. It also minimizes interaction with surrounding tissues and signal losses along the catheter coil. To investigate the technique, a prototype catheter coil was built using the proposed coaxial TLR technique and evaluated with standard RF testing and measurement methods and MR imaging experiments. Numerical simulation was carried out to assess the RF electromagnetic field behavior of the proposed TLR catheter coil and the conventional lumped-element catheter coil. The proposed TLR catheter coil was successfully tuned to 64 MHz for proton imaging at 1.5 T. B1 fields were numerically calculated, showing improved magnetic field intensity of the TLR catheter coil over the conventional lumped-element catheter coil. MR images were acquired from a dedicated vascular phantom using the TLR catheter coil and also the system body coil. The TLR catheter coil is able to provide a significant signal-to-noise ratio (SNR) increase (a factor of 200 to 300) over its imaging volume relative to the body coil. Catheter imaging RF coil design using the proposed coaxial TLR technique is feasible and advantageous in endovascular interventional MR imaging applications.

  11. The first VLBI image of an infrared-faint radio source

    Science.gov (United States)

    Middelberg, E.; Norris, R. P.; Tingay, S.; Mao, M. Y.; Phillips, C. J.; Hotan, A. W.

    2008-11-01

    Context: We investigate the joint evolution of active galactic nuclei and star formation in the Universe. Aims: In the 1.4 GHz survey with the Australia Telescope Compact Array of the Chandra Deep Field South and the European Large Area ISO Survey - S1 we have identified a class of objects which are strong in the radio but have no detectable infrared and optical counterparts. This class has been called Infrared-Faint Radio Sources, or IFRS. 53 sources out of 2002 have been classified as IFRS. It is not known what these objects are. Methods: To address the many possible explanations as to what the nature of these objects is we have observed four sources with the Australian Long Baseline Array. Results: We have detected and imaged one of the four sources observed. Assuming that the source is at a high redshift, we find its properties in agreement with properties of Compact Steep Spectrum sources. However, due to the lack of optical and infrared data the constraints are not particularly strong.

  12. An accelerated splitting algorithm for radio-interferometric imaging: when natural and uniform weighting meet

    Science.gov (United States)

    Onose, Alexandru; Dabbech, Arwa; Wiaux, Yves

    2017-07-01

    Next-generation radio interferometers, like the Square Kilometre Array, will acquire large amounts of data with the goal of improving the size and sensitivity of the reconstructed images by orders of magnitude. The efficient processing of large-scale data sets is of great importance. We propose an acceleration strategy for a recently proposed primal-dual distributed algorithm. A preconditioning approach can incorporate into the algorithmic structure both the sampling density of the measured visibilities and the noise statistics. Using the sampling density information greatly accelerates the convergence speed, especially for highly non-uniform sampling patterns, while relying on the correct noise statistics optimizes the sensitivity of the reconstruction. In connection to clean, our approach can be seen as including in the same algorithmic structure both natural and uniform weighting, thereby simultaneously optimizing both the resolution and the sensitivity. The method relies on a new non-Euclidean proximity operator for the data fidelity term, that generalizes the projection on to the ℓ2 ball where the noise lives for naturally weighted data, to the projection on to a generalized ellipsoid incorporating sampling density information through uniform weighting. Importantly, this non-Euclidean modification is only an acceleration strategy to solve the convex imaging problem with data fidelity dictated only by noise statistics. We show through simulations with realistic sampling patterns the acceleration obtained using the preconditioning. We also investigate the algorithm performance for the reconstruction of the 3C129 radio galaxy from real visibilities and compare with multiscale clean, showing better sensitivity and resolution. Our matlab code is available online on GitHub.

  13. Global VLBI Observations of Weak Extragalactic Radio Sources: Imaging Candidates to Align the VLBI and Gaia Frames

    Science.gov (United States)

    Bourda, Geraldine; Collioud, Arnaud; Charlot, Patrick; Porcas, Richard; Garrington, Simon

    2010-01-01

    The space astrometry mission Gaia will construct a dense optical QSO-based celestial reference frame. For consistency between optical and radio positions, it will be important to align the Gaia and VLBI frames (International Celestial Reference Frame) with the highest accuracy. In this respect, it is found that only 10% of the ICRF sources are suitable to establish this link (70 sources), either because most of the ICRF sources are not bright enough at optical wavelengths or because they show extended radio emission which precludes reaching the highest astrometric accuracy. In order to improve the situation, we initiated a multi-step VLBI observational project, dedicated to finding additional suitable radio sources for aligning the two frames. The sample consists of about 450 optically-bright radio sources, typically 20 times weaker than the ICRF sources, which have been selected by cross-correlating optical and radio catalogs. The initial observations, aimed at checking whether these sources are detectable with VLBI, and conducted with the European VLBI Network (EVN) in 2007, showed an excellent 90% detection rate. This paper reports on global VLBI observations carried out in March 2008 to image 105 from the 398 previously detected sources. All sources were successfully imaged, revealing compact VLBI structure for about half of them, which is very promising for the future.

  14. Deep Interior: Radio Reflection Tomographic Imaging of Earth-Crossing Asteroids

    Science.gov (United States)

    Asphaug, E.; Belton, M.; Safaeinili, A.; Klaasen, K.; Ostro, S.; Yeomans, D.; Plaut, J.

    2004-12-01

    Near-Earth Objects (NEOs) present an important scientific question and an intriguing space hazard. They are scrutinized by a number of large, dedicated groundbased telescopes, and their diverse compositions are represented by thousands of well-studied meteorites. A successful program of NEO spacecraft exploration has begun, and we are proposing Deep Interior as the next logical step. Our mission objective is to image the deep interior structure of two NEOs using radio reflection tomography (RRT), in order to explore the record of asteroid origin and impact evolution, and to test the fundamental hypothesis that these important members of the solar system are rubble piles rather than consolidated bodies. Asteroid Interiors. Our mission's RRT technique is like a CAT scan from orbit. Closely sampled radar echoes yield volumetric maps of mechanical and compositional boundaries, and measure interior material dielectric properties. Exteriors. We use color imaging to explore the surface expressions of unit boundaries, in order to relate interior radar imaging to what is observable from spacecraft imaging and from Earth. Gravity and high fidelity geodesy are used to explore how interior structure is expressed in shape, density, mass distribution and spin. Diversity. We first visit a common, primitive, S-type asteroid. We next visit an asteroid that was perhaps blasted from the surface of a differentiated asteroid. We attain an up-close and inside look at two taxonomic archetypes spanning an important range of NEO mass and spin rate. Scientific focus is achieved by keeping our payload simple: Radar. A 30-m (tip-to-tip) cross-dipole antenna system operates at 5 and 15-MHz, with electronics heritage from JPL's MARSIS contribution to Mars Express, and antenna heritage from IMAGE and LACE. The 5-MHz channel is designed to penetrate >1 km of basaltic rock, and 15-MHz penetrates a few 100 m or more. They bracket the diversity of solar system materials that we are likely to

  15. THE Q/U IMAGING EXPERIMENT: POLARIZATION MEASUREMENTS OF RADIO SOURCES AT 43 AND 95 GHz

    Energy Technology Data Exchange (ETDEWEB)

    Huffenberger, K. M. [Department of Physics, Florida State University, P.O. Box 3064350, Tallahassee, FL 32306-4350 (United States); Araujo, D.; Zwart, J. T. L. [Department of Physics and Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Bischoff, C.; Buder, I. [Kavli Institute for Cosmological Physics, Department of Physics, Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637 (United States); Chinone, Y.; Hasegawa, M. [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Cleary, K. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 E. California Blvd M/C 249-17, Pasadena, CA 91125 (United States); Kusaka, A. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Monsalve, R. [School of Earth and Space Exploration, Arizona State University, 781 E. Terrace Road, Tempe, AZ 85287 (United States); Næss, S. K. [Department of Astrophysics, University of Oxford, Keble Road, Oxford, OX1 3RH (United Kingdom); Newburgh, L. B. [Dunlap Institute, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Reeves, R. [CePIA, Departamento de Astronomía, Universidad de Concepción (Chile); Ruud, T. M.; Eriksen, H. K. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway); Wehus, I. K.; Gaier, T. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Dickinson, C. [Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Gundersen, J. O., E-mail: huffenbe@physics.fsu.edu [Department of Physics, University of Miami, 1320 Campo Sano Drive, Coral Gables, FL 33146 (United States); Collaboration: QUIET Collaboration; and others

    2015-06-10

    We present polarization measurements of extragalactic radio sources observed during the cosmic microwave background polarization survey of the Q/U Imaging Experiment (QUIET), operating at 43 GHz (Q-band) and 95 GHz (W-band). We examine sources selected at 20 GHz from the public, >40 mJy catalog of the Australia Telescope (AT20G) survey. There are ∼480 such sources within QUIET’s four low-foreground survey patches, including the nearby radio galaxies Centaurus A and Pictor A. The median error on our polarized flux density measurements is 30–40 mJy per Stokes parameter. At signal-to-noise ratio > 3 significance, we detect linear polarization for seven sources in Q-band and six in W-band; only 1.3 ± 1.1 detections per frequency band are expected by chance. For sources without a detection of polarized emission, we find that half of the sources have polarization amplitudes below 90 mJy (Q-band) and 106 mJy (W-band), at 95% confidence. Finally, we compare our polarization measurements to intensity and polarization measurements of the same sources from the literature. For the four sources with WMAP and Planck intensity measurements >1 Jy, the polarization fractions are above 1% in both QUIET bands. At high significance, we compute polarization fractions as much as 10%–20% for some sources, but the effects of source variability may cut that level in half for contemporaneous comparisons. Our results indicate that simple models—ones that scale a fixed polarization fraction with frequency—are inadequate to model the behavior of these sources and their contributions to polarization maps.

  16. Cosmological measurements with forthcoming radio continuum surveys

    CSIR Research Space (South Africa)

    Raccanelli, A

    2012-08-01

    Full Text Available , while the best measurements of dark energy models will come from galaxy autocorrelation function analyses. Using a combination of the EvolutionaryMap of the Universe (EMU) and WODAN to provide a full-sky survey, it will be possible to measure the dark...

  17. Optical imaging of airglow structure in equatorial plasma bubbles at radio scintillation scales

    Science.gov (United States)

    Holmes, J. M.; Pedersen, T.; Parris, R. T.; Stephens, B.; Caton, R. G.; Dao, E. V.; Kratochvil, S.; Morton, Y.; Xu, D.; Jiao, Y.; Taylor, S.; Carrano, C. S.

    2015-12-01

    Imagery of optical emissions from F-region plasma is one of the few means available todetermine plasma density structure in two dimensions. However, the smallest spatial scalesobservable with this technique are typically limited not by magnification of the lens or resolutionof the detector but rather by the optical throughput of the system, which drives the integrationtime, which in turn causes smearing of the features that are typically moving at speeds of 100m/s or more. In this paper we present high spatio-temporal imagery of equatorial plasma bubbles(EPBs) from an imaging system called the Large Aperture Ionospheric Structure Imager(LAISI), which was specifically designed to capture short-integration, high-resolution images ofF-region recombination airglow at λ557.7 nm. The imager features 8-inch diameter entranceoptics comprised of a unique F/0.87 lens, combined with a monolithic 8-inch diameterinterference filter and a 2x2-inch CCD detector. The LAISI field of view is approximately 30degrees. Filtered all-sky images at common airglow wavelengths are combined with magneticfield-aligned LAISI images, GNSS scintillation, and VHF scintillation data obtained atAscension Island (7.98S, 14.41W geographic). A custom-built, multi-constellation GNSS datacollection system was employed that sampled GPS L1, L2C, L5, GLONASS L1 and L2, BeidouB1, and Galileo E1 and E5a signals. Sophisticated processing software was able to maintainlock of all signals during strong scintillation, providing unprecedented spatial observability ofL band scintillation. The smallest-resolvable scale sizes above the noise floor in the EPBs, as viewed byLAISI, are illustrated for integration times of 1, 5 and 10 seconds, with concurrentzonal irregularity drift speeds from both spaced-receiver VHF measurements and single-stationGNSS measurements of S4 and σφ. These observable optical scale sizes are placed in thecontext of those that give rise to radio scintillation in VHF and L band signals.

  18. Image Reconstruction in Radio Astronomy with Non-Coplanar Synthesis Arrays

    Science.gov (United States)

    Goodrick, L.

    2015-03-01

    Traditional radio astronomy imaging techniques assume that the interferometric array is coplanar, with a small field of view, and that the two-dimensional Fourier relationship between brightness and visibility remains valid, allowing the Fast Fourier Transform to be used. In practice, to acquire more accurate data, the non-coplanar baseline effects need to be incorporated, as small height variations in the array plane introduces the w spatial frequency component. This component adds an additional phase shift to the incoming signals. There are two approaches to account for the non-coplanar baseline effects: either the full three-dimensional brightness and visibility model can be used to reconstruct an image, or the non-coplanar effects can be removed, reducing the three dimensional relationship to that of the two-dimensional one. This thesis describes and implements the w-projection and w-stacking algorithms. The aim of these algorithms is to account for the phase error introduced by non-coplanar synthesis arrays configurations, making the recovered visibilities more true to the actual brightness distribution model. This is done by reducing the 3D visibilities to a 2D visibility model. The algorithms also have the added benefit of wide-field imaging, although w-stacking supports a wider field of view at the cost of more FFT bin support. For w-projection, the w-term is accounted for in the visibility domain by convolving it out of the problem with a convolution kernel, allowing the use of the two-dimensional Fast Fourier Transform. Similarly, the w-Stacking algorithm applies a phase correction in the image domain to image layers to produce an intensity model that accounts for the non-coplanar baseline effects. This project considers the KAT7 array for simulation and analysis of the limitations and advantages of both the algorithms. Additionally, a variant of the Högbom CLEAN algorithm was used which employs contour trimming for extended source emission flagging. The

  19. Deep Interior Mission: Imaging the Interior of Near-Earth Asteroids Using Radio Reflection Tomography

    Science.gov (United States)

    Safaeinili, A.; Asphaug, E.; Rodriquez, E.; Gurrola, E.; Belton, M.; Klaasen, K.; Ostro, S.; Plaut, J.; Yeomans, D.

    2005-01-01

    Near-Earth asteroids are important exploration targets since they provide clues to the evolution of the solar system. They are also of interest since they present a clear danger to Earth. Our mission objective is to image the internal structure of two NEOs using radio reflection tomography (RRT) in order to explore the record of asteroid origin and impact evolution, and to test the fundamental hypothesis that some NEOs are rubble piles rather than consolidated bodies. Our mission s RRT technique is analogous to doing a CAT scan of the asteroid from orbit. Closely sampled radar echoes are processed to yield volumetric maps of mechanical and compositional boundaries, and to measure interior material dielectric properties. The RRT instrument is a radar that operates at 5 and 15 MHz with two 30-m (tip-to-tip) dipole antennas that are used in a cross-dipole configuration. The radar transmitter and receiver electronics have heritage from JPL's MARSIS contribution to Mars Express, and the antenna is similar to systems used in IMAGE and LACE missions. The 5-MHz channel is designed to penetrate greater than 1 km of basaltic rock, and 15-MHz penetrates a few hundred meters or more. In addition to RRT volumetric imaging, we use redundant color cameras to explore the surface expressions of unit boundaries, in order to relate interior radar imaging to what is observable from spacecraft imaging and from Earth. The camera also yields stereo color imaging for geology and RRT-related compositional analysis. Gravity and high fidelity geodesy are used to explore how interior structure is expressed in shape, density, mass distribution and spin. Ion thruster propulsion is utilized by Deep Interior to enable tomographic radar mapping of multiple asteroids. Within the Discovery AO scheduling parameters we identify two targets, S-type 1999 ND43 (approximately 500 m diameter) and V-type 3908 Nyx (approximately 1 km), asteroids whose compositions bracket the diversity of solar system

  20. Sub-Arcsecond Sub-mm Continuum Observations of Orion-KL

    Energy Technology Data Exchange (ETDEWEB)

    Beuther, H

    2004-06-25

    We present the first 865 {micro}m continuum image with sub-arcsecond resolution obtained with the Submillimeter Array. These data resolve the Orion-KL region into the hot core, the nearby radio source I, the sub-mm counterpart to the infrared source n (radio source L), and new sub-mm continuum sources. The radio to submillimeter emission from source I may be modeled as either the result of proton-electron free-free emission that is optically thick to {approx} 100 GHz plus dust emission that accounts for the majority of the submillimeter flux, or H{sup -} free-free emission that gives rise to a power-law spectrum with power-law index of {approx} 1.6. The latter model would indicate similar physical conditions as found in the inner circumstellar environment of Mira variable stars. Future sub-arcsecond observations at shorter sub-mm wavelengths should easily discriminate between these two possibilities. The sub-mm continuum emission toward source n can be interpreted in the framework of emission from an accretion disk.

  1. LOFAR imaging of Cygnus A - direct detection of a turnover in the hotspot radio spectra

    NARCIS (Netherlands)

    McKean, J.P.; Godfrey, L.E.H.; Vegetti, S.; Wise, M.W.; Morganti, R.; Bentum, Marinus Jan; Hardcastle, M.J.; Rafferty, D.; Anderson, J.; Avruch, I.M.; Beck, R.; Bell, M.E.; van Bemmel, I.; Bernardi, G.

    2016-01-01

    The low-frequency radio spectra of the hotspots within powerful radio galaxies can provide valuable information about the physical processes operating at the site of the jet termination. These processes are responsible for the dissipation of jet kinetic energy, particle acceleration, and

  2. Interaction of polar molecules with resonant radio frequency electric fields: imaging of the NO molecular beam splitting.

    Science.gov (United States)

    Cáceres, J O; Morato, M; González Ureña, A

    2006-12-28

    The interaction between a NO supersonic beam and a resonant radio frequency (RF) field is investigated using laser ionization coupled to imaging techniques. It is shown how the resonant interaction leads to a beam splitting of +/-0.2 degrees toward both positive and negative direction perpendicular to the beam propagation axis. This phenomenon is rationalized using a model based on molecular interferences produced by the action of the resonant RF electric field.

  3. The TANGO Project: Thorough ANalysis of radio-Galaxies Observations

    Science.gov (United States)

    Ocaña Flaquer, Breezy; Leon Tanne, Stephane; Combes, Francoise; Lim, Jeremy

    2010-05-01

    We present a sample of radio galaxies selected only on the basis of radio continuum emission and we confirm that these galaxies have lower molecular gas mass than other elliptical galaxies with different selection criteria.

  4. An RF frontend circuit design of a Compass and GPS dual-mode dual-channel image rejection radio receiver

    Science.gov (United States)

    Gong, Zhang; Honglin, Chen; Wei, Liu; Hanbing, Yang; Lijuan, Zhang; Xiangwei, Wang; Lei, Shi; Sijmg, Hu; Mingzhao, Wang; Zhuojian, Fu

    2013-08-01

    This paper introduces a fully integrated low power consumption radio receiver frontend circuit for a Compass (Beidou) and GPS dual mode dual channel system with 2.5 dB NF, 1.02 mm2 areas, and 8 mA of current in 0.18 μm TSMC CMOS process. Except for a few passive components for input matching, other components such as an off-chip low noise amplifier or a balun are not required. With a non-tunable passive image rejection filter, the receiver frontend can achieve around 60 dB gain and 34 dB image rejection.

  5. Radio-Tomographic Images of Post-midnight Equatorial Plasma Depletions

    Science.gov (United States)

    Hei, M. A.; Bernhardt, P. A.; Siefring, C. L.; Wilkens, M.; Huba, J. D.; Krall, J.; Valladares, C. E.; Heelis, R. A.; Hairston, M. R.; Coley, W. R.; Chau, J. L.

    2013-12-01

    For the first time, post-midnight equatorial plasma depletions (EPDs) have been imaged in the longitude-altitude plane using radio-tomography. High-resolution (~10 km × 10 km) electron-density reconstructions were created from total electron content (TEC) data using an array of receivers sited in Peru and the Multiplicative Algebraic Reconstruction Technique (MART) inversion algorithm. TEC data were obtained from the 150 and 400 MHz signals transmitted by the CERTO beacon on the C/NOFS satellite. In-situ electron density data from the C/NOFS CINDI instrument and electron density profiles from the UML Jicamarca ionosonde were used to generate an initial guess for the MART inversion, and also to constrain the inversion process. Observed EPDs had widths of 100-1000 km, spacings of 300-900 km, and often appeared 'pinched off' at the bottom. Well-developed EPDs appeared on an evening with a very small (4 m/s) Pre-Reversal-Enhancement (PRE), suggesting that postmidnight enhancements of the vertical plasma drift and/or seeding-induced uplifts (e.g. gravity waves) were responsible for driving the Rayleigh-Taylor Instability into the nonlinear regime on this night. On another night the Jicamarca ISR recorded postmidnight (~0230 LT) Eastward electric fields nearly twice as strong as the PRE fields seven hours earlier. These electric fields lifted the whole ionosphere, including embedded EPDs, over a longitude range ~14° wide. CINDI detected a dawn depletion in exactly the area where the reconstruction showed an uplifted EPD. Strong Equatorial Spread-F observed by the Jicamarca ionosonde during receiver observation times confirmed the presence of ionospheric irregularities.

  6. A Universal Continuum of Weight aleph

    CERN Document Server

    Dow, A; Dow, Alan; Hart, Klaas Pieter

    2001-01-01

    We prove that every continuum of weight aleph_1 is a continuous image of the Cech-Stone-remainder R^* of the real line. It follows that under CH the remainder of the half line [0,infty) is universal among the continua of weight c. We complement this result by showing that 1) under MA every continuum of weight less than c is a continuous image of R^* 2) in the Cohen model the long segment of length omega_2+1 is not a continuous image of R^*, and 3) PFA implies that I_u is not a continuous image of R^*, whenever u is a c-saturated ultrafilter.

  7. Detection and imaging of atmospheric radio flashes from cosmic ray air showers.

    Science.gov (United States)

    Falcke, H; Apel, W D; Badea, A F; Bähren, L; Bekk, K; Bercuci, A; Bertaina, M; Biermann, P L; Blümer, J; Bozdog, H; Brancus, I M; Buitink, S; Brüggemann, M; Buchholz, P; Butcher, H; Chiavassa, A; Daumiller, K; de Bruyn, A G; de Vos, C M; Di Pierro, F; Doll, P; Engel, R; Gemmeke, H; Ghia, P L; Glasstetter, R; Grupen, C; Haungs, A; Heck, D; Hörandel, J R; Horneffer, A; Huege, T; Kampert, K-H; Kant, G W; Klein, U; Kolotaev, Y; Koopman, Y; Krömer, O; Kuijpers, J; Lafebre, S; Maier, G; Mathes, H J; Mayer, H J; Milke, J; Mitrica, B; Morello, C; Navarra, G; Nehls, S; Nigl, A; Obenland, R; Oehlschläger, J; Ostapchenko, S; Over, S; Pepping, H J; Petcu, M; Petrovic, J; Plewnia, S; Rebel, H; Risse, A; Roth, M; Schieler, H; Schoonderbeek, G; Sima, O; Stümpert, M; Toma, G; Trinchero, G C; Ulrich, H; Valchierotti, S; van Buren, J; van Cappellen, W; Walkowiak, W; Weindl, A; Wijnholds, S; Wochele, J; Zabierowski, J; Zensus, J A; Zimmermann, D

    2005-05-19

    The nature of ultrahigh-energy cosmic rays (UHECRs) at energies >10(20) eV remains a mystery. They are likely to be of extragalactic origin, but should be absorbed within approximately 50 Mpc through interactions with the cosmic microwave background. As there are no sufficiently powerful accelerators within this distance from the Galaxy, explanations for UHECRs range from unusual astrophysical sources to exotic string physics. Also unclear is whether UHECRs consist of protons, heavy nuclei, neutrinos or gamma-rays. To resolve these questions, larger detectors with higher duty cycles and which combine multiple detection techniques are needed. Radio emission from UHECRs, on the other hand, is unaffected by attenuation, has a high duty cycle, gives calorimetric measurements and provides high directional accuracy. Here we report the detection of radio flashes from cosmic-ray air showers using low-cost digital radio receivers. We show that the radiation can be understood in terms of the geosynchrotron effect. Our results show that it should be possible to determine the nature and composition of UHECRs with combined radio and particle detectors, and to detect the ultrahigh-energy neutrinos expected from flavour mixing.

  8. Imaging correlated three-particle continuum states. Experiment and theory on the non-adiabatic projection of bound triatomic hydrogen into three separated atoms

    Energy Technology Data Exchange (ETDEWEB)

    Fechner, Peer Cornelis

    2015-07-21

    The central topic of this thesis is the experimental observation and the theoretical modeling of non-adiabatic three-body dissociation of H{sub 3} and D{sub 3} neutral triatomic hydrogen molecules. Our goal is to lend a meaning to the observed momentum vector correlation (MVC) of the three emerging ground state hydrogen atoms, for example H{sub 3}→H(1s)+H(1s)+H(1s), in terms of symmetries of the nuclear molecular wave function and of the non-adiabatic coupling which initiates this decay. In many experiments carried out over the years, a wealth of state specific MVCs was collected by different research groups. The MVCs are imaged in form of so-called Dalitz plots which show a rich structure of maxima and nodal lines, depending on the initial state of the triatomic hydrogen neutral. Theory was slow to catch up with experiment and only by this year, 2015, a general agreement was accomplished. Nevertheless, these models lack of an easy understanding of the underlying physics as many numerical calculations are involved. The theoretical model presented in this thesis follows a different approach which is more guided by the imaging character of our experiments. We concentrate on a rather qualitative treatment by limiting ourselves to the essential ingredients only. This proceeding contributes to giving a physical interpretation of the structures in the Dalitz plots in the following form: Three-particle coincident imaging offers a direct view of the emerging spatial continuum wave function of a predissociating triatomic molecule as it evolves from molecular spatial dimensions into the realm of independent free particles. This latter result is discussed in the context of the so-called Imaging Theorem, the second main part of this work. A third major part of this thesis pertains to obtaining molecular momentum wave functions in separated degrees-of-freedom via Fourier transformation. Even for triatomic hydrogen - the most simple polyatomic molecule - this is a challenging

  9. RADIO AND INFRARED-EMISSION FROM A [WC]-TYPE PLANETARY-NEBULA IN THE LMC

    NARCIS (Netherlands)

    ZIJLSTRA, AA; VANHOOF, PAM; CHAPMAN, JM; LOUP, C

    1994-01-01

    Radio continuum emission has been detected from a planetary nebula in the Large Magellanic Cloud: this is the first radio continuum detection for any planetary nebula outside our galaxy. The radio flux density is a factor of two lower than predicted from the HP flux. This could be due either to a

  10. Learning-Walk Continuum

    Science.gov (United States)

    Finch, Peter Dallas

    2010-01-01

    The continuum of learning walks can be viewed in stages with various dimensions including frequency, participants, purpose and the presence of an instructional framework within which the instructional practice is viewed. Steps in the continuum progress as the learning walks are conducted more frequently. One way to ensure this is accomplished is…

  11. Cost effective raspberry pi-based radio frequency identification tagging of mice suitable for automated in vivo imaging.

    Science.gov (United States)

    Bolaños, Federico; LeDue, Jeff M; Murphy, Timothy H

    2017-01-30

    Automation of animal experimentation improves consistency, reduces potential for error while decreasing animal stress and increasing well-being. Radio frequency identification (RFID) tagging can identify individual mice in group housing environments enabling animal-specific tracking of physiological parameters. We describe a simple protocol to radio frequency identification (RFID) tag and detect mice. RFID tags were injected sub-cutaneously after brief isoflurane anesthesia and do not require surgical steps such as suturing or incisions. We employ glass-encapsulated 125kHz tags that can be read within 30.2±2.4mm of the antenna. A raspberry pi single board computer and tag reader enable automated logging and cross platform support is possible through Python. We provide sample software written in Python to provide a flexible and cost effective system for logging the weights of multiple mice in relation to pre-defined targets. The sample software can serve as the basis of any behavioral or physiological task where users will need to identify and track specific animals. Recently, we have applied this system of tagging to automated mouse brain imaging within home-cages. We provide a cost effective solution employing open source software to facilitate adoption in applications such as automated imaging or tracking individual animal weights during tasks where food or water restriction is employed as motivation for a specific behavior. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Notes on continuum mechanics

    CERN Document Server

    Chaves, Eduardo W V

    2013-01-01

    This publication is aimed at students, teachers, and researchers of Continuum Mechanics and focused extensively on stating and developing Initial Boundary Value equations used to solve physical problems. With respect to notation, the tensorial, indicial and Voigt notations have been used indiscriminately.   The book is divided into twelve chapters with the following topics: Tensors, Continuum Kinematics, Stress, The Objectivity of Tensors, The Fundamental Equations of Continuum Mechanics, An Introduction to Constitutive Equations, Linear Elasticity, Hyperelasticity, Plasticity (small and large deformations), Thermoelasticity (small and large deformations), Damage Mechanics (small and large deformations), and An Introduction to Fluids. Moreover, the text is supplemented with over 280 figures, over 100 solved problems, and 130 references.

  13. An ALMA survey of submillimetre galaxies in the COSMOS field: The extent of the radio-emitting region revealed by 3 GHz imaging with the Very Large Array

    Science.gov (United States)

    Miettinen, O.; Novak, M.; Smolčić, V.; Delvecchio, I.; Aravena, M.; Brisbin, D.; Karim, A.; Murphy, E. J.; Schinnerer, E.; Albrecht, M.; Aussel, H.; Bertoldi, F.; Capak, P. L.; Casey, C. M.; Civano, F.; Hayward, C. C.; Herrera Ruiz, N.; Ilbert, O.; Jiang, C.; Laigle, C.; Le Fèvre, O.; Magnelli, B.; Marchesi, S.; McCracken, H. J.; Middelberg, E.; Muñoz Arancibia, A. M.; Navarrete, F.; Padilla, N. D.; Riechers, D. A.; Salvato, M.; Scott, K. S.; Sheth, K.; Tasca, L. A. M.; Bondi, M.; Zamorani, G.

    2017-06-01

    Context. The observed spatial scale of the radio continuum emission from star-forming galaxies can be used to investigate the spatial extent of active star formation, constrain the importance of cosmic-ray transport, and examine the effects of galaxy interactions. Aims: We determine the radio size distribution of a large sample of 152 submillimetre galaxies (SMGs) in the COSMOS field that were pre-selected at 1.1 mm, and later detected with the Atacama Large Millimetre/submillimetre Array (ALMA) in the observed-frame 1.3 mm dust continuum emission at a signal-to-noise ratio (S/N) of ≥5. Methods: We used the deep, subarcsecond-resolution (1σ = 2.3μJy beam-1;.̋75) centimetre radio continuum observations taken by the Karl G. Jansky Very Large Array (VLA)-COSMOS 3 GHz Large Project. Results: One hundred and fifteen of the 152 target SMGs (76% ± 7%) were found to have a 3 GHz counterpart (≥ 4.2σ), which renders the radio detection rate notably high. The median value of the deconvolved major axis full width at half maximum (FWHM) size at 3 GHz is derived to be 0.̋59 ± 0.̋05 , or 4.6 ± 0.4 kpc in physical units, where the median redshift of the sources is z = 2.23 ± 0.13 (23% are spectroscopic and 77% are photometric values). The radio sizes are roughly log-normally distributed, and they show no evolutionary trend with redshift, or difference between different galaxy morphologies. We also derived the spectral indices between 1.4 and 3 GHz, and 3 GHz brightness temperatures for the sources, and the median values were found to be α1.4 GHz3 GHz = -0.67 (Sν ∝ να) and TB = 12.6 ± 2 K. Three of the target SMGs, which are also detected with the Very Long Baseline Array (VLBA) at 1.4 GHz (AzTEC/C24b, 61, and 77a), show clearly higher brightness temperatures than the typical values, reaching TB(3 GHz) > 104.03 K for AzTEC/C61. Conclusions: The derived median radio spectral index agrees with a value expected for optically thin non-thermal synchrotron radiation

  14. Computational Continuum Mechanics

    CERN Document Server

    Shabana, Ahmed A

    2011-01-01

    This text presents the theory of continuum mechanics using computational methods. Ideal for students and researchers, the second edition features a new chapter on computational geometry and finite element analysis.

  15. Radio Detection of the Fermi-LAT Blind Search Millisecond Pulsar J1311-3430

    Science.gov (United States)

    Ray, P. S.; Ransom, S. M.; Cheung, C. C.; Giroletti, M.; Cognard, I.; Camilo, F.; Bhattacharyya, B.; Roy, J.; Romani, R. W.; Ferrara, E. C.; hide

    2013-01-01

    We report the detection of radio emission from PSR J1311.3430, the first millisecond pulsar (MSP) discovered in a blind search of Fermi Large Area Telescope (LAT) gamma-ray data. We detected radio pulsations at 2 GHz, visible for less than 10% of approximately 4.5 hr of observations using the Green Bank Telescope (GBT). Observations at 5 GHz with the GBT and at several lower frequencies with Parkes, Nan cay, and the Giant Metrewave Radio Telescope resulted in non-detections. We also report the faint detection of a steep spectrum continuum radio source (0.1 mJy at 5 GHz) in interferometric imaging observations with the Jansky Very Large Array. These detections demonstrate that PSR J1311.3430 is not radio quiet and provide additional evidence that radio-quiet MSPs are rare. The radio dispersion measure of 37.8 pc cm(exp -3) provides a distance estimate of 1.4 kpc for the system, yielding a gamma-ray efficiency of 30%, typical of LAT-detected MSPs. We see apparent excess delay in the radio pulses as the pulsar appears from eclipse and we speculate on possible mechanisms for the non-detections of the pulse at other orbital phases and observing frequencies.

  16. RADIO DETECTION OF THE FERMI-LAT BLIND SEARCH MILLISECOND PULSAR J1311-3430

    Energy Technology Data Exchange (ETDEWEB)

    Ray, P. S.; Wood, K. S. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Ransom, S. M. [National Radio Astronomy Observatory (NRAO), Charlottesville, VA 22903 (United States); Cheung, C. C. [National Academy of Sciences, Washington, DC 20001 (United States); Giroletti, M. [INAF Istituto di Radioastronomia, I-40129 Bologna (Italy); Cognard, I. [Laboratoire de Physique et Chimie de l' Environnement, LPCE UMR 6115 CNRS, F-45071 Orleans Cedex 02 (France); Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Bhattacharyya, B. [Inter-University Centre for Astronomy and Astrophysics, Pune 411 007 (India); Roy, J. [National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune 411 007 (India); Romani, R. W.; Kerr, M. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Ferrara, E. C. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Guillemot, L.; Kramer, M. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Johnston, S.; Keith, M. [CSIRO Astronomy and Space Science, Australia Telescope National Facility, Epping NSW 1710 (Australia); Pletsch, H. J. [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, D-30167 Hannover (Germany); Saz Parkinson, P. M., E-mail: Paul.Ray@nrl.navy.mil [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States)

    2013-01-20

    We report the detection of radio emission from PSR J1311-3430, the first millisecond pulsar (MSP) discovered in a blind search of Fermi Large Area Telescope (LAT) gamma-ray data. We detected radio pulsations at 2 GHz, visible for <10% of {approx}4.5 hr of observations using the Green Bank Telescope (GBT). Observations at 5 GHz with the GBT and at several lower frequencies with Parkes, Nancay, and the Giant Metrewave Radio Telescope resulted in non-detections. We also report the faint detection of a steep spectrum continuum radio source (0.1 mJy at 5 GHz) in interferometric imaging observations with the Jansky Very Large Array. These detections demonstrate that PSR J1311-3430 is not radio quiet and provide additional evidence that radio-quiet MSPs are rare. The radio dispersion measure of 37.8 pc cm{sup -3} provides a distance estimate of 1.4 kpc for the system, yielding a gamma-ray efficiency of 30%, typical of LAT-detected MSPs. We see apparent excess delay in the radio pulses as the pulsar appears from eclipse and we speculate on possible mechanisms for the non-detections of the pulse at other orbital phases and observing frequencies.

  17. Multifrequency radio observations of SNR J0536-6735 (N 59B with associated pulsar

    Directory of Open Access Journals (Sweden)

    Bozzetto L.M.

    2012-01-01

    Full Text Available We present a study of new Australian Telescope Compact Array (ATCA observations of supernova remnant, SNR J0536-6735. This remnant appears to follow a shell morphology with a diameter of D=36x29 pc (with 1 pc uncertainty in each direction. There is an embedded HII region on the northern limb of the remnant which made various analysis and measurements (such as flux density, spectral index and polarisation difficult. The radio-continuum emission followed the same structure as the optical emission, allowing for extent and flux density estimates at 20 cm. We estimate the surface brightness at 1 GHz of 2.55x10−21 Wm−2 Hz−1 sr−1 for the SNR. Also, we detect a distinctive radio-continuum point source which confirms the previous suggestion of this remnant being associated with pulsar wind nebula (PWN. The tail of this remnant is not seen in the radio-continuum images and is only seen in the optical and X-ray images.

  18. The LOFAR radio environment

    NARCIS (Netherlands)

    Offringa, A. R.; de Bruyn, A. G.; Zaroubi, S.; van Diepen, G.; Martinez-Ruby, O.; Labropoulos, P.; Brentjens, M. A.; Ciardi, B.; Daiboo, S.; Harker, G.; Jelic, V.; Kazemi, S.; Koopmans, L. V. E.; Pandey, V. N.; Pizzo, R. F.; Schaye, J.; Vedantham, H.; Veligatla, V.; Wijnholds, S. J.; Yatawatta, S.; Zarka, P.; Alexov, A.; Anderson, J.; Asgekar, A.; Avruch, M.; Beck, R.; Bell, M.; Bell, M. R.; Bentum, M.; Bernardi, G.; Best, P.; Birzan, L.; Bonafede, A.; Breitling, F.; Broderick, J. W.; Brueggen, M.; Butcher, H.; Conway, J.; de Vos, M.; Dettmar, R. J.; Eisloeffel, J.; Falcke, H.; Fender, R.; Frieswijk, W.; Gerbers, M.; Griessmeier, J. M.; Gunst, A. W.; Hassall, T. E.; Heald, G.; Hessels, J.; Hoeft, M.; Horneffer, A.; Karastergiou, A.; Kondratiev, V.; Koopman, Y.; Kuniyoshi, M.; Kuper, G.; Maat, P.; Mann, G.; McKean, J.; Meulman, H.; Mevius, M.; Mol, J.D.; Nijboer, R.; Noordam, J.; Norden, M.; Paas, H.; Pandey, M.; Pizzo, R.; Polatidis, A.; Rafferty, D.; Rawlings, S.; Reich, W.; Roettgering, H. J. A.; Schoenmakers, A. P.; Sluman, J.; Smirnov, O.; Sobey, C.; Stappers, B.; Steinmetz, M.; Swinbank, J.; Tagger, M.; Tang, Y.; Tasse, C.; van Ardenne, A.; van Cappellen, W.; van Duin, A. P.; van Haarlem, M.; van Leeuwen, J.; van Weeren, R. J.; Vermeulen, R.; Vocks, C.; Wijers, R. A. M. J.; Wise, M.; Wucknitz, O.; Mellema, G.

    Aims. This paper discusses the spectral occupancy for performing radio astronomy with the Low-Frequency Array (LOFAR), with a focus on imaging observations. Methods. We have analysed the radio-frequency interference (RFI) situation in two 24-h surveys with Dutch LOFAR stations, covering 30-78 MHz

  19. Apoptosis imaging studies in various animal models using radio-iodinated peptide.

    Science.gov (United States)

    Kwak, Wonjung; Ha, Yeong Su; Soni, Nisarg; Lee, Woonghee; Park, Se-Il; Ahn, Heesu; An, Gwang Il; Kim, In-San; Lee, Byung-Heon; Yoo, Jeongsoo

    2015-01-01

    Apoptosis has a role in many medical disorders and treatments; hence, its non-invasive evaluation is one of the most riveting research topics. Currently annexin V is used as gold standard for imaging apoptosis. However, several drawbacks, including high background, slow body clearance, make it a suboptimum marker for apoptosis imaging. In this study, we radiolabeled the recently identified histone H1 targeting peptide (ApoPep-1) and evaluated its potential as a new apoptosis imaging agent in various animal models. ApoPep-1 (CQRPPR) was synthesized, and an extra tyrosine residue was added to its N-terminal end for radiolabeling. This peptide was radiolabeled with (124)I and (131)I and was tested for its serum stability. Surgery- and drug-induced apoptotic rat models were prepared for apoptosis evaluation, and PET imaging was performed. Doxorubicin was used for xenograft tumor treatment in mice, and the induced apoptosis was studied. Tumor metabolism and proliferation were assessed by [(18)F]FDG and [(18)F]FLT PET imaging and compared with ApoPep-1 after doxorubicin treatment. The peptide was radiolabeled at high purity, and it showed reasonably good stability in serum. Cell death was easily imaged by radiolabeled ApoPep-1 in an ischemia surgery model. And, liver apoptosis was more clearly identified by ApoPep-1 rather than [(124)I]annexin V in cycloheximide-treated models. Three doxorubicin doses inhibited tumor growth, which was evaluated by 30-40% decreases of [(18)F]FDG and [(18)F]FLT PET uptake in the tumor area. However, ApoPep-1 demonstrated more than 200% increase in tumor uptake after chemotherapy, while annexin V did not show any meaningful uptake in the tumor compared with the background. Biodistribution data were also in good agreement with the microPET imaging results. All of the experimental data clearly demonstrated high potential of the radiolabeled ApoPep-1 for in vivo apoptosis imaging.

  20. The continuum in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Liotta, R.J. [Royal Inst. of Tech. Stockholm (Sweden). Dept. of Solid State Electronics

    1995-11-01

    The Green function formalism is used to extend the standard (shell-model) treatment of bound states to processes that occur in the continuum part of nuclear spectra. The Berggren and Mittag-Leffler expansions are introduced and analysed. Applications to single-particle and particle-hole resonances are performed. Giant resonances are studied within the framework of the continuum RPA. In all cases it is found that the expansions agree well with the exact calculation. The mechanisms that induce the clustering of nucleons in nuclei are analysed and the corresponding decay processes are discussed in detail. (orig.)

  1. Introduction to continuum mechanics

    CERN Document Server

    Lai, W Michael; Rubin, David

    1996-01-01

    Introduction to Continuum Mechanics is a recently updated and revised text which is perfect for either introductory courses in an undergraduate engineering curriculum or for a beginning graduate course.Continuum Mechanics studies the response of materials to different loading conditions. The concept of tensors is introduced through the idea of linear transformation in a self-contained chapter, and the interrelation of direct notation, indicial notation, and matrix operations is clearly presented. A wide range of idealized materials are considered through simple static and dynamic problems, a

  2. Fundamentals of continuum mechanics

    CERN Document Server

    Rudnicki, John W

    2014-01-01

    A concise introductory course text on continuum mechanics Fundamentals of Continuum Mechanics focuses on the fundamentals of the subject and provides the background for formulation of numerical methods for large deformations and a wide range of material behaviours. It aims to provide the foundations for further study, not just of these subjects, but also the formulations for much more complex material behaviour and their implementation computationally.  This book is divided into 5 parts, covering mathematical preliminaries, stress, motion and deformation, balance of mass, momentum and energ

  3. Radio Journalism.

    Science.gov (United States)

    Bittner, John R.; Bittner, Denise A.

    This book, a how-to-do-it guide for the novice and the professional alike, deals with several aspects of radio journalism: producing documentaries, preparing and announcing radio news, ethics and responsibility, regulation of radio journalism, and careers. It traces the history and growth of radio news, shows its impact on the public, and…

  4. Subarcminute Resolution Imaging of Radio Sources at 74 MHz with the Very Large Array

    National Research Council Canada - National Science Library

    Kassim, N. E; Perley, R. A; Erickson, W. C; Dwarakanath, K. S

    1993-01-01

    .... Although the system is of low efficiency, it works well for imaging strong sources (S ̃ > 20O Jy) on long baselines (> 5 km) since self-calibration has sufficient signal to noise to remove phase errors on the short time scales...

  5. High-resolution emission-line imaging of Seyfert galaxies. I - Observations. II - Evidence for anisotropic ionizing radiation

    Science.gov (United States)

    Haniff, Christopher A.; Wilson, Andrew S.; Ward, Martin J.

    1988-01-01

    A CCD direct imaging survey of 11 Seyfert galaxies with a mean seeing of 1.3 arcsec FWHM is presented. It is found that the major axes and spatial scales of the circumnuclear emission-line gas are very similar to those of the radio continuum sources. In the second part, this close connection between thermal and relativistic gases is examined. A scenario is proposed in which the radio jets and plasmoids shock, accelerate, and compress ambient and entrained gas, with the dominant source of ionization being the nonstellar nuclear UV continuum.

  6. The MUPPLE competence continuum

    NARCIS (Netherlands)

    Wild, Joanna; Wild, Fridolin; Kalz, Marco; Specht, Marcus; Hofer, Margit

    2009-01-01

    Wild, J., Wild, F., Kalz, M., Specht, M., & Hofer, M. (2009). The MUPPLE competence continuum. In F. Wild, M. Kalz, M. Palmér & D. Müller (Eds.), Proceedings of 2nd Workshop Mash-Up Personal Learning Envrionments (MUPPLE'09). Workshop in conjunction with 4th European Conference on Technology

  7. Numerical continuum mechanics

    CERN Document Server

    Kukudzhanov, Vladimir N

    2013-01-01

    This work focuses on computational methods in continuum thermomechanics. The text is based on the author's lectures, which ensures a didactical and coherent buildup.The main emphasis is put on the presentation of ideas and qualitative considerations, illustrated by specific examples and applications. Conditions and explanations that are essential for the practical application of methods are discussed thoroughly.

  8. The Continuum of Listening

    Science.gov (United States)

    Rud, A. G.; Garrison, Jim

    2007-01-01

    The distinction between "apophatic" and "cataphatic" listening is defined and analyzed. "Apophatic" listening is more or less devoid of cognitivist claims, whereas "cataphatic" listening involves cognition and questioning. Many of the papers in this volume are discussed along the continuum determined by these two types of listening.…

  9. Automated optical inspection and image analysis of superconducting radio-frequency cavities

    Energy Technology Data Exchange (ETDEWEB)

    Wenskat, Marc

    2017-04-15

    The inner surface of superconducting cavities plays a crucial role to achieve highest accelerating fields and low losses. For an investigation of this inner surface of more than 100 cavities within the cavity fabrication for the European XFEL and the ILC HiGrade Research Project, an optical inspection robot OBACHT was constructed. To analyze up to 2325 images per cavity, an image processing and analysis code was developed and new variables to describe the cavity surface were obtained. The accuracy of this code is up to 97% and the PPV 99% within the resolution of 15.63 μm. The optical obtained surface roughness is in agreement with standard profilometric methods. The image analysis algorithm identified and quantified vendor specific fabrication properties as the electron beam welding speed and the different surface roughness due to the different chemical treatments. In addition, a correlation of ρ=-0.93 with a significance of 6σ between an obtained surface variable and the maximal accelerating field was found.

  10. Advancements of labelled radio-pharmaceutics imaging with the PIM-MPGD

    Science.gov (United States)

    Donnard, J.; Arlicot, N.; Berny, R.; Carduner, H.; Leray, P.; Morteau, E.; Servagent, N.; Thers, D.

    2009-11-01

    The Beta autoradiography is widely used in pharmacology or in biological fields to study the response of an organism to a certain kind of molecule. The image of the distribution is processed by studying the concentration of the radioactivity into different organs. We report on the development of an integrated apparatus based on a PIM device (Parallel Ionization Multiplier) able to process the image of 10 microscope slides at the same time over an area of 18*18 cm2. Thanks to a vacuum pump and a regulation gas circuit, 5 minutes is sufficient to begin an acquisition. All the electronics and the gas distribution are included in the structure leading to a transportable device. Special software has been developed to process data in real time with image visualization. Biological samples can be labelled with β emitters of low energy like 3H/14C or Auger electrons of 125I/99mTc. The measured spatial resolution is 30 μm in 3H and the trigger and the charge rate are constant over more than 6 days of acquisition showing good stability of the device. Moreover, collaboration with doctors and biologists of INSERM (National Institute for Medical Research in France) has started in order to demonstrate that MPGD's can be easily proposed outside a physics laboratory.

  11. Automated optical inspection and image analysis of superconducting radio-frequency cavities

    Science.gov (United States)

    Wenskat, M.

    2017-05-01

    The inner surface of superconducting cavities plays a crucial role to achieve highest accelerating fields and low losses. For an investigation of this inner surface of more than 100 cavities within the cavity fabrication for the European XFEL and the ILC HiGrade Research Project, an optical inspection robot OBACHT was constructed. To analyze up to 2325 images per cavity, an image processing and analysis code was developed and new variables to describe the cavity surface were obtained. The accuracy of this code is up to 97 % and the positive predictive value (PPV) 99 % within the resolution of 15.63 μm. The optical obtained surface roughness is in agreement with standard profilometric methods. The image analysis algorithm identified and quantified vendor specific fabrication properties as the electron beam welding speed and the different surface roughness due to the different chemical treatments. In addition, a correlation of ρ = -0.93 with a significance of 6 σ between an obtained surface variable and the maximal accelerating field was found.

  12. High Fidelity Solar and Heliospheric Imaging at Low Radio Frequencies: Progress and Future Prospects

    Science.gov (United States)

    Lonsdale, C.; Oberoi, D.; Kozarev, K. A.; Morgan, J.; Benkevitch, L. V.; Erickson, P. J.; Crowley, M.; McCauley, P.; Cairns, I.

    2016-12-01

    The latest generation of low frequency interferometric arrays is revolutionizing solar and heliospheric imaging capabilities. Via a combination of large numbers of independent antennas and greatly increased computing capacity, sufficient information can now be gathered and processed to generate high fidelity images at high time and frequency resolution. For the first time, it is possible to reconstruct spatially, temporally and spectrally complex solar emissions in detail, to measure interplanetary scintillation for many sources simultaneously over wide fields of view, and to track heliospheric disturbances via rapidly evolving propagation effects. These new and rapidly improving capabilities will help to address a range of long-standing scientific questions in the field. We review the current state of the art of low frequency imaging instruments, with particular emphasis on, and examples from, the Murchison Widefield Array (MWA). The limitations and challenges of such arrays are explored, and the prospects for next-generation ground and space based arrays yielding additional major advances in capability are reviewed.

  13. VLA Observations of a Complete Sample of Radio Loud Quasars between redshifts 2.5 and 5.28: I. high-redshift sample summary and the radio images

    OpenAIRE

    Gobeille, Doug B.; Wardle, John F. C.; Cheung, C. C.

    2014-01-01

    We present high resolution (arcsecond or better) observations made with the Karl G. Jansky Very Large Array of 123 radio-loud quasars with redshifts in the range $2.5 \\leq z \\leq 5.28$ that form a complete flux limited sample ($\\geq 70$ mJy at 1.4 GHz or 5 GHz). Where possible, we used previous high resolution VLA observations (mainly A array at 1.4, 5 and 8 GHz) from the NRAO archive and re-imaged them (43 sources). For the remainder, new observations were made in the A array at 1.4 and 5 GH...

  14. Restaging of locally advanced carcinoma of the rectum with MR imaging after preoperative radio-chemotherapy plus regional hyperthermia

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, K.T.; Wust, P.; Stroszczynski, C.; Felix, R. [Dept. of Radiology and Radiation Oncology, Campus Virchow-Klinikum, Charite (Germany); Rau, B.; Huenerbein, M. [Div. of Surgery and Surgical Oncology, Robert-Roessle Hospital and Tumor Inst., Humboldt Univ. Berlin (Germany); Schneider, U. [Inst. of Pathology, Campus Buch, Charite, Robert-Roessle Hospital and Tumor Inst., Humboldt Univ. Berlin (Germany)

    2002-07-01

    Background: The restaging accuracy of MR imaging in advanced primary rectal carcinoma after preoperative radiochemotherapy and regional hyperthermia was evaluated and compared with the histopathologically verified degree of tumor remission after a course of radio-chemo-thermotherapy. Patients and Methods: 35 patients with primary rectal carcinoma (uT3/uT4) underwent MRI using a surface coil 4-6 weeks after radiochemotherapy (n=35), regional hyperthermia (n=23), and before curative surgery. We defined as gold standard for the remission status the comparison of pretherapeutic endosonography with the histopathology of the resected specimen. Results: T category was correctly restaged after preoperative treatment in only 19 (54%) of 35 patients. Nine of 20 responders were overstaged and seven of 15 non-responders were understaged. Concurrently, the N category was correctly restaged in 19 (54%) of 35 patients (twelve responders and seven non-responders). Overstaging occurred in four responders and two non-responders, understaging occurred in four responders and six non-responders. Conclusions: MRI proved independent of the response status as not suitable to restage locally advanced rectal carcinoma after preoperative radiochemotherapy despite optimized imaging technique and spatial resolution. Basically, imaging the morphology of a tumor cannot clearly differentiate between vital and devitalized tissue after a treatment. Functional imaging such as PET (positron emission tomography) appears more feasible for restaging after radio-chemo-thermotherapy. (orig.) [German] Hintergrund: Die Genauigkeit der Stadienbestimmung mittels MR-Bildgebung wurde bei primaer fortgeschrittenen Rektumkarzinomen nach praeoperativer Radiochemotherapie und regionaler Hyperthermie gepueft und mit der histopathologisch ermittelten Tumorremission nach praeoperativer Behandlung verglichen. Patienten und Methode: 35 Patienten mit primaeren Rektumkarzinomen (uT3/uT4) wurden MR-tomographisch mittels

  15. Nonlocal continuum field theories

    CERN Document Server

    2002-01-01

    Nonlocal continuum field theories are concerned with material bodies whose behavior at any interior point depends on the state of all other points in the body -- rather than only on an effective field resulting from these points -- in addition to its own state and the state of some calculable external field. Nonlocal field theory extends classical field theory by describing the responses of points within the medium by functionals rather than functions (the "constitutive relations" of classical field theory). Such considerations are already well known in solid-state physics, where the nonlocal interactions between the atoms are prevalent in determining the properties of the material. The tools developed for crystalline materials, however, do not lend themselves to analyzing amorphous materials, or materials in which imperfections are a major part of the structure. Nonlocal continuum theories, by contrast, can describe these materials faithfully at scales down to the lattice parameter. This book presents a unif...

  16. Continuum mechanics for engineers

    CERN Document Server

    Mase, G Thomas; Mase, George E

    2009-01-01

    Continuum TheoryContinuum MechanicsStarting OverNotationEssential MathematicsScalars, Vectors and Cartesian TensorsTensor Algebra in Symbolic Notation - Summation ConventionIndicial NotationMatrices and DeterminantsTransformations of Cartesian TensorsPrincipal Values and Principal DirectionsTensor Fields, Tensor CalculusIntegral Theorems of Gauss and StokesStress PrinciplesBody and Surface Forces, Mass DensityCauchy Stress PrincipleThe Stress TensorForce and Moment Equilibrium; Stress Tensor SymmetryStress Transformation LawsPrincipal Stresses; Principal Stress DirectionsMaximum and Minimum Stress ValuesMohr's Circles For Stress Plane StressDeviator and Spherical Stress StatesOctahedral Shear StressKinematics of Deformation and MotionParticles, Configurations, Deformations and MotionMaterial and Spatial CoordinatesLangrangian and Eulerian DescriptionsThe Displacement FieldThe Material DerivativeDeformation Gradients, Finite Strain TensorsInfinitesimal Deformation TheoryCompatibility EquationsStretch RatiosRot...

  17. Radio Selection of the Most Distant Galaxy Clusters

    Science.gov (United States)

    Daddi, E.; Jin, S.; Strazzullo, V.; Sargent, M. T.; Wang, T.; Ferrari, C.; Schinnerer, E.; Smolčić, V.; Calabró, A.; Coogan, R.; Delhaize, J.; Delvecchio, I.; Elbaz, D.; Gobat, R.; Gu, Q.; Liu, D.; Novak, M.; Valentino, F.

    2017-09-01

    We show that the most distant X-ray-detected cluster known to date, Cl J1001 at {z}{spec}=2.506, hosts a strong overdensity of radio sources. Six of them are individually detected (within 10\\prime\\prime ) in deep 0\\buildrel{\\prime\\prime}\\over{.} 75 resolution VLA 3 GHz imaging, with {S}3{GHz}> 8 μ {Jy}. Of the six, an active galactic nucleus (AGN) likely affects the radio emission in two galaxies, while star formation is the dominant source powering the remaining four. We searched for cluster candidates over the full COSMOS 2 deg2 field using radio-detected 3 GHz sources and looking for peaks in {{{Σ }}}5 density maps. Cl J1001 is the strongest overdensity by far with > 10σ , with a simple {z}{phot}> 1.5 preselection. A cruder photometric rejection of zgeneration of forming galaxy clusters. In these remarkable structures, widespread star formation and AGN activity of massive galaxy cluster members, residing within the inner cluster core, will ultimately lead to radio continuum as one of the most effective means for their identification, with detection rates expected in the ballpark of 0.1-1 per square degree at z≳ 2.5. Samples of hundreds such high-redshift clusters could potentially constrain cosmological parameters and test cluster and galaxy formation models.

  18. Imaging of spatial distributions of the millimeter wave intensity by using the Visible Continuum Radiation from a discharge in a Cs-Xe mixture. Part II: Demonstration of application capabilities of the technique

    Science.gov (United States)

    Gitlin, M. S.; Glyavin, M. Yu.; Fedotov, A. E.; Tsvetkov, A. I.

    2017-07-01

    The paper presents the second part of the review on a high-sensitive technique for time-resolved imaging and measurements of the 2D intensity profiles of millimeter-wave radiation by means of Visible Continuum Radiation emitted by the positive column of a medium-pressure Cs-Xe DC Discharge (VCRD method). The first part of the review was focused on the operating principles and fundamentals of this new technique [Plasma Phys. Rep. 43, 253 (2017)]. The second part of the review focuses on experiments demonstrating application of this imaging technique to measure the parameters of radiation at the output of moderate-power millimeter-wave sources. In particular, the output waveguide mode of a moderate-power W-band gyrotron with a pulsed magnetic field was identified and the relative powers of some spurious modes at the outputs of this gyrotron and a pulsed D-band orotron were evaluated. The paper also reviews applications of the VCRD technique for real-time imaging and nondestructive testing with a frame rate of higher than 10 fps by using millimeter waves. Shadow projection images of objects opaque and transparent for millimeter waves have been obtained using pulsed watt-scale millimeter waves for object illumination. Near video frame rate millimeter-wave shadowgraphy has been demonstrated. It is shown that this technique can be used for single-shot screening (including detection of concealed objects) and time-resolved imaging of time-dependent processes.

  19. Radio Mariackie

    OpenAIRE

    Tytko, Marek Mariusz

    1993-01-01

    Tekst dotyczy początków katolickiego Radia Mariackiego w Krakowie w 1993 r. The text concerns the begining of the Mariackie Radio [The Mariackie Broadcasting, the Maria's Radio Station, the Maria's Broadcasting, the Maria's Radio) in Cracow 1993.

  20. Introduction to continuum mechanics

    CERN Document Server

    Rubin, David; Lai, W Michael

    1994-01-01

    Continuum mechanics studies the response of materials to different loading conditions. The concept of tensors is introduced through the idea of linear transformation in a self-contained chapter, and the interrelation of direct notation, indicial notation and matrix operations is clearly presented. A wide range of idealized materials are considered through simple static and dynamic problems, and the book contains an abundance of illustrative examples and problems, many with solutions. Through the addition of more advanced material (solution of classical elasticity problems, constitutive e

  1. Digital Low Frequency Radio Camera

    Science.gov (United States)

    Fullekrug, M.; Mezentsev, A.; Soula, S.; van der Velde, O.; Poupeney, J.; Sudre, C.; Gaffet, S.; Pincon, J.

    2012-04-01

    This contribution reports the design, realization and operation of a novel digital low frequency radio camera towards an exploration of the Earth's electromagnetic environment with particular emphasis on lightning discharges and subsequent atmospheric effects such as transient luminous events. The design of the digital low frequency radio camera is based on the idea of radio interferometry with a network of radio receivers which are separated by spatial baselines comparable to the wavelength of the observed radio waves, i.e., ~1-100 km which corresponds to a frequency range from ~3-300 kHz. The key parameter towards the realization of the radio interferometer is the frequency dependent slowness of the radio waves within the Earth's atmosphere with respect to the speed of light in vacuum. This slowness is measured with the radio interferometer by using well documented radio transmitters. The digital low frequency radio camera can be operated in different modes. In the imaging mode, still photographs show maps of the low frequency radio sky. In the video mode, movies show the dynamics of the low frequency radio sky. The exposure time of the photograhps, the frame rate of the video, and the radio frequency of interest can be adjusted by the observer. Alternatively, the digital radio camera can be used in the monitoring mode, where a particular area of the sky is observed continuously. The first application of the digital low frequency radio camera is to characterize the electromagnetic energy emanating from sprite producing lightning discharges, but it is expected that it can also be used to identify and investigate numerous other radio sources of the Earth's electromagnetic environment.

  2. High resolution radio-imager for biology and micro-dosimetry; Radio-imagerie haute resolution appliquee a la biologie et a la micro-dosimetrie

    Energy Technology Data Exchange (ETDEWEB)

    Aubineau-Laniece, I.; Charon, Y.; Laniece, P.; Mastrippolito, R.; Pinot, L.; Valentin, L. [Groupe I.P.B., Experimental Research Division, Inst. de Physique Nucleaire, Paris-11 Univ., 91 - Orsay (France)

    1999-11-01

    We have developed a self triggered intensified CCD (STIC) for real time high spatial resolution a and b imaging. This device is, in particular, of great interest for quantitative autoradiography of radiolabeled biochemical species with low level activity. (authors) 2 figs.

  3. The Double–Double Radio Galaxy 3C293

    Indian Academy of Sciences (India)

    We present the results of radio continuum observations at frequencies ranging from ∼ 150–5000 MHz of the misaligned double–double radio galaxy (DDRG) 3C293 (J1352+3126) using the GMRT and the VLA, and estimate the time-scale of interruption of jet activity to be less than ∼ 0.1 Myr.

  4. Imaging of spatial distributions of the millimeter wave intensity by using visible continuum radiation from a discharge in a Cs-Xe mixture. Part I: Review of the method and its fundamentals

    Science.gov (United States)

    Gitlin, M. S.

    2017-02-01

    The first part of the review is presented which is dedicated to the time-resolved method of imaging and measuring the spatial distribution of the intensity of millimeter waves by using visible continuum (VC) emitted by the positive column (PC) of a dc discharge in a mixture of cesium vapor with xenon. The review focuses on the operating principles, fundamentals, and applications of this new technique. The design of the discharge tube and experimental setup used to create a wide homogeneous plasma slab with the help of the Cs-Xe discharge at a gas pressure of 45 Torr are described. The millimeter-wave effects on the plasma slab are studied experimentally. The mechanism of microwave-induced variations in the VC brightness and the causes of violation of the local relation between the VC brightness and the intensity of millimeter waves are discussed. Experiments on the imaging of the field patterns of horn antennas and quasi-optical beams demonstrate that this technique can be used for good-quality imaging of millimeter-wave beams in the entire millimeter-wavelength band. The method has a microsecond temporal resolution and a spatial resolution of about 2 mm. Energy sensitivities of about 10 μJ/cm2 in the Ka-band and about 200 μJ/cm2 in the D-band have been demonstrated.

  5. Imaging of spatial distributions of the millimeter wave intensity by using visible continuum radiation from a discharge in a Cs–Xe mixture. Part I: Review of the method and its fundamentals

    Energy Technology Data Exchange (ETDEWEB)

    Gitlin, M. S., E-mail: gitlin@appl.sci-nnov.ru [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation)

    2017-02-15

    The first part of the review is presented which is dedicated to the time-resolved method of imaging and measuring the spatial distribution of the intensity of millimeter waves by using visible continuum (VC) emitted by the positive column (PC) of a dc discharge in a mixture of cesium vapor with xenon. The review focuses on the operating principles, fundamentals, and applications of this new technique. The design of the discharge tube and experimental setup used to create a wide homogeneous plasma slab with the help of the Cs–Xe discharge at a gas pressure of 45 Torr are described. The millimeter-wave effects on the plasma slab are studied experimentally. The mechanism of microwave-induced variations in the VC brightness and the causes of violation of the local relation between the VC brightness and the intensity of millimeter waves are discussed. Experiments on the imaging of the field patterns of horn antennas and quasi-optical beams demonstrate that this technique can be used for good-quality imaging of millimeter-wave beams in the entire millimeter-wavelength band. The method has a microsecond temporal resolution and a spatial resolution of about 2 mm. Energy sensitivities of about 10 μJ/cm{sup 2} in the Ka-band and about 200 μJ/cm{sup 2} in the D-band have been demonstrated.

  6. Modeling of radio-frequency induced currents on lead wires during MR imaging using a modified transmission line method.

    Science.gov (United States)

    Acikel, Volkan; Atalar, Ergin

    2011-12-01

    Metallic implants may cause serious tissue heating during magnetic resonance (MR) imaging. This heating occurs due to the induced currents caused by the radio-frequency (RF) field. Much work has been done to date to understand the relationship between the RF field and the induced currents. Most of these studies, however, were based purely on experimental or numerical methods. This study has three main purposes: (1) to define the RF heating properties of an implant lead using two parameters; (2) to develop an analytical formulation that directly explains the relationship between RF fields and induced currents; and (3) to form a basis for analysis of complex cases. In this study, a lumped element model of the transmission line was modified to model leads of implants inside the body. Using this model, leads are defined using two parameters: impedance per unit length, Z, and effective wavenumber along the lead, k(t). These two parameters were obtained by using methods that are similar to the transmission line theory. As long as these parameters are known for a lead, currents induced in the lead can be obtained no matter how complex the lead geometry is. The currents induced in bare wire, lossy wire, and insulated wire were calculated using this new method which is called the modified transmission line method or MoTLiM. First, the calculated induced currents under uniform electric field distribution were solved and compared with method-of-moments (MoM) calculations. In addition, MoTLiM results were compared with those of phantom experiments. For experimental verification, the flip angle distortion due to the induced currents was used. The flip angle distribution around a wire was both measured by using flip angle imaging methods and calculated using current distribution obtained from the MoTLiM. Finally, these results were compared and an error analysis was carried out. Bare perfect electric, bare lossy, and insulated perfect electric conductor wires under uniform and

  7. DID INSTAGRAM KILLED THE MYSTERY OF RADIO? USE OF INSTAGRAM IN TURKISH RADIO STATIONS AND RADIO HOSTS

    Directory of Open Access Journals (Sweden)

    Michalis Kuyucu

    2016-04-01

    Full Text Available Turning voice into imagination, radio translated imagination into reality with social media. The radio audience imagined there were people inside the receiver and wondered what kind of people those people were. This convergence between radio and the new media ensured realization of this imagination. The new media established communication between the people inside that radio receiver and the audience. Social media platform Instagram is the latest step in turning the radio from an image into reality. Are radio stations revealing themselves by throwing away the mystery via Instagram or do they still remain mysterious? The purpose of this study is to carry out a research directed at Instagram use of radio stations in Turkey and makes observations with regards to the existence of radio medium in Instagram. The existence of ten Turkish radio stations with the highest ratings among radio stations and ten radio hosts in Instagram was studied within this scope. The messages shared by the radio stations and hosts on their Instagram accounts were examined and an analysis was made intended at use of Instagram through these messages. The Instagram account activities of radio stations between 01 June – 31 December 2015 were reviewed within this scope and Instagram’s contribution to public relations activities of radio stations carried out by social media was scrutinized. The question “Did Instagram unveiled the mystery of radio?” was discussed and how radio is revealed by means of Instagram was underlined in this study.

  8. GMRT Low Radio Frequency Study of the Wolf Rayet Galaxy NGC ...

    Indian Academy of Sciences (India)

    In this paper, we present the first low frequency (< 1.4 GHz) radio continuum study of a Wolf Rayet galaxy NGC 4214 using the Giant Meterwave Radio Telescope (GMRT). We detect diffuse extended emission from the galaxy disk at 325 MHz and find that the radio emission closely follows the ultraviolet emission mapped by ...

  9. GMRT Low Radio Frequency Study of the Wolf Rayet Galaxy NGC ...

    Indian Academy of Sciences (India)

    Abstract. In this paper, we present the first low frequency (< 1.4 GHz) radio continuum study of a Wolf Rayet galaxy NGC 4214 using the. Giant Meterwave Radio Telescope (GMRT). We detect diffuse extended emission from the galaxy disk at 325 MHz and find that the radio emis- sion closely follows the ultraviolet emission ...

  10. Discrimination between weaned and unweaned Atlantic cod (Gadus morhua in capture-based aquaculture (CBA by X-ray imaging and radio-frequency metal detector.

    Directory of Open Access Journals (Sweden)

    Ekrem Misimi

    Full Text Available The aim of this study was to investigate the feasibility of two detection methods for use in discrimination and sorting of adult Atlantic cod (about 2 kg in the small scale capture-based aquaculture (CBA. Presently, there is no established method for discrimination of weaned and unweaned cod in CBA. Generally, 60-70% of the wild-caught cod in the CBA are weaned into commercial dry feed. To increase profitability for the fish farmers, unweaned cod must be separated from the stock, meaning the fish must be sorted into two groups - unweaned and weaned from moist feed. The challenges with handling of large numbers of fish in cages, defined the limits of the applied technology. As a result, a working model was established, focusing on implementing different marking materials added to the fish feed, and different technology for detecting the feed presence in the fish gut. X-ray imaging in two modes (planar and dual energy band and sensitive radio-frequency metal detection were the detection methods that were chosen for the investigations. Both methods were tested in laboratory conditions using dead fish with marked feed inserted into the gut cavity. In particular, the sensitive radio-frequency metal detection method with carbonyl powder showed very promising results in detection of marked feed. Results show also that Dual energy band X-ray imaging may have potential for prediction of fat content in the feed. Based on the investigations it can be concluded that both X-ray imaging and sensitive radio-frequency metal detector technology have the potential for detecting cod having consumed marked feed. These are all technologies that may be adapted to large scale handling of fish from fish cages. Thus, it may be possible to discriminate between unweaned and weaned cod in a large scale grading situation. Based on the results of this study, a suggestion for evaluation of concept for in-situ sorting system is presented.

  11. Discrimination between Weaned and Unweaned Atlantic Cod (Gadus morhua) in Capture-Based Aquaculture (CBA) by X-Ray Imaging and Radio-Frequency Metal Detector

    Science.gov (United States)

    Misimi, Ekrem; Martinsen, Svein; Mathiassen, John Reidar; Erikson, Ulf

    2014-01-01

    The aim of this study was to investigate the feasibility of two detection methods for use in discrimination and sorting of adult Atlantic cod (about 2 kg) in the small scale capture-based aquaculture (CBA). Presently, there is no established method for discrimination of weaned and unweaned cod in CBA. Generally, 60–70% of the wild-caught cod in the CBA are weaned into commercial dry feed. To increase profitability for the fish farmers, unweaned cod must be separated from the stock, meaning the fish must be sorted into two groups – unweaned and weaned from moist feed. The challenges with handling of large numbers of fish in cages, defined the limits of the applied technology. As a result, a working model was established, focusing on implementing different marking materials added to the fish feed, and different technology for detecting the feed presence in the fish gut. X-ray imaging in two modes (planar and dual energy band) and sensitive radio-frequency metal detection were the detection methods that were chosen for the investigations. Both methods were tested in laboratory conditions using dead fish with marked feed inserted into the gut cavity. In particular, the sensitive radio-frequency metal detection method with carbonyl powder showed very promising results in detection of marked feed. Results show also that Dual energy band X-ray imaging may have potential for prediction of fat content in the feed. Based on the investigations it can be concluded that both X-ray imaging and sensitive radio-frequency metal detector technology have the potential for detecting cod having consumed marked feed. These are all technologies that may be adapted to large scale handling of fish from fish cages. Thus, it may be possible to discriminate between unweaned and weaned cod in a large scale grading situation. Based on the results of this study, a suggestion for evaluation of concept for in-situ sorting system is presented. PMID:24743448

  12. Discrimination between weaned and unweaned Atlantic cod (Gadus morhua) in capture-based aquaculture (CBA) by X-ray imaging and radio-frequency metal detector.

    Science.gov (United States)

    Misimi, Ekrem; Martinsen, Svein; Mathiassen, John Reidar; Erikson, Ulf

    2014-01-01

    The aim of this study was to investigate the feasibility of two detection methods for use in discrimination and sorting of adult Atlantic cod (about 2 kg) in the small scale capture-based aquaculture (CBA). Presently, there is no established method for discrimination of weaned and unweaned cod in CBA. Generally, 60-70% of the wild-caught cod in the CBA are weaned into commercial dry feed. To increase profitability for the fish farmers, unweaned cod must be separated from the stock, meaning the fish must be sorted into two groups - unweaned and weaned from moist feed. The challenges with handling of large numbers of fish in cages, defined the limits of the applied technology. As a result, a working model was established, focusing on implementing different marking materials added to the fish feed, and different technology for detecting the feed presence in the fish gut. X-ray imaging in two modes (planar and dual energy band) and sensitive radio-frequency metal detection were the detection methods that were chosen for the investigations. Both methods were tested in laboratory conditions using dead fish with marked feed inserted into the gut cavity. In particular, the sensitive radio-frequency metal detection method with carbonyl powder showed very promising results in detection of marked feed. Results show also that Dual energy band X-ray imaging may have potential for prediction of fat content in the feed. Based on the investigations it can be concluded that both X-ray imaging and sensitive radio-frequency metal detector technology have the potential for detecting cod having consumed marked feed. These are all technologies that may be adapted to large scale handling of fish from fish cages. Thus, it may be possible to discriminate between unweaned and weaned cod in a large scale grading situation. Based on the results of this study, a suggestion for evaluation of concept for in-situ sorting system is presented.

  13. Dust tori in radio galaxies

    NARCIS (Netherlands)

    van der Wolk, G.; Barthel, P. D.; Peletier, R. F.; Pel, J. W.

    Aims. We investigate the quasar - radio galaxy unification scenario and detect dust tori within radio galaxies of various types. Methods. Using VISIR on the VLT, we acquired sub-arcsecond (similar to 0.40 '') resolution N-band images, at a wavelength of 11.85 mu m, of the nuclei of a sample of 27

  14. THE COORDINATED RADIO AND INFRARED SURVEY FOR HIGH-MASS STAR FORMATION. II. SOURCE CATALOG

    Energy Technology Data Exchange (ETDEWEB)

    Purcell, C. R.; Hoare, M. G.; Lumsden, S. L.; Urquhart, J. S. [School of Physics and Astronomy, E.C. Stoner Building, University of Leeds, Leeds LS2 9JT (United Kingdom); Cotton, W. D. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States); Chandler, C. [National Radio Astronomy Observatory, Array Operations Center, P.O. Box O, 1003 Lopezville Road, Socorro, NM 87801-0387 (United States); Churchwell, E. B. [The University of Wisconsin, Department of Astronomy, 475 North Charter Street, Madison, WI 53706 (United States); Diamond, P.; Fuller, G.; Garrington, S. T. [Jodrell Bank Centre for Astrophysics, The Alan Turing Building, School of Physics and Astronomy, The University of Manchester, Oxford Rd, Manchester, M13 9PL (United Kingdom); Dougherty, S. M. [National Research Council of Canada, Herzberg Institute for Astrophysics, Dominion Radio Astrophysical Observatory, P.O. Box 248, Penticton, British Columbia V2A 6J9 (Canada); Fender, R. P. [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Gledhill, T. M. [Science and Technology Research Institute, University of Hertfordshire, College Lane, Hatfield AL10 9AB (United Kingdom); Goldsmith, P. F. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Hindson, L. [CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia); Jackson, J. M. [Astronomy Department, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Kurtz, S. E. [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico - Morelia, Apartado Postal 3-72, C.P. 58090 Morelia, Michoacan (Mexico); Marti, J., E-mail: C.R.Purcell@leeds.ac.uk [Departamento de Fisica, EPSJ, Universidad de Jaen, Campus Las Lagunillas s/n, Edif. A3, E-23071 Jaen (Spain); and others

    2013-03-01

    The CORNISH project is the highest resolution radio continuum survey of the Galactic plane to date. It is the 5 GHz radio continuum part of a series of multi-wavelength surveys that focus on the northern GLIMPSE region (10 Degree-Sign < l < 65 Degree-Sign ), observed by the Spitzer satellite in the mid-infrared. Observations with the Very Large Array in B and BnA configurations have yielded a 1.''5 resolution Stokes I map with a root mean square noise level better than 0.4 mJy beam{sup -1}. Here we describe the data-processing methods and data characteristics, and present a new, uniform catalog of compact radio emission. This includes an implementation of automatic deconvolution that provides much more reliable imaging than standard CLEANing. A rigorous investigation of the noise characteristics and reliability of source detection has been carried out. We show that the survey is optimized to detect emission on size scales up to 14'' and for unresolved sources the catalog is more than 90% complete at a flux density of 3.9 mJy. We have detected 3062 sources above a 7{sigma} detection limit and present their ensemble properties. The catalog is highly reliable away from regions containing poorly sampled extended emission, which comprise less than 2% of the survey area. Imaging problems have been mitigated by down-weighting the shortest spacings and potential artifacts flagged via a rigorous manual inspection with reference to the Spitzer infrared data. We present images of the most common source types found: H II regions, planetary nebulae, and radio galaxies. The CORNISH data and catalog are available online at http://cornish.leeds.ac.uk.

  15. Continuum robots and underactuated grasping

    Directory of Open Access Journals (Sweden)

    N. Giri

    2011-02-01

    Full Text Available We discuss the capabilities of continuum (continuous backbone robot structures in the performance of under-actuated grasping. Continuum robots offer the potential of robust grasps over a wide variety of object classes, due to their ability to adapt their shape to interact with the environment via non-local continuum contact conditions. Furthermore, this capability can be achieved with simple, low degree of freedom hardware. However, there are practical issues which currently limit the application of continuum robots to grasping. We discuss these issues and illustrate via an experimental continuum grasping case study.

    This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010, 19 August 2010, Montréal, Canada.

  16. Continuum mechanics of anisotropic materials

    CERN Document Server

    Cowin, Stephen C

    2013-01-01

    Continuum Mechanics of Anisotropic Materials(CMAM) presents an entirely new and unique development of material anisotropy in the context of an appropriate selection and organization of continuum mechanics topics. These features will distinguish this continuum mechanics book from other books on this subject. Textbooks on continuum mechanics are widely employed in engineering education, however, none of them deal specifically with anisotropy in materials. For the audience of Biomedical, Chemical and Civil Engineering students, these materials will be dealt with more frequently and greater accuracy in their analysis will be desired. Continuum Mechanics of Anisotropic Materials' author has been a leader in the field of developing new approaches for the understanding of anisotropic materials.

  17. IHW COMET HALLEY RADIO CONTINUUM SUMMARIES V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA's International Halley Watch (IHW) has created a Comet Halley Archive. The collection of data spans the full wavelength range as submitted by scientists to the...

  18. Seyfert Galaxies: Radio Continuum Emission Properties and the ...

    Indian Academy of Sciences (India)

    Seyfert galaxies are classified mainly into type 1 and type 2 depending on the presence and absence of broad permitted emission lines in their optical spectra, respectively. Unification scheme hypothesizes that the observed similarities and differences between the two Seyfert subtypes can be understood as due to the ...

  19. Seyfert Galaxies: Radio Continuum Emission Properties and the ...

    Indian Academy of Sciences (India)

    Seyfert galaxies are classified mainly into type 1 and type 2 depending on the presence and absence of broad permitted emission lines in their optical spectra, respectively. Unification scheme hypothesizes that the observed similarities and differences between the two Seyfert sub- types can be understood as due to the ...

  20. Politics and Radio in the 1924 Campaign.

    Science.gov (United States)

    Berkman, Dave

    1987-01-01

    Discusses the relation between radio broadcasting and politics in the 1924 presidential campaign, focusing on newspaper and magazine coverage. Notes radio's influence on candidate image, the aspect of censorship, and the use of radio during the campaign and after the election. (MM)

  1. Solar Radio

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Scientists monitor the structure of the solar corona, the outer most regions of the Sun's atmosphere, using radio waves (100?s of MHz to 10?s of GHz). Variations in...

  2. Planck intermediate results: XLV. Radio spectra of northern extragalactic radio sources

    DEFF Research Database (Denmark)

    Ade, P. A R; Aghanim, N.; Aller, H. D.

    2016-01-01

    Continuum spectra covering centimetre to submillimetre wavelengths are presented for a northern sample of 104 extragalactic radio sources, mainly active galactic nuclei, based on four-epoch Planck data. The nine Planck frequencies, from 30 to 857 GHz, are complemented by a set of simultaneous gro...

  3. Continuum of Care (COC) Areas

    Data.gov (United States)

    Department of Housing and Urban Development — The purpose of the Continuum of Care (CoC) Homeless Assistance Programs is to reduce the incidence of homelessness in CoC communities by assisting homeless...

  4. The Very Large Array: Pioneering New Directions in Radio Astronomy

    Science.gov (United States)

    McKinnon, Mark

    2018-01-01

    The Very Large Array (VLA) started science operations in 1980 and was rechristened the Jansky VLA after a major upgrade to its electronics system was completed in 2012. The VLA plays a prominent role in scientific discovery through studies of the Solar System, star and planet formation, galaxy formation, and time domain astronomy. It has attained iconic status as one of the most scientifically productive telescopes on EarthIn 2017, three major initiatives were launched at the VLA with the goal of maintaining its leadership role and impact in radio astronomy in the near and long term future:1. In September, the VLA embarked upon the VLA Sky Survey (VLASS), the highest resolution survey ever undertaken at radio wavelengths. The survey was planned in consultation with the astronomy community and will be used to search for transients, study the polarization properties of extragalactic radio sources, and study highly obscured sources in our Galaxy.2. Detailed planning for a next generation VLA (ngVLA) began in earnest in 2017. The ngVLA will open a new window on the Universe through ultra-sensitive imaging of thermal line and continuum emission down to milliarcsecond resolution, as well as unprecedented broad-band continuum polarimetric imaging of non-thermal processes. A proposal for the instrument will be submitted to the 2020 Decadal Survey.3. A multi-year program to replace the 40+ year old infrastructure at the VLA site was initiated in 2017. The program includes the replacement of the VLA’s electrical infrastructure in 2018, improvements to the VLA rail system, and the replacement of heavy maintenance equipment.The VLA continued to play a major role in discovering and explaining the physics of transient phenomena in 2017, to include fast transients, such as fast radio bursts, and long time scale transients, such as novae, tidal disruption events, and gamma-ray bursts.More thorough descriptions of the VLASS and ngVLA, along with the science that can be done with

  5. Deep radio images of the HEGRA and Whipple TeV sources in the Cygnus OB2 region.

    OpenAIRE

    Martí Ribas, Josep; Paredes i Poy, Josep Maria; Ishwara-Chandra, C. H.; Bosch i Ramon, Valentí

    2007-01-01

    The modern generation of Cherenkov telescopes has revealed a new population of gamma-ray sources in the Galaxy. Some of them have been identified with previously known X-ray binary systems while other remain without clear counterparts a lower energies. Our initial goal here was reporting on extensive radio observations of the first extended and yet unidentified source, namely TeV J2032+4130. This object was originally detected by the HEGRA telescope in the direction of the Cygnus OB2 region a...

  6. Automated detection of extended sources in radio maps: progress from the SCORPIO survey

    Science.gov (United States)

    Riggi, S.; Ingallinera, A.; Leto, P.; Cavallaro, F.; Bufano, F.; Schillirò, F.; Trigilio, C.; Umana, G.; Buemi, C. S.; Norris, R. P.

    2016-08-01

    Automated source extraction and parametrization represents a crucial challenge for the next-generation radio interferometer surveys, such as those performed with the Square Kilometre Array (SKA) and its precursors. In this paper, we present a new algorithm, called CAESAR (Compact And Extended Source Automated Recognition), to detect and parametrize extended sources in radio interferometric maps. It is based on a pre-filtering stage, allowing image denoising, compact source suppression and enhancement of diffuse emission, followed by an adaptive superpixel clustering stage for final source segmentation. A parametrization stage provides source flux information and a wide range of morphology estimators for post-processing analysis. We developed CAESAR in a modular software library, also including different methods for local background estimation and image filtering, along with alternative algorithms for both compact and diffuse source extraction. The method was applied to real radio continuum data collected at the Australian Telescope Compact Array (ATCA) within the SCORPIO project, a pathfinder of the Evolutionary Map of the Universe (EMU) survey at the Australian Square Kilometre Array Pathfinder (ASKAP). The source reconstruction capabilities were studied over different test fields in the presence of compact sources, imaging artefacts and diffuse emission from the Galactic plane and compared with existing algorithms. When compared to a human-driven analysis, the designed algorithm was found capable of detecting known target sources and regions of diffuse emission, outperforming alternative approaches over the considered fields.

  7. Towards secondary use of heterogeneous radio-oncological data for retrospective clinical trials: service-oriented connection of a central research database with image analysis tools

    Science.gov (United States)

    Bougatf, Nina; Bendl, Rolf; Debus, Jürgen

    2015-03-01

    Our overall objective is the utilization of heterogeneous and distributed radio-oncological data in retrospective clinical trials. Previously, we have successfully introduced a central research database for collection of heterogeneous data from distributed systems. The next step is the integration of image analysis tools in the standard retrieval process. Hence, analyses for complex medical questions can be processed automatically and facilitated immensely. In radiation oncology recurrence analysis is a central approach for the evaluation of therapeutic concepts. However, various analysis steps have to be performed like image registration, dose transformation and dose statistics. In this paper we show the integration of image analysis tools in the standard retrieval process by connecting them with our central research database using a service-oriented approach. A concrete problem from recurrence analysis has been selected to prove our concept exemplarily. We implemented service-oriented data collection and analysis tools to use them in a central analysis platform, which is based on a work flow management system. An analysis work flow has been designed that, at first, identifies patients in the research database fulfilling the inclusion criteria. Then the relevant imaging data is collected. Finally the imaging data is analyzed automatically. After the successful work flow execution, the results are available for further evaluation by a physician. As a result, the central research database has been connected successfully with automatic data collection and image analysis tools and the feasibility of our service-oriented approach has been demonstrated. In conclusion, our approach will simplify retrospective clinical trials in our department in future.

  8. Coma cluster ultradiffuse galaxies are not standard radio galaxies

    Science.gov (United States)

    Struble, Mitchell F.

    2018-02-01

    Matching members in the Coma cluster catalogue of ultradiffuse galaxies (UDGs) from SUBARU imaging with a very deep radio continuum survey source catalogue of the cluster using the Karl G. Jansky Very Large Array (VLA) within a rectangular region of ∼1.19 deg2 centred on the cluster core reveals matches consistent with random. An overlapping set of 470 UDGs and 696 VLA radio sources in this rectangular area finds 33 matches within a separation of 25 arcsec; dividing the sample into bins with separations bounded by 5, 10, 20 and 25 arcsec finds 1, 4, 17 and 11 matches. An analytical model estimate, based on the Poisson probability distribution, of the number of randomly expected matches within these same separation bounds is 1.7, 4.9, 19.4 and 14.2, each, respectively, consistent with the 95 per cent Poisson confidence intervals of the observed values. Dividing the data into five clustercentric annuli of 0.1° and into the four separation bins, finds the same result. This random match of UDGs with VLA sources implies that UDGs are not radio galaxies by the standard definition. Those VLA sources having integrated flux >1 mJy at 1.4 GHz in Miller, Hornschemeier and Mobasher without SDSS galaxy matches are consistent with the known surface density of background radio sources. We briefly explore the possibility that some unresolved VLA sources near UDGs could be young, compact, bright, supernova remnants of Type Ia events, possibly in the intracluster volume.

  9. Radio astronomy

    CERN Document Server

    Alder, Berni

    1975-01-01

    Methods in Computational Physics, Volume 14: Radio Astronomy is devoted to the role of the digital computer both as a control device and as a calculator in addressing problems related to galactic radio noise. This volume contains four chapters and begins with a technical description of the hardware and the special data-handling problems of using radioheliography, with an emphasis on a selection of observational results obtained with the Culgoora radioheliograph and their significance to solar physics and to astrophysics in general. The subsequent chapter examines interstellar dispersion, i

  10. SUBARCSEC OPTICAL AND RADIO OBSERVATIONS OF THE ...

    African Journals Online (AJOL)

    2005-10-08

    Oct 8, 2005 ... MHz are presented. The radio image at L~band andB, V, R and 1 band images with a. 0.6 arcsec seeing resolve the components. These observations show that the brightness ratio of the components at optical bands is similar to those at radio hands. This strengthens the case for a gravitational lens ...

  11. Radio Astronomy and the Giant Metre-Wave Radio Telescope

    Indian Academy of Sciences (India)

    but the energy of each type of wave varies inversely with its wavelength. Thus ... parent to radio-waves; much of the galaxy is also transparent to ..... stars in the galaxies. The im- age has been inverted (like a film negative) so darker re- gions in the image are ac- tually brighter. In the opti- cal image the two galaxies.

  12. Digitale radio

    NARCIS (Netherlands)

    Schiphorst, Roelof; Zondervan, L.

    2007-01-01

    Als eerste in Europa heeft Nederland begin december 2006 de omschakeling van analoge naar digitale ethertelevisie gemaakt. Voor de analoge FM-radio is er ook een digitale variant, T-DAB. T-DAB staat voor 'Terrestrial Digital Audio Broadcasting'. Dit artikel gaat verder in op deze techniek en de

  13. Lagrangian continuum dynamics in ALEGRA.

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Michael K. W.; Love, Edward

    2007-12-01

    Alegra is an ALE (Arbitrary Lagrangian-Eulerian) multi-material finite element code that emphasizes large deformations and strong shock physics. The Lagrangian continuum dynamics package in Alegra uses a Galerkin finite element spatial discretization and an explicit central-difference stepping method in time. The goal of this report is to describe in detail the characteristics of this algorithm, including the conservation and stability properties. The details provided should help both researchers and analysts understand the underlying theory and numerical implementation of the Alegra continuum hydrodynamics algorithm.

  14. Submillimeter Continuum Observations of Comets

    Science.gov (United States)

    Jewitt, David

    1998-01-01

    The aim of this proposal was to study the submillimeter continuum emission from comets. The study was based mainly on the exploitation of the world's leading submillimeter telescope, the JCMT (James Clerk Maxwell Telescope) on Mauna Kea. Submillimeter wavelengths provide a unique view of cometary physics for one main reason. The cometary size distribution is such that the scattering cross-section is dominated by small dust grains, while the mass is dominated by the largest particles. Submillimeter continuum radiation samples cometary particles much larger than those sampled by more common observations at shorter (optical and infrared) wavelengths and therefore provides a nearly direct measure of the cometary dust mass.

  15. Shouldering the blame for impingement: the rotator cuff continuum

    African Journals Online (AJOL)

    Abstract. The aim of this article was to summarise recent research on shoulder impingement and rotator cuff pathology. A continuum model of rotator cuff pathology is described, and the challenges of accurate clinical diagnosis, imaging and best management discussed. ..... aging and morphologic changes in the rotator cuff.

  16. Shouldering the blame for impingement: the rotator cuff continuum ...

    African Journals Online (AJOL)

    ... research on shoulder impingement and rotator cuff pathology. A continuum model of rotator cuff pathology is described, and the challenges of accurate clinical diagnosis, imaging and best management discussed. Keywords: shoulder impingement syndrome, subacromial impingement syndrome, rotator cuff, tendinopathy, ...

  17. A NEW PERSPECTIVE OF THE RADIO BRIGHT ZONE AT THE GALACTIC CENTER: FEEDBACK FROM NUCLEAR ACTIVITIES

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jun-Hui [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Morris, Mark R. [Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, CA 90095 (United States); Goss, W. M., E-mail: jzhao@cfa.harvard.edu [NRAO, P.O. Box O, Socorro, NM 87801 (United States)

    2016-02-01

    New observations of Sgr A have been carried out with the Jansky VLA in the B and C arrays using the broadband (2 GHz) continuum mode at 5.5 GHz. The field of view covers the central 13′ (30 pc) region of the radio-bright zone at the Galactic center. Using the multi-scale and multi-frequency-synthesis (MS-MFS) algorithms in CASA, we have imaged Sgr A with a resolution of 1″, achieving an rms noise of 8 μJy beam{sup −1}, and a dynamic range of 100,000:1. Both previously known and newly identified radio features in this region are revealed, including numerous filamentary sources. The radio continuum image is compared with Chandra X-ray images, with a CN emission-line image obtained with the Submillimeter Array and with detailed Paschen-α images obtained with Hubble Space Telescope/NICMOS. We discuss several prominent features in the radio image. The “Sgr A west Wings” extend 2′ (5 pc) from the NW and SE tips of the Sgr A west H ii region (the “Mini-spiral”) to positions located 2.9 and 2.4 arcmin to the northwest and southeast of Sgr A*, respectively. The NW wing, along with several other prominent features, including the previously identified “NW Streamers,” form an elongated radio lobe (NW lobe), oriented nearly perpendicular to the Galactic plane. This radio lobe, with a size of 6.′3 × 3.′2 (14.4 pc × 7.3 pc), has a known X-ray counterpart. In the outer region of the NW lobe, a row of three thermally emitting rings is observed. A field containing numerous amorphous radio blobs extends for a distance of ∼2 arcmin beyond the tip of the SE wing; these newly recognized features coincide with the SE X-ray lobe. Most of the amorphous radio blobs in the NW and SE lobes have Paschen-α counterparts. We propose that they have been produced by shock interaction of ambient gas concentrations with a collimated nuclear wind or an outflow that originated from within the circumnuclear disk (CND). We also discuss the possibility that the ionized

  18. The geometry of continuum regularization

    Energy Technology Data Exchange (ETDEWEB)

    Halpern, M.B.

    1987-03-01

    This lecture is primarily an introduction to coordinate-invariant regularization, a recent advance in the continuum regularization program. In this context, the program is seen as fundamentally geometric, with all regularization contained in regularized DeWitt superstructures on field deformations.

  19. Resonantly Trapped Bound State in the Continuum Laser

    CERN Document Server

    Lepetit, Thomas; Kodigala, Ashok; Bahari, Babak; Fainman, Yeshaiahu; Kanté, Boubacar

    2015-01-01

    Cavities play a fundamental role in wave phenomena from quantum mechanics to electromagnetism and dictate the spatiotemporal physics of lasers. In general, they are constructed by closing all "doors" through which waves can escape. We report, at room temperature, a bound state in the continuum laser that harnesses optical modes residing in the radiation continuum but nonetheless may possess arbitrarily high quality factors. These counterintuitive cavities are based on resonantly trapped symmetry-compatible modes that destructively interfere. Our experimental demonstration opens exciting avenues towards coherent sources with intriguing topological properties for optical trapping, biological imaging, and quantum communication.

  20. Observational model of the ionized gas in Seyfert and radio-galaxy nuclei*

    Science.gov (United States)

    Osterbrock, Donald E.

    1978-01-01

    Equivalent widths of the total emission-line Hβ in Seyfert 1, Seyfert 2, and intermediate-type Seyfert galaxies, expressed in terms of the featureless continuum, all have approximately the same frequency distribution. This suggests that the energy-input mechanism to both the narrow-line, low-density gas and the broad-line, high-density gas is photoionization by the featureless continuum. The reason for the weakness of the narrow emission lines in extreme Seyfert 1 galaxies is then the absorption of most of the ionizing photons in the dense gas near the central source. The statistics of line widths can be fitted by a model in which the dense gas has typical rotational velocity 5000 km/sec and typical turbulent velocity 2000 km/sec. A model is proposed in which the dense gas forms a rotating, turbulent disk with dimension ≈0.1 pc and height/diameter ≈2/5. Seyfert 2 galaxies are objects with little dense gas, and intermediate-type Seyfert galaxies are objects in which the dense gas is optically thin to ionizing radiation at least along the poles. Most radio galaxies have strong narrow emission lines, suggesting that escape of radio plasma can only occur where some ionizing photons can also escape from the dense gas. Other predictions, implications, and tests of this model are discussed. Images PMID:16592488

  1. A high-field magnetic resonance imaging spectrometer using an oven-controlled crystal oscillator as the local oscillator of its radio frequency transceiver.

    Science.gov (United States)

    Liang, Xiao; Tang, Xin; Tang, Weinan; Gao, Jia-Hong

    2014-09-01

    A home-made high-field magnetic resonance imaging (MRI) spectrometer with multiple receiving channels is described. The radio frequency (RF) transceiver of the spectrometer consists of digital intermediate frequency (IF) circuits and corresponding mixing circuits. A direct digital synthesis device is employed to generate the IF pulse; the IF signal from a down-conversion circuit is sampled and followed by digital quadrature detection. Both the IF generation and the IF sampling use a 50 MHz clock. An oven-controlled crystal oscillator, which has outstanding spectral purity and a compact circuit, is used as the local oscillator of the RF transceiver. A digital signal processor works as the pulse programmer of the spectrometer, as a result, 32 control lines can be generated simultaneously while an event is triggered. Field programmable gate array devices are utilized as the auxiliary controllers of the IF generation, IF receiving, and gradient control. High performance, including 1 μs time resolution of the soft pulse, 1 MHz receiving bandwidth, and 1 μs time resolution of the gradient waveform, is achieved. High-quality images on a 1.5 T MRI system using the spectrometer are obtained.

  2. The Radio JOVE Project - Shoestring Radio Astronomy

    Science.gov (United States)

    Thieman, J.; Flagg, R.; Greenman, W.; Higgins, C.; Reyes, F.; Sky, J.

    2010-01-01

    Radio JOVE is an education and outreach project intended to give students and other interested individuals hands-on experience in learning radio astronomy. They can do this through building a radio telescope from a relatively inexpensive kit that includes the parts for a receiver and an antenna as well as software for a computer chart recorder emulator (Radio Skypipe) and other reference materials

  3. Homogenization of a Cauchy continuum towards a micromorphic continuum

    Science.gov (United States)

    Hütter, Geralf

    2017-02-01

    The micromorphic theory of Eringen and Mindlin, including special cases like strain gradient theory or Cosserat theory, is widely used to model size effects and localization phenomena. The heuristic construction of such theories based on thermodynamic considerations is well-established. However, the identification of corresponding constitutive laws and of the large number of respective constitutive parameters limits the practical application of such theories. In the present contribution, a closed procedure for the homogenization of a Cauchy continuum at the microscale towards a fully micromorphic continuum is derived including explicit definitions of all involved generalized macroscopic stress and deformation measures. The boundary value problem to be solved on the microscale is formulated either for using static or kinematic boundary conditions. The procedure is demonstrated with an example.

  4. Space Telecommunications Radio System STRS Cognitive Radio

    Science.gov (United States)

    Briones, Janette C.; Handler, Louis M.

    2013-01-01

    Radios today are evolving from awareness toward cognition. A software defined radio (SDR) provides the most capability for integrating autonomic decision making ability and allows the incremental evolution toward a cognitive radio. This cognitive radio technology will impact NASA space communications in areas such as spectrum utilization, interoperability, network operations, and radio resource management over a wide range of operating conditions. NASAs cognitive radio will build upon the infrastructure being developed by Space Telecommunication Radio System (STRS) SDR technology. This paper explores the feasibility of inserting cognitive capabilities in the NASA STRS architecture and the interfaces between the cognitive engine and the STRS radio. The STRS architecture defines methods that can inform the cognitive engine about the radio environment so that the cognitive engine can learn autonomously from experience, and take appropriate actions to adapt the radio operating characteristics and optimize performance.

  5. RADIO RECOMBINATION LINE OBSERVATIONS OF THE GALACTIC HII COMPLEX W3

    NARCIS (Netherlands)

    ROELFSEMA, PR; GOSS, WM

    The HII complex W3 has been observed at four different frequencies (325 MHz, 1.4 GHz, 4.9 GHz and 14.7 GHz) in the radio continuum and in a number of different radio recombination lines of hydrogen, helium and carbon. From these observations the global properties of the 9 main HII components have

  6. An expedition to continuum theory

    CERN Document Server

    Müller, Wolfgang H

    2014-01-01

    This book introduces field theory as required in solid and fluid mechanics as well as in electromagnetism. It also presents the necessary mathematical framework, namely tensor algebra and tensor calculus, by using an inductive approach, which makes it particularly suitable for beginners. In general, the book can be used in undergraduate classes on continuum theory and, more specifically, in courses on continuum mechanics, for students of physics and engineering alike. The benefits for the readers consist of providing a sound basis of the subject as a whole and of training their ability for solving specific problems in a rational manner.  For this purpose the general laws of nature in terms of the balances for mass, momentum, and energy are applied and combined with constitutive relations, which are material specific. Various examples and homework problems illustrate how to use the theory in daily practice. Numerous mini-biographies have been added to the mathematical text for diversion and amusement.

  7. A RADIO-SELECTED BLACK HOLE X-RAY BINARY CANDIDATE IN THE MILKY WAY GLOBULAR CLUSTER M62

    Energy Technology Data Exchange (ETDEWEB)

    Chomiuk, Laura; Ransom, Scott [National Radio Astronomy Observatory, 520 Edgemont Rd, Charlottesville, VA (United States); Strader, Jay [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Maccarone, Thomas J. [Department of Physics, Texas Tech University, Box 41051, Lubbock, TX 79409-1051 (United States); Miller-Jones, James C. A. [International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia); Heinke, Craig [Department of Physics, University of Alberta, 4-183 CCIS, Edmonton, AB T6G 2E1 (Canada); Noyola, Eva [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico (UNAM), A. P. 70-264, 04510 (Mexico); Seth, Anil C., E-mail: chomiuk@pa.msu.edu [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States)

    2013-11-01

    We report the discovery of a candidate stellar-mass black hole in the Milky Way globular cluster M62. We detected the black hole candidate, which we call M62-VLA1, in the core of the cluster using deep radio continuum imaging from the Karl G. Jansky Very Large Array. M62-VLA1 is a faint source with a flux density of 18.7 ± 1.9 μJy at 6.2 GHz and a flat radio spectrum (α = –0.24 ± 0.42, for S{sub ν} = ν{sup α}). M62 is the second Milky Way cluster with a candidate stellar-mass black hole; unlike the two candidate black holes previously found in the cluster M22, M62-VLA1 is associated with a Chandra X-ray source, supporting its identification as a black hole X-ray binary. Measurements of its radio and X-ray luminosity, while not simultaneous, place M62-VLA1 squarely on the well-established radio-X-ray correlation for stellar-mass black holes. In archival Hubble Space Telescope imaging, M62-VLA1 is coincident with a star near the lower red giant branch. This possible optical counterpart shows a blue excess, Hα emission, and optical variability. The radio, X-ray, and optical properties of M62-VLA1 are very similar to those for V404 Cyg, one of the best-studied quiescent stellar-mass black holes. We cannot yet rule out alternative scenarios for the radio source, such as a flaring neutron star or background galaxy; future observations are necessary to determine whether M62-VLA1 is indeed an accreting stellar-mass black hole.

  8. Finsler-Geometric Continuum Mechanics

    Science.gov (United States)

    2016-05-01

    in time at which a deformable solid body is considered undeformed, following the usual conven- tion of continuum physics.19 A differential manifold M...coordinates and their indices, which are denoted via lowercase rather than capital fonts. A differential manifold m of spatial dimension 3 is identified with a...Aberdeen Proving Ground, MD 21005-5066 primary author’s email: <johnclay@cims.nyu.edu>. Concepts from Finsler differential geometry are applied toward a

  9. Continuum representations of cellular solids

    Energy Technology Data Exchange (ETDEWEB)

    Neilsen, M.K.

    1993-09-01

    Cellular materials consist of interconnected struts or plates which form cells. The struts or plates are constructed from a variety of metals, polymers, ceramics and wood products. Cellular materials are often used in impact limiters for shipping containers to protect the contents from accidental impact events. These materials exhibit a variety of complex behavior when subjected to crushing loads. This research focuses on the development of continuum representations of cellular solids that can be used in the finite element analysis of shipping container accidents. A significant portion of this work is the development of a new methodology to relate localized deformations to appropriate constitutive descriptions. This methodology provides the insight needed to select constitutive descriptions for cellular solids that capture the localized deformations that are observed experimentally. Constitutive relations are developed for two different cellular materials, aluminum honeycomb and polyurethane foam. These constitutive relations are based on plasticity and continuum damage theories. Plasticity is used to describe the permanent deformation exhibited by both aluminum honeycomb and polyurethane foam. Continuum damage is needed to capture the change in elastic parameters due to cracking of the polyurethane cell wall materials. The new constitutive description of polyurethane foam is implemented in both static and dynamic finite element codes, and analytical and numerical predictions are compared with available experimental data.

  10. Probing the bias of radio sources at high redshift

    CSIR Research Space (South Africa)

    Passmoor, S

    2012-11-01

    Full Text Available The relationship between the clustering of dark matter and that of luminous matter is often described using the bias parameter. Here, we provide a new method to probe the bias of intermediate-to-high-redshift radio continuum sources for which...

  11. Coherence Inherent in an Incoherent Synchrotron Radio Source ...

    Indian Academy of Sciences (India)

    Galaxies: active—quasars: general—radiation mechanisms: non-thermal—radio continuum: general. 1. Introduction. It is well known that synchrotron radiation mechanism does not allow MASER type coherent emission .... been sometimes called in the literature a 'cosmic conspiracy' (Cotton et al. 1980). Although one ...

  12. Early changes in perfusion of glioblastoma during radio- and chemotherapy evaluated by T1-dynamic contrast enhanced magnetic resonance imaging

    DEFF Research Database (Denmark)

    Møller, Søren; Lundemann, Michael; Law, Ian

    2015-01-01

    BACKGROUND: The survival times of patients with glioblastoma differ widely and biomarkers that would enable individualized treatment are needed. The objective of this study was to measure changes in the vascular physiology of tumor using T1-dynamic contrast enhanced magnetic resonance imaging (DCE...... months post-Tx. DCE-MRI at three Tesla generated maps of blood flow (BF), blood volume (BV), permeability (Ki) and volume of distribution (Vd) using a combination of model-free deconvolution and Patlak plots. Regions of interest in contrast enhancing tumor and in normal appearing white matter were...

  13. Radiology resident MR and CT image analysis skill assessment using an interactive volumetric simulation tool - the RadioLOG project.

    Science.gov (United States)

    Gondim Teixeira, Pedro Augusto; Cendre, Romain; Hossu, Gabriela; Leplat, Christophe; Felblinger, Jacques; Blum, Alain; Braun, Marc

    2017-02-01

    Assess the use of a volumetric simulation tool for the evaluation of radiology resident MR and CT interpretation skills. Forty-three participants were evaluated with a software allowing the visualisation of multiple volumetric image series. There were 7 medical students, 28 residents and 8 senior radiologists among the participants. Residents were divided into two sub-groups (novice and advanced). The test was composed of 15 exercises on general radiology and lasted 45 min. Participants answered a questionnaire on their experience with the test using a 5-point Likert scale. This study was approved by the dean of the medical school and did not require ethics committee approval. The reliability of the test was good with a Cronbach alpha value of 0.9. Test scores were significantly different in all sub-groups studies (p radiological practice (3.9 ± 0.9 on a 5-point scale) and was better than the conventional evaluation methods (4.6 ± 0.5 on a 5-point scale). This software provides a high quality evaluation tool for the assessment of the interpretation skills in radiology residents. • This tool allows volumetric image analysis of MR and CT studies. • A high reliability test could be created with this tool. • Test scores were strongly associated with the examinee expertise level. • Examinees positively evaluated the authenticity and usability of this tool.

  14. Use of a radio frequency shield during 1.5 and 3.0 Tesla magnetic resonance imaging: experimental evaluation

    Directory of Open Access Journals (Sweden)

    Favazza CP

    2014-10-01

    Full Text Available Christopher P Favazza, Deirdre M King, Heidi A Edmonson, Joel P Felmlee, Phillip J Rossman, Nicholas J Hangiandreou, Robert E Watson, Krzysztof R Gorny Department of Radiology, Mayo Clinic, Rochester, MN, USA Abstract: Radiofrequency (RF shields have been recently developed for the purpose of shielding portions of the patient's body during magnetic resonance imaging (MRI examinations. We present an experimental evaluation of a commercially available RF shield in the MRI environment. All tests were performed on 1.5 T and 3.0 T clinical MRI scanners. The tests were repeated with and without the RF shield present in the bore, for comparison. Effects of the shield, placed within the scanner bore, on the RF fields generated by the scanner were measured directly using tuned pick-up coils. Attenuation, by as much as 35 dB, of RF field power was found inside the RF shield. These results were supported by temperature measurements of metallic leads placed inside the shield, in which no measurable RF heating was found. In addition, there was a small, simultaneous detectable increase (~1 dB of RF power just outside the edges of the shield. For these particular scanners, the autocalibrated RF power levels were reduced for scan locations prescribed just outside the edges of the shield, which corresponded with estimations based on the pick-up coil measurements. Additionally, no significant heating during MRI scanning was observed on the shield surface. The impact of the RF shield on the RF fields inside the magnet bore is likely to be dependent on the particular model of the RF shield or the MRI scanner. These results suggest that the RF shield could be a valuable tool for clinical MRI practices. Keywords: radiofrequency shield, magnetic resonance imaging, radiofrequency attenuation

  15. The radio properties of infrared-faint radio sources

    Science.gov (United States)

    Middelberg, E.; Norris, R. P.; Hales, C. A.; Seymour, N.; Johnston-Hollitt, M.; Huynh, M. T.; Lenc, E.; Mao, M. Y.

    2011-02-01

    Context. Infrared-faint radio sources (IFRS) are objects that have flux densities of several mJy at 1.4 GHz, but that are invisible at 3.6 μm when using sensitive Spitzer observations with μJy sensitivities. Their nature is unclear and difficult to investigate since they are only visible in the radio. Aims: High-resolution radio images and comprehensive spectral coverage can yield constraints on the emission mechanisms of IFRS and can give hints to similarities with known objects. Methods: We imaged a sample of 17 IFRS at 4.8 GHz and 8.6 GHz with the Australia Telescope Compact Array to determine the structures on arcsecond scales. We added radio data from other observing projects and from the literature to obtain broad-band radio spectra. Results: We find that the sources in our sample are either resolved out at the higher frequencies or are compact at resolutions of a few arcsec, which implies that they are smaller than a typical galaxy. The spectra of IFRS are remarkably steep, with a median spectral index of -1.4 and a prominent lack of spectral indices larger than -0.7. We also find that, given the IR non-detections, the ratio of 1.4 GHz flux density to 3.6 μm flux density is very high, and this puts them into the same regime as high-redshift radio galaxies. Conclusions: The evidence that IFRS are predominantly high-redshift sources driven by active galactic nuclei (AGN) is strong, even though not all IFRS may be caused by the same phenomenon. Compared to the rare and painstakingly collected high-redshift radio galaxies, IFRS appear to be much more abundant, but less luminous, AGN-driven galaxies at similar cosmological distances.

  16. The Far-Infrared Emission of Radio Loud and Radio Quiet Quasars

    Science.gov (United States)

    Polletta, M.; Courvoisier, T. J.-L.; Wilkes, B. J.; Hooper, E. J.

    2000-01-01

    Continuum observations at radio, millimeter, infrared and soft X-ray energies are presented for a sample of 22 quasars, consisting of flat and steep spectrum radio loud, radio intermediate and radio quiet objects. The primary observational distinctions, among the different kinds of quasars in the radio and IR energy domains are studied using large observational datasets provided by ISOPHOT on board the Infrared Space Observatory, by the IRAM interferometer, by the sub-millimetre array SCUBA on JCMT, and by the European Southern Observatory (ESO) facilities IRAC1 on the 2.2 m telescope and SEST. The spectral energy distributions of all quasars from radio to IR energies are analyzed and modeled with non-thermal and thermal spectral components. The dominant mechanism emitting in the far/mid-IR is thermal dust emission in all quasars, with the exception of flat spectrum radio loud quasars for which the presence of thermal IR emission remains rather uncertain, since it is difficult to separate it from the bright non-thermal component. The dust is predominantly heated by the optical/ultraviolet radiation emitted from the external components of the AGN. A starburst contributes to the IR emission at different levels, but always less than the AGN (<= 27%). The distribution of temperatures, sizes, masses, and luminosities of the emitting dust are independent of the quasar type.

  17. Radiology resident MR and CT image analysis skill assessment using an interactive volumetric simulation tool - the RadioLOG project

    Energy Technology Data Exchange (ETDEWEB)

    Gondim Teixeira, Pedro Augusto; Leplat, Christophe [CHRU-Nancy Hopital Central, Service d' Imagerie Guilloz, Nancy (France); Universite de Lorraine, IADI U947, Nancy (France); Cendre, Romain [INSERM, CIC-IT 1433, Nancy (France); Hossu, Gabriela; Felblinger, Jacques [Universite de Lorraine, IADI U947, Nancy (France); INSERM, CIC-IT 1433, Nancy (France); Blum, Alain [CHRU-Nancy Hopital Central, Service d' Imagerie Guilloz, Nancy (France); Braun, Marc [CHRU-Nancy Hopital Central, Service de Neuroradiologie, Nancy (France)

    2017-02-15

    Assess the use of a volumetric simulation tool for the evaluation of radiology resident MR and CT interpretation skills. Forty-three participants were evaluated with a software allowing the visualisation of multiple volumetric image series. There were 7 medical students, 28 residents and 8 senior radiologists among the participants. Residents were divided into two sub-groups (novice and advanced). The test was composed of 15 exercises on general radiology and lasted 45 min. Participants answered a questionnaire on their experience with the test using a 5-point Likert scale. This study was approved by the dean of the medical school and did not require ethics committee approval. The reliability of the test was good with a Cronbach alpha value of 0.9. Test scores were significantly different in all sub-groups studies (p < 0.0225). The relation between test scores and the year of residency was logarithmic (R{sup 2} = 0.974). Participants agreed that the test reflected their radiological practice (3.9 ± 0.9 on a 5-point scale) and was better than the conventional evaluation methods (4.6 ± 0.5 on a 5-point scale). This software provides a high quality evaluation tool for the assessment of the interpretation skills in radiology residents. (orig.)

  18. Use of a radio frequency shield during 1.5 and 3.0 Tesla magnetic resonance imaging: experimental evaluation.

    Science.gov (United States)

    Favazza, Christopher P; King, Deirdre M; Edmonson, Heidi A; Felmlee, Joel P; Rossman, Phillip J; Hangiandreou, Nicholas J; Watson, Robert E; Gorny, Krzysztof R

    2014-01-01

    Radiofrequency (RF) shields have been recently developed for the purpose of shielding portions of the patient's body during magnetic resonance imaging (MRI) examinations. We present an experimental evaluation of a commercially available RF shield in the MRI environment. All tests were performed on 1.5 T and 3.0 T clinical MRI scanners. The tests were repeated with and without the RF shield present in the bore, for comparison. Effects of the shield, placed within the scanner bore, on the RF fields generated by the scanner were measured directly using tuned pick-up coils. Attenuation, by as much as 35 dB, of RF field power was found inside the RF shield. These results were supported by temperature measurements of metallic leads placed inside the shield, in which no measurable RF heating was found. In addition, there was a small, simultaneous detectable increase (∼1 dB) of RF power just outside the edges of the shield. For these particular scanners, the autocalibrated RF power levels were reduced for scan locations prescribed just outside the edges of the shield, which corresponded with estimations based on the pick-up coil measurements. Additionally, no significant heating during MRI scanning was observed on the shield surface. The impact of the RF shield on the RF fields inside the magnet bore is likely to be dependent on the particular model of the RF shield or the MRI scanner. These results suggest that the RF shield could be a valuable tool for clinical MRI practices.

  19. Analogies between continuum dislocation theory, continuum mechanics and fluid mechanics

    Science.gov (United States)

    Silbermann, C. B.; Ihlemann, J.

    2017-03-01

    Continuum Dislocation Theory (CDT) relates gradients of plastic deformation in crystals with the presence of geometrically necessary dislocations. Interestingly, CDT shows striking analogies to other branches of continuum mechanics. The present contribution demonstrates this on two essential kinematical quantities which reflect tensorial dislocation properties: the (resultant) Burgers vector and the dislocation density tensor. First, the limiting process for the (resultant) Burgers vector from an integral to a local quantity is performed analogously to the limiting process from the force vector to the traction vector. By evaluating the balance of forces on a tetrahedral volume element, Cauchy found his famous formula relating traction vector and stress tensor. It is shown how this procedure may be adopted to a continuously dislocated tetrahedron. Here, the conservation of Burger’s vector implicates the introduction of the dislocation density tensor. Second, analogies between the plastic flow of a continuously dislocated solid and the liquid flow of a fluid are highlighted: the resultant Burgers vector of a dislocation ensemble plays a similar role as the (resultant) circulation of a vortex tube. Moreover, both vortices within flowing fluids and dislocations within deforming solids induce discontinuities in the velocity field and the plastic distortion field, respectively. Beyond the analogies, some peculiar properties of the dislocation density tensor are presented as well.

  20. SPAM: A data reduction recipe for high-resolution,low-frequency radio-interferometric observations

    Science.gov (United States)

    Intema, H. T.

    High-resolution astronomical imaging at sub-GHz radio frequencies has been available for more than 15 years, with the VLA at 74 and 330 MHz, and the GMRT at 150, 240, 330 and 610 MHz. Recent developments include wide-bandwidth upgrades for VLA and GMRT, and commissioning of the aperture-array-based, multibeam telescope LOFAR. A common feature of these telescopes is the necessity to deconvolve the very many detectable sources within their wide fields-of-view and beyond. This is complicated by gain variations in the radio signal path that depend on viewing direction. One such example is phase errors due to the ionosphere. Here I discuss the inner workings of SPAM, a set of AIPS-based data reduction scripts in Python that includes direction-dependent calibration and imaging. Since its first version in 2008, SPAM has been applied to many GMRT data sets at various frequencies. Many valuable lessons were learned, and translated into various SPAM software modifications. Nowadays, semi-automated SPAM data reduction recipes can be applied to almost any GMRT data set, yielding good quality continuum images comparable with (or often better than) hand-reduced results. SPAM is currently being migrated from AIPS to CASA with an extension to handle wide bandwidths. This is aimed at providing users of the VLA low-band system and the upcoming widebandwidth GMRT with the necessary data reduction tools.

  1. Continuum mechanics of electromagnetic solids

    CERN Document Server

    Maugin, GA

    1988-01-01

    This volume is a rigorous cross-disciplinary theoretical treatment of electromechanical and magnetomechanical interactions in elastic solids. Using the modern style of continuum thermomechanics (but without excessive formalism) it starts from basic principles of mechanics and electromagnetism, and goes on to unify these two fields in a common framework. It treats linear and nonlinear static and dynamic problems in a variety of elastic solids such as piezoelectrics, electricity conductors, ferromagnets, ferroelectrics, ionic crystals and ceramics. Chapters 1-3 are introductory, describing the e

  2. AO Observations of Three Powerful Radio Galaxies

    Energy Technology Data Exchange (ETDEWEB)

    de Vries, W; van Bruegel, W; Quirrenbach, A

    2002-08-01

    The host galaxies of powerful radio sources are ideal laboratories to study active galactic nuclei (AGN). The galaxies themselves are among the most massive systems in the universe, and are believed to harbor supermassive black holes (SMBH). If large galaxies are formed in a hierarchical way by multiple merger events, radio galaxies at low redshift represent the end-products of this process. However, it is not clear why some of these massive ellipticals have associated radio emission, while others do not. Both are thought to contain SMBHs, with masses proportional to the total luminous mass in the bulge. It either implies every SMBH has recurrent radio-loud phases, and the radio-quiet galaxies happen to be in the ''low'' state, or that the radio galaxy nuclei are physically different from radio-quiet ones, i.e. by having a more massive SMBH for a given bulge mass. Here we present the first results from our adaptive optics imaging and spectroscopy pilot program on three nearby powerful radio galaxies. Initiating a larger, more systematic AO survey of radio galaxies (preferentially with Laser Guide Star equipped AO systems) has the potential of furthering our understanding of the physical properties of radio sources, their triggering, and their subsequent evolution.

  3. GBT CHANG-ES: Enhancing Radio Halos in Edge-on Galaxies Through Short-Spacing Corrections

    Science.gov (United States)

    Trent Braun, Timothy; Kepley, Amanda; Rand, Richard J.; Mason, Brian Scott; CHANG-ES

    2018-01-01

    We present L- and C-band continuum Stokes I data from the Green Bank Telescope (GBT) of 35 edge-on spiral galaxies that are part of the Continuum Halos in Nearby Galaxies, an EVLA Survey (CHANG-ES). CHANG-ES is an Expanded Very Large Array (EVLA) large program to measure radio continuum emission from the halos of 35 edge-on spiral galaxies in order to address a wide variety of science goals, including constraining the structure of magnetic fields, understanding the origins of radio halos, and probing both cosmic ray transport and cosmic ray driven winds. These goals can be reached by studying radio halo scale heights, spectral index variations with height, and the distribution of intensity and position angle of polarized emission. In particular, we are interested in modeling non-thermal presssure gradients in the gaseous halos of nearby galaxies to predict how they contribute to the decrease in the rotation of extraplanar gas with increasing height off of the galactic midplanes (lagging halos). Ultimately, the study of lagging halos will help us probe the efficacy of gas cycling between the disk and the halo in nearby galaxies. Crucial to this and the rest of the CHANG-ES analysis is the combination of the VLA data (B,C,D configurations in L-band and C,D configurations in C-band) with the GBT data in order to fill in the missing short-spacings in the u-v plane, which increases our sensitivity to large-scale emission and allows us to recover the total flux density. We present preliminary results from two methods of combining single-dish and interferometic data, namely the use of GBT data cubes as a model for the CASA task tclean and combining the Fourier transforms of the images as weighted sums in the u-v plane (feathering). Lastly, we detail our new data reduction pipeline for our wideband GBT continuum data, with an emphasis on the application of a least-squares basket-weaving technique used to remove striping image artifacts that notoriously plague single

  4. The continuum disordered pinning model.

    Science.gov (United States)

    Caravenna, Francesco; Sun, Rongfeng; Zygouras, Nikos

    Any renewal processes on [Formula: see text] with a polynomial tail, with exponent [Formula: see text], has a non-trivial scaling limit, known as the [Formula: see text]-stable regenerative set. In this paper we consider Gibbs transformations of such renewal processes in an i.i.d. random environment, called disordered pinning models. We show that for [Formula: see text] these models have a universal scaling limit, which we call the continuum disordered pinning model (CDPM). This is a random closed subset of [Formula: see text] in a white noise random environment, with subtle features:Any fixed a.s. property of the [Formula: see text]-stable regenerative set (e.g., its Hausdorff dimension) is also an a.s. property of the CDPM, for almost every realization of the environment.Nonetheless, the law of the CDPM is singular with respect to the law of the [Formula: see text]-stable regenerative set, for almost every realization of the environment. The existence of a disordered continuum model, such as the CDPM, is a manifestation of disorder relevance for pinning models with [Formula: see text].

  5. Nonlocal models in continuum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, N.L. [Los Alamos National Lab., NM (United States); Phan-Thien, N. [Sydney Univ., NSW (Australia). Dept. of Mechanical Engineering

    1993-09-01

    The recent appearance of nonlocal methods is examined in the light of traditional continuum mechanics. A comparison of nonlocal approaches in the fields of solid and fluid mechanics reveals that no consistent definition of a nonlocal theory has been used. We suggest a definition based on the violation of the principle of local action in continuum mechanics. From the consideration of the implications of a nonlocal theory based on this definition, we conclude that constitutive relations with nonlocal terms can confuse the traditional separation of the roles between conservation laws and constitutive relations. The diversity of motivations for the nonlocal approaches are presented, resulting primarily from deficiencies in numerical solutions to practical problems. To illustrate these concepts, the history of nonlocal terms in the field of viscoelastic fluids is reviewed. A specific example of a viscoelastic constitutive relation that contains a stress diffusion term is applied to a simple shear flow and found not to be a physical description of any known fluid. We conclude by listing questions that should be asked of nonlocal approaches.

  6. INVISIBLE ACTIVE GALACTIC NUCLEI. II. RADIO MORPHOLOGIES AND FIVE NEW H i 21 cm ABSORPTION LINE DETECTORS

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Ting; Stocke, John T.; Darling, Jeremy [Center for Astrophysics and Space Astronomy, UCB 389, University of Colorado, Boulder, CO 80309-0389 (United States); Momjian, Emmanuel [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Sharma, Soniya [Research School of Astronomy and Astrophysics, The Australian National University, Mt Stromlo Observatory, ACT 2611 (Australia); Kanekar, Nissim [National Centre for Radio Astrophysics, TIFR, Post Bag 3, Ganeshkhind, Pune 411 007 (India)

    2016-03-15

    This is the second paper directed toward finding new highly redshifted atomic and molecular absorption lines at radio frequencies. To this end, we selected a sample of 80 candidates for obscured radio-loud active galactic nuclei (AGNs) and presented their basic optical/near-infrared (NIR) properties in Paper I. In this paper, we present both high-resolution radio continuum images for all of these sources and H i 21 cm absorption spectroscopy for a few selected sources in this sample. A-configuration 4.9 and 8.5 GHz Very Large Array continuum observations find that 52 sources are compact or have substantial compact components with size <0.″5 and flux densities >0.1 Jy at 4.9 GHz. The 36 most compact sources were then observed with the Very Long Baseline Array at 1.4 GHz. One definite and 10 candidate Compact Symmetric Objects (CSOs) are newly identified, which is a detection rate of CSOs ∼three times higher than the detection rate previously found in purely flux-limited samples. Based on possessing compact components with high flux densities, 60 of these sources are good candidates for absorption-line searches. Twenty-seven sources were observed for H i 21 cm absorption at their photometric or spectroscopic redshifts with only six detections (five definite and one tentative). However, five of these were from a small subset of six CSOs with pure galaxy optical/NIR spectra (i.e., any AGN emission is obscured) and for which accurate spectroscopic redshifts place the redshifted 21 cm line in a radio frequency intereference (RFI)-free spectral “window” (i.e., the percentage of H i 21 cm absorption-line detections could be as high as ∼90% in this sample). It is likely that the presence of ubiquitous RFI and the absence of accurate spectroscopic redshifts preclude H i detections in similar sources (only 1 detection out of the remaining 22 sources observed, 13 of which have only photometric redshifts); that is, H i absorption may well be present but is masked by

  7. Minimally invasive radio-guided parathyroidectomy on a group of 452 primary hyperparathyroid patients. Refinement of preoperative imaging and intraoperative procedure

    Energy Technology Data Exchange (ETDEWEB)

    Rubello, D. [' S. Maria della Misericordia' Rovigo Hospital, Ist. Oncologico Veneto (IOV), Rovigo (Italy). Nuclear Medicine Service, PET Unit; Mariani, G. [Univ. of Pisa Medical School (Italy). Regional Center of Nuclear Medicine; Pelizzo, M.R. [Univ. of Padova Medical School (Italy). Dept. of Special Surgery

    2007-07-01

    The aim of this study was to investigate the efficacy of minimally invasive radio-guided parathyroidectomy (MIRP) in primary hyperparathyroid (PHPT) patients. Patients, methods: 452 consecutive PHPT patients were evaluated. Inclusion criteria for MIRP were (a) evidence at scintigraphy of a solitary parathyroid adenoma (PA); (b) a clear sestamibi uptake in the PA; (c) the absence of concomitant thyroid nodules; (d) no history of familial HPT or MEN; (e) no history of previous neck irradiation. Intra-operative protocol consisted of the injection of a low 37 MBq sestamibi dose in the operating suite 10 min before surgery. A hand held 11-mm collimated gamma probe was used. Quick PTH (QPTH) was routinely measured. Results: 344 out of the 452 patients met the inclusion criteria, and MIRP was successfully performed in 321 of them (93.3%). No major intra-operative complication was recorded. MIRP required a mean operative time of 32 min, and a mean hospital stay of 1.2 d. The parathyroid to background ratio (P/B) calculated by the probe was well correlated with the P/B calculated by sestamibi SPECT (r = 0.91; p <0.01), while no significant correlation was found between the probe-calculated P/B and the P/B calculated at planar sestamibi scan. Conclusions: In our experience: (a) an accurate preoperative localising imaging protocol based on planar and SPECT sestamibi scan, and neck US is effective in selecting PHPT patients for MIRP, (b) the P/B calculated by sestamibi SPECT seems able to predict the probe-calculated P/B more accurately than the P/B calculated at planar scan, (c) the low 37 MBq sestamibi dose protocol proved to be a safe and effective approach to perform MIRP. (orig.)

  8. Extension versus Bending for Continuum Robots

    Directory of Open Access Journals (Sweden)

    George Grimes

    2008-11-01

    Full Text Available In this paper, we analyze the capabilities of a novel class of continuous-backbone ("continuum" robots. These robots are inspired by biological "trunks, and tentacles". However, the capabilities of established continuum robot designs, which feature controlled bending but not extension, fall short of those of their biological counterparts. In this paper, we argue that the addition of controlled extension provides dual and complementary functionality, and correspondingly enhanced performance, in continuum robots. We present an interval-based analysis to show how the inclusion of controllable extension significantly enhances the workspace and capabilities of continuum robots.

  9. 77 FR 45367 - Continuum of Care Homeless Assistance Grant Application; Continuum of Care Application

    Science.gov (United States)

    2012-07-31

    ... strategic planning activities, performance, homeless populations, and data collection methods. This... Assistance application which collects data about the CoC's strategic planning activities, performance... URBAN DEVELOPMENT Continuum of Care Homeless Assistance Grant Application; Continuum of Care Application...

  10. What Are “X-shaped” Radio Sources Telling Us? II. Properties of a Sample of 87

    Science.gov (United States)

    Saripalli, Lakshmi; Roberts, David H.

    2018-01-01

    In an earlier paper, we presented Jansky Very Large Array multi-frequency, multi-array continuum imaging of a unique sample of low-axial ratio radio galaxies. In this paper, the second in the series, we examine the images to learn the phenomenology of how the off-axis emission relates to the main radio source. Inversion-symmetric offset emission appears to be bimodal and to originate from one of two strategic locations: outer ends of radio lobes (outer-deviation) or from inner ends (inner-deviation). The latter sources are almost always associated with edge-brightened sources. With S- and Z-shaped sources being a subset of outer-deviation sources, this class lends itself naturally to explanations involving black hole axis precession. Our data allow us to present a plausible model for the more enigmatic inner-deviation sources with impressive wings; as for outer-deviation sources these too require black hole axis shifts, although they also require plasma backflows into relic channels. Evolution in morphology over time relates the variety in structures in inner-deviation sources including XRGs. With features such as non-collinearities, central inner-S “spine,” corresponding lobe emission peaks, double and protruding hotspots not uncommon, black hole axis precession, drifts, or flips could be active in a significant fraction of radio sources with prominent off-axis emission. At least 4% of radio galaxies appear to undergo black hole axis rotation. Quasars offer a key signature for recognizing rotating axes. With a rich haul of sources that have likely undergone axis rotation, our work shows the usefulness of low-axial ratio sources in pursuing searches for binary supermassive black holes.

  11. Information Content in Radio Waves: Student Investigations in Radio Science

    Science.gov (United States)

    Jacobs, K.; Scaduto, T.

    2013-12-01

    We describe an inquiry-based instructional unit on information content in radio waves, created in the summer of 2013 as part of a MIT Haystack Observatory (Westford, MA) NSF Research Experiences for Teachers (RET) program. This topic is current and highly relevant, addressing science and technical aspects from radio astronomy, geodesy, and atmospheric research areas as well as Next Generation Science Standards (NGSS). Projects and activities range from simple classroom demonstrations and group investigations, to long term research projects incorporating data acquisition from both student-built instrumentation as well as online databases. Each of the core lessons is applied to one of the primary research centers at Haystack through an inquiry project that builds on previously developed units through the MIT Haystack RET program. In radio astronomy, students investigate the application of a simple and inexpensive software defined radio chip (RTL-SDR) for use in systems implementing a small and very small radio telescope (SRT and VSRT). Both of these systems allow students to explore fundamental principles of radio waves and interferometry as applied to radio astronomy. In ionospheric research, students track solar storms from the initial coronal mass ejection (using Solar Dynamics Observatory images) to the resulting variability in total electron density concentrations using data from the community standard Madrigal distributed database system maintained by MIT Haystack. Finally, students get to explore very long-baseline interferometry as it is used in geodetic studies by measuring crustal plate displacements over time. Alignment to NextGen standards is provided for each lesson and activity with emphasis on HS-PS4 'Waves and Their Applications in Technologies for Information Transfer'.

  12. The Co-creation Continuum

    DEFF Research Database (Denmark)

    Ind, Nicholas; Iglesias, Oriol; Markovic, Stefan

    2017-01-01

    Co-creation can open up a brand to the outside world and help it to generate relevant innovations. However, there is scarce empirical evidence as to how managers actually use co-creation to connect with customers and other stakeholders and build enduring innovation-oriented relationships with them....... To better understand this, as well as the assumptions of managers and the barriers they encounter in realizing the potential of co-creation, the authors have conducted 20 semi-structured interviews with managers that have led co-creation initiatives for 20 brands. This research finds diverse views of co-creation...... - from tactical market research tool to strategic collaborative innovation method, and shows that brands can be positioned along a continuum between these two polarities. This article also presents the implications for those that want to seize the potential of co-creation....

  13. A 45-MHz continuum survey of the northern hemisphere

    Science.gov (United States)

    Maeda, K.; Alvarez, H.; Aparici, J.; May, J.; Reich, P.

    We present a 45-MHz continuum survey in the declination range of +5 to +65 degrees in sets of maps in galactic and equatorial coordinates (epoch 1950). The observations were made at 46.5 MHz with a circular filled array of the Japanese Middle and Upper Atmosphere Radar (MU Radar) located at Shigaraki, Japan. The radar array consists of 475 crossed 3-element Yagis arranged within a circle of 103 m diameter, with a the half-power beam width of 3.6 degrees. In order to calibrate the data from the MU radar we used the Chilean 45-MHz survey which was made with an array of size comparable with that of the MU radar. The data processing was performed at the Maipu Radio Observatory, University of Chile, and this process brought the data to 45 MHz. The final maps were obtained at the Max-Plank-Institut fur Radioastronomie, Germany, using of the NOD2 program package.

  14. Physics of the continuum of borromean nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Vaagen, J.S.; Rogde, T. [Dept. of Physics, Univ. of Bergen (Norway); Danilin, B.V. [RRC The Kurchatov Inst., Kurchatov, Moscow (Russian Federation); Ershov, S.N. [JINR, Dubna, Moscow (Russian Federation); Thompson, I.J. [Dept. of Physics, Univ. of Surrey, Guildford (United Kingdom); Zhukov, M.V. [Chalmers Univ. of Technology and Goeteborg Univ., Goeteborg (Sweden); RNBT Collaboration

    1998-06-01

    The continuum states of two-neutron halo nuclei are calculated in the method of hyperspherical harmonics. Using DWIA theory appropriate for dilute halo matter we have probed the structure of the low-lying {sup 6}He continuum via calculations of charge-exchange and inelastic scattering. (orig.)

  15. Radio frequency detection assembly and method for detecting radio frequencies

    Science.gov (United States)

    Cown, Steven H.; Derr, Kurt Warren

    2010-03-16

    A radio frequency detection assembly is described and which includes a radio frequency detector which detects a radio frequency emission produced by a radio frequency emitter from a given location which is remote relative to the radio frequency detector; a location assembly electrically coupled with the radio frequency detector and which is operable to estimate the location of the radio frequency emitter from the radio frequency emission which has been received; and a radio frequency transmitter electrically coupled with the radio frequency detector and the location assembly, and which transmits a radio frequency signal which reports the presence of the radio frequency emitter.

  16. Monitoring the Continuum Emission from Active Galactic Nuclei with the SARA 0.9-m Telescope

    Science.gov (United States)

    Rumstay, K. S.; Morrill, A. L.

    1995-12-01

    CCD images of seven active galactic nuclei were obtained during the period July 7-11 1995 with the 0.9-m telescope operated at Kitt Peak by the Southeastern Association for Research in Astronomy (SARA). Six of these objects (Mrk 335, Mrk 590, NGC 4151, NGC 5548, Mrk 817, and Mrk 509) are Seyfert galaxies; the seventh is the broad-line radio galaxy 3C-390.3. The objects were selected from the sample of eleven active galactic nuclei whose emission spectra are routinely monitored with the Ohio State University 1.8-m telescope in Flagstaff, Arizona. These observations mark the beginning of a continuing program to use the SARA observing facility to monitor the continuum emission from these eleven AGNs. Data from this program will be applied to efforts to place constraints on the sizes and geometries of the AGN broad-line regions by the method of reverberation mapping. The BVRI images were obtained with an Axiom 2048x2048 zero-defect CCD array. The observing run was hampered by frequent scattered clouds, limiting the accuracy with which magnitudes could be calibrated. However, the wide field (9.38x9.38 arcmin) of the CCD array encompasses several comparison stars in each object field, and permits differential photometry to be performed even under relatively poor sky conditions. Partial support of this work by the National Science Foundation, through the Research Experience for Undergraduates Program, and by the Valdosta State University Center on Faculty Development and Instructional Improvement, is gratefully acknowledged.

  17. A Hidden Radio Halo in the Galaxy Cluster A1682?

    Indian Academy of Sciences (India)

    High sensitivity observations of radio halos in galaxy clusters at frequencies ≤ 330 MHz are still relatively rare, and very little is known compared to the classical 1.4 GHz images. The few radio halos imaged down to 150–240 MHz show a considerable spread in size, morphology and spectral properties. All clusters ...

  18. Continuum Lowering -- A New Perspective

    CERN Document Server

    Crowley, B J B

    2013-01-01

    What is meant by continuum lowering and ionisation potential depression (IPD) in a Coulomb system depends very much upon what question is being asked and whether it relates to equilibrium (equation-of-state) phenomena or non-equilibrium dynamical processes like photoionisation. It is shown that these scenarios are characterised by different values of the IPD. In the former, the ionisation potential of an atom embedded in matter is the difference in the free energy of the many-body system between states of thermodynamic equilibrium differing by the ionisation state of just one atom. Typically, this energy is less than that required to ionise the same atom in vacuo. Probably, the best known example of the IPD determined this way is that given by Stewart and Pyatt (SP). However, it is a common misconception that this formula should apply to the energy of a photon causing photoionisation - a local adiabatic process that occurs on timescales far too short to allow the final state to come into equilibrium, and addi...

  19. Continuum mechanics elasticity, plasticity, viscoelasticity

    CERN Document Server

    Dill, Ellis H

    2006-01-01

    FUNDAMENTALS OF CONTINUUM MECHANICSMaterial ModelsClassical Space-TimeMaterial BodiesStrainRate of StrainCurvilinear Coordinate SystemsConservation of MassBalance of MomentumBalance of EnergyConstitutive EquationsThermodynamic DissipationObjectivity: Invariance for Rigid MotionsColeman-Mizel ModelFluid MechanicsProblems for Chapter 1BibliographyNONLINEAR ELASTICITYThermoelasticityMaterial SymmetriesIsotropic MaterialsIncompressible MaterialsConjugate Measures of Stress and StrainSome Symmetry GroupsRate Formulations for Elastic MaterialsEnergy PrinciplesGeometry of Small DeformationsLinear ElasticitySpecial Constitutive Models for Isotropic MaterialsMechanical Restrictions on the Constitutive RelationsProblems for Chapter 2BibliographyLINEAR ELASTICITYBasic EquationsPlane StrainPlane StressProperties of SolutionsPotential EnergySpecial Matrix NotationThe Finite Element Method of SolutionGeneral Equations for an Assembly of ElementsFinite Element Analysis for Large DeformationsProblems for Chapter 3Bibliograph...

  20. A tomographic UV-sheet scanning technique for producing 3D fluorescence images of x-ray beams in a radio-fluorogenic gel

    NARCIS (Netherlands)

    Yao, T.; Gasparini, A.; de Haas, M.P.; Luthjens, L.H.; Denkova, A.G.; Warman, J.M.

    2017-01-01

    In this work a 40 mm cube of an optically clear, radio-fluorogenic gel composed of partially-polymerized tertiary-butyl acrylate and maleimido-pyrene (~0.01%) is irradiated with orthogonally-crossed, 10 mm square and round, 200 kVp x-ray beams. A thin sheet of UV light is produced between two

  1. Impact of cognitive radio on radio astronomy

    NARCIS (Netherlands)

    Bentum, Marinus Jan; Boonstra, A.J.; Baan, W.A.

    2010-01-01

    The introduction of new communication techniques requires an increase in the efficiency of spectrum usage. Cognitive radio is one of the new techniques that fosters spectrum efficiency by using unoccupied frequency spectrum for communications. However, cognitive radio will increase the transmission

  2. Radio Stalin as an example of the Czech pirate radio

    OpenAIRE

    Prágrová, Šárka

    2017-01-01

    Diploma thesis "Radio Stalin as an example of Czech piracy radio broadcast" is aimed to complexly present radio station Radio Stalin which was broadcasting in October 1990 in Prague. Radio Stalin is presented in the context of events of that time and related changes in politics, economy, society and media and in the context of piracy radio broadcast. First of all the emphasis is put on media transformation and changes in legislative framework of radio broadcasting after 1989. Radio Stalin is ...

  3. OBSERVATIONAL STUDY OF THE CONTINUUM AND WATER MASER EMISSION IN THE IRAS 19217+1651 REGION

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Esnard, T.; Trinidad, M. A. [Departamento de Astronomia, Universidad de Guanajuato, Apdo Postal 144, Guanajuato, GTO, Mexico CP 36000 (Mexico); Migenes, V., E-mail: tatiana@iga.cu, E-mail: trinidad@astro.ugto.mx, E-mail: vmigenes@byu.edu [Department of Physics and Astronomy, Brigham Young University, ESC-N145, Provo, UT 84602 (United States)

    2012-12-20

    We report interferometric observations of the high-mass star-forming region IRAS 19217+1651. We observed the radio continuum (1.3 cm and 3.6 cm) and water maser emission using the Very Large Array (VLA-EVLA) in transition mode (configuration A). Two radio continuum sources were detected at both wavelengths, I19217-A and I19217-B. In addition, 17 maser spots were observed distributed mainly in two groups, M1 and M2, and one isolated maser. This latter could be indicating the relative position of another continuum source which we did not detect. The results indicate that I19217-A appears to be consistent with an ultracompact H II region associated with a zero-age main-sequence B0-type star. Furthermore, the 1.3 cm continuum emission of this source suggests a cometary morphology. In addition, I19217-B appears to be an H II region consisting of at least two stars, which may be contributing to its complex structure. It was also found that the H{sub 2}O masers of the group M1 are apparently associated with the continuum source I19217-A. These are tracing motions which are not gravitationally bound according to their spatial distribution and kinematics. They also seem to be describing outflows in the direction of the elongated cometary region. On the other hand, the second maser group, M2, could be tracing the base of a jet. Finally, infrared data from Spitzer, Midcourse Space Experiment, and IRIS show that IRAS 19217+1651 is embedded inside a large open bubble, like a broken ring, which possibly has affected the morphology of the cometary H II region observed at 1.3 cm.

  4. Continuum mechanics of single-substance bodies

    CERN Document Server

    Eringen, A Cemal

    1975-01-01

    Continuum Physics, Volume II: Continuum Mechanics of Single-Substance Bodies discusses the continuum mechanics of bodies constituted by a single substance, providing a thorough and precise presentation of exact theories that have evolved during the past years. This book consists of three parts-basic principles, constitutive equations for simple materials, and methods of solution. Part I of this publication is devoted to a discussion of basic principles irrespective of material geometry and constitution that are valid for all kinds of substances, including composites. The geometrical notions, k

  5. Leaving home [radio drama

    OpenAIRE

    Lawrence, Conan

    2014-01-01

    A 50 minute Radio Drama tracing the stories of Amy, Edie and Barnard Beechey as they prepare for the First World War and the changes it brings to their lives. Broadcast on BBC Radio Lincolnshire, 4th August, 2014.

  6. Fast Radio Bursts

    Indian Academy of Sciences (India)

    28

    FRBs) which were first discovered a decade ago. Following an introduction to radio transients in general, including pulsars and Rotating Radio. Transients, we discuss the discovery of FRBs. We then discuss FRB follow-up observations in the ...

  7. MARS PATHFINDER RADIO TRACKING

    Data.gov (United States)

    National Aeronautics and Space Administration — The Mars Pathfinder (MPF) Radio Science (RS) data archive contains both raw radio tracking data collected during the surface lifetime of the MPF Lander and results...

  8. Frontiers of Radio Astronomy in the 2020s: The Next Generation Very Large Array

    Science.gov (United States)

    Murphy, Eric Joseph; ngVLA Project Office, ngVLA Science and Technical Advisory Councils, ngVLA Science Working Groups

    2018-01-01

    This talk will describe the current community-driven science goals, design, and planning status of a future large centimeter radio array: the ‘Next Generation Very Large Array’ (ngVLA). The ngVLA is being developed to observe at wavelengths between ALMA at submm wavelengths, and the future SKA-1 at few centimeter and longer wavelengths, opening a new window on the Universe through ultra-sensitive imaging of thermal line and continuum emission down to milliarcsecond resolution, and unprecedented broad band continuum polarimetric imaging of non-thermal processes. The current design for the array includes 10x more effective collecting area and 10x higher spatial resolution than the current JVLA or ALMA, carefully optimized for operation in the frequency range 10GHz to 50GHz, while still delivering world-leading sensitivity over the entire 1.2GHz to 116 GHz spectrum.With this array, new frontiers in modern astronomy can be reached, including direct imaging and chemical analysis of planet formation in the terrestrial-zone of nearby stars, studies of dust-obscured star formation and the cosmic baryon cycle down to pc-scales in the local Universe, and detailed imaging of molecular gas and galaxy formation into the epoch of reionization. Novel techniques for exploring temporal phenomena on timescales from milliseconds to years will also be implemented. The ngVLA will be situated in the desert southwest of the United States, centered on the current JVLA infrastructure, with multiple antennas anticipated in states/regions adjacent to NM, and in northern Mexico.A recently formed Project Office is working closely with the U.S. and international research community to design the array, and plan its construction beginning mid next decade. Recent significant funding for design and development brought forward by the NSF will enable detailed science case development and technology prototyping/risk reduction before the next U.S astronomy Decadal Survey.

  9. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... imaging (MRI) uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of ... the body being imaged, send and receive radio waves, producing signals that are detected by the coils. ...

  10. Hydra A at Low Radio Frequencies

    National Research Council Canada - National Science Library

    Lane, W. M; Clarke, T. E; Taylor, G. B; Perley, R. A; Kassim, N. E

    2004-01-01

    We present new, low-frequency images of the powerful FR I radio galaxy Hydra A (3C 218). Images were made with the Very Large Array at frequencies of 1415, 330, and 74 MHz, with resolutions on the order of 20...

  11. Geometric continuum mechanics and induced beam theories

    CERN Document Server

    R Eugster, Simon

    2015-01-01

    This research monograph discusses novel approaches to geometric continuum mechanics and introduces beams as constraint continuous bodies. In the coordinate free and metric independent geometric formulation of continuum mechanics as well as for beam theories, the principle of virtual work serves as the fundamental principle of mechanics. Based on the perception of analytical mechanics that forces of a mechanical system are defined as dual quantities to the kinematical description, the virtual work approach is a systematic way to treat arbitrary mechanical systems. Whereas this methodology is very convenient to formulate induced beam theories, it is essential in geometric continuum mechanics when the assumptions on the physical space are relaxed and the space is modeled as a smooth manifold. The book addresses researcher and graduate students in engineering and mathematics interested in recent developments of a geometric formulation of continuum mechanics and a hierarchical development of induced beam theories.

  12. Defining and testing a granular continuum element

    OpenAIRE

    Rycroft, Chris H.; Kamrin, Ken; Bazant, Martin Z.

    2008-01-01

    Continuum mechanics relies on the fundamental notion of a mesoscopic volume "element" in which properties averaged over discrete particles obey deterministic relationships. Recent work on granular materials suggests a continuum law may be inapplicable, revealing inhomogeneities at the particle level, such as force chains and slow cage breaking. Here, we analyze large-scale Discrete-Element Method (DEM) simulations of different granular flows and show that a "granular element" can indeed ...

  13. Ham radio for dummies

    CERN Document Server

    Silver, H Ward

    2013-01-01

    An ideal first step for learning about ham radio Beyond operating wirelessly, today's ham radio operators can transmit data and pictures; use the Internet, laser, and microwave transmitters; and travel to places high and low to make contact. This hands-on beginner guide reflects the operational and technical changes to amateur radio over the past decade and provides you with updated licensing requirements and information, changes in digital communication (such as the Internet, social media, and GPS), and how to use e-mail via radio. Addresses the critical use of ham radio for replacing downe

  14. WISE J233237.05-505643.5: A Double-Peaked Broad-Lined AGN with Spiral-Shaped Radio Morphology

    Science.gov (United States)

    Tsai, Chao Wei; Jarrett, Thomas H.; Stern, Daniel; Emonts, Bjorn; Barrows, R. Scott; Assef, Roberto J.; Norris, Ray P.; Eisenhardt, Peter R. M.; Lonsdale, Carol; Blain, Andrew W.; hide

    2013-01-01

    We present radio continuum mapping, optical imaging and spectroscopy of the newly discovered double-peaked broad-lined AGN WISE J233237.05-505643.5 at redshift z = 0.3447. This source exhibits an FR-I and FR-II hybrid-morphology, characterized by bright core, jet, and Doppler-boosted lobe structures in ATCA continuum maps at 1.5, 5.6, and 9 GHz. Unlike most FR-II objects, W2332-5056 is hosted by a disk-like galaxy. The core has a projected 5" linear radio feature that is perpendicular to the curved primary jet, hinting at unusual and complex activity within the inner 25 kpc. The multi-epoch optical-near-IR photometric measurements indicate significant variability over a 3-20 year baseline from the AGN component. Gemini-South optical data shows an unusual double-peaked emission-line features: the centroids of the broad-lined components of H-alpha and H-beta are blueshifted with respect to the narrow lines and host galaxy by approximately 3800 km/s. We examine possible cases which involve single or double supermassive black holes in the system, and discuss required future investigations to disentangle the mystery nature of this system.

  15. Radiography of Spanish Radio

    Directory of Open Access Journals (Sweden)

    Dra. Emma Rodero Antón

    2007-01-01

    Full Text Available In its eighty years of existence, radio has been always characterized to adapt to the social, cultural and technological transformations. Thus it has been until this moment. Nevertheless, some years ago, the authors and professionals of this medium have been detecting a stagnation that affects to its structure. At a time in continuous technological evolution, radio demands a deep transformation. For that reason, from the conviction of which the future radio, public and commercial, will necessarily have to renew itself, in this paper we establish ten problems and their possible solutions to the radio crisis in order to draw an x-ray of radio in Spain. Radio has future, but it is necessary to work actively by it. That the radio continues being part of sound of our life, it will depend on the work of all: companies, advertisers, professionals, students, investigators and listeners.

  16. Radio Galaxy Zoo: cosmological alignment of radio sources

    Science.gov (United States)

    Contigiani, O.; de Gasperin, F.; Miley, G. K.; Rudnick, L.; Andernach, H.; Banfield, J. K.; Kapińska, A. D.; Shabala, S. S.; Wong, O. I.

    2017-11-01

    We study the mutual alignment of radio sources within two surveys, Faint Images of the Radio Sky at Twenty-centimetres (FIRST) and TIFR GMRT Sky Survey (TGSS). This is done by producing two position angle catalogues containing the preferential directions of respectively 30 059 and 11 674 extended sources distributed over more than 7000 and 17 000 deg2. The identification of the sources in the FIRST sample was performed in advance by volunteers of the Radio Galaxy Zoo (RGZ) project, while for the TGSS sample it is the result of an automated process presented here. After taking into account systematic effects, marginal evidence of a local alignment on scales smaller than 2.5 deg is found in the FIRST sample. The probability of this happening by chance is found to be less than 2 per cent. Further study suggests that on scales up to 1.5 deg the alignment is maximal. For one third of the sources, the RGZ volunteers identified an optical counterpart. Assuming a flat Λ cold dark matter cosmology with Ω _m = 0.31, Ω _Λ = 0.69, we convert the maximum angular scale on which alignment is seen into a physical scale in the range [19, 38] Mpc h_{70}^{-1}. This result supports recent evidence reported by Taylor and Jagannathan of radio jet alignment in the 1.4 deg2 ELAIS N1 field observed with the Giant Metrewave Radio Telescope. The TGSS sample is found to be too sparsely populated to manifest a similar signal.

  17. Multi Texture Analysis of Colorectal Cancer Continuum Using Multispectral Imagery.

    Directory of Open Access Journals (Sweden)

    Ahmad Chaddad

    Full Text Available This paper proposes to characterize the continuum of colorectal cancer (CRC using multiple texture features extracted from multispectral optical microscopy images. Three types of pathological tissues (PT are considered: benign hyperplasia, intraepithelial neoplasia and carcinoma.In the proposed approach, the region of interest containing PT is first extracted from multispectral images using active contour segmentation. This region is then encoded using texture features based on the Laplacian-of-Gaussian (LoG filter, discrete wavelets (DW and gray level co-occurrence matrices (GLCM. To assess the significance of textural differences between PT types, a statistical analysis based on the Kruskal-Wallis test is performed. The usefulness of texture features is then evaluated quantitatively in terms of their ability to predict PT types using various classifier models.Preliminary results show significant texture differences between PT types, for all texture features (p-value < 0.01. Individually, GLCM texture features outperform LoG and DW features in terms of PT type prediction. However, a higher performance can be achieved by combining all texture features, resulting in a mean classification accuracy of 98.92%, sensitivity of 98.12%, and specificity of 99.67%.These results demonstrate the efficiency and effectiveness of combining multiple texture features for characterizing the continuum of CRC and discriminating between pathological tissues in multispectral images.

  18. The Completeness and Reliability of Threshold and False-discovery Rate Source Extraction Algorithms for Compact Continuum Sources

    Science.gov (United States)

    Huynh, M. T.; Hopkins, A.; Norris, R.; Hancock, P.; Murphy, T.; Jurek, R.; Whiting, M.

    2012-12-01

    The process of determining the number and characteristics of sources in astronomical images is so fundamental to a large range of astronomical problems that it is perhaps surprising that no standard procedure has ever been defined that has well-understood properties with a high degree of statistical rigour on completeness and reliability. The Evolutionary Map of the Universe (EMU) survey with the Australian Square Kilometre Array Pathfinder (ASKAP), a continuum survey of the Southern Hemisphere up to declination +30°, aims to utilise an automated source identification and measurement approach that is demonstrably optimal, to maximise the reliability, utility and robustness of the resulting radio source catalogues. A key stage in source extraction methods is the background estimation (background level and noise level) and the choice of a threshold high enough to reject false sources, yet not so high that the catalogues are significantly incomplete. In this analysis, we present results from testing the SExtractor, Selavy (Duchamp), and sfind source extraction tools on simulated data. In particular, the effects of background estimation, threshold and false-discovery rate settings are explored. For parameters that give similar completeness, we find the false-discovery rate method employed by sfind results in a more reliable catalogue compared to the peak threshold methods of SExtractor and Selavy.

  19. Radio sciences and disaster management

    Science.gov (United States)

    Tanzi, Tullio Joseph; Lefeuvre, François

    2010-01-01

    Radio communication and observation services are critical at all levels of disaster management. Among the programmes to be introduced to reduce the impact of natural and human induced disasters, potential transfers from basic research in radio science to research in disaster management are examined. Two specific aspects are studied: (i) the transfer of image processing techniques, developed in other contexts, to risk management; and (ii) the use of knowledge gathered on the effects of variations in the space environment on trans-ionospheric propagation, to gauge the interest of integrating those effects into the exploitation of communications and observation systems. Four families of image processing techniques are shown to be particularly useful to the disaster manager: zoning, counting of objects, roads and network detection, and damage assessment resulting from a series of different radiometric and geometric methods. A brief review of the effects of ionospheric variations on radio propagation up to a few GHz shows both the potential impacts of those variations on communication systems and the importance of introducing ionospheric corrections into several observation services.

  20. THE DISCOVERY OF A YOUNG RADIO GALAXY AT Z = 2.390 - PROBING INITIAL STAR FORMATION AT Z-LESS-THAN-APPROXIMATELY-EQUAL-TO-3.0

    NARCIS (Netherlands)

    WINDHORST, RA; BURSTEIN, D; MATHIS, DF; NEUSCHAEFER, LW; BERTOLA, F; BUSON, LM; KOO, DC; MATTHEWS, K; BARTHEL, PD; CHAMBERS, KC

    1991-01-01

    We present the discovery of a weak radio galaxy from the Leiden Berkeley Deep Survey at a redshift of 2.390, the faint optical and IR counterpart of the steep-spectrum, compact radio source 53W002. Its lambda-dependent optical continuum morphology is compact with linear size approximately 10-35 kpc

  1. Prioritizing partners across the continuum.

    Science.gov (United States)

    Maly, Mary Beth; Lawrence, Susan; Jordan, M Kim; Davies, William J; Weiss, Michael J; Deitrick, Lynn; Salas-Lopez, Debbie

    2012-11-01

    With the advent of accountable care organizations, bundled payments, value-based purchasing, and penalties for preventable hospital readmission, tight connections and collaboration across the care continuum will become critical to achieve successful patient outcomes and to reduce the cost of care delivery. Lehigh Valley Health Network (LVHN), the largest provider of health services in eastern Pennsylvania, set out on a journey to build collaborative relationships with skilled nursing facilities (SNFs) in their eastern Pennsylvania community. LVHN desired SNF partners with mutual interests in improving quality of care and lowering costs of delivery where possible. Recognizing that not all SNFs are alike, LVHN developed a Collaborative Partner Prioritization Tool to assess and prioritize skilled nursing facilities in an effort to determine those that would make the best collaborators. SNFs were reviewed based on their volume of mutual patients, quality of care delivery, and their perceived willingness to align with LVHN. Six variables were used to assess these facilities, including (1) patient discharge destination volume by SNF; (2) 30-day all-cause readmission rate to an LVHN hospital; (3) Medicare's Nursing Home Compare 5-Star Overall Rating; (4) the health network affiliation of the SNF's medical director; (5) the level of LVHN-employed or -affiliated physician presence at the SNF; and (6) the SNF's current participation in LVHN-sponsored programs and meetings. Through use of the Collaborative Partner Prioritization Tool, it was discovered that roughly 70% of LVHN patients who required skilled nursing care following their inpatient stay received care at 1 of 20 SNFs. Of these, 5 facilities performed well on the 6-variable assessment, deeming them the "Tier 1 Facilities" to initially focus collaborative efforts. LVHN has strategically deployed physician resources and has increased physician presence at these "Tier 1 SNFs." These facilities have also gained remote

  2. Senior radio listeners

    DEFF Research Database (Denmark)

    Blaakilde, Anne Leonora

    media platforms, not the least when listening to radio. The elder generation is no exception from this. Recently, for instance, the Danish public broadcast DR has carried out an exodus of programmes targeted for the senior segment. These programmes are removed from regular FM and sent to DAB receivers......Radiobroadcasting and the hardware materialization of radio have during the 20th century changed significantly, which means that senior radio listeners have travelled along with this evolution from large, impressive radio furnitures to DAB and small, wireless, mobile devices, and from grave...... and solemn radio voices to lightharted, laughing and chatting speakers. Senior radio listerners have experienced the development and refinements of technique, content and genres. It is now expected of all media users that they are capable of crossing media, combining, juggling and jumping between various...

  3. Properties of Lya Emitters Around the Radio Galaxy MRC 0316-257

    Energy Technology Data Exchange (ETDEWEB)

    Venemans, B; Rottgering, H; Miley, G; Kurk, J; De Breuck, C; van Breugel, W; Carilli, C; Ford, H; Heckman, T; Pentericci, L; McCarthy, P

    2004-08-12

    Observations of the radio galaxy MRC 0316-257 at z = 3.13 and the surrounding field are presented. Using narrow- and broad-band imaging obtained with the VLT*, 92 candidate Ly{alpha} emitters with a rest-frame equivalent width of > 15 AngstromS were selected in a {approx} 7{prime} x 7{prime} field around the radio galaxy. Spectroscopy of 40 candidate emitters resulted in the discovery of 33 emission line galaxies of which 31 are Ly{alpha} emitters with redshifts similar to that of the radio galaxy, while the remaining two galaxies turned out to be [{omicron} II] emitters. The Ly{alpha} profiles had widths (FWHM) corresponding to 120-800 kms{sup -1},with a median of 260 kms{sup -1}. Where the signal-to-noise spectra was large enough, the Ly{alpha} profiles are found to be asymmetric, with apparent absorption troughs blueward of the profile peaks, indicative of absorption along the line of sight of an {Eta}{Iota} mass of 1-5000 {mu}{circle_dot}. Besides that of the radio galaxy and one of the emitters that is an QSO, the continuum of the emitters is faint, with luminosities ranging from 1.3 L{sub *} to < 0.03 L{sub *}.The colors of the confirmed emitters are, on average, very blue. The median UV continuum slope is {beta}=-1.65, bluer than the average slope of LBGs with Ly{alpha} emitters is 2.6 {Mu}{circle_dot}{sup -1} as measured by the Ly{alpha} emission line or < 3.9 {Mu}{circle_dot}{sup -1} as measured by the UV continuum. The properties of the Ly{alpha} galaxies (faint, blue and small) are consistent with young star forming galaxies which are nearly dust free. The density of Ly{alpha} emitting galaxies in the field around MRC 0316-257 is a factor of 3.3{sup +0.5}{sub -0.4} larger compared with the density of Ly{alpha} emitters at that redshift. The velocity distribution of the spectroscopically confirmed emitters has a dispersion of 640 km s{sup -1}, corresponding to a FWHM of 1510 km s{sup -1}, which is substantially smaller than the width of the narrow

  4. The Radio/Optical Morphology of Micro-Jansky Radio Sources

    Science.gov (United States)

    Fomalont, E. B.; Kellermann, K. I.; Cowie, L. L.; Barger, A. J.

    2002-12-01

    We have observed the SSA13 field (RA=13 23, DEC=42 38) using the VLA. At 1.4 GHz the rms noise is 5.0 μ Jy with resolution 1.8'', at 8.4 GHz the rms noise is 1.5 μ Jy with a resolution of 3.0''. Optical images at R-band and Z-band with 1.1'' seeing were obtained from the Subaru telescope. Over 900 radio sources were detected (528 in the complete sample) and the optical/radio registration 95% of the radio sources. The radio/optical morphological properties of the sources are sorted into a small number of classifications and these properties are compared. Our main conclusions are: (1) About half of the radio sources are associated with a relatively isolated galaxy; most other identifications are with binary systems. (2) Only 7 extended AGN (>5'') are found. (3) At Z-band, 8% of the sources are fainter than 26 mag. (4) The slope of the differential radio count is -2.3 with a density of 2.0 sources (amin)-2 with a flux density >27.5 μ Jy. (5) The average radio angular size is 1.35'', but very few sources are larger than 5''. (6) The radio orientation is often correlated with the galaxy identification or binary system orientation. Two correlations in these data suggest that most sources are associated with distant galaxies dominated by starburst activity. (1) The radio sources with angular size >1'' show an Infrared/radio correlation, whereas smaller-diameter sources do not; and (2) The radio spectral index steepens for sources weak then 100 μ Jy, suggesting an even lower proportion of AGN at the fainter observed levels.

  5. STEM on the radio

    Science.gov (United States)

    Showstack, Randy

    2011-10-01

    Looking for an Internet radio station focusing on programing about science, technology, engineering, and math (STEM)? The U.S. National Science Foundation (NSF) announced on 26 September the launch of Science360 Radio, which it says is the first Internet radio stream dedicated to STEM programing. Science360 includes more than 100 radio shows and podcasts that are available on the Web as well as on iPhone and Android devices. The shows originate from a variety of sources, including NSF, other U.S. government agencies, science organizations, universities, and media outlets. For more information, see http://science360.gov/files/.

  6. Hyperbolic conservation laws in continuum physics

    CERN Document Server

    Dafermos, Constantine M

    2016-01-01

    This is a masterly exposition and an encyclopedic presentation of the theory of hyperbolic conservation laws. It illustrates the essential role of continuum thermodynamics in providing motivation and direction for the development of the mathematical theory while also serving as the principal source of applications. The reader is expected to have a certain mathematical sophistication and to be familiar with (at least) the rudiments of analysis and the qualitative theory of partial differential equations, whereas prior exposure to continuum physics is not required. The target group of readers would consist of (a) experts in the mathematical theory of hyperbolic systems of conservation laws who wish to learn about the connection with classical physics; (b) specialists in continuum mechanics who may need analytical tools; (c) experts in numerical analysis who wish to learn the underlying mathematical theory; and (d) analysts and graduate students who seek introduction to the theory of hyperbolic systems of conser...

  7. Stiffness Control of Surgical Continuum Manipulators.

    Science.gov (United States)

    Mahvash, Mohsen; Dupont, Pierre E

    2011-04-01

    This paper introduces the first stiffness controller for continuum robots. The control law is based on an accurate approximation of a continuum robot's coupled kinematic and static force model. To implement a desired tip stiffness, the controller drives the actuators to positions corresponding to a deflected robot configuration that produces the required tip force for the measured tip position. This approach provides several important advantages. First, it enables the use of robot deflection sensing as a means to both sense and control tip forces. Second, it enables stiffness control to be implemented by modification of existing continuum robot position controllers. The proposed controller is demonstrated experimentally in the context of a concentric tube robot. Results show that the stiffness controller achieves the desired stiffness in steady state, provides good dynamic performance, and exhibits stability during contact transitions.

  8. A Zynq-based Cluster Cognitive Radio

    OpenAIRE

    Rooks, Kurtis M.

    2014-01-01

    Traditional hardware radios provide very rigid solutions to radio problems. Intelligent software defined radios, also known as cognitive radios, provide flexibility and agility compared to hardware radio systems. Cognitive radios are well suited for radio applications in a changing radio frequency environment, such as dynamic spectrum access. In this thesis, a cognitive radio is demonstrated where the system self reconfigures to dem...

  9. Planck intermediate results. XLV. Radio spectra of northern extragalactic radio sources

    Science.gov (United States)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Aller, H. D.; Aller, M. F.; Arnaud, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Burigana, C.; Calabrese, E.; Catalano, A.; Chiang, H. C.; Christensen, P. R.; Clements, D. L.; Colombo, L. P. L.; Couchot, F.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Ducout, A.; Dupac, X.; Efstathiou, G.; Elsner, F.; Eriksen, H. K.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gruppuso, A.; Gurwell, M. A.; Hansen, F. K.; Harrison, D. L.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Hildebrandt, S. R.; Hobson, M.; Hornstrup, A.; Hovatta, T.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Järvelä, E.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leonardi, R.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Maris, M.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; Max-Moerbeck, W.; Meinhold, P. R.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Mingaliev, M.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Nati, F.; Natoli, P.; Nieppola, E.; Noviello, F.; Novikov, D.; Novikov, I.; Pagano, L.; Pajot, F.; Paoletti, D.; Partridge, B.; Pasian, F.; Pearson, T. J.; Perdereau, O.; Perotto, L.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Pratt, G. W.; Ramakrishnan, V.; Rastorgueva-Foi, E. A.; S Readhead, A. C.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Richards, J. L.; Ristorcelli, I.; Rocha, G.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Savelainen, M.; Savini, G.; Scott, D.; Sotnikova, Y.; Stolyarov, V.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tammi, J.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tornikoski, M.; Tristram, M.; Tucci, M.; Türler, M.; Valenziano, L.; Valiviita, J.; Valtaoja, E.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L. A.; Wehrle, A. E.; Wehus, I. K.; Yvon, D.; Zacchei, A.; Zonca, A.

    2016-12-01

    Continuum spectra covering centimetre to submillimetre wavelengths are presented for a northern sample of 104 extragalactic radio sources, mainly active galactic nuclei, based on four-epoch Planck data. The nine Planck frequencies, from 30 to 857 GHz, are complemented by a set of simultaneous ground-based radio observations between 1.1 and 37 GHz. The single-survey Planck data confirm that the flattest high-frequency radio spectral indices are close to zero, indicating that the original accelerated electron energy spectrum is much harder than commonly thought, with power-law index around 1.5 instead of the canonical 2.5. The radio spectra peak at high frequencies and exhibit a variety of shapes. For a small set of low-z sources, we find a spectral upturn at high frequencies, indicating the presence of intrinsic cold dust. Variability can generally be approximated by achromatic variations, while sources with clear signatures of evolving shocks appear to be limited to the strongest outbursts.

  10. Continuum mechanics concise theory and problems

    CERN Document Server

    Chadwick, P

    1998-01-01

    Written in response to the dearth of practical and meaningful textbooks in the field of fundamental continuum mechanics, this comprehensive treatment offers students and instructors an immensely useful tool. Its 115 solved problems and exercises not only provide essential practice but also systematically advance the understanding of vector and tensor theory, basic kinematics, balance laws, field equations, jump conditions, and constitutive equations.Readers follow clear, formally precise steps through the central ideas of classical and modern continuum mechanics, expressed in a common, effici

  11. I. S. Shklovsky and Low-Frequency Radio Astronomy

    Science.gov (United States)

    Konovalenko, A. A.

    2017-03-01

    Purpose: Proving of the high astrophysical significance of the low-frequency radio astronomy (decameter and adjacent hectometer and meter wavelengths), demonstration of the priority results of the Ukrainian low-frequency radio astronomy as well as significant contribution of I. S. Shklovsky to its development. Design/methodology/approach: The requirements to characteristics of high efficiency radio telescopes UTR-2, URAN, GURT and to sensitive and interference immune observational methods at low frequencies are formulated by using the theoretical analysis and astrophysical predictions including those I. S. Shklovsky’s. Findings: New generation radio telescopes UTR-2, URAN, GURT are created and modernized. New observational methods at low frequencies are introduced. Large-scale investigations of the Solar system, Galaxy and Methagalaxy are carried out. They have allowed to detect new objects and phenomena for the continuum, monochromatic, pulse and sporadic cosmic radio emission. The role of I. S. Shklovsky in the development of many low-frequency radio astronomy directions is noted, too. Conclusions: The unique possibilities of the low-frequency radio astronomy which gives new information about the Universe, inaccessible with the other astrophysical methods, are shown. The progress of the low-frequency radio astronomy opens the impressive possibilities for the future. It includes modernization of the largest radio telescopes UTR-2, URAN, NDA and creation of new instruments GURT, NenuFAR, LOFAR, LWA, MWA, SKA as well as making multi-antenna and ground-space experiments. The contribution of outstanding astrophysicist of the XX century I. S. Shklovsky to this part of actual astronomical science is evident, claiming for attention and will never be forgotten.

  12. Mentorship: The Education-Research Continuum

    Energy Technology Data Exchange (ETDEWEB)

    Correll, D

    2008-05-29

    Mentoring of science students stems naturally from the intertwined link between science education and science research. In fact, the mentoring relationship between a student and a scientist may be thought of analogically as a type of double helix forming the 'DNA' that defines the blueprint for the next generation of scientists. Although this analogy would not meet the rigorous tests commonly used for exploring the natural laws of the universe, the image depicted does capture how creating and sustaining the future science workforce benefits greatly from the continuum between education and research. The path science students pursue from their education careers to their research careers often involves training under an experienced and trusted advisor, i.e., a mentor. For many undergraduate science students, a summer research internship at a DOE National Laboratory is one of the many steps they will take in their Education-Research Continuum. Scientists who choose to be mentors share a commitment for both science education and science research. This commitment is especially evident within the research staff found throughout the Department of Energy's National Laboratories. Research-based internship opportunities within science, technology, engineering and mathematics (STEM) exist at most, if not all, of the Laboratories. Such opportunities for students are helping to create the next generation of highly trained professionals devoted to the task of keeping America at the forefront of scientific innovation. 'The Journal of Undergraduate Research' (JUR) provides undergraduate interns the opportunity to publish their scientific innovation and to share their passion for education and research with fellow students and scientists. The theme of this issue of the JUR (Vol. 8, 2008) is 'Science for All'. Almost 20 years have passed since the American Association for the Advancement of Science published its 1989 report, 'Science for All

  13. Radio stars observed in the LAMOST spectral survey

    Science.gov (United States)

    Zhang, Li-Yun; Yue, Qiang; Lu, Hong-Peng; Han, Xian-Ming L.; Zhang, Yong; Shi, Jian-Rong; Wang, Yue-Fei; Hou, Yong-Hui; Zi-Huang, Cao

    2017-09-01

    Radio stars have attracted astronomers’ attention for several decades. To better understand the physics behind stellar radio emissions, it is important to study their optical behaviors. The LAMOST survey provides a large database for researching stellar spectroscopic properties of radio stars. In this work, we concentrate on their spectroscopic properties and infer physical properties from their spectra, such as stellar activity and variability. We mined big data from the LAMOST spectral survey Data Release 2 (DR2), published on 2016 June 30, by cross-matching them with radio stars from FIRST and other surveys. We obtained 783 good stellar spectra with high signal to noise ratio for 659 stars. The criteria for selection were positional coincidence within 1.5‧‧ and LAMOST objects classified as stars. We calculated the equivalent widths (EWs) of the Ca ii H&K, Hδ, Hγ, Hβ, Hα and Ca ii IRT lines by integrating the line profiles. Using the EWs of the Hα line, we detected 147 active stellar spectra of 89 objects having emissions above the Hα continuum. There were also 36 objects with repeated spectra, 28 of which showed chromospheric activity variability. Furthermore, we found 14 radio stars emitting noticeably in the Ca ii IRT lines. The low value of the EW8542/EW8498 ratio for these 14 radio stars possibly alludes to chromospheric plage regions.

  14. Boom Booom Net Radio

    DEFF Research Database (Denmark)

    Grimshaw, Mark Nicholas; Yong, Louisa; Dobie, Ian

    1999-01-01

    of an existing Internet radio station; Boom Booom Net Radio. Whilst necessity dictates some use of technology-related terminology, wherever possible we have endeavoured to keep such jargon to a minimum and to either explain it in the text or to provide further explanation in the appended glossary....

  15. Radio Graceful Hamming Graphs

    Directory of Open Access Journals (Sweden)

    Niedzialomski Amanda

    2016-11-01

    Full Text Available For k ∈ ℤ+ and G a simple, connected graph, a k-radio labeling f : V (G → ℤ+ of G requires all pairs of distinct vertices u and v to satisfy |f(u − f(v| ≥ k + 1 − d(u, v. We consider k-radio labelings of G when k = diam(G. In this setting, f is injective; if f is also surjective onto {1, 2, . . . , |V (G|}, then f is a consecutive radio labeling. Graphs that can be labeled with such a labeling are called radio graceful. In this paper, we give two results on the existence of radio graceful Hamming graphs. The main result shows that the Cartesian product of t copies of a complete graph is radio graceful for certain t. Graphs of this form provide infinitely many examples of radio graceful graphs of arbitrary diameter. We also show that these graphs are not radio graceful for large t.

  16. Writing for Radio.

    Science.gov (United States)

    Tupper, Marianna S.

    1995-01-01

    Describes a 24-hour commercial radio station simulation class project for eighth-grade language arts. Students wrote their own scripts, chose music and were disc jockeys on their own music and talk shows, and prepared news and traffic reports. Guest speakers from actual commercial radio came in to discuss issues such as advertising, censorship,…

  17. Uranus radio emissions

    Science.gov (United States)

    Kaiser, Michael L.

    An overview of the Voyager 2 Planetary Radio Astronomy instrument observations of the planet Uranus is presented. From these observations, a number of inferences have been made including the rotation period of the interior of the planet and the source locations of several of the radio components.

  18. Ionosphere and Radio Communication

    Indian Academy of Sciences (India)

    The upperionosphere is used for radio communication and navigationas it reflects long, medium, as well as short radio waves. Sincesolar radiation is the main cause of the existence of ionosphere,any variation in the radiations can affect the entireradio communication system. This article attempts to brieflyintroduce the ...

  19. Valuing commercial radio licences

    NARCIS (Netherlands)

    Kerste, M.; Poort, J.; van Eijk, N.

    2015-01-01

    Within the EU regulatory framework, licensees for commercial radio broadcasting may be charged a fee to ensure optimal allocation of scarce resources but not to maximize public revenues. While radio licence renewal occurs in many EU countries, an objective, model-based approach for setting licence

  20. Continuum percolation of isotropically oriented circular cylinders

    Science.gov (United States)

    Sangare, D.; Adler, P. M.

    2009-05-01

    The continuum percolation of circular cylinders has been studied for various values of the aspect ratio b' . The percolation threshold is shown to have a maximum for b'≈2 when the cylinder length is equal to its diameter. Other quantities such as the average intersection volume and the porosity also possess a maximum for this value.

  1. Questioning the continuum: specialization in rock climbing

    Science.gov (United States)

    Sean Nelb; Rudy M. Schuster

    2008-01-01

    Recreation specialization was originally conceived as a behavioral continuum ranging from general to more particular behaviors within an activity. It was assumed that an individual progressed from one subactivity to another in a hierarchical order. In recent years the practicality of such ordering has come under doubt; it may be possible to specialize in individual...

  2. Continuum balances from extended Hamiltonian dynamics.

    Science.gov (United States)

    Giusteri, Giulio G; Podio-Guidugli, Paolo; Fried, Eliot

    2017-06-14

    The classical procedure devised by Irving and Kirkwood in 1950 and completed slightly later by Noll produces counterparts of the basic balance laws of standard continuum mechanics starting from an ordinary Hamiltonian description of the dynamics of a system of material points. Post-1980 molecular dynamics simulations of the time evolution of such systems use extended Hamiltonians such as those introduced by Andersen, Nosé, and Parrinello and Rahman. The additional terms present in these extensions affect the statistical properties of the system so as to capture certain target phenomenologies that would otherwise be beyond reach. We here propose a physically consistent application of the Irving-Kirkwood-Noll procedure to the extended Hamiltonian systems of material points. Our procedure produces balance equations at the continuum level featuring non-standard terms because the presence of auxiliary degrees of freedom gives rise to additional fluxes and sources that influence the thermodynamic and transport properties of the continuum model. Being aware of the additional contributions may prove crucial when designing multiscale computational schemes in which information is exchanged between the atomistic and continuum levels.

  3. Whole Language in Perspective: A Teacher's Continuum.

    Science.gov (United States)

    Christensen, K. Eleanor

    Whole language represents only one of many good concepts about teaching reading to children, but it is not for everybody. Because whole language is a philosophy rather than a specific method, educational practitioners can incorporate different aspects of this philosophy to different degrees. If teachers think of a continuum of theoretical bases…

  4. Design of an environmentally interactive continuum manipulator

    NARCIS (Netherlands)

    Bakker, D.L.; Matsuura, D.; Takeda, Y; Herder, J.L.; Chang, S.H.

    2015-01-01

    Continuum manipulators are high degree of freedom structures that can use their increased degrees of freedom to navigate through an environment with obstacles. This type of manipulator is underactuated, which make them promising for adapting to their environments. However, current research is mainly

  5. Continuum Modeling in the Physical Sciences

    NARCIS (Netherlands)

    Groesen, van E.; Molenaar, J.

    2007-01-01

    Mathematical modeling—the ability to apply mathematical concepts and techniques to real-life systems—has expanded considerably over the last decades, making it impossible to cover all of its aspects in one course or textbook. Continuum Modeling in the Physical Sciences provides an extensive

  6. Parental Involvement to Parental Engagement: A Continuum

    Science.gov (United States)

    Goodall, Janet; Montgomery, Caroline

    2014-01-01

    Based on the literature of the field, this article traces a continuum between parental involvement with schools, and parental engagement with children's learning. The article seeks to shed light on an area of confusion; previous research has shown that different stakeholder groups understand "parental engagement" in different ways.…

  7. The spatial distribution of ultraviolet line and continuum emission in Herbig-Haro objects

    Science.gov (United States)

    Lee, M. G.; Boehm, K. H.; Temple, S. D.; Raga, A. C.; Mateo, M. L.

    1988-01-01

    Archival IUE data and monochromatic CCD images in the optical range are used to compare the spatial distribution of UV and optical emission in HH 1, HH 2, HH 24, HH 32, HH 43, and HH 47. For all six objects, the observed UV radiation is shown to originate in the objects themselves. The results indicate that the C IV and semiforbidden emission-line regions are small. Although the continuum in the IUE short-wavelength range displays a distribution that is broader than that of any measured line emission in the UV or optical range, the continuum distribution in the IUE long-wavelength range is quite narrow.

  8. Evidence that the AGN dominates the radio emission in z ˜ 1 radio-quiet quasars

    Science.gov (United States)

    White, Sarah V.; Jarvis, Matt J.; Kalfountzou, Eleni; Hardcastle, Martin J.; Verma, Aprajita; Cao Orjales, José M.; Stevens, Jason

    2017-06-01

    In order to understand the role of radio-quiet quasars (RQQs) in galaxy evolution, we must determine the relative levels of accretion and star-formation activity within these objects. Previous work at low radio flux densities has shown that accretion makes a significant contribution to the total radio emission, in contrast with other quasar studies that suggest star formation dominates. To investigate, we use 70 RQQs from the Spitzer-Herschel Active Galaxy Survey. These quasars are all at z ˜ 1, thereby minimizing evolutionary effects, and have been selected to span a factor of ˜100 in optical luminosity, so that the luminosity dependence of their properties can be studied. We have imaged the sample using the Karl G. Jansky Very Large Array (JVLA), whose high sensitivity results in 35 RQQs being detected above 2σ. This radio data set is combined with far-infrared luminosities derived from grey-body fitting to Herschel photometry. By exploiting the far-infrared-radio correlation observed for star-forming galaxies, and comparing two independent estimates of the star-formation rate, we show that star formation alone is not sufficient to explain the total radio emission. Considering RQQs above a 2σ detection level in both the radio and the far-infrared, 92 per cent are accretion dominated, and the accretion process accounts for 80 per cent of the radio luminosity when summed across the objects. The radio emission connected with accretion appears to be correlated with the optical luminosity of the RQQ, whilst a weaker luminosity dependence is evident for the radio emission connected with star formation.

  9. RADIO REFRACTIVITY RADIO REFRACTIVITY STUDY IN AKURE ...

    African Journals Online (AJOL)

    eobe

    The basic parameters that describe the troposphere region are pressure, temperature and relative humidity. Variations in these conditions within the troposphere cause changes in the refractive index of air and large scale changes of refractive index with height cause radio waves to be refracted and the effect can be quite.

  10. On the Nature of Off-limb Flare Continuum Sources Detected by SDO/HMI

    Science.gov (United States)

    Heinzel, P.; Kleint, L.; Kašparová, J.; Krucker, S.

    2017-09-01

    The Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory has provided unique observations of off-limb flare emission. White-light continuum enhancements were detected in the “continuum” channel of the Fe 6173 Å line during the impulsive phase of the observed flares. In this paper we aim to determine which radiation mechanism is responsible for such enhancement being seen above the limb, at chromospheric heights around or below 1000 km. Using a simple analytical approach, we compare two candidate mechanisms, the hydrogen recombination continuum (Paschen) and the Thomson continuum due to scattering of disk radiation on flare electrons. Both mechanisms depend on the electron density, which is typically enhanced during the impulsive phase of a flare as the result of collisional ionization (both thermal and also non-thermal due to electron beams). We conclude that for electron densities higher than 1012 cm-3, the Paschen recombination continuum significantly dominates the Thomson scattering continuum and there is some contribution from the hydrogen free-free emission. This is further supported by detailed radiation-hydrodynamical (RHD) simulations of the flare chromosphere heated by the electron beams. We use the RHD code FLARIX to compute the temporal evolution of the flare-heating in a semi-circular loop. The synthesized continuum structure above the limb resembles the off-limb flare structures detected by HMI, namely their height above the limb, as well as the radiation intensity. These results are consistent with recent findings related to hydrogen Balmer continuum enhancements, which were clearly detected in disk flares by the IRIS near-ultraviolet spectrometer.

  11. Interferometry and synthesis in radio astronomy

    CERN Document Server

    Thompson, A Richard; Swenson Jr , George W

    2017-01-01

    This book is open access under a CC BY-NC 4.0 license. The third edition of this indispensable book in radio interferometry provides extensive updates to the second edition, including results and technical advances from the past decade; discussion of arrays that now span the full range of the radio part of the electromagnetic spectrum observable from the ground, 10 MHz to 1 THz; an analysis of factors that affect array speed; and an expanded discussion of digital signal-processing techniques and of scintillation phenomena and the effects of atmospheric water vapor on image distortion, among many other topics. With its comprehensiveness and detailed exposition of all aspects of the theory and practice of radio interferometry and synthesis imaging, this book has established itself as a standard reference in the field. It begins with an overview of the basic principles of radio astronomy, a short history of the development of radio interferometry, and an elementary discussion of the operation of an interferomete...

  12. Coarse-to-Fine Segmentation with Shape-Tailored Continuum Scale Spaces

    KAUST Repository

    Khan, Naeemullah

    2017-11-09

    We formulate an energy for segmentation that is designed to have preference for segmenting the coarse over fine structure of the image, without smoothing across boundaries of regions. The energy is formulated by integrating a continuum of scales from a scale space computed from the heat equation within regions. We show that the energy can be optimized without computing a continuum of scales, but instead from a single scale. This makes the method computationally efficient in comparison to energies using a discrete set of scales. We apply our method to texture and motion segmentation. Experiments on benchmark datasets show that a continuum of scales leads to better segmentation accuracy over discrete scales and other competing methods.

  13. Dusty but Mighty: Using Radio in the Critical Media Literacy Classroom

    Science.gov (United States)

    Todorova, Miglena S.

    2015-01-01

    In a culture dominated by images, what is the capacity of radio-making to enact the ideals and meet the objectives of critical medial literacy education that empowers learners and expands democracy? This article conceptualizes a radio-based critical media literacy approach drawing upon a course project called "Borderless Radio," where…

  14. Hubble Space Telescope NICMOS observations of the host galaxies of powerful radio sources : Does size matter?

    NARCIS (Netherlands)

    de Vries, WH; O'Dea, CP; Barthel, PD; Fanti, C; Fanti, R; Lehnert, MD

    2000-01-01

    We present near-infrared J- and K-band imaging of a sample of powerful radio source host galaxies with the Hubble Space Telescope NICMOS2 camera. These sources have been selected on their double-lobed radio structure and include a wide range of projected radio source sizes. The largest projected

  15. VCMM: a visual tool for continuum molecular modeling.

    Science.gov (United States)

    Bai, Shiyang; Lu, Benzhuo

    2014-05-01

    This paper describes the design and function of a visualization tool, VCMM, for visualizing and analyzing data, and interfacing solvers for generic continuum molecular modeling. In particular, an emphasis of the program is to treat the data set based on unstructured mesh as used in finite/boundary element simulations, which largely enhances the capabilities of current visualization tools in this area that only support structured mesh. VCMM is segmented into molecular, meshing and numerical modules. The capabilities of molecular module include molecular visualization and force field assignment. Meshing module contains mesh generation, analysis and visualization tools. Numerical module currently provides a few finite/boundary element solvers of continuum molecular modeling, and contains several common visualization tools for the numerical result such as line and plane interpolations, surface probing, volume rendering and stream rendering. Three modules can exchange data with each other and carry out a complete process of modeling. Interfaces are also designed in order to facilitate usage of other mesh generation tools and numerical solvers. We develop a technique to accelerate data retrieval and have combined many graphical techniques in visualization. VCMM is highly extensible, and users can obtain more powerful functions by introducing relevant plug-ins. VCMM can also be useful in other fields such as computational quantum chemistry, image processing, and material science. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Radio broadcasting via satellite

    Science.gov (United States)

    Helm, Neil R.; Pritchard, Wilbur L.

    1990-10-01

    Market areas offering potential for future narrowband broadcast satellites are examined, including international public diplomacy, government- and advertising-supported, and business-application usages. Technical issues such as frequency allocation, spacecraft types, transmission parameters, and radio receiver characteristics are outlined. Service and system requirements, advertising revenue, and business communications services are among the economic issues discussed. The institutional framework required to provide an operational radio broadcast service is studied, and new initiatives in direct broadcast audio radio systems, encompassing studies, tests, in-orbit demonstrations of, and proposals for national and international commercial broadcast services are considered.

  17. Unlocking radio broadcasts

    DEFF Research Database (Denmark)

    Lykke, Marianne; Skov, Mette

    2012-01-01

    This poster reports the preliminary results of a user study uncovering the information seeking behaviour of humanities scholars dedicated to radio research. The study is part of an interdisciplinary research project on radio culture and auditory resources. The purpose of the study is to inform...... the design of information architecture and interaction design of a research infrastructure that will enable future radio and audio based research. Results from a questionnaire survey on humanities scholars’ research interest and information needs, preferred access points, and indexing levels are reported...

  18. Shoestring Budget Radio Astronomy

    Science.gov (United States)

    Hoot, John E.

    2017-06-01

    The commercial exploitation of microwave frequencies for cellular, WiFi, Bluetooth, HDTV, and satellite digital media transmission has brought down the cost of the components required to build an effective radio telescope to the point where, for the cost of a good eyepiece, you can construct and operate a radio telescope. This paper sets forth a family of designs for 1421 MHz telescopes. It also proposes a method by which operators of such instruments can aggregate and archive data via the Internet. With 90 or so instruments it will be possible to survey the entire radio sky for transients with a 24 hour cadence.

  19. Evidence for Infrared-faint Radio Sources as z > 1 Radio-loud Active Galactic Nuclei

    Science.gov (United States)

    Huynh, Minh T.; Norris, Ray P.; Siana, Brian; Middelberg, Enno

    2010-02-01

    Infrared-Faint Radio Sources (IFRSs) are a class of radio objects found in the Australia Telescope Large Area Survey which have no observable mid-infrared counterpart in the Spitzer Wide-area Infrared Extragalactic (SWIRE) survey. The extended Chandra Deep Field South now has even deeper Spitzer imaging (3.6-70 μm) from a number of Legacy surveys. We report the detections of two IFRS sources in IRAC images. The non-detection of two other IFRSs allows us to constrain the source type. Detailed modeling of the spectral energy distribution of these objects shows that they are consistent with high-redshift (z >~ 1) active galactic nuclei.

  20. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... the head uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of ... the body being imaged, send and receive radio waves, producing signals that are detected by the coils. ...

  1. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... resonance imaging (MRI) uses a powerful magnetic field, radio waves and a computer to produce detailed pictures ... medical conditions. MRI uses a powerful magnetic field, radio frequency pulses and a computer to produce detailed ...

  2. Direction-dependent Corrections in Polarimetric Radio Imaging. II. A-solver Methodology: A Low-order Solver for the A-term of the A-projection Algorithm

    Science.gov (United States)

    Jagannathan, P.; Bhatnagar, S.; Brisken, W.; Taylor, A. R.

    2018-01-01

    The effects of the antenna far-field power pattern limits the imaging performance of modern wide-bandwidth, high-sensitivity interferometric radio telescopes. Given a model for the aperture illumination pattern (AIP) of the antenna, referred to as the A-term, the wide-band (WB) A-Projection algorithm corrects for the effects of its time, frequency, and polarization structure. The level to which this correction is possible depends on how accurately the A-term represents the true AIP. In this paper, we describe the A-Solver methodology that combines physical modeling with optimization to holographic measurements to build an accurate model for the AIP. Using a parametrized ray-tracing code as the predictor, we solve for the frequency dependence of the antenna optics and show that the resulting low-order model for the Karl G. Jansky Very Large Array antenna captures the dominant frequency-dependent terms. The A-Solver methodology described here is generic and can be adapted for other types of antennas as well. The parameterization is based on the physical characteristics of the antenna structure and optics and is therefore arguably a compact representation (minimized degrees of freedom) of the frequency-dependent structure of the antenna A-term. In this paper, we also show that the parameters derived from A-Solver methodology are expected to improve sensitivity and imaging performance out to the first side-lobe of the antenna.

  3. AN APPARENT REDSHIFT DEPENDENCE OF QUASAR CONTINUUM: IMPLICATION FOR COSMIC DUST EXTINCTION?

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Xiaoyi; Shen, Shiyin; Shao, Zhengyi; Yin, Jun, E-mail: ssy@shao.ac.cn [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)

    2015-04-01

    We investigate the luminosity and redshift dependence of the quasar continuum by means of the composite spectrum using a large non-BAL radio-quiet quasar sample drawn from the Sloan Digital Sky Survey. Quasar continuum slopes in the UV-Opt band are measured at two different wavelength ranges, i.e., α{sub ν12} (1000 ∼ 2000 Å) and α{sub ν24} (2000 ∼ 4000 Å) derived from a power-law fitting. Generally, the UV spectra slope becomes harder (higher α{sub ν}) toward higher bolometric luminosity. On the other hand, when quasars are further grouped into luminosity bins, we find that both α{sub ν12} and α{sub ν24} show significant anti-correlations with redshift (i.e., the quasar continuum becomes redder toward higher redshift). We suggest that the cosmic dust extinction is very likely the cause of this observed α{sub ν} − z relation. We build a simple cosmic dust extinction model to quantify the observed reddening tendency and find an effective dust density nσ{sub v} ∼ 10{sup −5}h Mpc{sup −1} at z < 1.5. The other possibilities that could produce such a reddening effect have also been discussed.

  4. The geometrical language of continuum mechanics

    CERN Document Server

    Epstein, Marcelo

    2010-01-01

    This book presents the fundamental concepts of modern differential geometry within the framework of continuum mechanics. It is divided into three parts of roughly equal length. The book opens with a motivational chapter to impress upon the reader that differential geometry is indeed the natural language of continuum mechanics or, better still, that the latter is a prime example of the application and materialization of the former. In the second part, the fundamental notions of differential geometry are presented with rigor using a writing style that is as informal as possible. Differentiable manifolds, tangent bundles, exterior derivatives, Lie derivatives, and Lie groups are illustrated in terms of their mechanical interpretations. The third part includes the theory of fiber bundles, G-structures, and groupoids, which are applicable to bodies with internal structure and to the description of material inhomogeneity. The abstract notions of differential geometry are thus illuminated by practical and intuitivel...

  5. Mesoscopic and continuum modelling of angiogenesis

    KAUST Repository

    Spill, F.

    2014-03-11

    Angiogenesis is the formation of new blood vessels from pre-existing ones in response to chemical signals secreted by, for example, a wound or a tumour. In this paper, we propose a mesoscopic lattice-based model of angiogenesis, in which processes that include proliferation and cell movement are considered as stochastic events. By studying the dependence of the model on the lattice spacing and the number of cells involved, we are able to derive the deterministic continuum limit of our equations and compare it to similar existing models of angiogenesis. We further identify conditions under which the use of continuum models is justified, and others for which stochastic or discrete effects dominate. We also compare different stochastic models for the movement of endothelial tip cells which have the same macroscopic, deterministic behaviour, but lead to markedly different behaviour in terms of production of new vessel cells. © 2014 Springer-Verlag Berlin Heidelberg.

  6. Nonlinear continuum mechanics and large inelastic deformations

    CERN Document Server

    Dimitrienko, Yuriy I

    2010-01-01

    This book provides a rigorous axiomatic approach to continuum mechanics under large deformation. In addition to the classical nonlinear continuum mechanics - kinematics, fundamental laws, the theory of functions having jump discontinuities across singular surfaces, etc. - the book presents the theory of co-rotational derivatives, dynamic deformation compatibility equations, and the principles of material indifference and symmetry, all in systematized form. The focus of the book is a new approach to the formulation of the constitutive equations for elastic and inelastic continua under large deformation. This new approach is based on using energetic and quasi-energetic couples of stress and deformation tensors. This approach leads to a unified treatment of large, anisotropic elastic, viscoelastic, and plastic deformations. The author analyses classical problems, including some involving nonlinear wave propagation, using different models for continua under large deformation, and shows how different models lead t...

  7. Music, radio and mediatization

    DEFF Research Database (Denmark)

    Michelsen, Morten; Krogh, Mads

    2016-01-01

    Mediatization has become a key concept for understanding the relations between media and other cultural and social fields. Contributing to the discussions related to the concept of mediatization, this article discusses how practices of radio and music(al life) influence each other. We follow Deacon......’s and Stanyer’s advice to supplement the concept of mediatization with ‘a series of additional concepts at lower levels of abstraction’ and suggest, in this respect, the notion of heterogeneous milieus of music–radio. Hereby, we turn away from the all-encompassing perspectives related to the concept...... of mediatization where media as such seem to be ascribed agency. Instead, we consider historical accounts of music–radio in order to address the complex nonlinearity of concrete processes of mediatization as they take place in the multiple meetings between a decentred notion of radio and musical life....

  8. The digital sport radio.

    Directory of Open Access Journals (Sweden)

    Hilario José ROMERO BEJARANO

    2014-07-01

    Full Text Available Radio has been immersed in recent years in a phase of technological integration and business of multimedia, as well as diversification of systems and channels for broadcasting. In addition, Internet has been consolidated as the platform of digital radio that more has evolved as a result of its continued expansion. However, the merger radio-Internet must be understood as a new form of communication, and not solely as a new complementary medium. In this context, it is of great interest to analyze that transformations in the way of reception, contents, languages, programs and schedules, has brought with it for the radio that integration. To this end is taken as main reference the sports areas, a key aspect and broadly representative of the current broadcasting landscape.

  9. Social cognitive radio networks

    CERN Document Server

    Chen, Xu

    2015-01-01

    This brief presents research results on social cognitive radio networks, a transformational and innovative networking paradigm that promotes the nexus between social interactions and cognitive radio networks. Along with a review of the research literature, the text examines the key motivation and challenges of social cognitive radio network design. Three socially inspired distributed spectrum sharing mechanisms are introduced: adaptive channel recommendation mechanism, imitation-based social spectrum sharing mechanism, and evolutionarily stable spectrum access mechanism. The brief concludes with a discussion of future research directions which ascertains that exploiting social interactions for distributed spectrum sharing will advance the state-of-the-art of cognitive radio network design, spur a new line of thinking for future wireless networks, and enable novel wireless service and applications.

  10. Eratosthenes via Ham Radio

    Science.gov (United States)

    Koser, John F.

    1975-01-01

    A secondary geology class used Eratosthenes' method for measuring the circumference of the earth by comparing their measurements of the shadow of a vertical rod to the measurements made by another person contacted by ham radio. (MLH)

  11. Everyday Radio Telescope

    CERN Document Server

    Mandal, Pranshu; Kumar, Pratik; Yelikar, Anjali; Soni, Kanchan; T, Vineeth Krishna

    2016-01-01

    We have developed an affordable, portable college level radio telescope for amateur radio astronomy which can be used to provide hands-on experience with the fundamentals of a radio telescope and an insight into the realm of radio astronomy. With our set-up one can measure brightness temperature and flux of the Sun at 11.2 GHz and calculate the beam width of the antenna. The set-up uses commercially available satellite television receiving system and parabolic dish antenna. We report the detection of point sources like Saturn and extended sources like the galactic arm of the Milky way. We have also developed python pipeline, which are available for free download, for data acquisition and visualization.

  12. Continuum RPA calculation of escape widths

    Energy Technology Data Exchange (ETDEWEB)

    Vertse, T. (Inst. of Nuclear Research, Hungarian Academy of Sciences, Debrecen (Hungary)); Curutchet, P.; Liotta, R.J. (Manne Siegbahn Inst. of Physics, Stockholm (Sweden)); Bang, J. (Niels Bohr Inst., Copenhagen (Denmark)); Giai, N. van (Inst. de Physique Nucleaire, 91 - Orsay (France))

    1991-07-25

    Particle-hole partial decay widths are calculated within the continuum RPA exactly, i.e. without any further approximation, in a square well plus Coulomb potential and using a separable residual interaction. The results are compared with the ones obtained by making pole expansions of the single-particle Green functions (Berggren and Mittag-Leffler). It is found that the Berggren and Mittag-Leffler expansions give results in good agreement with the 'exact' ones. (orig.).

  13. On continuum driven winds from rotating stars

    OpenAIRE

    Shacham, Tomer; Shaviv, Nir J.

    2012-01-01

    We study the dynamics of continuum driven winds from rotating stars, and develop an approximate analytical model. We then discuss the evolution of stellar angular momentum, and show that just above the Eddington limit, the winds are sufficiently concentrated towards the poles to spin up the star. A twin-lobe structure of the ejected nebula is seen to be a generic consequence of critical rotation. We find that if the pressure in such stars is sufficiently dominated by radiation, an equatorial ...

  14. Quantum heat engine with continuum working medium

    OpenAIRE

    Li, S.; Wang, H.; Sun, Y. D.; Yi, X. X.

    2006-01-01

    We introduce a new quantum heat engine, in which the working medium is a quantum system with a discrete level and a continuum. Net work done by this engine is calculated and discussed. The results show that this quantum heat engine behaves like the two-level quantum heat engine in both the high-temperature and the low-temperature limits, but it operates differently in temperatures between them. The efficiency of this quantum heat engine is also presented and discussed.

  15. Sensitivity filtering from a continuum mechanics perspective

    DEFF Research Database (Denmark)

    Sigmund, Ole; Maute, Kurt

    2012-01-01

    In topology optimization filtering is a popular approach for preventing numerical instabilities. This short note shows that the well-known sensitivity filtering technique, that prevents checkerboards and ensures mesh-independent designs in density-based topology optimization, is equivalent to min...... to minimizing compliance for nonlocal elasticity problems known from continuum mechanics. Hence, the note resolves the long-standing quest for finding an explanation and physical motivation for the sensitivity filter....

  16. Continuum mechanics the birthplace of mathematical models

    CERN Document Server

    Allen, Myron B

    2015-01-01

    Continuum mechanics is a standard course in many graduate programs in engineering and applied mathematics as it provides the foundations for the various differential equations and mathematical models that are encountered in fluid mechanics, solid mechanics, and heat transfer.  This book successfully makes the topic more accessible to advanced undergraduate mathematics majors by aligning the mathematical notation and language with related courses in multivariable calculus, linear algebra, and differential equations; making connections with other areas of applied mathematics where parial differe

  17. On the Continuum of Eating Disorders

    OpenAIRE

    Hawkins, Lana Lee Munro

    2007-01-01

    Theorists and researchers have long debated as to whether the differences between subthreshold levels of eating disturbances and diagnosable eating disorders are a difference of degree (the continuum hypothesis) or a difference of kind (the discontinuity hypothesis). The present study investigated the relationship between level of eating disordered behaviour and the psychopathology associated with, and thought by some to be prodromal factors in, the development of clinically diagnosable eatin...

  18. Wireless radio a history

    CERN Document Server

    Coe, Lewis

    2006-01-01

    ""Informative...recommended""--Choice; ""interesting...a good read...well worth reading""--Contact Magazine. This history first looks at Marconi's wireless communications system and then explores its many applications, including marine radio, cellular telephones, police and military uses, television and radar. Radio collecting is also discussed, and brief biographies are provided for the major figures in the development and use of the wireless.

  19. The thermal infrared continuum in solar flares

    Science.gov (United States)

    Fletcher, Lyndsay; Simoes, Paulo; Kerr, Graham Stewart; Hudson, Hugh S.; Gimenez de Castro, C. Guillermo; Penn, Matthew J.

    2017-08-01

    Observations of the Sun with the Atacama Large Millimeter Array have now started, and the thermal infrared will regularly be accessible from the NSF’s Daniel K. Inouye Solar Telescope. Motivated by the prospect of these new observations, and by recent flare detections in the mid infrared, we set out here to model and understand the source of the infrared continuum in flares, and to explore its diagnostic capability for the physical conditions in the flare atmosphere. We use the 1D radiation hydrodynamics code RADYN to calculate mid-infrared continuum emission from model atmospheres undergoing sudden deposition of energy by non-thermal electrons. We identify and characterise the main continuum thermal emission processes relevant to flare intensity enhancement in the mid- to far-infrared (2-200 micron) spectral range as free-free emission on neutrals and ions. We find that the infrared intensity evolution tracks the energy input to within a second, albeit with a lingering intensity enhancement, and provides a very direct indication of the evolution of the atmospheric ionization. The prediction of highly impulsive emission means that, on these timescales, the atmospheric hydrodynamics need not be considered in analysing the mid-IR signatures.

  20. Lattice Boltzmann algorithm for continuum multicomponent flow

    Science.gov (United States)

    Halliday, I.; Hollis, A. P.; Care, C. M.

    2007-08-01

    We present a multicomponent lattice Boltzmann simulation for continuum fluid mechanics, paying particular attention to the component segregation part of the underlying algorithm. In the principal result of this paper, the dynamics of a component index, or phase field, is obtained for a segregation method after U. D’Ortona [Phys. Rev. E 51, 3718 (1995)], due to Latva-Kokko and Rothman [Phys. Rev. E 71 056702 (2005)]. The said dynamics accord with a simulation designed to address multicomponent flow in the continuum approximation and underwrite improved simulation performance in two main ways: (i) by reducing the interfacial microcurrent activity considerably and (ii) by facilitating simulational access to regimes of flow with a low capillary number and drop Reynolds number [I. Halliday, R. Law, C. M. Care, and A. Hollis, Phys. Rev. E 73, 056708 (2006)]. The component segregation method studied, used in conjunction with Lishchuk’s method [S. V. Lishchuk, C. M. Care, and I. Halliday, Phys. Rev. E 67, 036701 (2003)], produces an interface, which is distributed in terms of its component index; however, the hydrodynamic boundary conditions which emerge are shown to support the notion of a sharp, unstructured, continuum interface.

  1. Classics in radio astronomy

    CERN Document Server

    Sullivan, Woodruff Turner

    1982-01-01

    Radio techniques were the nrst to lead astronomy away from the quiescent and limited Universe revealed by traditional observations at optical wave­ lengths. In the earliest days of radio astronomy, a handful of radio physicists and engineers made one startling discovery after another as they opened up the radio sky. With this collection of classic papers and the extensive intro­ ductory material, the reader can experience these exciting discoveries, as well as understand the developing techniques and follow the motivations which prompted the various lines of inquiry. For instance he or she will follow in detail the several attempts to detect radio waves from the sun at the turn of the century; the unravelling by Jansky of a "steady hiss type static"; the incredible story of Reber who built a 9 meter dish in his backyard in 1937 and then mapped the Milky Way; the vital discoveries by Hey and colleagues of radio bursts from the Sun and of a discrete source in the constellation of Cygnus; the development of re...

  2. Coupling discrete and continuum concentration particle models for multiscale and hybrid molecular-continuum simulations

    Science.gov (United States)

    Petsev, Nikolai D.; Leal, L. Gary; Shell, M. Scott

    2017-12-01

    Hybrid molecular-continuum simulation techniques afford a number of advantages for problems in the rapidly burgeoning area of nanoscale engineering and technology, though they are typically quite complex to implement and limited to single-component fluid systems. We describe an approach for modeling multicomponent hydrodynamic problems spanning multiple length scales when using particle-based descriptions for both the finely resolved (e.g., molecular dynamics) and coarse-grained (e.g., continuum) subregions within an overall simulation domain. This technique is based on the multiscale methodology previously developed for mesoscale binary fluids [N. D. Petsev, L. G. Leal, and M. S. Shell, J. Chem. Phys. 144, 084115 (2016)], simulated using a particle-based continuum method known as smoothed dissipative particle dynamics. An important application of this approach is the ability to perform coupled molecular dynamics (MD) and continuum modeling of molecularly miscible binary mixtures. In order to validate this technique, we investigate multicomponent hybrid MD-continuum simulations at equilibrium, as well as non-equilibrium cases featuring concentration gradients.

  3. A tumor-specific cleavable nanosystem of PEG-modified C60@Au hybrid aggregates for radio frequency-controlled release, hyperthermia, photodynamic therapy and X-ray imaging.

    Science.gov (United States)

    Shi, Jinjin; Chen, Zhaoyang; Wang, Lei; Wang, Binghua; Xu, Lihua; Hou, Lin; Zhang, Zhenzhong

    2016-01-01

    Taking advantages of fullerene (C60) and gold nanoparticles (AuNPs) for potentials in photodynamic therapy (PDT), drug delivery and radio frequency thermal therapy (RTT), a C60@Au hybrid nanocomposite was synthesized by chemical deposition of Au nanoparticles onto C60, and functionalized by PEG5000 via a pH cleavable hydrazone bond, making C60@Au-PEG keep the PEG on the surface of drug delivery system during circulation but dissociate PEG from the system after accumulation in tumor tissue, then doxorubicin (DOX) was loaded onto C60@Au-PEG with a very high drug loading efficiency. The release profiles of DOX from C60@Au-PEG/DOX showed strong dependences on radio frequency (RF). For the drug delivery, C60@Au-PEG/DOX afforded much higher antitumor efficacy owing to 8.6-fold higher DOX uptake of tumor than DOX. Besides, in this work, C60@Au-PEG/DOX not only served as a powerful RTT agent for RF-thermal ablation of tumor and a strong photosensitizer (PS) for PDT, but also as an X-ray contrast agent for tumor diagnosis. In the in vitro and in vivo studies, C60@Au-PEG/DOX showed excellent chemo-RF thermal-photodynamic therapeutic efficacy, RF-controlled drug releasing function, tumor targeting property, tumoral acid PEG dissociating character and X-ray imaging ability, demonstrating that there is a great potential of C60@Au-PEG/DOX for simultaneous diagnosis and therapy in cancer treatment. A significant challenge in cancer therapy is to maximize the therapeutic efficacy and minimize the side effects. In the past decade, a lot of nanoparticles have been used as the carriers for efficient drug delivery. However, the design of drug delivery system (DDS) with stimuli-responsive controlled-release property, simultaneous diagnosis and therapy functions is still a challenge. Herein, we developed a new drug delivery system (C60@Au-PEG/DOX), and explored its applications in tumor therapy. The in vitro and in vivo results showed C60@Au-PEG/DOX could significantly improve the

  4. Images

    Data.gov (United States)

    National Aeronautics and Space Administration — Images for the website main pages and all configurations. The upload and access points for the other images are: Website Template RSW images BSCW Images HIRENASD...

  5. Advanced inside-out tracking approach for real-time combination of MRI and US images in the radio-frequency shielded room using combination markers.

    Science.gov (United States)

    Nagaraj, Yeshaswini; Benedicks, Christian; Matthies, Philipp; Friebe, Michael

    2016-08-01

    For the real-time fusion of different modalities, a variety of tracking methods are available including the optical, electromagnetic (EM) and image-based tracking. But as a drawback optical tracking suffers from line of sight issues and EM tracking requires the manual referencing for the fusion procedure and is not usable in Magnetic Resonance Imaging (MRI) environment. To avoid these issues, we propose a real-time setup containing a camera capable of inside-Out tracking using combined circular markers attached to Ultrasound (US) probe and a suitable platform for automatic overlay of MRI and US image using markers. This new approach could help clinicians carry out successful surgical procedures by requiring least system interaction and solving line of sight issues. As a proof-of-concept, we show our first result by mimicking common liver tumor intervention using framed marker fusion technique in a candle gel phantom. We evaluated the tracking error distances using the combination of special markers with Inside-Out approach and conventional optical tracking. The results achieved show comparable performance to the standard Outside-In tracking and manual reference approach, while easing the interventional procedure in terms of hardware and line of sight requirements.

  6. Continuum and HI surveys working together

    NARCIS (Netherlands)

    Oosterloo, T.; Maddox, N.

    2015-01-01

    SKA1 will offer an enormous improvement in observational capabilities for radio astronomy. The astronomical community is very eager to exploit these new possibilities, so much so that the ambitions for using SKA1 far exceed what is possible given the available observing time. An obvious strategy to

  7. The Spiral Host Galaxy of the Double Radio Source 0313-192

    Science.gov (United States)

    Keel, William C.; White, Raymond E., III; Owen, Frazer N.; Ledlow, Michael J.

    2006-12-01

    We present new Hubble Space Telescope (HST), Gemini South, and Chandra observations of the radio galaxy 0313-192, which hosts a 350 kpc double source and jets, even though previous data have suggested that it is a spiral galaxy. We measure the bulge scale and the luminosity, radial, and vertical profiles of disk starlight and consider the distributions of H II regions and absorbing dust. In each case the HST data confirm its classification as an edge-on spiral galaxy, the only such system known to produce such an extended radio source of this kind. The Gemini near-IR images and Chandra spectral fit reveal a strongly obscured central active galactic nucleus (AGN), seen through the entire interstellar medium path length of the disk and showing X-ray evidence of additional absorption from warm or dense material close to the central object. We consider several possible mechanisms for producing such a rare combination of AGN and host properties, some combination of which may be at work. These include an unusually luminous bulge (suggesting a black hole of mass ~8×108 Msolar), the orientation of the jets near the pole of the gas-rich disk, and some evidence of a weak gravitational interaction that has warped the disk and could have enhanced fueling of the central engine. We detect an X-ray counterpart of the kiloparsec-scale radio jet emerging to the south; jet/counterjet limits on both radio and X-ray regimes allow them to be symmetric if seen more than 15° from the plane of the sky, still consistent with the jet axes being within ~30° of the poles of the gas-rich galaxy disk. A linear or disklike emission-line structure is seen around the nucleus, inclined by ~20° to the stellar disk but nearly perpendicular to the jets; this may represent the aftermath of a galaxy encounter, in which gas is photoionized by a direct view of the nuclear continuum. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute

  8. Tools of radio astronomy

    CERN Document Server

    Wilson, Thomas L; Hüttemeister, Susanne

    2013-01-01

    This 6th edition of “Tools of Radio Astronomy”, the most used introductory text in radio astronomy, has been revised to reflect the current state of this important branch of astronomy. This includes the use of satellites, low radio frequencies, the millimeter/sub-mm universe, the Cosmic Microwave Background and the increased importance of mm/sub-mm dust emission. Several derivations and presentations of technical aspects of radio astronomy and receivers, such as receiver noise, the Hertz dipole and  beam forming have been updated, expanded, re-worked or complemented by alternative derivations. These reflect advances in technology. The wider bandwidths of the Jansky-VLA and long wave arrays such as LOFAR and mm/sub-mm arrays such as ALMA required an expansion of the discussion of interferometers and aperture synthesis. Developments in data reduction algorithms have been included. As a result of the large amount of data collected in the past 20 years, the discussion of solar system radio astronomy, dust em...

  9. Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies

    Science.gov (United States)

    Kapińska, A. D.; Terentev, I.; Wong, O. I.; Shabala, S. S.; Andernach, H.; Rudnick, L.; Storer, L.; Banfield, J. K.; Willett, K. W.; de Gasperin, F.; Lintott, C. J.; López-Sánchez, Á. R.; Middelberg, E.; Norris, R. P.; Schawinski, K.; Seymour, N.; Simmons, B.

    2017-12-01

    Hybrid morphology radio sources (HyMoRS) are a rare type of radio galaxy that display different Fanaroff-Riley classes on opposite sides of their nuclei. To enhance the statistical analysis of HyMoRS, we embarked on a large-scale search of these sources within the international citizen science project, Radio Galaxy Zoo (RGZ). Here, we present 25 new candidate hybrid morphology radio galaxies. Our selected candidates are moderate power radio galaxies ({L}{median}=4.7× {10}24 W Hz-1 sr-1) at redshifts 0.14 1 Mpc) radio galaxies, one resides at the center of a galaxy cluster, and one is hosted by a rare green bean galaxy. Although the origin of the hybrid morphology radio galaxies is still unclear, this type of radio source starts depicting itself as a rather diverse class. We discuss hybrid radio morphology formation in terms of the radio source environment (nurture) and intrinsically occurring phenomena (nature; activity cessation and amplification), showing that these peculiar radio galaxies can be formed by both mechanisms. While high angular resolution follow-up observations are still necessary to confirm our candidates, we demonstrate the efficacy of the RGZ in the pre-selection of these sources from all-sky radio surveys, and report the reliability of citizen scientists in identifying and classifying complex radio sources.

  10. IHW COMET HALLEY RADIO CONTINUUM ARRAY DATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA's International Halley Watch (IHW) has created a Comet Halley Archive. The collection of data spans the full wavelength range as submitted by scientists to the...

  11. INTERSTELLAR SCINTILLATION AND THE RADIO COUNTERPART OF THE FAST RADIO BURST FRB 150418

    Energy Technology Data Exchange (ETDEWEB)

    Akiyama, Kazunori [Massachusetts Institute of Technology, Haystack Observatory, Route 40, Westford, MA 01886 (United States); Johnson, Michael D., E-mail: kazu@haystack.mit.edu [Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2016-06-10

    Keane et al. have recently reported the discovery of a new fast radio burst (FRB), FRB 150418, with a promising radio counterpart at 5.5 and 7.5 GHz—a rapidly decaying source, falling from 200–300 μ Jy to 100 μ Jy on timescales of ∼6 days. This transient source may be associated with an elliptical galaxy at redshift z = 0.492, providing the first firm spectroscopic redshift for an FRB and the ability to estimate the density of baryons in the intergalactic medium via the combination of known redshift and radio dispersion of the FRB. An alternative explanation, first suggested by Williams and Berger, is that the identified counterpart may instead be a compact active galactic nucleus (AGN). The putative counterpart’s variation may then instead be extrinsic, caused by refractive scintillation in the ionized interstellar medium of the Milky Way, which would invalidate the association with FRB 150418. We examine this latter explanation in detail and show that the reported observations are consistent with scintillating radio emission from the core of a radio-loud AGN having a brightness temperature T {sub b} ≳ 10{sup 9} K. Using numerical simulations of the expected scattering for the line of sight to FRB 150418, we provide example images and light curves of such an AGN at 5.5 and 7.5 GHz. These results can be compared with continued radio monitoring to conclusively determine the importance of scintillation for the observed radio variability, and they show that scintillation is a critical consideration for continued searches for FRB counterparts at radio wavelengths.

  12. Non-classical continuum mechanics a dictionary

    CERN Document Server

    Maugin, Gérard A

    2017-01-01

    This dictionary offers clear and reliable explanations of over 100 keywords covering the entire field of non-classical continuum mechanics and generalized mechanics, including the theory of elasticity, heat conduction, thermodynamic and electromagnetic continua, as well as applied mathematics. Every entry includes the historical background and the underlying theory, basic equations and typical applications. The reference list for each entry provides a link to the original articles and the most important in-depth theoretical works. Last but not least, every entry is followed by a cross-reference to other related subject entries in the dictionary.

  13. Set theory and the continuum hypothesis

    CERN Document Server

    Cohen, Paul J

    2008-01-01

    This exploration of a notorious mathematical problem is the work of the man who discovered the solution. The independence of the continuum hypothesis is the focus of this study by Paul J. Cohen. It presents not only an accessible technical explanation of the author's landmark proof but also a fine introduction to mathematical logic. An emeritus professor of mathematics at Stanford University, Dr. Cohen won two of the most prestigious awards in mathematics: in 1964, he was awarded the American Mathematical Society's Bôcher Prize for analysis; and in 1966, he received the Fields Medal for Logic.

  14. Continuum modeling an approach through practical examples

    CERN Document Server

    Muntean, Adrian

    2015-01-01

    This book develops continuum modeling skills and approaches the topic from three sides: (1) derivation of global integral laws together with the associated local differential equations, (2) design of constitutive laws and (3) modeling boundary processes. The focus of this presentation lies on many practical examples covering aspects such as coupled flow, diffusion and reaction in porous media or microwave heating of a pizza, as well as traffic issues in bacterial colonies and energy harvesting from geothermal wells. The target audience comprises primarily graduate students in pure and applied mathematics as well as working practitioners in engineering who are faced by nonstandard rheological topics like those typically arising in the food industry.

  15. Histidine in Continuum Electrostatics Protonation State Calculations

    Science.gov (United States)

    Couch, Vernon; Stuchebruckhov, Alexei

    2014-01-01

    A modification to the standard continuum electrostatics approach to calculate protein pKas which allows for the decoupling of histidine tautomers within a two state model is presented. Histidine with four intrinsically coupled protonation states cannot be easily incorporated into a two state formalism because the interaction between the two protonatable sites of the imidazole ring is not purely electrostatic. The presented treatment, based on a single approximation of the interrelation between histidine’s charge states, allows for a natural separation of the two protonatable sites associated with the imidazole ring as well as the inclusion of all protonation states within the calculation. PMID:22072521

  16. Lyman Continuum Leakage in the Local Universe

    Science.gov (United States)

    Leitherer, Claus; Hernandez, Svea; Lee, Janice; Oey, Sally

    2015-08-01

    Star-forming galaxies are viable candidates for providing the ionizing photon supply accounting for the reionization of the early universe. However, direct determination of the fraction of ionizing photons that can escape the optically thick galaxy ISM is challenging. I will discuss Lyman continuum observations of a sample of massive young star clusters in local galaxies which take advantage of a new capability of HST's Cosmic Origins Spectrograph. The derived photon leakages are compared to values found at high redshift and discussed in the context of cosmological models.

  17. Continuum description of avalanches in granular media.

    Energy Technology Data Exchange (ETDEWEB)

    Aranson, I. S.; Tsimring, L. S.

    2000-12-05

    A continuum theory of partially fluidized granular flows is proposed. The theory is based on a combination of the mass and momentum conservation equations with the order parameter equation which describes the transition between flowing and static components of the granular system. We apply this model to the dynamics of avalanches in chutes. The theory provides a quantitative description of recent observations of granular flows on rough inclined planes (Daerr and Douady 1999): layer bistability, and the transition from triangular avalanches propagating downhill at small inclination angles to balloon-shaped avalanches also propagating uphill for larger angles.

  18. Optical detection of radio waves through a nanomechanical transducer

    DEFF Research Database (Denmark)

    Bagci, T.; Simonsen, A.; Schmid, Silvan

    2014-01-01

    . The corresponding half-wave voltage is in the microvolt range, orders of magnitude less than that of standard optical modulators. The noise of the transducer--beyond the measured 800 pV Hz-1/2 Johnson noise of the resonant circuit--consists of the quantum noise of light and thermal fluctuations of the membrane......Low-loss transmission and sensitive recovery of weak radio-frequency and microwave signals is a ubiquitous challenge, crucial in radio astronomy, medical imaging, navigation, and classical and quantum communication. Efficient up-conversion of radio-frequency signals to an optical carrier would...... strong coupling between the voltage fluctuations in a radio-frequency resonance circuit and the membrane's displacement, which is simultaneously coupled to light reflected off its surface. The radio-frequency signals are detected as an optical phase shift with quantum-limited sensitivity...

  19. Galactic radio astronomy

    CERN Document Server

    Sofue, Yoshiaki

    2017-01-01

    This book is a concise primer on galactic radio astronomy for undergraduate and graduate students, and provides wide coverage of galactic astronomy and astrophysics such as the physics of interstellar matter and the dynamics and structure of the Milky Way Galaxy and galaxies. Radio astronomy and its technological development have led to significant progress in galactic astronomy and contributed to understanding interstellar matter and galactic structures. The book begins with the fundamental physics of radio-wave radiation, i.e., black body radiation, thermal emission, synchrotron radiation, and HI and molecular line emissions. The author then gives overviews of ingredients of galactic physics, including interstellar matter such as the neutral (HI), molecular hydrogen, and ionized gases, as well as magnetic fields in galaxies. In addition, more advanced topics relevant to the Galaxy and galaxies are also contained here: star formation, supernova remnants, the Galactic Center and black holes, galactic dynamics...

  20. Radio frequency spectrum management

    Science.gov (United States)

    Sujdak, E. J., Jr.

    1980-03-01

    This thesis is a study of radio frequency spectrum management as practiced by agencies and departments of the Federal Government. After a brief introduction to the international agency involved in radio frequency spectrum management, the author concentrates on Federal agencies engaged in frequency management. These agencies include the National Telecommunications and Information Administration (NTIA), the Interdepartment Radio Advisory Committee (IRAC), and the Department of Defense (DoD). Based on an analysis of Department of Defense frequency assignment procedures, recommendations are given concerning decentralizing military frequency assignment by delegating broader authority to unified commanders. This proposal includes a recommendation to colocate the individual Service frequency management offices at the Washington level. This would result in reduced travel costs, lower manpower requirements, and a common tri-Service frequency management data base.

  1. Radio and infrared study of the star-forming region IRAS 20286+4105

    Science.gov (United States)

    Ramachandran, Varsha; Das, S. R.; Tej, A.; Vig, S.; Ghosh, S. K.; Ojha, D. K.

    2017-03-01

    In this paper, we present a multiwavelength investigation of the star-forming complex IRAS 20286+4105, located in the Cygnus X region. Near-infrared K-band data are used to revisit the cluster/stellar group identified in previous studies. Radio continuum observations at 610 and 1280 MHz show the presence of a H II region possibly powered by a star of spectral type B0-B0.5. The cometary morphology of the ionized region is explained by invoking the bow-shock model, where the likely association with a nearby supernova remnant is also explored. A compact radio knot with a non-thermal spectral index is detected towards the centre of the cloud. Mid-infrared data from the Spitzer Legacy Survey of the Cygnus X region show the presence of six Class I young stellar objects inside the cloud. Thermal dust emission in this complex is modelled using Herschel far-infrared data to generate dust temperature and column density maps. Herschel images also show the presence of two clumps in this region, the masses of which are estimated to be ∼175 and 30 M⊙. The mass-radius relation and the surface density of the clumps mean that they do not qualify as massive star-forming sites. An overall picture of a runaway star ionizing the cloud and a triggered population of intermediate-mass, Class I sources located towards the cloud centre emerges from this multiwavelength study. Variation in the dust emissivity spectral index is shown to exist in this region and is seen to have an inverse relation with the dust temperature.

  2. JVLA observations of IC 348 SW: Compact radio sources and their nature

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez, Luis F.; Zapata, Luis A.; Palau, Aina, E-mail: l.rodriguez@crya.unam.mx, E-mail: l.zapata@crya.unam.mx, E-mail: a.palau@crya.unam.mx [Centro de Radioastronomía y Astrofísica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacán (Mexico)

    2014-07-20

    We present sensitive 2.1 and 3.3 cm Jansky Very Large Array radio continuum observations of the region IC 348 SW. We detect a total of 10 compact radio sources in the region, 7 of which are first reported here. One of the sources is associated with the remarkable periodic time-variable infrared source LRLL 54361, opening the possibility of monitoring this object at radio wavelengths. Four of the sources appear to be powering outflows in the region, including HH 211 and HH 797. In the case of the rotating outflow HH 797, we detect a double radio source at its center, separated by ∼3''. Two of the sources are associated with infrared stars that possibly have gyrosynchrotron emission produced in active magnetospheres. Finally, three of the sources are interpreted as background objects.

  3. SNR radio spectral index distribution and its correlation with polarization. a case study: the Lupus Loop

    Science.gov (United States)

    Borka Jovanović, V.; Jovanović, P.; Borka, D.

    2017-04-01

    We use radio-continuum all-sky surveys at 1420 and 408 MHz with the aim to investigate properties of the Galactic radio source Lupus Loop. The survey data at 1435 MHz, with the linear polarization of the southern sky, are also used. We calculate properties of this supernova remnant: the brightness temperature, surface brightness and radio spectral index. To determine its borders and to calculate its properties, we use the method we have developed. The non-thermal nature of its radiation is confirmed. The distribution of spectral index over its area is also given. A significant correlation between the radio spectral index distribution and the corresponding polarized intensity distribution inside the loop borders is found, indicating that the polarization maps could provide us information about the distribution of the interstellar medium, and thus could represent one additional way to search for new Galactic loops.

  4. A reconfigurable radio architecture for Cognitive Radio in emergency networks

    NARCIS (Netherlands)

    Zhang, Q.; Kokkeler, Andre B.J.; Smit, Gerardus Johannes Maria

    2006-01-01

    Cognitive Radio has been proposed as a promising technology to solve today’s spectrum scarcity problem. Cognitive Radio is able to sense the spectrum to find the free spectrum, which can be optimally used by Cognitive Radio without causing interference to the licensed user. In the scope of the

  5. Radio spectra of Gigahertz Peaked Spectrum radio sources

    NARCIS (Netherlands)

    deVries, WH; Barthel, PD; ODea, CP

    A well defined sample of 72 Gigahertz Peaked Spectrum radio sources is compiled, having turnover frequencies in the range of 0.5 - 10 GHz. Using this sample, the canonical GPS radio spectrum is constructed, which is found to have a constant shape, independent of AGN type, redshift or radio

  6. Spectrum management and radio resource management considering cognitive radio systems

    NARCIS (Netherlands)

    Haartsen, J.C.; Wieweg, Lasse; Huschke, Jörg

    2005-01-01

    International fora and some national administrations define a cognitive radio (CR) as a pioneering radio communication system that would be capable of altering and adapting its transmitter and receiver parameters based on communication and the exchange of information with related detectable radio

  7. 75 FR 10439 - Cognitive Radio Technologies and Software Defined Radios

    Science.gov (United States)

    2010-03-08

    ... COMMISSION 47 CFR Part 2 Cognitive Radio Technologies and Software Defined Radios AGENCY: Federal... of Engineering and Technology, (202) 418-7506, e-mail: [email protected] . SUPPLEMENTARY... Order 1. On March 17, 2005, the Commission adopted the Cognitive Radio Report and Order, 70 FR 23032...

  8. Non-coherent continuum scattering as a line polarization mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Del Pino Alemán, T.; Manso Sainz, R.; Trujillo Bueno, J., E-mail: tanausu@iac.es, E-mail: rsainz@iac.es, E-mail: jtb@iac.es [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)

    2014-03-20

    Line scattering polarization can be strongly affected by Rayleigh scattering at neutral hydrogen and Thomson scattering at free electrons. Often a depolarization of the continuum results, but the Doppler redistribution produced by the continuum scatterers, which are light (hence, fast), induces more complex interactions between the polarization in spectral lines and in the continuum. Here we formulate and solve the radiative transfer problem of scattering line polarization with non-coherent continuum scattering consistently. The problem is formulated within the spherical tensor representation of atomic and light polarization. The numerical method of solution is a generalization of the Accelerated Lambda Iteration that is applied to both the atomic system and the radiation field. We show that the redistribution of the spectral line radiation due to the non-coherence of the continuum scattering may modify the shape of the emergent fractional linear polarization patterns significantly, even yielding polarization signals above the continuum level in intrinsically unpolarizable lines.

  9. Continuum deformation of multi-agent systems

    CERN Document Server

    Rastgoftar, Hossein

    2016-01-01

    This monograph presents new algorithms for formation control of multi-agent systems (MAS) based on principles of continuum mechanics. Beginning with an overview of traditional methods, the author then introduces an innovative new approach whereby agents of an MAS are considered as particles in a continuum evolving in ℝn whose desired configuration is required to satisfy an admissible deformation function. The necessary theory and its validation on a mobile-agent-based swarm test bed are considered for two primary tasks: homogeneous transformation of the MAS and deployment of a random distribution of agents on a desired configuration. The framework for this model is based on homogeneous transformations for the evolution of an MAS under no inter-agent communication, local inter-agent communication, and intelligent perception by agents. Different communication protocols for MAS evolution, the robustness of tracking of a desired motion by an MAS evolving in ℝn, and the effect of communication delays in an MAS...

  10. Continuum robot arms inspired by cephalopods

    Science.gov (United States)

    Walker, Ian D.; Dawson, Darren M.; Flash, Tamar; Grasso, Frank W.; Hanlon, Roger T.; Hochner, Binyamin; Kier, William M.; Pagano, Christopher C.; Rahn, Christopher D.; Zhang, Qiming M.

    2005-05-01

    In this paper, we describe our recent results in the development of a new class of soft, continuous backbone ("continuum") robot manipulators. Our work is strongly motivated by the dexterous appendages found in cephalopods, particularly the arms and suckers of octopus, and the arms and tentacles of squid. Our ongoing investigation of these animals reveals interesting and unexpected functional aspects of their structure and behavior. The arrangement and dynamic operation of muscles and connective tissue observed in the arms of a variety of octopus species motivate the underlying design approach for our soft manipulators. These artificial manipulators feature biomimetic actuators, including artificial muscles based on both electro-active polymers (EAP) and pneumatic (McKibben) muscles. They feature a "clean" continuous backbone design, redundant degrees of freedom, and exhibit significant compliance that provides novel operational capacities during environmental interaction and object manipulation. The unusual compliance and redundant degrees of freedom provide strong potential for application to delicate tasks in cluttered and/or unstructured environments. Our aim is to endow these compliant robotic mechanisms with the diverse and dexterous grasping behavior observed in octopuses. To this end, we are conducting fundamental research into the manipulation tactics, sensory biology, and neural control of octopuses. This work in turn leads to novel approaches to motion planning and operator interfaces for the robots. The paper describes the above efforts, along with the results of our development of a series of continuum tentacle-like robots, demonstrating the unique abilities of biologically-inspired design.

  11. An Old Fogey’s History of Radio Jets

    Directory of Open Access Journals (Sweden)

    Ralph Spencer

    2017-10-01

    Full Text Available This paper describes a personal view of the discovery of radio jets in celestial radio sources. The existence of narrow, collimated optical features in distant objects has been known about since the early 20th century; however, the advent of radio astronomy in the 1940s and 1950s revealed the existence of a large number of discrete radio sources. The realization that many of these objects were not primarily stellar or local to our own galaxy, but rather extragalactic, followed the determination of accurate radio positions, enabling identifications with optical objects. High-resolution radio interferometers found that they were often compact, and with a double lobed structure, implying outflow from a central object. Shortly afterwards, accurate techniques for the measurement of polarization were developed. However it was not until the advent of synthesis instruments in the 1970s that radio images of the sources were produced, and the existence of radio jets firmly established and their polarization characteristics found.

  12. CLUSTERED RADIO INTERFEROMETRIC CALIBRATION

    NARCIS (Netherlands)

    Kazemi, S.; Yatawatta, S.; Zaroubi, S.

    2011-01-01

    This paper introduces an amendment to radio interferometric calibration of sources below the noise level. The main idea is to employ the information of the stronger sources' measured signals as a plug-in criterion to solve for the weaker ones. For this purpose, we construct a number of source

  13. Educational Broadcasting--Radio.

    Science.gov (United States)

    Ahamed, Uvais; Grimmett, George

    This manual is intended for those who must conduct educational radio broadcasting training courses in Asia-Pacific countries without the resources of experienced personnel, as well as for individuals to use in self-learning situations. The selection of material has been influenced by the need to use broadcasting resources effectively in programs…

  14. Radio Broadcast Technology

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 7; Issue 1. Radio Broadcast Technology. Harsh Vardhan. General Article Volume 7 Issue 1 January 2002 pp 53-63. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/007/01/0053-0063. Keywords. Hertzian ...

  15. Division x: Radio Astronomy

    NARCIS (Netherlands)

    Taylor, Russ; Chapman, Jessica; Rendong, Nan; Carilli, Christopher; Giovannini, Gabriele; Hills, Richard; Hirabayashi, Hisashi; Jonas, Justin; Lazio, Joseph; Morganti, Raffaella; Rubio, Monica; Shastri, Prajval

    This triennium has seen a phenomenal investment in development of observational radio astronomy facilities in all parts of the globe at a scale that significantly impacts the international community. This includes both major enhancements such as the transition from the VLA to the EVLA in North

  16. Torun Radio Astronomy Observatory

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    Torun Center for Astronomy is located at Piwnice, 15 km north of Torun, Poland. A part of the Faculty of Physics and Astronomy of the Nicolaus Copernicus University, it was created by the union of Torun Radio Astronomy Observatory (TRAO) and the Institute of Astronomy on 1 January 1997....

  17. Valuing commercial radio licences

    NARCIS (Netherlands)

    Kerste, M.; Poort, J.; van Eijk, N.

    2011-01-01

    Within the EU Regulatory Framework, licensees for commercial radio broadcasting may be charged a fee to ensure optimal allocation of scarce resources but not to maximize public revenues. In this paper, it is described how such a fee can be determined for the purpose of licence renewal or extension.

  18. Radio variability survey of very low luminosity protostars

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Minho; Kang, Miju [Korea Astronomy and Space Science Institute, 776 Daedeokdaero, Daejeon 305-348 (Korea, Republic of); Lee, Jeong-Eun, E-mail: minho@kasi.re.kr [Department of Astronomy and Space Science, Kyung Hee University, Yongin, Gyeonggi 446-701 (Korea, Republic of)

    2014-07-01

    Ten very low luminosity objects were observed multiple times in the 8.5 GHz continuum in search of protostellar magnetic activities. A radio outburst of IRAM 04191+1522 IRS was detected, and the variability timescale was about 20 days or shorter. The results of this survey and archival observations suggest that IRAM 04191+1522 IRS is in active states about half the time. Archival data show that L1014 IRS and L1148 IRS were detectable previously and suggest that at least 20%-30% of very low luminosity protostars are radio variables. Considering the variability timescale and flux level of IRAM 04191+1522 IRS and the previous detection of the circular polarization of L1014 IRS, the radio outbursts of these protostars are probably caused by magnetic flares. However, IRAM 04191+1522 IRS is too young and small to develop an internal convective dynamo. If the detected radio emission is indeed coming from magnetic flares, the discovery implies that the flares may be caused by the fossil magnetic fields of interstellar origin.

  19. A Radio Galaxy at z=5.19

    OpenAIRE

    van Breugel, Wil; De Breuck, Carlos; Stanford, S. A.; Stern, Dan; Rottgering, Huub; Miley, George

    1999-01-01

    We report the discovery of the most distant known AGN, the radio galaxy TN J0924-2201 at z = 5.19. The radio source was selected from a new sample of ultra-steep spectrum (USS) sources, has an extreme radio spectral index alpha_365MHz^1.4GHz = -1.63, and is identified at near-IR wavelengths with a very faint, K = 21.3 +- 0.3 object. Spectroscopic observations show a single emission line at lambda ~ 7530A, which we identify as Ly-alpha. The K-band image, sampling rest frame U-band, shows a mul...

  20. LOFAR discovery of an ultra-steep radio halo and giant head-tail radio galaxy in Abell 1132

    Science.gov (United States)

    Wilber, A.; Brüggen, M.; Bonafede, A.; Savini, F.; Shimwell, T.; van Weeren, R. J.; Rafferty, D.; Mechev, A. P.; Intema, H.; Andrade-Santos, F.; Clarke, A. O.; Mahony, E. K.; Morganti, R.; Prandoni, I.; Brunetti, G.; Röttgering, H.; Mandal, S.; de Gasperin, F.; Hoeft, M.

    2018-01-01

    Low-Frequency Array (LOFAR) observations at 144 MHz have revealed large-scale radio sources in the unrelaxed galaxy cluster Abell 1132. The cluster hosts diffuse radio emission on scales of ∼650 kpc near the cluster centre and a head-tail (HT) radio galaxy, extending up to 1 Mpc, south of the cluster centre. The central diffuse radio emission is not seen in NRAO VLA FIRST Survey, Westerbork Northern Sky Survey, nor in C & D array VLA observations at 1.4 GHz, but is detected in our follow-up Giant Meterwave Radio Telescope (GMRT) observations at 325 MHz. Using LOFAR and GMRT data, we determine the spectral index of the central diffuse emission to be α = -1.75 ± 0.19 (S ∝ να). We classify this emission as an ultra-steep spectrum radio halo and discuss the possible implications for the physical origin of radio haloes. The HT radio galaxy shows narrow, collimated emission extending up to 1 Mpc and another 300 kpc of more diffuse, disturbed emission, giving a full projected linear size of 1.3 Mpc - classifying it as a giant radio galaxy (GRG) and making it the longest HT found to date. The head of the GRG coincides with an elliptical galaxy (SDSS J105851.01+564308.5) belonging to Abell 1132. In our LOFAR image, there appears to be a connection between the radio halo and the GRG. The turbulence that may have produced the halo may have also affected the tail of the GRG. In turn, the GRG may have provided seed electrons for the radio halo.

  1. Broadly continuously tunable slot waveguide quantum cascade lasers based on a continuum-to-continuum active region design

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Bo; Zeng, Yong Quan; Liang, Guozhen; Hu, Xiao Nan; Rodriguez, Etienne [OPTIMUS, Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore 639798 (Singapore); CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553 (Singapore); Tao, Jin [OPTIMUS, Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore 639798 (Singapore); CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553 (Singapore); CDPT, Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore 637371 (Singapore); Wang, Qi Jie, E-mail: qjwang@ntu.edu.sg [OPTIMUS, Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore 639798 (Singapore); CDPT, Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore 637371 (Singapore)

    2015-09-14

    We report our progress in the development of broadly tunable single-mode slot waveguide quantum cascade lasers based on a continuum-to-continuum active region design. The electroluminescence spectrum of the continuum-to-continuum active region design has a full width at half maximum of 440 cm{sup −1} at center wavelength ∼10 μm at room temperature (300 K). Devices using the optimized slot waveguide structure and the continuum-to-continuum design can be tuned continuously with a lasing emission over 42 cm{sup −1}, from 9.74 to 10.16 μm, at room temperature by using only current tuning scheme, together with a side mode suppression ratio of above 15 dB within the whole tuning range.

  2. Ham Radio is Mir Magic.

    Science.gov (United States)

    Evans, Gary

    1997-01-01

    Presents a classroom activity in which students communicated with U.S. and Russian astronauts via ham radio while they were in orbit on the space station Mir. Gives suggestions for other ham radio classroom activities as well as names of organizations, publications, and grant programs that teachers can access to help in bring ham radio into their…

  3. ATLASGAL-selected massive clumps in the inner Galaxy. III. Dust continuum characterization of an evolutionary sample

    Science.gov (United States)

    König, C.; Urquhart, J. S.; Csengeri, T.; Leurini, S.; Wyrowski, F.; Giannetti, A.; Wienen, M.; Pillai, T.; Kauffmann, J.; Menten, K. M.; Schuller, F.

    2017-03-01

    Context. Massive-star formation and the processes involved are still poorly understood. The ATLASGAL survey provides an ideal basis for detailed studies of large numbers of massive-star forming clumps covering the whole range of evolutionary stages. The ATLASGAL Top100 is a sample of clumps selected by their infrared and radio properties to be representative for the whole range of evolutionary stages. Aims: The ATLASGAL Top100 sources are the focus of a number of detailed follow-up studies that will be presented in a series of papers. In the present work we use the dust continuum emission to constrain the physical properties of this sample and identify trends as a function of source evolution. Methods: We determine flux densities from mid-infrared to submillimeter wavelength (8-870 μm) images and use these values to fit their spectral energy distributions and determine their dust temperature and flux. Combining these with recent distances from the literature including maser parallax measurements we determine clump masses, luminosities and column densities. Results: We define four distinct source classes from the available continuum data and arrange these into an evolutionary sequence. This begins with sources found to be dark at 70 μm, followed by 24 μm weak sources with an embedded 70 μm source, continues through mid-infrared bright sources and ends with infrared bright sources associated with radio emission (i.e., H ii regions). We find trends for increasing temperature, luminosity, and column density with the proposed evolution sequence, confirming that this sample is representative of different evolutionary stages of massive star formation. Our sources span temperatures from approximately 11 to 41 K, with bolometric luminosities in the range 57 L⊙-3.8 × 106L⊙. The highest masses reach 4.3 × 104M⊙ and peak column densities up to 1.1 × 1024 cm-1, and therefore have the potential to form the most massive O-type stars. We show that at least 93 sources

  4. INOVASI RADIO KAMPUS (RANCANG BANGUN RADIO UDINUS DENGAN INOVASI TEKNOLOGI @RADIO

    Directory of Open Access Journals (Sweden)

    Wellia Shinta Sari

    2014-08-01

    Full Text Available Perkembangan Teknologi Informasi dan Komunikasi (TIK memaksa industri penyiaran untuk ikut menyesuaikan diri. Radio konvensional bisa jadi akan tertinggal jika tidak melakukan inovasi teknologi yang ada. Begitu juga dengan radio kampus, yang keberadaannya sangat dibutuhkan sebagai wadah kreativitas dan sarana pembelajaran di sebuah universitas, apalagi yang memiliki program studi penyiaran. Radio kampus Suara Dian yang masih konvensional sehingga hampir kehilangan eksistensinya harus segera dibenahi dan dihidupkan kembali dengan mengikuti perkembangan teknologi di era konvergensi. Metode Inovasi teknologi yang bisa dilakukan adalah dengan menggunakan teknologi @Radio Streaming, yang bukan sekedar streaming, tapi juga optimalisasi teknologi yang terintegrasi dinamis melalui RISE (Radio Broadcasting Integrated System. Dengan berbagai fitur unggul dari inovasi teknologi tersebut, maka diharapkan Radio kampus Udinus ”Suara Dian” dapat kembali hidup, berkembang dan lebih kompetitif ditengah industri penyiaran Radio. Kata kunci : radio, kampus, konvergensi, streaming.

  5. A continuum theory of edge dislocations

    Science.gov (United States)

    Berdichevsky, V. L.

    2017-09-01

    Continuum theory of dislocation aims to describe the behavior of large ensembles of dislocations. This task is far from completion, and, most likely, does not have a ;universal solution;, which is applicable to any dislocation ensemble. In this regards it is important to have guiding lines set by benchmark cases, where the transition from a discrete set of dislocations to a continuum description is made rigorously. Two such cases have been considered recently: equilibrium of dislocation walls and screw dislocations in beams. In this paper one more case is studied, equilibrium of a large set of 2D edge dislocations placed randomly in a 2D bounded region. The major characteristic of interest is energy of dislocation ensemble, because it determines the structure of continuum equations. The homogenized energy functional is obtained for the periodic dislocation ensembles with a random contents of the periodic cell. Parameters of the periodic structure can change slowly on distances of order of the size of periodic cells. The energy functional is obtained by the variational-asymptotic method. Equilibrium positions are local minima of energy. It is confirmed the earlier assertion that energy density of the system is the sum of elastic energy of averaged elastic strains and microstructure energy, which is elastic energy of the neutralized dislocation system, i.e. the dislocation system placed in a constant dislocation density field making the averaged dislocation density zero. The computation of energy is reduced to solution of a variational cell problem. This problem is solved analytically. The solution is used to investigate stability of simple dislocation arrays, i.e. arrays with one dislocation in the periodic cell. The relations obtained yield two outcomes: First, there is a state parameter of the system, dislocation polarization; averaged stresses affect only dislocation polarization and cannot change other characteristics of the system. Second, the structure of

  6. RADIO MONITORING OF THE PERIODICALLY VARIABLE IR SOURCE LRLL 54361: NO DIRECT CORRELATION BETWEEN THE RADIO AND IR EMISSIONS

    Energy Technology Data Exchange (ETDEWEB)

    Forbrich, Jan, E-mail: jan.forbrich@univie.ac.at [University of Vienna, Department of Astrophysics, Türkenschanzstraße 17, A-1180 Vienna (Austria); Rodríguez, Luis F.; Palau, Aina; Zapata, Luis A. [Instituto de Radioastronomía y Astrofísica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacán (Mexico); Muzerolle, James [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Gutermuth, Robert A. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)

    2015-11-20

    LRLL 54361 is an infrared source located in the star-forming region IC 348 SW. Remarkably, its infrared luminosity increases by a factor of 10 over roughly one week every 25.34 days. To understand the origin of these remarkable periodic variations, we obtained sensitive 3.3 cm JVLA radio continuum observations of LRLL 54361 and its surroundings in six different epochs: three of them during the IR-on state and three during the IR-off state. The radio source associated with LRLL 54361 remained steady and did not show a correlation with the IR variations. We suggest that the IR is tracing the results of fast (with a timescale of days) pulsed accretion from an unseen binary companion, while the radio traces an ionized outflow with an extent of ∼100 AU that smooths out the variability over a period of the order of a year. The average flux density measured in these 2014 observations, 27 ± 5 μJy, is about a factor of two less than that measured about 1.5 years before, 53 ± 11 μJy, suggesting that variability in the radio is present, but over larger timescales than in the IR. We discuss other sources in the field, in particular two infrared/X-ray stars that show rapidly varying gyrosynchrotron emission.

  7. Configurable SDR Operation for Cognitive Radio Applications using GNU Radio and the Universal Software Radio Peripheral

    OpenAIRE

    Scaperoth, David Alan

    2007-01-01

    With interoperability issues plaguing emergency responders throughout the country, Cognitive Radio (CR) offers a unique solution to streamline communication between police, Emergency Medical Technicians (EMT), and military officers. Using Software Defined Radio (SDR) technology, a flexible radio platform can be potentially configured using a Cognitive Engine (CE) to transmit and receive many different incompatible radio standards. In this thesis, an interface between a Cognitive Engine and...

  8. A Continuum of Nonclinical Eating Disorders: A Review of Behavioral and Psychological Correlates and Suggestions for Intervention.

    Science.gov (United States)

    Kalodner, Cynthia R.; Scarano, Gina M.

    1992-01-01

    Reviews research which distinguishes various points along the continuum from normal eating habits to clinically diagnosed eating disorders. Focuses on nonclinical intermediate points and proposes intervention strategies for women experiencing difficulties with weight, body image, and/or eating. Contends further research is necessary for greater…

  9. Variational continuum multiphase poroelasticity theory and applications

    CERN Document Server

    Serpieri, Roberto

    2017-01-01

    This book collects the theoretical derivation of a recently presented general variational macroscopic continuum theory of multiphase poroelasticity (VMTPM), together with its applications to consolidation and stress partitioning problems of interest in several applicative engineering contexts, such as in geomechanics and biomechanics. The theory is derived based on a purely-variational deduction, rooted in the least-Action principle, by considering a minimal set of kinematic descriptors. The treatment herein considered keeps a specific focus on the derivation of most general medium-independent governing equations. It is shown that VMTPM recovers paradigms of consolidated use in multiphase poroelasticity such as Terzaghi's stress partitioning principle and Biot's equations for wave propagation. In particular, the variational treatment permits the derivation of a general medium-independent stress partitioning law, and the proposed variational theory predicts that the external stress, the fluid pressure, and the...

  10. Embodiment design of soft continuum robots

    Directory of Open Access Journals (Sweden)

    Rongjie Kang

    2016-04-01

    Full Text Available This article presents the results of a multidisciplinary project where mechatronic engineers worked alongside biologists to develop a soft robotic arm that captures key features of octopus anatomy and neurophysiology. The concept of embodiment (the dynamic coupling between sensory-motor control, anatomy, materials and environment that allows for the animal to achieve adaptive behaviours is used as a starting point for the design process but tempered by current engineering technologies and approaches. In this article, the embodied design requirements are first discussed from a robotic viewpoint by taking into account real-life engineering limitations; then, the motor control schemes inspired by octopus nervous system are investigated. Finally, the mechanical and control design of a prototype is presented that appropriately blends bio-inspiration and engineering limitations. Simulated and experimental results show that the developed continuum robotic arm is able to reproduce octopus-like motions for bending, reaching and grasping.

  11. Atomic size effects in continuum modeling

    Science.gov (United States)

    Ratsch, C.; Kang, M.; Caflisch, R. E.

    2001-08-01

    Continuum modeling of many physical systems typically assumes that the spatial extent of an atom is small compared to the quantities of interest and can therefore be neglected. We show that this is valid only asymptotically. For many applications of practical interest, the spatial extent of a discrete atom cannot be neglected. We have developed a model for the description of epitaxial growth based on the levelset method, and find that we can accurately predict quantities such as the island densities, if we implement boundary conditions in a region with atomic width, rather than just on a line without any spatial extent. Only in the limit of very large islands and island spacings can this be neglected.

  12. Continuum Reverberation Mapping of AGN Accretion Disks

    Directory of Open Access Journals (Sweden)

    Michael M. Fausnaugh

    2017-12-01

    Full Text Available We show recent detections of inter-band continuum lags in three AGN (NGC 5548, NGC 2617, and MCG+08-11-011, which provide new constraints on the temperature profiles and absolute sizes of the accretion disks. We find lags larger than would be predicted for standard geometrically thin, optically thick accretion disks by factors of 2.3–3.3. For NGC 5548, the data span UV through optical/near-IR wavelengths, and we are able to discern a steeper temperature profile than the T ~ R−3/4 expected for a standard thin disk. Using a physical model, we are also able to estimate the inclinations of the disks for two objects. These results are similar to those found from gravitational microlensing of strongly lensed quasars, and provide a complementary approach for investigating the accretion disk structure in local, low luminosity AGN.

  13. A Threshold Continuum for Aeolian Sand Transport

    Science.gov (United States)

    Swann, C.; Ewing, R. C.; Sherman, D. J.

    2015-12-01

    The threshold of motion for aeolian sand transport marks the initial entrainment of sand particles by the force of the wind. This is typically defined and modeled as a singular wind speed for a given grain size and is based on field and laboratory experimental data. However, the definition of threshold varies significantly between these empirical models, largely because the definition is based on visual-observations of initial grain movement. For example, in his seminal experiments, Bagnold defined threshold of motion when he observed that 100% of the bed was in motion. Others have used 50% and lesser values. Differences in threshold models, in turn, result is large errors in predicting the fluxes associated with sand and dust transport. Here we use a wind tunnel and novel sediment trap to capture the fractions of sand in creep, reptation and saltation at Earth and Mars pressures and show that the threshold of motion for aeolian sand transport is best defined as a continuum in which grains progress through stages defined by the proportion of grains in creep and saltation. We propose the use of scale dependent thresholds modeled by distinct probability distribution functions that differentiate the threshold based on micro to macro scale applications. For example, a geologic timescale application corresponds to a threshold when 100% of the bed in motion whereas a sub-second application corresponds to a threshold when a single particle is set in motion. We provide quantitative measurements (number and mode of particle movement) corresponding to visual observations, percent of bed in motion and degrees of transport intermittency for Earth and Mars. Understanding transport as a continuum provides a basis for revaluating sand transport thresholds on Earth, Mars and Titan.

  14. Understanding and Managing the Ictal-Interictal Continuum in Neurocritical Care.

    Science.gov (United States)

    Sivaraju, Adithya; Gilmore, Emily J

    2016-02-01

    Continuous electroencephalographic (EEG) monitoring has become an invaluable tool for the assessment of brain function in critically ill patients. However, interpretation of EEG waveforms, especially in the intensive care unit (ICU) setting is fraught with ambiguity. The term ictal-interictal continuum encompasses EEG patterns that are potentially harmful and can cause neuronal injury. There are no clear guidelines on how to treat EEG patterns that lie on this continuum. We advocate the following approaches in a step wise manner: (1) identify and exclude clear electrographic seizures and status epilepticus (SE), i.e., generalized spike-wave discharges at 3/s or faster; and clearly evolving discharges of any type (rhythmic, periodic, fast activity), whether focal or generalized; (2) exclude clear interictal patterns, i.e., spike-wave discharges, periodic discharges, and rhythmic patterns at 1/s or slower with no evolution, unless accompanied by a clear clinical correlate, which would make them ictal regardless of the frequency; (3) consider any EEG patterns that lie in between the above two categories as being on the ictal-interictal continuum; (4) compare the electrographic pattern of the ictal-incterictal continuum to the normal background and unequivocal seizures (if present) from the same patient; (5) when available, correlate ictal-interictal continuum pattern with other markers of neuronal injury such as neuronal specific enolase (NSE) levels, brain imaging findings, depth electrode recordings, data from microdialysis, intracranial pressure fluctuations, and brain oxygen measurement; and (6) perform a diagnostic trial with preferably a nonsedating antiepileptic drug with the endpoint being both clinical and electrographic improvement. Minimize the use of anesthetics or multiple AEDs unless there is clear supporting evidence from ancillary tests or worsening of the EEG patterns over time, which could indicate possible neuronal injury.

  15. The Concept of 'Radio Music'

    DEFF Research Database (Denmark)

    Fjeldsøe, Michael

    2016-01-01

    , educational and didactic effort which would enlighten all of society. For a while it seemed that radio music was considered a genre of its own. To fulfil its function, radio music had to consider technical limitations as well as the educational level and listening modes of the new mass audience. Public radio......, as discussed by Kurt Weill and Paul Hindemith, was at first greeted with great expectations, but soon a more realistic attitude prevailed. Weill, himself a radio critic as well, composed Der Lindberghflug (1929) as a piece of ‘radio music theatre’, but then changed some of its features in order to turn...... it into a didactical play for amateurs, a so-called Lehrstück. The article will present the concept of ‘radio music’ developed within German Neue Sachlichkeit and discuss the relevance of such a concept for current research in the field of radio and music....

  16. Continuum Damage Mechanics A Continuum Mechanics Approach to the Analysis of Damage and Fracture

    CERN Document Server

    Murakami, Sumio

    2012-01-01

    Recent developments in engineering and technology have brought about serious and enlarged demands for reliability, safety and economy in wide range of fields such as aeronautics, nuclear engineering, civil and structural engineering, automotive and production industry.  This, in turn, has caused more interest in continuum damage mechanics and its engineering applications.   This book aims to give a concise overview of the current state of damage mechanics, and then to show the fascinating possibility of this promising branch of mechanics, and to provide researchers, engineers and graduate students with an intelligible and self-contained textbook.   The book consists of two parts and an appendix.  Part I  is concerned with the foundation of continuum damage mechanics.  Basic concepts of material damage and the mechanical representation of damage state of various kinds are described in Chapters 1 and 2.  In Chapters 3-5, irreversible thermodynamics, thermodynamic constitutive theory and its application ...

  17. Hybrid continuum-atomistic approach to model electrokinetics in nanofluidics

    Energy Technology Data Exchange (ETDEWEB)

    Amani, Ehsan, E-mail: eamani@aut.ac.ir; Movahed, Saeid, E-mail: smovahed@aut.ac.ir

    2016-06-07

    In this study, for the first time, a hybrid continuum-atomistic based model is proposed for electrokinetics, electroosmosis and electrophoresis, through nanochannels. Although continuum based methods are accurate enough to model fluid flow and electric potential in nanofluidics (in dimensions larger than 4 nm), ionic concentration is too low in nanochannels for the continuum assumption to be valid. On the other hand, the non-continuum based approaches are too time-consuming and therefore is limited to simple geometries, in practice. Here, to propose an efficient hybrid continuum-atomistic method of modelling the electrokinetics in nanochannels; the fluid flow and electric potential are computed based on continuum hypothesis coupled with an atomistic Lagrangian approach for the ionic transport. The results of the model are compared to and validated by the results of the molecular dynamics technique for a couple of case studies. Then, the influences of bulk ionic concentration, external electric field, size of nanochannel, and surface electric charge on the electrokinetic flow and ionic mass transfer are investigated, carefully. The hybrid continuum-atomistic method is a promising approach to model more complicated geometries and investigate more details of the electrokinetics in nanofluidics. - Highlights: • A hybrid continuum-atomistic model is proposed for electrokinetics in nanochannels. • The model is validated by molecular dynamics. • This is a promising approach to model more complicated geometries and physics.

  18. The urban watershed continuum: evolving spatial and temporal dimensions

    Science.gov (United States)

    Sujay S. Kaushal; Kenneth T. Belt

    2012-01-01

    Urban ecosystems are constantly evolving, and they are expected to change in both space and time with active management or degradation. An urban watershed continuum framework recognizes a continuum of engineered and natural hydrologic flowpaths that expands hydrologic networks in ways that are seldom considered. It recognizes that the nature of hydrologic connectivity...

  19. Continuum Thinking and the Contexts of Personal Information Management

    Science.gov (United States)

    Huvila, Isto; Eriksen, Jon; Häusner, Eva-Maria; Jansson, Ina-Maria

    2014-01-01

    Introduction: Recent personal information management literature has underlined the significance of the contextuality of personal information and its use. The present article discusses the applicability of the records continuum model and its generalisation, continuum thinking, as a theoretical framework for explicating the overlap and evolution of…

  20. Continuum of Counseling Goals: A Framework for Differentiating Counseling Strategies.

    Science.gov (United States)

    Bruce, Paul

    1984-01-01

    Presents counseling goals in a developmental continuum similar in concept to Maslow's hierarchy of needs. Discusses ego development goals, socialization goals, developmental goals, self-esteem goals, and self-realization goals and describes characteristics and implications of the continuum. (JAC)

  1. Points-Based Safe Path Planning of Continuum Robots

    Directory of Open Access Journals (Sweden)

    Khuram Shahzad

    2015-07-01

    Full Text Available Continuum robots exhibit great potential in a number of challenging applications where traditional rigid link robots pose certain limitations, e.g., working in unstructured environments. In order to enable the usage of continuum robots in safety-critical applications, such as surgery and nuclear decontamination, it is extremely important to ensure a safe path for the robot's movement. Existing algorithms for continuum robot path planning have certain limitations that need to be addressed. These include the fact that none of the algorithms provide safety assurance parameters and control for path planning. They are computationally expensive, applicable to a specific type of continuum robots, and mostly they do not incorporate design and kinematics constraints. In this paper, we propose a points-based path planning (PoPP algorithm for continuum robots that computes the path by imposing safety constraints and improves upon the limitations of existing approaches. In the algorithm, we exploit the constant curvature-bending property of continuum robots in their path planning process. The algorithm is computationally efficient and provides a good tradeoff between accuracy and efficiency that can be implemented to enable the safety-critical application of continuum robots. This algorithm also provides information regarding path volume and flexibility in movement. Simulation results confirm that the algorithm possesses promising potential for all types of continuum robots (following the constant curvature-bending property. We believe that this effectively balances the desired safety and efficiency requirements.

  2. Teaching Continuum Mechanics in a Mechanical Engineering Program

    Science.gov (United States)

    Liu, Yucheng

    2011-01-01

    This paper introduces a graduate course, continuum mechanics, which is designed for and taught to graduate students in a Mechanical Engineering (ME) program. The significance of continuum mechanics in engineering education is demonstrated and the course structure is described. Methods used in teaching this course such as topics, class…

  3. Tools of radio astronomy

    CERN Document Server

    Wilson, Thomas L; Hüttemeister, Susanne

    2009-01-01

    The recent years have seen breathtaking progress in technology, especially in the receiver and digital technologies relevant for radio astronomy, which has at the same time advanced to shorter wavelengths. This is the updated and completely revised 5th edition of the most used introductory text in radio astronomy. It presents a unified treatment of the entire field from centimeter to sub-millimeter wavelengths. Topics covered include instruments, sensitivity considerations, observational methods and interpretations of the data recorded with both single dishes and interferometers. This text is useful to both students and experienced practicing astronomers. Besides making major updates and additions throughout the book, the authors have re-organized a number of chapters to more clearly separate basic theory from rapidly evolving practical aspects. Further, problem sets have been added at the end of each chapter.

  4. Classifying Radio Galaxies with the Convolutional Neural Network

    Science.gov (United States)

    Aniyan, A. K.; Thorat, K.

    2017-06-01

    We present the application of a deep machine learning technique to classify radio images of extended sources on a morphological basis using convolutional neural networks (CNN). In this study, we have taken the case of the Fanaroff-Riley (FR) class of radio galaxies as well as radio galaxies with bent-tailed morphology. We have used archival data from the Very Large Array (VLA)—Faint Images of the Radio Sky at Twenty Centimeters survey and existing visually classified samples available in the literature to train a neural network for morphological classification of these categories of radio sources. Our training sample size for each of these categories is ˜200 sources, which has been augmented by rotated versions of the same. Our study shows that CNNs can classify images of the FRI and FRII and bent-tailed radio galaxies with high accuracy (maximum precision at 95%) using well-defined samples and a “fusion classifier,” which combines the results of binary classifications, while allowing for a mechanism to find sources with unusual morphologies. The individual precision is highest for bent-tailed radio galaxies at 95% and is 91% and 75% for the FRI and FRII classes, respectively, whereas the recall is highest for FRI and FRIIs at 91% each, while the bent-tailed class has a recall of 79%. These results show that our results are comparable to that of manual classification, while being much faster. Finally, we discuss the computational and data-related challenges associated with the morphological classification of radio galaxies with CNNs.

  5. Radio Frequency Spectrum Management

    Science.gov (United States)

    1980-03-01

    limits, emmission standards, etc., cover many pages. Other available non-technical policy statements are of the motherhood-and-apple-pie ilk. Further...and 2) by allowing the onscene commander who is acutely aware of the radio frequency emmission environment in his area to make assignments. The author...need for investment in specific human capi- tal vice on the job experience, it will never eliminate it. Rather vice education and training in

  6. Programme driven music radio

    OpenAIRE

    Hayes, Conor; Cunningham, Padraig; Clerkin, Patrick; Grimaldi, Marco

    2002-01-01

    This paper describes the operation of and research behind a networked application for the delivery of personalised streams of music at Trinity College Dublin. Smart Radio is a web based client-server application that uses streaming audio technology and recommendation techniques to allow users build, manage and share music programmes. While it is generally acknowledged that music distribution over the web will dramatically change how the music industry operates, there are ...

  7. Image quality assessment of a 1.5T dedicated magnetic resonance-simulator for radiotherapy with a flexible radio frequency coil setting using the standard American College of Radiology magnetic resonance imaging phantom test

    Science.gov (United States)

    Wong, Oi Lei; Yu, Siu Ki; Cheung, Kin Yin

    2017-01-01

    Background A flexible RF coil setting has to be used on an MR-simulator (MR-sim) in the head and neck simulation scan for radiotherapy (RT) purpose, while the image quality might be compromised due to the sub-optimized flexible coil compared to the normal diagnostic radiological (DR) head coil. In this study, we assessed the image quality of an MR-sim by conducting the standard American College of Radiology (ACR) MRI phantom test on a 1.5T MR-sim under RT-setting and comparing it to DR-setting. Methods A large ACR MRI phantom was carefully positioned, aligned and scanned 9 times for each under RT- and DR-setting on a 1.5T MR-sim, following the ACR scanning instruction. Images were analyzed following the ACR guidance. Measurement results under two coil settings were quantitatively compared. Inter-observer disagreements under RT-setting between two physicists were compared using Bland-Altman (BA) analysis and intra-class correlation coefficient (ICC). Results The MR-sim with RT-setting obtained sufficiently good image quality to pass all ACR recommended criteria. No significant difference was found in phantom length accuracy, high-contrast spatial resolution, slice thickness accuracy, slice position accuracy, and percent-signal ghosting. RT-setting significantly under-performed in low-contrast object detectability, while better performed in image intensity uniformity. BA analysis showed that 95% limit of agreement and biases of phantom test measurement under RT-setting between two observers were very small. Excellent inter-observer agreement (ICC >0.75) was achieved in all measurements except for slice thickness accuracy (ICC =0.42, moderate agreement) under RT-setting. Conclusions Very good and highly reproducible image quality could be achieved on a 1.5T MR-sim with a flexible coil setting as revealed by the standard ACR MRI phantom test. The flexible RT-setting compromised in image signal-to-noise ratio (SNR) compared to the normal DR-setting, and resulted in

  8. Image quality assessment of a 1.5T dedicated magnetic resonance-simulator for radiotherapy with a flexible radio frequency coil setting using the standard American College of Radiology magnetic resonance imaging phantom test.

    Science.gov (United States)

    Wong, Oi Lei; Yuan, Jing; Yu, Siu Ki; Cheung, Kin Yin

    2017-04-01

    A flexible RF coil setting has to be used on an MR-simulator (MR-sim) in the head and neck simulation scan for radiotherapy (RT) purpose, while the image quality might be compromised due to the sub-optimized flexible coil compared to the normal diagnostic radiological (DR) head coil. In this study, we assessed the image quality of an MR-sim by conducting the standard American College of Radiology (ACR) MRI phantom test on a 1.5T MR-sim under RT-setting and comparing it to DR-setting. A large ACR MRI phantom was carefully positioned, aligned and scanned 9 times for each under RT- and DR-setting on a 1.5T MR-sim, following the ACR scanning instruction. Images were analyzed following the ACR guidance. Measurement results under two coil settings were quantitatively compared. Inter-observer disagreements under RT-setting between two physicists were compared using Bland-Altman (BA) analysis and intra-class correlation coefficient (ICC). The MR-sim with RT-setting obtained sufficiently good image quality to pass all ACR recommended criteria. No significant difference was found in phantom length accuracy, high-contrast spatial resolution, slice thickness accuracy, slice position accuracy, and percent-signal ghosting. RT-setting significantly under-performed in low-contrast object detectability, while better performed in image intensity uniformity. BA analysis showed that 95% limit of agreement and biases of phantom test measurement under RT-setting between two observers were very small. Excellent inter-observer agreement (ICC >0.75) was achieved in all measurements except for slice thickness accuracy (ICC =0.42, moderate agreement) under RT-setting. Very good and highly reproducible image quality could be achieved on a 1.5T MR-sim with a flexible coil setting as revealed by the standard ACR MRI phantom test. The flexible RT-setting compromised in image signal-to-noise ratio (SNR) compared to the normal DR-setting, and resulted in reduced low-contrast object detectability.

  9. GIANT LOBES OF CENTAURUS A RADIO GALAXY OBSERVED WITH THE SUZAKU X-RAY SATELLITE

    Energy Technology Data Exchange (ETDEWEB)

    Stawarz, L.; Gandhi, P.; Takahashi, T.; Takei, Y. [Institute of Space and Astronautical Science JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Tanaka, Y. T.; Fukazawa, Y. [Department of Physical Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Madejski, G. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); O' Sullivan, S. P. [Sydney Institute for Astronomy, School of Physics A28, University of Sydney, Sydney, NSW 2006 (Australia); Cheung, C. C. [National Academy of Sciences, Washington, DC 20001 (United States); Feain, I. J. [CSIRO Astronomy and Space Science, ATNF, P.O. Box 76, Epping, NSW 1710 (Australia); Hardcastle, M. J. [School of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield AL10 9AB (United Kingdom); Kataoka, J.; Takeuchi, Y. [Research Institute for Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169-8555 (Japan); Ostrowski, M. [Astronomical Observatory, Jagiellonian University, ul. Orla 171, 30-244 Krakow (Poland); Reville, B. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Siemiginowska, A. [Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Simionescu, A.; Werner, N., E-mail: stawarz@astro.isas.jaxa.jp [KIPAC, Stanford University, 452 Lomita Mall, Stanford, CA 94305 (United States)

    2013-03-20

    We report on Suzaku observations of selected regions within the southern giant lobe of the radio galaxy Centaurus A. In our analysis we focus on distinct X-ray features detected with the X-ray Imaging Spectrometer within the range 0.5-10 keV, some of which are likely associated with fine structure of the lobe revealed by recent high-quality radio intensity and polarization maps. With the available photon statistics, we find that the spectral properties of the detected X-ray features are equally consistent with thermal emission from hot gas with temperatures kT > 1 keV, or with a power-law radiation continuum characterized by photon indices {Gamma} {approx} 2.0 {+-} 0.5. However, the plasma parameters implied by these different models favor a synchrotron origin for the analyzed X-ray spots, indicating that a very efficient acceleration of electrons up to {approx}> 10 TeV energies is taking place within the giant structure of Centaurus A, albeit only in isolated and compact regions associated with extended and highly polarized radio filaments. We also present a detailed analysis of the diffuse X-ray emission filling the whole field of view of the instrument, resulting in a tentative detection of a soft excess component best fitted by a thermal model with a temperature of kT {approx} 0.5 keV. The exact origin of the observed excess remains uncertain, although energetic considerations point to thermal gas filling the bulk of the volume of the lobe and mixed with the non-thermal plasma, rather than to the alternative scenario involving a condensation of the hot intergalactic medium around the edges of the expanding radio structure. If correct, this would be the first detection of the thermal content of the extended lobes of a radio galaxy in X-rays. The corresponding number density of the thermal gas in such a case is n{sub g} {approx} 10{sup -4} cm{sup -3}, while its pressure appears to be in almost exact equipartition with the volume-averaged non-thermal pressure

  10. Giant Lobes of Centaurus A Radio Galaxy Observed with the Suzaku X-Ray Satellite

    Science.gov (United States)

    Stawarz, Ł.; Tanaka, Y. T.; Madejski, G.; O'Sullivan, S. P.; Cheung, C. C.; Feain, I. J.; Fukazawa, Y.; Gandhi, P.; Hardcastle, M. J.; Kataoka, J.; Ostrowski, M.; Reville, B.; Siemiginowska, A.; Simionescu, A.; Takahashi, T.; Takei, Y.; Takeuchi, Y.; Werner, N.

    2013-03-01

    We report on Suzaku observations of selected regions within the southern giant lobe of the radio galaxy Centaurus A. In our analysis we focus on distinct X-ray features detected with the X-ray Imaging Spectrometer within the range 0.5-10 keV, some of which are likely associated with fine structure of the lobe revealed by recent high-quality radio intensity and polarization maps. With the available photon statistics, we find that the spectral properties of the detected X-ray features are equally consistent with thermal emission from hot gas with temperatures kT > 1 keV, or with a power-law radiation continuum characterized by photon indices Γ ~ 2.0 ± 0.5. However, the plasma parameters implied by these different models favor a synchrotron origin for the analyzed X-ray spots, indicating that a very efficient acceleration of electrons up to >~ 10 TeV energies is taking place within the giant structure of Centaurus A, albeit only in isolated and compact regions associated with extended and highly polarized radio filaments. We also present a detailed analysis of the diffuse X-ray emission filling the whole field of view of the instrument, resulting in a tentative detection of a soft excess component best fitted by a thermal model with a temperature of kT ~ 0.5 keV. The exact origin of the observed excess remains uncertain, although energetic considerations point to thermal gas filling the bulk of the volume of the lobe and mixed with the non-thermal plasma, rather than to the alternative scenario involving a condensation of the hot intergalactic medium around the edges of the expanding radio structure. If correct, this would be the first detection of the thermal content of the extended lobes of a radio galaxy in X-rays. The corresponding number density of the thermal gas in such a case is ng ~ 10-4 cm-3, while its pressure appears to be in almost exact equipartition with the volume-averaged non-thermal pressure provided by the radio-emitting electrons and the lobes

  11. Radio Telescope Reflectors

    Science.gov (United States)

    Baars, Jacob W. M.; Kärcher, Hans J.

    2017-11-01

    This book demonstrates how progress in radio astronomy is intimately linked to the development of reflector antennas of increasing size and precision. The authors describe the design and construction of major radio telescopes as those in Dwingeloo, Jodrell Bank, Parkes, Effelsberg and Green Bank since 1950 up to the present as well as millimeter wavelength telescopes as the 30m MRT of IRAM in Spain, the 50m LMT in Mexico and the ALMA submillimeter instrument. The advances in methods of structural design and coping with environmental influences (wind, temperature, gravity) as well as application of new materials are explained in a non-mathematical, descriptive and graphical way along with the story of the telescopes. Emphasis is placed on the interplay between astronomical and electromagnetic requirements and structural, mechanical and control solutions. A chapter on management aspects of large telescope projects closes the book. The authors address a readership with interest in the progress of engineering solutions applied to the development of radio telescope reflectors and ground station antennas for satellite communication and space research. The book will also be of interest to historians of science and engineering with an inclination to astronomy.

  12. Danmarks Radios stemmer

    DEFF Research Database (Denmark)

    Lawaetz, Anna

    kanalspeakerne kändisser, hvis fortalelser i æteren såvel som private gøren og laden blev fulgt nøje i dagspressen. Anna Lawaetz har med ph.d.-afhandlingen Danmarks Radios stemmer med udgangspunkt i kanalspeakerne på P1 i perioden 1925-2012 gennem empiriske studier kortlagt fortællingen om institutionens stemmer...... – nøje udvalgte ikke-fiktionsstemmer i Danmarks Radio igennem tiden. Samtidig har hun lavet en konkret analyse af stemmerne baseret på både akustiske målinger og kategorisering af oplevelsen af stemmerne. Fx taler kanalspeakerne på P1 i dag ikke hurtigere end tidligere, men pauserne er blevet kortere...... datamængder kræver udvikling af nye metoder. Den metodiske udvikling har her været baseret på optagelser af stemmer for at undersøge hvordan man videnskabeligt kan arbejde med optagelser af stemmer som mere end teksttransskriptioner inden for det kulturvidenskabelige felt med afsæt i Danmarks Radios...

  13. The FIRST radio survey: The K-z diagram of FIRST radio sources identified in the Bo\\"{o}tes and Cetus fields

    OpenAIRE

    Bouchefry, Khadija EL

    2009-01-01

    This paper presents the Hubble diagram (K-z relation) for FIRST (Faint Images of the Radio Sky at 20 cm) radio sources identified in the Bootes and Cetus fields. The correlation between the K magnitude of the FIRST-NDWFS sample and the photometric redshifts found to be linear. The dispersion about the best fit line is given by 1.53 for the whole sample and 0.75 at z>1. The paper also presents a composite K-z diagram of FIRST radio sources and low-frequency selected radio samples with progress...

  14. Subarcsec optical and radio obsercations of the gravitationally ...

    African Journals Online (AJOL)

    Optical observations of the multiple-component gravitational lens candidate B1422+23.1 using the 2.5m Nordic Optical Telescope and a MERLIN image at 1658 MHz are presented. The radio image at L-band and B, V, R and I band images with a 0.6 arcsec seeing resolve the components. These observations show that the ...

  15. The Lyman Continuum Escape Fraction of Emission Line-selected z ∼ 2.5 Galaxies Is Less Than 15%

    Energy Technology Data Exchange (ETDEWEB)

    Rutkowski, Michael J.; Hayes, Matthew [Department of Astronomy, AlbaNova University Centre, Stockholm University, SE-10691 Stockholm (Sweden); Scarlata, Claudia; Mehta, Vihang [Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Henry, Alaina; Hathi, Nimish; Koekemoer, Anton M. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Cohen, Seth; Windhorst, Rogier [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85281 (United States); Teplitz, Harry I. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Haardt, Francesco [DiSAT, Università dellInsubria, via Valleggio 11, I-22100 Como (Italy); Siana, Brian [Department of Physics, University of California, Riverside, CA 92521 (United States)

    2017-06-01

    Recent work suggests that strong emission line, star-forming galaxies (SFGs) may be significant Lyman continuum leakers. We combine archival Hubble Space Telescope broadband ultraviolet and optical imaging (F275W and F606W, respectively) with emission line catalogs derived from WFC3 IR G141 grism spectroscopy to search for escaping Lyman continuum (LyC) emission from homogeneously selected z ∼ 2.5 SFGs. We detect no escaping Lyman continuum from SFGs selected on [O ii] nebular emission ( N = 208) and, within a narrow redshift range, on [O iii]/[O ii]. We measure 1 σ upper limits to the LyC escape fraction relative to the non-ionizing UV continuum from [O ii] emitters, f {sub esc} ≲ 5.6%, and strong [O iii]/[O ii] > 5 ELGs, f {sub esc} ≲ 14.0%. Our observations are not deep enough to detect f {sub esc} ∼ 10% typical of low-redshift Lyman continuum emitters. However, we find that this population represents a small fraction of the star-forming galaxy population at z ∼ 2. Thus, unless the number of extreme emission line galaxies grows substantially to z ≳ 6, such galaxies may be insufficient for reionization. Deeper survey data in the rest-frame ionizing UV will be necessary to determine whether strong line ratios could be useful for pre-selecting LyC leakers at high redshift.

  16. The Lyman Continuum Escape Fraction of Emission Line-selected z ˜ 2.5 Galaxies Is Less Than 15%

    Science.gov (United States)

    Rutkowski, Michael J.; Scarlata, Claudia; Henry, Alaina; Hayes, Matthew; Mehta, Vihang; Hathi, Nimish; Cohen, Seth; Windhorst, Rogier; Koekemoer, Anton M.; Teplitz, Harry I.; Haardt, Francesco; Siana, Brian

    2017-06-01

    Recent work suggests that strong emission line, star-forming galaxies (SFGs) may be significant Lyman continuum leakers. We combine archival Hubble Space Telescope broadband ultraviolet and optical imaging (F275W and F606W, respectively) with emission line catalogs derived from WFC3 IR G141 grism spectroscopy to search for escaping Lyman continuum (LyC) emission from homogeneously selected z ˜ 2.5 SFGs. We detect no escaping Lyman continuum from SFGs selected on [O II] nebular emission (N = 208) and, within a narrow redshift range, on [O III]/[O II]. We measure 1σ upper limits to the LyC escape fraction relative to the non-ionizing UV continuum from [O II] emitters, f esc ≲ 5.6%, and strong [O III]/[O II] > 5 ELGs, f esc ≲ 14.0%. Our observations are not deep enough to detect f esc ˜ 10% typical of low-redshift Lyman continuum emitters. However, we find that this population represents a small fraction of the star-forming galaxy population at z ˜ 2. Thus, unless the number of extreme emission line galaxies grows substantially to z ≳ 6, such galaxies may be insufficient for reionization. Deeper survey data in the rest-frame ionizing UV will be necessary to determine whether strong line ratios could be useful for pre-selecting LyC leakers at high redshift.

  17. Powerful Radio Burst Indicates New Astronomical Phenomenon

    Science.gov (United States)

    2007-09-01

    Astronomers studying archival data from an Australian radio telescope have discovered a powerful, short-lived burst of radio waves that they say indicates an entirely new type of astronomical phenomenon. Region of Strong Radio Burst Visible-light (negative greyscale) and radio (contours) image of Small Magellanic Cloud and area where burst originated. CREDIT: Lorimer et al., NRAO/AUI/NSF Click on image for high-resolution file ( 114 KB) "This burst appears to have originated from the distant Universe and may have been produced by an exotic event such as the collision of two neutron stars or the death throes of an evaporating black hole," said Duncan Lorimer, Assistant Professor of Physics at West Virginia University (WVU) and the National Radio Astronomy Observatory (NRAO). The research team led by Lorimer consists of Matthew Bailes of Swinburne University in Australia, Maura McLaughlin of WVU and NRAO, David Narkevic of WVU, and Fronefield Crawford of Franklin and Marshall College in Lancaster, Pennsylvania. The astronomers announced their findings in the September 27 issue of the online journal Science Express. The startling discovery came as WVU undergraduate student David Narkevic re-analyzed data from observations of the Small Magellanic Cloud made by the 210-foot Parkes radio telescope in Australia. The data came from a survey of the Magellanic Clouds that included 480 hours of observations. "This survey had sought to discover new pulsars, and the data already had been searched for the type of pulsating signals they produce," Lorimer said. "We re-examined the data, looking for bursts that, unlike the usual ones from pulsars, are not periodic," he added. The survey had covered the Magellanic Clouds, a pair of small galaxies in orbit around our own Milky Way Galaxy. Some 200,000 light-years from Earth, the Magellanic Clouds are prominent features in the Southern sky. Ironically, the new discovery is not part of these galaxies, but rather is much more distant

  18. Radio planetary nebulae in the Large Magellanic Cloud

    Science.gov (United States)

    Leverenz, Howard; Filipović, Miroslav D.; Vukotić, B.; Urošević, D.; Grieve, Kevin

    2017-06-01

    We present 21 new radio-continuum detections at catalogued planetary nebula (PN) positions in the Large Magellanic Cloud (LMC) using all presently available data from the Australia Telescope Online Archive at 3, 6, 13 and 20 cm. Additionally, 11 previously detected LMC radio PNe are re-examined with seven detections confirmed and reported here. An additional three PNe from our previous surveys are also studied. The last of the 11 previous detections is now classified as a compact H II region that makes for a total sample of 31 radio PNe in the LMC. The radio-surface-brightness-to-diameter (Σ-D) relation is parametrized as Σ ∝ D-β. With the available 6 cm Σ-D data, we construct Σ-D samples from 28 LMC PNe and nine Small Magellanic Cloud (SMC) radio-detected PNe. The results of our sampled PNe in the MCs are comparable to previous measurements of the Galactic PNe. We obtain β = 2.9 ± 0.4 for the MC PNe compared to β = 3.1 ± 0.4 for the Galaxy. For a better insight into sample completeness and evolutionary features, we reconstruct the Σ-D data probability density function (PDF). The PDF analysis implies that PNe are not likely to follow linear evolutionary paths. To estimate the significance of sensitivity selection effects, we perform a Monte Carlo sensitivity simulation on the Σ-D data. The results suggest that selection effects are significant for values larger than β ˜ 2.6 and that a measured slope of β = 2.9 should correspond to a sensitivity-free value of ˜3.4.

  19. Radio-loud high-redshift protogalaxy canidates in Bootes

    Energy Technology Data Exchange (ETDEWEB)

    Croft, S; van Breugel, W; Brown, M J; de Vries, W; Dey, A; Eisenhardt, P; Jannuzi, B; Rottgering, H; Stanford, S A; Stern, D; Willner, S P

    2007-07-20

    We used the Near Infrared Camera (NIRC) on Keck I to obtain K{sub s}-band images of four candidate high-redshift radio galaxies selected using optical and radio data in the NOAO Deep Wide-Field Survey in Bootes. Our targets have 1.4 GHz radio flux densities greater than 1 mJy, but are undetected in the optical. Spectral energy distribution fitting suggests that three of these objects are at z > 3, with radio luminosities near the FR-I/FR-II break. The other has photometric redshift z{sub phot} = 1.2, but may in fact be at higher redshift. Two of the four objects exhibit diffuse morphologies in K{sub s}-band, suggesting that they are still in the process of forming.

  20. The OSIRIS-REx Radio Science Experiment at Bennu

    Science.gov (United States)

    McMahon, J. W.; Scheeres, D. J.; Hesar, S. G.; Farnocchia, D.; Chesley, S.; Lauretta, D.

    2018-02-01

    The OSIRIS-REx mission will conduct a Radio Science investigation of the asteroid Bennu with a primary goal of estimating the mass and gravity field of the asteroid. The spacecraft will conduct proximity operations around Bennu for over 1 year, during which time radiometric tracking data, optical landmark tracking images, and altimetry data will be obtained that can be used to make these estimates. Most significantly, the main Radio Science experiment will be a 9-day arc of quiescent operations in a 1-km nominally circular terminator orbit. The pristine data from this arc will allow the Radio Science team to determine the significant components of the gravity field up to the fourth spherical harmonic degree. The Radio Science team will also be responsible for estimating the surface accelerations, surface slopes, constraints on the internal density distribution of Bennu, the rotational state of Bennu to confirm YORP estimates, and the ephemeris of Bennu that incorporates a detailed model of the Yarkovsky effect.

  1. Flexible Adaptation in Cognitive Radios

    CERN Document Server

    Li, Shujun

    2013-01-01

    This book provides an introduction to software-defined radio and cognitive radio, along with methodologies for applying knowledge representation, semantic web, logic reasoning and artificial intelligence to cognitive radio, enabling autonomous adaptation and flexible signaling. Readers from the wireless communications and software-defined radio communities will use this book as a reference to extend software-defined radio to cognitive radio, using the semantic technology described. Readers with a background in semantic web and artificial intelligence will find in this book the application of semantic web and artificial intelligence technologies to wireless communications. For readers in networks and network management, this book presents a new approach to enable interoperability, collaborative optimization and flexible adaptation of network components. Provides a comprehensive ontology covering the core concepts of wireless communications using a formal language; Presents the technical realization of using a ...

  2. A robust, coupled approach for atomistic-continuum simulation.

    Energy Technology Data Exchange (ETDEWEB)

    Aubry, Sylvie; Webb, Edmund Blackburn, III (Sandia National Laboratories, Albuquerque, NM); Wagner, Gregory John; Klein, Patrick A.; Jones, Reese E.; Zimmerman, Jonathan A.; Bammann, Douglas J.; Hoyt, Jeffrey John (Sandia National Laboratories, Albuquerque, NM); Kimmer, Christopher J.

    2004-09-01

    This report is a collection of documents written by the group members of the Engineering Sciences Research Foundation (ESRF), Laboratory Directed Research and Development (LDRD) project titled 'A Robust, Coupled Approach to Atomistic-Continuum Simulation'. Presented in this document is the development of a formulation for performing quasistatic, coupled, atomistic-continuum simulation that includes cross terms in the equilibrium equations that arise due to kinematic coupling and corrections used for the calculation of system potential energy to account for continuum elements that overlap regions containing atomic bonds, evaluations of thermo-mechanical continuum quantities calculated within atomistic simulations including measures of stress, temperature and heat flux, calculation used to determine the appropriate spatial and time averaging necessary to enable these atomistically-defined expressions to have the same physical meaning as their continuum counterparts, and a formulation to quantify a continuum 'temperature field', the first step towards constructing a coupled atomistic-continuum approach capable of finite temperature and dynamic analyses.

  3. Hybrid continuum-atomistic approach to model electrokinetics in nanofluidics.

    Science.gov (United States)

    Amani, Ehsan; Movahed, Saeid

    2016-06-07

    In this study, for the first time, a hybrid continuum-atomistic based model is proposed for electrokinetics, electroosmosis and electrophoresis, through nanochannels. Although continuum based methods are accurate enough to model fluid flow and electric potential in nanofluidics (in dimensions larger than 4 nm), ionic concentration is too low in nanochannels for the continuum assumption to be valid. On the other hand, the non-continuum based approaches are too time-consuming and therefore is limited to simple geometries, in practice. Here, to propose an efficient hybrid continuum-atomistic method of modelling the electrokinetics in nanochannels; the fluid flow and electric potential are computed based on continuum hypothesis coupled with an atomistic Lagrangian approach for the ionic transport. The results of the model are compared to and validated by the results of the molecular dynamics technique for a couple of case studies. Then, the influences of bulk ionic concentration, external electric field, size of nanochannel, and surface electric charge on the electrokinetic flow and ionic mass transfer are investigated, carefully. The hybrid continuum-atomistic method is a promising approach to model more complicated geometries and investigate more details of the electrokinetics in nanofluidics. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Equivalent-Continuum Modeling With Application to Carbon Nanotubes

    Science.gov (United States)

    Odegard, Gregory M.; Gates, Thomas S.; Nicholson, Lee M.; Wise, Kristopher E.

    2002-01-01

    A method has been proposed for developing structure-property relationships of nano-structured materials. This method serves as a link between computational chemistry and solid mechanics by substituting discrete molecular structures with equivalent-continuum models. It has been shown that this substitution may be accomplished by equating the vibrational potential energy of a nano-structured material with the strain energy of representative truss and continuum models. As important examples with direct application to the development and characterization of single-walled carbon nanotubes and the design of nanotube-based devices, the modeling technique has been applied to determine the effective-continuum geometry and bending rigidity of a graphene sheet. A representative volume element of the chemical structure of graphene has been substituted with equivalent-truss and equivalent continuum models. As a result, an effective thickness of the continuum model has been determined. This effective thickness has been shown to be significantly larger than the interatomic spacing of graphite. The effective thickness has been shown to be significantly larger than the inter-planar spacing of graphite. The effective bending rigidity of the equivalent-continuum model of a graphene sheet was determined by equating the vibrational potential energy of the molecular model of a graphene sheet subjected to cylindrical bending with the strain energy of an equivalent continuum plate subjected to cylindrical bending.

  5. European Union News Themes in Romanian Radio Stations. Case Study: Europa FM and Radio Romania Actualitati

    Directory of Open Access Journals (Sweden)

    Antonia-Ioana Matei

    2013-05-01

    Full Text Available With Romania’s integration in the European Union, the media content related to the member states has acquired growing importance. The themes of journalism were enriched with new approaches towards national image in the European context and vice versa. At a first level, the study aims to conduct a quantitative analysis on the news topics broadcasted by Radio Romania Actualitati and Europa FM, for the duration of 32 days. The qualitative component focuses on the topics addressed in radio news in order to see what is the media content which reflects the image of the European Union. The findings show, beyond the numbers, that the editorial policy of the Romanian media is not concerned with the interests of the citizens - from the perspective of common themes - but rather with how can the EU, as a unified body, help member countries solve their problems.

  6. Multigrid treatment of implicit continuum diffusion

    Science.gov (United States)

    Francisquez, Manaure; Zhu, Ben; Rogers, Barrett

    2017-10-01

    Implicit treatment of diffusive terms of various differential orders common in continuum mechanics modeling, such as computational fluid dynamics, is investigated with spectral and multigrid algorithms in non-periodic 2D domains. In doubly periodic time dependent problems these terms can be efficiently and implicitly handled by spectral methods, but in non-periodic systems solved with distributed memory parallel computing and 2D domain decomposition, this efficiency is lost for large numbers of processors. We built and present here a multigrid algorithm for these types of problems which outperforms a spectral solution that employs the highly optimized FFTW library. This multigrid algorithm is not only suitable for high performance computing but may also be able to efficiently treat implicit diffusion of arbitrary order by introducing auxiliary equations of lower order. We test these solvers for fourth and sixth order diffusion with idealized harmonic test functions as well as a turbulent 2D magnetohydrodynamic simulation. It is also shown that an anisotropic operator without cross-terms can improve model accuracy and speed, and we examine the impact that the various diffusion operators have on the energy, the enstrophy, and the qualitative aspect of a simulation. This work was supported by DOE-SC-0010508. This research used resources of the National Energy Research Scientific Computing Center (NERSC).

  7. Diagnostic Reasoning across the Medical Education Continuum

    Directory of Open Access Journals (Sweden)

    C. Scott Smith

    2014-07-01

    Full Text Available We aimed to study linguistic and non-linguistic elements of diagnostic reasoning across the continuum of medical education. We performed semi-structured interviews of premedical students, first year medical students, third year medical students, second year internal medicine residents, and experienced faculty (ten each as they diagnosed three common causes of dyspnea. A second observer recorded emotional tone. All interviews were digitally recorded and blinded transcripts were created. Propositional analysis and concept mapping were performed. Grounded theory was used to identify salient categories and transcripts were scored with these categories. Transcripts were then unblinded. Systematic differences in propositional structure, number of concept connections, distribution of grounded theory categories, episodic and semantic memories, and emotional tone were identified. Summary concept maps were created and grounded theory concepts were explored for each learning level. We identified three major findings: (1 The “apprentice effect” in novices (high stress and low narrative competence; (2 logistic concept growth in intermediates; and (3 a cognitive state transition (between analytical and intuitive approaches in experts. These findings warrant further study and comparison.

  8. Software defined radio architectures evaluation

    OpenAIRE

    Palomo, Alvaro; Villing, Rudi; Farrell, Ronan

    2008-01-01

    This paper presents an performance evaluation of GNU Radio and OSSIE, two open source Software Defined Radio (SDR) architectures. The two architectures were compared by running implementations of a BPSK waveform utilising a software loopback channel on each. The upper bound full duplex throughput was found to be around 700kbps in both cases, though OSSIE was slightly faster than GNU Radio. CPU and memory loads did not differ significantly.

  9. Uzaybimer Radio Telescope Control System

    Science.gov (United States)

    Balbay, R.; Öz, G. K.; Arslan, Ö.; Özeren, F. F.; Küçük, İ.

    2016-12-01

    A 13 meters former NATO radar is being converted into a radio telescope. The radio telescope is controlled by a system which has been developed at UZAYBİMER. The Telescope Control System(TCS) has been designed using modern industrial systems. TCS has been developed in LabView platform in which works Windows embedded OS. The position feedback used on radio telescopes is an industrial EtherCAT standard. ASCOM library is used for astronomical calculations.

  10. Peculiarity of continuum emission from upper corona of the sun at decameter wavelengths

    Science.gov (United States)

    Brazhenko, A. I.; Koval, A. A.; Konovalenko, O. O.; Stanislavsky, A. A.; Abranin, E. P.; Dorovskyy, V. V.; Melnik, V. M.; Vashchishin, R. V.; Frantsuzenko, A. V.; Borysyuk, O. V.

    2012-03-01

    The results of investigations of the quiet Sun radio emission at decameter wavelengths are suggested. The observations have been made with the URAN-2 antenna array in summer seasons of 2008-2009 at 20 and 25 MHz within 250 kHz bandwidth together with the UTR-2 radio telescope in the summerautumn period of 2010 at 16.5 to 33.0 MHz in the mode of onedimensional heliograph. The average values of flux density of the quiet Sun corona according to URAN-2 measurements is equal to 860 Jy at 25 MHz and 710 Jy at 20 MHz. The values of integral flux density from UTR-2 measurements for these frequencies are 950 and 800 Jy, respectively. The URAN-2 and UTR-2 measured data as respects the spectral index within 16.5 ÷ 200 MHz have shown it to be the same and equal to -2.1±0.1. The angular sizes of equatorial diameter of solar corona have been determined from the UTR-2 observations. The results yielded are in good agreement with the values known for the continuum radiation from the solar corona at higher frequencies. The efficiency of simultaneous application of different geographically spaced radiotelescopes with coincident frequency range is shown, too.

  11. Participation in radio programmes and immigration. The Romanian case

    Directory of Open Access Journals (Sweden)

    Patricia González Aldea, Ph. D.

    2010-01-01

    Full Text Available The Spanish social reality has evolved during the last years into a multicultural society, but these “new citizens” are very poorly represented on the media. They rarely become protagonists of any piece of news and when they do, the limitations of informative programming promote an stereotyped discourse.Romanians lead the ranking of immigration by country of origin in Spain and their ethnic media are numerous. Along with these, other multicultural media give voice to the immigrants and deal more deeply with the different identities to promote integration and coexistence.Based on the hypothesis that the participation of the Romanians in radio programmes is scarce, as well as contents referring to this ethnic group, the aim of this research is to undertake a longitudinal analysis of radio consumption, the form of participation of Romanians in radio programming, and the Romanian image transmitted by these contents. Four radio programmes are analyzed: ‘Nuevos Ciudadanos’ (‘New Citizens’ from Punto Radio; ‘Otros Acentos’ (‘Other Accents’ from RNE Radio Exterior; ‘Rumano en el Mundo’ (Romanian in the World from Radio Tentación; and ‘Buenas Tardes Rumania’ (Good Afternoon Romania from Integración Radio.In the discussion and conclusion section we highlight the low consumption of radio news and two predominant forms of participation: the legal queries and musical dedications, particularly on ethnic stations, which in this way reinforce their identitary character. Furthermore, with the end of the labour moratorium for Romanians and Bulgarians since January 2009 and the free movement of these workers, the presence of this community on the programming mentioned above has decreased.

  12. Pluralismo, radio e Internet

    Directory of Open Access Journals (Sweden)

    Bruce Girard

    2015-01-01

    Full Text Available En muchas ocasiones de ha oído hablar que internet y las nuevas tecnologías de la comunicación llevarán a la humanidad a un mundo homogeneizado en donde todos compartirán la misa cultura del “ciberespacio” y hablarán el mismo lenguaje. Nuevas iniciativas en América Latina combinan la tecnología de punta y la radio para poner fin a este mito y contribuir a una comunicación más democrática.

  13. Radio Frequency Anechoic Chamber Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Supports the design, manufacture, and test of antenna systems. The facility is also used as an electromagnetic compatibility/radio frequency interference...

  14. Radio-induced brain lesions

    Directory of Open Access Journals (Sweden)

    Gorgan Mircea Radu

    2014-03-01

    Full Text Available Introduction : Radiotherapy, an important tool in multimodal oncologic treatment, can cause radio-induced brain lesion development after a long period of time following irradiation.

  15. The LOFAR window on star-forming galaxies and AGNs - curved radio SEDs and IR-radio correlation at 0

    Science.gov (United States)

    Calistro Rivera, G.; Williams, W. L.; Hardcastle, M. J.; Duncan, K.; Röttgering, H. J. A.; Best, P. N.; Brüggen, M.; Chyży, K. T.; Conselice, C. J.; de Gasperin, F.; Engels, D.; Gürkan, G.; Intema, H. T.; Jarvis, M. J.; Mahony, E. K.; Miley, G. K.; Morabito, L. K.; Prandoni, I.; Sabater, J.; Smith, D. J. B.; Tasse, C.; van der Werf, P. P.; White, G. J.

    2017-08-01

    We present a study of the low-frequency radio properties of star-forming (SF) galaxies and active galactic nuclei (AGNs) up to redshift z = 2.5. The new spectral window probed by the Low Frequency Array (LOFAR) allows us to reconstruct the radio continuum emission from 150 MHz to 1.4 GHz to an unprecedented depth for a radio-selected sample of 1542 galaxies in ∼ 7 deg2 of the LOFAR Boötes field. Using the extensive multiwavelength data set available in Boötes and detailed modelling of the far-infrared to ultraviolet spectral energy distribution (SED), we are able to separate the star formation (N = 758) and the AGN (N = 784) dominated populations. We study the shape of the radio SEDs and their evolution across cosmic time and find significant differences in the spectral curvature between the SF galaxy and AGN populations. While the radio spectra of SF galaxies exhibit a weak but statistically significant flattening, AGN SEDs show a clear trend to become steeper towards lower frequencies. No evolution of the spectral curvature as a function of redshift is found for SF galaxies or AGNs. We investigate the redshift evolution of the infrared-radio correlation for SF galaxies and find that the ratio of total infrared to 1.4-GHz radio luminosities decreases with increasing redshift: q1.4 GHz = (2.45 ± 0.04) (1 + z)-0.15 ± 0.03. Similarly, q150 MHz shows a redshift evolution following q150 GHz = (1.72 ± 0.04) (1 + z)-0.22 ± 0.05. Calibration of the 150 MHz radio luminosity as a star formation rate tracer suggests that a single power-law extrapolation from q1.4 GHz is not an accurate approximation at all redshifts.

  16. Elementary Continuum Mechanics for Everyone - And Some More

    DEFF Research Database (Denmark)

    Byskov, Esben

    Quite trivially, Continuum mechanics per se deals with the description of deformations of three-dimensional continua i.e. models whose properties are independent of scale in that the continuum does not possess a structure. Thus, continuum mechanics does not try to model the atomic structure...... of the involved materials- perhaps not even the crystalline or spongy, or lumpy structure- but offers a "smeared-out" version of the real world. Also, the desired description depends very much on the needs of the dicipline in question....

  17. Elementary Continuum Mechanics for Everyone - and Some More

    DEFF Research Database (Denmark)

    Byskov, Esben

    Quite trivially, Continuum mechanics per se deals with the description of deformations of three-dimensional continua i.e. models whose properties are independent of scale in that the continuum does not possess a structure. Thus, continuum mechanics does not try to model the atomic structure...... of the involved materials- perhaps not even the crystalline or spongy, or lumpy structure- but offers a "smeared-out" version of the real world. Also, the desired description depends very much on the needs of the discipline in question....

  18. Continuum simulations of water flow past fullerene molecules

    DEFF Research Database (Denmark)

    Popadic, A.; Praprotnik, M.; Koumoutsakos, P.

    2015-01-01

    We present continuum simulations of water flow past fullerene molecules. The governing Navier-Stokes equations are complemented with the Navier slip boundary condition with a slip length that is extracted from related molecular dynamics simulations. We find that several quantities of interest...... as computed by the present model are in good agreement with results from atomistic and atomistic-continuum simulations at a fraction of the cost. We simulate the flow past a single fullerene and an array of fullerenes and demonstrate that such nanoscale flows can be computed efficiently by continuum flow...

  19. SEACAS Theory Manuals: Part II. Nonlinear Continuum Mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Attaway, S.W.; Laursen, T.A.; Zadoks, R.I.

    1998-09-01

    This report summarizes the key continuum mechanics concepts required for the systematic prescription and numerical solution of finite deformation solid mechanics problems. Topics surveyed include measures of deformation appropriate for media undergoing large deformations, stress measures appropriate for such problems, balance laws and their role in nonlinear continuum mechanics, the role of frame indifference in description of large deformation response, and the extension of these theories to encompass two dimensional idealizations, structural idealizations, and rigid body behavior. There are three companion reports that describe the problem formulation, constitutive modeling, and finite element technology for nonlinear continuum mechanics systems.

  20. Radio Wavelength Studies of the Galactic Center Source N3, Spectroscopic Instrumentation For Robotic Telescope Systems, and Developing Active Learning Activities for Astronomy Laboratory Courses

    Science.gov (United States)

    Ludovici, Dominic Alesio

    2017-08-01

    The mysterious radio source N3 appears to be located within the vicinity of the Radio Arc region of the Galactic Center. To investigate the nature of this source, we have conducted radio observations with the VLA and the VLBA. Continuum observations between 2 and 50 GHz reveal that N3 is an extremely compact and bright source with a non-thermal spectrum. Molecular line observations with the VLA reveal a compact molecular cloud adjacent to N3 in projection. The properties of this cloud are consistent with other galactic center clouds. We are able to rule out several hypotheses for the nature of N3, though a micro-blazar origin cannot be ruled out. Robotic Telescope systems are now seeing widespread deployment as both teaching and research instruments. While these systems have traditionally been able to produce high quality images, these systems have lacked the capability to conduct spectroscopic observations. To enable spectroscopic observations on the Iowa Robotic Observatory, we have developed a low cost (˜ 500), low resolution (R ˜ 300) spectrometer which mounts inside a modified filter wheel and a moderate cost (˜ 5000), medium resolution (R ˜ 8000) fiber-fed spectrometer. Software has been developed to operate both instruments robotically and calibration pipelines are being developed to automate calibration of the data. The University of Iowa offers several introductory astronomy laboratory courses taken by many hundreds of students each semester. To improve student learning in these laboratory courses, we have worked to integrate active learning into laboratory activities. We present the pedagogical approaches used to develop and update the laboratory activities and present an inventory of the current laboratory exercises. Using the inventory, we make observations of the strengths and weaknesses of the current exercises and provide suggestions for future refinement of the astronomy laboratory curriculum.

  1. Deep GMRT 150-MHz observations of the LBDS-Lynx region: ultrasteep spectrum radio sources

    Science.gov (United States)

    Ishwara-Chandra, C. H.; Sirothia, S. K.; Wadadekar, Y.; Pal, S.; Windhorst, R.

    2010-06-01

    It has been known for nearly three decades that high-redshift radio galaxies exhibit steep radio spectra, and hence ultrasteep spectrum radio sources provide candidates for high-redshift radio galaxies. Nearly all radio galaxies with z > 3 have been found using this redshift-spectral index correlation. We have started a programme with the Giant Metrewave Radio Telescope (GMRT) to exploit this correlation at flux density levels about 10 to 100 times deeper than the known high-redshift radio galaxies which were identified primarily using the already available radio catalogues. In our programme, we have obtained deep, high-resolution radio observations at 150 MHz with GMRT for several `deep' fields which are well studied at higher radio frequencies and in other bands of the electromagnetic spectrum, with an aim to detect candidate high-redshift radio galaxies. In this paper we present results from the deep 150-MHz observations of the LBDS-Lynx field, which has been already imaged at 327, 610 and 1412 MHz with the Westerbork Synthesis Radio Telescope and at 1400 and 4860 MHz with the Very Large Array. The 150-MHz image made with GMRT has an rms noise of ˜0.7 mJy beam-1 and a resolution of ˜19 × 15 arcsec2. It is the deepest low-frequency image of the LBDS-Lynx field. The source catalogue of this field at 150 MHz has about 765 sources down to ˜20 per cent of the primary beam response, covering an area of about 15 deg2. Spectral index was estimated by cross-correlating each source detected at 150 MHz with the available observations at 327, 610, 1400 and 4860 MHz and also using available radio surveys such as the Westerbork Northern Sky Survey at 327 MHz and the NRAO VLA Sky Survey and Faint Images of the Radio Sky at Twenty-cm at 1400 MHz. We find about 150 radio sources with spectra steeper than 1. About two-third of these are not detected in the Sloan Digital Sky Survey, hence are strong candidate high-redshift radio galaxies, which need to be further explored with

  2. Radio Jove: Citizen Science for Jupiter Radio Astronomy

    Science.gov (United States)

    Higgins, C. A.; Thieman, J.; Reyes, F. J.; Typinski, D.; Flagg, R. F.; Greenman, W.; Brown, J.; Ashcraft, T.; Sky, J.; Cecconi, B.; Garcia, L. N.

    2016-12-01

    The Radio Jove Project (http://radiojove.gsfc.nasa.gov) has been operating as an educational activity for 18 years to introduce radio astronomy activities to students, teachers, and the general public. Participants may build a simple radio telescope kit, make scientific observations, and interact with radio observatories in real-time over the Internet. Recently some of our dedicated citizen science observers have upgraded their systems to better study radio emission from Jupiter and the Sun by adding dual-polarization spectrographs and wide-band antennas in the frequency range of 15-30 MHz. Some of these observations are being used in conjunction with professional telescopes such as the Long Wavelength Array (LWA), the Nancay Decametric Array, and the Ukrainian URAN2 Radio Telescope. In particular, there is an effort to support the Juno Mission radio waves instrument at Jupiter by using citizen science ground-based data for comparison and polarization verification. These data will be archived through a Virtual European Solar and Planetary Access (VESPA) archive (https://voparis-radiojove.obspm.fr/radiojove/welcome) for use by the amateur and professional radio science community. We overview the program and display recent observations that will be of interest to the science community.

  3. The coexistence of cognitive radio and radio astronomy

    NARCIS (Netherlands)

    Bentum, Marinus Jan; Boonstra, A.J.; Baan, W.A.

    2009-01-01

    An increase of the efficiency of spectrum usage requires the development of new communication techniques. Cognitive radio may be one of those new technique, which uses unoccupied frequency bands for communications. This will lead to more power in the bands and therefore an increasing level of Radio

  4. Evaluation of GNU Radio Platform Enhanced for Hardware Accelerated Radio Design

    OpenAIRE

    Karve, Mrudula Prabhakar

    2010-01-01

    The advent of software radio technology has enabled radio developers to design and imple- ment radios with great ease and flexibility. Software radios are effective in experimentation and development of radio designs. However, they have limitations when it comes to high- speed, high-throughput designs. This limitation can be overcome by introducing a hardware element to the software radio platform. Enhancing GNU Radio for Hardware Accelerated Radio Design project implements suc...

  5. Functional MR Imaging: New tool to predict outcome for cervical carcinoma of uterus treated by concomitant radio chemotherapy?; IRM fonctionnelle: nouvel outil pour predire la reponse des cancers du col uterin a la chimioradiotherapie concomitante?

    Energy Technology Data Exchange (ETDEWEB)

    Taieb, S.; Faivre-Pierret, M.; Ceugnart, L. [Centre Oscar-Lambret, Dept. d' Imagerie, 59 - Lille (France); Nickers, P. [Centre Oscar-Lambret, Dept. de Radiotherapie, 59 - Lille (France); Lesoin, A.; Narducci, F. [Centre Oscar-Lambret, Dept. de Gynecologie Oncologique, 59 - Lille (France)

    2009-10-15

    The treatment of advanced cervix is concomitant radio chemotherapy. Local prognosis and global survival depend on tumoral volume, locoregional extension and radio sensitivity of the lesion. This one is function of tumoral hypoxia, tumoral interstitial pressure and existence of an anaemia. Dynamic contract enhanced MRI (D.C.E.-MRI) allows to quantify pilot vascular parameters of the first two factors. Combined analysis: tumoral volume, anaemia and vascular parameters before and in the course of treatment allows a strong correlation with the risk of local recurrence and global survival. (authors)

  6. Dramatugi Penyiar Radio

    Directory of Open Access Journals (Sweden)

    Hastika Yanti Nora

    2009-07-01

    Full Text Available Dramaturgy is the work of Erving Goffman. He wrote "Presentation of Self in Everyday Life" in '1959. Following the theatrical analogy, Goffman spoke of a front stage and back stage. The front stage is that part of the performance that generally functions in rather fixed and general ways to define the situation for those who observed the performance. The back stage is situation where facts suppressed in the front or various kinds of informal actions may appear. A back stage is usually adjacent to the front stage, but it also cut off from it. Everyone in this world have to run his role in their everyday life. It also a radio announcer. As an actor, they have to be a nice and friendy person when they perform to make air personality, that is  a good  impression, from their audience. But before their perform in the front stage, there so much to do to prepare in the backstage. The front and back stage is radio announcer dramaturgy.

  7. Microstructural and continuum evolution modeling of sintering.

    Energy Technology Data Exchange (ETDEWEB)

    Braginsky, Michael V.; Olevsky, Eugene A. (San Diego State University, San Diego, CA); Johnson, D. Lynn (Northwest University, Evanston, IL); Tikare, Veena; Garino, Terry J.; Arguello, Jose Guadalupe, Jr.

    2003-12-01

    All ceramics and powder metals, including the ceramics components that Sandia uses in critical weapons components such as PZT voltage bars and current stacks, multi-layer ceramic MET's, ahmindmolybdenum & alumina cermets, and ZnO varistors, are manufactured by sintering. Sintering is a critical, possibly the most important, processing step during manufacturing of ceramics. The microstructural evolution, the macroscopic shrinkage, and shape distortions during sintering will control the engineering performance of the resulting ceramic component. Yet, modeling and prediction of sintering behavior is in its infancy, lagging far behind the other manufacturing models, such as powder synthesis and powder compaction models, and behind models that predict engineering properties and reliability. In this project, we developed a model that was capable of simulating microstructural evolution during sintering, providing constitutive equations for macroscale simulation of shrinkage and distortion during sintering. And we developed macroscale sintering simulation capability in JAS3D. The mesoscale model can simulate microstructural evolution in a complex powder compact of hundreds or even thousands of particles of arbitrary shape and size by 1. curvature-driven grain growth, 2. pore migration and coalescence by surface diffusion, 3. vacancy formation, grain boundary diffusion and annihilation. This model was validated by comparing predictions of the simulation to analytical predictions for simple geometries. The model was then used to simulate sintering in complex powder compacts. Sintering stress and materials viscous module were obtained from the simulations. These constitutive equations were then used by macroscopic simulations for simulating shrinkage and shape changes in FEM simulations. The continuum theory of sintering embodied in the constitutive description of Skorohod and Olevsky was combined with results from microstructure evolution simulations to model shrinkage

  8. Weak and Compact Radio Emission in Early High-Mass Star Forming Regions

    Science.gov (United States)

    Rosero Rueda, Viviana Andrea

    2017-04-01

    I present a high sensitivity radio continuum survey at 6 and 1.3 cm using the Karl. G. Jansky Very Large Array towards a sample of 58 high-mass star forming regions. The sample was chosen from clumps within infrared dark clouds, also known as cold molecular clumps (CMCs) with and without IR sources (CMC-IRs, CMCs, respectively) and hot molecular cores (HMCs), with no previous radio continuum detection at the 1 mJy level. Due to the remarkable improvement in the continuum sensitivity of the VLA, this survey achieved map rms levels of 3-10 ?Jy/beam at sub-arcsecond angular resolution. From this dataset I extracted 70 centimeter continuum sources that are associated with 1.2 mm dust clumps. Most sources are weak, compact, and are prime candidates for high-mass protostars. Detection rates of radio sources associated with the mm dust clumps for CMCs, CMC-IRs and HMCs are 6%, 53% and 100%, respectively. This result is consistent with increasing high-mass star formation activity from CMCs to HMCs. I calculated 5-25 GHz spectral indices using power law fits and obtain a median value of 0.5 (i.e., flux increasing with frequency), which is consistent with thermal emission from ionized jets. Moreover, these detected ionized jets towards high-mass stars are well correlated with jets formed towards lower masses, providing further evidence that ionized jets from any luminosity have a common origin. Ultimately, this set of detections will likely provide good candidates to enable new tests of high-mass star formation theories, in particular testing predictions of core accretion and competitive accretion models.

  9. The Hurricane-Flood-Landslide Continuum

    Science.gov (United States)

    Negri, Andrew J.; Burkardt, Nina; Golden, Joseph H.; Halverson, Jeffrey B.; Huffman, George J.; Larsen, Matthew C.; McGinley, John A.; Updike, Randall G.; Verdin, James P.; Wieczorek, Gerald F.

    2005-01-01

    In August 2004, representatives from NOAA, NASA, the USGS, and other government agencies convened in San Juan, Puerto Rim for a workshop to discuss a proposed research project called the Hurricane-Flood-Landslide Continuum (HFLC). The essence of the HFLC is to develop and integrate tools across disciplines to enable the issuance of regional guidance products for floods and landslides associated with major tropical rain systems, with sufficient lead time that local emergency managers can protect vulnerable populations and infrastructure. All three lead agencies are independently developing precipitation-flood-debris flow forecasting technologies, and all have a history of work on natural hazards both domestically and overseas. NOM has the capability to provide tracking and prediction of storm rainfall, trajectory and landfall and is developing flood probability and magnTtude capabilities. The USGS has the capability to evaluate the ambient stability of natural and man-made landforms, to assess landslide susceptibilities for those landforms, and to establish probabilities for initiation of landslides and debris flows. Additionally, the USGS has well-developed operational capacity for real-time monitoring and reporting of streamflow across distributed networks of automated gaging stations (http://water.usgs.gov/waterwatch/). NASA has the capability to provide sophisticated algorithms for satellite remote sensing of precipitation, land use, and in the future, soil moisture. The Workshop sought to initiate discussion among three agencies regarding their specific and highly complimentary capabilities. The fundamental goal of the Workshop was to establish a framework that will leverage the strengths of each agency. Once a prototype system is developed for example, in relatively data-rich Puerto Rim, it could be adapted for use in data-poor, low-infrastructure regions such as the Dominican Republic or Haiti. This paper provides an overview of the Workshop s goals

  10. Continuum definition for Ceres absorption bands at 3.1, 3.4 and 4.0 μm

    Science.gov (United States)

    Galiano, A.; Palomba, E.; Longobardo, A.; Zinzi, A.; De Sanctis, M. C.; Raponi, A.; Carrozzo, F. G.; Ciarniello, M.; Dirri, F.

    2017-09-01

    The images and hyperspectral data acquired during various Dawn mission phases (e.g. Survey, HAMO and LAMO) allowed identifying regions of different albedo on Ceres surface, where absorption bands located at 3.4 and 4.0 μm can assume different shapes. The 3.1 μm feature is observed on the entire Ceres surface except on Cerealia Facula, the brightest spot located on the dome of Occator crater. To perform a mineralogical investigation, absorption bands in reflectance spectra should be properly isolated by removing spectral continuum; hence, parameters as band centers and band depths must be estimated. The problem in the defining the continuum is in the VIR spectral range, which ends at 5.1 μm even though the reliable data, where the thermal contribution is properly removed, stops at 4.2 μm. Band shoulders located at longer wavelengths cannot be estimated. We defined different continua, with the aim to find the most appropriate to isolate the three spectral bands, whatever the region and the spatial resolution of hyperspectral images. The linear continuum seems to be the most suitable definition for our goals. Then, we performed an error evaluation on band depths and band centers introduced by this continuum definition.

  11. EFFICIENT COMPUTATION OF PROLATE SPHEROIDAL WAVE FUNCTIONS IN RADIO ASTRONOMICAL SOURCE MODELING

    NARCIS (Netherlands)

    Noorishad, Parisa; Yatawatta, Sarod

    2011-01-01

    The application of orthonormal basis functions such as Prolate Spheroidal Wave Functions (PSWF) for accurate source modeling in radio astronomy has been comprehensively studied. They are of great importance for high fidelity, high dynamic range imaging with new radio telescopes as well as

  12. A Hidden Radio Halo in the Galaxy Cluster A 1682? T. Venturi1 ...

    Indian Academy of Sciences (India)

    Beyond those individual sources, residuals are present in the central cluster region, suggestive of a radio halo outshined by the bright individual radio sources. We carried out follow-up observations of A1682 over a wide frequency range, in order to study the spectral properties of the individual sources, and possibly image.

  13. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... Resources Professions Site Index A-Z Children’s (Pediatric) Magnetic Resonance Imaging Children’s magnetic resonance imaging (MRI) uses a powerful magnetic field, radio waves ...

  14. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... News Physician Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) - Head Magnetic resonance imaging (MRI) of the head uses a powerful magnetic field, radio waves and a computer to produce ...

  15. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... Resources Professions Site Index A-Z Children’s (Pediatric) Magnetic Resonance Imaging Children’s magnetic resonance imaging (MRI) uses a powerful magnetic field, radio ...

  16. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... being imaged, send and receive radio waves, producing signals that are detected by the coils. The electric ... with the patient. A computer then processes the signals and generates a series of images, each of ...

  17. The Dependence of the IR-Radio Correlation on the Metallicity

    Science.gov (United States)

    Qiu, Jianjie; Shi, Yong; Wang, Junzhi; Zhang, Zhi-Yu; Zhou, Luwenjia

    2017-09-01

    We have compiled a sample of 26 metal-poor galaxies with 12 + log(O/H) infrared continuum and 1.4 GHz radio continuum data. By comparing to galaxies at higher metallicity, we have investigated the IR-radio relationship’s dependence on metallicity at the 24, 70, 100, and 160 μm bands, as well as the integrated FIR luminosity. It is found that metal-poor galaxies have on average lower {q}{IR} than metal-rich ones, with larger offsets at longer IR wavelengths, from -0.06 dex in {q}24μ {{m}} to -0.6 dex in {q}160μ {{m}}. The {q}{IR} of all galaxies as a whole at 160 μm show positive trends with the metallicity and IR-to-FUV ratio and negative trends with the IR color, while those at lower IR wavelengths show weaker correlations. We propose a mechanism that invokes the combined effects of low obscured-SFR-to-total-SFR fraction and warm dust temperature at low metallicity to interpret the above behavior of {q}{IR}, with the former reducing the IR radiation and the latter further reducing the IR emission at longer IR wavelengths. Other mechanisms that are related to the radio emission, including the enhanced magnetic field strength and increased thermal radio contribution, are unable to reconcile the IR-wavelength-dependent differences of {q}{IR} between metal-poor and metal-rich galaxies. In contrast to {q}{IR}, the mean total-SFR-to-radio ratio of metal-poor galaxies is the same as that for metal-rich galaxies, indicating the 1.4 GHz radio emission is still an effective tracer of SFRs at low metallicity.

  18. Evaluation the Effectiveness of the US Navy Leadership Continuum Curricula

    National Research Council Canada - National Science Library

    Duncan-White, Delores

    1997-01-01

    .... A Leadership Continuum Survey Questionnaire was developed to identified and analyze the student's attitudes concerning the effectiveness of the knowledge and skills taught in the course and how these...

  19. Equivalent-Continuum Modeling of Nano-Structured Materials

    Science.gov (United States)

    Odegard, Gregory M.; Gates, Thomas S.; Nicholson, Lee M.; Wise, Kristopher E.

    2001-01-01

    A method has been developed for modeling structure-property relationships of nano-structured materials. This method serves as a link between computational chemistry and solid mechanics by substituting discrete molecular structures with an equivalent-continuum model. It has been shown that this substitution may be accomplished by equating the vibrational potential energy of a nano-structured material with the strain energy of representative truss and continuum models. As an important example with direct application to the development and characterization of single-walled carbon nanotubes, the model has been applied to determine the effective continuum geometry of a graphene sheet. A representative volume element of the equivalent-continuum model has been developed with an effective thickness. This effective thickness has been shown to be similar to, but slightly smaller than, the interatomic spacing of graphite.

  20. Asymmetric continuum extreme processes in solids and fluids

    CERN Document Server

    Teisseyre, Roman

    2014-01-01

    This book deals with a class of basic deformations in asymmetric continuum theory. It describes molecular deformations and transport velocities in fluids, strain deformations in solids as well as the molecular transport, important in fracture processes.

  1. IUTAM-Symposium on The Generalized Cosserat Continuum and the Continuum Theory of Dislocations with Applications

    CERN Document Server

    1968-01-01

    5 The symposium was held in Freudenstadt from 28\\h to 31 \\ ofAugust st nd 1967 and in Stuttgart from 1 to 2 of September 1967. The proposal to hold this symposium originated with the German Society of Applied Mathematics and Mechanics (GAMM) late in 1964 and was examined by a committee of IUTAM especially appointed for this purpose. The basis of this examination was a report in which the present situation in the field and the possible aims of the symposium were surveyed. Briefly, the aims of the symposium were stated to be 1. the unification of the various approaches developed in recent years with the aim of penetrating into the microscopic world of matter by means of continuum theories; 2. the bridging of the gap between microscopic (or atomic) research on mechanics on one hand, and the phenomenological (or continuum mechanical) approach on the other hand; 3. the physical interpretation and the relation to actual material behaviour of the quantities and laws introduced into the new theories, together with ap...

  2. rtpipe: Searching for Fast Radio Transients in Interferometric Data

    Science.gov (United States)

    Law, Casey J.

    2017-06-01

    rtpipe (real-time pipeline) analyzes radio interferometric data with an emphasis on searching for transient or variable astrophysical sources. The package combines single-dish concepts such as dedispersion and filters with interferometric concepts, including images and the uv-plane. In contrast to time-domain data recorded with large single-dish telescopes, visibilities from interferometers can precisely localize sources anywhere in the entire field of view. rtpipe opens interferometers to the study of fast transient sky, including sources like pulsars, stellar flares, rotating radio transients, and fast radio bursts. Key portions of the search pipeline, such as image generation and dedispersion, have been accelerated. That, in combination with its multi-threaded, multi-node design, makes rtpipe capable of searching millisecond timescale data in real time on small compute clusters.

  3. Bursts and shocks in a continuum shell model

    DEFF Research Database (Denmark)

    Andersen, Ken Haste; Bohr, Tomas; Jensen, M.H.

    1998-01-01

    We study a burst event, i.e., the evolution of an initial condition having support only in a finite interval of k-space, in the continuum shell model due to Parisi. We show that the continuum equation without forcing or dissipation can be explicitly written in characteristic form and that the right...... and left moving parts can be solved exactly. When this is supplemented by the approximate shock condition it is possible to find the symptotic form of the burst....

  4. Progress in Using Continuum radiation for AXAF Calibration

    Science.gov (United States)

    Kolodziejczak, J. J.; Austin, R. A.; Elsner, R. F.; O'Dell, S. L.; Sulkanen, M. E.; Swartz, D. A.; Tennant, A. F.; Weisskopf, M. C.; Zirnstein, G.; McDermott, W. C.; hide

    1998-01-01

    X-ray calibration of the AXAF observatory at MSFC's X-Ray Calibration Facility (XRCF) made novel use of the x-ray continuum from a conventional electron-impact source. Taking advantage of the good spectral resolution of solid-state detectors, continuum measurements proved advantageous in calibrating the effective area of AXAF's High-Resolution Mirror Assembly (HRMA) and in verifying its alignment to the XRCF's optical axis. Further verification of AXAF response models will be presented.

  5. Uses of continuum radiation in the AXAF calibration

    Science.gov (United States)

    Kolodziejczak, J. J.; Austin, R. A.; Elsner, R. F.; O'Dell, S. L.; Sulkanen, M. E.; Swartz, D. A.; Tennant, A. F.; Weisskopf, M. C.; Zirnstein, G.; McDermott, W. C.

    1997-01-01

    X-ray calibration of the Advanced X-ray Astrophysics Facility (AXAF) observatory at the MSFC X-Ray Calibration Facility (XRCF) made novel use of the x-ray continuum from a conventional electron-impact source. Taking advantage of the good spectral resolution of solid-state detectors, continuum measurements proved advantageous in calibrating the effective area of AXAF's High-Resolution Mirror Assembly (HRMA) and in verifying its alignment to the XRCF's optical axis.

  6. Renormalization group and continuum limit of quantum cellular automata

    Energy Technology Data Exchange (ETDEWEB)

    Zimboras, Zoltan [Quantum Information Theory Group, ISI, Torino (Italy)

    2012-07-01

    We develop a renormalization group formalism for quantum cellular automata (reminiscent of the algebraic renormalization group of Buchholz and Verch). Using this formalism, we can define the continuum limit for certain automata. As a particular example, we show that the continuum limit of the so-called ''Glider Clifford cellular automaton'' is the 1+1 dimensional relativistic QFT of free Majorana fermions.

  7. Assessing continuum postulates in simulations of granular flow

    OpenAIRE

    Rycroft, Chris

    2009-01-01

    Continuum mechanics relies on the fundamental notion of a mesoscopic volume "element" in which properties averaged over discrete particles obey deterministic relationships. Recent work on granular materials suggests a continuum law may be inapplicable, revealing inhomogeneities at the particle level, such as force chains and slow cage breaking. Here, we analyze large-scale three-dimensional Discrete-Element Method (DEM) simulations of different granular flows and show that an approximate "gra...

  8. RADIO NOISE ADVANCES SEXUAL MATURITY

    African Journals Online (AJOL)

    ansistf-lewis

    partially illuminated by the normally non-stimulatory 7-h photoperiod, is another possible reason for the earlier sexual development. Plasma melatonin concentrations midway through the 7-h dark period in which the radio was played were similar to those of non-radio controls, indicating that this period was not regarded.

  9. Tuning in to pavement radio

    NARCIS (Netherlands)

    Ellis, S.D.K.

    1989-01-01

    This article describes a phenomenon known all over Africa, for which there is no really satisfactory term in English but which is summed up in the French term 'radio trottoir', literally 'pavement radio'. It may be defined as the popular and unofficial discussion of current affairs in Africa,

  10. Radio design in nanometer technologies

    CERN Document Server

    Ismail, Mohammed

    2006-01-01

    This is the first volume that looks at the integrated radio design problem as a "piece of a big puzzle" Most books discuss more on communications or more on hardware but not both, this book strikes the right balance between the two and provides the reader with a holistic view of the subject of radio design: current and future trends.

  11. Cognitive Radio for Emergency Networks

    NARCIS (Netherlands)

    Zhang, Q.; Kokkeler, Andre B.J.; Smit, Gerardus Johannes Maria

    2006-01-01

    In the scope of the Adaptive Ad-hoc Freeband (AAF) project, an emergency network built on top of Cognitive Radio is proposed to alleviate the spectrum shortage problem which is the major limitation for emergency networks. Cognitive Radio has been proposed as a promising technology to solve

  12. Radio and γ-Ray Variability in the BL Lac PKS 0219-164: Detection of Quasi-periodic Oscillations in the Radio Light Curve

    Science.gov (United States)

    Bhatta, Gopal

    2017-09-01

    In this work, we explore the long-term variability properties of the blazar PKS 0219-164 in the radio and the γ-ray regime, utilizing the OVRO 15 GHz and the Fermi/LAT observations from the period 2008-2017. We found that γ-ray emission is more variable than the radio emission implying that γ-ray emission possibly originated in more compact regions while the radio emission represented continuum emission from the large-scale jets. Also, in the γ-ray, the source exhibited spectral variability, characterized by the softer-when-brighter trend, a less frequently observed feature in the high-energy emission by BL Lacs. In radio, using Lomb-Scargle periodogram and weighted wavelet z-transform, we detected a strong signal of quasi-periodic oscillation (QPO) with a periodicity of 270 ± 26 days with possible harmonics of 550 ± 42 and 1150 ± 157 day periods. At a time when detections of QPOs in blazars are still under debate, the observed QPO with high statistical significance (˜97%-99% global significance over underlying red-noise processes) and persistent over nearly 10 oscillations could make one of the strongest cases for the detection of QPOs in blazar light curves. We discuss various blazar models that might lead to the γ-ray and radio variability, QPO, and the achromatic behavior seen in the high-energy emission from the source.

  13. Spitzer mid-IR spectroscopy of powerful 2Jy and 3CRR radio galaxies. II. AGN power indicators and unification

    Energy Technology Data Exchange (ETDEWEB)

    Dicken, D. [CEA-Saclay, F-91191 Gif-sur-Yvette (France); Tadhunter, C. [University of Sheffield, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Morganti, R. [ASTRON, P.O. Box 2, 7990 AA Dwingeloo (Netherlands); Axon, D.; Robinson, A.; Magagnoli, M. [Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623 (United States); Kharb, P. [Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560034 (India); Ramos Almeida, C. [Instituto de Astrofisica de Canarias (IAC), C/V ia Lactea, s/n, E-38205 La Laguna, Tenerife (Spain); Mingo, B. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Hardcastle, M. [School of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield AL10 9AB (United Kingdom); Nesvadba, N. P. H.; Singh, V. [Institut d' Astrophysique Spatiale, CNRS, Université Paris Sud, F-91405 Orsay (France); Kouwenhoven, M. B. N. [Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Haidian Qu, Beijing 100871 (China); Rose, M.; Spoon, H. [224 Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States); Inskip, K. J. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Holt, J., E-mail: daniel.dicken@cea.fr [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)

    2014-06-20

    It remains uncertain which continuum and emission line diagnostics best indicate the bolometric powers of active galactic nuclei (AGNs), especially given the attenuation caused by the circumnuclear material and the possible contamination by components related to star formation. Here we use mid-IR spectra along with multiwavelength data to investigate the merit of various diagnostics of AGN radiative power, including the mid-IR [Ne III] λ25.89 μm and [O IV] λ25.89 μm fine-structure lines, the optical [O III] λ5007 forbidden line, and mid-IR 24 μm, 5 GHz radio, and X-ray continuum emission, for complete samples of 46 2Jy radio galaxies (0.05 < z < 0.7) and 17 3CRR FRII radio galaxies (z < 0.1). We find that the mid-IR [O IV] line is the most reliable indicator of AGN power for powerful radio-loud AGNs. By assuming that the [O IV] is emitted isotropically, and comparing the [O III] and 24 μm luminosities of the broad- and narrow-line AGNs in our samples at fixed [O IV] luminosity, we show that the [O III] and 24 μm emission are both mildly attenuated in the narrow-line compared to the broad-line objects by a factor of ≈2. However, despite this attenuation, the [O III] and 24 μm luminosities are better AGN power indicators for our sample than either the 5 GHz radio or the X-ray continuum luminosities. We also detect the mid-IR 9.7 μm silicate feature in the spectra of many objects but not ubiquitously: at least 40% of the sample shows no clear evidence for these features. We conclude that, for the majority of powerful radio galaxies, the mid-IR lines are powered by AGN photoionization.

  14. Discovery of a Kiloparsec Extended Hard X-Ray Continuum and Fe-Kα from the Compton Thick AGN ESO 428-G014

    Science.gov (United States)

    Fabbiano, G.; Elvis, M.; Paggi, A.; Karovska, M.; Maksym, W. P.; Raymond, J.; Risaliti, G.; Wang, Junfeng

    2017-06-01

    We report the discovery of kiloparsec-scale diffuse emission in both the hard continuum (3-6 keV) and in the Fe-Kα line in the Compton thick (CT) Seyfert galaxy ESO 428-G014. This extended hard component contains at least ˜24% of the observed 3-8 keV emission, and follows the direction of the extended optical line emission (ionization cone) and radio jet. The extended hard component has ˜0.5% of the intrinsic 2-10 keV luminosity within the bi-cones. A uniform scattering medium of density 1 {{cm}}-3 would produce this luminosity in a 1 kpc path length in the bi-cones. Alternatively, higher column density molecular clouds in the disk of ESO 428-G014 may be responsible for these components. The continuum may also be enhanced by the acceleration of charged particles in the radio jet. The steeper spectrum (Γ ˜ 1.7 ± 0.4) of the hard continuum outside of the central 1.″5 radius nuclear region suggests a contribution of scattered/fluorescent intrinsic Seyfert emission. Ultrafast nuclear outflows cannot explain the extended Fe-Kα emission. This discovery suggests that we may need to revise the picture at the base of our interpretation of CT AGN spectra.

  15. Radio outburst of BL Lacertae

    Science.gov (United States)

    Buemi, C. S.; Leto, P.; Trigilio, C.; Umana, G.; Giroletti, M.; Orienti, M.; Raiteri, C. M.; Villata, M.; Bach, U.

    2013-04-01

    We report on extremely high radio flux of BL Lacertae at 43 and 8 GHz. Observations at 43 GHz with the 32 m radio telescope in Noto (Italy) revealed a flux density of 10.5 +/- 0.2 Jy on 2013 April 10.65, while observations at 8 GHz with the 32 m radio telescope in Medicina (Italy) detected a flux density of 8.2 +/- 0.7 Jy on April 12.22. These extremely high radio fluxes show that the radio activity likely correlated to the strong optical, near-infrared, and gamma-ray activity of 2011-2012 (see ATels #4028, #4031, #4155, #4271, #4277, #4349, #4565, #4600), and X-ray activity of late 2012 (ATels #4557, #4627), is far to be exhausted.

  16. Radio propagation measurement and channel modelling

    CERN Document Server

    Salous, Sana

    2013-01-01

    While there are numerous books describing modern wireless communication systems that contain overviews of radio propagation and radio channel modelling, there are none that contain detailed information on the design, implementation and calibration of radio channel measurement equipment, the planning of experiments and the in depth analysis of measured data. The book would begin with an explanation of the fundamentals of radio wave propagation and progress through a series of topics, including the measurement of radio channel characteristics, radio channel sounders, measurement strategies

  17. A Radio Galaxy at z = 5.19

    Science.gov (United States)

    van Breugel, Wil; De Breuck, Carlos; Stanford, S. A.; Stern, Daniel; Röttgering, Huub; Miley, George

    1999-06-01

    We report the discovery of the most distant known active galactic nucleus, the radio galaxy TN J0924-2201 at z=5.19. The radio source was selected from a new sample of ultrasteep spectrum sources, has an extreme radio spectral index α1.4GHz365MHz=-1.63, and is identified at near-IR wavelengths with a very faint, K=21.3+/-0.3 object. Spectroscopic observations show a single emission line at λ~7530 Å, which we identify as Lyα. The K-band image, sampling rest-frame U band, shows a multicomponent, radio-aligned morphology, which is typical of lower-redshift radio galaxies. TN J0924-2201 extends the near-IR Hubble, or K-z, relation for powerful radio galaxies to z>5 and is consistent with models of massive galaxies forming at even higher redshifts. Based on observations at the W. M. Keck Observatory, which is operated as a scientific partnership among the University of California, the California Institute of Technology, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  18. The Radio Language Arts Project: adapting the radio mathematics model.

    Science.gov (United States)

    Christensen, P R

    1985-01-01

    Kenya's Radio Language Arts Project, directed by the Academy for Educational Development in cooperation with the Kenya Institute of Education in 1980-85, sought to teach English to rural school children in grades 1-3 through use of an intensive, radio-based instructional system. Daily 1/2 hour lessons are broadcast throughout the school year and supported by teachers and print materials. The project further was aimed at testing the feasibility of adaptation of the successful Nicaraguan Radio Math Project to a new subject area. Difficulties were encountered in articulating a language curriculum with the precision required for a media-based instructional system. Also a challenge was defining the acceptable regional standard for pronunciation and grammar; British English was finally selected. An important modification of the Radio Math model concerned the role of the teacher. While Radio Math sought to reduce the teacher's responsibilities during the broadcast, Radio Language Arts teachers played an important instructional role during the English lesson broadcasts by providing translation and checks on work. Evaluations of the Radio language Arts Project suggest significant gains in speaking, listening, and reading skills as well as high levels of satisfaction on the part of parents and teachers.

  19. Implementing Software Defined Radio

    CERN Document Server

    Grayver, Eugene

    2013-01-01

    Software Defined Radio makes wireless communications easier, more efficient, and more reliable. This book bridges the gap between academic research and practical implementation. When beginning a project, practicing engineers, technical managers, and graduate students can save countless hours by considering the concepts presented in these pages. The author covers the myriad options and trade-offs available when selecting an appropriate hardware architecture. As demonstrated here, the choice between hardware- and software-centric architecture can mean the difference between meeting an aggressive schedule and bogging down in endless design iterations. Because of the author’s experience overseeing dozens of failed and successful developments, he is able to present many real-life examples. Some of the key concepts covered are: Choosing the right architecture for the market – laboratory, military, or commercial Hardware platforms – FPGAs, GPPs, specialized and hybrid devices Standardization efforts to ens...

  20. AGONIZAN RADIOS MINERAS

    Directory of Open Access Journals (Sweden)

    Raquel Salinas

    2015-01-01

    Full Text Available Se ofrece un amplio análisis sobre la industria electoral, recordando que un candidato a presidente es "un producto para la venta". Se Desmenuzan las estrategias utilizadas en el plebiscito chileno,las elecciones norteamericanas con el NO a BUSH. El Mercadeo Social es una nueva metodología utilizada en proyectos de desarrollo a nivel de campo por ello se hace un esclarecimiento y clarifica el vínculo con la comunicación. Se agrega temas como: Los modelos de recepción de mensajes cuyos marcos conceptuales y metodologías aún no se han adaptado al potencial de esta línea de trabajo.Se analiza la agonía de las radios mineras en Bolivia en la que 42 años de historia y heroísmo se desmoronan.

  1. Japanese radio telescopes

    Science.gov (United States)

    Kawaguchi, Noriyuki

    Japanese principal radio telescopes available for Very Long Baseline Interferometry (VLBI) observations are overviewed, and their characteristics and performances are summarized. Three fixed stations, Usuda, Nobeyama, and Kashima, and one 5-m mobile station use a hydrogen master-frequency standard, while other stations use an ultrastable X'tal oscillator locked to a cesium frequency standard. The 64-m telescope in Usuda developed for tracking satellites of deep-space missions is outlined, as well as the Kashima 34-m telescope covering a frequency range from 300 MHz to 49 GHz with 11 receivers. Attention is given to the Nobeyama 45-m telescope as a major telescope in Japan working in an international mm-VLBI network.

  2. Global Ionosphere Radio Observatory

    Science.gov (United States)

    Galkin, I. A.; Reinisch, B. W.; Huang, X. A.

    2014-12-01

    The Global Ionosphere Radio Observatory (GIRO) comprises a network of ground-based high-frequency vertical sounding sensors, ionosondes, with instrument installations in 27 countries and a central Lowell GIRO Data Center (LGDC) for data acquisition and assimilation, including 46 real-time data streams as of August 2014. The LGDC implemented a suite of technologies for post-processing, modeling, analysis, and dissemination of the acquired and derived data products, including: (1) IRI-based Real-time Assimilative Model, "IRTAM", that builds and publishes every 15-minutes an updated "global weather" map of the peak density and height in the ionosphere, as well as a map of deviations from the classic IRI climate; (2) Global Assimilative Model of Bottomside Ionosphere Timelines (GAMBIT) Database and Explorer holding 15 years worth of IRTAM computed maps at 15 minute cadence;. (3) 17+ million ionograms and matching ionogram-derived records of URSI-standard ionospheric characteristics and vertical profiles of electron density; (4) 10+ million records of the Doppler Skymaps showing spatial distributions over the GIRO locations and plasma drifts; (5) Data and software for Traveling Ionospheric Disturbance (TID) diagnostics; and (6) HR2006 ray tracing software mated to the "realistic" IRTAM ionosphere. In cooperation with the URSI Ionosonde Network Advisory Group (INAG), the LGDC promotes cooperative agreements with the ionosonde observatories of the world to accept and process real-time data of HF radio monitoring of the ionosphere, and to promote a variety of investigations that benefit from the global-scale, prompt, detailed, and accurate descriptions of the ionospheric variability.

  3. Solar polar orbit radio telescope for space weather forecast

    Science.gov (United States)

    Wu, J.; Wang, C.; Wang, S.; Wu, J.; Sun, W.; Cai, J.; Yan, Y.

    Radio emission from density plasma can be detected at low radio frequencies. An image of such plasma clouds of the entire inner interplanetary space is always a wanted input for space weather forecast and ICME propagation studies. To take such an image within the ecliptic plane may not fully explore what is happening around the Sun not only because of the blockage of the Sun, also because most of the ICMEs are propagating in the low-latitude of the Sun, near the ecliptic plane. It is then proposed to launch a solar polar orbit radio telescope to acquire high density plasma cloud images from the entire inner interplanetary space. Low radio frequency images require a large antenna aperture in space. It is, therefore, proposed to use the existing passive synthetic aperture radiometer technology to reduce mass and complicity of the deployment system of the big antenna. In order to reduce the mass of the antenna by using minimum number of elements, a zero redundant antenna element design can be used with a rotating time-shared sampling system. A preliminary assessment study shows the mission is feasible.

  4. galario: Gpu Accelerated Library for Analyzing Radio Interferometer Observations

    Science.gov (United States)

    Tazzari, Marco; Beaujean, Frederik; Testi, Leonardo

    2017-10-01

    The galario library exploits the computing power of modern graphic cards (GPUs) to accelerate the comparison of model predictions to radio interferometer observations. It speeds up the computation of the synthetic visibilities given a model image (or an axisymmetric brightness profile) and their comparison to the observations.

  5. Explosive and Radio-Selected Transients: Transient Astronomy with ...

    Indian Academy of Sciences (India)

    Therefore, multiwaveband observational efforts with wide fields of view will be the key to progress of transients astronomy from the middle 2020s offering unprecedented deep images and high spatial and spectral resolutions. Radio observations of Gamma Ray Bursts (GRBs) with SKA will uncover not only much fainter ...

  6. Radio emission of the group of stars in the Aquarius and Cetus constellations

    Directory of Open Access Journals (Sweden)

    Anton A. Lipovka

    2017-06-01

    Full Text Available In the present work, the optical identification of a group of radio sources located in the Aquarius and Cetus constellations in a field with the size of 1.2 square degrees has been carried out. Ten radio sources under investigation were identified with stars and one object was identified with a diffuse image (ESO-538-10. It should be stressed that eight radio objects were found to have a non-thermal radio spectrum. This fact is likely to indicate the presence of the significant magnetic field in the atmosphere of the sources. Precise radio and optical coordinates of the identified objects were suggested. Significant radio refraction in the interstellar medium in the tested space direction was revealed.

  7. THE RADIO AND OPTICAL LUMINOSITY EVOLUTION OF QUASARS. II. THE SDSS SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Singal, J.; Petrosian, V. [Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory and Stanford University, 382 Via Pueblo Mall, Stanford, CA 94305-4060 (United States); Stawarz, L. [Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5510 (Japan); Lawrence, A., E-mail: jsingal@stanford.edu [University of Edinburgh Institute for Astronomy, Scottish Universities Physics Alliance (SUPA), Royal Observatory, Blackford Hill, Edinburgh (United Kingdom)

    2013-02-10

    We determine the radio and optical luminosity evolutions and the true distribution of the radio-loudness parameter R, defined as the ratio of the radio to optical luminosity, for a set of more than 5000 quasars combining Sloan Digital Sky Survey optical and Faint Images of the Radio Sky at Twenty cm (FIRST) radio data. We apply the method of Efron and Petrosian to access the intrinsic distribution parameters, taking into account the truncations and correlations inherent in the data. We find that the population exhibits strong positive evolution with redshift in both wavebands, with somewhat greater radio evolution than optical. With the luminosity evolutions accounted for, we determine the density evolutions and local radio and optical luminosity functions. The intrinsic distribution of the radio-loudness parameter R is found to be quite different from the observed one and is smooth with no evidence of a bimodality in radio loudness for log R {>=} -1. The results we find are in general agreement with the previous analysis of Singal et al., which used POSS-I optical and FIRST radio data.

  8. SPITZER MID-IR SPECTROSCOPY OF POWERFUL 2 JY AND 3CRR RADIO GALAXIES. I. EVIDENCE AGAINST A STRONG STARBURST-AGN CONNECTION IN RADIO-LOUD AGN

    Energy Technology Data Exchange (ETDEWEB)

    Dicken, D.; Axon, D.; Robinson, A.; Kharb, P. [Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623 (United States); Tadhunter, C.; Ramos Almeida, C. [Department of Physics and Astronomy University of Sheffield, Hounsfield Road, Sheffield, S3 7RH (United Kingdom); Morganti, R. [ASTRON, P.O. Box 2, 7990 AA Dwingeloo (Netherlands); Kouwenhoven, M. B. N. [Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Haidian Qu, Beijing 100871 (China); Spoon, H. [224 Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States); Inskip, K. J. [Max Planck Institute for Astronomy, Koenigstuhl 17, 69117 Heidelberg (Germany); Holt, J. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Nesvadba, N. P. H., E-mail: daniel.dicken@ias.u-psud.fr [Institut d' Astrophysique Spatiale, CNRS, Universite Paris Sud, 91405 Orsay (France)

    2012-02-01

    We present deep Spitzer/Infrared Spectrograph (IRS) spectra for complete samples of 46 2 Jy radio galaxies (0.05 < z < 0.7) and 19 3CRR FRII radio galaxies (z < 0.1), and use the detection of polycyclic aromatic hydrocarbon (PAH) features to examine the incidence of contemporaneous star formation and radio-loud active galactic nucleus (AGN) activity. Our analysis reveals PAH features in only a minority (30%) of the objects with good IRS spectra. Using the wealth of complementary data available for the 2 Jy and 3CRR samples we make detailed comparisons between a range of star formation diagnostics: optical continuum spectroscopy, mid- to far-IR (MFIR) color, far-IR excess and PAH detection. There is good agreement between the various diagnostic techniques: most candidates identified to have star formation activity on the basis of PAH detection are also identified using at least two of the other techniques. We find that only 35% of the combined 2 Jy and 3CRR sample show evidence for recent star formation activity (RSFA) at optical and/or MFIR wavelengths. This result argues strongly against the idea of a close link between starburst and powerful radio-loud AGN activity, reinforcing the view that, although a large fraction of powerful radio galaxies may be triggered in galaxy interactions, only a minority are triggered at the peaks of star formation activity in major, gas-rich mergers. However, we find that compact radio sources (D < 15 kpc) show a significantly higher incidence of RSFA (>75%) than their more extended counterparts ( Almost-Equal-To 15%-25%). We discuss this result in the context of a possible bias toward the selection of compact radio sources triggered in gas-rich environments.

  9. Opening a New Window on the Universe: High-Resolution, Long-Wavelength Radio Astronomy

    National Research Council Canada - National Science Library

    Kassim, Namir

    2002-01-01

    Although Jansky's (1933) discovery of radio astronomy was at decametric wavelengths, the urgent quest for ever higher angular resolution and the fact that ionospheric structure limits interferometric imaging to short (less than 5 km...

  10. Bloqueio "3 em 1" por via anterior: bloqueio parcial, completo ou superdimensionado? Correlação entre anatomia, clínica e radio imagens Bloqueo "3 en 1" por vía anterior: bloqueo parcial, completo o superdimensionado? Correlación entre anatomía, clínica y radio imágenes Anterior "3-in-1" blockade: partial, total or overdimensioned block? Correlation between anatomy, clinic and radio images

    Directory of Open Access Journals (Sweden)

    Karl Otto Geier

    2004-08-01

    participación eventual del nervio genitofemoral (bloqueo "2,5 en 1", uno de los ramos del nervio femoral. Todavía, cuando fueron utilizados catéteres cortos (G2, se obteve bloqueo "3 en 1" en apenas un paciente, al paso que con catéteres largos (G3 introducidos en el sentido cefálico até 18 cm en el espacio subfascial ilíaco, tres bloqueos "3 en 1" superdimensionados fueron registrados, por el envolvimiento adicional de los nervios fibular común en dos pacientes y el nervio tibial en un paciente. CONCLUSIONES: A pesar de la pequeña muestra, con inyección única (G1, siempre se obtuvo un bloqueo "2 en 1" ó "2,5 en 1", sin la participación del nervio obturador. Con catéter corto (G2, el bloqueo "3 en 1" fue clasificado como completo en 6,6% de los casos (un paciente. Mas, con catéter largo (G3, el resultado tiende a ser más previsible en relación a los otros grupos, especialmente cuando el catéter alcanza el espacio paravertebral lombosacral, resultando en un bloqueo "3 en 1" completo en 20% de los casos (tres pacientes o, raramente, en un bloqueo "3 en 1" superdimensionado en 13,2% de los casos (dos pacientes.BACKGROUND AND OBJECTIVES: Classic anterior 3-in-1 blockade has been questioned as to the anesthetic involvement of its three participant nerves: femoral, lateral cutaneous of thigh and obturator. This study aimed at evaluating the outcome of anterior 3-in-1 blockade through: single injection (G1, short catheters (G2 and long catheters (G3. 3-in-1 blockades identified as total or overdimensioned were additionally investigated by radio images. METHODS: The identification of iliac subfascial space in 3-in-1 blockades with single injection or catheters has been made by loss of resistance to air. In several painful events, anesthetic volume has varied 30 to 40 mL and cranial catheters introduction was up to 18 cm in the iliac subfascial space. When clinical research would point to the involvement of the obturator nerve or other nerve additional to 3-in-1

  11. Radio frequency phototube

    Science.gov (United States)

    Margaryan, Amur [Yerevan, AM; Gynashyan, Karlen [Yerevan, AM; Hashimoto, Osamu [Sendai, JP; Majewski, Stanislaw [Morgantown, WV; Tang, Linguang [Yorktown, VA; Marikyan, Gagik [Yerevan, AM; Marikyan, legal representative, Lia

    2012-03-20

    A method and apparatus of obtaining a record of repetitive optical or other phenomena having durations in the picosecond range, comprising a circular scan electron tube to receive light pulses and convert them to electron images consisting with fast nanosecond electronic signals, a continuous wave light or other particle pulses, e.g. electron picosecond pulses, and a synchronizing mechanism arranged to synchronize the deflection of the electron image (images) in the tube (tubes) with the repetition rate of the incident pulse train. There is also provided a method and apparatus for digitization of a repetitive and random optical waveform with a bandwidth higher than 10 GHz.

  12. WEAK AND COMPACT RADIO EMISSION IN EARLY HIGH-MASS STAR-FORMING REGIONS. I. VLA OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Rosero, V.; Hofner, P. [Physics Department, New Mexico Tech, 801 Leroy Pl., Socorro, NM 87801 (United States); Claussen, M. [National Radio Astronomy Observatory, 1003 Lopezville Rd., Socorro, NM 87801 (United States); Kurtz, S.; Carrasco-González, C.; Rodríguez, L. F.; Loinard, L. [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Morelia 58090, México (Mexico); Cesaroni, R. [INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Araya, E. D. [Physics Department, Western Illinois University, 1 University Circle, Macomb, IL 61455 (United States); Menten, K. M.; Wyrowski, F. [Max-Planck-Institute für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Ellingsen, S. P. [School of Physical Sciences, University of Tasmania, Private Bag 37, Hobart, Tasmania 7001 (Australia)

    2016-12-01

    We present a high-sensitivity radio continuum survey at 6 and 1.3 cm using the Karl G. Jansky Very Large Array toward a sample of 58 high-mass star-forming regions. Our sample was chosen from dust clumps within infrared dark clouds with and without IR sources (CMC–IRs and CMCs, respectively), and hot molecular cores (HMCs), with no previous, or relatively weak radio continuum detection at the 1 mJy level. Due to the improvement in the continuum sensitivity of the Very Large Array, this survey achieved map rms levels of ∼3–10  μ Jy beam{sup −1} at sub-arcsecond angular resolution. We extracted 70 continuum sources associated with 1.2 mm dust clumps. Most sources are weak, compact, and prime candidates for high-mass protostars. Detection rates of radio sources associated with the millimeter dust clumps for CMCs, CMC–IRs, and HMCs are 6%, 53%, and 100%, respectively. This result is consistent with increasing high-mass star formation activity from CMCs to HMCs. The radio sources located within HMCs and CMC–IRs occur close to the dust clump centers, with a median offset from it of 12,000 au and 4000 au, respectively. We calculated 5–25 GHz spectral indices using power-law fits and obtained a median value of 0.5 (i.e., flux increasing with frequency), suggestive of thermal emission from ionized jets. In this paper we describe the sample, observations, and detections. The analysis and discussion will be presented in Paper II.

  13. RadioBOT: A spatial cognitive radio testbed

    Science.gov (United States)

    Beck, Brian M.; Kim, Joseph H.; Baxley, Robert J.; Walkenhorst, Brett T.

    This paper introduces RadioBOT, a flexible system of mobile robots for acquisition of radio frequency data. The motivation for such a test system is described, namely the difficulty in acquiring real world data for the purpose of spatial cognitive radio (CR) research. Some current areas of CR research are presented for which RadioBOT can gather data. We then describe the hardware and software components of our system. As a demonstration of the system's capability, we present here the results of a spectrum mapping experiment. In this experiment, we uniformly sample average signal power in a laboratory hallway where an emitter is present. From this data, we form an interpolated spectrum map of the signal power as a function of space. Knowledge of the area's spectrum map is then used to optimize the relay channel communication rate between a transmitter and receiver, by optimally positioning the relay node.

  14. LOFAR MSSS: The scaling relation between AGN cavity power and radio luminosity at low radio frequencies

    Science.gov (United States)

    Kokotanekov, G.; Wise, M.; Heald, G. H.; McKean, J. P.; Bîrzan, L.; Rafferty, D. A.; Godfrey, L. E. H.; de Vries, M.; Intema, H. T.; Broderick, J. W.; Hardcastle, M. J.; Bonafede, A.; Clarke, A. O.; van Weeren, R. J.; Röttgering, H. J. A.; Pizzo, R.; Iacobelli, M.; Orrú, E.; Shulevski, A.; Riseley, C. J.; Breton, R. P.; Nikiel-Wroczyński, B.; Sridhar, S. S.; Stewart, A. J.; Rowlinson, A.; van der Horst, A. J.; Harwood, J. J.; Gürkan, G.; Carbone, D.; Pandey-Pommier, M.; Tasse, C.; Scaife, A. M. M.; Pratley, L.; Ferrari, C.; Croston, J. H.; Pandey, V. N.; Jurusik, W.; Mulcahy, D. D.

    2017-09-01

    We present a new analysis of the widely used relation between cavity power and radio luminosity in clusters of galaxies with evidence for strong AGN feedback. We studied the correlation at low radio frequencies using two new surveys - the first alternative data release of the TIFR GMRT Sky Survey (TGSS ADR1) at 148 MHz and LOFAR's firstall-sky survey, the Multifrequency Snapshot Sky Survey (MSSS) at 140 MHz. We find a scaling relation Pcav ∝ Lβ148, with a logarithmic slope of β = 0.51 ± 0.14, which is in good agreement with previous results based on data at 327 MHz. The large scatter present in this correlation confirms the conclusion reached at higher frequencies that the total radio luminosity at a single frequency is a poor predictor of the total jet power. Previous studies have shown that the magnitude of this scatter can be reduced when bolometric radio luminosity corrected for spectral aging is used. We show that including additional measurements at 148 MHz alone is insufficient to improve this correction and further reduce the scatter in the correlation. For a subset of four well-resolved sources, we examined the detected extended structures at low frequencies and compare with the morphology known from higher frequency images and Chandra X-ray maps. In the case of Perseus we discuss details in the structures of the radio mini-halo, while in the 2A 0335+096 cluster we observe new diffuse emission associated with multiple X-ray cavities and likely originating from past activity. For A2199 and MS 0735.6+7421, we confirm that the observed low-frequency radio lobes are confined to the extents known from higher frequencies. This new low-frequency analysis highlights the fact that existing cavity power to radio luminosity relations are based on a relatively narrow range of AGN outburst ages. We discuss how the correlation could be extended using low frequency data from the LOFAR Two-metre Sky Survey (LoTSS) in combination with future, complementary deeper X

  15. Foundations for radio frequency engineering

    CERN Document Server

    Geyi, Wen

    2015-01-01

    The book provides a comprehensive coverage of the fundamental topics in microwave engineering, antennas and wave propagation, and electromagnetic compatibility, including electromagnetic boundary value problems, waveguide theory, microwave resonators, antennas and wave propagation, microwave circuits, principles of electromagnetic compatibility designs, information theory and systems. Deals systematically with fundamental problems in radio frequency engineering, this important volume provides an updated treatment of radio frequency theory and techniques. The book can be used as a one-semester course for senior and first-year graduate students or as a reference for radio frequency engineers and applied physicists.

  16. La radio en el ciberespacio

    Directory of Open Access Journals (Sweden)

    Ricardo Horvath

    2015-01-01

    Full Text Available Mientras la radio comunitaria se esfuerza por sobrevivir ante la carencia de leyes de radiodifusión que la protejan, sin fondos económicos ni posibilidades ciertas de expansión, la sofisticada radio digital por satélite (DAB ya es un hecho. Su presencia en el ciberespacio permitirá a los grupos multinacionales difundir sus productos culturales a escala mundial, con calidad de CD, y liquidar las programaciones locales. En este contexto, el reto de la radio democrática se multiplica y complica.

  17. Discovery of a Giant Radio Halo in a Massive Merging Cluster at z ...

    Indian Academy of Sciences (India)

    tively. The resulting wide-field image at 610 MHz of the area surrounding the cluster. MACSJ0417.5-1154 is shown in Fig. 1. The radio emission from the central region of the cluster is overlayed on the X-ray emission from the cluster in Fig. 2. An overlay of the 610 MHz radio emission on the 235 MHz image is shown in Fig.

  18. Radio channel measurement and modelling for future mobile radio systems

    Science.gov (United States)

    Guerdenli, E.; Huish, P. W.

    1989-12-01

    Digital mobile radio systems will require planning methods that provide accurate predictions of signal strength, distortion, and interference for situations ranging from very small cells in dense urban locations to large rural cells. Topographic and land usage data bases will find increasing use to enhance the accuracy of prediction models. The implications of these issues are discussed and the work in progress at British Telecommunications Research Laboratories on land mobile radio propagation modeling and wide-band channel measurements is presented.

  19. Radio frequency integrated circuit design for cognitive radio systems

    CERN Document Server

    Fahim, Amr

    2015-01-01

    This book fills a disconnect in the literature between Cognitive Radio systems and a detailed account of the circuit implementation and architectures required to implement such systems.  Throughout the book, requirements and constraints imposed by cognitive radio systems are emphasized when discussing the circuit implementation details.  In addition, this book details several novel concepts that advance state-of-the-art cognitive radio systems.  This is a valuable reference for anybody with background in analog and radio frequency (RF) integrated circuit design, needing to learn more about integrated circuits requirements and implementation for cognitive radio systems. ·         Describes in detail cognitive radio systems, as well as the circuit implementation and architectures required to implement them; ·         Serves as an excellent reference to state-of-the-art wideband transceiver design; ·         Emphasizes practical requirements and constraints imposed by cognitive radi...

  20. Radio Galaxy Zoo: Compact and extended radio source classification with deep learning

    Science.gov (United States)

    Lukic, V.; Brüggen, M.; Banfield, J. K.; Wong, O. I.; Rudnick, L.; Norris, R. P.; Simmons, B.

    2018-01-01

    Machine learning techniques have been increasingly useful in astronomical applications over the last few years, for example in the morphological classification of galaxies. Convolutional neural networks have proven to be highly effective in classifying objects in image data. The current work aims to establish when multiple components are present, in the astronomical context of synthesis imaging observations of radio sources. To this effect, we design a convolutional neural network to differentiate between different morphology classes using sources from the Radio Galaxy Zoo (RGZ) citizen science project. In this first step, we focus on exploring the factors that affect the performance of such neural networks, such as the amount of training data, number and nature of layers and the hyperparameters. We begin with a simple experiment in which we only differentiate between two extreme morphologies, using compact and multiple component extended sources. We found that a three convolutional layer architecture yielded very good results, achieving a classification accuracy of 97.4% on a test data set. The same architecture was then tested on a four-class problem where we let the network classify sources into compact and three classes of extended sources, achieving a test accuracy of 93.5%. The best-performing convolutional neural network setup has been verified against RGZ Data Release 1 where a final test accuracy of 94.8% was obtained, using both original and augmented images. The use of sigma clipping does not offer a significant benefit overall, except in cases with a small number of training images.

  1. Images.

    Science.gov (United States)

    Barr, Catherine, Ed.

    1997-01-01

    The theme of this month's issue is "Images"--from early paintings and statuary to computer-generated design. Resources on the theme include Web sites, CD-ROMs and software, videos, books, and others. A page of reproducible activities is also provided. Features include photojournalism, inspirational Web sites, art history, pop art, and myths. (AEF)

  2. A CONTINUUM HARD-SPHERE MODEL OF PROTEIN ADSORPTION.

    Science.gov (United States)

    Finch, Craig; Clarke, Thomas; Hickman, James J

    2013-07-01

    Protein adsorption plays a significant role in biological phenomena such as cell-surface interactions and the coagulation of blood. Two-dimensional random sequential adsorption (RSA) models are widely used to model the adsorption of proteins on solid surfaces. Continuum equations have been developed so that the results of RSA simulations can be used to predict the kinetics of adsorption. Recently, Brownian dynamics simulations have become popular for modeling protein adsorption. In this work a continuum model was developed to allow the results from a Brownian dynamics simulation to be used as the boundary condition in a computational fluid dynamics (CFD) simulation. Brownian dynamics simulations were used to model the diffusive transport of hard-sphere particles in a liquid and the adsorption of the particles onto a solid surface. The configuration of the adsorbed particles was analyzed to quantify the chemical potential near the surface, which was found to be a function of the distance from the surface and the fractional surface coverage. The near-surface chemical potential was used to derive a continuum model of adsorption that incorporates the results from the Brownian dynamics simulations. The equations of the continuum model were discretized and coupled to a CFD simulation of diffusive transport to the surface. The kinetics of adsorption predicted by the continuum model closely matched the results from the Brownian dynamics simulation. This new model allows the results from mesoscale simulations to be incorporated into micro- or macro-scale CFD transport simulations of protein adsorption in practical devices.

  3. A Framework for Health Communication Across the HIV Treatment Continuum

    Science.gov (United States)

    Van Lith, Lynn M.; Mallalieu, Elizabeth C.; Packman, Zoe R.; Myers, Emily; Ahanda, Kim Seifert; Harris, Emily; Gurman, Tilly; Figueroa, Maria-Elena

    2017-01-01

    Background: As test and treat rolls out, effective interventions are needed to address the determinants of outcomes across the HIV treatment continuum and ensure that people infected with HIV are promptly tested, initiate treatment early, adhere to treatment, and are virally suppressed. Communication approaches offer viable options for promoting relevant behaviors across the continuum. Conceptual Framework: This article introduces a conceptual framework, which can guide the development of effective health communication interventions and activities that aim to impact behaviors across the HIV treatment continuum in low- and medium-income countries. The framework includes HIV testing and counseling, linkage to care, retention in pre-antiretroviral therapy and antiretroviral therapy initiation in one single-stage linkage to care and treatment, and adherence for viral suppression. The determinants of behaviors vary across the continuum and include both facilitators and barriers with communication interventions designed to focus on specific determinants presented in the model. At each stage, relevant determinants occur at the various levels of the social–ecological model: intrapersonal, interpersonal, health services, community, and policy. Effective health communication interventions have mainly relied on mHealth, interpersonal communication through service providers and peers, community support groups, and treatment supporters. Discussion: The conceptual framework and evidence presented highlight areas across the continuum where health communication can significantly impact treatment outcomes to reach the 90-90-90 goals by strategically addressing key behavioral determinants. As test and treat rolls out, multifaceted health communication approaches will be critical. PMID:27930606

  4. Radio broadcasting: an attractive way of broadcasting astronomy

    Science.gov (United States)

    Mosoia, C.

    2008-06-01

    Astronomy is full of beautiful skyscapes, shining stars and huge planets. The vast majority of them can be transformed into tactile images and complemented by audio descriptions. These translations of visual information into raised lines, shapes and textures can be felt with the fingertips instead of viewed with the eyes. In this way, the beauties of the Universe enter the universe of blind and visually impaired people. Happily, we all have radio broadcasting as an important source of information and entertainment. Science radio programmes can bring the real music of the spheres (as Pythagoras once suggested) to the audience.

  5. Jet triggered Type Ia supernovae in radio-galaxies?

    OpenAIRE

    Capetti, Alessandro

    2002-01-01

    We report the serendipitous discovery of a supernova (SN) in the nearby radio-galaxy 3C 78. Observations obtained with the STIS spectrograph on board the Hubble Space Telescope show, at a distance of 0.54 arcsec (300 pc) from the galaxy nucleus, a second bright source, not present in previous images. As this source was fortuitously covered by the spectrograph slit its spectrum was obtained and it is characteristic of a Type Ia SN. This SN is closely aligned with the radio-jet of 3C 78. Analys...

  6. Investigation of Coupled model of Pore network and Continuum in shale gas

    Science.gov (United States)

    Cao, G.; Lin, M.

    2016-12-01

    Flow in shale spanning over many scales, makes the majority of conventional treatment methods disabled. For effectively simulating, a coupled model of pore-scale and continuum-scale was proposed in this paper. Based on the SEM image, we decompose organic-rich-shale into two subdomains: kerogen and inorganic matrix. In kerogen, the nanoscale pore-network is the main storage space and migration pathway so that the molecular phenomena (slip and diffusive transport) is significant. Whereas, inorganic matrix, with relatively large pores and micro fractures, the flow is approximate to Darcy. We use pore-scale network models (PNM) to represent kerogen and continuum-scale models (FVM or FEM) to represent matrix. Finite element mortars are employed to couple pore- and continuum-scale models by enforcing continuity of pressures and fluxes at shared boundary interfaces. In our method, the process in the coupled model is described by pressure square equation, and uses Dirichlet boundary conditions. We discuss several problems: the optimal element number of mortar faces, two categories boundary faces of pore network, the difference between 2D and 3D models, and the difference between continuum models FVM and FEM in mortars. We conclude that: (1) too coarse mesh in mortars will decrease the accuracy, while too fine mesh will lead to an ill-condition even singular system, the optimal element number is depended on boundary pores and nodes number. (2) pore network models are adjacent to two different mortar faces (PNM to PNM, PNM to continuum model), incidental repeated mortar nodes must be deleted. (3) 3D models can be replaced by 2D models under certain condition. (4) FVM is more convenient than FEM, for its simplicity in assigning interface nodes pressure and calculating interface fluxes. This work is supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB10020302), the 973 Program (2014CB239004), the Key Instrument Developing Project of the

  7. Reconfigurable, Digital EVA Radio Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The nature of human exploration missions to the Moon and Mars demands a frequency-agile, reconfigurable, durable digital radio delivering telemetry, ranging, voice,...

  8. Radio Wave Propagation in Tunnels

    National Research Council Canada - National Science Library

    Lee, Jeho

    2000-01-01

    This report examines the radio propagation model for narrow and long tunnels. Modal analysis is used to model the path gain in 2-D and 3-D rectangular tunnels and the coupling loss of L, T and cross tunnels...

  9. Reconfigurable, Digital EVA Radio Project

    Data.gov (United States)

    National Aeronautics and Space Administration — AeroAstro proposes to develop a low-power, low-volume and lightweight, state-of-the-art digital radio capable of operating in a wide variety of bands, from VHF...

  10. Miniaturized Digital EVA Radio Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Bennett Aerospace and Team Partners propose to develop a small, lightweight, and very power-efficient mobile radio for use on the Lunar surface. Our Team will...

  11. Sea Turtle Radio Telemetry Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Radio transmitters attached to sea turtles captured in various fishing gear enabled us to track and measure surfacing time of each turtle. Determining location of...

  12. Innovativeness and the Public Radio Audience.

    Science.gov (United States)

    Williams, Wenmouth, Jr.; Krugman, Dean M.

    1981-01-01

    A public radio audience was surveyed to test the hypothesis that a relationship exists between innovativeness and public radio listening. Rather than supporting the hypothesis, findings indicate that the entertainment and information elements of public radio are the primary attractions for the public radio audience. (MER)

  13. On the evaluation of Web Radio

    NARCIS (Netherlands)

    Field, A.N.; Hartel, Pieter H.

    We develop an evaluation method for Web radio, and perform it to see what we can be learnt about seven prominent Web radio sites. We also evaluate a commercial FM radio station for control purposes. We present a taxonomy of Web radio, and we give our observations and conclusions on this evaluation.

  14. Ecuador: Construyendo radio y pueblo

    OpenAIRE

    Teodoro Galarza

    2015-01-01

    En el Ecuador a diferencia de Argentina y Colombia, las radios populares crecen a ritmo lento. En la década pasada hubo estancamiento, pero en los años 90 hay un resurgir de estos medios, con nuevos estilos de trabajo. La coordinadora de radios Populares y Educativas del Ecuador, CORAPE, sigue de cerca esta evolución. El texto trata de la capacitación profesional.

  15. Radio and line transmission 2

    CERN Document Server

    Roddy, Dermot

    2013-01-01

    Radio and Line Transmission, Volume 2 gives a detailed treatment of the subject as well as an introduction to additional advanced subject matter. Organized into 14 chapters, this book begins by explaining the radio wave propagation, signal frequencies, and bandwidth. Subsequent chapters describe the transmission lines and cables; the aerials; tuned and coupled circuits; bipolar transistor amplifiers; field-effect transistors and circuits; thermionic valve amplifiers; LC oscillators; the diode detectors and modulators; and the superheterodyne receiver. Other chapters explore noise and interfere

  16. Interoperability: Stop Blaming the Radio

    Science.gov (United States)

    2007-02-01

    Interoperability: Stop Blaming the Radio Ronald P. Timmons INTRODUCTION One of the most pressing first responder issues emerging in the post-9...00-00-2007 4. TITLE AND SUBTITLE Interoperability: Stop Blaming the Radio 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...recording of a reporter describing the crash of the Hindenburg (“oh, the humanity!”) can attest, stress causes the human voice to take on a very

  17. Ecuador: Construyendo radio y pueblo

    Directory of Open Access Journals (Sweden)

    Teodoro Galarza

    2015-01-01

    Full Text Available En el Ecuador a diferencia de Argentina y Colombia, las radios populares crecen a ritmo lento. En la década pasada hubo estancamiento, pero en los años 90 hay un resurgir de estos medios, con nuevos estilos de trabajo. La coordinadora de radios Populares y Educativas del Ecuador, CORAPE, sigue de cerca esta evolución. El texto trata de la capacitación profesional.

  18. Automatic radio-transmission monitor

    Science.gov (United States)

    Bernstein, A. J.

    1978-01-01

    System continuously monitors radio transmissions stored in memory. If spectrum deviates beyond present limits, alarm is tripped and spectrum is transferred to long-term storage for later analysis. Monitor can be useful in ensuring proper power level and spectral quality and in finding cause of failure. It might also be used to monitor radio-frequency interference or power levels of citizen's-band transmitters.

  19. A zero-power radio receiver.

    Energy Technology Data Exchange (ETDEWEB)

    Brocato, Robert Wesley

    2004-09-01

    This report describes both a general methodology and some specific examples of passive radio receivers. A passive radio receiver uses no direct electrical power but makes sole use of the power available in the radio spectrum. These radio receivers are suitable as low data-rate receivers or passive alerting devices for standard, high power radio receivers. Some zero-power radio architectures exhibit significant improvements in range with the addition of very low power amplifiers or signal processing electronics. These ultra-low power radios are also discussed and compared to the purely zero-power approaches.

  20. RADIO WITHOUT A LISTENER: "MAYAK"

    Directory of Open Access Journals (Sweden)

    Bysko Maxim V.

    2017-12-01

    Full Text Available The singularity of this article is that it is entirely based on a critical analysis of only one live musical radio program on the Mayak radio station and dedicated to the life and work of the famous British composer Andrew Lloyd Webber. In principle, the article can be considered a scientific review of the media product. Based on his analysis, the author comes to the paradoxical conclusion that the presence of a listener becomes unnecessary for modern broadcasting. This is stated by many principles of the conduct of the air, presented in the radio program, where all the information load is placed on the guest in the studio, where there is no preparatory work of the DJs, where their inability to navigate the genres of journalism violates communication norms and colloquial ethics, where an obvious deconstructive approach to the material offered for the listener. In addition, the phenomenon of being the DJs in the radio studio exclusively "for themselves" is emphasized by the sound design of the radio program, which runs counter to the logic of auditory perception (for example, the sequence of jingles, as well as the incompetent selection of musical material, which undoubtedly repels professional radio listeners-musicians.