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Sample records for lac object 1es

  1. HST/COS Observations of the Ly alpha Forest toward the BL Lac Object 1ES1553+113

    CERN Document Server

    Danforth, Charles W; Stocke, John T; Shull, J Michael; Yao, Yangsen

    2010-01-01

    We present new far-ultraviolet spectra from the Cosmic Origins Spectrograph (HST/COS) of the BL Lac object 1ES1553+113 covering the wavelength range 1135-1795 A. The data show a smooth continuum with a wealth of narrow absorption features arising in the ISM and IGM. These features include 41 Lya absorbers at 00.6 for the strongest component of the absorber complex. Galaxy redshift surveys show a number of massive galaxies at approximately the same redshift as this absorption complex, suggesting that it arises in a large-scale galaxy filament. As one of the brightest extragalactic X-ray and gamma-ray sources, 1ES1553+113 is of great interest to the high-energy astrophysics community. With no intrinsic emission or absorption features, 1ES1553+113 has no direct redshift determination. We use intervening Lya absorbers to place a direct limit on the redshift: z_em>0.395 based on a confirmed Lya+OVI absorber and z_em>0.433 based on a single-line detection of Lya. COS/FUV data are only sensitive to Lya absorbers at ...

  2. VERITAS long-term (2006-2014) observations of the BL Lac object 1ES 0806+524

    CERN Document Server

    Cerruti, Matteo

    2015-01-01

    The discovery of the high-frequency-peaked BL Lac object 1ES 0806+524 (z=0.138) as a source of very-high-energy (VHE, E>100 GeV) gamma-ray photons was announced in 2008 by the VERITAS Collaboration, at a level of 1.8% of the Crab Nebula flux above 300 GeV. Since then, VERITAS has continued observing the source over multiple seasons, significantly improving the significance of the detection. We report the results of the analysis of the 2006-2014 VERITAS data, corresponding to a total exposure of about 70 hours. We present the new, average VHE spectrum of the source, together with the multi-year light-curve constraining long-term VHE variability.

  3. Long term lightcurve of the BL Lac object 1ES 0229+200 at TeV energies

    CERN Document Server

    Cologna, Gabriele; Wagner, Stefan J; Wierzcholska, Alicja; Romoli, Carlo; Kurtanidze, Omar

    2015-01-01

    The high-frequency peaked BL Lac object 1ES 0229+200 (z = 0.14) was first detected in very high energy (VHE, E > 100 GeV) $\\gamma$-rays by the H.E.S.S. (High Energy Stereoscopic System) collaboration in 2006. No flux variability was reported in the initial study and its spectral characteristics have been used to derive constraints on the extragalactic background light (EBL) and on the intergalactic magnetic field (IGMF). 1ES 0229+200 has been observed with H.E.S.S. for $\\sim$130 hours from 2004 to 2013: the full dataset analysed with a more sensitive method will be presented here. The results indicate that the source is not constant and displays flux variability on yearly and monthly timescales. The existence of flux variability affects the derivation of the constraints on the IGMF. The H.E.S.S. observations cover several simultaneous multi-frequency campaigns and the VHE variations are compared with those reported in different bands.

  4. Discovery of hard-spectrum \\gamma-ray emission from the BL Lac object 1ES 0414+009

    CERN Document Server

    Abramowski, A; Aharonian, F; Akhperjanian, A G; Anton, G; Balzer, A; Barnacka, A; de Almeida, U Barres; Becherini, Y; Becker, J; Behera, B; Bernlöhr, K; Birsin, E; Biteau, J; Bochow, A; Boisson, C; Bolmont, J; Bordas, P; Brucker, J; Brun, F; Brun, P; Bulik, T; Büsching, I; Carrigan, S; Casanova, S; Cerruti, M; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Chounet, L -M; Clapson, A C; Coignet, G; Cologna, G; Conrad, J; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubois, F; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Egberts, K; Eger, P; Espigat, P; Fallon, L; Farnier, C; Feinstein, F; Fernandes, M V; Fiasson, A; Fontaine, G; Förster, A; Füßling, M; Gallant, Y A; Gast, H; Gérard, L; Gerbig, D; Giebels, B; Glicenstein, J F; Glück, B; Goret, P; Göring, D; Häffner, S; Hague, J D; Hampf, D; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hoffmann, A; Hofmann, W; Hofverberg, P; Holler, M; Horns, D; Jacholkowska, A; de Jager, O C; Jahn, C; Jamrozy, M; Jung, I; Kastendieck, M A; Katarzynski, K; Katz, U; Kaufmann, S; Keogh, D; Khangulyan, D; Khélifi, B; Kluźniak, D Klochkov W; Kneiske, T; Komin, Nu; Kosack, K; Kossakowski, R; Laffon, H; Lamanna, G; Lennarz, D; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Masbou, J; Maurin, D; Maxted, N; Mayer, M; McComb, T J L; Medina, M C; Méhault, J; Moderski, R; Moulin, E; Naumann, C L; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nekrassov, D; Nguyen, N; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Wilhelmi, E de Ona; Opitz, B; Ostrowski, M; Oya, I; Panter, M; Arribas, M Paz; Pedaletti, G; Pelletier, G; Petrucci, P -O; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raue, M; Rayner, S M; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Ruppel, J; Sahakian, V; Sanchez, D A; Santangelo, A; Schlickeiser, R; Schöck, F M; Schulz, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Sheidaei, F; Sikora, M; Skilton, J L; Sol, H; Spengler, G; Stawarz, L; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Szostek, A; Tavernet, J -P; Terrier, R; Tluczykont, M; Valerius, K; van Eldik, C; Vasileiadis, G; Venter, C; Vialle, J P; Viana, A; Vincent, P; Völk, H J; Volpe, F; Vorobiov, S; Vorster, M; Wagner, S J; Ward, M; White, R; Wierzcholska, A; Zacharias, M; Zajczyk, A; Zdziarski, A A; Zech, A; Zechlin, H -S; Costamante, L; Fegan, S; Ajello, M

    2012-01-01

    1ES 0414+009 (z = 0.287) is a distant high-frequency-peaked BL Lac object, and has long been considered a likely emitter of very-high energy (VHE, E>100 GeV) gamma-rays due to its high X-ray and radio flux. Observations in the VHE gamma-ray band and across the electromagnetic spectrum can provide insights into the origin of highly energetic particles present in the source and the radiation processes at work. Because of the distance of the source, the gamma-ray spectrum might provide further limits on the level of the Extragalactic Background Light (EBL). We report observations made between October 2005 and December 2009 with H.E.S.S., an array of four imaging atmospheric Cherenkov telescopes. Observations at high energies (HE, 100 MeV - 100 GeV) with the Fermi-LAT instrument in the first 20 months of its operation are also reported. To complete the multi-wavelength picture, archival UV and X-ray observations with the Swift satellite and optical observations with the ATOM telescope are also used. Based on the ...

  5. MAGIC detection of short-term variability of the high-peaked BL Lac object 1ES 0806+524

    CERN Document Server

    Aleksić, J; Antonelli, L A; Antoranz, P; Babic, A; Bangale, P; Barrio, J A; González, J Becerra; Bednarek, W; Bernardini, E; Biasuzzi, B; Biland, A; Blanch, O; Bonnefoy, S; Bonnoli, G; Borracci, F; Bretz, T; Carmona, E; Carosi, A; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Caneva, G; De Lotto, B; Wilhelmi, E de O na; Mendez, C Delgado; Di Pierro, F; Prester, D Dominis; Dorner, D; Doro, M; Einecke, S; Eisenacher, D; Elsaesser, D; Fernández-Barral, A; Fidalgo, D; Fonseca, M V; Font, L; Frantzen, K; Fruck, C; Galindo, D; López, R J García; Garczarczyk, M; Terrats, D Garrido; Gaug, M; Godinović, N; noz, A González Mu; Gozzini, S R; Hadasch, D; Hanabata, Y; Hayashida, M; Herrera, J; Hose, J; Hrupec, D; Idec, W; Kadenius, V; Kellermann, H; Knoetig, M L; Kodani, K; Konno, Y; Krause, J; Kubo, H; Kushida, J; La Barbera, A; Lelas, D; Lewandowska, N; Lindfors, E; Lombardi, S; Longo, F; López, M; López-Coto, R; López-Oramas, A; Lorenz, E; Lozano, I; Makariev, M; Mallot, K; Maneva, G; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martínez, M; Mazin, D; Menzel, U; Miranda, J M; Mirzoyan, R; Moralejo, A; Munar-Adrover, P; Nakajima, D; Neustroev, V; Niedzwiecki, A; Rosillo, M Nievas; Nilsson, K; Nishijima, K; Noda, K; Orito, R; Overkemping, A; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, J M; Paredes-Fortuny, X; Persic, M; Poutanen, J; Moroni, P G Prada; Prandini, E; Puljak, I; Reinthal, R; Rhode, W; Ribó, M; Rico, J; Garcia, J Rodriguez; Saito, T; Saito, K; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Shore, S N; Sillanpää, A; Sitarek, J; Snidaric, I; Sobczynska, D; Stamerra, A; Steinbring, T; Strzys, M; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzić, T; Tescaro, D; Teshima, M; Thaele, J; Torres, D F; Toyama, T; Treves, A; Vogler, P; Will, M; Zanin, R; Berger, K; Buson, S; D'Ammando, F; Gasparrini, D; Hovatta, T; Max-Moerbeck, W; Readhead, A; Richards, J

    2015-01-01

    The high-frequency-peaked BL Lac (HBL) 1ES 0806+524 (z = 0.138) was discovered in VHE $\\gamma$ rays in 2008. Until now, the broad-band spectrum of 1ES 0806+524 has been only poorly characterized, in particular at high energies. We analysed multiwavelength observations from $\\gamma$ rays to radio performed from 2011 January to March, which were triggered by the high activity detected at optical frequencies. These observations constitute the most precise determination of the broad-band emission of 1ES 0806+524 to date. The stereoscopic MAGIC observations yielded a $\\gamma$-ray signal above 250 GeV of $(3.7 \\pm 0.7)$ per cent of the Crab Nebula flux with a statistical significance of 9.9 $\\sigma$. The multiwavelength observations showed significant variability in essentially all energy bands, including a VHE $\\gamma$-ray flare that lasted less than one night, which provided unprecedented evidence for short-term variability in 1ES 0806+524. The spectrum of this flare is well described by a power law with a photon...

  6. Studies of inverse-Compton emission in the Crab Nebula and the BL Lac object 1ES 1959+650

    Science.gov (United States)

    O'Faolain de Bhroithe, Anna

    This thesis concerns the study of inverse-Compton emission from two astrophysical sources. The first object, 1ES 1959+650, is a nearby active galactic nucleus. This source was observed as part of the VERITAS blazar monitoring programme in the hopes of detecting it in the midst of a dramatic flaring event. Over the course of these monitoring observations which span four years, a significant detection of the source in its low state was accumulated. The spectral energy distribution of this source was analysed from optical to VHE and was modelled with a synchrotron self-Compton model with an additional external Compton component. The parameters obtained cannot be fully explained by first-order Fermi acceleration at parallel shocks, and instead may suggest particle acceleration at oblique subluminal shocks, or that 1ES 1959+650 may consist of an inhomogeneous jet with a fast inner spine and slower-moving outer cocoon. The second source is the famous Crab Nebula, for years considered the standard candle of X-ray to VHE gamma-ray astronomy. VERITAS observed the Crab Nebula during the recent flare of the high-energy synchrotron component of the source in March 2013. No enhanced VHE emission was detected, but the observations facilitated the calculation of upper limits on any extra VHE spectral component emerging during the flare. A wealth of archival VHE Crab Nebula data also exists, spanning many years. An extended VHE data set of the source from 2000 to 2013 was compiled from Whipple 10m Telescope and VERITAS observations. This data set was searched for short-term flaring activity, but no evidence of this behaviour was found. A slight decrease in the long-term flux of the nebula was detected in the VERITAS data in 2011. This could possibly be correlated with increasing instability of the aerosol content of the local atmosphere around the VERITAS site.

  7. Fermi LAT detection of increasing GeV gamma-ray activity from the high-energy peaked BL Lac object 1ES 1959+650

    Science.gov (United States)

    Ciprini, Stefano; Fermi Large Area Telescope Collaboration

    2015-10-01

    The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray emission from a source positionally consistent with the very-high energy peaked BL Lac object 1ES 1959+650 (also known as TXS 1959+650 and 3FGL J2000.0+6509, Acero et al. 2015, ApJS 218, 23) with radio coordinates (J2000) R.A.: 299.999384 deg, Dec.: 65.148514 deg (Beasley et al. 2002, ApJS, 141, 13). This source has a redshift z=0.047 (Schachter et al. 1993, ApJ, 412, 541).

  8. Fermi-LAT, FACT, MAGIC and VERITAS detection of increasing gamma-ray activity from the high-energy peaked BL Lac object 1ES 1959+650

    Science.gov (United States)

    Buson, S.; Magill, J. D.; Dorner, D.; Biland, A.; Mirzoyan, R.; Mukherjee, R.

    2016-04-01

    The Fermi-LAT, FACT, MAGIC and VERITAS collaborations report the detection of enhanced gamma-ray activity from a source positionally consistent with the very-high-energy peaked BL Lac object 1ES 1959+650 (a.k.a 3FGL J2000.0+6509, in the 3rd LAT source catalog, 3FGL, Acero et al. 2015, ApJS 218, 23) with radio coordinates (J2000) R.A.: 299.999384 deg, Dec.: 65.148514 deg (Beasley et al. 2002, ApJS, 141, 13). This source has a redshift z=0.047 (Schachter et al. 1993, ApJ, 412, 541).

  9. VERITAS detection of $\\gamma$-ray flaring activity from the BL Lac object 1ES 1727+502 during bright moonlight observations

    CERN Document Server

    Archambault, S; Beilicke, M; Benbow, W; Bird, R; Biteau, J; Bouvier, A; Bugaev, V; Cardenzana, J V; Cerruti, M; Chen, X; Ciupik, L; Connolly, M P; Cui, W; Dickinson, H J; Dumm, J; Eisch, J D; Errando, M; Falcone, A; Feng, Q; Finley, J P; Fleischhack, H; Fortin, P; Fortson, L; Furniss, A; Gillanders, G H; Griffin, S; Griffiths, S T; Grube, J; Gyuk, G; Håkansson, N; Hanna, D; Holder, J; Humensky, T B; Johnson, C A; Kaaret, P; Kar, P; Kertzman, M; Khassen, Y; Kieda, D; Krause, M; Krennrich, F; Kumar, S; Lang, M J; Maier, G; McArthur, S; McCann, A; Meagher, K; Millis, J; Moriarty, P; Mukherjee, R; Nieto, D; de Bhróithe, A O'Faoláin; Ong, R A; Otte, A N; Park, N; Pohl, M; Popkow, A; Prokoph, H; Pueschel, E; Quinn, J; Ragan, K; Reyes, L C; Reynolds, P T; Richards, G T; Roache, E; Santander, M; Sembroski, G H; Shahinyan, K; Smith, A W; Staszak, D; Telezhinsky, I; Tucci, J V; Tyler, J; Varlotta, A; Vincent, S; Wakely, S P; Weinstein, A; Welsing, R; Wilhelm, A; Williams, D A; Zitzer, B; Hughes, Z D

    2015-01-01

    During moonlit nights, observations with ground-based Cherenkov telescopes at very high energies (VHE, $E>100$ GeV) are constrained since the photomultiplier tubes (PMTs) in the telescope camera are extremely sensitive to the background moonlight. Observations with the VERITAS telescopes in the standard configuration are performed only with a moon illumination less than 35$\\%$ of full moon. Since 2012, the VERITAS collaboration has implemented a new observing mode under bright moonlight, by either reducing the voltage applied to the PMTs (reduced-high-voltage configuration, RHV), or by utilizing UV-transparent filters. While these operating modes result in lower sensitivity and increased energy thresholds, the extension of the available observing time is useful for monitoring variable sources such as blazars and sources requiring spectral measurements at the highest energies. In this paper we report the detection of $\\gamma$-ray flaring activity from the BL Lac object 1ES 1727+502 during RHV observations. Thi...

  10. VERITAS Detection of γ-Ray Flaring Activity From the BL Lac Object 1ES 1727+502 During Bright Moonlight Observations

    Science.gov (United States)

    Archambault, S.; Archer, A.; Beilicke, M.; Benbow, W.; Bird, R.; Biteau, J.; Bouvier, A.; Bugaev, V.; Cardenzana, J. V.; Cerruti, M.; Chen, X.; Ciupik, L.; Connolly, M. P.; Cui, W.; Dickinson, H. J.; Dumm, J.; Eisch, J. D.; Errando, M.; Falcone, A.; Feng, Q.; Finley, J. P.; Fleischhack, H.; Fortin, P.; Fortson, L.; Furniss, A.; Gillanders, G. H.; Griffin, S.; Griffiths, S. T.; Grube, J.; Gyuk, G.; Håkansson, N.; Hanna, D.; Holder, J.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kertzman, M.; Khassen, Y.; Kieda, D.; Krause, M.; Krennrich, F.; Kumar, S.; Lang, M. J.; Maier, G.; McArthur, S.; McCann, A.; Meagher, K.; Millis, J.; Moriarty, P.; Mukherjee, R.; Nieto, D.; O'Faoláin de Bhróithe, A.; Ong, R. A.; Otte, A. N.; Park, N.; Pohl, M.; Popkow, A.; Prokoph, H.; Pueschel, E.; Quinn, J.; Ragan, K.; Reyes, L. C.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Santander, M.; Sembroski, G. H.; Shahinyan, K.; Smith, A. W.; Staszak, D.; Telezhinsky, I.; Tucci, J. V.; Tyler, J.; Varlotta, A.; Vincent, S.; Wakely, S. P.; Weinstein, A.; Welsing, R.; Wilhelm, A.; Williams, D. A.; Zitzer, B.; Veritas Collaboration; Hughes, Z. D.

    2015-08-01

    During moonlit nights, observations with ground-based Cherenkov telescopes at very high energies (VHEs, E\\gt 100 GeV) are constrained since the photomultiplier tubes (PMTs) in the telescope camera are extremely sensitive to the background moonlight. Observations with the VERITAS telescopes in the standard configuration are performed only with a moon illumination less than 35% of full moon. Since 2012, the VERITAS collaboration has implemented a new observing mode under bright moonlight, by either reducing the voltage applied to the PMTs (reduced-high-voltage; RHV configuration), or by utilizing UV-transparent filters. While these operating modes result in lower sensitivity and increased energy thresholds, the extension of the available observing time is useful for monitoring variable sources such as blazars and sources requiring spectral measurements at the highest energies. In this paper we report the detection of γ-ray flaring activity from the BL Lac object 1ES 1727+502 during RHV observations. This detection represents the first evidence of VHE variability from this blazar. The integral flux is (1.1+/- 0.2)× {10}-11 {{cm}}-2 {{{s}}}-1 above 250 GeV, which is about five times higher than the low-flux state. The detection triggered additional VERITAS observations during standard dark-time. Multiwavelength observations with the FLWO 48″ telescope, and the Swift and Fermi satellites are presented and used to produce the first spectral energy distribution (SED) of this object during γ-ray flaring activity. The SED is then fitted with a standard synchrotron-self-Compton model, placing constraints on the properties of the emitting region and of the acceleration mechanism at the origin of the relativistic particle population in the jet.

  11. A Multiwavelength Study of Flaring Activity in the High-energy Peaked BL Lac Object 1ES 1959+650 During 2015–2016

    Science.gov (United States)

    Kaur, Navpreet; Chandra, S.; Baliyan, Kiran S.; Sameer; Ganesh, S.

    2017-09-01

    We present the results from a multiwavelength study of the flaring activity in the high-energy peaked BL Lac object 1ES 1959+650 during 2015 January–2016 June. The source underwent two major outbursts, during 2015 March and 2015 October, across the whole electromagnetic spectrum (EMS). We used data from Fermi-LAT and Swift-XRT/UVOT, and optical data from Mt. Abu InfraRed Observatory and Steward Observatory to look for possible correlations between the emissions at different energies and the nature of the variability during the flaring state. During the 2015 October outburst, the nightly averaged V-band brightest magnitude, 14.45(0.03), and faintest magnitude, 14.85(0.02), were recorded. Apart from long-term flares, rapid and short-term variabilities were noticed at all energies. Our study suggests that the flaring activities at all frequencies, with diverse flare durations and time lags, are correlated. The magnetic field strength is estimated to be 4 G using the synchrotron-cooling timescale (2.3 hr), and the upper limits on the sizes of both emission regions, γ-ray and optical, are estimated to be of the order of 1016 cm. The quasi-simultaneous flux enhancements in 15 GHz and VHE γ-ray emissions indicate a fresh injection of plasma into the jet, which interacts with a standing submillimeter core, resulting in co-spatial emissions across the EMS. The synchrotron peak shifts to higher frequency in the spectral energy distribution while the γ-ray spectra softens during the flaring. The shape of the inverse-Compton spectra indicates a change in the particle energy distribution pre- and post-flare.

  12. The hard synchrotron X-ray spectrum of the TeV BL Lac 1ES 1426+428

    CERN Document Server

    Wolter, A; Ghisellini, G; Tavecchio, F; Maraschi, L; Costamante, L; Celotti, A; Ghirlanda, G

    2007-01-01

    We have observed 1ES 1426+428 with INTEGRAL detecting it up to $\\sim$150 keV. The spectrum is hard, confirming that this source is an extreme BL Lac object, with a synchrotron component peaking, in a $\

  13. Hard synchrotron BL Lacs the case of 1ES 1101-232

    CERN Document Server

    Wolter, A; Tagliaferri, G; Tavecchio, F; Caccianiga, A; Wolter, Anna; Ghisellini, Gabriele; Tagliaferri, Gianpiero; Tavecchio, Fabrizio; Caccianiga, Alessandro

    2000-01-01

    The bright X-ray selected BL Lac object 1ES1101--232 shows a flat X-ray spectrum, making it detectable with high statistics over the wide BeppoSAX energy range. We have observed it in two different epochs with BeppoSAX, and found a variation of the flux of about 30% that can be explained by a change in the spectral index above the synchrotron peak. We present here the data and infer limits on the strength of the magnetic field based on models of emission for High-frequency peaked BL Lacs.

  14. Whipple Observations of BL Lac Objects

    CERN Document Server

    D'Vali, M; Bradbury, S M; Buckley, J H; Burdett, A M; Carter-Lewis, D A; Catanese, M; Cawley, M F; Fegan, D J; Fegan, S J; Finley, J P; Gaidos, J A; Hall, T A; Hillas, A M; Knapp, J; Krennrich, F; Le Bohec, S; Lessard, R W; Masterson, C; Myles, S D; Quinn, J; Rose, H J; Samuelson, F W; Sembroski, G H; Vasilev, V; Weekes, T C

    1999-01-01

    Only BL Lac objects have been detected as extragalactic sources of very high energy (E > 300 GeV) gamma rays. Using the Whipple Observatory Gamma-ray Telescope, we have attempted to detect more BL Lacs using three approaches. First, we have conducted surveys of nearby BL Lacs, which led to the detections of Mrk 501 and 1ES 2344+514. Second, we have observed X-ray bright BL Lacs when the RXTE All-Sky Monitor identifies high state X-ray emission in an object, in order to efficiently detect extended high emission states. Third, we have conducted rapid observations of several BL Lacs and QSOs located close together in the sky to search for very high flux, short time-scale flare states such as have been seen from Mrk 421. We will present the results of a survey using the third observational technique.

  15. VERITAS observations of the BL Lac 1ES 1218+304

    CERN Document Server

    Acciari, V A; Arlen, T; Beilicke, M; Benbow, W; Bradbury, S M; Buckley, J H; Bugaev, V; Butt, Y; Byrum, K L; Celik, O; Cesarini, A; Ciupik, L; Chow, Y C K; Cogan, P; Colin, P; Cui, W; Daniel, M K; Ergin, T; Falcone, A D; Fegan, S J; Finley, J P; Fortin, P; Fortson, L F; Furniss, A; Gillanders, G H; Grube, J; Guenette, R; Gyuk, G; Hanna, D; Hays, E; Holder, J; Horan, D; Hui, C M; Humensky, T B; Imran, A; Kaaret, Philip; Karlsson, N; Kertzman, M; Kieda, D B; Kildea, J; Konopelko, A; Krawczynski, H; Krennrich, F; Lang, M J; Le Bohec, S; Maier, G; McCann, A; McCutcheon, M; Moriarty, P; Mukherjee, R; Nagai, T; Niemiec, J; Ong, R A; Pandel, D; Perkins, J S; Pohl, M; Quinn, J; Ragan, K; Reyes, L C; Reynolds, P T; Rose, H J; Schroedter, M; Sembroski, G H; Smith, A W; Steele, D; Swordy, S P; Toner, J A; Valcarcel, L; Vasilev, V V; Wagner, R; Wakely, S P; Ward, J E; Weekes, T C; Weinstein, A; White, R J; Williams, D A; Wissel, S A; Wood, M; Zitzer, B

    2009-01-01

    The VERITAS collaboration reports the detection of very-high-energy (VHE) gamma-ray emission from the high-frequency-peaked BL Lac object 1ES 1218+304 located at a redshift of z=0.182. A gamma-ray signal was detected with a statistical significance of 10.4 standard deviations (10.4 sigma) for the observations taken during the first three months of 2007, confirming the discovery of this object made by the MAGIC collaboration. The photon spectrum between ~160 GeV and ~1.8 TeV is well described by a power law with an index of Gamma = 3.08 +/- 0.34_stat +/- 0.2_sys. The integral flux is Phi(E > 200 GeV) = (12.2 +/- 2.6) X 10^-12 cm^-2 s^-1, which corresponds to ~6% of that of the Crab Nebula. The light curve does not show any evidence for VHE flux variability. Using lower limits on the density of the extragalactic background light in the near to mid-infrared we are able to limit the range of intrinsic energy spectra for 1ES 1218+304. We show that the intrinsic photon spectrum has an index that is harder than Gamm...

  16. Discovery of VHE gamma-rays from the distant BL Lac 1ES 0347-121

    CERN Document Server

    Aharonian, F; Barres de Almeida, U; Bazer-Bachi, A R; Behera, B; Beilicke, M; Benbow, W; Bernlöhr, K; Boisson, C; Bolz, O; Borrel, V; Braun, I; Brion, E; Brown, A M; Buhler, R; Bulik, T; Büsching, I; Boutelier, T; Carrigan, S; Chadwick, P M; Chounet, L M; Clapson, A C; Coignet, G; Cornils, R; Costamante, L; Dalton, M; Degrange, B; Dickinson, H J; Djannati-Ata:, A; Domainko, W; O'Connor-Drury, L; Dubois, F; Dubus, G; Dyks, J; Egberts, K; Emmanoulopoulos, D; Espigat, P; Farnier, C; Feinstein, F; Fiasson, A; Förster, A; Fontaine, G; Funk, Seb; Fuling, M; Gallant, Y A; Giebels, B; Glicenstein, J F; Glück, B; Goret, P; Hadjichristidis, C; Hauser, D; Hauser, M; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hoffmann, A; Hofmann, W; Holleran, M; Hoppe, S; Horns, D; Jacholkowska, A; De Jager, O C; Jung, I; Katarzynski, K; Kendziorra, E; Kerschhaggl, M; Khelifi, B; Keogh, D; Komin, Nu; Kosack, K; Lamanna, G; Latham, I J; Lemiere, A; Lemoine-Goumard, M; Lenain, J P; Lohse, T; Martin, J M; Martineau-Huynh, O; Marcowith, A; Masterson, C; Maurin, D; Maurin, G; McComb, T J L; Moderski, R; Moulin, E; De Naurois, Mathieu; Nedbal, D; Nolan, S J; Ohm, S; Olive, J P; De Ona Wilhelmi, E; Orford, K J; Osborne, J L; Ostrowski, M; Panter, M; Pedaletti, G; Pelletier, G; Petrucci, P O; Pita, S; Pühlhofer, G; Punch, M; Ranchon, S; Raubenheimer, B C; Raue, M; Rayner, S M; Renaud, M; Ripken, J; Rob, L; Rolland, L; Rosier-Lees, S; Rowell, G; Rudak, B; Ruppel, J; Sahakian, V V; Santangelo, A; Schlickeiser, R; Schock, F; Schroder, R; Schwanke, U; Schwarzburg, S; Schwemmer, S; Shalchi, A; Sol, H; Spangler, D; Stawarz,; Steenkamp, R; Stegmann, C; Superina, G; Tam, P H; Tavernet, J P; Terrier, R; Van Eldik, C; Vasileiadis, G; Venter, C; Vialle, J P; Vincent, P; Vivier, M; Völk, H J; Volpe, F; Wagner, S J; Ward, M; Zdziarski, A A; Zech, A

    2007-01-01

    Aims: Our aim is to study the production mechanism for very-high-energy (VHE; >100GeV) gamma-rays in distant active galactic nuclei (AGN) and use the observed VHE spectrum to derive limits on the Extragalactic Background Light (EBL). We also want to determine physical quantities through the modeling of the object's broad-band spectral energy distribution (SED). Methods: VHE observations (~25h live time) of the BL Lac 1ES 0347-121 (redshift z=0.188) were conducted with the High Energy Stereoscopic System (H.E.S.S.) between August and December 2006. Contemporaneous X-ray and UV/optical observations from the SWIFT satellite are used to interpret the SED of the source in terms of a synchrotron self Compton (SSC) model. Results: An excess of 327 events, corresponding to a statistical significance of 10.1 standard deviations, is detected from 1ES 0347-121. Its photon spectrum, ranging from ~250GeV to ~3TeV, is well described by a power law with a photon index of Gamma = 3.10 +/- 0.23_stat +/- 0.10_sys. The integral...

  17. A low density of the extragalactic background light revealed by the H.E.S.S. spectra of the BL Lac objects 1ES 1101-232 and H 2356-309

    Science.gov (United States)

    Costamante, Luigi

    2007-06-01

    The study of the TeV emission from extragalactic sources is hindered by the uncertainties on the diffuse Extragalactic Background Light (EBL). The recent H.E.S.S. results on the blazars 1ES 1101-232 and H 2356-309 represent a breakthrough on this issue. Their unexpectedly hard spectra allow an upper limit to be derived on the EBL in the optical/near-infrared range, which is very close to the lower limit given by the resolved galaxy counts. This result seems to exclude a large contribution to the EBL from other sources (e.g. Population III stars) and indicates that the intergalactic space is more transparent to γ-rays than previously thought. A discussion of EBL absorption effects and further observational tests with Cherenkov telescopes are presented.

  18. Detection of Exceptional X-Ray Spectral Variability in the TeV BL Lac 1ES 2344+514

    CERN Document Server

    Giommi, P; Perlman, E S

    1999-01-01

    We present the results of six BeppoSAX observations of 1ES 2344+514, five of which were taken within a week. 1ES 2344+514, one of the few known TeV BL Lac objects, was detected by the BeppoSAX Narrow Field Instruments between 0.1 to large amplitude luminosity variability, associated with spectacular spectral changes, particularly when compared to the last observation when the source was found to be several times fainter, with a much steeper X-ray spectrum. The energy dependent shape of the lightcurve and the spectral changes imply a large shift (factor of 30 or more in frequency) of the peak of the synchrotron emission. At maximum flux the peak was located at or above 10 keV, making 1ES 2344+514 the second blazar (after MKN501) with the synchrotron peak in the hard X-ray band. The shift, and the corresponding increase in luminosity, might be due to the onset of a second synchrotron component extending from the soft to the hard X-ray band where most of the power is emitted. Rapid variability on a timescale of ...

  19. X-Ray Luminosity and Spectral Variability in the TEV BL Lac 1ES2344+514

    CERN Document Server

    Giommi, P; Perlman, E S

    1998-01-01

    The results of a series of five \\sax observations of the TeV BL Lac object 1ES2344+514 are briefly presented. Large amplitude luminosity variability, associated to impressive spectral changes in the hard X-rays, have been found. The shape of the lightcurve depends on energy, with the flare starting and ending in the hard band, but with maximum intensity possibly reached earlier in the soft X-rays. The luminosity and spectral changes may be due to a shift of the peak of the synchrotron emission from the soft X-rays to the hard X-ray band similar to that detected during \\sax observations of MKN 501.

  20. Intermediate Scale Structures in BL Lac objects

    CERN Document Server

    Reynolds, C; Gabuzda, D C

    2004-01-01

    The parsec-scale total intensity structures of BL Lac objects share many characteristics with quasars: e.g. well-collimated jets and superluminal motion. However, the jets of BL Lac objects appear to fade much more quickly than those in quasars and on VLA scales many BL Lacs have structures comparable to those of low luminosity (FR I) radio galaxies, in which kpc-scale flow speeds are non-relativistic. The region between parsec and kiloparsec scales is therefore one of transition in BL Lac objects. We have carried out VLBI observations of a small sample of BL Lac objects at frequencies between 2.3 GHz and 327 MHz in order to investigate this transition region. Preliminary results for two of these sources are presented here. Coherent structures are detected in these sources out to a distance of several tens of parsecs. We find evidence for significant changes in jet structure on scales of a few tens of milliarcseconds, both in terms of the orientation and collimation of the jets.

  1. Clustering environments of BL Lac objects

    Science.gov (United States)

    Wurtz, Ronald; Ellingson, Erica; Stocke, John T.; Yee, H. K. C.

    1993-01-01

    We report measurements of the amplitude of the BL Lac galaxy spatial covariance function, B(gb), for the fields of five BL Lacertae objects. We present evidence for rich clusters around MS 1207+39 and MS 1407+59, and confirm high richness for the cluster containing H0414+009. We discuss the ease of 3C 66 A and find evidence for a poor cluster based on an uncertain redshift of z = 0.444. These data suggest that at least some BL Lac objects are consistent with being FR 1 radio galaxies in rich clusters.

  2. Discovery of Very High-Energy Gamma-Ray Radiation from the BL Lac 1ES 0806+524

    CERN Document Server

    Aliu, E; Bautista, M; Beilicke, M; Benbow, W; Böttcher, M; Bradbury, S M; Buckley, J H; Bugaev, V; Butt, Y; Byrum, K; Cannon, A; Celik, O; Cesarini, A; Chow, Y C; Ciupik, L; Cogan, P; Colin, P; Cui, W; Dickherber, R; Duke, C; Ergin, T; Falcone, A; Fegan, S J; Finley, J P; Finnegan, G; Fortin, P; Fortson, L; Furniss, A; Gall, D; Gibbs, K; Gillanders, G H; Grube, J; Guenette, R; Gyuk, G; Hanna, D; Hays, E; Holder, J; Horan, D; Hui, C M; Humensky, T B; Imran, A; Kaaret, Philip; Karlsson, N; Kertzman, M; Kieda, D; Kildea, J; Konopelko, A; Krawczynski, H; Krennrich, F; Lang, M J; Le Bohec, S; Maier, G; McCann, A; McCutcheon, M; Millis, J; Moriarty, P; Mukherjee, R; Nagai, T; Ong, R A; Otte, A N; Pandel, D; Perkins, J S; Petry, D; Pohl, M; Quinn, J; Ragan, K; Reyes, L C; Reynolds, P T; Roache, E; Rose, J; Schroedter, M; Sembroski, G H; Smith, A W; Steele, D; Swordy, S P; Theiling, M; Toner, J A; Valcarcel, L; Varlotta, A; Vasilev, V V; Wagner, R G; Wakely, S P; Ward, J E; Weekes, T C; Weinstein, A; White, R J; Williams, D A; Wissel, S; Wood, M; Zitzer, B

    2008-01-01

    The high-frequency-peaked BL-Lacertae object \\objectname{1ES 0806+524}, at redshift z=0.138, was observed in the very-high-energy (VHE) gamma-ray regime by VERITAS between November 2006 and April 2008. These data encompass the two-, and three-telescope commissioning phases, as well as observations with the full four-telescope array. \\objectname{1ES 0806+524} is detected with a statistical significance of 6.3 standard deviations from 245 excess events. Little or no measurable variability on monthly time scales is found. The photon spectrum for the period November 2007 to April 2008 can be characterized by a power law with photon index $3.6 \\pm 1.0_{\\mathrm{stat}} \\pm 0.3_{\\mathrm{sys}}$ between $\\sim$300 GeV and $\\sim$700 GeV. The integral flux above 300 GeV is $(2.2\\pm0.5_{\\mathrm{stat}}\\pm0.4_{\\mathrm{sys}})\\times10^{-12}\\:\\mathrm{cm}^{2}\\:\\mathrm{s}^{-1}$ which corresponds to 1.8% of the Crab Nebula flux. Non contemporaneous multiwavelength observations are combined with the VHE data to produce a broadband ...

  3. Discovery of >350 GeV Gamma Rays from the BL Lacertae Object 1ES 2344+514

    CERN Document Server

    Catanese, M; Badran, H M; Biller, S D; Bond, I H; Boyle, P J; Bradbury, S M; Buckley, J H; Burdett, A M; Gordo, J B; Carter-Lewis, D A; Cawley, M F; Connaughton, V; Fegan, D J; Finley, J P; Gaidos, J A; Hall, T; Hillas, A M; Krennrich, F; Lamb, R C; Lessard, R W; Masterson, C; McEnery, J E; Mohanty, G B; Quinn, J; Rodgers, A J; Rose, H J; Samuelson, F W; Schubnell, M S; Sembroski, G H; Srinivasan, R; Weekes, T C; Wilson, C W; Zweerink, J A

    1997-01-01

    We present the discovery of >350 GeV gamma-ray emission from the BL Lacertae object 1ES 2344+514 with the Whipple Observatory 10m gamma-ray telescope. This is the third BL Lac object detected at gamma-ray energies above 300 Gev, the other two being Markarian 421 (Mrk 421) and Mrk501. These three active galactic nuclei are all X-ray selected and have the lowest known redshifts of any BL Lac objects currently identified. The evidence for emission derives primarily from an apparent flare on December 20, 1995 when a 6 sigma excess was detected with a flux approximately 63% of the very high energy gamma-ray emission from the Crab Nebula, the standard candle for TeV gamma-ray sources. Excluding the flare, observations between October 1995 and January 1996 yield a 4 sigma detection corresponding to 11% of the VHE Crab Nebula flux. Observations spanning September 1996 to January 1997 failed to yield a significant detection of a steady flux or any flaring. For this period, the 99.9% confidence level upper limit is <...

  4. Black hole masses of BL Lac objects

    OpenAIRE

    J. K. Kotilainen; Falomo, R.; Treves, A.

    2002-01-01

    The correlation between black hole mass M(BH) and the central stellar velocity dispersion sigma in nearby elliptical galaxies affords a novel way to determine M(BH) in active galaxies. We report on measurements of sigma from optical spectra of 7 BL Lac host galaxies. The range of sigma (160 - 290 km/s) corresponds to estimated M(BH) of 5 x 10^7 - 9 x 10^8 Mo. The average ratio of M(BH) to the host galaxy mass is 1.4 x 10^-3, consistent with that estimated in other active and inactive galaxies...

  5. Radio Detection of 18 RASS BL Lac Objects

    Directory of Open Access Journals (Sweden)

    Anderson M. W. B.

    2009-12-01

    Full Text Available We present the radio detection of 18 BL Lac objects from oursurvey of over 575 deg$^2$ of sky. These 18 objects are located within$20arcsec$ of the X-ray position, of which 11 have a measuredred-shift. All candidates are radio emitters above $sim$1 mJy and fall within the range of existing samples on the two colour, $alpha _mathrm{RO}$ vs $alpha _mathrm{OX}$, diagram with a transitional population of three evident. Two unusual sources have been identified, a candidate radio quiet BL Lac, RX J0140.9-4130, and an extreme HBL, RX J0109.9-4020, with $log( u _mathrm{peak}approx 19.2$. The BL Lac $log(N-log(S$ relation is consistent with other samples and indicates the ROSAT All Sky Survey (RASS could contain ($2000{pm}400$ BL Lac objects.

  6. Six-year Optical Monitoring of BL Lacertae Object 1ES 0806+52.4

    CERN Document Server

    Man, Zhongyi; Wu, Jianghua; Zhou, Xu; Yuan, Qirong

    2014-01-01

    We present the results of the first systematic long-term multi-color optical monitoring of the BL Lacertae object 1ES 0806+52.4. The monitoring was performed in multiple passbands with a 60/90 cm Schmidt telescope from December 2005 to February 2011. The overall brightness of this object decreased from 2005 December to 2008 December, and regained after that. A sharp outburst probably occurred around the end of our monitoring program. Overlapped on the long-term trend are some short-term small-amplitude oscillations. No intra-night variability was found in the object, which is in accord with the historical observations before 2005. By investigating the color behavior, we found strong bluer-when-brighter chromatism for the long-term variability of 1ES 0806+52.4. The total amplitudes at the c, i and o bands are 1.18, 1.12, and 1.02 mags, respectively. The amplitudes tend to increase toward shorter wavelength, which may be the major cause of bluer-when-brighter. Such bluer-when-brighter is also found in other bla...

  7. VERITAS and multiwavelength observations of the BL Lacertae object 1ES 1741+196

    Science.gov (United States)

    Abeysekara, A. U.; Archambault, S.; Archer, A.; Benbow, W.; Bird, R.; Biteau, J.; Buchovecky, M.; Buckley, J. H.; Bugaev, V.; Byrum, K.; Cardenzana, J. V.; Cerruti, M.; Chen, X.; Christiansen, J. L.; Ciupik, L.; Connolly, M. P.; Cui, W.; Dickinson, H. J.; Dumm, J.; Eisch, J. D.; Errando, M.; Falcone, A.; Feng, Q.; Finley, J. P.; Fleischhack, H.; Flinders, A.; Fortin, P.; Fortson, L.; Furniss, A.; Gillanders, G. H.; Griffin, S.; Grube, J.; Gyuk, G.; Huetten, M.; Hanna, D.; Holder, J.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kelley-Hoskins, N.; Kertzman, M.; Kieda, D.; Krause, M.; Krennrich, F.; Lang, M. J.; Maier, G.; McArthur, S.; McCann, A.; Meagher, K.; Moriarty, P.; Mukherjee, R.; Nieto, D.; O'Brien, S.; O'Faoláin de Bhróithe, A.; Ong, R. A.; Otte, A. N.; Park, N.; Pelassa, V.; Petrashyk, A.; Petry, D.; Pohl, M.; Popkow, A.; Pueschel, E.; Quinn, J.; Ragan, K.; Ratliff, G.; Reyes, L. C.; Reynolds, P. T.; Reynolds, K.; Richards, G. T.; Roache, E.; Rulten, C.; Santander, M.; Sembroski, G. H.; Shahinyan, K.; Smith, A. W.; Staszak, D.; Telezhinsky, I.; Tucci, J. V.; Tyler, J.; Vincent, S.; Wakely, S. P.; Weiner, O. M.; Weinstein, A.; Wilhelm, A.; Williams, D. A.; Zitzer, B.

    2016-07-01

    We present results from multiwavelength observations of the BL Lacertae object 1ES 1741 + 196, including results in the very high energy γ-ray regime using the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The VERITAS time-averaged spectrum, measured above 180 GeV, is well modelled by a power law with a spectral index of 2.7 ± 0.7stat ± 0.2syst. The integral flux above 180 GeV is (3.9 ± 0.8stat ± 1.0syst) × 10-8 m-2 s-1, corresponding to 1.6 per cent of the Crab nebula flux on average. The multiwavelength spectral energy distribution of the source suggests that 1ES 1741+196 is an extreme-high-frequency-peaked BL Lacertae object. The observations analysed in this paper extend over a period of six years, during which time no strong flares were observed in any band. This analysis is therefore one of the few characterizations of a blazar in a non-flaring state.

  8. VERITAS and Multiwavelength Observations of the BL Lacertae Object 1ES 1741+196

    CERN Document Server

    Abeysekara, A U; Archer, A; Benbow, W; Bird, R; Biteau, J; Buchovecky, M; Buckley, J H; Bugaev, V; Byrum, K; Cardenzana, J V; Cerruti, M; Chen, X; Christiansen, J L; Ciupik, L; Connolly, M P; Cui, W; Dickinson, H J; Dumm, J; Eisch, J D; Errando, M; Falcone, A; Feng, Q; Finley, J P; Fleischhack, H; Flinders, A; Fortin, P; Fortson, L; Furniss, A; Gillanders, G H; Griffin, S; Grube, J; Gyuk, G; Hütten, M; Hanna, D; Holder, J; Humensky, T B; Johnson, C A; Kaaret, P; Kar, P; Kelley-Hoskins, N; Kertzman, M; Kieda, D; Krause, M; Krennrich, F; Kumar, S; Lang, M J; Maier, G; McArthur, S; McCann, A; Meagher, K; Moriarty, P; Mukherjee, R; Nieto, D; O'Brien, S; de Bhróithe, A O'Faoláin; Ong, R A; Otte, A N; Park, N; Pelassa, V; Petrashyk, A; Pohl, M; Popkow, A; Pueschel, E; Quinn, J; Ragan, K; Ratliff, G; Reyes, L C; Reynolds, P T; Richards, G T; Roache, E; Rulten, C; Santander, M; Sembroski, G H; Shahinyan, K; Smith, A W; Staszak, D; Telezhinsky, I; Tucci, J V; Tyler, J; Vincent, S; Wakely, S P; Weiner, O M; Weinstein, A; Wilhelm, A; Williams, D A; Zitzer, B

    2016-01-01

    We present results from multiwavelength observations of the BL Lacertae object 1ES 1741+196, including results in the very-high-energy $\\gamma$-ray regime using the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The VERITAS time-averaged spectrum, measured above 180 GeV, is well-modelled by a power law with a spectral index of $2.7\\pm0.7_{\\mathrm{stat}}\\pm0.2_{\\mathrm{syst}}$. The integral flux above 180 GeV is $(3.9\\pm0.8_{\\mathrm{stat}}\\pm1.0_{\\mathrm{syst}})\\times 10^{-8}$ m$^{-2}$ s$^{-1}$, corresponding to 1.6% of the Crab Nebula flux on average. The multiwavelength spectral energy distribution of the source suggests that 1ES 1741+196 is an extreme-high-frequency-peaked BL Lacertae object. The observations analysed in this paper extend over a period of six years, during which time no strong flares were observed in any band. This analysis is therefore one of the few characterizations of a blazar in a non-flaring state.

  9. Understanding BL Lac objects Structural & kinematic mode changes in the BL Lac object PKS 0735+178

    CERN Document Server

    Britzen, S; Gong, B P; Zhang, J W; Gopal-Krishna,; Goyal, Arti; Aller, M F; Aller, H D; Zensus, J A

    2010-01-01

    Context. We present evidence that parsec-scale jets in BL Lac objects may be significantly distinct in kinematics from their counterparts in quasars. We argued this previously for the BL lac sources 1803+784 and 0716+714, report here a similar pattern for another well-known BL Lac object, PKS 0735+178, whose nuclear jet is found to exhibit kinematics atypical of quasars. Aims. A detailed study of the jet components' motion reveals that the standard AGN paradigm of apparent superluminal motion does not always describe the kinematics in BL Lac objects. We study 0735+178 here to augment and improve the understanding of the peculiar motions in the jets of BL Lac objects as a class. Methods. We analyzed 15 GHz VLBA (Very Long Baseline Array) observations (2cm/MOJAVE survey) performed at 23 epochs between 1995.27 and 2008.91. Results. We found a drastic structural mode change in the VLBI jet of 0735+178, between 2000.4 and 2001.8 when its twice sharply bent trajectory turned into a linear shape.We further found tha...

  10. Discovery of hard-spectrum γ-ray emission from the BL Lacertae object 1ES 0414+009

    Science.gov (United States)

    H.E.S.S. Collaboration; Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Balzer, A.; Barnacka, A.; Barres de Almeida, U.; Becherini, Y.; Becker, J.; Behera, B.; Bernloehr, K.; Birsin, E.; Biteau, J.; Bochow, A.; Boisson, C.; Bolmont, J.; Bordas, P.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Buesching, I.; Carrigan, S.; Casanova, S.; Cerruti, M.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Chounet, L.-M.; Clapson, A. C.; Coignet, G.; Cologna, G.; Conrad, J.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; Dickinson, H. J.; Djannati-Ataie, A.; Domainko, W.; Drury, L. O'c.; Dubois, F.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Espigat, P.; Fallon, L.; Farnier, C.; Feinstein, F.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Foerster, A.; Fuesling, M.; Gallant, Y. A.; Gast, H.; Gerard, L.; Gerbig, D.; Giebels, B.; Glicenstein, J. F.; Glueck, B.; Goret, P.; Goering, D.; Haeffner, S.; Hague, J. D.; Hampf, D.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hoffmann, A.; Hofmann, W.; Hofverberg, P.; Holler, M.; Horns, D.; Jacholkowska, A.; de Jager, O. C.; Jahn, C.; Jamrozy, M.; Jung, I.; Kastendieck, M. A.; Katarzynski, K.; Katz, U.; Kaufmann, S.; Keogh, D.; Khangulyan, D.; Khelifi, B.; Klochkov, D.; Kluzniak, W.; Kneiske, T.; Komin, Nu.; Kosack, K.; Kossakowski, R.; Laffon, H.; Lamanna, G.; Lennarz, D.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Masbou, J.; Maurin, D.; Maxted, N.; Mayer, M.; McComb, T. J. L.; Medina, M. C.; Mehault, J.; Moderski, R.; Moulin, E.; Naumann, C. L.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Nguyen, N.; Nicholas, B.; Niemiec, J.; Nolan, S. J.; Ohm, S.; de Ona Wilhelmi, E.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Paz Arribas, M.; Pedaletti, G.; Pelletier, G.; Petrucci, P.-O.; Pita, S.; Puehlhofer, G.; Punch, M.; Quirrenbach, A.; Raue, M.; Rayner, S. M.; Reimer, A.; Reimer, O.; Renaud, M.; de Los Reyes, R.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Ruppel, J.; Sahakian, V.; Sanchez, D. A.; Santangelo, A.; Schlickeiser, R.; Schoeck, F. M.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Sheidaei, F.; Sikora, M.; Skilton, J. L.; Sol, H.; Spengler, G.; Stawarz, L.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Szostek, A.; Tavernet, J.-P.; Terrier, R.; Tluczykont, M.; Valerius, K.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Vialle, J. P.; Viana, A.; Vincent, P.; Voelk, H. J.; Volpe, F.; Vorobiov, S.; Vorster, M.; Wagner, S. J.; Ward, M.; White, R.; Wierzcholska, A.; Zacharias, M.; Zajczyk, A.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S. L.; Costamante, L.; Fegan, S.; Ajello, M.

    2012-02-01

    Context. 1ES 0414 + 009 (z = 0.287) is a distant high-frequency-peaked BL Lac object, and has long been considered a likely emitter of very-high-energy (VHE, E > 100 GeV) γ-rays due to its high X-ray and radio flux. Aims: Observations in the VHE γ-ray band and across the electromagnetic spectrum can provide insights into the origin of highly energetic particles present in the source and the radiation processes at work. Because of the distance of the source, the γ-ray spectrum might provide further limits on the level of the extragalactic background light (EBL). Methods: We report observations made between October 2005 and December 2009 with H.E.S.S., an array of four imaging atmospheric Cherenkov telescopes. Observations at high energies (HE, 100 MeV-100 GeV) with the Fermi-LAT instrument in the first 20 months of its operation are also reported. To complete the multi-wavelength picture, archival UV and X-ray observations with the Swift satellite and optical observations with the ATOM telescope are also used. Results: Based on the observations with H.E.S.S., 1ES 0414 + 009 is detected for the first time in the VHE band. An excess of 224 events is measured, corresponding to a significance of 7.8σ. The photon spectrum of the source is well described by a power law, with photon index of ΓVHE = 3.45 ± 0.25stat ± 0.20syst. The integral flux above 200 GeV is (1.88 ± 0.20stat ± 0.38syst) × 10-12 cm-2 s-1. Observations with the Fermi-LAT in the first 20 months of operation show a flux between 200 MeV and 100 GeV of (2.3 ± 0.2stat) × 10-9 erg cm-2 s-1, and a spectrum well described by a power-law function with a photon index ΓHE = 1.85 ± 0.18. Swift/XRT observations show an X-ray flux between 2 and 10 keV of (0.8-1) × 10-11 erg cm-2 s-1, and a steep spectrum ΓX = (2.2-2.3). Combining X-ray with optical-UV data, a fit with a log-parabolic function locates the synchrotron peak around 0.1 keV. Conclusions: Although the GeV-TeV observations do not provide better

  11. VLBI observations of seven BL Lac objects from RGB sample

    CERN Document Server

    Wu, Zhongzu; Gu, Minfeng; Liu, Yi

    2007-01-01

    We present EVN observations of seven BL Lac objects selected from the RGB sample. To investigate the intrinsic radiation property of BL Lac objects, we estimated the Doppler factor with the VLA or MERLIN core and the total 408 MHz luminosity for a sample of 170 BL Lac objects. The intrinsic (comoving) synchrotron peak frequency was then calculated by using the estimated Doppler factor. Assuming a Lorentz factor of 5, the viewing angle of jets was constrained. The high-resolution VLBI images of seven sources all show a core-jet structure. We estimated the proper motions of three sources with the VLBI archive data, and find that the apparent speed increases with the distance of components to the core for all of them. In our BL Lacs sample, the Doppler factor of LBLs is systematically larger than that of IBLs and HBLs. We find a significant anti-correlation between the total 408 MHz luminosity and the intrinsic synchrotron peak frequency. However, the scatter is much larger than for the blazar sequence. Moreover...

  12. Radio-weak BL Lac Objects in the Fermi Era

    Science.gov (United States)

    Massaro, F.; Marchesini, E. J.; D’Abrusco, R.; Masetti, N.; Andruchow, I.; Smith, Howard A.

    2017-01-01

    The existence of “radio-weak BL Lac objects” (RWBLs) has been an open question, and has remained unsolved since the discovery that quasars could be radio-quiet or radio-loud. Recently, several groups identified RWBL candidates, mostly found while searching for low-energy counterparts of the unidentified or unassociated gamma-ray sources listed in the Fermi catalogs. Confirming RWBLs is a challenging task since they could be confused with white dwarfs (WDs) or weak emission line quasars (WELQs) when there are not sufficient data to precisely draw their broadband spectral energy distribution, and their classification is mainly based on a featureless optical spectra. Motivated by the recent discovery that Fermi BL Lacs appear to have very peculiar mid-IR emission, we show that it is possible to distinguish between WDs, WELQs, and BL Lacs using the [3.4]–[4.6]–[12] μm color–color plot built using the WISE magnitudes when the optical spectrum is available. On the basis of this analysis, we identify WISE J064459.38+603131 and WISE J141046.00+740511.2 as the first two genuine RWBLs, both potentially associated with Fermi sources. Finally, to strengthen our identification of these objects as true RWBLs, we present multifrequency observations for these two candidates to show that their spectral behavior is indeed consistent with that of the BL Lac population.

  13. Optical polarization of high-energy BL Lac objects

    CERN Document Server

    Hovatta, T; Blinov, D; Pavlidou, V; Nilsson, K; Kiehlmann, S; Angelakis, E; Ramazani, V Fallah; Liodakis, I; Myserlis, I; Panopoulou, G V; Pursimo, T

    2016-01-01

    We investigate the optical polarization properties of high-energy BL Lac objects using data from the RoboPol blazar monitoring program and the Nordic Optical Telescope. We wish to understand if there are differences in the BL Lac objects that are detected with the current-generation TeV instruments compared to those that have not yet been detected. The mean polarization fraction of the TeV-detected BL Lacs is 5% while the non-TeV sources show a higher mean polarization fraction of 7%. This difference in polarization fraction disappears when the dilution by the unpolarized light of the host galaxy is accounted for. The TeV sources show somewhat lower fractional polarization variability amplitudes than the non-TeV sources. Also the fraction of sources with a smaller spread in the Q/I - U/I -plane and a clumped distribution of points away from the origin, possibly indicating a preferred polarization angle, is larger in the TeV than in the non-TeV sources. These differences between TeV and non-TeV samples seems t...

  14. "Oscillating" components in the BL Lac object 0716+714?

    CERN Document Server

    Britzen, S; Witzel, A; Agudo, I; Aller, M F; Aller, H D; Eckart, A; Zensus, J A

    2006-01-01

    15 VLBA observations of the BL Lac object 0716+714, performed between 1994.67 and 2006.40 at 15 GHz, have been analyzed. Part of the data (12 epochs) were obtained within the Mojave-survey project and reanalyzed by us. We present a new motion scenario for jet model component motion in this source which suggests that no longterm-outward motion but rather an oscillation of components around an average core separation is taking place. Although no significant outward motion in the core separation can be found, motion with regard to the position angle is observed. We give lower limits for the derived apparent motions and Doppler factors and compare them with values published in the literature. We find a relation between the total flux-density evolution at 14.5 GHz (UMRAO data) and the position angle changes observed for the jet component closest to the core. We suggest a significant geometric contribution to the longterm flux-density variability in 0716+714.

  15. Systematic search for VHE gamma-ray emission from X-ray bright high-frequency BL Lac objects

    CERN Document Server

    Albert, J

    2007-01-01

    Motivated by the fact that all but two (M87, BL Lac) extragalactic sources detected so far at VHE energies belong to the so-called HBL class of high-frequency peaked BL Lac objects, a systematic scan of the compilation of X-ray blazars by Donato et al. (2001) has been performed using the MAGIC telescope. The observations took place from December 2004 to March 2006 and cover sources on the northern sky visible under small zenith distances zd 2uJy) sources emitting at least the same energy flux at 200GeV as at 1keV. In order to avoid strong gamma-ray attenuation close to the energy threshold, the redshift of the sources was constrained to values z < 0.3. Of the 14 sources observed, 1ES 1218+30.4 (for the first time at very high energies) and 1ES 2344+51.4 (strong detection in a low flux state) have been detected in addition to the known bright TeV blazars Mrk 421 and Mrk 501. For the remaining sources, we present here the 99% confidence level upper limits on the integral flux above ~200GeV. A marginal exces...

  16. BeppoSAX Observations of Unprecedented Synchrotron Activity in the BL Lac Object Mkn 501

    CERN Document Server

    Pian, E; Tagliaferri, G; Ghisellini, G; Maraschi, L; Treves, A; Urry, C M; Fiore, F; Giommi, P; Palazzi, E; Chiappetti, L; Sambruna, R M; Pian, Elena; Vacanti, Giuseppe; Tagliaferri, Gianpiero; Ghisellini, Gabriele; Maraschi, Laura; Treves, Aldo; Fiore, Fabrizio; Giommi, Paolo; Palazzi, Eliana; Chiappetti, Lucio; Sambruna, Rita M.

    1997-01-01

    The BL Lac object Mkn 501, one of the only three extragalactic sources (with Mkn 421 and 1ES 2344+514) so far detected at TeV energies, was observed with the BeppoSAX satellite on 7, 11, and 16 April 1997 during a phase of high activity at TeV energies, as monitored with the Whipple, HEGRA and CAT Cherenkov telescopes. Over the whole 0.1-200 keV range the spectrum was exceptionally hard (alpha =< 1, with F_nu ~ nu^{-alpha}) indicating that the X-ray power output peaked at (or above) ~100 keV. This represents a shift of at least two orders of magnitude with respect to previous observations of Mkn 501, a behavior never seen before in this or any other blazar. The overall X-ray spectrum hardens with increasing intensity and, at each epoch, it is softer at larger energies. The correlated variability from soft X-rays to the TeV band points to models in which the same population of relativistic electrons produces the X-ray continuum via synchrotron radiation and the TeV emission by inverse Compton scattering of ...

  17. Gamma-ray Emission from the γ-ray-loud BL Lac Objects

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Using the HST observation data of BL Lac objects by Urry et al. and γγ-ray observation data, we find that there is a correlation between Fγ and FO nucleifor γ-ray-loud BL Lac objects (correlation coefficients: γ = 0.63,p = 4.0 × 10-2),but no correlation between Fγ and Fohost, where FO nuclei and Fohost are the fluxes ofnuclei and host galaxy in V-band. For 19 γ-ray-loud BL Lac objects with observedspectral index in multi-wavebands, the spectral index correlations between any twobands are as follow: (1) there is a strong correlation between αγ and αK for 15 BLLac objects(γ = 0.84,p = 3.11 × 10-4); (2) the correlation between αγ and αo for12 BL Lac objects is γ = 0.82,p = 1.5 × 10-3; (3) there is no correlation betweenαγ and αx for 16 BL Lac objects. The results, together with characteristic double-humped shape of their SEDs, show that the synchrotron self-Compton mechanismmight be a main mechanism for the γ-ray emission of the BL Lac objects. Theelectrons emitting IR and optical radiation via synchrotron are also responsible forupscattering these photons to γ-rays, and a variability in IR-optical regime shouldbe accompanied by a change in the γ-rays.

  18. Comparison between TeV and non-TeV BL Lac Objects

    CERN Document Server

    Lin, C

    2016-01-01

    BL Lacertae objects (BL Lacs) is the dominant population of TeV emitting blazars. In this work, we investigate whether there is any special observational properties for TeV sources. To do so, we will compare the observational properties of TeV detected BL Lacs (TeV BLs) and non-TeV detected BL Lac objects (non-TeV BLs). From the 3rd $Fermi$/LAT catalog (3FGL), we can get 662 BL Lacs, out of which, 47 are TeV BLs and 615 are non-TeV BLs. Their multi-wavelength flux densities ($F_{\\rm R}$, $F_{\\rm O}$, $F_{\\rm X}$, $F_{\\gamma}$), photon spectral indexes ($\\alpha_{\\rm X}^{\\rm ph}$, $\\alpha_{\\gamma}^{\\rm ph}$), and effective spectral indexes ($\\alpha_{\\rm RO}$ and $\\alpha_{\\rm OX}$) are compiled from the available literatures. Then the luminosities ($\\log\\,{\

  19. The host galaxies of BL Lac objects in the near-infrared

    CERN Document Server

    Kotilainen, J K; Scarpa, R

    1998-01-01

    We present the results of near-infrared H band (1.65 microns) imaging of 11 BL Lac objects with redshifts ranging from z = 0.05 to 0.9. We are able to clearly detect the host galaxy in seven low redshift (z<=0.24) BL Lacs, while the four unresolved BL Lacs have either high or unknown redshift. The galaxies hosting the low redshift BL Lacs are large (average bulge scale length R(e) = 8.8+-9.9 kpc) and luminous (average M(H) = -25.8+-0.5), i.e. slightly brighter than the typical galaxy luminosity L* (M*(H) = -25.0+-0.2), and of similar luminosity to or slightly fainter than brightest cluster galaxies (M(H) = -26.3+-0.3). The average optical/near-infrared colour and colour gradient of the BL Lac hosts (R-H = 2.2+-0.5; d(R-H)/d(log r) = -0.09$+-0.04) are consistent with the hosts being normal ellipticals, indicating that the nuclear activity has only a marginal effect on the star formation history and other properties of the hosts. The BL Lac hosts appear slightly less luminous than those of higher redshift fl...

  20. The physical properties of \\textit{Fermi} TeV BL Lac objects jets

    CERN Document Server

    Ding, N; Xiong, D R; Zhang, H J

    2016-01-01

    We investigate the physical properties of \\textit{Fermi} TeV BL Lac objects jets by modeling the quasi-simultaneous spectral energy distribution of 29 \\textit{Fermi} TeV BL Lacs in the frame of a one-zone leptonic synchrotron self-Compton model. Our main results are the following: (i) There is a negative correlation between $B$ and $\\delta$ in our sample, which suggests that $B$ and $\\delta$ are dependent on each other mainly in Thomson regime. (ii) There are negative correlations between $\

  1. Dynamical Black Hole Masses of BL Lac Objects from the Sloan Digital Sky Survey

    NARCIS (Netherlands)

    Plotkin, Richard M.; Markoff, Sera; Trager, Scott C.; Anderson, Scott F.

    2012-01-01

    We measure black hole masses for 71 BL Lac objects from the Sloan Digital Sky Survey (SDSS) with redshifts out to z ∼ 0.4. We perform spectral decompositions of their nuclei from their host galaxies and measure their stellar velocity dispersions. Black hole masses are then derived from the black

  2. Dynamical black hole masses of BL Lac objects from the Sloan Digital Sky Survey

    NARCIS (Netherlands)

    Plotkin, R. M.; Markoff, S.; Trager, S. C.; Anderson, S. F.

    We measure black hole masses for 71 BL Lac objects from the Sloan Digital Sky Survey with redshifts out to z˜ 0.4. We perform spectral decompositions of their nuclei from their host galaxies and measure their stellar velocity dispersions. Black hole masses are then derived from the black hole mass -

  3. Dynamical black hole masses of BL Lac objects from the Sloan Digital Sky Survey

    NARCIS (Netherlands)

    Plotkin, R.M.; Markoff, S.; Trager, S.C.; Anderson, S.F.

    2011-01-01

    We measure black hole masses for 71 BL Lac objects from the Sloan Digital Sky Survey with redshifts out to z∼ 0.4. We perform spectral decompositions of their nuclei from their host galaxies and measure their stellar velocity dispersions. Black hole masses are then derived from the black hole mass -

  4. Dynamical Black Hole Masses of BL Lac Objects from the Sloan Digital Sky Survey

    NARCIS (Netherlands)

    Plotkin, Richard M.; Markoff, Sera; Trager, Scott C.; Anderson, Scott F.

    2012-01-01

    We measure black hole masses for 71 BL Lac objects from the Sloan Digital Sky Survey (SDSS) with redshifts out to z ∼ 0.4. We perform spectral decompositions of their nuclei from their host galaxies and measure their stellar velocity dispersions. Black hole masses are then derived from the black hol

  5. Dynamical black hole masses of BL Lac objects from the Sloan Digital Sky Survey

    NARCIS (Netherlands)

    Plotkin, R.M.; Markoff, S.; Trager, S.C.; Anderson, S.F.

    2011-01-01

    We measure black hole masses for 71 BL Lac objects from the Sloan Digital Sky Survey with redshifts out to z∼ 0.4. We perform spectral decompositions of their nuclei from their host galaxies and measure their stellar velocity dispersions. Black hole masses are then derived from the black hole mass -

  6. Dynamical black hole masses of BL Lac objects from the Sloan Digital Sky Survey

    NARCIS (Netherlands)

    Plotkin, R. M.; Markoff, S.; Trager, S. C.; Anderson, S. F.

    2011-01-01

    We measure black hole masses for 71 BL Lac objects from the Sloan Digital Sky Survey with redshifts out to z˜ 0.4. We perform spectral decompositions of their nuclei from their host galaxies and measure their stellar velocity dispersions. Black hole masses are then derived from the black hole mass -

  7. Dynamical black hole masses of BL Lac objects from the Sloan Digital Sky Survey

    NARCIS (Netherlands)

    Plotkin, R. M.; Markoff, S.; Trager, S. C.; Anderson, S. F.

    2011-01-01

    We measure black hole masses for 71 BL Lac objects from the Sloan Digital Sky Survey with redshifts out to z similar to 0.4. We perform spectral decompositions of their nuclei from their host galaxies and measure their stellar velocity dispersions. Black hole masses are then derived from the black h

  8. STACEE Observations of 1ES 1218+304

    CERN Document Server

    Mukherjee, R; Ball, J; Carson, J E; Covault, C E; Driscoll, D D; Fortin, P; Gingrich, D M; Hanna, D S; Jarvis, A; Kildea, J; Lindner, T; Müller, C; Ong, R A; Ragan, K; Williams, D A; Zweerink, J

    2007-01-01

    We present the analysis and results of recent high-energy gamma-ray observations of the high energy-peaked BL Lac (HBL) object 1ES 1218+304 with the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE). 1ES 1218+304 is an X-ray bright HBL at a redshift z=0.182. It has been predicted to be a gamma-ray emitter above 100 GeV, detectable by ground-based Cherenkov telescopes. Recently this source has been detected by MAGIC and VERITAS, confirming these predictions. STACEE's sensitivity to astrophysical sources at energies above 100 GeV allows it to explore high energy sources such as X-ray bright active galaxies and gamma-ray bursts. We present results from STACEE observations of 1ES 1218+304 in the 2006 and 2007 observing seasons.

  9. Very high energy observations of the BL Lac objects 3C 66A and OJ 287

    CERN Document Server

    Lindner, T; Kildea, J; Ball, J; Bramel, D A; Carson, J; Covault, C E; Driscoll, D; Fortin, P; Gingrich, D M; Jarvis, A; Müller, C; Mukherjee, R; Ong, R A; Ragan, K; Scalzo, R A; Williams, D A; Zweerink, J

    2007-01-01

    Using the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE), we have observed the BL Lac objects 3C 66A and OJ 287. These are members of the class of low-frequency-peaked BL Lac objects (LBLs) and are two of the three LBLs predicted by Costamante and Ghisellini to be potential sources of very high energy (>100 GeV) gamma-ray emission. The third candidate, BL Lacertae, has recently been detected by the MAGIC collaboration. Our observations have not produced detections; we calculate a 99% CL upper limit of flux from 3C 66A of 0.15 Crab flux units and from OJ 287 our limit is 0.52 Crab. These limits assume a Crab-like energy spectrum with an effective energy threshold of 185 GeV.

  10. SPECTRAL VARIABILITY AND TRANSIENT INJECTION OF RELATIVISTIC ELECTRONS FOR BL LAC OBJECTS

    Institute of Scientific and Technical Information of China (English)

    MEI DONG-CHENG; XIE GUANG-ZHONG; CHEN LUO-EN

    2000-01-01

    The spectral hardening with increasing intensity in optical range for four BL Lac objects have been found by analyzing our observed data. Making use of the synchrotron loss of transient injection of relativistic electrons, we succeeded in explaining the phenomenon of the spectral hardening in the outburst phase. The value of magnetic intensity and the limit condition of the transient injection of relativistic electrons seem to be reasonable.

  11. VLBA Observations of Low Luminosity Flat Spectrum Radio Galaxies and BL Lac Objects: Polarisation Properties

    Science.gov (United States)

    Bondi, M.; Dallacasa, D.; Stanghellini, C.; Marchã, M. J. M.

    We obtained two-epoch VLBA observations at 5 GHz of a list of radio galaxies drawn from the 200 mJy sample (Marcha et al. 1996). The objects selected for milli-arcsecond scale observations are classified, on the basis of their optical spectroscopic and polarimetric properties, as BL Lac objects, normal weak line radio galaxies, broad line radio galaxies, and transition objects (those with intermediate properties). We present preliminary results on the radio polarization properties, on the milli-arcsecond scale, of objects with different optical properties and discuss structural variations detected from the two epochs.

  12. Unifying models for X-ray selected and Radio selected BL Lac Objects

    CERN Document Server

    Fossati, G; Ghisellini, G; Maraschi, L; Brera-Merate, O A

    1997-01-01

    We discuss alternative interpretations of the differences in the Spectral Energy Distributions (SEDs) of BL Lacs found in complete Radio or X-ray surveys. A large body of observations in different bands suggests that the SEDs of BL Lac objects appearing in X-ray surveys differ from those appearing in radio surveys mainly in having a (synchrotron) spectral cut-off (or break) at much higher frequency. In order to explain the different properties of radio and X-ray selected BL Lacs Giommi and Padovani proposed a model based on a common radio luminosity function. At each radio luminosity, objects with high frequency spectral cut-offs are assumed to be a minority. Nevertheless they dominate the X-ray selected population due to the larger X-ray-to-radio-flux ratio. An alternative model explored here (reminiscent of the orientation models previously proposed) is that the X-ray luminosity function is "primary" and that at each X-ray luminosity a minority of objects has larger radio-to-X-ray flux ratio. The prediction...

  13. Structured Jets in BL Lac Objects: Efficient PeV Neutrino Factories?

    Science.gov (United States)

    Tavecchio, Fabrizio; Ghisellini, Gabriele; Guetta, Dafne

    2014-09-01

    The origin of high-energy neutrinos (0.1-1 PeV range) detected by IceCube remains a mystery. In this work, we explore the possibility that efficient neutrino production can occur in structured jets of BL Lac objects, characterized by a fast inner spine surrounded by a slower layer. This scenario has been widely discussed in the framework of the high-energy emission models for BL Lac objects and radio galaxies. One of the relevant consequences of a velocity structure is the enhancement of the inverse Compton emission caused by the radiative coupling of the two zones. We show that a similar boosting could occur for the neutrino output of the spine through the photo-meson reaction of high-energy protons scattering off the amplified soft target photon field of the layer. Assuming the local density and the cosmological evolution of γ-ray BL Lac object derived from Fermi Large Area Telescope data, we calculate the expected diffuse neutrino intensity, which can match the IceCube data for a reasonable choice of parameters.

  14. STRUCTURED JETS IN BL LAC OBJECTS: EFFICIENT PeV NEUTRINO FACTORIES?

    Energy Technology Data Exchange (ETDEWEB)

    Tavecchio, Fabrizio; Ghisellini, Gabriele [INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate (Italy); Guetta, Dafne [INAF-Osservatorio astronomico di Roma, via Frascati 33, I-00040 Monte Porzio Catone (Italy)

    2014-09-20

    The origin of high-energy neutrinos (0.1–1 PeV range) detected by IceCube remains a mystery. In this work, we explore the possibility that efficient neutrino production can occur in structured jets of BL Lac objects, characterized by a fast inner spine surrounded by a slower layer. This scenario has been widely discussed in the framework of the high-energy emission models for BL Lac objects and radio galaxies. One of the relevant consequences of a velocity structure is the enhancement of the inverse Compton emission caused by the radiative coupling of the two zones. We show that a similar boosting could occur for the neutrino output of the spine through the photo-meson reaction of high-energy protons scattering off the amplified soft target photon field of the layer. Assuming the local density and the cosmological evolution of γ-ray BL Lac object derived from Fermi Large Area Telescope data, we calculate the expected diffuse neutrino intensity, which can match the IceCube data for a reasonable choice of parameters.

  15. Structured jets in BL Lac objects: efficient PeV neutrino factories?

    CERN Document Server

    Tavecchio, F; Guetta, D

    2014-01-01

    The origin of the high-energy neutrinos (0.1$-$1 PeV range) detected by IceCube remains a mystery. In this work we explore the possibility that efficient neutrino production can occur in structured jets of BL Lac objects, characterized by a fast inner spine surrounded by a slower layer. This scenario has been widely discussed in the framework of the high-energy emission models for BL Lacs and radiogalaxies. One of the relevant consequences of a velocity structure is the enhancement of the inverse Compton emission caused by the radiative coupling of the two zones. We show that a similar boosting could occur for the neutrino output of the spine through the photo-meson reaction of high-energy protons scattering off the amplified soft target photon field of the layer. Assuming the local density and the cosmological evolution of $\\gamma$-ray BL Lac derived from {\\it Fermi}-LAT data, we calculate the expected diffuse neutrino intensity, that can match the IceCube data for a reasonable choice of the parameters.

  16. VSOP monitoring of the compact BL Lac object AO 0235+164

    CERN Document Server

    Frey, S; Gabuzda, D C; Salter, C J; Altschüler, D R; Perillat, P; Aller, M F; Aller, H D; Hirabayashi, H; Davis, M M

    2005-01-01

    In 1999, the highly compact and variable BL Lac object AO 0235+164 was identified as the highest brightness temperature active galactic nucleus observed with the VLBI Space Observatory Programme (VSOP), with T_B > 5.8 x 10^{13} K. The sub-milliarcsecond radio structure of this source has been studied with dual-frequency (1.6 and 5 GHz), polarization-sensitive VSOP observations during 2001 and 2002. Here we present the results of this monitoring campaign. At the time of these observations, the source was weakly polarized and characterized by a radio core that is clearly resolved on space-ground baselines.

  17. Modelling the IDV Emissions of the BL Lac Objects with a Langevin Type Stochastic Differential Equation

    Indian Academy of Sciences (India)

    C. S. Leung; J. Y. Wei; T. Harko; Z. Kovacs

    2011-03-01

    In this paper, we introduce a simplified model for explaining the observations of optical intra-day variability (IDV) of the BL Lac Objects. We assume that the source of the IDV are the stochastic oscillations of an accretion disk around a supermassive black hole. The stochastic fluctuations on the vertical direction of the accretion disk are described by using a Langevin type equation with a damping term and a random, white noise type force. Furthermore, preliminary numerical simulation results are presented, which are based on the numerical analysis of the Langevin stochastic differential equation.

  18. Fermi LAT Detection of a Gamma-ray Flare from the BL Lac Object ON 246

    Science.gov (United States)

    Becerra, Josefa

    2015-06-01

    The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope has observed increasing gamma-ray flux from a source positionally consistent with the BL Lac object ON 246 (RA=187.55871 deg, Dec=25.30198 deg, J2000, Beasley et al. 2002, ApJS, 141, 13; with redshift z=0.135, Nass et al. 1996, A&A, 309, 419), also known as S3 1227+25 and 3FGL J1230.3+2519 (3FGL; Acero et al. 2015, arXiv:1501.02003).

  19. The long-term optical behavior of BL Lac object S5 0716+714

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    BL Lac object S5 0716+714 is a well-studied object.In this paper,the available optical(BVRI) data of this source are compiled,and the B-,V-,R-and I-band light curves are constructed.Each of them is analyzed by means of the discrete correlation function(DCF) method,the structure function(SF) method and the z-transformed discrete correlation function(ZDCF) method.The results imply that there is a possible periodic variation of 1211 days in each passband light curve.The source varies violently and complicatedly,and exhibits a brightening trend in the light curves.

  20. Analysis of Optical Variations of BL Lac Object AO 0235+164

    Indian Academy of Sciences (India)

    Wang Hong-tao

    2014-03-01

    Historical optical BVRI band data are combined on the BL Lac object AO 0235 + 164. In order to examine the possible existence of lags and correlations between variations in different optical bands from this source, a statistical analysis is performed through the Discrete Correlation Function (DCF) method. Monte Carlo simulations called Flux Redistribution/Random Subset Selection (FR/RSS) are performed to obtain statistically meaningful values for the cross-correlation time lags and their related uncertainties. The analysis confirms that the variations in different optical light curves are strongly correlated, with no or very weak lag within the errors. Long term variability of color indices are also analysed. No color variabilities are found.

  1. Optical and Radio variability of the Northern VHE gamma-ray emitting BL Lac objects

    CERN Document Server

    Lindfors, E J; Nilsson, K; Reinthal, R; Ramazani, V Fallah; Pavlidou, V; Max-Moerbeck, W; Richards, J; Berdyugin, A; Takalo, L; Sillanpää, A; Readhead, A C S

    2016-01-01

    We compare the variability properties of very high energy gamma-ray emitting BL Lac objects in the optical and radio bands. We use the variability information to distinguish multiple emission components in the jet, to be used as a guidance for spectral energy distribution modelling. Our sample includes 32 objects in the Northern sky that have data for at least 2 years in both bands. We use optical R-band data from the Tuorla blazar monitoring program and 15 GHz radio data from the Owens Valley Radio Observatory blazer monitoring program. We estimate the variability amplitudes using the intrinsic modulation index, and study the time-domain connection by cross-correlating the optical and radio light curves assuming power law power spectral density. Our sample objects are in general more variable in the optical than radio. We find correlated flares in about half of the objects, and correlated long-term trends in more than 40% of the objects. In these objects we estimate that at least 10%-50% of the optical emiss...

  2. The Megaparsec-scale X-ray Jet of The BL Lac Object OJ287

    Science.gov (United States)

    Marscher, Alan P.; Jorstad, Svetlana G.

    2011-03-01

    We present an X-ray image of the BL Lacertae (BL Lac) object OJ287 revealing a long jet, curved by 55° and extending 20'' or 90 kpc from the nucleus. This de-projects to >1 Mpc based on the viewing angle on parsec scales. Radio emission follows the general X-ray morphology but extends even farther from the nucleus. The upper limit to the isotropic radio luminosity, ~2 × 1024 W Hz-1, places the source in the Fanaroff-Riley 1 (FR 1) class, as expected for BL Lac objects. The spectral energy distribution indicates that the extended X-ray emission is from inverse Compton scattering of cosmic microwave background photons. In this case, the derived magnetic field is B ≈ 5 μG, the minimum electron energy is 7-40m e c 2, and the Doppler factor is δ ≈ 8 in a knot 8'' from the nucleus. The minimum total kinetic power of the jet is (1-2)×1045 erg s-1. Upstream of the bend, the width of the X-ray emission in the jet is about half the projected distance from the nucleus. This implies that the highly relativistic bulk motion is not limited to an extremely thin spine, as has been proposed previously for FR 1 sources. The bending of the jet, the deceleration of the flow from parsec to kiloparsec scales, and the knotty structure can all be caused by standing shocks inclined by ~7° to the jet axis. Moving shocks resulting from major changes in the flow properties can also reproduce the knotty structure, but such a model does not explain as many of the observational details.

  3. Multi-Color Microvariability in HBLs: 1ES 1959+650

    Science.gov (United States)

    Wills, W. L.; Carini, M. T.

    2003-12-01

    BL Lac objects are the most extreme members of the class of objects known as AGN. The defining characteristics of BL Lac objects are large amplitude continuum variations at all wavelengths, a featureless optical spectrum, and large amplitude, highly variable polarization. BL Lacs can be divided into subclasses, based on the peak of the synchrotron portion of their SED. In the HBL sub class, this peak occurs in the UV/X-ray wavelength range. We present the results of a study of the color dependency of microvariability(variations on timescales of minutes to hours) for the HBL 1ES 1959+650, using the Bell Observatory 0.6m telescope and the 1.3m Robotically Controlled Telescope. This research was funded via the Kentucky Space Grant Consortium, the Kentucky NSF EPSCoR program, the Kentucky NASA/EPSCoR program and the Applied Research and Technology Program at Western Kentucky University.

  4. The physical properties of Fermi TeV BL Lac objects' jets

    Science.gov (United States)

    Ding, N.; Zhang, X.; Xiong, D. R.; Zhang, H. J.

    2017-01-01

    We investigate the physical properties of Fermi TeV BL Lac objects' jets by modelling the quasi-simultaneous spectral energy distribution of 29 Fermi TeV BL Lacs in the frame of a one-zone leptonic synchrotron self-Compton model. Our main results are the following. (i) There is a negative correlation between B and δ in our sample, which suggests that B and δ are dependent on each other mainly in the Thomson regime. (ii) There are negative correlations between νsy and r, the νIC and r, which is a signature of the energy-dependent statistical acceleration or the stochastic acceleration. There is a significant correlation between r and s, which suggests that the curvature of the electron energy distribution is attributed to the energy-dependent statistical acceleration mechanism. (iii) By assuming one proton per relativistic electron, we estimate the jet power and radiative power. A size relation Pe ˜ Pp > Pr ≳ PB is found in our sample. The Pe > PB suggests that the jets are particle dominated, and the Pe ˜ Pp means that the mean energy of relativistic electrons approaches mp/me. There are not significant correlations between Pjet and black hole mass in high or low state with a subsample of 18 sources, which suggests that the jet power weakly depends on the black hole mass. (iv) There is a correlation between the changes in the flux density at 1 TeV and the changes in the γpeak, which suggests that the change/evolution of electron energy distribution may be mainly responsible for the flux variation.

  5. HESS J1943+213: a non-classical high-frequency-peaked BL Lac object

    CERN Document Server

    Straal, Samayra M; van Leeuwen, Joeri; Clarke, Tracy E; Dubner, Gloria; Frey, Sandor; Giacani, Elsa; Paragi, Zsolt

    2016-01-01

    HESS J1943+213 is an unidentified TeV source that is likely a high-frequency-peaked BL Lac (HBL) object but also compatible with a pulsar wind nebula (PWN) nature. Each of these enormously different astronomical interpretations is supported by some of the observed unusual characteristics. In order to finally classify and understand this object we took a three-pronged approach, through time-domain, high angular resolution, and multi-frequency radio studies. First, our deep time-domain observations with the Arecibo telescope failed to uncover the putative pulsar powering the proposed PWN. We conclude with ~70% certainty that HESS J1943+213 does not host a pulsar. Second, long-baseline interferometry of the source with e-MERLIN at 1.5- and 5- GHz, shows only a core, a point source at ~ 1 - 100 milli-arcsecond resolution. Its 2013 flux density is about one-third lower than detected in 2011 observations with similar resolution. This radio variability of the core strengthens the HBL object hypothesis. More evidence...

  6. The Megaparsec-Scale X-ray Jet of the BL Lac Object OJ287

    CERN Document Server

    Marscher, Alan P

    2010-01-01

    We present an X-ray image of the BL Lacertae object OJ287 revealing a long jet, curved by 55 degrees and extending 20 arcsec from the nucleus. This corresponds to a projected separation from the nucleus of 90 kpc, which de-projects to > 1 Mpc based on the viewing angle on parsec scales. Radio emission follows the general X-ray morphology but extends even farther from the nucleus. The upper limit to the isotropic radio luminosity, ~ 2E24 W/Hz, places the source in the Fanaroff-Riley 1 (FR 1) class, as expected for BL Lac objects. If the X-ray emission is from inverse Compton scattering of cosmic microwave background photons, as indicated by the spectral energy distribution, we derive a magnetic field B ~ 5 microgauss, minimum electron energy of 7-40mc^2, and Doppler factor of about 8 in a knot about 8 arcsec from the nucleus. The minimum total kinetic power of the jet is 1-2E45 erg/s, similar to the FR 1 radio galaxy 3C 120. The Doppler factor on parsec scales is about 2.5 times the value derived for the exten...

  7. Is Low-Frequency-Peaked BL Lac Object OJ 287 a TeV Emitter?

    Institute of Scientific and Technical Information of China (English)

    CHEN Liang; BAI Jin-Ming

    2010-01-01

    @@ It is well known that there are only two low-frequency-peaked BL Lac objects(LBLs:BL Lacertae and S5 0716+714)and one flat spectrum radio quasar(FSRQ:3C 279)among more than 30 active galactic nuclei (AGNs)with detected TeV emissions.We study the spectral energy distribution(SED)of a famous LBL OJ 287,whose light curve has a 12-y period.Using a homogeneous one-zone synchrotron + synchrotron-self Compton model,we model the quasi-simultaneous broad-band SED of OJ 287.With some reasonable assumptions,we extrapolate the model to the high state of OJ 287 and predict its γ-ray emissions.Taking into account the absorption of γ-ray by the extragalactic background light(EBL),we find that the TeV emission of OJ 287 in high state is slightly higher than the sensitivity of H.E.S.S.The study on SEDs of OJ 287 has implications to unveil the origin of jet activity during its 12-y period and the properties of EBL.

  8. Contemporaneous broadband observations of three high-redshift BL Lac Objects

    CERN Document Server

    ,

    2016-01-01

    We have collected broadband spectral energy distributions (SEDs) of three BL Lac objects, 3FGL J0022.1$-$1855 (z=0.689), 3FGL J0630.9$-$2406 (z >~ 1.239), and 3FGL J0811.2$-$7529 (z=0.774), detected by Fermi with relatively flat GeV spectra. By observing simultaneously in the near-IR to hard X-ray band, we can well characterize the high end of the synchrotron component of the SED. Thus, fitting the SEDs to synchro-Compton models of the dominant emission from the relativistic jet, we can constrain the underlying particle properties and predict the shape of the GeV Compton component. Standard extragalactic background light (EBL) models explain the high-energy absorption well, with poorer fits for high UV models. The fits show clear evidence for EBL absorption in the Fermi spectrum of our highest redshift source 3FGL J0630.9$-$2406. While synchrotron self-Compton models adequately describe the SEDs, the situation may be complicated by possible external Compton components. For 3FGL J0811.2$-$7529, we also discove...

  9. BL LAC OBJECT PKS B1144-379: AN EXTREME SCINTILLATOR

    Energy Technology Data Exchange (ETDEWEB)

    Turner, R. J.; Ellingsen, S. P.; Shabala, S. S.; Blanchard, J.; Lovell, J. E. J.; McCallum, J. N. [School of Mathematics and Physics, Private Bag 37, University of Tasmania, Hobart, TAS 7001 (Australia); Cimo, G. [Joint Institute for VLBI in Europe, Postbus 2, 7990 AA Dwingeloo (Netherlands)

    2012-08-01

    Rapid variability in the radio flux density of the BL Lac object PKS B1144-379 has been observed at four frequencies, ranging from 1.5 to 15 GHz, with the Very Large Array and the University of Tasmania's Ceduna antenna. Intrinsic and line-of-sight effects were examined as possible causes of this variability, with interstellar scintillation best explaining the frequency dependence of the variability timescales and modulation indices. This scintillation is consistent with a compact source 20-40 {mu}as or 0.15-0.3 pc in size. The inferred brightness temperature for PKS B1144-379 (assuming that the observed variations are due to scintillation) is 6.2 Multiplication-Sign 10{sup 12} K at 4.9 GHz, with approximately 10% of the total flux in the scintillating component. We show that scintillation surveys aimed at identifying variability timescales of days to weeks are an effective way to identify the active galactic nuclei with the highest brightness temperatures.

  10. Discovery of VHE gamma-rays from the BL Lac object PKS 0548-322

    CERN Document Server

    Akhperjanian, A G; de Almeida, U Barres; Bazer-Bachi, A R; Becherini, Y; Behera, B; Benbow, W; Bernlöhr, K; Bochow, A; Boisson, C; Bolmont, J; Borrel, V; Brucker, J; Brun, F; Brun, P; Bühler, R; Bulik, T; Büsching, I; Boutelier, T; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Chounet, L -M; Clapson, A C; Coignet, G; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubois, F; Dubus, G; Dyks, J; Dyrda, M; Egberts, K; Emmanoulopoulos, D; Espigat, P; Farnier, C; Feinstein, F; Fiasson, A; Förster, A; Fontaine, G; Füssling, M; Gabici, S; Gallant, Y A; Gérard, L; Gerbig, D; Giebels, B; Glicenstein, J F; Glück, B; Goret, P; Göring, D; Hauser, D; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hoffmann, A; Hofmann, W; Holleran, M; Hoppe, S; Horns, D; Jacholkowska, A; deJager, O C; Jahn, C; Jung, I; Katarzyński, K; Katz, U; Kaufmann, S; Kendziorra, E; Kerschhagg, M; Khangulyan, D; Khélifi, B; Keogh, D; Kluźniak, W; Kneiske, T; Komin, Nu; Kosack, K; Lamanna, G; Lenain, J -P; Lohse, T; Marandon, V; Martin, J M; Martineau-Huynh, O; Marcowith, A; Masbou, J; Maurin, D; McComb, T J L; Medina, M C; Moderski, R; Moulin, E; Naumann-Godo, M; deNaurois, M; Nedbal, D; Nekrassov, D; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Olive, J-F; Wilhelm, E de Oña; Orford, K J; Ostrowski, M; Panter, M; Arribas, M Paz; Pedaletti, G; Pelletier, G; Petrucci, P -O; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raubenheimer, B C; Raue, M; Rayner, S M; Renaud, M; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Ruppel, J; Sahakian, V; Santangelo, A; Schlickeiser, R; Schöck, F M; Schröder, R; Schwanke, U; Schwarzburg, S; Schwemmer, S; Shalchi, A; Sikora, M; Skilton, J L; Sol, H; Spangler, D; Stawarz, L; Steenkamp, R; Stegmann, C; Stinzing, F; Superina, G; Szostek, A; Tam, P H; Tavernet, J -P; Terrier, R; Tibolla, O; Tluczykont, M; vanEldik, C; Vasileiadis, G; Venter, C; Venter, L; Vialle, J P; Vincent, P; Vivier, M; Völk, H J; Volp, F; Wagner, S J; Ward, M; Zdziarski, A A; Zech, A

    2010-01-01

    PKS 0548-322 (z=0.069) is a ``high-frequency-peaked'' BL Lac object and a candidate very high energy (VHE, E>100 GeV) gamma-ray emitter, due to its high X-ray and radio flux. Observations at the VHE band provide insights into the origin of very energetic particles present in this source and the radiation processes at work. We report observations made between October 2004 and January 2008 with the H.E.S.S. array, a four imaging atmospheric-Cherenkov telescopes. Contemporaneous UV and X-ray observations with the Swift satellite in November 2006 are also reported. PKS 0548-322 is detected for the first time in the VHE band with H.E.S.S. We measure an excess of 216 gamma-rays corresponding to a significance of 5.6 standard deviations. The photon spectrum of the source is described by a power-law, with a photon index of Gamma=2.86 +/- 0.34 (stat) +/- 0.10 (sys). The integral flux above 200 GeV is 1.3 % of the flux of the Crab Nebula, and is consistent with being constant in time. Contemporaneous Swift/XRT observat...

  11. VERITAS Observations of the BL Lac Object PG 1553+113

    CERN Document Server

    Aliu, E; Aune, T; Barnacka, A; Behera, B; Beilicke, M; Benbow, W; Berger, K; Bird, R; Buckley, J H; Bugaev, V; Byrum, K; Cardenzana, J V; Cerruti, M; Chen, X; Ciupik, L; Connolly, M P; Cui, W; Dickinson, H J; Dumm, J; Eisch, J D; Errando, M; Falcone, A; Federici, S; Feng, Q; Finley, J P; Fortin, P; Fortson, L; Furniss, A; Galante, N; Gillanders, G H; Griffin, S; Griffiths, S T; Grube, J; Gyuk, G; Håkansson, N; Hanna, D; Holder, J; Hughes, G; Humensky, T B; Johnson, C A; Kaaret, P; Kertzman, P Kar M; Khassen, Y; Kieda, D; Krawczynski, H; Krennrich, F; Kumar, S; Lang, M J; Madhavan, A; McArthur, S; McCann, A; Meagher, K; Millis, J; Moriarty, P; Nieto, D; de Bhróithe, A O'Faoláin; Ong, R A; Orr, M; Otte, A N; Park, N; Perkins, J S; Pohl, M; Popkow, A; Prokoph, H; Pueschel, E; Quinn, J; Ragan, K; Rajotte, J; Reyes, L C; Reynolds, P T; Richards, G T; Roache, E; Sembroski, G H; Shahinyan, K; Staszak, D; Telezhinsky, I; Tucci, J V; Tyler, J; Varlotta, A; Vassiliev, V V; Wakely, S P; Weinstein, A; Welsing, R; Wilhelm, A; Williams, D A; Zitzer, B

    2014-01-01

    We present results from VERITAS observations of the BL Lac object PG 1553+113 spanning the years 2010, 2011, and 2012. The time-averaged spectrum, measured between 160 and 560\\,GeV, is well described by a power law with a spectral index of $4.33 \\pm 0.09$. The time-averaged integral flux above $200\\,$GeV measured for this period was $(1.69 \\pm 0.06) \\times 10^{-11} \\, \\mathrm{ph} \\, \\mathrm{cm}^{-2} \\, \\mathrm{s}^{-1}$, corresponding to 6.9\\% of the Crab Nebula flux. We also present the combined $\\gamma$-ray spectrum from the Fermi Large Area Telescope and VERITAS covering an energy range from 100~MeV to 560~GeV. The data are well fit by a power law with an exponential cutoff at $\\rm {101.9 \\pm 3.2 \\, \\mathrm{GeV}} $. The origin of the cutoff could be intrinsic to PG~1553+113 or be due to the $\\gamma$-ray opacity of our universe through pair production off the extragalactic background light (EBL). Given lower limits to the redshift of $\\rm z \

  12. Multiwavelength Observations of 6 BL Lac Objects in 2008-2012

    Directory of Open Access Journals (Sweden)

    Morozova D.A.

    2013-12-01

    Full Text Available We present results of 4 years of VLBA monitoring along with γ-ray and optical R-band photometric observations of 6 BL Lac objects (3C 66A, S5 0716+71, PKS 0735+17, S4 0954+68, W Com, and OT 081. We have analyzed total intensity images obtained with the VLBA at 43 GHz and investigated the kinematic evolution of the parsec scale jets of the sources. For all sources we compare flux variations in the VLBI core and bright superluminal knots with γ-ray and optical light curves. The majority of γ-ray flares have optical counterparts. 67% of the γ-ray events are coincident with the appearance of new superluminal knots and/or flares in the millimeter-wave core. These results support the conclusion that for many flares in blazars the region of the γ-ray and optical emission is located in the vicinity or downstream of the mm-wave VLBI core.

  13. Fermi LAT detection of a GeV gamma-ray flare from the BL Lac object AP Librae

    Science.gov (United States)

    Ciprini, Stefano

    2016-08-01

    The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux from a source positionally consistent with the BL Lac object AP Lib (also known as PKS 1514-24 and 3FGL J1517.6-2422), with radio counterpart position R.A.: 229.424221 deg, Dec.: -24.372076 deg, (J2000.0, Johnston et al. 1995, AJ, 110, 880).

  14. VERITAS OBSERVATIONS OF THE BL LAC OBJECT PG 1553+113

    Energy Technology Data Exchange (ETDEWEB)

    Aliu, E. [Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States); Archer, A.; Beilicke, M.; Buckley, J. H.; Bugaev, V. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Aune, T. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Barnacka, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Behera, B.; Chen, X. [DESY, Platanenallee 6, 15738 Zeuthen (Germany); Benbow, W.; Cerruti, M. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Berger, K. [Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware, Newark, DE 19716 (United States); Bird, R. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Byrum, K. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Cardenzana, J. V; Dickinson, H. J. [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Connolly, M. P. [School of Physics, National University of Ireland Galway, University Road, Galway (Ireland); Cui, W. [Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907 (United States); Dumm, J. [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); and others

    2015-01-20

    We present results from VERITAS observations of the BL Lac object PG 1553+113 spanning the years 2010, 2011, and 2012. The time-averaged spectrum, measured between 160 and 560 GeV, is well described by a power law with a spectral index of 4.33 ± 0.09. The time-averaged integral flux above 200 GeV measured for this period was (1.69 ± 0.06) × 10{sup –11} photons cm{sup –2} s{sup –1}, corresponding to 6.9% of the Crab Nebula flux. We also present the combined γ-ray spectrum from the Fermi Large Area Telescope and VERITAS covering an energy range from 100 MeV to 560 GeV. The data are well fit by a power law with an exponential cutoff at 101.9 ± 3.2 GeV. The origin of the cutoff could be intrinsic to PG 1553+113 or be due to the γ-ray opacity of our universe through pair production off the extragalactic background light (EBL). Given lower limits to the redshift of z > 0.395 based on optical/UV observations of PG 1553+113, the cutoff would be dominated by EBL absorption. Conversely, the small statistical uncertainties of the VERITAS energy spectrum have allowed us to provide a robust upper limit on the redshift of PG 1553+113 of z ≤ 0.62. A strongly elevated mean flux of (2.50 ± 0.14) × 10{sup –11} photons cm{sup –2} s{sup –1} (10.3% of the Crab Nebula flux) was observed during 2012, with the daily flux reaching as high as (4.44±0.71)×10{sup −11} photons cm{sup −2} s{sup −1} (18.3% of the Crab Nebula flux) on MJD 56048. The light curve measured during the 2012 observing season is marginally inconsistent with a steady flux, giving a χ{sup 2} probability for a steady flux of 0.03%.

  15. The Luminosity Function of the Host Galaxies of QSOs and BL Lac Objects

    CERN Document Server

    Carangelo, N; Treves, A

    2001-01-01

    A clear insight of the galaxies hosting active galactic nuclei is of fundamental importance for understanding the processes of galaxies and nuclei formation and their cosmic evolution. A good characterization of the host galaxies properties requires images of excellent quality in order to disentangle the light of the galaxy from that of the bright nucleus. To this aim HST has provided a major improvement of data on QSOs (Disney et al. 1995; Bahcall et al. 1996, 1997; Boyce et al. 1998; McLure et al. 1999; Hamilton et al. 2000; Kukula et al. 2001) and BL Lacs (Scarpa et al. 2000, Urry et al. 2000). We present a comparative study of low redshift QSO and BL Lac host galaxy luminosity function (HGLF). To this aim we have considered samples of BL Lacs (Urry et al. 2000) and QSOs (Bahcall et al. 1997; Boyce et al. 1998; McLure et al. 1999) that have been well resolved by images obtained with WFPC2 on board of HST.

  16. Computing Optical Variable Periods of BL Lac Object S5 0716+714 with Period04 Analysis Method

    Indian Academy of Sciences (India)

    Junping Fu; Xiong Zhang; Dingrong Xiong

    2014-09-01

    From a large volume of literature, we have collected effective observation of BL Lac object S5 0716+714 in the optical band, and constructed its long-term light curve from 1994 to 2006 AD. The light curve shows that S5 0716+714 is very active and exhibits very complicated non-sinusoidal variations. We used Period04 to analyse the period of light curve variation. Our results show that for S5 0716+714, the long-term period of variation is 3.3 yr which is consistent with the result of Raiter et al. (2003).

  17. Connection between inner jet kinematics and broadband flux variability in the BL Lac object S5 0716+714

    CERN Document Server

    Rani, B; Marscher, A P; Hodgson, J A; Fuhrmann, L; Angelakis, E; Britzen, S; Zensus, J A

    2015-01-01

    We present a high-frequency very long baseline interferometry (VLBI) kinematical study of the BL Lac object S5 0716+714 over the time period of September 2008 to October 2010. The aim of the study is to investigate the relation of the jet kinematics to the observed broadband flux variability. We find significant non-radial motions in the jet outflow of the source. In the radial direction, the highest measured apparent speed is \\sim37 c, which is exceptionally high, especially for a BL Lac object. Patterns in the jet flow reveal a roughly stationary feature \\sim0.15 mas downstream of the core. The long-term fits to the component trajectories reveal acceleration in the sub-mas region of the jet. The measured brightness temperature, T_{B}, follows a continuous trend of decline with distance, T_B \\propto r_{jet}^{-(2.36\\pm0.41)}, which suggests a gradient in Doppler factor along the jet axis. Our analysis suggest that a moving disturbance (or a shock wave) from the base of the jet produces the high-energy (optica...

  18. Discovery of a variable broad absorption line in the BL Lac object PKS B0138-097

    Institute of Scientific and Technical Information of China (English)

    Shao-Hua Zhang; Hui-Yuan Wang; Hong-Yan Zhou; Ting-Gui Wang; Peng Jiang

    2011-01-01

    We report the discovery of a broad absorption line (BAL) of ~104 km s-1in width in the previously known BL Lac object PKS 0138-097,which we tentatively identified as an Mg Ⅱ BAL.This is the first detection of a BAL,which is sometimes seen in powerful quasars with high accretion rates,in a BL Lac object.The BAL was clearly detected in its spectra spanning two epochs at a high luminosity state taken in the Sloan Digital Sky Survey (SDSS),while it disappeared in three SDSS spectra taken at a low luminosity state.The BAL and its variability pattern were also found in its historical multi-epoch spectra in the literature,but have been overlooked previously.In its high resolution radio maps,PKS 0138-097 shows a core plus a onesided parsec-scale jet.The BAL variability can be interpreted as follows:The optical emission is dominated by the core in a high state and by the jet in a low state and the BAL material is located between the core and jet so that the BAL appears only when the core is shining.Our discovery suggests that outflows may also be produced in active galactic nuclei at a low accreting state.

  19. An Analysis of Light Periods of BL Lac Object S5 0716+714 with the MUSIC Algorithm

    Science.gov (United States)

    Tang, Jie

    2012-07-01

    The multiple signal classification (MUSIC) algorithm is introduced to the estimation of light periods of BL Lac objects. The principle of the MUSIC algorithm is given, together with a testing on its spectral resolution by using a simulative signal. From a lot of literature, we have collected a large number of effective observational data of the BL Lac object S5 0716+714 in the three optical wavebands V, R, and I from 1994 to 2008. The light periods of S5 0716+714 are obtained by means of the MUSIC algorithm and average periodogram algorithm, respectively. It is found that there exist two major periodic components, one is the period of (3.33±0.08) yr, another is the period of (1.24±0.01) yr. The comparison of the performances of periodicity analysis of two algorithms indicates that the MUSIC algorithm has a smaller requirement on the sample length, as well as a good spectral resolution and anti-noise ability, to improve the accuracy of periodicity analysis in the case of short sample length.

  20. The Hybrid Nature of 0846+51W1: a BL Lac Object with a Narrow Line Seyfert 1 Nucleus

    Institute of Scientific and Technical Information of China (English)

    Hong-Yan Zhou; Ting-Gui Wang; Xiao-Bo Dong; Cheng Li; Xue-Guang Zhang

    2005-01-01

    We found a NLS1 nucleus in the extensively studied eruptive BL Lac object, 0846+51W1, out of a large sample of NLS1s compiled from the spectroscopic dataset of SDSS DR1. Its optical spectrum can be well decomposed into three components: a power law component from the relativistic jet, a stellar component from the host galaxy, and a component from a typical NLS1 nucleus. The emission line properties of 0846+51Wl, FWHM (Hβ)∽- 1710 km s-1 and [OⅢ]λ5007 /Hβ∽-0.32from its SDSS spectrum observed when it was in the faint state, fulfil the conventional definition of NLS1. Strong FelI emission is detected in the SDSS spectrum,which is also typical of NLS1s. We tried to estimate its central black hole mass using various techniques and found that 0846+51W1 is very likely emitting at a few × 10% of the Eddington luminosity. We speculate that Seyfert-like nuclei, including NLS1s, might be concealed in a significant fraction of BL Lacs but have remained largely unobserved because, often, their optical-UV continuum is overwhelmed by the synchrotron emission.

  1. AGILE confirmation of enhanced gamma-ray activity from the Blazar 1ES 1959+650

    Science.gov (United States)

    Lucarelli, F.; Pittori, C.; Verrecchia, F.; Bulgarelli, A.; Fioretti, V.; Zoli, A.; Piano, G.; Munar-Adrover, P.; Tavani, M.; Donnarumma, I.; Vercellone, S.; Striani, E.; Cardillo, M.; Gianotti, F.; Trifoglio, M.; Giuliani, A.; Mereghetti, S.; Caraveo, P.; Perotti, F.; Chen, A.; Argan, A.; Costa, E.; Del Monte, E.; Evangelista, Y.; Feroci, M.; Lazzarotto, F.; Lapshov, I.; Pacciani, L.; Soffitta, P.; Sabatini, S.; Vittorini, V.; Pucella, G.; Rapisarda, M.; Di Cocco, G.; Fuschino, F.; Galli, M.; Labanti, C.; Marisaldi, M.; Pellizzoni, A.; Pilia, M.; Trois, A.; Barbiellini, G.; Vallazza, E.; Longo, F.; Morselli, A.; Picozza, P.; Prest, M.; Lipari, P.; Zanello, D.; Cattaneo, P. W.; Rappoldi, A.; Colafrancesco, S.; Parmiggiani, N.; Ferrari, A.; Antonelli, A.; Giommi, P.; Salotti, L.; Valentini, G.; D'Amico, F.

    2016-06-01

    Following ATel #9148, reporting multi-wavelength activity from the BL Lac type blazar 1ES 1959+650, AGILE also detects increased gamma-ray emission above 100 MeV from a position compatible with this BL Lac source.

  2. Synchrotron and Compton Components and their Variability in BL Lac Objects

    CERN Document Server

    Giommi, P; Padovani, P; Tagliaferri, G

    2000-01-01

    BL Lacertae objects are extreme extragalactic sources characterized by theemission of strong and rapidly variable nonthermal radiation over the entireelectromagnetic spectrum. Synchrotron emission followed by inverse Comptonscattering in a relativistic beaming scenario is generally thought to be themechanism powering these objects. ...

  3. Multiwavelength observations of the blazar 1ES 1011+496 in Spring 2008

    Science.gov (United States)

    Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; Banerjee, B.; Bangale, P.; de Almeida, U. Barres; Barrio, J. A.; González, J. Becerra; Bednarek, W.; Bernardini, E.; Biasuzzi, B.; Biland, A.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carmona, E.; Carosi, A.; Chatterjee, A.; Clavero, R.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Lotto, B.; de Oña Wilhelmi, E.; Mendez, C. Delgado; Pierro, F. Di; Prester, D. Dominis; Dorner, D.; Doro, M.; Einecke, S.; Elsaesser, D.; Fernández-Barral, A.; Fidalgo, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; Galindo, D.; López, R. J. García; Garczarczyk, M.; Terrats, D. Garrido; Gaug, M.; Giammaria, P.; (Eisenacher), D. Glawion; Godinović, N.; Muñoz, A. González; Guberman, D.; Hanabata, Y.; Hayashida, M.; Herrera, J.; Hose, J.; Hrupec, D.; Hughes, G.; Idec, W.; Kodani, K.; Konno, Y.; Kubo, H.; Kushida, J.; Barbera, A. La; Lelas, D.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Coto, R.; López-Oramas, A.; Lorenz, E.; Majumdar, P.; Makariev, M.; Mallot, K.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Nakajima, D.; Neustroev, V.; Niedzwiecki, A.; Rosillo, M. Nievas; Nilsson, K.; Nishijima, K.; Noda, K.; Orito, R.; Overkemping, A.; Paiano, S.; Palacio, J.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Persic, M.; Poutanen, J.; Moroni, P. G. Prada; Prandini, E.; Puljak, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Garcia, J. Rodriguez; Rügamer, S.; Saito, T.; Satalecka, K.; Scapin, V.; Schultz, C.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Stamerra, A.; Steinbring, T.; Strzys, M.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Torres, D. F.; Toyama, T.; Treves, A.; Verguilov, V.; Vovk, I.; Ward, J. E.; Will, M.; Wu, M. H.; Zanin, R.; Lucarelli, F.; Pittori, C.; Vercellone, S.; Berdyugin, A.; Carini, M. T.; Lähteenmäki, A.; Pasanen, M.; Pease, A.; Sainio, J.; Tornikoski, M.; Walters, R.

    2016-07-01

    The BL Lac object 1ES 1011+496 was discovered at very high energy (VHE, E > 100GeV) γ-rays by Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) in Spring 2007. Before that the source was little studied in different wavelengths. Therefore, a multiwavelength (MWL) campaign was organized in Spring 2008. Along MAGIC, the MWL campaign included the Metsähovi Radio Observatory, Bell and Kungliga Vetenskapsakademien (KVA) optical telescopes and the Swift and AGILE satellites. MAGIC observations span from 2008 March to May for a total of 27.9 h, of which 19.4 h remained after quality cuts. The light curve showed no significant variability yielding an integral flux above 200 GeV of (1.3 ± 0.3) × 10-11 photons cm-2 s-1. The differential VHE spectrum could be described with a power-law function with a spectral index of 3.3 ± 0.4. Both results were similar to those obtained during the discovery. Swift X-ray Telescope observations revealed an X-ray flare, characterized by a harder-when-brighter trend, as is typical for high synchrotron peak BL Lac objects (HBL). Strong optical variability was found during the campaign, but no conclusion on the connection between the optical and VHE γ-ray bands could be drawn. The contemporaneous spectral energy distribution shows a synchrotron-dominated source, unlike concluded in previous work based on non-simultaneous data, and is well described by a standard one-zone synchrotron self-Compton model. We also performed a study on the source classification. While the optical and X-ray data taken during our campaign show typical characteristics of an HBL, we suggest, based on archival data, that 1ES 1011+496 is actually a borderline case between intermediate and high synchrotron peak frequency BL Lac objects.

  4. Fermi LAT detection of the first GeV gamma-ray flare from the BL Lac object S5 2007+77

    Science.gov (United States)

    Cutini, Sara

    2016-02-01

    The Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope, has observed for the first time on daily time-scales gamma-ray outburst activity from a source positionally consistent with the BL Lac object S5 2007+77.

  5. Chaotic Behaviour of Intra-Day Variability of BL Lac Object S5 0716+714

    Indian Academy of Sciences (India)

    Shuhong Li; Jianwen Ou; Zheng Liu

    2014-06-01

    An optical monitoring shows Blazar object S5 0716+714 has complex Intra-Day Variability (IDV) behaviour. In this paper, we introduce a method of non-linear time series analysis, and calculate the correlation dimension of the IDV light curves of S5 0716+714 over seven nights in the December of 2006. According to our calculations, the correlation dimension ≈ 1.993-5.178 for all of the observed data, it is implied that the IDV behaviour may be a chaotic system with some additional noise.

  6. Discovery of high and very high-energy emission from the BL Lac object SHBL J001355.9-185406

    CERN Document Server

    :,; Acero, F; Aharonian, F; Akhperjanian, A G; Angüner, E; Anton, G; Balenderan, S; Balzer, A; Barnacka, A; Becherini, Y; Tjus, J Becker; Bernlöhr, K; Birsin, E; Bissaldi, E; Biteau, J; Boisson, C; Bolmont, J; Bordas, P; Brucker, J; Brun, F; Brun, P; Bulik, T; Carrigan, S; Casanova, S; Cerruti, M; Chadwick, P M; Chalme-Calvet, R; Chaves, R C G; Cheesebrough, A; Chrétien, M; Colafrancesco, S; Cologna, G; Conrad, J; Couturier, C; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; deWilt, P; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Edwards, T; Egberts, K; Eger, P; Espigat, P; Farnier, C; Fegan, S; Feinstein, F; Fernandes, M V; Fernandez, D; Fiasson, A; Fontaine, G; Förster, A; Füßling, M; Gajdus, M; Gallant, Y A; Garrigoux, T; Gast, H; Giebels, B; Glicenstein, J F; Göring, D; Grondin, M -H; Grudzińska, M; Häffner, S; Hague, J D; Hahn, J; Harris, J; Heinzelmann, G; Henri, G; Hermann, G; Hervet, O; Hillert, A; Hinton, J A; Hofmann, W; Hofverberg, P; Holler, M; Horns, D; Jacholkowska, A; Jahn, C; Jamrozy, M; Janiak, M; Jankowsky, F; Jung, I; Kastendieck, M A; Katarzyński, K; Katz, U; Kaufmann, S; Khélifi, B; Kieffer, M; Klepser, S; Klochkov, D; Kluźniak, W; Kneiske, T; Kolitzus, D; Komin, Nu; Kosack, K; Krakau, S; Krayzel, F; Krüger, P P; Laffon, H; Lamanna, G; Lefaucheur, J; Lemoine-Goumard, M; Lenain, J -P; Lennarz, D; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Maurin, G; Maxted, N; Mayer, M; McComb, T J L; Medina, M C; Méhault, J; Menzler, U; Meyer, M; Moderski, R; Mohamed, M; Moulin, E; Murach, T; Naumann, C L; de Naurois, M; Nedbal, D; Niemiec, J; Nolan, S J; Oakes, L; Ohm, S; Wilhelmi, E de O\; Opitz, B; Ostrowski, M; Oya, I; Panter, M; Parsons, R D; Arribas, M Paz; Pekeur, N W; Pelletier, G; Perez, J; Petrucci, P -O; Peyaud, B; Pita, S; Poon, H; Pühlhofer, G; Punch, M; Quirrenbach, A; Raab, S; Raue, M; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Sahakian, V; Sanchez, D A; Santangelo, A; Schlickeiser, R; Schüssler, F; Schulz, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Sol, H; Spengler, G; Spieß, F; Stawarz, {Ł }; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Szostek, A; Tavernet, J -P; Terrier, R; Tluczykont, M; Trichard, C; Valerius, K; van Eldik, C; Vasileiadis, G; Venter, C; Viana, A; Vincent, P; Völk, H J; Volpe, F; Vorster, M; Wagner, S J; Wagner, P; Ward, M; Weidinger, M; White, R; Wierzcholska, A; Willmann, P; Wörnlein, A; Wouters, D; Zacharias, M; Zajczyk, A; Zdziarski, A A; Zech, A; Zechlin, H -S

    2013-01-01

    The detection of the high-frequency peaked BL Lac object (HBL) SHBL J001355.9-185406 ($z$=0.095) at high (HE; 100 MeV$100\\,{\\rm GeV}$) with the \\fer\\ Large Area Telescope (LAT) and the High Energy Stereoscopic System (H.E.S.S.) is reported. Dedicated observations have been performed with the H.E.S.S. telescopes, leading to a detection at the $5.5\\,\\sigma$ significance level. The measured flux above 310 GeV is $(8.3 \\pm 1.7_{\\rm{stat}}\\pm 1.7_{\\rm{sys}})\\times 10^{-13}$ photons \\cms\\ (about 0.6% of that of the Crab Nebula), and the power law spectrum has a photon index of \\indexHESS. Using 3.5 years of publicly available \\fla\\ data, a faint counterpart has been detected in the LAT data at the $5.5\\,\\sigma$ significance level, with an integrated flux above 300 MeV of $(9.3 \\pm 3.4_{\\rm stat} \\pm 0.8_{\\rm sys})\\times 10^{-10}$ photons \\cms\\ and a photon index of $\\Gamma = 1.96 \\pm 0.20_{\\rm stat} \\pm 0.08_{\\rm sys}$. X-ray observations with \\textit{Swift}-XRT allow the synchrotron peak energy in $\

  7. EVN Observations of HESS J1943+213: Evidence for an Extreme TeV BL Lac Object

    CERN Document Server

    Akiyama, Kazunori; Tanaka, Yasuyuki T; Nagai, Hiroshi; Giroletti, Marcello; Honma, Mareki

    2016-01-01

    We report on the 1.6 GHz (18 cm) VLBI observations of the unresolved, steady TeV source HESS J1943+213 located in the Galactic plane, performed with the European VLBI Network (EVN) in 2014. Our new observations with a nearly full EVN array provide the deepest image of HESS J1943+213 at the highest resolution ever achieved, enabling us to resolve the long-standing issues of the source identification. The milliarcsecond-scale structure of HESS J1943+213 has a clear asymmetric morphology, consisting of a compact core and a diffuse jet-like tail. This is broadly consistent with the previous e-EVN observations of the source performed in 2011, and re-analyzed in this work. The core component is characterized by the brightness temperature of $\\gtrsim1.8 \\times 10^9$ K, which is typical for low-luminosity blazars in general. Overall, radio properties of HESS J1943+213 are consistent with the source classification as an "extreme high-frequency-peaked BL Lac object". Remarkably, we note that since HESS J1943+213 does n...

  8. Quasi-simultaneous observations of BL Lac object Mrk 501 in X-ray, UV, visible, IR, and radio frequencies

    Science.gov (United States)

    Kondo, Y.; Worrall, D. M.; Oke, J. B.; Yee, H. K. C.; Neugebauer, G.; Matthews, K.; Feldman, P. A.; Mushotzky, R. F.; Hackney, R. L.; Hackney, K. R. H.

    1981-01-01

    Observations in the X-ray, UV, visible, IR and radio regions of the BL Lac object Mrk 501 made over the course of two months are reported. The measurements were made with the A2 experiment on HEAO 1 (X-ray), the SWP and LWR cameras on IUE (UV), the 5-m Hale telescope (visible), the 2.5-m telescope at Mount Wilson (IR), the NRAO 92-m radio telescope at Green Bank (4750 MHz) and the 46-m radio telescope at the Algonquin Observatory (10275 and 10650 MHz). The quasi-simultaneously observed spectral slope is found to be positive and continuous from the X-ray to the UV, but to gradually flatten and possibly turn down from the mid-UV to the visible; the optical-radio emission cannot be accounted for by a single power law. The total spectrum is shown to be compatible with a synchrotron self-Compton emission mechanism, while the spectrum from the visible to the X-ray is consistent with synchrotron radiation or inverse-Compton scattering by a hot thermal electron cloud. The continuity of the spectrum from the UV to the X-ray is noted to imply a total luminosity greater than previous estimates by a factor of 3-4.

  9. Quasi-simultaneous observations of BL Lac object Mrk 501 in X-ray, UV, visible, IR, and radio frequencies

    Science.gov (United States)

    Kondo, Y.; Worrall, D. M.; Oke, J. B.; Yee, H. K. C.; Neugebauer, G.; Matthews, K.; Feldman, P. A.; Mushotzky, R. F.; Hackney, R. L.; Hackney, K. R. H.

    1981-01-01

    Observations in the X-ray, UV, visible, IR and radio regions of the BL Lac object Mrk 501 made over the course of two months are reported. The measurements were made with the A2 experiment on HEAO 1 (X-ray), the SWP and LWR cameras on IUE (UV), the 5-m Hale telescope (visible), the 2.5-m telescope at Mount Wilson (IR), the NRAO 92-m radio telescope at Green Bank (4750 MHz) and the 46-m radio telescope at the Algonquin Observatory (10275 and 10650 MHz). The quasi-simultaneously observed spectral slope is found to be positive and continuous from the X-ray to the UV, but to gradually flatten and possibly turn down from the mid-UV to the visible; the optical-radio emission cannot be accounted for by a single power law. The total spectrum is shown to be compatible with a synchrotron self-Compton emission mechanism, while the spectrum from the visible to the X-ray is consistent with synchrotron radiation or inverse-Compton scattering by a hot thermal electron cloud. The continuity of the spectrum from the UV to the X-ray is noted to imply a total luminosity greater than previous estimates by a factor of 3-4.

  10. Multi-wavelength study of flaring activity in BL Lac object S5 0716+714 during 2015 outburst

    CERN Document Server

    Chandra, Sunil; Kushwaha, Pankaj; Singh, K P; Bottcher, M; Kaur, Navpreet; Baliyan, K S

    2015-01-01

    We present a detailed investigation of the flaring activity observed from a BL Lac object, S5 0716+714 , during its brightest ever optical state in the second half of January 2015. Observed almost simultaneously in the optical, X-rays and {\\gamma}-rays, a significant change in the degree of optical polarization (PD) and a swing in the position angle (PA) of polarization were recorded. A detection in the TeV (VHE) was also reported by the MAGIC consortium during this flaring episode. Two prominent sub-flares, peaking about 5-days apart, were seen in almost all the energy bands. The multi-wavelength light-curves, spectral energy distribution (SED) and polarization are modeled using the time-dependent code developed by Zhang et al. (2014). This model assumes a straight jet threaded by large scale helical magnetic fields taking into account the light travel time effects, incorporating synchrotron flux and polarization in 3D geometry. The rapid variation in PD and rotation in PA are most likely due to re-connectio...

  11. Correlation between the TeV and X-ray emission in high--energy peaked BL Lac objects

    CERN Document Server

    Katarzynski, K; Tavecchio, F; Maraschi, L; Fossati, G; Mastichiadis, A

    2004-01-01

    We discuss the correlation between the evolution of the TeV emission and X-ray radiation observed in high-energy peaked BL Lac objects. We describe such a correlation by a simple power law. In the first part of this work we present correlations obtained for the activity of Mrk~501 observed in 1997 April and for the activity of Mrk~421 observed in 2000 February. We also discuss results of similar correlation obtained for this source by other authors. They report an almost quadratic correlations observed between the evolution of the TeV and X-ray emission. In the second part of this paper we present a phenomenological model which describes the evolution of the synchrotron and inverse Compton emission of a simple spherical homogeneous source. Neglecting the radiative cooling of the particles we derive analytical expressions that describe the evolution. Then we use a numerical code to investigate the impact of radiative cooling on the evolution. The quadratic correlation observed during the decay phase of the fla...

  12. Multiwavelength Variability Study of the Classical BL Lac Object PKS 0735+178 on Timescales Ranging from Decades to Minutes

    Science.gov (United States)

    Goyal, Arti; Stawarz, Łukasz; Ostrowski, Michał; Larionov, Valeri; Gopal-Krishna; Wiita, Paul J.; Joshi, Santosh; Soida, Marian; Agudo, Iván

    2017-03-01

    We present the results of our power spectral analysis for the BL Lac object PKS 0735+178, utilizing the Fermi-LAT survey at high-energy γ-rays, several ground-based optical telescopes, and single-dish radio telescopes operating at GHz frequencies. The novelty of our approach is that, by combining long-term and densely sampled intra-night light curves in the optical regime, we were able to construct for the first time the optical power spectrum of the blazar for a time domain extending from 23 years down to minutes. Our analysis reveals that: (1) the optical variability is consistent with a pure red noise, for which the power spectral density can be well approximated by a single power law throughout the entire time domain probed; (2) the slope of power spectral density at high-energy γ-rays (∼1) is significantly flatter than that found at radio and optical frequencies (∼2) within the corresponding time variability range; (3) for the derived power spectra, we did not detect any low-frequency flattening, nor do we see any evidence for cutoffs at the highest frequencies down to the noise floor levels due to measurement uncertainties. We interpret our findings in terms of a model where the blazar variability is generated by the underlying single stochastic process (at radio and optical frequencies), or a linear superposition of such processes (in the γ-ray regime). Along with the detailed PSD analysis, we also present the results of our extended (1998–2015) intra-night optical monitoring program and newly acquired optical photo-polarimetric data for the source.

  13. X-ray and TeV Gamma-Ray Emission from Parallel Electron-Positron or Electron-Proton Beams in BL Lac Objects

    Science.gov (United States)

    Krawczynski, Henric

    2007-04-01

    In this contribution we discuss models of the X-rays and TeV gamma-ray emission from BL Lac objects based on parallel electron-positron or electron-proton beams that form close to the central black hole owing to the strong electric fields generated by the accretion disk and possibly also by the black hole itself. Fitting the energy spectrum of the BL Lac object Mrk 501, we obtain tight constrains on the beam properties. Launching a sufficiently energetic beam requires rather strong magnetic fields close to the black hole 100-1000 G. However, the model fits imply that the magnetic field in the emission region is only 0.02 G. Thus, the particles are accelerated close to the black hole and propagate a considerable distance before instabilities trigger the dissipation of energy through synchrotron and self-Compton emission. We discuss various approaches to generate enough power to drive the jet and, at the same time, to accelerate particles to 20 TeV energies. Although the parallel beam model has its own problems, it explains some of the long-standing problems that plague models based on Fermi type particle acceleration, like the presence of a very high minimum Lorentz factor of accelerated particles. We conclude with a brief discussion of the implications of the model for the difference between the processes of jet formation in BL Lac type objects and in quasars.

  14. Optical monitoring of BL Lac object S5 0716+714 and FSRQ 3C 273 from 2000 to 2014

    Science.gov (United States)

    Yuan, Yu-Hai; Fan, Jun-hui; Tao, Jun; Qian, Bo-Chen; Costantin, Denise; Xiao, Hu-Bing; Pei, Zhi-Yuan; Lin, Chao

    2017-09-01

    Context. Using the 1.56 m telescope at the Shanghai Observatory (ShAO), China, we monitored two sources, BL Lac object S5 0716+714 and flat spectrum radio quasar (FSRQ) 3C 273. For S5 0716+714, we report 4969 sets of CCD (Charge-coupled Device) photometrical optical observations (1369 for V band, 1861 for R band and 1739 for I band) in the monitoring time from Dec. 4, 2000 to Apr. 5, 2014. For 3C 273, we report 460 observations (138 for V band, 146 for R band and 176 for I band) in the monitoring time from Mar. 28, 2006 to Apr. 9, 2014. Aims: The observations provide us with a large amount of data to analyze the short-term and long-term optical variabilities. Based on the variable timescales, we can estimate the central black hole mass and the Doppler factor. An abundance of multi-band observations can help us to analyze the relations between the brightness and spectrum. Methods: We use Gaussian fitting to analyze the intra-day light curves and obtain the intra-day variability (IDV) timescales. We use the discrete correlation function (DCF) method and Jurkevich method to analyze the quasi-periodic variability. Based on the VRI observations, we use the linear fitting to analyze the relations between brightness and spectrum. Results: The two sources both show IDV properties for S5 0716+714. The timescales are in the range from 17.3 min to 4.82 h; for 3C 273, the timescale is ΔT = 35.6 min. Based on the periodic analysis methods, we find the periods PV = 24.24 ± 1.09 days, PR = 24.12 ± 0.76 days, PI = 24.82 ± 0.73 days for S5 0716+714, and P = 12.99 ± 0.72, 21.76 ± 1.45 yr for 3C 273. The two sources displayed the "bluer-when-brighter" spectral evolution properties. Conclusions: S5 0716+714 and 3C 273 are frequently studied objects. The violent optical variability and IDV may come from the jet. Gaussian fitting can be used to analyze IDVs. The relations between brightness (flux density) and spectrum are strongly influenced by the frequency. A table of the

  15. Jet/accretion and Unification for FSRQs/FRII and BL Lac objects/FRI radio galaxies

    CERN Document Server

    Chen, Yongyun; Zhang, Haojing; Xiong, Dingrong; Yu, Xiaoling; Cha, Yongjuan; Li, Bijun; Huang, Xia

    2015-01-01

    We compiled a sample of 24 flat-spectrum radio quasars (FSRQs), 21 BL Lacs, 13 FRI and 12 FRII radio galaxies to study the jet power and broad-line luminosity relation, and the jet power and black hole mass relation. Furthermore, we obtain the histograms of key parameters. Our main results are as the follows:(i) We found that the FSRQs are roughly separated from BL Lacs by the Ledlow-Owen FRI/FRII dividing line in the $\\rm{\\log{P_{jet}}-\\log{M}}$ plane. This result supports the unification model that BL Lacs unify with FRI radio galaxies and FSRQs unify with FRII radio galaxies.(ii)We found that the coefficient of the best-fit linear regression equation of $\\rm{\\log{L_{BLR}}-\\log{P_{jet}}}$ relation is very close to 1 for our sample. The correlation between broad line luminosity and jet power is significant which supports that jet power has a close link with accretion.

  16. Multi-Wavelength Observations of the Blazar 1ES 1011+496 in Spring 2008

    CERN Document Server

    Ahnen, M L; Antonelli, L A; Antoranz, P; Babic, A; Banerjee, B; Bangale, P; de Almeida, U Barres; Barrio, J A; Gonzalez, J Becerra; Bednarek, W; Bernardini, E; Biasuzzi, B; Biland, A; Blanch, O; Bonnefoy, S; Bonnoli, G; Borracci, F; Bretz, T; Carmona, E; Carosi, A; Chatterjee, A; Clavero, R; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Caneva, G; De Lotto, B; Wilhelmi, E de Ona; Mendez, C Delgado; Di Pierro, F; Prester, D Dominis; Dorner, D; Doro, M; Einecke, S; Elsaesser, D; Fernandez-Barral, A; Fidalgo, D; Fonseca, M V; Font, L; Frantzen, K; Fruck, C; Galindo, D; Lopez, R J Garcia; Garczarczyk, M; Terrats, D Garrido; Gaug, M; Giammaria, P; Glawion, D; Godinovic, N; Munoz, A Gonzalez; Guberman, D; Hanabata, Y; Hayashida, M; Herrera, J; Hose, J; Hrupec, D; Hughes, G; Idec, W; Kodani, K; Konno, Y; Kubo, H; Kushida, J; La Barbera, A; Lelas, D; Lindfors, E; Lombardi, S; Longo, F; Lopez, M; Lopez-Coto, R; Lopez-Oramas, A; Lorenz, E; Majumdar, P; Makariev, M; Mallot, K; Maneva, G; Manganaro, M; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martinez, M; Mazin, D; Menzel, U; Miranda, J M; Mirzoyan, R; Moralejo, A; Nakajima, D; Neustroev, V; Niedzwiecki, A; Rosillo, M Nievas; Nilsson, K; Nishijima, K; Noda, K; Orito, R; Overkemping, A; Paiano, S; Palacio, J; Palatiello, M; Paneque, D; Paoletti, R; Paredes, J M; Paredes-Fortuny, X; Persic, M; Poutanen, J; Moroni, P G Prada; Prandini, E; Puljak, I; Reinthal, R; Rhode, W; Ribo, M; Rico, J; Garcia, J Rodriguez; Rugamer, S; Saito, T; Satalecka, K; Scapin, V; Schultz, C; Schweizer, T; Shore, S N; Sillanpaa, A; Sitarek, J; Snidaric, I; Sobczynska, D; Stamerra, A; Steinbring, T; Strzys, M; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzic, T; Tescaro, D; Teshima, M; Thaele, J; Torres, D F; Toyama, T; Treves, A; Verguilov, V; Vovk, I; Ward, J E; Will, M; Wu, M H; Zanin, R; Lucarelli, F; Pittori, C; Berdyugin, A; Carini, M T; Lahteenmaki, A; Pasanen, M; Pease, A; Sainio, J; Tornikoski, M; Walters, R

    2016-01-01

    The BL Lac object 1ES 1011+496 was discovered at Very High Energy gamma-rays by MAGIC in spring 2007. Before that the source was little studied in different wavelengths. Therefore a multi-wavelength (MWL) campaign was organized in spring 2008. Along MAGIC, the MWL campaign included the Metsahovi radio observatory, Bell and KVA optical telescopes and the Swift and AGILE satellites. MAGIC observations span from March to May, 2008 for a total of 27.9 hours, of which 19.4 hours remained after quality cuts. The light curve showed no significant variability. The differential VHE spectrum could be described with a power-law function. Both results were similar to those obtained during the discovery. Swift XRT observations revealed an X-ray flare, characterized by a harder when brighter trend, as is typical for high synchrotron peak BL Lac objects (HBL). Strong optical variability was found during the campaign, but no conclusion on the connection between the optical and VHE gamma-ray bands could be drawn. The contempo...

  17. Discovery of Variability in the Very High Energy Gamma-Ray Emission of 1ES 1218+304 with VERITAS

    CERN Document Server

    Acciari, V A; Beilicke, M; Benbow, W; Boltuch, D; Böttcher, M; Bradbury, S M; Bugaev, V; Byrum, K; Cesarini, A; Ciupik, L; Cogan, P; Cui, W; Dickherber, R; Duke, C; Falcone, A; Finley, J P; Finnegan, G; Fortson, L; Furniss, A; Galante, N; Gall, D; Gibbs, K; Guenette, R; Gillanders, G H; Godambe, S; Grube, J; Hanna, D; Hui, C M; Humensky, T B; Imran, A; Kaaret, P; Karlsson, N; Kertzman, M; Kieda, D; Krawczynski, H; Krennrich, F; Lang, M J; LeBohec, S; Maier, G; McArthur, S; McCann, A; Moriarty, P; Nagai, T; Ong, R A; Otte, A N; Pandel, D; Perkins, J S; Pichel, A; Pohl, M; Quinn, J; Ragan, K; Reyes, L C; Reynolds, P T; Roache, E; Rose, H J; Schroedter, M; Sembroski, G H; Smith, A W; Steele, D; Swordy, S P; Theiling, M; Thibadeau, S; Vassiliev, V V; Vincent, S; Wakely, S P; Weekes, T C; Weinstein, A; Weisgarber, T; Williams, D A; 10.1088/2041-8205/709/2/L163

    2010-01-01

    We present results from an intensive VERITAS monitoring campaign of the high-frequency peaked BL Lac object 1ES 1218+304 in 2008/2009. Although 1ES 1218+304 was detected previously by MAGIC and VERITAS at a persistent level of ~6% of the Crab Nebula flux, the new VERITAS data reveal a prominent flare reaching ~20% of the Crab. While very high energy (VHE) flares are quite common in many nearby blazars, the case of 1ES 1218+304 (redshift z = 0.182) is particularly interesting since it belongs to a group of blazars that exhibit unusually hard VHE spectra considering their redshifts. When correcting the measured spectra for absorption by the extragalactic background light, 1ES 1218+304 and a number of other blazars are found to have differential photon indices less than 1.5. The difficulty in modeling these hard spectral energy distributions in blazar jets has led to a range of theoretical gamma-ray emission scenarios, one of which is strongly constrained by these new VERITAS observations. We consider the implic...

  18. MAGIC detection of very high energy γ-ray emission from the low-luminosity blazar 1ES 1741+196

    Science.gov (United States)

    Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Arcaro, C.; Babic, A.; Banerjee, B.; Bangale, P.; Barres de Almeida, U.; Barrio, J. A.; Bednarek, W.; Bernardini, E.; Berti, A.; Biasuzzi, B.; Biland, A.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Buson, S.; Carosi, A.; Chatterjee, A.; Clavero, R.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; de Oña Wilhelmi, E.; Di Pierro, F.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher Glawion, D.; Elsaesser, D.; Engelkemeier, M.; Fallah Ramazani, V.; Fernández-Barral, A.; Fidalgo, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Giammaria, P.; Godinović, N.; Gora, D.; Guberman, D.; Hadasch, D.; Hahn, A.; Hayashida, M.; Herrera, J.; Hose, J.; Hrupec, D.; Hughes, G.; Idec, W.; Kodani, K.; Konno, Y.; Kubo, H.; Kushida, J.; La Barbera, A.; Lelas, D.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Coto, R.; Majumdar, P.; Makariev, M.; Mallot, K.; Maneva, G.; Manganaro, M.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Moretti, E.; Nakajima, D.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nilsson, K.; Nishijima, K.; Noda, K.; Nogués, L.; Paiano, S.; Palacio, J.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Pedaletti, G.; Peresano, M.; Perri, L.; Persic, M.; Poutanen, J.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Garcia, J. R.; Reichardt, I.; Rhode, W.; Ribó, M.; Rico, J.; Saito, T.; Satalecka, K.; Schroeder, S.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Stamerra, A.; Strzys, M.; Surić, T.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Torres, D. F.; Toyama, T.; Treves, A.; Vanzo, G.; Verguilov, V.; Vovk, I.; Ward, J. E.; Will, M.; Wu, M. H.; Zanin, R.; Becerra González, J.; Rani, B.; Krauss, F.; Perri, M.; Verrecchia, F.; Reinthal, R.

    2017-06-01

    We present the first detection of the nearby (z = 0.084) low-luminosity BL Lac object 1ES 1741+196 in the very high energy (E > 100 GeV) band. This object lies in a triplet of interacting galaxies. Early predictions had suggested 1ES 1741+196 to be, along with several other high-frequency BL Lac sources, within the reach of MAGIC detectability. Its detection by MAGIC, later confirmed by VERITAS, helps to expand the small population of known TeV BL Lacs. The source was observed with the MAGIC telescopes between 2010 April and 2011 May, collecting 46 h of good quality data. These observations led to the detection of the source at 6.0 σ confidence level, with a steady flux F(>100 GeV) = (6.4 ± 1.7stat ± 2.6syst) × 10-12 ph cm-2s-1 and a differential spectral photon index Γ = 2.4 ± 0.2stat ± 0.2syst in the range of ˜80 GeV-3 TeV. To study the broad-band spectral energy distribution (SED) simultaneous with MAGIC observations, we use KVA, Swift/UVOT and XRT and Fermi/LAT data. One-zone synchrotron-self-Compton (SSC) modelling of the SED of 1ES 1741+196 suggests values for the SSC parameters that are quite common among known TeV BL Lacs except for a relatively low Doppler factor and slope of electron energy distribution. A thermal feature seen in the SED is well matched by a giant elliptical's template. This appears to be the signature of thermal emission from the host galaxy, which is clearly resolved in optical observations.

  19. Photographic photometry of compact extragalactic objects. VI. [BL Lac OJ 287, B2 1101+38, IZw 1727+50, IZw 0051+12, 3C 351, 3C 120

    Energy Technology Data Exchange (ETDEWEB)

    Hagen-Thorn, V.A.; Perevozchikova, A.I.; Skulova, N.M.; Ershtadt, S.G.; Yakovleya, V.A.

    1978-01-01

    The results of photographic photometry in B band of 7 compact extragalactic objects for 1975 are given. The light curves of BL Lac (1968-1975) and OJ 287 (1971-1975) are investigated for periodicity. It is found that the light curves of both objects seem to have components with amplitudes of 0.5 m and periods of 178 days for BL Lac and 184 days for OJ 287. 11 figures, 1 table.

  20. Fermi-LAT detection of hard spectrum and enhanced gamma-ray emission from the BL Lac object PKS 1717+177

    Science.gov (United States)

    Ciprini, Stefano

    2015-12-01

    The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has observed a gamma-ray flare from a source positionally consistent with the BL Lac object PKS 1717+177 (also known as S3 1717+17, OT 129, and 3FGL J1719.2+1744, Acero et al. 2015, ApJS, 218, 23), with radio coordinates (J2000.0), R.A.: 259.804368 deg, Dec.: 17.751788 deg (Johnston et al. 1995, AJ, 110, 880).

  1. Fermi LAT detection of the first GeV gamma-ray flare from the BL Lac object TXS 2241+406

    Science.gov (United States)

    Buson, Sara

    2015-02-01

    The Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope, has observed for the first time on daily timescales gamma-ray outburst activity from a source positionally consistent with the BL Lac object TXS 2241+406 (a.k.a.3FGL J2244.1+4057, Acero et al. 2015, arXiv:1501.02003) at RA=341.05305 deg, Dec=40.95378 deg (J2000, Beasley et al. 2002, ApJS, 141, 13) with redshift z=1.171 (Shaw et al. 2012, ApJ, 748, 49).

  2. Discovery of VHE gamma-ray emission from the BL Lac object B3 2247+381 with the MAGIC telescopes

    CERN Document Server

    Aleksić, J; Antonelli, L A; Antoranz, P; Asensio, M; Backes, M; Barrio, J A; Bastieri, D; González, J Becerra; Bednarek, W; Berdyugin, A; Berger, K; Bernardini, E; Biland, A; Blanch, O; Bock, R K; Boller, A; Bonnoli, G; Tridon, D Borla; Braun, I; Bretz, T; Cañellas, A; Carmona, E; Carosi, A; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Cossio, L; Covino, S; Dazzi, F; De Angelis, A; De Caneva, G; del Pozo, E De Cea; De Lotto, B; Mendez, C Delgado; Ortega, A Diago; Doert, M; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Elsaesser, D; Ferenc, D; Fonseca, M V; Font, L; Fruck, C; López, R J García; Garczarczyk, M; Garrido, D; Giavitto, G; Godinović, N; Hadasch, D; Häfner, D; Herrero, A; Hildebrand, D; Höhne-Mönch, D; Hose, J; Hrupec, D; Huber, B; Jogler, T; Kellermann, H; Klepser, S; Krähenbühl, T; Krause, J; La Barbera, A; Lelas, D; Leonardo, E; Lindfors, E; Lombardi, S; López, M; López-Oramas, A; Lorenz, E; Makariev, M; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Mariotti, M; Martínez, M; Mazin, D; Meucci, M; Miranda, J M; Mirzoyan, R; Miyamoto, H; Moldón, J; Moralejo, A; Munar-Adrover, P; Nieto, D; Nilsson, K; Orito, R; Oya, I; Paneque, D; Paoletti, R; Pardo, S; Paredes, J M; Partini, S; Pasanen, M; Pauss, F; Perez-Torres, M A; Persic, M; Peruzzo, L; Pilia, M; Pochon, J; Prada, F; Moroni, P G Prada; Prandini, E; Puljak, I; Reichardt, I; Reinthal, R; Rhode, W; Ribó, M; Rico, J; Rügamer, S; Saggion, A; Saito, K; Saito, T Y; Salvati, M; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Shayduk, M; Shore, S N; Sillanpää, A; Sitarek, J; Snidaric, I; Sobczynska, D; Spanier, F; Spiro, S; Stamatescu, V; Stamerra, A; Steinke, B; Storz, J; Strah, N; Surić, T; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzić, T; Tescaro, D; Teshima, M; Tibolla, O; Torres, D F; Treves, A; Uellenbeck, M; Vankov, H; Vogler, P; Wagner, R M; Weitzel, Q; Zabalza, V; Zandanel, F; Zanin, R; Kadenius, V; Weidinger, M; Buson, S

    2012-01-01

    We study the non-thermal jet emission of the BL Lac object B3 2247+381 during a high optical state. The MAGIC telescopes observed the source during 13 nights between September 30th and October 30th 2010, collecting a total of 14.2 hours of good quality very high energy (VHE) $\\gamma$-ray data. Simultaneous multiwavelength data was obtained with X-ray observations by the Swift satellite and optical R-band observations at the KVA-telescope. We also use high energy $\\gamma$-ray (HE, 0.1 GeV-100 GeV) data from the Fermi satellite. The BL Lac object B3 2247+381 (z=0.119) was detected, for the first time, at VHE $\\gamma$-rays at a statistical significance of 5.6 $\\sigma$. A soft VHE spectrum with a photon index of -3.2 $\\pm$ 0.6 was determined. No significant short term flux variations were found. We model the spectral energy distribution using a one-zone SSC-model, which can successfully describe our data.

  3. Quasi-simultaneous observations of the BL Lac object MK 501 in X-ray, UV, visible, IR and radio frequencies

    Science.gov (United States)

    Kondo, D. M.; Worrall, D. M.; Mushotzky, R. F.; Hackney, R. L.; Hackney, K. H.; Oke, J. B.; Yee, H.; Neugebauer, G.; Matthews, K.; Feldman, P. A.

    1980-01-01

    Quasi-simultaneous observations of the BL Lacertae (Lac) objects MK 501 were performed for the first time at X-ray, ultraviolet, visible, infrared, and radio frequencies. The observed spectral slope from the X-ray to UV regions is positive and continuous, but that from the mid UV to visible light region becomes gradually flat and possibly turns down toward lower frequencies; the optical radio emission can not be accounted for by a single power law. Several theoretical models were considered for the emission mechanism. A quantitative comparison was performed with the synchrotron-self-Compton model; the total spectrum is found consistent with this model. The spectrum from visible light to X-ray is consistent with synchrotron radiation or with inverse-Compton scattering by a hot thermal cloud of electrons. The continuity of the spectral slope from X-ray to UV implied by the current data suggests that the previous estimates of the total luminosity of this BL Lac object is underestimated by a factor of about three or four.

  4. X-ray and TeV Gamma-Ray Emission from Parallel Electron-Positron or Electron-Proton Beams in BL Lac Objects

    CERN Document Server

    Krawczynski, H

    2006-01-01

    In this paper we discuss models of the X-rays and TeV gamma-ray emission from BL Lac objects based on parallel electron-positron or electron-proton beams that form close to the central black hole owing to the strong electric fields generated by the accretion disk and possibly also by the black hole itself. Fitting the energy spectrum of the BL Lac object Mrk 501, we obtain tight constrains on the beam properties. Launching a sufficiently energetic beam requires rather strong magnetic fields close to the black hole 100-1000 G. However, the model fits imply that the magnetic field in the emission region is only 0.02 G. Thus, the particles are accelerated close to the black hole and propagate a considerable distance before instabilities trigger the dissipation of energy through synchrotron and self-Compton emission. We discuss various approaches to generate enough power to drive the jet and, at the same time, to accelerate particles to 20 TeV energies. Although the parallel beam model has its own problems, it ex...

  5. Swift XRT and UVOT deep observations of the high energy peaked BL Lac object PKS 0548-322 close to its brightest state

    CERN Document Server

    Perri, M; Giommi, P; Massaro, E; Nesci, R; Tramacere, A; Capalbi, M; Cusumano, G; Chincarini, G; Tagliaferri, G; Burrows, D N; Vanden Berk, D E; Gehrels, N; Sambruna, R M

    2006-01-01

    We present the results of a spectral analysis of 5 Swift XRT and UVOT observations of the BL Lac object PKS 0548-322 carried out over the period April-June 2005. The X-ray flux of this high energy peaked BL Lac (HBL) source was found to be approximately constant at a level of F(2-10 keV) ~ 4x10^-11 erg cm^-2 s^-1, a factor of 2 brighter than when observed by BeppoSAX in 1999 and close to the maximum intensity reported in the Einstein Slew Survey. The very good statistics obtained in the 0.3-10 keV Swift X-ray spectrum allowed us to detect highly significant deviations from a simple power law spectral distribution. A log-parabolic model describes well the X-ray data and gives a best fit curvature parameter of 0.18 and peak energy in the Spectral Energy Distribution of about 2 keV. The UV spectral data from Swift UVOT join well with a power law extrapolation of the soft X-ray data points suggesting that the same component is responsible for the observed emission in the two bands. The combination of synchrotron ...

  6. On the redshift of the very high energy {\\gamma}-ray BL Lac object S2 0109+22

    CERN Document Server

    Paiano, Simona; Falomo, Renato; Scarpa, Riccardo; Treves, Aldo

    2016-01-01

    The determination of the redshift of extragalactic gamma ray sources is of fundamental importance for the interpretation of their emission models and extragalactic population studies, AGN classification schemes, and to study the interaction with the extragalactic background light. Here we focus on the BL Lac S2 0109+22, recently detected at very high energies. We obtained a high signal-to-noise optical spectrum at Gran Telescopio Canarias for the source over the spectral range 4000-10000 Angstrom, to search for spectral features of the host galaxy and/or of the nuclear source and it was compared with previous observations in order to confirm and/or dispute its redshift determination. We find the S2 0109+22 optical spectrum is well represented by a power law continuum without any absorption or emission feature of Equivalent Width >0.1 Angstrom. Based on the new optical spectrum we are able to set a redshift lower limit z>0.35, assuming the source is hosted by a massive elliptical galaxy typical for this class ...

  7. A low density of the Extragalactic Background Light revealed by the H.E.S.S. spectra of the BLLac objects 1ES 1101-232 and H 2356-309

    CERN Document Server

    Costamante, L

    2006-01-01

    The unexpectedly hard spectra measured by HESS for the BLLacs 1ES 1101-232 and H 2356-309 has allowed an upper limit on the Extragalactic Background Light (EBL) to be derived in the optical/near-infrared range, which is very close to the lower limit given by the resolved galaxy counts. This result seems to exclude a large contribution to the EBL from other sources (e.g. Population III stars) and indicates that the intergalactic space is more transparent to gamma-rays than previously thought. A brief discussion of EBL absorption effects on blazar spectra and further observational tests to check this conclusion are presented, including the selection of new candidates for observations with Cherenkov telescopes.

  8. Extreme BL Lacs: probes for cosmology and UHECR candidates

    CERN Document Server

    Tavecchio, F

    2015-01-01

    High-energy observations of extreme BL Lac objects, such as 1ES0229+200 or 1ES 0347-121, recently focused interest both for blazar and jet physics and for the implication on the extragalactic background light and intergalactic magnetic field estimate. Moreover, their enigmatic properties have been interpreted in a scenario in which their primary high- energy output is through a beam of high-energy hadrons. However, despite their possible important role in all these topics, the number of these extreme highly peaked BL Lac objects (EHBL) is still rather small. Aiming at increase their number, we selected a group of EHBL candidates considering those undetected (or only barely detected) by the LAT onboard Fermi and characterized by a high X-ray versus radio flux ratio. We assembled the multi-wavelength spectral energy distribution of the resulting 9 sources, using available archival data of Swift, GALEX, and Fermi satellites, confirming their nature. Through a simple one-zone synchrotron self-Compton model we est...

  9. Fermi and Swift observations of a rapid flare in the BL Lac object SDSS J084411.67+531250.7 (NVSS J084411+531250)

    Science.gov (United States)

    Ciprini, Stefano

    2015-04-01

    The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux from a source positionally consistent with the optically-selected and polarized (Smith et al. 2007, ApJ, 663, 118) BL Lac object SDSS J084411.67+531250.7 (also known as NVSS J084411+531250, BZB J0844+5312, and 3FGL J0843.9+5311, Acero et al. 2015, arXiv:1501.02003), with optical counterpart coordinates (J2000.0) R.A.: 131.04872 deg, Dec.: 53.21407 deg (Adelman-McCarthy et. al 2008, ApJS, 175, 297).

  10. Non-radial motion in the TeV blazar S5 0716+714 The pc-scale kinematics of a BL Lac Object

    CERN Document Server

    Britzen, S; Witzel, A; Agudo, I; Aller, M F; Aller, H D; Karouzos, M; Eckart, A; Zensus, J A; 10.1051/0004-6361/200810875

    2010-01-01

    For the BL Lac object S5 0716+714 conflicting apparent velocities of jet component motion have been reported in the literature. This object is an intra-day variable source and suited to investigate a possible correlation between kinematic properties and flux-density variability on different timescales. We (re-)analyze 50 VLBI observations obtained with the VLBA at 5 different frequencies (5 to 43 GHz) between 1992.73 and 2006.32. We analyze the jet component motion in detail taking care not only to account for motion in the radial but also in the orthogonal direction. We study the evolution of the jet ridge line and search for correlations between radio band light curves and the kinematic properties of the jet components. We present an alternative kinematic scenario for jet component motion in S5 0716+714 with apparent stationarity of jet components (with regard to their core separation) with time. Jet components, however, do seem to move significantly non-radially with regard to their position angle and in a...

  11. Optical and radio variability of the BL Lac object AO 0235+16 a possible 5-6 year periodicity

    CERN Document Server

    Raiteri, C M; Aller, H D; Aller, M F; Heidt, J; Kurtanidze, O M; Lanteri, L; Maesano, M; Massaro, E; Montagni, F; Nesci, R; Nilsson, K; Nikolashvili, M G; Nurmi, P; Ostorero, L; Pursimo, T; Rekola, R; Sillanpää, A; Takalo, L O; Terasranta, H; Tosti, G; Balonek, T J; Feldt, M; McGrath, E J; Heines, A; Heisler, C A; Hu, J; Kidger, M; Mattox, J R; Pati, A K; Robb, R; Sadun, A C; Shastri, P; Wagner, S J; Wei, J; Wu, X

    2001-01-01

    New optical and radio data on the BL Lacertae object AO 0235+16 have been collected in the last four years by a wide international collaboration, which confirm the intense activity of this source. The optical data also include the results of the Whole Earth Blazar Telescope (WEBT) first-light campaign organized in November 1997. The optical spectrum is observed to basically steepen when the source gets fainter. We have investigated the existence of typical variability time scales and of possible correlations between the optical and radio emissions by means of visual inspection, Discrete Correlation Function analysis, and Discrete Fourier Transform technique. The major radio outbursts are found to repeat quasi-regularly with a periodicity of about 5.7 years; this period is also in agreement with the occurrence of some of the major optical outbursts, but not all of them.

  12. MULTIWAVELENGTH OBSERVATIONS AND MODELING OF 1ES 1959+650 IN A LOW FLUX STATE

    Energy Technology Data Exchange (ETDEWEB)

    Aliu, E.; Errando, M. [Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States); Archambault, S. [Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada); Arlen, T.; Aune, T. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Beilicke, M.; Bugaev, V.; Dickherber, R. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Benbow, W. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Bird, R.; Collins-Hughes, E. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Boettcher, M. [Astrophysical Institute, Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States); Bouvier, A. [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States); Byrum, K. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Cesarini, A.; Connolly, M. P. [School of Physics, National University of Ireland Galway, University Road, Galway (Ireland); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Cui, W. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Duke, C. [Department of Physics, Grinnell College, Grinnell, IA 50112-1690 (United States); Dumm, J. [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); and others

    2013-09-20

    We report on the VERITAS observations of the high-frequency peaked BL Lac object 1ES 1959+650 in the period 2007-2011. This source is detected at TeV energies by VERITAS at 16.4 standard deviation ({sigma}) significance in 7.6 hr of observation in a low flux state. A multiwavelength spectral energy distribution (SED) is constructed from contemporaneous data from VERITAS, Fermi-LAT, RXTE PCA, and Swift UVOT. Swift XRT data is not included in the SED due to a lack of simultaneous observations with VERITAS. In contrast to the orphan {gamma}-ray flare exhibited by this source in 2002, the X-ray flux of the source is found to vary by an order of magnitude, while other energy regimes exhibit less variable emission. A quasi-equilibrium synchrotron self-Compton model with an additional external radiation field is used to describe three SEDs corresponding to the lowest, highest, and average X-ray states. The variation in the X-ray spectrum is modeled by changing the electron injection spectral index, with minor adjustments of the kinetic luminosity in electrons. This scenario produces small-scale flux variability of the order of {approx}< 2 in the high energy (E > 1 MeV) and very high energy (E > 100 GeV) {gamma}-ray regimes, which is corroborated by the Fermi-LAT, VERITAS, and Whipple 10 m telescope light curves.

  13. The WEBT campaign on the BL Lac object PG 1553+113 in 2013. An analysis of the enigmatic synchrotron emission

    CERN Document Server

    Raiteri, C M; Villata, M; Larionov, V M; Acosta-Pulido, J A

    2015-01-01

    A multifrequency campaign on the BL Lac object PG 1553+113 was organized by the Whole Earth Blazar Telescope (WEBT) in 2013 April-August, involving 19 optical, two near-IR, and three radio telescopes. The aim was to study the source behaviour at low energies during and around the high-energy observations by the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes in April-July. We also analyse the UV and X-ray data acquired by the Swift and XMM-Newton satellites in the same period. The WEBT and satellite observations allow us to detail the synchrotron emission bump in the source spectral energy distribution (SED). In the optical we found a general bluer-when-brighter trend. The X-ray spectrum remained stable during 2013, but a comparison with previous observations suggests that it becomes harder when the X-ray flux increases. The long XMM-Newton exposure reveals a curved X-ray spectrum. In the SED, the XMM-Newton data show a hard near-UV spectrum, while Swift data display a softer shape that is co...

  14. Discovery of VHE \\gamma-ray emission and multi-wavelength observations of the BL Lac object 1RXS J101015.9-311909

    CERN Document Server

    Abramowski, A; Aharonian, F; Akhperjanian, A G; Anton, G; Balzer, A; Barnacka, A; Becherini, Y; Becker, J; Bernlöhr, K; Birsin, E; Biteau, J; Bochow, A; Boisson, C; Bolmont, J; Bordas, P; Brucker, J; Brun, F; Brun, P; Bulik, T; Büsching, I; Carrigan, S; Casanova, S; Cerruti, M; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Cologna, G; Conrad, J; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Egberts, K; Eger, P; Espigat, P; Fallon, L; Fegan, S; Feinstein, F; Fernandes, M V; Fiasson, A; Fontaine, G; Förster, A; Füßling, M; Gallant, Y A; Gast, H; Gérard, L; Gerbig, D; Giebels, B; Glicenstein, J F; Glück, B; Göring, D; Häffner, S; Hague, J D; Hahn, J; Hampf, D; Harris, J; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hillert, A; Hinton, J A; Hofmann, W; Hofverberg, P; Holler, M; Horns, D; Jacholkowska, A; de Jager, O C; Jahn, C; Jamrozy, M; Jung, I; Kastendieck, M A; Katarzyński, K; Katz, U; Kaufmann, S; Keogh, D; Khélifi, B; Klochkov, D; Kluźniak, W; Kneiske, T; Komin, Nu; Kosack, K; Kossakowski, R; Krayzel, F; Laffon, H; Lamanna, G; Lenain, J -P; Lennarz, D; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Masbou, J; Maxted, N; Mayer, M; McComb, T J L; Medina, M C; Méhault, J; Moderski, R; Mohamed, M; Moulin, E; Naumann, C L; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nekrassov, D; Nguyen, N; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Wilhelmi, E de Oña; Opitz, B; Ostrowski, M; Oya, I; Panter, M; Arribas, M Paz; Pekeur, N W; Pelletier, G; Perez, J; Petrucci, P -O; Peyaud, B; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raue, M; Rayner, S M; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Sahakian, V; Sanchez, D A; Santangelo, A; Schlickeiser, R; Schulz, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Sheidaei, F; Skilton, J L; Sol, H; Spengler, G; Stawarz, Ł; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Szostek, A; Tavernet, J -P; Terrier, R; Tluczykont, M; Valerius, K; van Eldik, C; Vasileiadis, G; Venter, C; Viana, A; Vincent, P; Völk, H J; Volpe, F; Vorobiov, S; Vorster, M; Wagner, S J; Ward, M; White, R; Wierzcholska, A; Zacharias, M; Zajczyk, A; Zdziarski, A A; Zech, A; Zechlin, H -S

    2012-01-01

    1RXS J101015.9-311909 is a galaxy located at a redshift of z=0.14 hosting an active nucleus belonging to the class of bright BL Lac objects. Observations at high (HE, E > 100 MeV) and very high (VHE, E > 100 GeV) energies provide insights into the origin of very energetic particles present in such sources and the radiation processes at work. We report on results from VHE observations performed between 2006-10 with H.E.S.S. H.E.S.S. data have been analysed with enhanced analysis methods, making the detection of faint sources more significant. VHE emission at a position coincident with 1RXS J101015.9-311909 is detected with H.E.S.S. for the first time. In a total good-quality livetime of about 49 h, we measure 263 excess counts, corresponding to a significance of 7.1\\sigma. The photon spectrum above 0.2 TeV can be described by a power-law with a photon index of \\Gamma\\ = 3.08\\pm0.42_{stat}\\pm0.20_{sys}. The integral flux above 0.2 TeV is about 0.8% of the flux of the Crab nebula and shows no significant variabi...

  15. Discovery of very high energy gamma-ray emission from the BL Lac object PKS 0301-243 with H.E.S.S

    CERN Document Server

    Abramowski, A; Aharonian, F; Ait, F; Akhperjanian, A G; Angüner, E; Anton, G; Balenderan, S; Balzer, A; Barnacka, A; Becherini, Y; Becker, J; Bernlöhr, K; Birsin, E; Bissaldi, E; Biteau, J; Böttcher, M; Boisson, C; Bolmont, J; Bordas, P; Brucker, J; Brun, F; Brun, P; Bulik, T; Carrigan, S; Casanova, S; Cerruti, M; Chadwick, P M; Chalme-Calvet, R; Chaves, R C G; Cheesebrough, A; Chrétien, M; Colafrancesco, S; Cologna, G; Conrad, J; Couturier, C; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; deWilt, P; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Edwards, T; Egberts, K; Eger, P; Espigat, P; Farnier, C; Fegan, S; Feinstein, F; Fernandes, M V; Fernandez, D; Fiasson, A; Fontaine, G; Förster, A; Füssling, M; Gajdus, M; Gallant, Y A; Garrigoux, T; Giebels, B; Glicenstein, J F; Grondin, M -H; Grudzìnska, M; Häffner, S; Hague, J D; Hahn, J; Harris, J; Heinzelmann, G; Henri, G; Hermann, G; Hervet, O; Hillert, A; Hinton, J A; Hofmann, W; Hofverberg, P; Holler, M; Horns, D; Jacholkowska, A; Jahn, C; Jamrozy, M; Janiak, M; Jankowsky, F; Jung, I; Kastendieck, M A; Katarzyński, K; Katz, U; Kaufmann, S; Khélifi, B; Kieffer, M; Klepser, S; Klochkov, D; Kluźniak, W; Kneiske, T; Kolitzus, D; Komin, Nu; Kosack, K; Krakau, S; Krayzel, F; Krüger, P P; Laffon, H; Lamanna, G; Lefaucheur, J; Lemoine-Goumard, M; Lenain, J -P; Lennarz, D; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Marx, R; Maurin, G; Maxted, N; Mayer, M; McComb, T J L; Medina, M C; Méhault, J; Menzler, U; Meyer, M; Moderski, R; Mohamed, M; Moulin, E; Murach, T; Naumann, C L; de Naurois, M; Nedbal, D; Niemiec, J; Nolan, S J; Oakes, L; Ohm, S; Wilhelmi, E de Oña; Opitz, B; Ostrowski, M; Oya, I; Panter, M; Parsons, R D; Arribas, M Paz; Pekeur, N W; Pelletier, G; Perez, J; Petrucci, P -O; Peyaud, B; Pita, S; Poon, H; Pühlhofer, G; Punch, M; Quirrenbach, A; Raab, S; Raue, M; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Sahakian, V; Sanchez, D A; Santangelo, A; Schlickeiser, R; Schüssler, F; Schulz, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Sol, H; Spengler, G; Spies, F; Stawarz, L; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Szostek, A; Tavernet, J -P; Terrier, R; Tluczykont, M; Trichard, C; Valerius, K; van Eldik, C; Vasileiadis, G; Venter, C; Viana, A; Vincent, P; Völk, H J; Volpe, F; Vorster, M; Wagner, S J; Wagner, P; Ward, M; Weidinger, M; Weitzel, Q; White, R; Wierzcholska, A; Willmann, P; Wörnlein, A; Wouters, D; Zacharias, M; Zajczyk, A; Zdziarski, A A; Zech, A; Zechlin, H -S

    2013-01-01

    The active galactic nucleus PKS 0301-243 (z=0.266) is a high-synchrotron-peaked BL Lac object that is detected at high energies (HE, 100 MeV 100 GeV) by the High Energy Stereoscopic System (H.E.S.S.) from observations between September 2009 and December 2011 for a total live time of 34.9 hours. Gamma rays above 200 GeV are detected at a significance of 9.4{\\sigma}. A hint of variability at the 2.5{\\sigma} level is found. An integral flux I(E > 200 GeV) = (3.3 +/- 1.1_stat +/- 0.7_syst)e-12 ph cm^-2s^-1 and a photon index {\\Gamma} = 4.6 +/- 0.7_stat +/- 0.2_syst are measured. Multi-wavelength light curves in HE, X-ray and optical bands show strong variability, and a minimal variability timescale of eight days is estimated from the optical light curve. A single-zone leptonic synchrotron self-Compton scenario satisfactorily reproduces the multi-wavelength data. In this model, the emitting region is out of equipartition and the jet is particle dominated. Because of its high redshift compared to other sources obse...

  16. Observations of the high-energy peaked BL Lac object H 1426+428 with the solar tower atmospheric Cherenkov effect experiment

    Science.gov (United States)

    Mueller, Carsten

    The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) was an atmospheric Cherenkov telescope operational until June 2007, which detected cosmic gamma rays by means of the wavefront-sampling technique. Using 64 of the large heliostats available at the National Solar Thermal Test Facility (NSTTF) near Albuquerque, New Mexico, its total mirror area of 2378 m 2 allowed it to achieve energy thresholds between 150 and 200 GeV. Following a review of the field of gamma-ray astrophysics and Active Galactic Nuclei, this work provides a detailed description of the detector, along with an introduction to simulation and data analysis techniques. During the springs of 2003 and 2004, STACEE observed the High-Energy-Peaked BL Lac object H 1426+428, an established emitter of gamma rays in the TeV energy range. A full analysis of these data reveals that STACEE did not detect a statistically significant gamma-ray excess from H 1426+428 in either data set. With the help of detailed detector simulations, upper limits on the integrated gamma ray fluxes, phi int, at the 95% confidence level are obtained for both observing seasons: phi int(E > 163 GeV) 165 GeV) < 0.78·10-6 m-2 s-1 for 2003 and 2004, respectively. The derived upper limits are discussed in the context of the results obtained by other gamma-ray observatories.

  17. Location of the Gamma-Ray Flaring Emission in the Parse-Scale Jet of the BL Lac Object AO 0235+164

    CERN Document Server

    Agudo, Ivan; Jorstad, Svetlana G; Larionov, Valeri M; Gomez, Jose L; Lahteenmaki, Anne; Smith, Paul S; Nilsson, Kari; Readhead, Anthony C S; Aller, Margo F; Heidt, Jochen; Gurwell, Mark; Thum, Clemens; Wehrle, Ann E; Kurtanidze, Omar M

    2011-01-01

    We locate the gamma-ray and lower frequency emission in flares of the BL Lac object AO 0235+164 at >12pc in the jet of the source from the central engine. We employ time-dependent multi-spectral-range flux and linear polarization monitoring observations, as well as ultra-high resolution (~0.15 milliarcsecond) imaging of the jet structure at lambda=7mm. The time coincidence in the end of 2008 of the propagation of the brightest superluminal feature detected in AO 0235+164 (Qs) with an extreme multi-spectral-range (gamma-ray to radio) outburst, and an extremely high optical and 7mm (for Qs) polarization degree provides strong evidence supporting that all these events are related. This is confirmed at high significance by probability arguments and Monte-Carlo simulations. These simulations show the unambiguous correlation of the gamma-ray flaring state in the end of 2008 with those in the optical, millimeter, and radio regime, as well as the connection of a prominent X-ray flare in October 2008, and of a series ...

  18. Perplexing correlations between Gamma-ray emission and parsec-scale jet orientation variations in the BL Lac object S5 0716+714

    CERN Document Server

    Rani, B; Marscher, A P; Jorstad, S G; Hodgson, J A; Fuhrmann, L; Zensus, J A

    2015-01-01

    The analysis of $\\gamma$-ray flux variability along with the parsec-scale jet kinematics suggests that the high-energy radiation in the BL Lac object S5 0716+714 has a significant correlation with the mm-VLBI core flux density and with the local orientation of the inner jet flow. For the first time in any blazar, we report a significant correlation between the $\\gamma$-ray flux variations and the variations in the local orientation of the jet outflow (position angle). We find that the $\\gamma$-ray flux variations lead the 7~mm VLBI core flux variations by 82$\\pm$32~days, which suggests that the high-energy emission in S5 0716+714 is coming from a region located 3.8$\\pm$1.9~parsecs closer to the central black hole than the "core" seen on the mm-VLBI images. The results imply a strong physical and casual connection between $\\gamma$-ray emission and the inner jet morphology in the source.

  19. Constraining the parameter space of the one-zone synchrotron-self-Compton model for GeV-TeV detected BL Lac objects

    CERN Document Server

    Cerruti, Matteo; Zech, Andreas

    2013-01-01

    The one-zone synchrotron-self-Compton (SSC) model aims to describe the spectral energy distribution (SED) of BL Lac objects via synchrotron emission by a non-thermal population of electrons and positrons in a single homogeneous emission region, partially upscattered to gamma-rays by the particles themselves. The model is usually considered as degenerate, given that the number of free parameters is higher than the number of observables. It is thus common to model the SED by choosing a single set of values for the SSC-model parameters that provide a good description of the data, without studying the entire parameter space. We present here a new numerical algorithm which permits us to find the complete set of solutions, using the information coming from the detection in the GeV and TeV energy bands. The algorithm is composed of three separate steps: we first prepare a grid of simulated SEDs and extract from each SED the values of the observables; we then parametrize each observable as a function of the SSC param...

  20. Multi-Epoch VLBA Observations of EGRET-Detected Quasars and BL Lac Objects Superluminal Motion of Gamma-Ray Bright Blazars

    CERN Document Server

    Jorstad, S G; Mattox, J R; Wehrle, A E; Bloom, S D; Yurchenko, A V; Jorstad, Svetlana G; Marscher, Alan P; Mattox, John R; Wehrle, Ann E; Bloom, Steven D; Yurchenko, Alexei V

    2001-01-01

    We present the results of a program to monitor the structure of the radio emission in 42 $\\gamma$-ray bright blazars (31 quasars and 11 BL Lac objects) with the VLBA at 43, 22, and occasionally 15 and 8.4 GHz, over the period from November 1993 to July 1997. We determine proper motions in 33 sources and find that the apparent superluminal motions in $\\gamma$-ray sources are much faster than for the general population of bright compact radio sources. This follows the strong dependence of the $\\gamma$-ray flux on the level of relativistic beaming for both external-radiation Compton and synchrotron self-Compton emission. There is a positive correlation (correlation coefficient $r$=0.45) between the flux density of the VLBI core and the $\\gamma$-ray flux and a moderate correlation (partial correlation coefficient $r$=0.31) between $\\gamma$-ray apparent luminosity and superluminal velocities of jet components, as expected if the $\\gamma$-ray emission originates in a very compact region of the relativistic jet and ...

  1. Bright X-Ray Flares from the BL Lac Object Markarian 421, Detected with MAXI in 2010 January and February

    Science.gov (United States)

    Isobe, Naoki; Sugimori, Kousuke; Kawai, Nobuyuki; Ueda, Yoshihiro; Negoro, Hitoshi; Sugizaki, Mutsumi; Matsuoka, Masaru; Daikyuji, Arata; Eguchi, Satoshi; Hiroi, Kazuo; Ishikawa, Masaki; Ishiwata, Ryoji; Kawasaki, Kazuyoshi; Kimura, Masashi; Kohama, Mitsuhiro; Mihara, Tatehiro; Miyoshi, Sho; Morii, Mikio; Nakagawa, Yujin E.; Nakahira, Satoshi; Nakajima, Motoki; Ozawa, Hiroshi; Sootome, Tetsuya; Suzuki, Motoko; Tomida, Hiroshi; Tsunemi, Hiroshi; Ueno, Shiro; Yamamoto, Takayuki; Yamaoka, Kazutaka; Yoshida, Atsumasa; MAXI Team

    2010-12-01

    Strong X-ray flares from the blazar Mrk 421 were detected in 2010 January and February through 7-month monitoring with the MAXI GSC. The maximum 2-10 keV flux in the January and February flares was measured to be 120±10 mCrab and 164±17 mCrab, respectively; the latter is the highest among those reported from the object. A comparison of the MAXI and Swift BAT data suggests a convex X-ray spectrum with an approximated photon index of Γ ≳ 2. This spectrum is consistent with a picture that MAXI is observing near the synchrotron peak frequency. The source exhibited a spectral variation during these flares, slightly different from those in previous observations, in which the positive correlation between the flux and hardness was widely reported. By equating the halving decay timescale in the January flare, td ˜ 2.5 × 104 s, to the synchrotron cooling time, the magnetic field was evaluated to be B ˜ 4.5 × 10-2G (δ/10)-1/3, where δ is the jet beaming factor. Assuming that the light crossing time of the emission region is shorter than the doubling rise time, tr ≲ 2 × 104 s, the region size was roughly estimated as R < 6 × 1015 cm (δ/10). These results are consistent with values previously reported. For the February flare, the rise time, tr < 1.3 × 105 s, gives a loose upper limit on the size as R < 4 × 1016 cm (δ/10), although the longer decay time, td ˜ 1.4 × 105s, indicates B ˜ 1.5 × 10-2G (δ/10)-1/3, which is weaker than the previous results. This could be reconciled by invoking a scenario that this flare is a superposition of unresolved events with a shorter timescale.

  2. New constraints on the Mid-IR EBL from the HESS discovery of VHE gamma rays from 1ES 0229+200

    CERN Document Server

    Aharonian, F; Bazer-Bachi, A R; Behera, B; Beilicke, M; Benbow, W; Bernlöhr, K; Boisson, C; Bolz, O; Borrel, V; Braun, I; Brion, E; Brown, A M; Buhler, R; Bulik, T; Büsching, I; Boutelier, T; Carrigan, S; Chadwick, P M; Chounet, L M; Clapson, A C; Coignet, G; Cornils, R; Costamante, L; Dalton, M; Degrange, B; Dickinson, H J; Djannati-Atai, A; Domainko, W; O'Connor-Drury, L; Dubois, F; Dubus, G; Dyks, J; Egberts, K; Emmanoulopoulos, D; Espigat, P; Farnier, C; Feinstein, F; Fiasson, A; Förster, A; Fontaine, G; Funk, Seb; Fussling, M; Gallant, Y A; Giebels, B; Glicenstein, J F; Glück, B; Goret, P; Hadjichristidis, C; Hauser, D; Hauser, M; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hoffmann, A; Hofmann, W; Holleran, M; Hoppe, S; Horns, D; Jacholkowska, A; De Jager, O C; Jung, I; Katarzynski, K; Kendziorra, E; Kerschhaggl, M; Khelifi, B; Keogh, D; Komin, Nu; Kosack, K; Lamanna, G; Latham, I J; Lemiere, A; Lemoine-Goumard, M; Lenain, J P; Lohse, T; Martin, J M; Martineau-Huynh, O; Marcowith, A; Masterson, C; Maurin, D; Maurin, G; McComb, T J L; Moderski, R; Moulin, E; De Naurois, Mathieu; Nedbal, D; Nolan, S J; Ohm, S; Olive, J P; de Ona Wilhelmi, E; Orford, K J; Osborne, J L; Ostrowski, M; Panter, M; Pedaletti, G; Pelletier, G; Petrucci, P O; Pita, S; Pühlhofer, G; Punch, M; Ranchon, S; Raubenheimer, B C; Raue, M; Rayner, S M; Renaud, M; Ripken, J; Rob, L; Rolland, L; Rosier-Lees, S; Rowell, G; Rudak, B; Ruppel, J; Sahakian, V V; Santangelo, A; Schlickeiser, R; Schock, F; Schroder, R; Schwanke, U; Schwarzburg, S; Schwemmer, S; Shalchi, A; Sol, H; Spangler, D; Stawarz, L; Steenkamp, R; Stegmann, C; Superina, G; Tam, P H; Tavernet, J P; Terrier, R; Van Eldik, C; Vasileiadis, G; Venter, C; Vialle, J P; Vincent, P; Vivier, M; Völk, H J; Volpe, F; Wagner, S J; Ward, M; Zdziarski, A A; Zech, A

    2007-01-01

    AIMS: To investigate the very high energy (VHE: >100 GeV) gamma-ray emission from the high-frequency peaked BL Lac 1ES 0229+200. METHODS: Observations of 1ES 0229+200 at energies above 580 GeV were performed with the High Energy Stereoscopic System (HESS) in 2005 and 2006. RESULTS: 1ES 0229+200 is discovered by HESS to be an emitter of VHE photons. A signal is detected at the 6.6 sigma level in the HESS observations (41.8 h live time). The integral flux above 580 GeV is (9.4 +- 1.5 {stat} +- 1.9 {syst}) x 10^{-13} cm^{-2} s^{-1}, corresponding to ~1.8% of the flux observed from the Crab Nebula. The data show no evidence for significant variability on any time scale. The observed spectrum is characterized by a hard power law (Gamma = 2.50 +- 0.19 {stat} +- 0.10 {syst}) from 500 GeV to ~15 TeV. CONCLUSIONS: The high-energy range and hardness of the observed spectrum, coupled with the object's relatively large redshift (z=0.1396), enable the strongest constraints so far on the density of the Extragalactic Backgr...

  3. Discovery of very high energy gamma-ray emission from the blazar 1ES 1727+502 with the MAGIC Telescopes

    CERN Document Server

    Aleksić, J; Antoranz, P; Asensio, M; Backes, M; de Almeida, U Barres; Barrio, J A; González, J Becerra; Bednarek, W; Berger, K; Bernardini, E; Biland, A; Blanch, O; Bock, R K; Boller, A; Bonnefoy, S; Bonnoli, G; Tridon, D Borla; Borracci, F; Bretz, T; Carmona, E; Carosi, A; Fidalgo, D Carreto; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Cossio, L; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Caneva, G; De Lotto, B; Mendez, C Delgado; Doert, M; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Eisenacher, D; Elsaesser, D; Farina, E; Ferenc, D; Fonseca, M V; Font, L; Fruck, C; López, R J García; Garczarczyk, M; Terrats, D Garrido; Gaug, M; Giavitto, G; Godinović, N; Muñoz, A González; Gozzini, S R; Hadamek, A; Hadasch, D; Häfner, D; Herrero, A; Hose, J; Hrupec, D; Idec, W; Jankowski, F; Kadenius, V; Klepser, S; Knoetig, M L; Krähenbühl, T; Krause, J; Kushida, J; La Barbera, A; Lelas, D; Lewandowska, N; Lindfors, E; Lombardi, S; López, M; López-Coto, R; López-Oramas, A; Lorenz, E; Lozano, I; Makariev, M; Mallot, K; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martínez, M; Masbou, J; Mazin, D; Meucci, M; Miranda, J M; Mirzoyan, R; Moldón, J; Moralejo, A; Munar-Adrover, P; Nakajima, D; Niedzwiecki, A; Nilsson, K; Nowak, N; Orito, R; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, J M; Partini, S; Persic, M; Prada, F; Moroni, P G Prada; Prandini, E; Puljak, I; Reichardt, I; Reinthal, R; Rhode, W; Ribó, M; Rico, J; Rügamer, S; Saggion, A; Saito, K; Saito, T Y; Salvati, M; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Shore, S N; Sillanpää, A; Sitarek, J; Snidaric, I; Sobczynska, D; Spanier, F; Spiro, S; Stamatescu, V; Stamerra, A; Steinke, B; Storz, J; Sun, S; Surić, T; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzić, T; Tescaro, D; Teshima, M; Tibolla, O; Torres, D F; Toyama, T; Treves, A; Uellenbeck, M; Vogler, P; Wagner, R M; Weitzel, Q; Zandanel, F; Zanin, R

    2013-01-01

    Motivated by the Costamante & Ghisellini (2002) predictions we investigated if the blazar 1ES 1727+502 (z=0.055) is emitting very high energy (VHE, E>100 GeV) gamma rays. We observed the BL Lac object 1ES 1727+502 in stereoscopic mode with the two MAGIC telescopes during 14 nights between May 6th and June 10th 2011, for a total effective observing time of 12.6 hours. For the study of the multiwavelength spectral energy distribution (SED) we use simultaneous optical R-band data from the KVA telescope, archival UV/optical and X-ray observations by instruments UVOT and XRT on board of the Swift satellite and high energy (HE, 0.1 GeV - 100 GeV) gamma-ray data from the Fermi-LAT instrument. We detect, for the first time, VHE gamma-ray emission from 1ES 1727+502 at a statistical significance of 5.5 sigma. The integral flux above 150 GeV is estimated to be (2.1\\pm0.4)% of the Crab Nebula flux and the de-absorbed VHE spectrum has a photon index of (2.7\\pm0.5). No significant short-term variability was found in an...

  4. Discovery of VHE gamma-rays from the blazar 1ES 1215+303 with the MAGIC Telescopes and simultaneous multi-wavelength observations

    CERN Document Server

    Aleksić, J; Antonelli, L A; Antoranz, P; Asensio, M; Backes, M; de Almeida, U Barres; Barrio, J A; Bastieri, D; González, J Becerra; Bednarek, W; Berger, K; Bernardini, E; Biland, A; Blanch, O; Bock, R K; Boller, A; Bonnoli, G; Tridon, D Borla; Bretz, T; Cañellas, A; Carmona, E; Carosi, A; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Cossio, L; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Caneva, G; del Pozo, E De Cea; De Lotto, B; Mendez, C Delgado; Ortega, A Diago; Doert, M; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Eisenacher, D; Elsaesser, D; Ferenc, D; Fonseca, M V; Font, L; Fruck, C; López, R J García; Garczarczyk, M; Terrats, D Garrido; Giavitto, G; Godinović, N; Muñoz, A González; Gozzini, S R; Hadasch, D; Häfner, D; Herrero, A; Hildebrand, D; Hose, J; Hrupec, D; Huber, B; Jankowski, F; Jogler, T; Kadenius, V; Kellermann, H; Klepser, S; Krähenbühl, T; Krause, J; La Barbera, A; Lelas, D; Leonardo, E; Lewandowska, N; Lindfors, E; Lombardi, S; López, M; López-Coto, R; López-Oramas, A; Lorenz, E; Makariev, M; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Mariotti, M; Martínez, M; Mazin, D; Meucci, M; Miranda, J M; Mirzoyan, R; Moldón, J; Moralejo, A; Munar-Adrover, P; Niedzwiecki, A; Nieto, D; Nilsson, K; Nowak, N; Orito, R; Paiano, S; Paneque, D; Paoletti, R; Pardo, S; Paredes, J M; Partini, S; Perez-Torres, M A; Persic, M; Pilia, M; Pochon, J; Prada, F; Moroni, P G Prada; Prandini, E; Gimenez, I Puerto; Puljak, I; Reichardt, I; Reinthal, R; Rhode, W; Ribó, M; Rico, J; Rügamer, S; Saggion, A; Saito, K; Saito, T Y; Salvati, M; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Shore, S N; Sillanpää, A; Sitarek, J; Snidaric, I; Sobczynska, D; Spanier, F; Spiro, S; Stamatescu, V; Stamerra, A; Steinke, B; Storz, J; Strah, N; Sun, S; Surić, T; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzić, T; Tescaro, D; Teshima, M; Tibolla, O; Torres, D F; Treves, A; Uellenbeck, M; Vogler, P; Wagner, R M; Weitzel, Q; Zabalza, V; Zandanel, F; Zanin, R; Berdyugin, A; Buson, S; Järvelä, E; Larsson, S; Lähteenmäki, A; Tammi, J; de Lausanne, now at: Ecole polytechnique fédérale; Lausanne,; Switzerland,; Padova, supported by INFN; Energéticas, now at: Centro de Investigaciones; Tecnológicas, Medioambientales y; Madrid,; Spain,; KIPAC, now at:; Laboratory, SLAC National Accelerator; USA,; ESO, now at: Finnish Centre for Astronomy with; Turku, University of; Finland,; Observatory, Aalto University Metsähovi Radio; Metsähovintie,; Finland,; Physics, Department of; University, Stockholm; Stockholm,; Sweden,; Physics, The Oskar Klein Centre for Cosmoparticle; Stockholm,; Sweden,; Astronomy, Department of; University, Stockholm; Stockholm,; Sweden),

    2012-01-01

    Context. We present the discovery of very high energy (VHE, E > 100GeV) gamma-ray emission from the BL Lac object 1ES 1215+303 by the MAGIC telescopes and simultaneous multi-wavelength data in a broad energy range from radio to gamma-rays. Aims. We study the VHE gamma-ray emission from 1ES 1215+303 and its relation to the emissions in other wavelengths. Methods. Triggered by an optical outburst, MAGIC observed the source in January-February 2011 for 20.3 hrs. The target was monitored in the optical R-band by the KVA telescope that also performed optical polarization measurements. We triggered target of opportunity observations with the Swift satellite and obtained simultaneous and quasi-simultaneous data from the Fermi Large Area Telescope and from the Mets\\"ahovi radio telescope. We also present the analysis of older MAGIC data taken in 2010. Results. The MAGIC observations of 1ES 1215+303 carried out in January-February 2011 resulted in the first detection of the source at VHE with a statistical significanc...

  5. 1ES 0033+595 found in a very high state by INTEGRAL

    DEFF Research Database (Denmark)

    Bassani, L.; Malizia, A.; Chenevez, Jérôme;

    2014-01-01

    During recent Galactic Plane Scan survey observations (GPS, PI: A. Bazzano) performed between Dec 2, 2014 (08:47 UTC) and Dec 3, 2014 (00:26 UTC), INTEGRAL detected 1ES 0033+595 with both JEM-X and IBIS/ISGRI instruments. 1ES 0033+595 is a blazar near the Galactic plane belonging to the BL Lac type......; the source has recently been reported as one of the 50 or so blazars detected at TeV energies (Aleksic et al. 2014, http://arxiv.org/abs/1410.7059v1 ). 1ES 0033+595 was found in the combined JMX1+2 mosaic (effective exposure of 3.1 ksec, 3-10 keV band) with a flux of 20 +/-2 mCrab (3.4 x 10^-10 erg/cm2/s......) corresponding to a 10 sigma significance. It is also detected at higher energies ((in JEM-X2 only), with a flux of 21 +/-5 mCrab (or 2.5 x 10^-10 erg/cm2/s) at 4 sigma level (effective exposure of 1.2 ksec, 10-25 keV band). At even higher energies, IBIS/ISGRI found 1ES 0033+595Â at a flux level of 13.6+/-2 m...

  6. The Simultaneous Low State Spectral Energy Distribution of 1ES 2344+514 from Radio to Very High Energies

    CERN Document Server

    Longo, F; Pittori, C; Vercellone, S; Bastieri, D; Angelakis, E; Fuhrmann, L; Nestoras, I; Krichbaum, T P; Sievers, A; Antonyuk, K A; Baumgartner, W; Berduygin, A; Carini, M; Cook, K; Gehrels, N; Kadler, M; Kovalev, Yu A; Kovalev, Y Y; Krauss, F; Krimm, H A; Lähteenmäki, A; Lister, M L; Max-Moerbeck, W; Pasanen, M; Pushkarev, A B; Readhead, A C S; Richards, J L; Sainio, J; Shakhovskoy, D N; Sokolovsky, K V; Tornikoski, M; Tueller, J; Weidinger, M; Wilms, J

    2012-01-01

    [Abridged] Context. To construct and interpret the spectral energy distribution (SED) of BL Lacertae objects, simultaneous broad-band observations are mandatory. Aims. We intend to study the simultaneous broad-band emission of the high-frequency peaked BL Lac object and known TeV emitter 1ES 2344+514 by means of a pre-organised multi-wavelength campaign independently of the current flux state. By correlating the obtained light curves and describing the corresponding SEDs with state-of-the-art models we intend to derive physical parameters of the emission region. Methods. The observations were conducted during simultaneous visibility windows of MAGIC and AGILE in late 2008. The measurements were complemented by Mets\\"ahovi, RATAN-600, KVA+Tuorla, Swift and VLBA pointings. Additional coverage was provided by the ongoing long-term F-GAMMA and MOJAVE programs, the OVRO 40-m and CrAO telescopes as well as the Fermi satellite. The obtained SEDs are modelled using a one-zone as well as a self-consistent two-zone syn...

  7. MULTIWAVELENGTH OBSERVATIONS OF THE AGN 1ES 0414+009 WITH VERITAS, FERMI-LAT, SWIFT-XRT, AND MDM

    Energy Technology Data Exchange (ETDEWEB)

    Aliu, E.; Errando, M. [Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States); Archambault, S. [Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada); Arlen, T. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Aune, T.; Bouvier, A. [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States); Beilicke, M.; Bugaev, V.; Dickherber, R. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Benbow, W. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Boettcher, M. [Astrophysical Institute, Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States); Cannon, A.; Collins-Hughes, E. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Cesarini, A.; Connolly, M. P. [School of Physics, National University of Ireland Galway, University Road, Galway (Ireland); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Cui, W. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Dumm, J. [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Falcone, A. [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); Federici, S., E-mail: aw.smith@utah.edu [DESY, Platanenallee 6, 15738 Zeuthen (Germany); and others

    2012-08-20

    We present observations of the BL Lac object 1ES 0414+009 in the >200 GeV gamma-ray band by the VERITAS array of Cherenkov telescopes. 1ES 0414+009 was observed by VERITAS between 2008 January and 2011 February, resulting in 56.2 hr of good quality pointed observations. These observations resulted in a detection of 822 events from the source corresponding to a statistical significance of 6.4 standard deviations (6.4{sigma}) above the background. The source flux, showing no evidence for variability, is measured as (5.2 {+-} 1.1{sub stat} {+-} 2.6{sub sys}) Multiplication-Sign 10{sup -12} photons cm{sup -2} s{sup -1} above 200 GeV, equivalent to approximately 2% of the Crab Nebula flux above this energy. The differential photon spectrum from 230 GeV to 850 GeV is well fit by a power law with a photon index of {Gamma} = 3.4 {+-} 0.5{sub stat} {+-} 0.3{sub sys} and a flux normalization of (1.6 {+-} 0.3{sub stat} {+-} 0.8{sub sys}) Multiplication-Sign 10{sup -11} photons cm{sup -2} s{sup -1} at 300 GeV. We also present multiwavelength results taken in the optical (MDM), x-ray (Swift-XRT), and GeV (Fermi-LAT) bands and use these results to construct a broadband spectral energy distribution (SED). Modeling of this SED indicates that homogenous one-zone leptonic scenarios are not adequate to describe emission from the system, with a lepto-hadronic model providing a better fit to the data.

  8. BL LAC candidates for TeV observations

    Energy Technology Data Exchange (ETDEWEB)

    Massaro, F.; Paggi, A.; Errando, M.; D' Abrusco, R.; Masetti, N.; Tosti, G.; Funk, S.

    2013-07-01

    BL Lac objects are the most numerous class of extragalactic TeV-detected sources. One of the biggest difficulties in investigating their TeV emission is due to their limited number, since only 47 BL Lac objects are known to be TeV emitters. In this paper, we propose new criteria to select TeV BL Lac candidates based on infrared and X-ray observations. We apply our selection criteria to the BL Lac objects listed in the ROMA-BZCAT catalog, thereby identifying 41 potential TeV emitters. We then perform a search over a more extended sample combining the ROSAT bright source catalog and the WISE all-sky survey, revealing 54 additional candidates for TeV observations. Our investigation also led to a tentative classification of 16 unidentified X-ray sources as BL Lac candidates. This analysis provides new interesting BL Lac targets for future observations with ground-based Cherenkov telescopes.

  9. Detection of Possible Quasi-periodic Oscillations in the Long-term Optical Light Curve of the BL Lac Object OJ 287

    CERN Document Server

    Bhatta, G; Stawarz, Ł; Ostrowski, M; Winiarski, M; Ogłoza, W; Dróżdz, M; Siwak, M; Liakos, A; Kozieł-Wierzbowska, D; Gazeas, K; Debski, B; Kundera, T; Stachowski, G; Paliya, V S

    2016-01-01

    Detection of periodicity in the broad-band non-thermal emission of blazars has so far been proven to be elusive. However, there are a number of scenarios which could lead to quasi-periodic variations in blazar light curves. For example, orbital or thermal/viscous period of accreting matter around central supermassive black holes could, in principle, be imprinted in the multi-wavelength emission of small-scale blazar jets, carrying as such crucial information about plasma conditions within the jet launching regions. In this paper, we present the results of our time series analysis of $\\sim 9.2$ year-long, and exceptionally well-sampled optical light curve of the BL Lac OJ 287. The study primarily uses the data from our own observations performed at the Mt. Suhora and Krak\\'ow Observatories in Poland, and at the Athens Observatory in Greece. Additionally, SMARTS observations were used to fill in some of the gaps in the data. The Lomb-Scargle Periodogram and the Weighted Wavelet Z-transform methods were employed...

  10. Discovery of VHE γ-rays from the blazar 1ES 1215+303 with the MAGIC telescopes and simultaneous multi-wavelength observations

    Science.gov (United States)

    Aleksić, J.; Alvarez, E. A.; Antonelli, L. A.; Antoranz, P.; Ansoldi, S.; Asensio, M.; Backes, M.; Barres de Almeida, U.; Barrio, J. A.; Bastieri, D.; Becerra González, J.; Bednarek, W.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnoli, G.; Borla Tridon, D.; Bretz, T.; Cañellas, A.; Carmona, E.; Carosi, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Cossio, L.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Cea del Pozo, E.; De Lotto, B.; Delgado Mendez, C.; Diago Ortega, A.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Eisenacher, D.; Elsaesser, D.; Ferenc, D.; Fonseca, M. V.; Font, L.; Fruck, C.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Giavitto, G.; Godinović, N.; González Muñoz, A.; Gozzini, S. R.; Hadasch, D.; Häfner, D.; Herrero, A.; Hildebrand, D.; Hose, J.; Hrupec, D.; Huber, B.; Jankowski, F.; Jogler, T.; Kadenius, V.; Kellermann, H.; Klepser, S.; Krähenbühl, T.; Krause, J.; La Barbera, A.; Lelas, D.; Leonardo, E.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; López, M.; López-Coto, R.; López-Oramas, A.; Lorenz, E.; Makariev, M.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Moldón, J.; Moralejo, A.; Munar-Adrover, P.; Niedzwiecki, A.; Nieto, D.; Nilsson, K.; Nowak, N.; Orito, R.; Paiano, S.; Paneque, D.; Paoletti, R.; Pardo, S.; Paredes, J. M.; Partini, S.; Perez-Torres, M. A.; Persic, M.; Pilia, M.; Pochon, J.; Prada, F.; Prada Moroni, P. G.; Prandini, E.; Puerto Gimenez, I.; Puljak, I.; Reichardt, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Rügamer, S.; Saggion, A.; Saito, K.; Saito, T. Y.; Salvati, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Spanier, F.; Spiro, S.; Stamatescu, V.; Stamerra, A.; Steinke, B.; Storz, J.; Strah, N.; Sun, S.; Surić, T.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Tibolla, O.; Torres, D. F.; Treves, A.; Uellenbeck, M.; Vogler, P.; Wagner, R. M.; Weitzel, Q.; Zabalza, V.; Zandanel, F.; Zanin, R.; Berdyugin, A.; Buson, S.; Järvelä, E.; Larsson, S.; Lähteenmäki, A.; Tammi, J.

    2012-08-01

    Context. We present the discovery of very high energy (VHE, E > 100 GeV) γ-ray emission from the BL Lac object 1ES 1215+303 by the MAGIC telescopes and simultaneous multi-wavelength data in a broad energy range from radio to γ-rays. Aims: We study the VHE γ-ray emission from 1ES 1215+303 and its relation to the emissions in other wavelengths. Methods: Triggered by an optical outburst, MAGIC observed the source in 2011 January - February for 20.3 h. The target was monitored in the optical R-band by the KVA telescope that also performed optical polarization measurements. We triggered target of opportunity observations with the Swift satellite and obtained simultaneous and quasi-simultaneous data from the Fermi Large Area Telescope and from the Metsähovi radio telescope. We also present the analysis of older MAGIC data taken in 2010. Results: The MAGIC observations of 1ES 1215+303 carried out in 2011 January - February resulted in the first detection of the source at VHE with a statistical significance of 9.4σ. Simultaneously, the source was observed in a high optical and X-ray state. In 2010 the source was observed in a lower state in optical, X-ray, and VHE, while the GeV γ-ray flux and the radio flux were comparable in 2010 and 2011. The spectral energy distribution obtained with the 2011 data can be modeled with a simple one zone SSC model, but it requires extreme values for the Doppler factor or the electron energy distribution.

  11. Des Lacs National Wildlife Refuge Water Management Plan 1995

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Des Lacs National Wildlife Refuge Water Management Plan has been developed to meet the station objectives set forth in the Master Plan. The purpose of this plan...

  12. Des Lacs National Wildlife Refuge Water Management Plan 1969

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Des Lacs National Wildlife Refuge Water Management Plan has been developed to meet the station objectives set forth in the Master Plan. The purpose of this plan...

  13. Des Lacs National Wildlife Refuge Water Management Plan 1961

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Des Lacs National Wildlife Refuge Water Management Plan has been developed to meet the station objectives set forth in the Master Plan. The purpose of this plan...

  14. Des Lacs National Wildlife Refuge Water Management Plan 1994

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Des Lacs National Wildlife Refuge Water Management Plan has been developed to meet the station objectives set forth in the Master Plan. The purpose of this plan...

  15. VERITAS Discovery of >200GeV Gamma-ray Emission from the Intermediate-frequency-peaked BL Lac Object W Comae

    CERN Document Server

    Acciari, V A; Beilicke, M; Benbow, W; Bradbury, S M; Buckley, J H; Bugaev, V; Butt, Y; Celik, O; Cesarini, A; Ciupik, L; Chow, Y C K; Cogan, P; Colin, P; Cui, W; Daniel, M K; Ergin, T; Falcone, A D; Fegan, S J; Finley, J P; Finnegan, G; Fortin, P; Fortson, L F; Furniss, A; Gall, D; Gillanders, G H; Grube, J; Guenette, R; Gyuk, G; Hanna, D; Hays, E; Holder, J; Horan, D; Hui, C M; Humensky, T B; Imran, A; Kaaret, Philip; Karlsson, N; Kertzman, M; Kieda, D B; Konopelko, A; Krawczynski, H; Krennrich, F; Lang, M J; Le Bohec, S; Lee, K; Maier, G; McCann, A; McCutcheon, M; Moriarty, P; Mukherjee, R; Nagai, T; Niemiec, J; Ong, R A; Pandel, D; Perkins, J S; Petry, D; Pohl, M; Quinn, J; Ragan, K; Reyes, L C; Reynolds, P T; Roache, E; Rose, H J; Schroedter, M; Sembroski, G H; Smith, A W; Steele, D; Swordy, S P; Toner, J A; Vasilev, V V; Wagner, R; Wakely, S P; Ward, J E; Weekes, T C; Weinstein, A; White, R J; Williams, D A; Wissel, S A; Wood, M; Zitzer, B

    2008-01-01

    We report the detection of very high-energy gamma-ray emission from the intermediate-frequency-peaked BL Lacertae object W Comae (z=0.102) by VERITAS. The source was observed between January and April 2008. A strong outburst of gamma-ray emission was measured in the middle of March, lasting for only four days. The energy spectrum measured during the two highest flare nights is fit by a power-law and is found to be very steep, with a differential photon spectral index of Gamma = 3.81 +- 0.35_stat +- 0.34_syst. The integral photon flux above 200GeV during those two nights corresponds to roughly 9% of the flux from the Crab Nebula. Quasi-simultaneous Swift observations at X-ray energies were triggered by the VERITAS observations. The spectral energy distribution of the flare data can be described by synchrotron-self-Compton (SSC) or external-Compton (EC) leptonic jet models, with the latter offering a more natural set of parameters to fit the data.

  16. Multi-Epoch VLBA Observations of EGRET-Detected Quasars and BL Lac Objects Connection between Superluminal Ejections and Gamma-Ray Flares in Blazars

    CERN Document Server

    Jorstad, S G; Mattox, J R; Aller, M F; Aller, H D; Wehrle, A E; Bloom, S D; Jorstad, Svetlana G; Marscher, Alan P; Mattox, John R; Aller, Margo F; Aller, Hugh D; Wehrle, Ann E; Bloom, Steven D

    2001-01-01

    We examine the coincidence of times of high $\\gamma$-ray flux and ejections of superluminal components from the core in EGRET blazars based on a VLBA monitoring program at 22 and 43 GHz from November 1993 to July 1997. In 23 cases of $\\gamma$-ray flares for which sufficient VLBA data exist, 16 of the flares (in 14 objects) fall within 3$\\sigma$ and 9 of these within 1$\\sigma$ uncertainties of the extrapolated epoch of zero separation from the core of a superluminal radio component. In each of two sources (0528+134 and 1730-130) two successive $\\gamma$-ray flares were followed by the appearance of new superluminal components. We carried out statistical simulations which show that if the number of coincidences $\\ge$ 7 the radio and $\\gamma$-ray events are associated with each other at >99.999% confidence. Our analysis of the observed behavior, including variability of the polarized radio flux, of the sources before, during, and after the $\\gamma$-ray flares suggests that the $\\gamma$-ray events occur in the sup...

  17. The Discovery of Low-Luminosity BL Lacs

    Science.gov (United States)

    Rector, Travis A.; Stocke, John T.

    1995-12-01

    Many of the properties of BL Lacs have become explicable in terms of the ``relativistic beaming'' hypothesis whereby BL Lacs are ``highly beamed'' FR-I radio galaxies (i.e. our line of sight to these objects is nearly along the jet axis). Further, radio-selected BL Lacs (RBLs) are believed to be seen nearly ``on-axis'' (the line-of-sight angle theta ~ 8deg ) while X-ray selected BL Lacs (XBLs) are seen at larger angles (theta ~ 30deg ; the X-ray emitting jet is believed to be less collimated). However, a major problem with this model was that a transition population between beamed BL Lacs and unbeamed FR-Is had not been detected. Low-luminosity BL Lacs may be such a transition population, and were predicted to exist by Browne and Marcha (1993). We present ROSAT HRI images, VLA radio maps and optical spectra which confirm the existence of low-luminosity BL Lacs, objects which were previously mis-identified in the EMSS catalog as clusters of galaxies. Thus our results strengthen the relativistic beaming hypothesis.

  18. Search for TeV $\\gamma$--ray emission from blazar 1ES1218+304 with TACTIC telescope during March-April 2013

    CERN Document Server

    Singh, K K; Tickoo, A K; Rannot, R C; Chandra, P; Agarwal, N K; Gaur, K K; Goyal, A; Goyal, H C; Kumar, N; Marandi, P; Kothari, M; Bhatt, H; Chanchalani, K; Chouhan, N; Dhar, V K; Ghosal, B; Kaul, S R; Koul, M K; Koul, R; Venugopal, K; Bhat, C K; Borwankar, C; Bhagwan, J; Gupta, A C

    2014-01-01

    In this paper, we present results of TeV $\\gamma$--ray observations of the high synchrotron peaked BL Lac object 1ES 1218+304 (z=0.182) with the $TACTIC$ (TeV Atmospheric Cherenkov Telescope with Imaging Camera). The observations are primarily motivated by the unusually hard GeV-TeV spectrum of the source despite its relatively large redshift. The source is observed in the TeV energy range with the $TACTIC$ from March 1, 2013 to April 15, 2013 (MJD 56352--56397) for a total observation time of 39.62 h and no evidence of TeV $\\gamma$--ray activity is found from the source. The corresponding 99$\\%$ confidence level upper limit on the integral flux above a threshold energy of 1.1 TeV is estimated to be 3.41 $\\times10^{-12}$ photons cm$^{-2}$ s$^{-1}$ (i.e $<23\\%$ Crab Nebula flux) assuming a power law differential energy spectrum with photon index 3.0, as previously observed by the $MAGIC$ and $VERITAS$ telescopes. For the study of multi-wavelength emission from the source, we use nearly simultaneous optical,...

  19. Program Evaluation of Community College Learning Assistance Centers: What Do LAC Directors Think?

    Science.gov (United States)

    Franklin, Doug; Blankenberger, Bob

    2016-01-01

    Objective: This study seeks to determine the nature of current program evaluation practices for learning assistance centers (LACs), the practices being used for program evaluation, and whether LAC directors believe their practices are appropriate for evaluating program effectiveness. Method: We conducted a survey (n = 61) of community college LAC…

  20. Flat radio-spectrum galaxies and BL Lacs I. Core properties

    NARCIS (Netherlands)

    Dennett-Thorpe, J; Marcha, MJ

    2000-01-01

    This paper concerns the relationship of BL Lacs and flat-spectrum weak emission-line galaxies. We compare the weak emission-line galaxies and the BL Lacs in a sample of 57 flat-spectrum objects (Marcha et al. 1996), using high-frequency radio and non-thermal optical flux densities, spectral indices

  1. Program Evaluation of Community College Learning Assistance Centers: What Do LAC Directors Think?

    Science.gov (United States)

    Franklin, Doug; Blankenberger, Bob

    2016-01-01

    Objective: This study seeks to determine the nature of current program evaluation practices for learning assistance centers (LACs), the practices being used for program evaluation, and whether LAC directors believe their practices are appropriate for evaluating program effectiveness. Method: We conducted a survey (n = 61) of community college LAC…

  2. Flat radio-spectrum galaxies and BL Lacs I. Core properties

    NARCIS (Netherlands)

    Dennett-Thorpe, J; Marcha, MJ

    This paper concerns the relationship of BL Lacs and flat-spectrum weak emission-line galaxies. We compare the weak emission-line galaxies and the BL Lacs in a sample of 57 flat-spectrum objects (Marcha et al. 1996), using high-frequency radio and non-thermal optical flux densities, spectral indices

  3. Discovery of very high energy gamma rays from 1ES 1440+122

    Science.gov (United States)

    Archambault, S.; Archer, A.; Barnacka, A.; Behera, B.; Beilicke, M.; Benbow, W.; Berger, K.; Bird, R.; Böttcher, M.; Buckley, J. H.; Bugaev, V.; Cardenzana, J. V.; Cerruti, M.; Chen, X.; Christiansen, J. L.; Ciupik, L.; Collins-Hughes, E.; Connolly, M. P.; Cui, W.; Dickinson, H. J.; Dumm, J.; Eisch, J. D.; Errando, M.; Falcone, A.; Federici, S.; Feng, Q.; Finley, J. P.; Fleischhack, H.; Fortson, L.; Furniss, A.; Gillanders, G. H.; Godambe, S.; Griffin, S.; Griffiths, S. T.; Grube, J.; Gyuk, G.; Håkansson, N.; Hanna, D.; Holder, J.; Hughes, G.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kertzman, M.; Khassen, Y.; Kieda, D.; Krawczynski, H.; Kumar, S.; Lang, M. J.; Madhavan, A. S.; Maier, G.; McArthur, S.; McCann, A.; Meagher, K.; Millis, J.; Moriarty, P.; Nelson, T.; Nieto, D.; de Bhróithe, A. O'Faoláin; Ong, R. A.; Otte, A. N.; Park, N.; Perkins, J. S.; Pohl, M.; Popkow, A.; Prokoph, H.; Pueschel, E.; Quinn, J.; Ragan, K.; Rajotte, J.; Reyes, L. C.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Sembroski, G. H.; Shahinyan, K.; Smith, A. W.; Staszak, D.; Sweeney, K.; Telezhinsky, I.; Tucci, J. V.; Tyler, J.; Varlotta, A.; Vassiliev, V. V.; Wakely, S. P.; Welsing, R.; Wilhelm, A.; Williams, D. A.; Zitzer, B.

    2016-09-01

    The BL Lacertae object 1ES 1440+122 was observed in the energy range from 85 GeV to 30 TeV by the VERITAS array of imaging atmospheric Cherenkov telescopes. The observations, taken between 2008 May and 2010 June and totalling 53 h, resulted in the discovery of γ-ray emission from the blazar, which has a redshift z = 0.163. 1ES 1440+122 is detected at a statistical significance of 5.5 standard deviations above the background with an integral flux of (2.8 ± 0.7stat ± 0.8sys) × 10-12 cm-2 s-1 (1.2 per cent of the Crab Nebula's flux) above 200 GeV. The measured spectrum is described well by a power law from 0.2 to 1.3 TeV with a photon index of 3.1 ± 0.4stat ± 0.2sys. Quasi-simultaneous multiwavelength data from the Fermi Large Area Telescope (0.3-300 GeV) and the Swift X-ray Telescope (0.2-10 keV) are additionally used to model the properties of the emission region. A synchrotron self-Compton model produces a good representation of the multiwavelength data. Adding an external-Compton or a hadronic component also adequately describes the data.

  4. Discovery of Very High Energy Gamma Rays from 1ES 1440+122

    CERN Document Server

    Archambault, S; Barnacka, A; Behera, B; Beilicke, M; Benbow, W; Berger, K; Bird, R; Boettcher, M; Buckley, J H; Bugaev, V; Cardenzana, J V; Cerruti, M; Chen, X; Christiansen, J L; Ciupik, L; Collins-Hughes, E; Connolly, M P; Cui, W; Dickinson, H J; Dumm, J; Eisch, J D; Errando, M; Falcone, A; Federici, S; Feng, Q; Finley, J P; Fleischhack, H; Fortson, L; Furniss, A; Gillanders, G H; Godambe, S; Griffin, S; Griffiths, S T; Grube, J; Gyuk, G; Haakansson, N; Hanna, D; Holder, J; Hughes, G; Johnson, C A; Kaaret, P; Kar, P; Kertzman, M; Khassen, Y; Kieda, D; Krawczynski, H; Kumar, S; Lang, M J; Madhavan, A S; Maier, G; McArthur, S; McCann, A; Meagher, K; Millis, J; Moriarty, P; Nelson, T; Nieto, D; de Bhroithe, A O'Faolain; Ong, R A; Otte, A N; Park, N; Perkins, J S; Pohl, M; Popkow, A; Prokoph, H; Pueschel, E; Quinn, J; Ragan, K; Rajotte, J; Reyes, L C; Reynolds, P T; Richards, G T; Roache, E; Sembroski, G H; Shahinyan, K; Smith, A W; Staszak, D; Sweeney, K; Telezhinsky, I; Tucci, J V; Tyler, J; Varlotta, A; Vassiliev, V V; Wakely, S P; Welsing, R; Wilhelm, A; Williams, D A; Zitzer, B

    2016-01-01

    The BL Lacertae object 1ES 1440+122 was observed in the energy range from 85 GeV to 30 TeV by the VERITAS array of imaging atmospheric Cherenkov telescopes. The observations, taken between 2008 May and 2010 June and totalling 53 hours, resulted in the discovery of $\\gamma$-ray emission from the blazar, which has a redshift $z$=0.163. 1ES 1440+122 is detected at a statistical significance of 5.5 standard deviations above the background with an integral flux of (2.8$\\pm0.7_{\\mathrm{stat}}\\pm0.8_{\\mathrm{sys}}$) $\\times$ 10$^{-12}$ cm$^{-2}$ s$^{-1}$ (1.2\\% of the Crab Nebula's flux) above 200 GeV. The measured spectrum is described well by a power law from 0.2 TeV to 1.3 TeV with a photon index of 3.1 $\\pm$ 0.4$_{\\mathrm{stat}}$ $\\pm$ 0.2$_{\\mathrm{sys}}$. Quasi-simultaneous multi-wavelength data from the Fermi Large Area Telescope (0.3--300 GeV) and the Swift X-ray Telescope (0.2--10 keV) are additionally used to model the properties of the emission region. A synchrotron self-Compton model produces a good repr...

  5. The REX survey as a Tool to Test the Beaming Model for BL Lacs

    Science.gov (United States)

    Caccianiga, A.; della Ceca, R.; Gioia, I. M.; Maccacaro, T.; Wolter, A.

    We present the preliminary properties of the BL Lacs discovered in the REX survey (Caccianiga et al. 1998). In particular, we discuss a few sources with optical spectral properties ``intermediate'' between those of BL Lacs and those of elliptical galaxies. These objects could harbour weak (in the optical band) sources of non-thermal continuum in their nuclei and, if confirmed, they could represent the faint tail of the BL Lac population. The existence of such ``weak'' BL Lacs is matter of discussion in recent literature (e.g. Marcha et al. 1996) and could lead to a revision of the defining criteria of a BL Lac and, consequently, of their cosmological and statistical properties.

  6. Increasing X-Ray Brightness of HBL Source 1ES 1727+650

    Science.gov (United States)

    Kapanadze, Bidzina

    2017-02-01

    The nearby TeV-detected HBL object 1ES 1727+502 (1Zw 187, z=0.055) has been targeted 111 times by X-ray Telescope (XRT) onboard Swift since 2010 April 2. During this monitoring, the 0.3-10 keV count rate varied by a factor of 17.4 (see http://www.swift.psu.edu/monitoring/source.php?source=QSOB1727+502) and showed a prolonged X-ray flaring activity during 2015 March - 2016 February, revealed mainly via the Target of Opportunity observations performed in the framework of our request of different urgencies (Request Number 6571, 6606, 6717, 6809, 6927, 7322, 7355, 7379, 7390, 7404, 7430, 7441, 7516, 7565; see Kapanadze et al. 2015, Atel #8224, #7342).

  7. MAGIC observations of the February 2014 flare of 1ES 1011+496 and ensuing constraint of the EBL density

    CERN Document Server

    Ahnen, M L; Antonelli, L A; Antoranz, P; Babic, A; Banerjee, B; Bangale, P; de Almeida, U Barres; Barrio, J A; González, J Becerra; Bednarek, W; Bernardini, E; Biasuzzi, B; Bil, A; Blanch, O; Bonnefoy, S; Bonnoli, G; Borracci, F; Bretz, T; Carmona, E; Carosi, A; Chatterjee, A; Clavero, R; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Lotto, B; Wilhelmi, E de O na; Mendez, C Delgado; Di Pierro, F; Prester, D Dominis; Dorner, D; Doro, M; Einecke, S; Glawion, D Eisenacher; Elsaesser, D; Fernández-Barral, A; Fidalgo, D; Fonseca, M V; Font, L; Frantzen, K; Fruck, C; Galindo, D; López, R J García; Garczarczyk, M; Terrats, D Garrido; Gaug, M; Giammaria, P; Godinovic, N; Muñoz, A González; Guberman, D; Hahn, A; Hanabata, Y; Hayashida, M; Herrera, J; Hose, J; Hrupec, D; Hughes, G; Idec, W; Kodani, K; Konno, Y; Kubo, H; Kushida, J; La Barbera, A; Lelas, D; Lindfors, E; Lombardi, S; Longo, F; López, M; López-Coto, R; López-Oramas, A; Lorenz, E; Majumdar, P; Makariev, M; Mallot, K; Maneva, G; Manganaro, M; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martínez, M; Mazin, D; Menzel, U; Mira, J M; Mirzoyan, R; Moralejo, A; Moretti, E; Nakajima, D; Neustroev, V; Niedzwiecki, A; Rosillo, M Nievas; Nilsson, K; Nishijima, K; Noda, K; Orito, R; Overkemping, A; Paiano, S; Palacio, J; Palatiello, M; Paneque, D; Paoletti, R; Paredes, J M; Paredes-Fortuny, X; Persic, M; Poutanen, J; Moroni, P G Prada; Prini, E; Puljak, I; Rhode, W; Ribó, M; Rico, J; Garcia, J Rodriguez; Saito, T; Satalecka, K; Schultz, C; Schweizer, T; Shore, S N; Sillanpaa, A; Sitarek, J; Snidaric, I; Sobczynska, D; Stamerra, A; Steinbring, T; Strzys, M; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzic, T; Tescaro, D; Teshima, M; Thaele, J; Torres, D F; Toyama, T; Treves, A; Verguilov, V; Vovk, I; Ward, J E; Will, M; Wu, M H; Zanin, R

    2016-01-01

    In February-March 2014, the MAGIC telescopes observed the high-frequency peaked BL Lac 1ES 1011+496 (z=0.212) in flaring state at very-high energy (VHE, E>100GeV). The flux reached a level more than 10 times higher than any previously recorded flaring state of the source. We present the description of the characteristics of the flare presenting the light curve and the spectral parameters of the night-wise spectra and the average spectrum of the whole period. From these data we aim at detecting the imprint of the Extragalactic Background Light (EBL) in the VHE spectrum of the source, in order to constrain its intensity in the optical band. For this we implement the method developed by the H.E.S.S. collaboration in which the intrinsic energy spectrum of the source is modeled with a simple function, and the EBL-induced optical depth is calculated using a template EBL model. The likelihood of the observed spectrum is then maximized, including a normalization factor for the EBL opacity among the free parameters. F...

  8. A Hard X-Ray View of Two Distant VHE Blazars: 1ES 1101-232 and 1ES 1553+113

    CERN Document Server

    Reimer, A; Madejski, G; Reimer, O; Dorner, D

    2008-01-01

    TeV blazars are known as prominent nonthermal emitters across the entire electromagnetic spectrum with their photon power peaking in the X-ray and TeV bands. If distant, absorption of gamma-ray photons by the extragalactic background light (EBL) alters the intrinsic TeV spectral shape, thereby affecting the overall interpretation. Suzaku observations for two of the more distant TeV blazars known to date, 1ES 1101-232 and 1ES 1553+113, were carried out in 2006 May and July, respectively, including a quasi-simultaneous coverage with the state-of-the-art Cerenkov telescope facilities. We report on the resulting data sets with emphasis on the X-ray band and set in context to their historical behavior. During our campaign, we did not detect any significant X-ray or gamma-ray variability. 1ES 1101-232 was found in a quiescent state with the lowest X-ray flux ever measured. The combined XIS and HXD PIN data for 1ES 1101-232 and 1ES 1553+113 clearly indicate spectral curvature up to the highest hard X-ray data point ...

  9. A Hard X-Ray View of Two Distant VHE Blazars: 1ES 1101-232 and 1ES 1553+113

    Science.gov (United States)

    Reimer, A.; Costamante, L.; Madejski, G.; Reimer, O.; Dorner, D.

    2008-08-01

    TeV blazars are known as prominent nonthermal emitters across the entire electromagnetic spectrum with their photon power peaking in the X-ray and TeV bands. If distant, absorption of γ-ray photons by the extragalactic background light (EBL) alters the intrinsic TeV spectral shape, thereby affecting the overall interpretation. Suzaku observations for two of the more distant TeV blazars known to date, 1ES 1101-232 and 1ES 1553+113, were carried out in 2006 May and July, respectively, including a quasi-simultaneous coverage with the state-of-the-art Cerenkov telescope facilities. We report on the resulting data sets with emphasis on the X-ray band and set in context to their historical behavior. During our campaign, we did not detect any significant X-ray or γ-ray variability. 1ES 1101-232 was found in a quiescent state with the lowest X-ray flux ever measured. The combined XIS and HXD PIN data for 1ES 1101-232 and 1ES 1553+113 clearly indicate spectral curvature up to the highest hard X-ray data point (~30 keV), manifesting as softening with increasing energy. We describe this spectral shape by either a broken power law or a log-parabolic fit with equal statistical goodness of fits. The combined 1ES 1553+113 very high energy spectrum (90-500 GeV) did not show any significant changes with respect to earlier observations. The resulting contemporaneous broadband spectral energy distributions of both TeV blazars are discussed in view of implications for intrinsic blazar parameter values, taking into account the γ-ray absorption in the EBL.

  10. A Hard X-ray View on Two Distant VHE Blazars: 1ES 1101-232 and 1ES 1553+113

    Energy Technology Data Exchange (ETDEWEB)

    Reimer, A.; Costamente, L.; /Stanford U., HEPL /KIPAC, Menlo Park; Madejski, G.; /KIPAC, Menlo Park /SLAC; Reimer, O.; /Stanford U., HEPL /KIPAC, Menlo Park; Dorner, D.; /Wurzburg U.

    2008-05-02

    TeV-blazars are known as prominent non-thermal emitters across the entire electromagnetic spectrum with their photon power peaking in the X-ray and TeV-band. If distant, absorption of -ray photons by the extragalactic background light (EBL) alters the intrinsic TeV spectral shape, thereby affecting the overall interpretation. Suzaku observations for two of the more distant TeV-blazars known to date, 1ES 1101-232 and 1ES 1553+113, were carried out in May and July 2006, respectively, including a quasi-simultaneous coverage with the state of the art Cherenkov telescope facilities. We report on the resulting data sets with emphasis on the X-ray band, and set into context to their historical behavior. During our campaign, we did not detect any significant X-ray or {gamma}-ray variability. 1ES 1101-232 was found in a quiescent state with the lowest X-ray flux ever measured. The combined XIS and HXD PIN data for 1ES 1101-232 and 1ES 1553+113 clearly indicate spectral curvature up to the highest hard X-ray data point ({approx} 30 keV), manifesting as softening with increasing energy. We describe this spectral shape by either a broken power law or a log-parabolic fit with equal statistical goodness of fits. The combined 1ES 1553+113 very high energy spectrum (90-500 GeV) did not show any significant changes with respect to earlier observations. The resulting contemporaneous broadband spectral energy distributions of both TeV-blazars are discussed in view of implications for intrinsic blazar parameter values, taking into account the {gamma}-ray absorption in the EBL.

  11. Monitoring of the Tev Blazar 1ES 1101-232 with RXTE and H.E.S.S.

    Science.gov (United States)

    Puehlhofer, Gerd

    We want to carry out an observation campaign of 10 nights with HESS and RXTE on 1ES 1101-232, the by far most distant object detected in TeV gamma-rays. HESS is a second generation TeV Cherenkov telescope system with a much better sensitivity and lower energy threshold compared to previous instruments. The campaign will be accompanied by observations of various other instruments. Our goals are (a) to measure and understand the temporal evolution of the broad-band spectral energy distribution of Blazars, in order to allow more detailed modeling of radiation processes and particle acceleration in Blazar jets, and (b) to investigate the cosmic Extragalactic Background Light by studying the absorption of TeV gamma-rays, for which 1ES 1101-232 (z=0.186) is an extremely important target.

  12. Present research on the composition and application of lac

    Institute of Scientific and Technical Information of China (English)

    Wang Xia; Li Jian-zhang; Fan Yong-ming; Jin Xiao-juan

    2006-01-01

    Lac is a natural polymer with atoxigenic, renewable, and naturally degradable characteristics. Nowadays, more and more attentions are paid to environment protection and resource conservation, so it has great significance to study the composition and application of lac. The paper summarizes the research of lac composition and emphasizes on the present research of lac resin. The applications of lac are also introduced. In addition, some suggestions are proposed, which is expected to provide some scientific references for further studies of lac.

  13. New results from the HRX BL Lac sample

    CERN Document Server

    Beckmann, V; Beckmann, Volker; Wolter, Anna

    2000-01-01

    We present results for the Hamburg BL Lac sample, based on data provided by the RASS-BSC. By fitting a single power law to the X-ray data we find, in a number of objects, an additional absorbing component to the galactic value of NH, which might be attributed to intrinsic absorption. A more probable cause seems however to be a curvature in the X-ray spectra in the sense that they are more curved for steeper slopes. The known relation between the X-ray spectral slope and the ratio between optical and X-ray flux alpha_ox also applies to this BL Lac sample, even though less significant than in previous works. We also find a dependence of X-ray luminosity on alpha_ox.

  14. CCC/WPA study : Des Lacs NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Summary of the Civilian Conservation Corps (CCC) camp at Des Lacs National Wildlife Refuge from July 1935-May 1942 to carry on restoration and development of Des...

  15. Wood duck studies : Des Lacs NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This memorandum summarizes wood duck studies on Des Lacs National Wildlife Refuge and provides a brief history on the status of wood ducks on the edge of their...

  16. The Coronae of AR Lac

    CERN Document Server

    Huenemoerder, D P; Drake, J J; Sanz-Forcada, J; Canizares, Claude R.; Drake, Jeremy J.; Huenemoerder, David P.; Sanz-Forcada, Jorge

    2003-01-01

    We observed the coronally active eclipsing binary, AR Lac, with the High Energy Transmission Grating on Chandra for a total of 97 ks, spaced over five orbits, at quadratures and conjunctions. Contemporaneous and simultaneous EUV spectra and photometry were also obtained with the Extreme Ultraviolet Explorer. Significant variability in both X-ray and EUV fluxes were observed, dominated by at least one X-ray flare and one EUV flare. We saw no evidence of primary or secondary eclipses. X-ray flux modulation was largest at high temperature, indicative of flare heating of coronal plasma. Line widths interpreted in terms of Doppler broadening suggest that both binary stellar components are active. From line fluxes obtained from total integrated spectra, we have modeled the emission measure and abundance distributions. A strong maximum was found in the differential emission measure, characterized by peaks at log T = 6.9 and 7.4, together with a weak but significant cooler maximum near log T=6.2, and a moderately str...

  17. On the magnetization of BL Lac jets

    CERN Document Server

    Tavecchio, F

    2015-01-01

    The current paradigm foresees that relativistic jets are launched as magnetically dominated flows, whose magnetic power is progressively converted to kinetic power of of the matter of the jet, until equipartition is reached. Therefore, at the end of the acceleration phase, the jet should still carry a substantial fraction ($\\approx$ half) of its power in the form of a Poynting flux. It has been also argued that, in these conditions, the best candidate particle acceleration mechanism is efficient reconnection of magnetic field lines, for which it is predicted that magnetic field and accelerated relativistic electron energy densities are in equipartition.Through the modeling of the jet non--thermal emission, we explore if equipartition is indeed possible in BL Lac objects, i.e. low-power blazars with weak or absent broad emission lines. We find that one-zone models (for which only one region is involved in the production of the radiation we observe) the particle energy density is largely dominating (by 1-2 orde...

  18. The CLASS BL Lac sample: The Radio Luminosity Function

    CERN Document Server

    Marcha, M J M

    2013-01-01

    This paper presents a new sample of BL Lac objects selected from a deep (30 mJy) radio survey of flat spectrum radio sources (the CLASS blazar survey, henceforth CBS). The sample is one of the largest well defined samples in the low power regime with a total of 130 sources of which 55 satisfy the 'classical' optical BL Lac selection criteria, and the rest have indistinguishable radio properties. The primary goal of this study is to establish the Radio Luminosity Function (RLF) on firm statistical ground at low radio luminosities where previous samples have not been able to investigate. The gain of taking a peek at lower powers is the possibility to search for the flattening of the LF which is a feature predicted by the beaming model but which has remained elusive to observational confirmation. In this study we extend for the first time the BL Lac RLF down to very low radio powers ~10^22 W/Hz, ie, two orders of magnitude below the RLF currently available in the literature. In the process we confirm the importa...

  19. ELECTROPORATION OF CONFLUENT HM-1 ES CELLS LEADS TO HIGHER AMOUNT COLONIES

    Directory of Open Access Journals (Sweden)

    A.ALENA BENCSIK

    2013-12-01

    Full Text Available Electroporation is used to induce homologous recombination in the genome of the murine ES (embryonic stem cells. Routinelly subconfluent ES cells are recommended to be used in such experiments. Electroporation of immunoglobulin specific targeting vectors with different length of homology leads to reduced number of selected colonies. The enrichment of double selected colonies is high and thus the amount of HM-1 ES cell colonies for the analysis is very low. Here we show that the electroporation of confluent HM-1 ES cells leads to an increased amount of simple and double selected colonies.

  20. The drift plain of Des Lacs National Wildlife Refuge, North Dakota : Small mammals and their grassland habitat

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes a study of small mammals and their habitats at Des Lacs National Wildlife Refuge, completed by a University of Wisconsin intern. Objectives of...

  1. The Radio-optical Spectra of BL Lacs and Possible Relatives

    Science.gov (United States)

    Dennett-Thorpe, J.

    I consider the suggestion that, in a complete sample of flat-spectrum radio sources with available optical spectra (Marcha et al 1996), the strong emission line objects, or those with passive elliptical spectra are close relatives of the BL Lacs. New observations at four frequencies from 8 to 43GHz are presented, together with evidence for radio variability. Combined with other radio and optical data from the literature, we are able to construct the non-thermal SEDs and use these to address the questions: are the optically passive objects potentially `unrecognised' BL Lacs (either intrinsically weak and/or hidden by starlight)? What is the relationship between the surprising number of strong emission-line objects and the BL Lacs?

  2. The comparison between LAC and ALA

    Directory of Open Access Journals (Sweden)

    Tzu-heng Chiu

    2000-12-01

    Full Text Available A good library association serves its members, improves the librarianship, and helps library institutions achieving their missions. This article describes the history, missions and goals, organization structure, membership, financial sources, professional activities, publication, and website of the Library Association of China (LAC and American Library Association (ALA, respectively. Considering social / cultural / political differences between Taiwan and the United Sates, the author then compares these two library associations from the eight factors mentioned above. At the end, suggestions for the LAC are proposed.[Article content in Chinese

  3. MAGIC observations of the February 2014 flare of 1ES 1011+496 and ensuing constraint of the EBL density

    Science.gov (United States)

    Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; Banerjee, B.; Bangale, P.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Biasuzzi, B.; Biland, A.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carmona, E.; Carosi, A.; Chatterjee, A.; Clavero, R.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; de Oña Wilhelmi, E.; Delgado Mendez, C.; Di Pierro, F.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher Glawion, D.; Elsaesser, D.; Fernández-Barral, A.; Fidalgo, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Giammaria, P.; Godinović, N.; González Muñoz, A.; Guberman, D.; Hahn, A.; Hanabata, Y.; Hayashida, M.; Herrera, J.; Hose, J.; Hrupec, D.; Hughes, G.; Idec, W.; Kodani, K.; Konno, Y.; Kubo, H.; Kushida, J.; La Barbera, A.; Lelas, D.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Coto, R.; López-Oramas, A.; Lorenz, E.; Majumdar, P.; Makariev, M.; Mallot, K.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Moretti, E.; Nakajima, D.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nilsson, K.; Nishijima, K.; Noda, K.; Orito, R.; Overkemping, A.; Paiano, S.; Palacio, J.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Persic, M.; Poutanen, J.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Rhode, W.; Ribó, M.; Rico, J.; Rodriguez Garcia, J.; Saito, T.; Satalecka, K.; Schultz, C.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Stamerra, A.; Steinbring, T.; Strzys, M.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Torres, D. F.; Toyama, T.; Treves, A.; Verguilov, V.; Vovk, I.; Ward, J. E.; Will, M.; Wu, M. H.; Zanin, R.

    2016-05-01

    Context. During February-March 2014, the MAGIC telescopes observed the high-frequency peaked BL Lac 1ES 1011+496 (z = 0.212) in flaring state at very-high energy (VHE, E> 100 GeV). The flux reached a level of more than ten times higher than any previously recorded flaring state of the source. Aims: To describe the characteristics of the flare presenting the light curve and the spectral parameters of the night-wise spectra and the average spectrum of the whole period. From these data we aim to detect the imprint of the extragalactic background light (EBL) in the VHE spectrum of the source, to constrain its intensity in the optical band. Methods: We analyzed the gamma-ray data from the MAGIC telescopes using the standard MAGIC software for the production of the light curve and the spectra. To constrain the EBL, we implement the method developed by the H.E.S.S. collaboration, in which the intrinsic energy spectrum of the source is modeled with a simple function (≤4 parameters), and the EBL-induced optical depth is calculated using a template EBL model. The likelihood of the observed spectrum is then maximized, including a normalization factor for the EBL opacity among the free parameters. Results: The collected data allowed us to describe the night-wise flux changes and also to produce differential energy spectra for all nights in the observed period. The estimated intrinsic spectra of all the nights could be fitted by power-law functions. Evaluating the changes in the fit parameters, we conclude that the spectral shape for most of the nights were compatible, regardless of the flux level, which enabled us to produce an average spectrum from which the EBL imprint could be constrained. The likelihood ratio test shows that the model with an EBL density 1.07 (-0.20, +0.24)stat+sys, relative to the one in the tested EBL template, is preferred at the 4.6σ level to the no-EBL hypothesis, with the assumption that the intrinsic source spectrum can be modeled as a log

  4. Refuge development report : Des Lacs Migratory Waterfowl Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Report on the development of Des Lacs National Wildlife Refuge. This report introduces the physical and biological characteristics of the Des Lacs area. This report...

  5. [Des Lacs National Wildlife Refuge habitat improvement to combat botulism

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This documents discusses the possibilities of ditching the Upper Des Lacs lake as a means of combating botulism on the Des Lacs National Wildlife Refuge.

  6. CLUSTERING OF γ-RAY-SELECTED 2LAC FERMI BLAZARS

    Energy Technology Data Exchange (ETDEWEB)

    Allevato, V.; Finoguenov, A. [Department of Physics, University of Helsinki, Gustaf Hällströmin katu 2a, FI-00014 Helsinki (Finland); Cappelluti, N. [University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States)

    2014-12-20

    We present the first measurement of the projected correlation function of 485 γ-ray-selected blazars, divided into 175 BL Lacertae (BL Lacs) and 310 flat-spectrum radio quasars (FSRQs) detected in the 2 year all-sky survey by the Fermi-Large Area Telescope. We find that Fermi BL Lacs and FSRQs reside in massive dark matter halos (DMHs) with log M{sub h} = 13.35{sub −0.14}{sup +0.20} and log M{sub h} = 13.40{sub −0.19}{sup +0.15} h {sup –1} M {sub ☉}, respectively, at low (z ∼ 0.4) and high (z ∼ 1.2) redshift. In terms of clustering properties, these results suggest that BL Lacs and FSRQs are similar objects residing in the same dense environment typical of galaxy groups, despite their different spectral energy distributions, power, and accretion rates. We find no difference in the typical bias and hosting halo mass between Fermi blazars and radio-loud active galactic nuclei (AGNs), supporting the unification scheme simply equating radio-loud objects with misaligned blazar counterparts. This similarity in terms of the typical environment they preferentially live in, suggests that blazars tend to occupy the center of DMHs, as already pointed out for radio-loud AGNs. This implies, in light of several projects looking for the γ-ray emission from DM annihilation in galaxy clusters, a strong contamination from blazars to the expected signal from DM annihilation.

  7. The lac Operon: Fluctuations, Growth and Evolution

    NARCIS (Netherlands)

    Kiviet, D.J.

    2010-01-01

    This thesis is concerned with two distinct fundamental research questions that are both investigated using the E. coli lac system. In the first chapters we investigate what the shape of biological fitness landscapes look like. Chapter 2 reviews recent progress in measurement of empirical fitness lan

  8. A Search for Low-Luminosity BL Lacertae Objects

    Science.gov (United States)

    Rector, Travis A.; Stocke, John T.; Perlman, Eric S.

    1999-05-01

    Many properties of BL Lacs have become explicable in terms of the ``relativistic beaming'' hypothesis, whereby BL Lacs are FR 1 radio galaxies viewed nearly along the jet axis. However, a possible problem with this model is that a transition population between beamed BL Lacs and unbeamed FR 1 galaxies has not been detected. A transition population of ``low-luminosity BL Lacs'' was predicted to exist in abundance in X-ray-selected samples such as the Einstein Extended Medium Sensitivity Survey (EMSS) by Browne & Marcha. However, these BL Lacs may have been misidentified as clusters of galaxies. We have conducted a search for such objects in the EMSS with the ROSAT High-Resolution Imager (HRI) here we present ROSAT HRI images, optical spectra, and VLA radio maps for a small number of BL Lacs that were previously misidentified in the EMSS catalog as clusters of galaxies. While these objects are slightly lower in luminosity than other EMSS BL Lacs, their properties are too similar to the other BL Lacs in the EMSS sample to ``bridge the gap'' between BL Lacs and FR 1 radio galaxies. Also, the number of new BL Lacs found is too low to alter significantly the X-ray luminosity function or value for the X-ray-selected EMSS BL Lac sample. Thus, these observations do not explain fully the discrepancy between the X-ray- and radio-selected BL Lac samples.

  9. Infrared Polarization and Beaming Effect for BL Lac Objects

    Institute of Scientific and Technical Information of China (English)

    MEI Dong-Cheng; XIE Guang-Zhong

    2001-01-01

    With the idea of the beaming models, we derive a relation between the observed polarization and Dopplercorrected magnitude; that is, the observed polarization is in anti-correlation with the Doppler-corrected magnitude. Making use of the infrared data observed simultaneously by Impey et al. [Mon. Not. R. Astron. Soc.200 (1982) 19; 209 (1984) 245] and Holmes et al. [ibid. 210 (1984) 961] we found that: (1) there is a significant correlation between the observed maximum polarization and Doppler-corrected magnitude but the polarization is not in anti-correlation with the Doppler-corrected magnitude; (2) the maximum infrared polarization is strongly correlated with the maximum optical polarization. Our conclusion is that the infrared polarization depends only on the degree of ordering of the magnetic field in the synchrotron emission regions and not on the beaming effect.Both infrared and optical emissions originate from the synchrotron radiation.

  10. Structure and dynamics in Lac repressor-DNA interactions

    NARCIS (Netherlands)

    Kaptein, R.

    2013-01-01

    The E. coli lac operon is the classical model for gene regulation in bacteria. An overview will be given of our work on the lac repressor-operator system. An early result was the 3D structure of lac headpiece in 1985, one of the first protein structures determined by NMR. Our studies of the structur

  11. NMR studies of the allosteric effectors of the lac operon

    NARCIS (Netherlands)

    Romanuka, J.

    2009-01-01

    The aim of this thesis is to characterize the regulatory mechanism of the Lac repressor which is the molecular switch of the lac operon. Lac repressor binds to its cognate DNA operator and inhibits transcription. When an inducer binds to the protein, it triggers a conformational change that releases

  12. Lac Courte Oreilles Energy Analysis Project

    Energy Technology Data Exchange (ETDEWEB)

    Leslie Isham; Denise Johnson

    2009-04-01

    The Lac Courte Oreilles Tribe applied for first step funding in 2007 and was awarded in October of that year. We wanted to perform an audit to begin fulfilling two commitments we made to our membership and resolutions that we adopted. One was the Kyoto Protocol and reduce our carbon emissions by 25% and to produce 25% of our energy by sustainable means. To complete these goals we needed to begin with first assessing what our carbon emissions are and begin taking the steps to conserve on the energy we currently use. The First Step Grant gave us the opportunity to do this. Upon funding the Energy Project was formed under the umbrella of the LCO Public Works Department and Denise Johnson was hired as the coordinator. She quickly began fulfilling the objectives of the project. Denise began by contact the LCO College and hiring interns who were able to go to each Tribal entity and perform line logging to read and document the energy used for each electrical appliance. Data was also gathered for one full year from each entity for all their utility bills (gasoline, electric, natural gas, fuel oil, etc.). Relationships were formed with the Green Team and other Green Committees in the area that could assist us in this undertaking. The Energy Task Force was of great assistance as well recommending other committees and guidance to completing our project. The data was gathered, compiled and placed into spreadsheets that would be understandable for anyone who didn't have a background in Renewable Resources. While gathering the data Denise was also looking for ways to conserve energy usage, policies changes to implement and any possible viable renewable energy resources. Changes in the social behaviors of our members and employees will require further education by workshops, energy fairs, etc.. This will be looked into and done in coordination with our schools. The renewable resources seem most feasible are wind resources as well as Bio Mass both of which need further

  13. Another Very Strong X-ray Flare in 1ES 1959+650

    Science.gov (United States)

    Kapanadze, Bidzina

    2016-10-01

    The nearby TeV-detected HBL source 1ES 1959+650 (z=0.047) has been observed five times by X-ray Telescope onboard the Swift satellite (Swift-XRT) in the framework of our Target of Opportunity (ToO) requests of different urgencies (ToO Request Number: 8544, 8614, 8623; see https://www.swift.psu.edu/secure/toop/summary.php) which revealed an onset of the third very strong X-ray flare during the last 1 year period.

  14. -Ray Emission from the Extreme Blazar 1ES 0229+200

    Indian Academy of Sciences (India)

    J. Li; T. Kang; Y. G. Zheng

    2014-09-01

    Based on the traditional Synchrotron Self-Compton (SSC) model, we consider a secondary γ -ray emission component to an extreme blazar 1ES 0229 + 200 for the multiwavelength radiation. By assuming a suitable electron spectra and Inter-Galactic Magnetic Field (IGMF), we obtained excellent fits to observed spectra of the source. This indicated that the observed excess GeV -rays emission can be explained by secondary -rays produced through inverse Compton scattering of ± pairs against Cosmic Microwave Background (CMB) photons.

  15. The hadronic origin of hard gamma-ray spectrum from blazar 1ES 1101-232

    CERN Document Server

    Cao, Gang

    2014-01-01

    The very hard $\\gamma$-ray spectrum from distant blazars challenges the traditional synchrotron self-Compton (SSC) model, which may indicate that there is the contribution of an additional high-energy component beyond the SSC emission. In this paper, we study the possible origin of the hard $\\gamma$-ray spectrum from distant blazars. We develop a model to explain the hard $\\gamma$-ray spectrum from blazar 1ES 1101-232. In the model, the optical and X-ray radiation would come from the synchrotron radiation of primary electrons and secondary pairs, the GeV emission would be produced by the SSC process, however, the hard $\\gamma$-ray spectrum would originate from the decay of neutral pion produced through proton-photon interactions with the synchrotron radiation photons within the jet. Our model can explain the observed SED of 1ES 1101-232 well, especially the very hard $\\gamma$-ray spectrum. However, our model requires the very large proton power to efficiently produce the $\\gamma$-ray through proton-photon int...

  16. Variability of the Blazar BL Lac in 2001

    Science.gov (United States)

    Barnaby, D.; Carini, M.; Wills, W.; Atkerson, A.; Monroe, T.; Ryle, W.

    2002-06-01

    BL Lacertae (z=0.0686) is the archetype of a class of active galactic nuclei known as BL Lacertae objects. BL Lacertae objects are a branch of the class of objects known as blazars, and BL Lac is one of the best-observed blazars. It exhibits large amplitude (> 1 mag) variability at optical wavelengths over years, months, and weeks. In the last few years, BL Lac has returned to a highly active state, and a concerted effort is being made to discern the mechanism(s) responsible for this high-degree of variability. To do this many observatories have begun to monitor BL Lacertae regularly in an attempt to measure the light curve 24-hours per day in a collaboration called the Whole Earth Blazar Telescope (WEBT). To date the WEBT results show an approximately 7-hour time scale for short outbursts and suggest a measurable distinction between spectral changes during low-brightness and out-burst phases. Western Kentucky University's Bell Astrophysical Observatory began regularly monitoring BL Lacertae in the latter half of 2001 with our newly refurbished 0.6meter telescope. We present an R-band light curve derived from photometric CCD observations covering the monitoring period. Generally, the light curve ranges between R=13.6-14.4, which is similar to the range measured by WEBT observers during the low-brightness phase in 2000. In addition to the long-term light curve, we present R-band microvariability light curves derived from persistent monitoring over 2 different nights during the same period. These show monotonic changes in R-band brightness of up 0.25 magnitudes over 3 hours. We gratefully acknowledge NASA for funding this research through grant NAG5-8762, and Western Kentucky University for funds provided through the Applied Research and Technology Program of Distinction.

  17. A recent strong X-ray flaring activity of 1ES 1959+650 with possibly less efficient stochastic acceleration

    Science.gov (United States)

    Kapanadze, B.; Dorner, D.; Vercellone, S.; Romano, P.; Kapanadze, S.; Mdzinarishvili, T.

    2016-09-01

    We present an X-ray flaring activity of 1ES 1959+650 in 2015 August-2016 January, which was the most powerful and prolonged during the 10.75 yr period since the start of its monitoring with X-ray Telescope onboard Swift. A new highest historical 0.3-10 keV count rate was recorded three times that makes this object the third BL Lacertae source exceeding the level of 20 counts s-1. Along with the overall variability by a factor of 5.7, this epoch was characterized by fast X-ray flares by a factor of 2.0-3.1, accompanied with an extreme spectral variability. The source also shows a simultaneous flaring activity in the optical - UV and 0.3-100 GeV bands, although a fast γ-ray flare without significant optical - X-ray counterparts is also found. In contrast to the X-ray flares in the previous years, the stochastic acceleration seems be less important for the electrons responsible for producing X-ray emission during this flare that challenges the earlier suggestion that the electrons in the jets of TeV-detected BL Lacertae objects should undergo an efficient stochastic acceleration resulting in a lower X-ray spectral curvature.

  18. Relationship between lupus anticoagulant (LAC) and pregnancy-induced hypertension.

    Science.gov (United States)

    Matsumoto, T; Sagawa, N; Ihara, Y; Kobayashi, F; Itoh, H; Mori, T

    1995-01-01

    Lupus anticoagulant (LAC), a serum antiphospholipid autoantibody, is believed to be one of the causes of infertility or fetal loss. The purpose of the present study was to evaluate the role of LAC in the pathogenesis of hypertension during pregnancy. In this study, 20 pregnant women with hypertension were classified into two groups: 14 patients who did not have hypertension before the pregnancy but developed it during the pregnancy (pregnancy-induced hypertension; Group A) and 6 patients who had hypertensive or renal disease before the pregnancy, and developed further hypertension during the pregnancy (pregnancy-aggravated hypertension; Group B). A LAC coagulation assay was performed, and the presence of LAC in each group was compared. All 14 patients in group A were LAC-negative. In contrast, 3 of the 6 patients in group B were LAC-positive, and had clinical autoimmune diseases. The incidence of pregnancy-induced hypertension was also examined in 15 pregnancies from 9 LAC-positive women who had a history of repeated fetal loss but no systemic autoimmune disease (Group C). None of these 15 pregnancies had hypertensive complications, even when they reached term. In the placentas of LAC-positive women, no characteristic changes other than fibrinoid degeneration and microscopic infarction were observed upon histological examination. These results suggest that LAC does not relate with the onset of hypertension during pregnancy.

  19. BL LAC PKSB1144-379 an extreme scintillator

    CERN Document Server

    Turner, R J; Shabala, S S; Blanchard, J; Lovell, J E J; McCallum, J N; Cimo, G

    2012-01-01

    Rapid variability in the radio flux density of the BL Lac object PKSB1144-379 has been observed at four frequencies, ranging from 1.5 to 15 GHz, with the VLA and the University of Tasmania's Ceduna antenna. Intrinsic and line of sight effects were examined as possible causes of this variability, with interstellar scintillation best explaining the frequency dependence of the variability timescales and modulation indices. This scintillation is consistent with a compact source 20-40 microarcseconds, or 0.15-0.3 pc in size. The inferred brightness temperature for PKSB1144-379 (assuming that the observed variations are due to scintillation) is 6.2e12 K at 4.9 GHz, with approximately 10 percent of the total flux in the scintillating component. We show that scintillation surveys aimed at identifying variability timescales of days to weeks are an effective way to identify the AGN with the highest brightness temperatures.

  20. Photohadronic scenario in interpreting the February-March 2014 flare of 1ES 1011+496

    CERN Document Server

    Sahu, Sarira; Miranda, Luis Salvador

    2016-01-01

    The extraordinary multi-TeV flare from 1ES 1011 +496 during February-March 2014 was observed by MAGIC telescopes for 17 nights and the average spectrum of the whole period has a non-trivial shape. We have used the photohadronic model and a template EBL model to explain the average spectrum which fits well to the flare data. The spectral index $\\alpha$ is the only free parameter in our model. We have also shown that the non-trivial nature of the spectrum is due to the change in the behavior of the optical depth above $\\sim 600$ GeV $\\gamma$-ray energy accompanied with the high SSC flux.

  1. Very Strong 0.3-10 keV Flare in the HBL Source 1ES 1959+650

    Science.gov (United States)

    Kapanadze, Bidzina

    2017-08-01

    Since 2017 June 12, the nearby TeV-detected HBL source 1ES 1959+650 (z=0.048) is showing another cycle of a very strong X-ray flaring activity, which is the fourth since 2015 August (see Kapanadze B. et al. "A recent strong X-ray flaring activity of 1ES 1959+650 with possibly less efficient stochastic acceleration"; ATel#9949,9694,9205,9121,8468,8342, 8289,8014,10439; see http://www.swift.psu.edu/monitoring/source.php?source=1ES1959+650).

  2. BL Lacertae objects and the extragalactic γ-ray background

    Institute of Scientific and Technical Information of China (English)

    Fan Li; Xin-Wu Cao

    2011-01-01

    A tight correlation between γ-ray and radio emission is found for a sample of BL Lacertae (BL Lac) objects detected by the Fermi Gamma-ray Space Telescope (Fermi) and the Energetic Gamma-Ray Experiment Telescope (EGRET).The γ-ray emission of BL Lac objects exhibits strong variability,and the detection rate of γ-ray BL Lac objects is low,which may be related to the γ-ray duty cycle of BL Lac objects.We estimate the γ-ray duty cycle,δγ (≌)0.11,for BL Lac objects detected by EGRET and Fermi.Using the empirical relation ofγ-ray emission with radio emission and the estimated γ-ray duty cycle δγ,we derive the γ-ray luminosity function (LF) of BL Lac objects from their radio LF.Our derived γ-ray LF of BL Lac objects can almost reproduce that calculated with the recently released Fermi bright active galactic nuclei (AGN) sample.Comparison of the derived LF of the γ-ray BL Lac objects in this work with that derived by Abdo et al.(2009a) requires the γ-ray duty cycle of BL Lac objects to be almost luminosity-independent.We find that ~ 45% of the extragalactic diffuse γ-ray background (EGRB) is contributed by BL Lac objects.Combining the estimate of the quasar contribution to the EGRB in the previous work,we find that ~ 77% of the EGRB is contributed by BL Lac objects and radio quasars.

  3. Detection of VHE gamma-ray emission from the distant blazar 1ES 1101-232 with H.E.S.S. and broadband characterisation

    CERN Document Server

    Akhperjanian, A G; Beilicke, M; Benbow, W; Berge, D; Bernlöhr, K; Boisson, C; Bolz, O; Borrel, V; Braun, I; Brion, E; Brown, A M; Buhler, R; Büsching, I; Boutelier, T; Carrigan, S; Chadwick, P M; Chounet, L M; Coignet, G; Cornils, R; Costamante, L; Degrange, B; Dickinson, H J; Djannati-Atai, A; O'Connor-Drury, L; Dubus, G; Egberts, K; Emmanoulopoulos, D; Espigat, P; Farnier, C; Feinstein, F; Ferrero, E; Fiasson, A; Fontaine, G; Funk, Seb; Funk, S; Fussling, M; Gallant, Y A; Giebels, B; Glicenstein, J F; Glück, B; Goret, P; Hadjichristidis, C; Hauser, D; Hauser, M; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hoffmann, A; Hofmann, W; Holleran, M; Hoppe, S; Horns, D; Jacholkowska, A; De Jager, O C; Kendziorra, E; Kerschhaggl, M; Khelifi, B; Komin, Nu; Kosack, K; Lamanna, G; Latham, I J; Le Gallou, R; Lemiere, A; Lemoine-Goumard, M; Lohse, T; Martin, J M; Martineau-Huynh, O; Marcowith, A; Masterson, C; Maurin, G; McComb, T J L; Moulin, E; De Naurois, Mathieu; Nedbal, D; Nolan, S J; Noutsos, A; Olive, J P; Orford, K J; Osborne, J L; Panter, M; Pelletier, G; Petrucci, P O; Pita, S; Pühlhofer, G; Punch, M; Ranchon, S; Raubenheimer, B C; Raue, M; Rayner, S M; Ripken, J; Rob, L; Rolland, L; Rosier-Lees, S; Rowell, G; Sahakian, V V; Santangelo, A; Sauge, L; Schlenker, S; Schlickeiser, R; Schroder, R; Schwanke, U; Schwarzburg, S; Schwemmer, S; Shalchi, A; Sol, H; Spangler, D; Spanier, F; Steenkamp, R; Stegmann, C; Superina, G; Tam, P H; Tavernet, J P; Terrier, R; Tluczykont, M; Van Eldik, C; Vasileiadis, G; Venter, C; Vialle, J P; Vincent, P; Völk, H J; Wagner, S J; Ward, M

    2007-01-01

    The blazar 1ES 1101-232 was observed with the High Energy Stereoscopic System (H.E.S.S.) of Atmospheric Cherenkov Telescopes (ACT) in 2004 and 2005, for a live time of 43 hours. VHE (E > 10^11 eV) gamma-rays were detected for the first time from this object. VHE observations of blazars are used to investigate the inner parts of the blazar jets, and also to study the extragalactic background light (EBL) in the near-infrared band. Observations in 2005 were conducted in a multiwavelength campaign, together with the RXTE satellite and optical observations. In 2004, simultaneous observations with XMM-Newton were obtained. 1ES 1101-232 was detected with H.E.S.S. with an excess of 722 photons, at a significance of 12 sigma. The measured VHE gamma-ray flux amounts to dN/dE = (5.63 +- 0.89) x 10^-13 (E/TeV)^-(2.94 +- 0.20) cm^-2 s^-1 TeV^-1, above a spectral energy threshold of 225 GeV. No significant variation of the VHE gamma-ray flux on any time scale was found. 1ES 1101-232 exhibits a very hard spectrum, and at a ...

  4. The Energy Landscape of Hyperstable LacI-DNA Loops

    Science.gov (United States)

    Kahn, Jason

    2009-03-01

    The Escherichia coli LacI protein represses transcription of the lac operon by blocking access to the promoter through binding at a promoter-proximal DNA operator. The affinity of tetrameric LacI (and therefore the repression efficiency) is enhanced by simultaneous binding to an auxiliary operator, forming a DNA loop. Hyperstable LacI-DNA loops were previously shown to be formed on DNA constructs that include a sequence-directed bend flanked by operators. Biochemical experiments showed that two such constructs (9C14 and 11C12) with different helical phasing between the operators and the DNA bend form different DNA loop shapes. The geometry and topology of the loops and the relevance of alternative conformations suggested by probable flexible linkers in LacI remain unclear. Bulk and single molecule fluorescence resonance energy transfer (SM-FRET, with D. English) experiments on a dual fluorophore-labeled 9C14-LacI loop demonstrate that it adopts a single, stable, rigid closed-form loop conformation. Here, we characterize the LacI-9C14 loop by SM-FRET as a function of inducer isopropyl-β,D-thiogalactoside (IPTG) concentration. Energy transfer measurements reveal partial but incomplete destabilization of loop formation by IPTG. Surprisingly, there is no change in the energy transfer efficiency of the remaining looped population. Models for the regulation of the lac operon often assume complete disruption of LacI-operator complexes upon inducer binding to LacI. Our work shows that even at saturating IPTG there is still a significant population of LacI-DNA complexes in a looped state, in accord with previous in vivo experiments that show incomplete induction (with J. Maher). Finally, we will report progress on characterizing the ``energy landscape'' for DNA looping upon systematic variation of the DNA linkers between the operators and the bending locus. Rod mechanics simulations (with N. Perkins) provide testable predictions on loop stability, topology, and FRET.

  5. LacR Is a Repressor of lacABCD and LacT Is an Activator of lacTFEG, Constituting the lac Gene Cluster in Streptococcus pneumoniae

    NARCIS (Netherlands)

    Afzal, Muhammad; Shafeeq, Sulman; Kuipers, Oscar P.

    2014-01-01

    Comparison of the transcriptome of Streptococcus pneumoniae strain D39 grown in the presence of either lactose or galactose with that of the strain grown in the presence of glucose revealed the elevated expression of various genes and operons, including the lac gene cluster, which is organized into

  6. Baseline surveys of Lac Bay benthic and fish communities, Bonaire

    NARCIS (Netherlands)

    Debrot, A.O.; Hylkema, A.; Vogelaar, W.; Meesters, H.W.G.; Engel, M.S.; Leon, R.; Prud'homme van Reine, W.F.; Nagelkerken, I.

    2012-01-01

    Lac Bay is a clear-water, 5 m deep shallow tropical lagoon of 7 km2 opening onto the wave and wind exposed east coast of the island of Bonaire, southern Caribbean. Over the last decades land reclamation by mangroves in Lac has been expanding the surface of turbid, saline backwaters into the bay at a

  7. BL Lacertae Objects and the Extragalactic Gamma-Ray Background

    CERN Document Server

    Li, Fan

    2011-01-01

    A tight correlation between gamma-ray and radio emission is found for a sample of BL Lacertae (BL Lac) objects detected by Fermi Gamma-ray Space Telescope (Fermi) and the Energetic Gamma-Ray Experiment Telescope (EGRET). The gamma-ray emission of BL Lac objects exhibits strong variability, and the detection rate of gamma-ray BL Lac objects is low, which may be related to the gamma-ray duty cycle of BL Lac objects. We estimate the gamma-ray duty cycle ~ 0.11, for BL Lac objects detected by EGRET and Fermi. Using the empirical relation of gamma-ray emission with radio emission and the estimated gamma-ray duty cycle, we derive the gamma-ray luminosity function (LF) of BL Lac objects from their radio LF. Our derived gamma-ray LF of BL Lac objects can almost reproduce that calculated with the recently released Fermi bright active galactic nuclei (AGN) sample. We find that about 45% of the extragalactic diffuse gamma-ray background (EGRB) is contributed by BL Lac objects. Combining the estimate of the quasar contri...

  8. Multiwavelength Observations of 1ES 1959+650, One Year After the Strong Outburst of 2002

    CERN Document Server

    Gutíerrez, K; Bradbury, S M; Buckley, J H; Celik, O; Chow, Y C; Cogan, P; Cui, W; Daniel, M; Falcone, A; Fegan, S J; Finley, J P; Gillanders, G H; Grube, J; Holder, J; Horan, D; Hughes, S B; Jung, I; Kieda, D; Kosack, K; Krawczynski, H; Krennrich, F; Lang, M J; Le Bohec, S; Maier, G; Moriarty, P; Perkins, J; Pohl, M; Quinn, J; Rebillot, P F; Rose, H J; Schroedter, M; Sembroski, G H; Wakely, S P; Weekes, T C; White, R J

    2006-01-01

    In April-May 2003, the blazar 1ES 1959+650 showed an increased level of X-ray activity. This prompted a multiwavelength observation campaign with the Whipple 10 m gamma-ray telescope, the Rossi X-ray Timing Explorer, the Bordeaux Optical Observatory, and the University of Michigan Radio Astrophysical Observatory. We present the multiwavelength data taken from May 2, 2003 to June 7, 2003 and compare the source characteristics with those measured during observations taken during the years 2000 and 2002. The X-ray observations gave a data set with high signal-to-noise light curves and energy spectra; however, the gamma-ray observations did not reveal a major TeV gamma-ray flare. Furthermore, we find that the radio and optical fluxes do not show statistically significant deviations from those measured during the 2002 flaring periods. While the X-ray flux and X-ray photon index appear correlated during subsequent observations, the apparent correlation evolved significantly between the years 2000, 2002, and 2003. W...

  9. Long-term optical polarization variability of the tev blazar 1es~1959+650

    CERN Document Server

    Sorcia, Marco; Hiriart, David; López, José M; Cabrera, José I; Mújica, Raúl; Heidt, Jochen; Agudo, Ivan; Nilsson, Kari; Mommert, Michael

    2013-01-01

    A detailed analysis of the optical polarimetric variability of the TeV blazar 1ES 1959+650 from 2007 October 18 to 2011 May 5 is presented. The source showed a maximum and minimum brightness states in the R-band of 14.08$\\pm$0.03 mag and 15.20$\\pm$0.03 mag, respectively, with a maximum variation of 1.12 mag, and also a maximum polarization degree of $P=$(12.2$\\pm$0.7)%, with a maximum variation of 10.7%. From August to November 2009, a correlation between the optical $R$-band flux and the degree of linear polarization was found, with a correlation coefficient $r_{pol}$=0.984$\\pm$0.025. The source presented a preferential position angle of optical polarization of $\\sim153^{\\circ}$, with variations of $10\\degr$-$50\\degr$, that is in agreement with the projected position angle of the parsec scale jet found at 43 GHz. From the Stokes parameters we infer the existence of two optically-thin synchrotron components that contribute to the polarized flux. One of them is stable, with a constant polarization degree of 4%...

  10. Evidence of Two-Component Optical Polarization in Blazar 1ES 1959+650

    Science.gov (United States)

    Sorcia, Marco; Benítez, Erika; Hiriart, David

    2013-12-01

    In this work we present an analysis of the optical polarimetric variability of the TeV-blazar 1 ES 1959+650 from 2007 October 18 to 2011 May 5. The source showed a maximum variation of 1.2 mag in R- band, and a maximum polarization degree of 12.2%. The blazar presented a preferential position angle of the optical polarization of ~ 153°, with variations of 10° - 50°, which is in agreement with the projected position angle of the parsec-scale jet found at 43 GHz. We infer the existence of the two optically thin synchrotron components that contribute to the polarized flux, consistent with the spine-sheath model. One of them is stable with a constant polarization degree of 4%. Assuming a stationary shock, we estimated some parameters associated with the physics of the relativistic jet: the Doppler factor of δD ˜ 23, the viewing angle of the jet of Φ ~ 2°.4, and the size of the emission region of rb ~ 5.6 × 1017 cm.

  11. Investigating Broadband Variability of the TeV Blazar 1ES 1959+650

    CERN Document Server

    Aliu, E; Arlen, T; Aune, T; Barnacka, A; Beilicke, M; Benbow, W; Berger, K; Bird, R; Bouvier, A; Buckley, J H; Bugaev, V; Cerruti, M; Chen, X; Ciupik, L; Collins-Hughes, E; Connolly, M P; Cui, W; Dumm, J; Eisch, J D; Falcone, A; Federici, S; Feng, Q; Finley, J P; Fleischhack, H; Fortin, P; Fortson, L; Furniss, A; Galante, N; Gillanders, G H; Griffin, S; Griffiths, S T; Grube, J; Gyuk, G; Hakansson, N; Hanna, D; Holder, J; Hughes, G; Humensky, T B; Johnson, C A; Kaaret, P; Kar, P; Kertzman, M; Khassen, Y; Kieda, D; Krawczynski, H; Krennrich, F; Lang, M J; Madhavan, A S; Majumdar, P; McArthur, S; McCann, A; Meagher, K; Millis, J; Moriarty, P; Mukherjee, R; Nelson, T; Nieto, D; de Bhroithe, A O'Faolain; Ong, R A; Otte, A N; Park, N; Perkins, J S; Pohl, M; Popkow, A; Prokoph, H; Quinn, J; Ragan, K; Rajotte, J; Reyes, L C; Reynolds, P T; Richards, G T; Roache, E; Sadun, A; Santander, M; Sembroski, G H; Shahinyan, K; Sheidaei, F; Smith, A W; Staszak, D; Telezhinsky, I; Theiling, M; Tyler, J; Varlotta, A; Vassiliev, V V; Vincent, S; Wakely, S P; Weekes, T C; Weinstein, A; Welsing, R; Wilhelm, A; Williams, D A; Zitzer, B; Böttcher, M; Fumagalli, M

    2014-01-01

    We summarize broadband observations of the TeV-emitting blazar 1ES 1959+650, including optical R-band observations by the robotic telescopes Super-LOTIS and iTelescope, UV observations by Swift UVOT, X-ray observations by the Swift X-ray Telescope (XRT), high-energy gamma-ray observations with the Fermi Large Area Telescope (LAT) and very-high-energy (VHE) gamma-ray observations by VERITAS above 315 GeV, all taken between 17 April 2012 and 1 June 2012 (MJD 56034 and 56079). The contemporaneous variability of the broadband spectral energy distribution is explored in the context of a simple synchrotron self Compton (SSC) model. In the SSC emission scenario, we find that the parameters required to represent the high state are significantly different than those in the low state. Motivated by possible evidence of gas in the vicinity of the blazar, we also investigate a reflected-emission model to describe the observed variability pattern. This model assumes that the non-thermal emission from the jet is reflected b...

  12. VizieR Online Data Catalog: The CLASS BL Lac sample (Marcha+, 2013)

    Science.gov (United States)

    Marcha, M. J. M.; Caccianiga, A.

    2014-04-01

    This paper presents a new sample of BL Lac objects selected from a deep (30mJy) radio survey of flat spectrum radio sources (the CLASS blazar survey). The sample is one of the largest well-defined samples in the low-power regime with a total of 130 sources of which 55 satisfy the 'classical' optical BL Lac selection criteria, and the rest have indistinguishable radio properties. The primary goal of this study is to establish the radio luminosity function (RLF) on firm statistical ground at low radio luminosities where previous samples have not been able to investigate. The gain of taking a peek at lower powers is the possibility to search for the flattening of the luminosity function which is a feature predicted by the beaming model but which has remained elusive to observational confirmation. In this study, we extend for the first time the BL Lac RLF down to very low radio powers ~1022W/Hz, i.e. two orders of magnitude below the RLF currently available in the literature. In the process, we confirm the importance of adopting a broader, and more physically meaningful set of classification criteria to avoid the systematic missing of low-luminosity BL Lacs. Thanks to the good statistics we confirm the existence of weak but significant positive cosmological evolution for the BL Lac population, and we detect, for the first time the flattening of the RLF at L~1025W/Hz in agreement with the predictions of the beaming model. (1 data file).

  13. The Sedentary Survey of Extreme High Energy Peaked BL Lacs III. Results from Optical Spectroscopy

    CERN Document Server

    Piranomonte, S; Giommi, P; Landt, H; Padovani, P

    2007-01-01

    The multi-frequency Sedentary Survey is a flux limited, statistically well-defined sample of highly X-ray dominated BL Lacertae objects (HBLs) which includes 150 sources. In this paper, the third of the series, we report the results of a dedicated optical spectroscopy campaign that, together with results from other independent optical follow up programs, led to the spectroscopic identification of all sources in the sample. We carried out a systematic spectroscopic campaign for the observation of all unidentified objects of the sample using the ESO 3.6m, the KPNO 4m, and the TNG optical telescopes. We present new identifications and optical spectra for 76 sources, 50 of which are new BL Lac objects, 18 are sources previously referred as BL Lacs but for which no redshift information was available, and 8 are broad emission lines AGNs. We find that the multi-frequency selection technique used to build the survey is highly efficient (about 90%) in selecting BL Lacs objects. We present positional and spectroscopic ...

  14. The REX survey as a tool to test the beaming model for BL Lacs

    CERN Document Server

    Caccianiga, A; MacCacaro, T; Wolter, A; Gioia, I M

    1999-01-01

    In the context of the beaming model (BM) BL Lac and FR I radio galaxies are thought to be the same class of sources seen at different angles. If this picture is correct, we expect to find some transition objects with intermediate properties between the two classes. To date, this intermediate population of objects is missing, probably due to the limiting fluxes of the current X-ray/radio surveys and/or to the criteria used to separate BL Lacs from normal elliptical galaxies. As pointed out by Browne and Marcha (1993), the detection of the transition objects requires particular attention since the "weak" BL Lac nucleus is hidden by the light of the host elliptical galaxy. A useful criterion often used to assess the presence of a non-thermal source, in addition to the stellar emission of the host galaxy, is the Ca contrast at 4000 AA (K/sub 4000/). This quantity, which is defined as the relative depression of the spectrum across 4000 AA, is a typical feature observed in a "normal" elliptical galaxy; the samples ...

  15. Adsorption Properties of Lac Dyes on Wool, Silk, and Nylon

    Directory of Open Access Journals (Sweden)

    Bo Wei

    2013-01-01

    Full Text Available There has been growing interest in the dyeing of textiles with natural dyes. The research about the adsorption properties of natural dyes can help to understand their adsorption mechanism and to control their dyeing process. This study is concerned with the kinetics and isotherms of adsorption of lac dyes on wool, silk, and nylon fibers. It was found that the adsorption kinetics of lac dyes on the three fibers followed the pseudosecond-order kinetic model, and the adsorption rate of lac dyes was the fastest for silk and the slowest for wool. The activation energies for the adsorption process on wool, silk, and nylon were found to be 107.15, 87.85, and 45.31 kJ/mol, respectively. The adsorption of lac dyes on the three fibers followed the Langmuir mechanism, indicating that the electrostatic interactions between lac dyes and those fibers occurred. The saturation values for lac adsorption on the three fibers decreased in the order of wool > silk > nylon; the Langmuir affinity constant of lac adsorption on nylon was much higher than those on wool and silk.

  16. The Sedentary Multi-Frequency Survey; 1, Statistical Identification and Cosmological Properties of HBL BL Lacs

    CERN Document Server

    Giommi, P; Padovani, P

    1999-01-01

    We have assembled a multi-frequency database by cross-correlating the NVSS catalog of radio sources with the RASSBSC list of soft X-ray sources, obtaining optical magnitude estimates from the Palomar and UK Schmidt surveys as provided by the APM and COSMOS on-line services. By exploiting the nearly unique broad-band properties of High-Energy Peaked (HBL) BL Lacs we have statistically identified a sample of 218 objects that is expected to include about 85% of BL Lacs and that is therefore several times larger than all other published samples of HBLs. Using a subset (155 objects) that is radio flux limited and statistically well-defined we have derived the \\vovm distribution and the LogN-LogS of extreme HBLs (fx/fr >= 3E-10 erg/cm2/s/Jansky) down to 3.5 mJy. We find that the LogN-LogS flattens around 20 mJy and that = 0.42 +/- 0.02. This extends to the radio band earlier results, based on much smaller X-ray selected samples, about the anomalous cosmological observational properties of HBL BL Lacs. A comparison...

  17. Land use plan : Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this land use plan for Des Lacs National Wildlife Refuge is to outline the principal practices and procedures necessary to establish a reasonable...

  18. [Wildlife inventory plan : Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This wildlife inventory plan describes methods for collecting migratory birds, upland birds, big game, predator, and small mammal surveys at Des Lacs National...

  19. Botulism on the Des Lacs Refuge and control measures

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Report on botulism at Des Lacs National Wildlife Refuge. Summaries of botulism outbreaks on the refuge for 1935-1937 are included, as well as information on...

  20. Narrative report calendar year 1970 Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1970 calendar year. The report begins by summarizing...

  1. Narrative report calendar year 1967 Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1967 calendar year. The report begins by summarizing...

  2. Narrative report calendar year 1969 Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1969 calendar year. The report begins by summarizing...

  3. Narrative report calendar year 1965 Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1965 calendar year. The report begins by summarizing...

  4. Preliminary fishery management report : Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — A study of fishery management at Des Lacs National Wildlife Refuge was conducted from June 18 to 20, 1952. This brief preliminary report will serve to highlight the...

  5. Narrative report calendar year 1964 Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1964 calendar year. The report begins by summarizing...

  6. Narrative report calendar year 1966 Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1966 calendar year. The report begins by summarizing...

  7. Cloning and expression of Kluyveromyces fragilis LAC4 gene

    Institute of Scientific and Technical Information of China (English)

    霍克克; 李育阳

    1995-01-01

    The genomic library of Kluyveromyces fragilis was constructed in E.coli TG1,and 5β-galactosidase gene(LAC4)clones have been obtained from the library by complementation of theKluyveromyces lactis lac4-8 mutation.The studies on the structure and the function of the LAC4 gene revealedthat(i)the gene can also complement E.coli lacZ mutation;(ii)the physical map of the K.fragilis LAC4gene was very similar to that of K.lactis;(iii)the β-galactosidase levels expressed by the clone strains weremuch higher than that expressed by the original strain;(iv)the variation of the β-galactosidase level of differ-ent clone strains induced by lactose or galactose was related to the retained degree of the 5’ flanking region ofLAC4 gene,suggesting that there migth he a lactose specific transcription activating element in the region.

  8. Extreme Blazars Studied with Fermi-LAT and Suzaku: 1ES 0347-121 and Blazar Candidate HESS J1943+213

    CERN Document Server

    Tanaka, Y T; Finke, J; Cheung, C C; Dermer, C D; Kataoka, J; Bamba, A; Dubus, G; De Naurois, M; Wagner, S J; Fukazawa, Y; Thompson, D J

    2014-01-01

    We report on our study of high-energy properties of two peculiar TeV emitters: the "extreme blazar" 1ES 0347-121 and the "extreme blazar candidate" HESS J1943+213 located near the Galactic Plane. Both objects are characterized by quiescent synchrotron emission with flat spectra extending up to the hard X-ray range, and both were reported to be missing GeV counterparts in the Fermi-LAT 2-year Source Catalog. We analyze a 4.5 year accumulation of the Fermi-LAT data, resulting in the detection of 1ES 0347-121 in the GeV band, as well as in improved upper limits for HESS J1943+213. We also present the analysis results of newly acquired Suzaku data for HESS J1943+213. The X-ray spectrum is well represented by a single power law extending up to 25 keV with photon index 2.00+/-0.02 and a moderate absorption in excess of the Galactic value, in agreement with previous X-ray observations. No short-term X-ray variability was found over the 80 ks duration of the Suzaku exposure. Under the blazar hypothesis, we modeled th...

  9. New mutation detection system of repackaged λ gt11 DNA containing LacZ gene

    Institute of Scientific and Technical Information of China (English)

    LIU Yong; CAO Jia; WU Tao; YANG Lu-jun; SUN Hua-ming; YANG Ming-jie; QIAN Ping

    2002-01-01

    Objective: To establish a reformative detection system which has sound ability of providing information on molecular mutagenesis spectrum and the specificity of detection system of repackaged λ phage.Methods: LacZ gene, as mutational target gene and reporter gene, was applied into the detection system.The λ gt11 DNA treated with ENU (1-ethyl-1-nitrosourea) and 9-AA (9-aminoacridine) was repackaged in vitro. The packaged λ phage was then grown in E. coli Y1090 on a selective plate containing X-gel and IPTG. The survival and mutation frequencies were determined by counting the clear-plaque and blue-plaque,and the molecular mutation mechanism was studied by extracting and sequencing the LacZ gene of mutants.Results: The survival of repackaged λ phages treated with 9-AA and ENU apparently decreased in consistent dose-dependence. The mutation frequency of clear-plaque mutants showed a linear dose-related increase. The predominant mutations induced by 9-AA were ±1 frameshift mutation, and 9-AA induced -1 frameshift was much more effective than induced + 1 frameshift. 9-AA also induced substitutions with transversions more common. ENU-induced mutations were chiefly occurred at G: C sites. Substitutions induced by ENU were mainly G: C→A: T, G: C→C: G and A: T→T: A transversion. Conclusion: Mutation detection system of λgt11 DNA containing LacZ gene is proven better than that of λDNA without LacZ gene. The combination of survival, mutant frequency and sequence spectrum can not only increase the sensitivity and specificity of the new method, but also provide a better understanding of the molecular mechanism of mutation for ultimate extrapolation to risk assessment.

  10. 油桐LACS4和LACS8基因克隆及其表达分析%Isolation and Expression Analysis of LACS4 and LACS8 from Vernicia fordii

    Institute of Scientific and Technical Information of China (English)

    李捷宇; 龙洪旭; 张琳; 王哲; 李泽; 谭晓风

    2015-01-01

    以油桐的近成熟种子为材料,根据油桐转录组测序结果设计引物,采用RT-P C R技术克隆了油桐长链脂酰辅酶A合成酶基因家族的两个成员的全长cDNA序列,分别命名为VfLACS4(GenBank登录号:KP996689)和VfLACS8(GenBank登录号:KT362743),通过实时定量PCR的方法检测了不同组织部位和种子不同发育时期该基因的表达水平,并采用索式提取法测定了种子发育时期的油脂含量。结果表明:VfLACS4的CDS长度为1989 bp,编码662个氨基酸,与其他物种的LACS4氨基酸序列具有较高的相似性,其中与蓖麻的LACS4相似性最高;VfLACS8的CDS长度为2199 bp,编码732个氨基酸,与麻疯树和蓖麻的LACS8具有较高的相似性;实时定量RT-PCR结果表明VfLACS4基因在花、茎、叶和根中均有少量表达,并在种子发育的10月10日表达量达到最大;VfLACS8基因在种子、花、茎、叶和根中均有一定量的表达,在雌蕊中的表达量最高;油桐种子发育过程中的油脂积累呈现出“S”型, VfLACS8基因的在发育种子中的表达模式与之相一致,推测VfLACS8基因与种子发育过程中的油脂积累相关。%Primers were designed according to the results of the transcriptome sequencing analysis of Vernicia fordii, two LACS family members named VfLACS4 and VfLACS8 were isolated from nearly ripe seed in Verni-cia fordii with the method of RT-PCR. Their expression in different tissues and different developmental stages of seed was checked with qRT-PCR. The oil content of different developmental stages of seed was determined by soxhlet extraction. The CDS of VfLACS4 is 1 989 bp which codes a predicted protein of 662 amino acids. The amino acid identity compared with others is highly conserved and showed the highest similarity with the LACS4 of Ricinus communis. The CDS of VfLACS8 is 2 199 bp which codes a predicted protein of 732 amino acids. The amino acid identity compared with others is highly conserved

  11. Arabidopsis CER8 encodes LONG-CHAIN ACYL-COA SYNTHETASE 1 (LACS1) that has overlapping functions with LACS2 in plant wax and cutin synthesis.

    Science.gov (United States)

    Lü, Shiyou; Song, Tao; Kosma, Dylan K; Parsons, Eugene P; Rowland, Owen; Jenks, Matthew A

    2009-08-01

    Plant cuticle is an extracellular lipid-based matrix of cutin and waxes, which covers aerial organs and protects them from many forms of environmental stress. We report here the characterization of CER8/LACS1, one of nine Arabidopsis long-chain acyl-CoA synthetases thought to activate acyl chains. Mutations in LACS1 reduced the amount of wax in all chemical classes on the stem and leaf, except in the very long-chain fatty acid (VLCFA) class wherein acids longer than 24 carbons (C(24)) were elevated more than 155%. The C(16) cutin monomers on lacs1 were reduced by 37% and 22%, whereas the C(18) monomers were increased by 28% and 20% on stem and leaf, respectively. Amounts of wax and cutin on a lacs1-1 lacs2-3 double mutant were much lower than on either parent, and lacs1-1 lacs2-3 had much higher cuticular permeability than either parent. These additive effects indicate that LACS1 and LACS2 have overlapping functions in both wax and cutin synthesis. We demonstrated that LACS1 has synthetase activity for VLCFAs C(20)-C(30), with highest activity for C(30) acids. LACS1 thus appears to function as a very long-chain acyl-CoA synthetase in wax metabolism. Since C(16) but not C(18) cutin monomers are reduced in lacs1, and C(16) acids are the next most preferred acid (behind C(30)) by LACS1 in our assays, LACS1 also appears to be important for the incorporation of C(16) monomers into cutin polyester. As such, LACS1 defines a functionally novel acyl-CoA synthetase that preferentially modifies both VLCFAs for wax synthesis and long-chain (C(16)) fatty acids for cutin synthesis.

  12. Phosphorylation of Streptococcus salivarius lactose permease (LacS) by HPr(His ~ P) and HPr(Ser-P)(His ~ P) and effects on growth.

    Science.gov (United States)

    Lessard, Christian; Cochu, Armelle; Lemay, Jean-Dominique; Roy, Denis; Vaillancourt, Katy; Frenette, Michel; Moineau, Sylvain; Vadeboncoeur, Christian

    2003-12-01

    The oral bacterium Streptococcus salivarius takes up lactose via a transporter called LacS that shares 95% identity with the LacS from Streptococcus thermophilus, a phylogenetically closely related organism. S. thermophilus releases galactose into the medium during growth on lactose. Expulsion of galactose is mediated via LacS and stimulated by phosphorylation of the transporter by HPr(His approximately P), a phosphocarrier of the phosphoenolpyruvate:sugar phosphotransferase transport system (PTS). Unlike S. thermophilus, S. salivarius grew on lactose without expelling galactose and took up galactose and lactose concomitantly when it is grown in a medium containing both sugars. Analysis of the C-terminal end of S. salivarius LacS revealed a IIA-like domain (IIA(LacS)) almost identical to the IIA domain of S. thermophilus LacS. Experiments performed with purified proteins showed that S. salivarius IIA(LacS) was reversibly phosphorylated on a histidine residue at position 552 not only by HPr(His approximately P) but also by HPr(Ser-P)(His approximately P), a doubly phosphorylated form of HPr present in large amounts in rapidly growing S. salivarius cells. Two other major S. salivarius PTS proteins, IIAB(L)(Man) and IIAB(H)(Man), were unable to phosphorylate IIA(LacS). The effect of LacS phosphorylation on growth was studied with strain G71, an S. salivarius enzyme I-negative mutant that cannot synthesize HPr(His approximately P) or HPr(Ser-P)(His approximately P). These results indicated that (i) the wild-type and mutant strains had identical generation times on lactose, (ii) neither strain expelled galactose during growth on lactose, (iii) both strains metabolized lactose and galactose concomitantly when grown in a medium containing both sugars, and (iv) the growth of the mutant was slightly reduced on galactose.

  13. The use of lac-type promoters in control analysis

    DEFF Research Database (Denmark)

    Jensen, Peter Ruhdal; Westerhoff, H. v.; Michelsen, Ole

    1993-01-01

    For control analysis, it is necessary to modulate the activity of an enzyme around its normal level and measure the changes in steady-state fluxes or concentrations. We describe an improved method for effecting the modulation, as elaborated for Escherichia coli. The chromosomal gene, encoding...... the enzyme of interest, is put under the control of a lacUV5 or a tacI promoter. The alternative use of the two promoters leads to an expression range which should make it suitable for the use in control analysis of many enzymes. The lacUV5 promoter should be used when the wild-type expression level is low......, the tacI promoter when the latter is high. The endogenous lac operon is placed under the control of a second copy of the lacUV5 promoter and a lacYam mutation (eliminating lactose permease, the transport system for the inducer isopropyl-thio-beta-D-galactoside) is introduced. The method was demonstrated...

  14. A Search for Low-Luminosity BL Lacertae Objects

    CERN Document Server

    Rector, T A; Perlman, E S; Rector, Travis A.; Stocke, John T.; Perlman, Eric S.

    1999-01-01

    Many properties of BL Lacs have become explicable in terms of the "relativistic beaming" hypothesis whereby BL Lacs are FR-1 radio galaxies viewed nearly along the jet axis. However, a possible problem with this model is that a transition population between beamed BL Lacs and unbeamed FR-1s has not been detected. A transition population of "low-luminosity BL Lacs" was predicted to exist in abundance in X-ray-selected samples such as the Einstein Extended Medium Sensitivity Survey (EMSS) by Browne & Marcha. However, these BL Lacs may have been misidentified as clusters of galaxies. We have conducted a search for such objects in the EMSS with the ROSAT HRI; and here we present ROSAT HRI images, optical spectra and VLA radio maps for a small number of BL Lacs which were previously misidentified in the EMSS catalog as clusters of galaxies. While these objects are slightly lower in luminosity than other EMSS BL Lacs, their properties are too similar to the other BL Lacs in the EMSS sample to "bridge the gap" b...

  15. A three-year multi-wavelength study of the very-high-energy γ-ray blazar 1ES 0229+200

    Energy Technology Data Exchange (ETDEWEB)

    Aliu, E. [Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States); Archambault, S. [Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada); Arlen, T.; Aune, T. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Behera, B.; Chen, X. [DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Beilicke, M.; Buckley, J. H.; Bugaev, V. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Benbow, W.; Cerruti, M. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Berger, K. [Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware, Newark, DE 19716 (United States); Bird, R. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Bouvier, A. [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States); Byrum, K. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Connolly, M. P. [School of Physics, National University of Ireland Galway, University Road, Galway (Ireland); Cui, W. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Duke, C. [Department of Physics, Grinnell College, Grinnell, IA 50112-1690 (United States); Dumm, J., E-mail: mcerruti@cfa.harvard.edu, E-mail: jeremy.s.perkins@nasa.gov [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); and others

    2014-02-10

    The high-frequency-peaked BL Lacertae object 1ES 0229+200 is a relatively distant (z = 0.1396), hard-spectrum (Γ ∼ 2.5), very-high-energy (VHE; E > 100 GeV) emitting γ-ray blazar. VHE measurements of this active galactic nucleus have been used to place constraints on the intensity of the extragalactic background light and the intergalactic magnetic field (IGMF). A multi-wavelength study of this object centered around VHE observations by Very Energetic Radiation Imaging Telescope Array System (VERITAS) is presented. This study obtained, over a period of three years, an 11.7 standard deviation detection and an average integral flux F(E > 300 GeV) = (23.3 ± 2.8{sub stat} ± 5.8{sub sys}) × 10{sup –9} photons m{sup –2} s{sup –1}, or 1.7% of the Crab Nebula's flux (assuming the Crab Nebula spectrum measured by H.E.S.S). Supporting observations from Swift and RXTE are analyzed. The Swift observations are combined with previously published Fermi observations and the VHE measurements to produce an overall spectral energy distribution which is then modeled assuming one-zone synchrotron-self-Compton emission. The χ{sup 2} probability of the TeV flux being constant is 1.6%. This, when considered in combination with measured variability in the X-ray band, and the demonstrated variability of many TeV blazars, suggests that the use of blazars such as 1ES 0229+200 for IGMF studies may not be straightforward and challenges models that attribute hard TeV spectra to secondary γ-ray production along the line of sight.

  16. Dynamic model of gene regulation for the lac operon

    Energy Technology Data Exchange (ETDEWEB)

    Angelova, Maia; Ben-Halim, Asma, E-mail: maia.angelova@northumbria.ac.uk, E-mail: asma.benhalim@northumbria.ac.uk [Intelligent Modelling Lab, School of Computing, Engineering and Information Sciences, Northumbria University, Newcastle upon Tyne NE2 1XE (United Kingdom)

    2011-03-01

    Gene regulatory network is a collection of DNA which interact with each other and with other matter in the cell. The lac operon is an example of a relatively simple genetic network and is one of the best-studied structures in the Escherichia coli bacteria. In this work we consider a deterministic model of the lac operon with a noise term, representing the stochastic nature of the regulation. The model is written in terms of a system of simultaneous first order differential equations with delays. We investigate an analytical and numerical solution and analyse the range of values for the parameters corresponding to a stable solution.

  17. Lac du Flambeau Band of Lake Superior Chippewa Indians Strategic Energy Plan

    Energy Technology Data Exchange (ETDEWEB)

    Bryan Hoover

    2009-11-16

    This plan discusses the current energy use on the Lac du Flambeau Reservation, the current status of the Tribe's energy program, as well as the issues and concerns with energy on the reservation. This plan also identifies and outlines energy opportunities, goals, and objectives for the Tribe to accomplish. The overall goal of this plan is to address the energy situation of the reservation in a holistic manner for the maximum benefit to the Tribe. This plan is an evolving document that will be re-evaluated as the Tribe's energy situation changes.

  18. BL Lac A New Ultrahigh-Energy Gamma-Ray Source

    CERN Document Server

    Neshpor, Y I; Stepanian, A A; Kalekin, O R; Jogolev, N A; Fomin, V P; Shitov, V G; Neshpor, Yu. I.

    2001-01-01

    The active galactic nucleus BL Lac was observed with the Gt-48 atmospheric Cherenkov detector of the Crimean Astrophysical Observatory from July 23-September 1, 1998, in order to search for ultrahigh-energy gamma-ray (>1 TeV) emission. The object was in the field of view of the detector for more than 24 hours. The source was detected with a high level of confidence (7.2 sigma), with a flux equal to (2.1+/-0.4)x10^{-11} photons cm^{-2}s^{-1}.

  19. New statistical results on the optical IDV data of BL Lac S5 0716+714

    CERN Document Server

    Danila, B; Mocanu, G

    2014-01-01

    This paper reports on the statistical behaviour of the optical IntraDay Variability of BL Lac S5 0716+714. Available IntraDay Variability data in the optical is tested to see whether or not the magnitude is log-normally distributed. It was consistently found that this is not the case. This is in agreement with a previous discussion for data for the same object but in a different observational period. Simultaneously, the spectral slope of the light curves is calculated. The implications of these findings for models which discuss both the location and the source of IntraDay Variability are presented.

  20. Optical variability of the high synchrotron energy peaked blazar 1ES 1959+650 on various time-scales

    Science.gov (United States)

    Zhang, You-Hong; Li, Jia-Chen

    2017-08-01

    We report the results of optical monitoring of the high synchrotron energy peaked blazar (HSP), 1ES 1959+650, performed with the 80-cm optical telescope at Xinglong Optical Observatory in 2010-2016. Our study was focused on the optical variability of the source on diverse time-scales over about 6 yr, which is helpful in understanding the variability mechanisms of blazars. Over 19 nights of intense photometric observations, we obtained 38 intranight light curves in the different bands. Intranight variability was not detected from all of these light curves. However, 1ES 1959+650 exhibited significant variations on the short-term (months) and long-term (years) time-scales. During the whole period of our monitoring, the maximum changes in the brightness of the source was 1.38 ± 0.05 and 1.17 ± 0.03 mag in the B and R waveband, respectively. The larger variability amplitude in the blue band than in the red one is demonstrated by the bluer-when-brighter spectral trend. The B - R colour index showed a change of 0.21 ± 0.06 mag across our monitoring period. The non-detection of intranight variations of 1ES 1959+650 is in agreement with previous observations, showing that the optical fluxes of HSPs are less variable than those of intermediate/low synchrotron energy peaked blazars (ISPs/LSPs) on time-scales of hours. In contrast, the detections of significant short-term and long-term variability of the source suggest that the optical variability of HSPs might not be very different from those of ISPs/LSPs on time-scales of months and years. Finally, we discuss some possible scenarios for the differences and the similarities of optical variability on various time-scales between the two blazar subclasses.

  1. Comprehensive Analysis of Rice Laccase Gene (OsLAC) Family and Ectopic Expression of OsLAC10 Enhances Tolerance to Copper Stress in Arabidopsis

    Science.gov (United States)

    Liu, Qingquan; Luo, Le; Wang, Xiaoxiao; Shen, Zhenguo; Zheng, Luqing

    2017-01-01

    Laccases are encoded by a multigene family and widely distributed in plant genomes where they play roles oxidizing monolignols to produce higher-order lignin involved in plant development and stress responses. We identified 30 laccase genes (OsLACs) from rice, which can be divided into five subfamilies, mostly expressed during early development of the endosperm, growing roots, and stems. OsLACs can be induced by hormones, salt, drought, and heavy metals stresses. The expression level of OsLAC10 increased 1200-fold after treatment with 20 μM Cu for 12 h. The laccase activities of OsLAC10 were confirmed in an Escherichia coli expression system. Lignin accumulation increased in the roots of Arabidopsis over-expressing OsLAC10 (OsLAC10-OX) compared to wild-type controls. After growth on 1/2 Murashige and Skoog (MS) medium containing toxic levels of Cu for seven days, roots of the OsLAC10-OX lines were significantly longer than those of the wild type. Compared to control plants, the Cu concentration decreased significantly in roots of the OsLAC10-OX line under hydroponic conditions. These results provided insights into the evolutionary expansion and functional divergence of OsLAC family. In addition, OsLAC10 is likely involved in lignin biosynthesis, and reduces the uptake of Cu into roots required for Arabidopsis to develop tolerance to Cu. PMID:28146098

  2. On the redshifts of the BL Lac 3FGL J0909.0+2310 and its close companion

    Science.gov (United States)

    Rosa-González, D.; Coutiño de León, S.; Mayya, Y. D.; Carramiñana, A.; Aretxaga, I.; Becerra González, J.; Furniss, A.; Terlevich, E.; Vega, O.; Méndez-Abreu, J.; León Tavares, J.; Longinotti, A. L.; Terlevich, R.

    2017-04-01

    We report on the redshift of the BL Lac object 3FGL J0909.0+2310 based on observations obtained with the OSIRIS Multi-Object Spectrograph (MOS) mounted on the 10.4-m Gran Telescopio Canarias. A redshift of 0.432 ± 0.002 was obtained by the identification of three absorption features (Ca II K&H and the G band) detected in the spectrum of the BL Lac host galaxy. The closest object to the BL Lac at an angular separation of 3.8 arcsec (∼21 kpc at this distance) has a similar redshift of 0.431 ± 0.002. This companion galaxy could be the most likely cause of the nuclear activity as postulated by studies based on more extended data sets and cosmological models. MOS allows us to study the object's neighbourhood within a field of view of approximately 7 × 2 arcmin2 and we find two small groups of galaxies at redshifts 0.28 and 0.39 which are probably not related to the activity of 3FGL J0909.0+2310.

  3. On the Redshifts of the BL Lac 3FGL J0909.0+2310 and its Close Companion

    CERN Document Server

    Rosa-Gonzalez, D; Mayya, Y D; Carramiñana, A; Aretxaga, I; Gonzalez, J Becerra; Furniss, A; Terlevich, E; Vega, O; Mendez-Abreu, J; Tavares, J Leon; Longinotti, A L; Terlevich, R

    2016-01-01

    We report on the redshift of the BL Lac object 3FGL J0909.0+2310 based on observations obtained with the OSIRIS Multi Object Spectrograph (MOS) mounted on the 10.4-m Gran Telescopio Canarias. A redshift of 0.432+/-0.002 was obtained by the identification of three absorption features (CaII K&H and G-band) detected in the spectrum of the BL Lac host galaxy. The closest object to the BL Lac at an angular separation of 3.8" (~21 kpc at this distance) has a similar redshift of 0.431+/-0.002. This companion galaxy could be the most likely cause of the nuclear activity as postulated by studies based on more extended data sets and cosmological models. MOS allows us to study the object's neighbourhood within a field of view of approximately 7'x2' and we find two small groups of galaxies at redshifts 0.28 and 0.39 which are probably not related to the activity of 3FGL~J0909.0+2310.

  4. [Proposal for stocking northern pike on Des Lacs NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Pages 4-6 of this 26 page document contain the actual proposal for stocking northern pike in the north portion of the Upper Lake of the Des Lacs National Wildlife...

  5. 76 FR 68124 - Television Broadcasting Services; Fond du Lac, WI

    Science.gov (United States)

    2011-11-03

    ... [Federal Register Volume 76, Number 213 (Thursday, November 3, 2011)] [Proposed Rules] [Pages 68124-68125] [FR Doc No: 2011-28452] FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 73 [MB Docket No. 09-115, RM-11543; DA 11-1502] Television Broadcasting Services; Fond du Lac, WI AGENCY:...

  6. PRODUCTION HALIEUTIQUE DU LAC FAE (BASSIN DU SAN ...

    African Journals Online (AJOL)

    de F CFA pour les poissons, et environ 5,229 millions de FCFA pour la .... Figure 1 Lac Fae-Localisation geographique, zones de production, secteurs et ... c : embankment dam ; d : water intake for regulating the threshold level of water in the.

  7. A single mutation in the core domain of the lac repressor reduces leakiness

    NARCIS (Netherlands)

    Gatti-Lafranconi, Pietro; Dijkman, Willem; Devenish, Sean RA; Hollfelder, Florian

    2013-01-01

    The lac operon provides cells with the ability to switch from glucose to lactose metabolism precisely when necessary. This metabolic switch is mediated by the lac repressor (LacI), which in the absence of lactose binds to the operator DNA sequence to inhibit transcription. Allosteric rearrangements

  8. On the Spectral Curvature of VHE Blazar 1ES 1011+496: Effect of Spatial Particle Diffusion

    Science.gov (United States)

    Sinha, Atreyee; Sahayanathan, S.; Acharya, B. S.; Anupama, G. C.; Chitnis, V. R.; Singh, B. B.

    2017-02-01

    A detailed multi-epoch study of the broadband spectral behavior of the very high energy (VHE) source 1ES 1011+496 provides us with valuable information regarding the underlying particle distribution. Simultaneous observations of the source at optical/UV/X-ray/γ-ray during three different epochs, as obtained from Swift-UVOT/Swift-XRT/Fermi-LAT, are supplemented with the information available from the VHE telescope array, HAGAR. The long-term flux variability at the Fermi-LAT energies is clearly found to be lognormal. It is seen that the broadband spectral energy distribution of 1ES 1011+496 can be successfully reproduced by synchrotron and synchrotron self Compton emission models. Notably, the observed curvature in the photon spectrum at X-ray energies demands a smooth transition of the underlying particle distribution from a simple power law to a power law with an exponential cutoff, or a smooth broken power law distribution, which may possibly arise when the escape of the particles from the main emission region is energy dependent. Specifically, if the particle escape rate is related to its energy as {E}0.5, then the observed photon spectrum is consistent with the ones observed during the various epochs.

  9. On the spectral curvature of VHE blazar 1ES\\,1011+496: Effect of spatial particle diffusion

    CERN Document Server

    Sinha, Atreyee; Acharya, B S; Anupama, G C; Chitnis, V R; Singh, B B

    2016-01-01

    A detailed multi-epoch study of the broadband spectral behaviour of the very high energy (VHE) source, 1ES\\,1011+496, provides us with valuable information regarding the underlying particle distribution. Simultaneous observations of the source at optical/ UV/ X-ray/ $\\gamma$-ray during three different epochs, as obtained from Swift-UVOT/ Swift-XRT/ Fermi-LAT, are supplemented with the information available from the VHE telescope array, HAGAR. The longterm flux variability at the Fermi-LAT energies is clearly found to be lognormal. It is seen that the broadband spectral energy distribution (SED) of 1ES\\,1011+496 can be successfully reproduced by synchrotron and synchrotron self Compton emission models. Notably, the observed curvature in the photon spectrum at X-ray energies demands a smooth transition of the underlying particle distribution from a simple power law to a power law with an exponential cutoff or a smooth broken power law distribution, which may possibly arise when the escape of the particles from ...

  10. The Hadronic Origin of the Hard Gamma-Ray Spectrum from Blazar 1ES 1101-232

    Science.gov (United States)

    Cao, Gang; Wang, Jiancheng

    2014-03-01

    The very hard γ-ray spectrum from distant blazars challenges the traditional synchrotron self-Compton (SSC) model, which may indicate that there is a contribution from an additional high-energy component beyond the SSC emission. In this paper, we study the possible origin of the hard γ-ray spectrum from distant blazars. We develop a model to explain the hard γ-ray spectrum from blazar 1ES 1101-232. In the model, the optical and X-ray radiation would come from the synchrotron radiation of primary electrons and secondary pairs and the GeV emission would be produced by the SSC process, however, the hard γ-ray spectrum would originate from the decay of neutral pion produced through proton-photon interactions with the synchrotron radiation photons within the jet. Our model can explain the observed spectral energy distribution of 1ES 1101-232 well, especially the very hard γ-ray spectrum. However, our model requires a very large proton power to efficiently produce the γ-ray through proton-photon interactions.

  11. Insights into the emission of the blazar 1ES 1011+496 through unprecedented broadband observations during 2011 and 2012

    CERN Document Server

    Aleksić, J; Antonelli, L A; Antoranz, P; Babic, A; Bangale, P; de Almeida, U Barres; Barrio, J A; González, J Becerra; Bednarek, W; Bernardini, E; Biasuzzi, B; Biland, A; Blanch, O; Bonnefoy, S; Bonnoli, G; Borracci, F; Bretz, T; Carmona, E; Carosi, A; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Caneva, G; De Lotto, B; Wilhelmi, E de O na; Mendez, C Delgado; Di Pierro, F; Prester, D Dominis; Dorner, D; Doro, M; Einecke, S; Eisenacher, D; Elsaesser, D; Fernández-Barral, A; Fidalgo, D; Fonseca, M V; Font, L; Frantzen, K; Fruck, C; Galindo, D; López, R J García; Garczarczyk, M; Terrats, D Garrido; Gaug, M; Godinović, N; noz, A González Mu; Gozzini, S R; Hadasch, D; Hanabata, Y; Hayashida, M; Herrera, J; Hose, J; Hrupec, D; Idec, W; Kadenius, V; Kellermann, H; Knoetig, M L; Kodani, K; Konno, Y; Krause, J; Kubo, H; Kushida, J; La Barbera, A; Lelas, D; Lewandowska, N; Lindfors, E; Lombardi, S; Longo, F; López, M; López-Coto, R; López-Oramas, A; Lorenz, E; Lozano, I; Makariev, M; Mallot, K; Maneva, G; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martínez, M; Mazin, D; Menzel, U; Miranda, J M; Mirzoyan, R; Moralejo, A; Munar-Adrover, P; Nakajima, D; Neustroev, V; Niedzwiecki, A; Rosillo, M Nievas; Nilsson, K; Nishijima, K; Noda, K; Orito, R; Overkemping, A; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, J M; Paredes-Fortuny, X; Persic, M; Poutanen, J; Moroni, P G Prada; Prandini, E; Puljak, I; Reinthal, R; Rhode, W; Ribó, M; Rico, J; Garcia, J Rodriguez; Saito, T; Saito, K; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Shore, S N; Sillanpää, A; Sitarek, J; Snidaric, I; Sobczynska, D; Stamerra, A; Steinbring, T; Strzys, M; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzić, T; Tescaro, D; Teshima, M; Thaele, J; Torres, D F; Toyama, T; Treves, A; Vogler, P; Will, M; Zanin, R; Buson, S; D'Ammando, F; Lähteenmäki, A; Hovatta, T; Kovalev, Y Y; Lister, M L; Max-Moerbeck, W; Mundell, C; Pushkarev, A B; Rastorgueva-Foi, E; Readhead, A C S; Richards, J L; Tammi, J; Sanchez, D A; Tornikoski, M; Savolainen, T; Steele, I

    2016-01-01

    1ES 1011+496 $(z=0.212)$ was discovered in very high energy (VHE, E >100 GeV) $\\gamma$-rays with MAGIC in 2007. The absence of simultaneous data at lower energies led to a rather incomplete characterization of the broadband spectral energy distribution (SED). We study the source properties and the emission mechanisms, probing whether a simple one-zone synchrotron-self-Compton (SSC) scenario is able to explain the observed broadband spectrum. We analyzed VHE to radio data from 2011 and 2012 collected by MAGIC, $Fermi$-LAT, $Swift$, KVA, OVRO, and Mets\\"{a}hovi in addition to optical polarimetry data and radio maps from the Liverpool Telescope and MOJAVE. The VHE spectrum was fit with a simple power law with a photon index of $3.69\\pm0.22$ and a flux above 150 GeV of $(1.46\\pm0.16)\\times10^{-11}$ ph cm$^{-2}$ s$^{-1}$. 1ES 1011+496 was found to be in a generally quiescent state at all observed wavelengths, showing only moderate variability from radio to X-rays. A low degree of polarization of less than 10\\% was...

  12. A Three-Year Multi-Wavelength Study of the Very High Energy Gamma-ray Blazar 1ES 0229+200

    CERN Document Server

    Aliu, E; Arlen, T; Aune, T; Behera, B; Beilicke, M; Benbow, W; Berger, K; Bird, R; Bouvier, A; Buckley, J H; Bugaev, V; Byrum, K; Cerruti, M; Chen, X; Ciupik, L; Connolly, M P; Cui, W; Duke, C; Dumm, J; Errando, M; Falcone, A; Federici, S; Feng, Q; Finley, J P; Fleischhack, H; Fortin, P; Fortson, L; Furniss, A; Galante, N; Gillanders, G H; Griffin, S; Griffiths, S T; Grube, J; Gyuk, G; Hanna, D; Holder, J; Hughes, G; Humensky, T B; Johnson, C A; Kaaret, P; Kertzman, M; Khassen, Y; Kieda, D; Krawczynski, H; Krennrich, F; Lang, M J; Madhavan, A S; Maier, G; Majumdar, P; McArthur, S; McCann, A; Meagher, K; Millis, J; Moriarty, P; Mukherjee, R; Nieto, D; de Bhroithe, A O'Faolain; Ong, R A; Otte, A N; Park, N; Perkins, J S; Pohl, M; Popkow, A; Prokoph, H; Quinn, J; Ragan, K; Reyes, L C; Reynolds, P T; Richards, G T; Roache, E; Sembroski, G H; Smith, A W; Staszak, D; Telezhinsky, I; Theiling, M; Varlotta, A; Vassiliev, V V; Vincent, S; Wakely, S P; Weekes, T C; Weinstein, A; Welsing, R; Williams, D A; Zajczyk, A; Zitzer, B

    2013-01-01

    The high-frequency-peaked BL Lacertae object 1ES 0229+200 is a relatively distant (z = 0.1396), hard-spectrum (Gamma ~ 2.5), very-high-energy-emitting (E > 100 GeV) gamma-ray blazar. Very-high-energy measurements of this active galactic nucleus have been used to place constraints on the intensity of the extragalactic background light and the intergalactic magnetic field. A multi-wavelength study of this object centered around very-high-energy observations by VERITAS is presented. This study obtained, over a period of three years, an 11.7 standard deviation detection and an average integral flux F(E>300 GeV) = (23.3 +- 2.8_stat +- 5.8_sys) x 10^-9 photons m^-2 s^-1, or 1.7% of the Crab Nebula's flux (assuming the Crab Nebula spectrum measured by H.E.S.S). Supporting observations from Swift and RXTE are analyzed. The Swift observations are combined with previously published Fermi observations and the very-high-energy measurements to produce an overall spectral energy distribution which is then modeled assuming ...

  13. Mrk 421, Mrk 501, and 1ES 1426+428 at 100 GeV with the CELESTE Cherenkov Telescope

    CERN Document Server

    Smith, D A; Britto, R; Bruel, P; Gordo, J B; Dumora, D; Durand, E; Eschstruth, P; Espigat, P; Holder, J; Jacholkowska, A; Lavalle, J; Le Gallou, R; Lott, B; Manseri, H; Munz, F; Nuss, E; Piron, Frédéric; Reposeur, T; Sako, T

    2006-01-01

    We have measured the gamma-ray fluxes of the blazars Mrk 421 and Mrk 501 in the energy range between 50 and 350 GeV (1.2 to 8.3 x 10^25 Hz). The detector, called CELESTE, used first 40, then 53 heliostats of the former solar facility "Themis" in the French Pyrenees to collect Cherenkov light generated in atmospheric particle cascades. The signal from Mrk 421 is often strong. We compare its flux with previously published multi-wavelength studies and infer that we are straddling the high energy peak of the spectral energy distribution. The signal from Mrk 501 in 2000 was weak (3.4 sigma). We obtain an upper limit on the flux from 1ES 1426+428 of less than half that of the Crab flux near 100 GeV. The data analysis and understanding of systematic biases have improved compared to previous work, increasing the detector's sensitivity.

  14. Optical polarimetry and photometry of X-ray selected BL Lacertae objects

    Science.gov (United States)

    Jannuzi, Buell T.; Smith, Paul S.; Elston, Richard

    1993-01-01

    We present the data from 3 years of monitoring the optical polarization and apparent brightness of 37 X-ray-selected BL Lacertae objects. The monitored objects include a complete sample drawn from the Einstein Extended Medium Sensitivity Survey. We confirm the BL Lac identifications for 15 of these 22 objects. We include descriptions of the objects and samples in our monitoring program and of the existing complete samples of BL Lac objects, highly polarized quasars, optically violent variable quasars, and blazars.

  15. Lac Courte Oreilles Hydro Dam Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, Jason [Lac Courte Oreilles, Hayward, WI (United States); Meyers, Amy [Kiser Hydro, LLC, Norway, MI (United States)

    2014-12-31

    The main objective of this project was to investigate upgrading the existing hydro power generating system at the Winter Dam. The tribe would like to produce more energy and receive a fair market power purchase agreement so the dam is no longer a drain on our budget but a contributor to our economy. We contracted Kiser Hydro, LLC Engineering for this project and received an engineering report that includes options for producing more energy with cost effective upgrades to the existing turbines. Included in this project was a negotiation of energy price sales negotiations.

  16. Characterisation and discrimination of various types of lac resin using gas chromatography mass spectrometry techniques with quaternary ammonium reagents.

    Science.gov (United States)

    Sutherland, K; del Río, J C

    2014-04-18

    A variety of lac resin samples obtained from artists' suppliers, industrial manufacturers, and museum collections were analysed using gas chromatography mass spectrometry (GCMS) and reactive pyrolysis GCMS with quaternary ammonium reagents. These techniques allowed a detailed chemical characterisation of microgram-sized samples, based on the detection and identification of derivatives of the hydroxy aliphatic and cyclic (sesquiterpene) acids that compose the resin. Differences in composition could be related to the nature of the resin, e.g. wax-containing (unrefined), bleached, or aged samples. Furthermore, differences in the relative abundances of aliphatic hydroxyacids appear to be associated with the biological source of the resin. The diagnostic value of newly characterised lac components, including 8-hydroxyacids, is discussed here for the first time. Identification of derivatised components was aided by AMDIS deconvolution software, and discrimination of samples was enhanced by statistical evaluation of data using principal component analysis. The robustness of the analyses, together with the minimal sample size required, make these very powerful approaches for the characterisation of lac resin in museum objects. The value of such analyses for enhancing the understanding of museum collections is illustrated by two case studies of objects in the collection of the Philadelphia Museum of Art: a restorer's varnish on a painting by Luca Signorelli, and a pictorial inlay in an early nineteenth-century High Chest by George Dyer. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Wind Resource Assessment Report: Mille Lacs Indian Reservation, Minnesota

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, A. C.

    2013-12-01

    The U.S. Environmental Protection Agency (EPA) launched the RE-Powering America's Land initiative to encourage development of renewable energy on potentially contaminated land and mine sites. EPA collaborated with the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL) and the Mille Lacs Band of Chippewa Indians to evaluate the wind resource and examine the feasibility of a wind project at a contaminated site located on the Mille Lacs Indian Reservation in Minnesota. The wind monitoring effort involved the installation of a 60-m met tower and the collection of 18 months of wind data at multiple heights above the ground. This report focuses on the wind resource assessment, the estimated energy production of wind turbines, and an assessment of the economic feasibility of a potential wind project sited this site.

  18. First photometric study of W UMa binary star LU Lac

    Science.gov (United States)

    Liao, W.-P.; Qian, S.-B.; Zhao, E.-G.; Jiang, L.-Q.

    2014-08-01

    LU Lac is a neglected W UMa binary star in photometric investigations. In this paper, we present BVRI CCD photometric light curves obtained on one night in 2012. The first photometric solutions of this system are computed by using the Wilson-Devinney code. It is shown that LU Lac is a marginal contact W-type system with a degree of contact factor of f=8.9%, a mass ratio of q=2.085 and a high inclination of i=82°.20. From the first analyses of orbital period changes, we found the period variation of the system includes an oscillation (A3=0.0125 days and T3=51.92 years). The cyclic change may be attributed to the light-travel time effect through the presence of a third body.

  19. Evolution and Biophysics of the Escherichia coli lac Operon

    Science.gov (United States)

    Ray, J. Christian; Igoshin, Oleg; Quan, Selwyn; Monds, Russell; Cooper, Tim; Balázsi, Gábor

    2011-03-01

    To understand, predict, and control the evolution of living organisms, we consider biophysical effects and molecular network architectures. The lactose utilization system of E. coli is among the most well-studied molecular networks in biology, making it an ideal candidate for such studies. Simulations show how the genetic architecture of the wild-type operon attenuates large metabolic intermediate fluctuations that are predicted to occur in an equivalent system with the component genes on separate operons. Quantification of gene expression in the lac operon evolved in growth conditions containing constant lactose, alternating with glucose, or constant glucose, shows characteristic gene expression patterns depending on conditions. We are simulating these conditions to show context-dependent biophysical sources and costs of different lac operon architectures.

  20. Challenge of lightning detection with LAC on board Akatsuki spacecraft

    Science.gov (United States)

    Takahashi, Yukihiro; Sato, Mitsutero; Imai, Masataka; Yair, Yoav; Fischer, Georg; Aplin, Karen

    2016-04-01

    Even after extensive investigations with spacecraft and ground-based observations, there is still no consensus on the existence of lightning in Venus. It has been reported that the magnetometer on board Venus Express detected whistler mode waves whose source could be lightning discharge occurring well below the spacecraft. On the other hand, with an infrared sensor, VIRTIS of Venus Express, does not show the positive indication of lightning flashes. In order to identify the optical flashes caused by electrical discharge in the atmosphere of Venus, at least, with an optical intensity of 1/10 of the average lightning in the Earth, we built a high-speed optical detector, LAC (Lightning and Airglow Camera), on board Akatsuki spacecraft. The unique performance of the LAC compared to other instruments is the high-speed sampling rate at 32 us interval for all 32 pixels, enabling us to distinguish the optical lightning flash from other pulsing noises. Though, unfortunately, the first attempt of the insertion of Akatsuki into the orbit around Venus failed in December 2010, the second one carried out in December 7 in 2015 was quite successful. We checked out the condition of the LAC on January 5, 2016, and it is healthy as in 2010. Due to some elongated orbit than that planned originally, we have umbra for ~30 min to observe the lightning flash in the night side of Venus every ~10 days, starting on April 2016. Here we would report the instrumental status of LAC and the preliminary results of the first attempt to observe optical lightning emissions.

  1. L'aménagement piscicole des lacs subalpins

    Directory of Open Access Journals (Sweden)

    VIVIER P.

    1964-04-01

    Le rendement financier annuel varie non seulement avec l'abondance des captures mais aussi avec la qualité du poisson péché. Aussi dans le Lac Léman le prix moyen de 10 kg de poisson péchés a augmenté de 4 F, de 1922 à 1961, grâce à une plus grande abondance relative des Corégones.

  2. Period of Light Variability in BL Lac ON 231

    Indian Academy of Sciences (India)

    Xu Yun Bing; Zhang Hao Jing; Zhang Xiong; Mao Wei Ming; Dong Fu Tong

    2011-03-01

    In this paper, the authors have compiled the data of about 100 years in B-band of the BL Lac ON 231 and used this database to analyze periodicity signals in the optical light curve. Two different methods were applied: the wavelet analysis and the Discrete Correlation Function (DCF) method. We revealed the existence of periods of 13.5 years in the source variability.

  3. Du Lac de Geneve au Lac Baikal: deux metropoles en construction

    Directory of Open Access Journals (Sweden)

    Guy Mettan

    2006-08-01

    Full Text Available En apparence, Geneve et Irkutsk n'ont rien en commun. A part une amitie reciproque et la proximite d'un lac, il est difficile de trouver des points communs entre la Suisse francophone, dont Geneve est la ville le plus importante, et la Siberie centrale, dont Irkutsk, est la capitale. Et pourtant les deux regions, malgre les differences de taille, de densite de la population, de climat, d'economie et de traditions culturelles, sont confrontees au meme probleme: elles sont trop petites et trop limitees pour assurer, avec leurs seuls moyens, leur avenir et elles doivent imperativement s'unir a des villes voisines pour renforcer leur statut de metropole regionale et s'imposer face aux regions et aux pays concurrents.C'est ainsi qu'Irkutsk projette de s'unir aux villes voisines d'Angarsk et de Chelekhov pour constituer une megapole au c?ur de la Siberie, tandis qu'a Geneve le debat fait rage pour trouver des solutions a l'exiguite geographique et a l'insuffisance des moyens face aux grandes regions metropolitaines de France, d'Italie et d'Allemagne.Ce debat est propre a toute la Suisse. Malgre sa petitesse, la Suisse est divisee en 26 cantons. Ces unites administratives sont jugees trop couteuses, trop petites, trop lourdes et trop compliquees pour assurer l'avenir economique et meme politique du pays. De nombreux groupes de reflexion proposent donc de reduire ce nombre a 3, 5 ou 10 grandes provinces selon les cas. En Suisse, romande, il y a dix ans, des mouvements politiques ont meme lance l'idee de fusionner les cantons de Vaud (dont Lausanne est la capitale et de Geneve. Mais l'echec a ete fracassant : le peuple des deux cantons a refuse cette option a 80% des voix. On cherche donc d'autres solutions.Les discussions s'orientent desormais autour de la constitution d'une grande metropole lemanique qui regrouperait les deux grandes villes de Geneve et Lausanne et les villes plus petites de Montreux, Vevey, Nyon ainsi que la ville francaise d

  4. METHODICAL APPROACHES TO THE CREATION MOOC (EXPERIENCE LAC

    Directory of Open Access Journals (Sweden)

    Larysa Nozdrina

    2016-03-01

    Full Text Available The article presents a number of problems, determining the current state of development of the domestic market of massive open online courses (MOOC. Considering the aim of the research, there is described national experience in this area, proposed and substantiated a number of the criteria and methodological approaches to the implementation of MOOC in higher education. The development of MOOC in the Lviv Academy of Commerce (LAC is reviewed as example. The main factors which determine the success of this educational innovation in the domestic market and are put under the research are software platforms, multimedia software for creating video lectures, course structure and support the learning process. The results of study which have been analyzed in this course can have a positive impact on the functioning of the market MOOC in Ukrainian universities. The article focuses on finding the ways of improving the process of developing and implementing MOOC in higher education in the example of LAC where Web-center on the MOODLE platform is used for e-learning. Further research should focus on the development of institutional mechanisms to ensure the effective design, implementation and operation of the MOOC in the universities in Ukraine. Particular attention during learning in massive open online course should be aimed at improving the educational process and to strengthen student's motivation in MOOC. Experience of MOOC's development in LAC can be useful at creating similar courses at other institutions of higher education in the different platforms, both MOODLE, and on the others

  5. Photometric Redshifts of High-z BL Lacs from 3FGL Catalog

    Science.gov (United States)

    Kaur, A.; Rau, Arne; Ajello, Marco; Paliya, Vaidehi; Hartmann, Dieter; Greiner, Jochen; Bolmer, Jan; Schady, Patricia

    2017-08-01

    Determining redshifts for BL Lacertae (BL Lac) objects using the traditional spectroscopic method is challenging due to the absence of strong emission lines in their optical spectra. We employ the photometric dropout technique to determine redshifts for this class of blazars using the combined 13 broad-band filters from Swift-UVOT and the multi-channel imager GROND at the MPG 2.2 m telescope at ESO's La Silla Observatory. The wavelength range covered by these 13 filters extends from far ultraviolet to the near-Infrared. We report results on 40 new Fermi detected BL Lacs with the photometric redshifts determinations for 5 sources, with 3FGL J1918.2-4110 being the most distance in our sample at z=2.16. Reliable upper limits are provided for 20 sources in this sample. Using the highest energy photons for these Fermi-LAT sources, we evaluate the consistency with the Gamma-ray horizon due to the extragalactic background light.

  6. Parsec-scale Magnetic-Field Structures in HEAO-1 BL Lacs

    CERN Document Server

    Kharb, P; Shastri, P

    2007-01-01

    We present very long baseline interferometry polarization images of an X-ray selected sample of BL Lacertae objects belonging to the first High Energy Astronomy Observatory (HEAO-1) and the ROSAT-Green Bank (RGB) surveys. These are primarily high-energy-peaked BL Lacs (HBLs) and exhibit core-jet radio morphologies on pc-scales. They show moderately polarized jet components, similar to those of low-energy-peaked BL Lacs (LBLs). The fractional polarization in the unresolved cores of the HBLs is, on average, lower than in the LBLs, while the fractional polarizations in the pc-scale jets of HBLs and LBLs are comparable. However a difference is observed in the orientation of the inferred jet magnetic fields -- while LBL jets are well-known to preferentially exhibit transverse magnetic fields, the HBL jets tend to display longitudinal magnetic fields. Although a `spine-sheath' jet velocity structure, along with larger viewing angles for HBLs could produce the observed magnetic field configuration, differences in ot...

  7. New High-z Fermi BL Lacs with the Photometric Dropout Technique

    Science.gov (United States)

    Kaur, A.; Rau, A.; Ajello, M.; Greiner, J.; Hartmann, D. H.; Paliya, V. S.; Domínguez, A.; Bolmer, J.; Schady, P.

    2017-01-01

    Determining redshifts for BL Lacertae (BL Lac) objects using the traditional spectroscopic method is challenging due to the absence of strong emission lines in their optical spectra. We employ the photometric dropout technique to determine redshifts for this class of blazars using the combined 13 broadband filters from Swift-UVOT and the multi-channel imager GROND at the MPG 2.2 m telescope at ESO's La Silla Observatory. The wavelength range covered by these 13 filters extends from far-ultraviolet to the near-infrared. We report results on 40 new Fermi-detected BL Lacs with the photometric redshift determinations for five sources, with 3FGL J1918.2–4110 being the most distant in our sample at z = 2.16. Reliable upper limits are provided for 20 sources in this sample. Using the highest energy photons for these Fermi-LAT sources, we evaluate the consistency with the gamma-ray horizon due to the extragalactic background light.

  8. New High-z Fermi BL Lacs with the Photometric Dropout Technique

    CERN Document Server

    Kaur, A; Ajello, M; Greiner, J; Hartmann, D H; Paliya, V S; Dominguez, A; Bolmer, J; Schady, P

    2016-01-01

    Determining redshifts for BL Lacertae (BL Lac) objects using the traditional spectroscopic method is challenging due to the absence of strong emission lines in their optical spectra. We employ the photometric dropout technique to determine redshifts for this class of blazars using the combined 13 broad-band filters from Swift-UVOT and the multi-channel imager GROND at the MPG 2.2 m telescope at ESO's La Silla Observatory. The wavelength range covered by these 13 filters extends from far ultraviolet to the near-Infrared. We report results on 40 new Fermi detected BL Lacs with the photometric redshifts determinations for 5 sources, with 3FGL J1918.2-4110 being the most distant in our sample at z=2.16. Reliable upper limits are provided for 20 sources in this sample. Using the highest energy photons for these Fermi-LAT sources, we evaluate the consistency with the Gamma-ray horizon due to the extragalactic background light.

  9. Purification and characterization of two phospho-β-galactosidases, LacG1 and LacG2, from Lactobacillus gasseri ATCC33323T

    NARCIS (Netherlands)

    Honda, Hiroyuki; Nagaoka, Seiji; Kawai, Yasushi; Kemperman, Robèr; Kok, Jan; Yamazaki, Yukiko; Tateno, Yoshio; Kitazawa, Haruki; Saito, Tadao

    2012-01-01

    Lactobacillus gasseri ATCC33323T expresses four enzymes showing phospho-β-galactosidase activity (LacG1, LacG2, Pbg1 and Pbg2). We previously reported the purification and characterization of two phospho-β-galactosidases (Pbg1 and Pbg2) from Lactobacillus gasseri JCM1031 cultured in lactose medium.

  10. Discovery of very high energy gamma-ray emission from the blazar 1ES 0033+595 by the MAGIC telescopes

    CERN Document Server

    Aleksić, J; Antonelli, L A; Antoranz, P; Babic, A; Bangale, P; de Almeida, U Barres; Barrio, J A; González, J Becerra; Bednarek, W; Berger, K; Bernardini, E; Biland, A; Blanch, O; Bonnefoy, S; Bonnoli, G; Borracci, F; Bretz, T; Carmona, E; Carosi, A; Fidalgo, D Carreto; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Caneva, G; De Lotto, B; Mendez, C Delgado; Doert, M; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Einecke, S; Eisenacher, D; Elsaesser, D; Farina, E; Ferenc, D; Fonseca, M V; Font, L; Frantzen, K; Fruck, C; López, R J García; Garczarczyk, M; Terrats, D Garrido; Gaug, M; Godinović, N; Muñoz, A González; Gozzini, S R; Hadasch, D; Hayashida, M; Herrera, J; Herrero, A; Hildebrand, D; Hose, J; Hrupec, D; Idec, W; Kadenius, V; Kellermann, H; Kodani, K; Konno, Y; Krause, J; Kubo, H; Kushida, J; La Barbera, A; Lelas, D; Lewandowska, N; Lindfors, E; Lombardi, S; López, M; López-Coto, R; López-Oramas, A; Lorenz, E; Lozano, I; Makariev, M; Mallot, K; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martínez, M; Mazin, D; Menzel, U; Meucci, M; Miranda, J M; Mirzoyan, R; Moralejo, A; Munar-Adrover, P; Nakajima, D; Niedzwiecki, A; Nilsson, K; Nishijima, K; Noda, K; Nowak, N; Orito, R; Overkemping, A; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, J M; Paredes-Fortuny, X; Partini, S; Persic, M; Prada, F; Moroni, P G Prada; Prandini, E; Preziuso, S; Puljak, I; Reinthal, R; Rhode, W; Ribó, M; Rico, J; Garcia, J Rodriguez; Rügamer, S; Saggion, A; Saito, T; Saito, K; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Shore, S N; Sillanpää, A; Sitarek, J; Snidaric, I; Sobczynska, D; Spanier, F; Stamatescu, V; Stamerra, A; Steinbring, T; Storz, J; Sun, S; Surić, T; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzić, T; Tescaro, D; Teshima, M; Thaele, J; Tibolla, O; Torres, D F; Toyama, T; Treves, A; Uellenbeck, M; Vogler, P; Wagner, R M; Zandanel, F; Zanin, R; Tronconi, V; Buson, S

    2014-01-01

    The number of known very high energy (VHE) blazars is $\\sim\\,50$, which is very small in comparison to the number of blazars detected in other frequencies. This situation is a handicap for population studies of blazars, which emit about half of their luminosity in the $\\gamma$-ray domain. Moreover, VHE blazars, if distant, allow for the study of the environment that the high-energy $\\gamma$-rays traverse in their path towards the Earth, like the extragalactic background light (EBL) and the intergalactic magnetic field (IGMF), and hence they have a special interest for the astrophysics community. We present the first VHE detection of 1ES\\,0033+595 with a statistical significance of 5.5\\,$\\sigma$. The VHE emission of this object is constant throughout the MAGIC observations (2009 August and October), and can be parameterized with a power law with an integral flux above 150 GeV of $(7.1\\pm1.3)\\times 10^{-12} {\\mathrm{ph\\,cm^{-2}\\,s^{-1}}}$ and a photon index of ($3.8\\pm0.7$). We model its spectral energy distrib...

  11. Chemo-enzymatic modification of poly-N-acetyllactosamine (LacNAc oligomers and N,N-diacetyllactosamine (LacDiNAc based on galactose oxidase treatment

    Directory of Open Access Journals (Sweden)

    Christiane E. Kupper

    2012-05-01

    Full Text Available The importance of glycans in biological systems is highlighted by their various functions in physiological and pathological processes. Many glycan epitopes on glycoproteins and glycolipids are based on N-acetyllactosamine units (LacNAc; Galβ1,4GlcNAc and often present on extended poly-LacNAc glycans ([Galβ1,4GlcNAc]n. Poly-LacNAc itself has been identified as a binding motif of galectins, an important class of lectins with functions in immune response and tumorigenesis. Therefore, the synthesis of natural and modified poly-LacNAc glycans is of specific interest for binding studies with galectins as well as for studies of their possible therapeutic applications. We present the oxidation by galactose oxidase and subsequent chemical or enzymatic modification of terminal galactose and N-acetylgalactosamine residues of poly-N-acetyllactosamine (poly-LacNAc oligomers and N,N-diacetyllactosamine (LacDiNAc by galactose oxidase. Product formation starting from different poly-LacNAc oligomers was characterised and optimised regarding formation of the C6-aldo product. Further modification of the aldehyde containing glycans, either by chemical conversion or enzymatic elongation, was established. Base-catalysed β-elimination, coupling of biotin–hydrazide with subsequent reduction to the corresponding hydrazine linkage, and coupling by reductive amination to an amino-functionalised poly-LacNAc oligomer were performed and the products characterised by LC–MS and NMR analysis. Remarkably, elongation of terminally oxidised poly-LacNAc glycans by β3GlcNAc- and β4Gal-transferase was also successful. In this way, a set of novel, modified poly-LacNAc oligomers containing terminally and/or internally modified galactose residues were obtained, which can be used for binding studies and various other applications.

  12. Simultaneous multiwavelength observations of the blazar 1ES1959+650 at a low TeV flux

    CERN Document Server

    Tagliaferri, G; Ghisellini, G; Maraschi, L; Tosti, G; Albert, J; Aliu, E; Anderhub, H; Antoranz, P; Baixeras, C

    2008-01-01

    We present the results from a multiwavelength campaign on the TeV blazar 1ES 1959+650, performed in May, 2006. Data from the optical, UV, soft- and hard-X-ray and very high energy (VHE) gamma-ray (E > 100 GeV) bands were obtained with the SUZAKU and SWIFT satellites, with the MAGIC telescope and other ground based facilities. The source spectral energy distribution (SED), derived from SUZAKU and MAGIC observations at the end of May 2006, shows the usual double hump shape, with the synchrotron peak at a higher flux level than the Compton peak. With respect to historical values, during our campaign the source exhibited a relatively high state in X-rays and optical, while in the VHE band it was at one of the lowest level so far recorded. We also monitored the source for flux-spectral variability on a time window of 10 days in the optical-UV and X-ray bands and 7 days in the VHE band. The source varies more in the X-ray, than in the optical band, with the 2-10 keV X-ray flux varying by a factor of ~2. The synchro...

  13. Probing BL Lac and Cluster Evolution via a Wide-angle, Deep X-ray Selected Sample

    Science.gov (United States)

    Perlman, E.; Jones, L.; White, N.; Angelini, L.; Giommi, P.; McHardy, I.; Wegner, G.

    1994-12-01

    The WARPS survey (Wide-Angle ROSAT Pointed Survey) has been constructed from the archive of all public ROSAT PSPC observations, and is a subset of the WGACAT catalog. WARPS will include a complete sample of >= 100 BL Lacs at F_x >= 10(-13) erg s(-1) cm(-2) . A second selection technique will identify ~ 100 clusters at 0.15 = 0.304 +/- 0.062 for XBLs but = 0.60 +/- 0.05 for RBLs. Models of the X-ray luminosity function (XLF) are also poorly constrained. WARPS will allow us to compute an accurate XLF, decreasing the error bars above by over a factor of two. We will also test for low-luminosity BL Lacs, whose non-thermal nuclear sources are dim compared to the host galaxy. Browne and Marcha (1993) claim the EMSS missed most of these objects and is incomplete. If their predictions are correct, 20-40% of the BL Lacs we find will fall in this category, enabling us to probe the evolution and internal workings of BL Lacs at lower luminosities than ever before. By removing likely QSOs before optical spectroscopy, WARPS requires only modest amounts of telescope time. It will extend measurement of the cluster XLF both to higher redshifts (z>0.5) and lower luminosities (LX<1x10(44) erg s(-1) ) than previous measurements, confirming or rejecting the 3sigma detection of negative evolution found in the EMSS, and constraining Cold Dark Matter cosmologies. Faint NELGs are a recently discovered major contributor to the X-ray background. They are a mixture of Sy2s, starbursts and galaxies of unknown type. Detailed classification and evolution of their XLF will be determined for the first time.

  14. Aspartoacylase-lacZ knockin mice: an engineered model of Canavan disease.

    Directory of Open Access Journals (Sweden)

    Nadine Mersmann

    Full Text Available Canavan Disease (CD is a recessive leukodystrophy caused by loss of function mutations in the gene encoding aspartoacylase (ASPA, an oligodendrocyte-enriched enzyme that hydrolyses N-acetylaspartate (NAA to acetate and aspartate. The neurological phenotypes of different rodent models of CD vary considerably. Here we report on a novel targeted aspa mouse mutant expressing the bacterial β-Galactosidase (lacZ gene under the control of the aspa regulatory elements. X-Gal staining in known ASPA expression domains confirms the integrity of the modified locus in heterozygous aspa lacZ-knockin (aspa(lacZ/+ mice. In addition, abundant ASPA expression was detected in Schwann cells. Homozygous (aspa(lacZ/lacZ mutants are ASPA-deficient, show CD-like histopathology and moderate neurological impairment with behavioural deficits that are more pronounced in aspa(lacZ/lacZ males than females. Non-invasive ultrahigh field proton magnetic resonance spectroscopy revealed increased levels of NAA, myo-inositol and taurine in the aspa(lacZ/lacZ brain. Spongy degeneration was prominent in hippocampus, thalamus, brain stem, and cerebellum, whereas white matter of optic nerve and corpus callosum was spared. Intracellular vacuolisation in astrocytes coincides with axonal swellings in cerebellum and brain stem of aspa(lacZ/lacZ mutants indicating that astroglia may act as an osmolyte buffer in the aspa-deficient CNS. In summary, the aspa(lacZ mouse is an accurate model of CD and an important tool to identify novel aspects of its complex pathology.

  15. lac Up-promoter mutants with increased homology to the consensus promoter sequence.

    OpenAIRE

    Mandecki, W; Goldman, R A; Powell, B S; Caruthers, M H

    1985-01-01

    Four lac promoter mutants were constructed. The mutations increased the homology between the lac promoter and the consensus promoter sequences by introducing the consensus -10 and -35 regions and the consensus spacing of 17 residues between these two regions. The promoter mutants were cloned into a pBR322-derivatized vector upstream from the lacZ gene, and levels of beta-galactosidase were an indication of promoter activity. All mutants exhibited higher activity than did the wild-type promoter.

  16. The Cosmological Evolution of BL Lacertae Objects

    CERN Document Server

    Giommi, P; Perri, M; Padovani, P

    2000-01-01

    We review the main results from several radio, X-ray and multi-frequency surveys on the topic of cosmological evolution of BL Lacertae objects. Updated findings on BL Lac evolution following the recent identification of many sources in the ``Sedentary Multi-Frequency survey'' are also discussed. By means of extensive Monte Carlo simulations we test some possible explanations for the peculiar cosmological evolution of BL Lacs. We find that a dependence of the relativistic Doppler factor on radio luminosity (as expected within the beaming scenario) may induce low values of V/V_max and that both edge effects at the low luminosity end of the BL Lacs radio luminosity function, and incompleteness at faint optical magnitudes may be the cause of the low V/V_max found for extreme HBL sources in X-ray selected samples.

  17. Mapping DNA-Lac repressor interaction with ultra-fast optical tweezers

    Science.gov (United States)

    Monico, Carina; Tempestini, Alessia; Vanzi, Francesco; Pavone, Francesco S.; Capitanio, Marco

    2015-03-01

    The lac operon is a well-known example of gene expression regulation, based on the specific interaction of Lac repressor protein (LacI) with its target DNA sequence (operator). We recently developed an ultrafast force-clamp laser trap technique capable of probing molecular interactions with sub-ms temporal resolution, under controlled pN-range forces. With this technique, we tested the interaction of LacI with different DNA constructs. Based on position along the DNA sequence, the observed interactions can be interpreted as specific binding to operator sequences and transient interactions with nonspecific sequences.

  18. LONG-TERM OPTICAL POLARIZATION VARIABILITY OF THE TeV BLAZAR 1ES 1959+650

    Energy Technology Data Exchange (ETDEWEB)

    Sorcia, Marco; Benitez, Erika; Cabrera, Jose I. [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Apdo. 70-264, Mexico D.F. 04510 (Mexico); Hiriart, David; Lopez, Jose M. [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Apdo. 810, Ensenada, B.C. 22800 (Mexico); Mujica, Raul [Instituto Nacional de Astrofisica, Optica y Electronica, Apdo. Postal 51 y 216, 72000 Tonantzintla, Puebla (Mexico); Heidt, Jochen; Mommert, Michael [ZAH, Landessternwarte Heidelberg, Koenigstuhl, D-69117 Heidelberg (Germany); Agudo, Ivan [Instituto Nacional de Astrofisica de Andalucia, CSIC, Apartado 3004, E-18080 Granada (Spain); Nilsson, Kari, E-mail: msorcia@astro.unam.mx [Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Vaeisaelaentie 20, FI-21500 Piikkioe (Finland)

    2013-06-01

    A detailed analysis of the optical polarimetric variability of the TeV blazar 1ES 1959+650 from 2007 October 18 to 2011 May 5 is presented. The source showed maximum and minimum brightness states in the R band of 14.08 {+-} 0.03 mag and 15.20 {+-} 0.03 mag, respectively, with a maximum variation of 1.12 mag, and a maximum polarization degree of P = (12.2 {+-} 0.7)%, with a maximum variation of 10.7%. From 2009 August to November, a correlation between the optical R-band flux and the degree of linear polarization was found with a correlation coefficient r {sub pol} = 0.984 {+-} 0.025. The source presented a preferential position angle of optical polarization of {approx}153 Degree-Sign , with variations of 10 Degree-Sign -50 Degree-Sign , which is in agreement with the projected position angle of the parsec-scale jet found at 43 GHz. From the Stokes parameters we infer the existence of two optically thin synchrotron components that contribute to the polarized flux. One of them is stable with a constant polarization degree of 4%. Assuming a stationary shock for the variable component, we estimated some parameters associated with the physics of the relativistic jet: the magnetic field, B {approx} 0.06 G, the Doppler factor, {delta}{sub 0} {approx} 23, the viewing angle, {Phi} {approx} 2. Degree-Sign 4, and the size of the emission region r{sub b} {approx} 5.6 Multiplication-Sign 10{sup 17} cm. Our study is consistent with the spine-sheath model of explaining the polarimetric variability displayed by this source during our monitoring.

  19. Long-term Optical Polarization Variability of the TeV Blazar 1ES 1959+650

    Science.gov (United States)

    Sorcia, Marco; Benítez, Erika; Hiriart, David; López, José M.; Cabrera, José I.; Mújica, Raúl; Heidt, Jochen; Agudo, Iván; Nilsson, Kari; Mommert, Michael

    2013-06-01

    A detailed analysis of the optical polarimetric variability of the TeV blazar 1ES 1959+650 from 2007 October 18 to 2011 May 5 is presented. The source showed maximum and minimum brightness states in the R band of 14.08 ± 0.03 mag and 15.20 ± 0.03 mag, respectively, with a maximum variation of 1.12 mag, and a maximum polarization degree of P = (12.2 ± 0.7)%, with a maximum variation of 10.7%. From 2009 August to November, a correlation between the optical R-band flux and the degree of linear polarization was found with a correlation coefficient r pol = 0.984 ± 0.025. The source presented a preferential position angle of optical polarization of ~153°, with variations of 10°-50°, which is in agreement with the projected position angle of the parsec-scale jet found at 43 GHz. From the Stokes parameters we infer the existence of two optically thin synchrotron components that contribute to the polarized flux. One of them is stable with a constant polarization degree of 4%. Assuming a stationary shock for the variable component, we estimated some parameters associated with the physics of the relativistic jet: the magnetic field, B ~ 0.06 G, the Doppler factor, δ0 ~ 23, the viewing angle, Φ ~ 2.°4, and the size of the emission region rb ~ 5.6 × 1017 cm. Our study is consistent with the spine-sheath model of explaining the polarimetric variability displayed by this source during our monitoring.

  20. Ultraviolet polarimetry and spectroscopy of the BL Lacertae object PKS 2155-304

    Science.gov (United States)

    Allen, Richard G.; Smith, Paul S.; Angel, J. R. P.; Miller, Bryan W.; Anderson, Scott F.; Margon, Bruce

    1993-01-01

    HST and Faint Object Spectrograph spectropolarimetry is presented for the BL Lac object PKS 2155-304; attention is given to the wavelength dependence of the UV linear polarization in a BL Lac object. The UV polarimetry yields evidence that the UV polarized flux is generated by the synchrotron mechanism responsible for optical polarization. Both the UV and optical emission are produced in the same region of the source.

  1. Exploring the magnetic field configuration in BL Lac using GMVA

    CERN Document Server

    Rani, B; Hodgson, J; Koyama, S; Zensus, J A; Fuhrmann, L; Marscher, A P; Jorstad, S G

    2016-01-01

    The high radio frequency polarization imaging of non-thermal emission from active galactic nuclei (AGN) is a direct way to probe the magnetic field strength and structure in the immediate vicinity of supermassive black holes (SMBHs) and is crucial in testing the jet-launching scenario. To explore the the magnetic field configuration at the base of jets in blazars, we took advantage of the full polarization capabilities of the Global Millimeter VLBI Array (GMVA). With an angular resolution of $\\sim$50 micro-arcseconds ($\\mu$as) at 86 GHz, one could resolve scales up to $\\sim$450 gravitational radii (for a 10$^9$ solar mass black hole at a redshift of 0.1). We present here the preliminary results of our study on the blazar BL~Lac. Our results suggest that on sub-mas scales the core and the central jet of BL Lac are significantly polarized with two distinct regions of polarized intensity. We also noted a great morphological similarity between the 7mm/3mm VLBI images at very similar angular resolution.

  2. Light Curve and Orbital Period Analysis of VX Lac

    Science.gov (United States)

    Yılmaz, M.; Nelson, R. H.; Şenavcı, H. V.; İzci, D.; Özavcı, İ.; Gümüş, D.

    2017-04-01

    In this study, we performed simultaneously light curve and radial velocity, and also period analyses of the eclipsing binary system VX Lac. Four color (BVRI) light curves of the system were analysed using the W-D code. The results imply that VX Lac is a classic Algol-type binary with a mass ratio of q=0.27, of which the less massive secondary component fills its Roche lobe. The orbital period behaviour of the system was analysed by assuming the light time effect (LITE) from a third body. The O-C analysis yielded a mass transfer rate of dM/dt=1.86×10-8Mȯyr-1 and the minimal mass of the third body to be M3=0.31Mȯ. The residuals from mass transfer and the third body were also analysed because another cyclic variation is seen in O-C diagram. This periodic variation was examined under the hypotheses of stellar magnetic activity and fourth body.

  3. Decadal to millennial scale geomagnetic field variations in the Levantine archaeointensity curve (LAC): methodology and applications

    Science.gov (United States)

    Shaar, Ron; Tauxe, Lisa; Ron, Hagai; Agnon, Amotz; Ben-Yosef, Erez; Finkelstein, Israel; Zuckerman, Sharon; Levy, Thomas E.

    2014-05-01

    Recovering the absolute intensity of the geomagnetic field on historical and archaeological timescale (archaeointensity) in a sufficient resolution is a fundamental effort in the paleomagnetic research. However, it is a complicated task hampered by some serious methodological difficulties. First, paleointensity experiments should be carefully designed using sufficient number of specimens, and accurate correction for remanence anisotropy, cooling rate effects, and non-linear TRM (NLT). Second, the basic assumption of the paleointensity method - that the natural remanence magnetization (NRM) is a stable thermoremanent magnetization (TRM) carried by single domain (SD) like particles - is hard to test using non-destructive methods. Third, the interpretation of the experimental results is non-unique leading to uncertainty in the final paleointensity calculation. These experimental difficulties compound with dating problems, which are not always easy to overcome. Here, we address each of the issues pointed above in order to construct a high-resolution archaeointensity curve of the Levant using a comprehensive dataset consisting of more than 2000 specimens from over 400 samples. The experimental difficulties are overcome by applying the same treatments to all specimens: Thellier-type IZZI protocol with pTRM checks every second step, and additional anisotropy, cooling rate, and NLT experiments. To ensure consistency, comparability, and objectivity of the interpretations we apply an automatic data analysis technique using a recently published open code computer program (PmagPy Thellier-GUI). We use strict selection criteria for the specimens/samples level and for the correction to screen out any unreliable data. For transparency, we make all the raw data, which include over 80,000 individual measurements, available in the MagIC database for the use of other researchers. We treat the dating problems by assigning a six-level quality scale (form controversial to excellent

  4. An active state of the BL Lac Object Markarian 421 detected by INTEGRAL in April 2013

    CERN Document Server

    Pian, E; Fiocchi, M; Bazzano, A; Foschini, L; Tavecchio, F; Bianchin, V; Boissay, R; Castignani, G; Ferrigno, C; Raiteri, C M; Villata, M; Beckmann, V; D'Ammando, F; Hudec, R; Malaguti, G; Maraschi, L; Pursimo, T; Romano, P; Soldi, S; Stamerra, A; Treves, A; Ubertini, P; Vercellone, S; Walter, R

    2013-01-01

    (abridged) Multi-wavelength variability of blazars offers effective insight into the mechanisms through which energy is propagated from the center down the jet. In this context, we activated INTEGRAL observations of the blazar Markarian 421 in an active state on 16-21 April 2013, and complemented them with Fermi-LAT data. We obtained well sampled optical, soft and hard X-ray light curves that show the presence of two flares, the first one reaching a brighter maximum than the second one at X-rays. The average flux in the 20-100 keV range is 9.1e-11 cgs and the nuclear average apparent magnitude, corrected for Galactic extinction, is V ~ 12.2. In the time-resolved JEMX+IBIS spectra we see a change of spectral slope at an energy that correlates with flux, as expected in refreshed energy injections in a population of electrons that cool thereafter via synchrotron radiation. During the observation, the variability level increases monotonically from the optical to the hard X-rays, and the cross-correlation analysis...

  5. Testing the blazar sequence and black hole mass scaling with BL Lac objects

    NARCIS (Netherlands)

    Plotkin, R.M.; Markoff, S.; Anderson, S.F.; Kelly, B.C.; Körding, E.; Trager, S.C.

    2010-01-01

    Jets from accreting black holes appear remarkably similar over eight orders of magnitude in black hole mass, with more massive black holes generally launching more powerful jets. For example, there is an observed correlation, termed the fundamental plane of black hole accretion, between black hole

  6. Testing the blazar sequence and black hole mass scaling with BL Lac objects

    NARCIS (Netherlands)

    Plotkin, Richard M.; Markoff, Sera; Anderson, Scott F.; Kelly, Brandon C.; Körding, Elmar; Trager, Scott C.; Romero, Gustavo E.; Sunyaev, Rashid A.; Belloni, Tomaso

    Jets from accreting black holes appear remarkably similar over eight orders of magnitude in black hole mass, with more massive black holes generally launching more powerful jets. For example, there is an observed correlation, termed the fundamental plane of black hole accretion, between black hole

  7. Fractal Property in the Light Curve of BL Lac Object S5 0716+714

    Indian Academy of Sciences (India)

    J. W. Ou; Y. G. Zheng

    2014-09-01

    In this paper, we compile the historical R-band data of S5 0716+714 from literature and obtain its fractal dimension by using a fractal method and then simulate the data with the Weierstrass–Mandelbrot (W–M) function. It is considered that the light curve has a fractal property.

  8. Estimation of the extragalactic background light using TeV observations of BL Lac objects

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Atreyee; Acharya, B. S. [Department of High Energy Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Sahayanathan, S.; Godambe, S. [Astrophysical Sciences Division, Bhabha Atomic Research Center, Mumbai (India); Misra, R., E-mail: atreyee@tifr.res.in, E-mail: acharya@tifr.res.in, E-mail: sunder@barc.ernet.in, E-mail: gsagar@barc.ernet.in, E-mail: rmisra@iucaa.ernet.in [Inter-University Center for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411007 (India)

    2014-11-01

    The very high-energy (VHE) gamma-ray spectral index of high-energy peaked blazars correlates strongly with its corresponding redshift, whereas no such correlation is observed in the X-ray or GeV bands. We attribute this correlation to photon-photon absorption of TeV photons with the extragalactic background light (EBL), and utilizing this we compute the allowed flux range for the EBL, which is independent of previous estimates. The observed VHE spectrum of the sources in our sample can be well approximated by a power law, and if the de-absorbed spectrum is also assumed to be a power law, then we show that the spectral shape of EBL will be εn(ε) ∼ klog (ε/ε {sub p}). We estimate the range of values for the parameters defining the EBL spectrum, k and ε {sub p}, such that the correlation of the intrinsic VHE spectrum with redshift is nullified. The estimated EBL depends only on the observed correlation and the assumption of a power-law source spectrum. Specifically, it does not depend on the spectral modeling or radiative mechanism of the sources or on any theoretical shape of the EBL spectrum obtained through cosmological calculations. The estimated EBL spectrum is consistent with the upper and lower limits imposed by different observations. Moreover, it also agrees closely with the theoretical estimates obtained through cosmological evolution models.

  9. Fractal Property in the Light Curve of BL Lac Object S5 0716 + 714

    Science.gov (United States)

    Ou, J. W.; Zheng, Y. G.

    2014-09-01

    In this paper, we compile the historical R-band data of S5 0716 + 714 from literature and obtain its fractal dimension by using a fractal method and then simulate the data with the Weierstrass-Mandelbrot (W-M) function. It is considered that the light curve has a fractal property.

  10. Adaptive evolution of the Streptococcus pyogenes regulatory aldolase LacD.1.

    Science.gov (United States)

    Cusumano, Zachary; Caparon, Michael

    2013-03-01

    In the human-pathogenic bacterium Streptococcus pyogenes, the tagatose bisphosphate aldolase LacD.1 likely originated through a gene duplication event and was adapted to a role as a metabolic sensor for regulation of virulence gene transcription. Although LacD.1 retains enzymatic activity, its ancestral metabolic function resides in the LacD.2 aldolase, which is required for the catabolism of galactose. In this study, we compared these paralogous proteins to identify characteristics correlated with divergence and novel function. Surprisingly, despite the fact that these proteins have identical active sites and 82% similarity in amino acid sequence, LacD.1 was less efficient at cleaving both fructose and tagatose bisphosphates. Analysis of kinetic properties revealed that LacD.1's adaptation was associated with a decrease in k(cat) and an increase in K(m). Construction and analysis of enzyme chimeras indicated that non-active-site residues previously associated with the variable activities of human aldolase isoenzymes modulated LacD.1's affinity for substrate. Mutant LacD.1 proteins engineered to have LacD.2-like levels of enzymatic efficiency lost the ability to function as regulators, suggesting that an alteration in efficiency was required for adaptation. In competition under growth conditions that mimic a deep-tissue environment, LacD.1 conferred a significant gain in fitness that was associated with its regulatory activity. Taken together, these data suggest that LacD.1's adaptation represents a form of neofunctionalization in which duplication facilitated the gain of regulatory function important for growth in tissue and pathogenesis.

  11. SPECTROSCOPY OF BROAD-LINE BLAZARS FROM 1LAC

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, Michael S.; Romani, Roger W.; Healey, Stephen E.; Michelson, Peter F. [Department of Physics/KIPAC, Stanford University, Stanford, CA 94305 (United States); Cotter, Garret; Potter, William J. [Department of Astrophysics, University of Oxford, Oxford OX1 3RH (United Kingdom); Readhead, Anthony C. S.; Richards, Joseph L.; Max-Moerbeck, Walter; King, Oliver G. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)

    2012-03-20

    We report on optical spectroscopy of 165 flat spectrum radio quasars (FSRQs) in the Fermi 1LAC sample, which have helped allow a nearly complete study of this population. Fermi FSRQs show significant evidence for non-thermal emission even in the optical; the degree depends on the {gamma}-ray hardness. They also have smaller virial estimates of hole mass than the optical quasar sample. This appears to be largely due to a preferred (axial) view of the {gamma}-ray FSRQ and non-isotropic (H/R {approx} 0.4) distribution of broad-line velocities. Even after correction for this bias, the Fermi FSRQs show higher mean Eddington ratios than the optical population. A comparison of optical spectral properties with Owens Valley Radio Observatory radio flare activity shows no strong correlation.

  12. X-ray Flares of EV Lac: Statistics, Spectra, Diagnostics

    CERN Document Server

    Huenemoerder, David P; Testa, Paola; Drake, Jeremy J; Osten, Rachel A; Reale, Fabio

    2010-01-01

    We study the spectral and temporal behavior of X-ray flares from the active M-dwarf EV Lac in 200 ks of exposure with the Chandra/HETGS. We derive flare parameters by fitting an empirical function which characterizes the amplitude, shape, and scale. The flares range from very short (<1 ks) to long (10 ks) duration events with a range of shapes and amplitudes for all durations. We extract spectra for composite flares to study their mean evolution and to compare flares of different lengths. Evolution of spectral features in the density-temperature plane shows probable sustained heating. The short flares are significantly hotter than the longer flares. We determined an upper limit to the Fe K fluorescent flux, the best fit value being close to what is expected for compact loops.

  13. Radiocarbon measurements at LAC-UFF: Recent performance

    Energy Technology Data Exchange (ETDEWEB)

    Linares, Roberto, E-mail: rlinares@if.uff.br [Laboratório de Radiocarbono, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/n, Niterói 24230-346 (Brazil); Macario, Kita D. [Laboratório de Radiocarbono, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/n, Niterói 24230-346 (Brazil); Santos, Guaciara M. [Earth System Science, University of California, Irvine, B321 Croul Hall, Irvine, CA 92697-3100 (United States); Carvalho, Carla [Laboratório de Radiocarbono, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/n, Niterói 24230-346 (Brazil); Departamento de Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista, s/n, Niterói 24020-141 (Brazil); Santos, Hellen C. dos; Gomes, Paulo R.S.; Castro, Maikel D.; Oliveira, Fabiana M.; Alves, Eduardo Q. [Laboratório de Radiocarbono, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/n, Niterói 24230-346 (Brazil)

    2015-10-15

    In 2012 a single stage accelerator mass spectrometer from NEC was installed at the Radiocarbon Laboratory of Universidade Federal Fluminense (LAC-UFF), Niterói, Brazil. Here, we present a status report of our facility. We discuss some modifications applied to our combustion protocol in an attempt to reduce our procedural blank, mostly to processed organic samples. Measurements of reference materials indicate low precision and accuracy that are partially related to beam optics through the acceleration tube. We observed that once the beam current intensity increases the measured {sup 13}C{sup +}/{sup 12}C{sup +} becomes erratic. Therefore, in order to maintain the AMS-δ{sup 13}C values within reasonable values, so that fractionation corrections using the spectrometer {sup 13}C{sup +}/{sup 12}C{sup +} values does not affect the final {sup 14}C results, we are forced to limit the {sup 12}C{sup −} beam intensity to ⩽30 μA. This requirement was confirmed during our accuracy tests, when measuring selected annual tree-rings wood samples from a Parana pine (Araucaria angustifolia) between 1927 and 1997 previously measured at the Keck Carbon Cycle AMS Facility (KCCAMS), at the University of California, Irvine (UCI). At the LAC-UFF tree-ring wood samples were processed and measured in 4 different batches during a period of about 5 months. The {sup 14}C results were later compared to the high-precision data obtained at KCCAMS/UCI and reached a good agreement. Recently a problem associated with graphitization yield were finally identified and new measurements with secondary standards are promising.

  14. Helix dynamics in LacY: helices II/IV

    Science.gov (United States)

    Liu, Zhenyu; Madej, M. Gregor; Kaback, H. Ronald

    2011-01-01

    Biochemical and biophysical studies based upon crystal structures of both a mutant and wild-type lactose permease from Escherichia coli (LacY) in an inward-facing conformation have led to a model for the symport mechanism in which both sugar- and H+-binding sites are alternatively accessible to either side of the membrane. Previous findings indicate that the face of helix II with Asp68 is important for the conformational changes that occur during turnover. As shown here, replacement of Asp68 at the cytoplasmic end of helix II, particularly with Glu, abolishes active transport, but the mutants retain the ability to bind galactopyranoside. In the x-ray structure, Asp68 and Lys131 (helix IV) lie within ∼4.2 Å of each other. Although a double mutant with Cys replacements at both position 68 and 131 cross-links efficiently, single replacements for Lys131 exhibit very significant transport activity. Site-directed alkylation studies show that sugar binding by the Asp68 mutants causes closure of the cytoplasmic cavity, like wild-type LacY; but strikingly, the probability of opening the periplasmic pathway upon sugar binding is markedly reduced. Taken together with previous mutagenesis and cross-linking studies, the findings lead to a model in which replacement of Asp68 blocks a conformational transition involving helices II and IV that is important for opening the periplasmic cavity. Evidence is also presented suggesting that movements of helices II and IV are coupled functionally with movements in the pseudo-symmetrically paired helices VIII and X. PMID:20043916

  15. Observations of 1ES 1101-232 with H.E.S.S. and at lower frequencies: A hard spectrum blazar and constraints on the extragalactic background light

    Science.gov (United States)

    Pühlhofer, Gerd; Benbow, Wystan; Costamante, Luigi; Sol, Helene; Boisson, Catherine; Emmanoulopoulos, Dimitrios; Wagner, Stefan; Horns, Dieter; Giebels, Berrie

    VHE observations of the distant (z=0.186) blazar 1ES 1101-232 with H.E.S.S. are used to constrain the extragalactic background light (EBL) in the optical to near infrared band. As the EBL traces the galaxy formation history of the universe, galaxy evolution models can therefore be tested with the data. In order to measure the EBL absorption effect on a blazar spectrum, we assume that usual constraints on the hardness of the intrinsic blazar spectrum are not violated. We present an update of the VHE spectrum obtained with H.E.S.S. and the multifrequency data that were taken simultaneously with the H.E.S.S. measurements. The data verify that the broadband characteristics of 1ES 1101-232 are similar to those of other, more nearby blazars, and strengthen the assumptions that were used to derive the EBL upper limit.

  16. lac repressor is an antivirulence factor of Salmonella enterica: its role in the evolution of virulence in Salmonella.

    Directory of Open Access Journals (Sweden)

    Sandeepa M Eswarappa

    Full Text Available The genus Salmonella includes many pathogens of great medical and veterinary importance. Bacteria belonging to this genus are very closely related to those belonging to the genus Escherichia. lacZYA operon and lacI are present in Escherichia coli, but not in Salmonella enterica. It has been proposed that Salmonella has lost lacZYA operon and lacI during evolution. In this study, we have investigated the physiological and evolutionary significance of the absence of lacI in Salmonella enterica. Using murine model of typhoid fever, we show that the expression of LacI causes a remarkable reduction in the virulence of Salmonella enterica. LacI also suppresses the ability of Salmonella enterica to proliferate inside murine macrophages. Microarray analysis revealed that LacI interferes with the expression of virulence genes of Salmonella pathogenicity island 2. This effect was confirmed by RT-PCR and Western blot analysis. Interestingly, we found that SBG0326 of Salmonella bongori is homologous to lacI of Escherichia coli. Salmonella bongori is the only other species of the genus Salmonella and it lacks the virulence genes of Salmonella pathogenicity island 2. Overall, our results demonstrate that LacI is an antivirulence factor of Salmonella enterica and suggest that absence of lacI has facilitated the acquisition of virulence genes of Salmonella pathogenicity island 2 in Salmonella enterica making it a successful systemic pathogen.

  17. The Sedentary Survey of Extreme High Energy Peaked BL Lacs. II. The Catalog and Spectral Properties

    CERN Document Server

    Giommi, P; Perri, M; Padovani, P

    2004-01-01

    The multi-frequency `Sedentary Survey' is a deep, statistically complete, radio flux limited sample comprising 150 BL Lacertae objects distinguished by their extremely high X-ray to radio flux ratio, ranging from five hundred to over five thousand times that of typical BL Lacs discovered in radio surveys. This paper presents the final, 100% identified, catalog together with the optical, X-ray and broad-band SEDs constructed combining literature multi-frequency data with non-simultaneous optical observations and BeppoSAX X-ray data, when available. The SEDs confirm that the peak of the synchrotron power in these objects is located at very high energies. BeppoSAX wide band X-ray observations show that, in most cases, the X-ray spectra are convex and well described by a logarithmic parabola model peaking (in a E f(E) vs E representation) between 0.02 to several keV. Owing to the high synchrotron energies involved most of the sources in the catalog are likely to be TeV emitters, with the closest and brightest one...

  18. H.E.S.S and Fermi-LAT discovery of gamma rays from the blazar 1ES 1312-423

    CERN Document Server

    Abramowski, A; Aharonian, F; Akhperjanian, A G; Angüner, E; Anton, G; Balenderan, S; Balzer, A; Barnacka, A; Becherini, Y; Tjus, J Becker; Bernlöhr, K; Birsin, E; Bissaldi, E; Biteau, J; Boisson, C; Bolmont, J; Bordas, P; Brucker, J; Brun, F; Brun, P; Bulik, T; Carrigan, S; Casanova, S; Cerruti, M; Chadwick, P M; Chalme-Calvet, R; Chaves, R C G; Cheesebrough, A; Chrétien, M; Colafrancesco, S; Cologna, G; Conrad, J; Couturier, C; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; deWilt, P; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Edwards, T; Egberts, K; Eger, P; Espigat, P; Farnier, C; Fegan, S; Feinstein, F; Fernandes, M V; Fernandez, D; Fiasson, A; Fontaine, G; Förster, A; Füßling, M; Gajdus, M; Gallant, Y A; Garrigoux, T; Gast, H; Giebels, B; Glicenstein, J F; Göring, D; Grondin, M -H; Grudzińska, M; Häffner, S; Hague, J D; Hahn, J; Harris, J; Heinzelmann, G; Henri, G; Hermann, G; Hervet, O; Hillert, A; Hinton, J A; Hofmann, W; Hofverberg, P; Holler, M; Horns, D; Jacholkowska, A; Jahn, C; Jamrozy, M; Janiak, M; Jankowsky, F; Jung, I; Kastendieck, M A; Katarzyński, K; Katz, U; Kaufmann, S; Khélifi, B; Kieffer, M; Klepser, S; Klochkov, D; Kluźniak, W; Kneiske, T; Kolitzus, D; Komin, Nu; Kosack, K; Krakau, S; Krayzel, F; Krüger, P P; Laffon, H; Lamanna, G; Lefaucheur, J; Lemoine-Goumard, M; Lenain, J -P; Lennarz, D; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Maurin, G; Maxted, N; Mayer, M; McComb, T J L; Medina, M C; Méhault, J; Menzler, U; Meyer, M; Moderski, R; Mohamed, M; Moulin, E; Murach, T; Naumann, C L; de Naurois, M; Nedbal, D; Niemiec, J; Nolan, S J; Oakes, L; Ohm, S; de OñaWilhelmi, E; Opitz, B; Ostrowski, M; Oya, I; Panter, M; Parsons, R D; Arribas, M Paz; Pekeur, N W; Pelletier, G; Perez, J; Petrucci, P -O; Peyaud, B; Pita, S; Poon, H; Pühlhofer, G; Punch, M; Quirrenbach, A; Raab, S; Raue, M; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Sahakian, V; Sanchez, D A; Santangelo, A; Schlickeiser, R; Schüssler, F; Schulz, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Sol, H; Spengler, G; Spieß, F; Stawarz, {Ł }; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Szostek, A; Tavernet, J -P; Terrier, R; Tluczykont, M; Trichard, C; Valerius, K; van Eldik, C; Vasileiadis, G; Venter, C; Viana, A; Vincent, P; Völk, H J; Volpe, F; Vorster, M; Wagner, S J; Wagner, P; Ward, M; Weidinger, M; White, R; Wierzcholska, A; Willmann, P; Wörnlein, A; Wouters, D; Zacharias, M; Zajczyk, A; Zdziarski, A A; Zech, A; Zechlin, H -S; Perkins, J S; Ojha, R; Stevens, J; Edwards, P G; Kadler, M

    2013-01-01

    A deep observation campaign carried out by the High Energy Stereoscopic System (H.E.S.S.) on Centaurus A enabled the discovery of gamma rays from the blazar 1ES 1312-423, two degrees away from the radio galaxy. With a differential flux at 1 TeV of (1.9 +/-0.6(stat) +/-0.4(sys)) x 10^{-13} /cm^2 /s /TeV corresponding to 0.5% of the Crab nebula differential flux and a spectral index of 2.9 +/- 0.5 (stat) +/- 0.2 (sys), 1ES 1312-423 is one of the faintest sources ever detected in the very high energy (E>100 GeV) extragalactic sky. A careful analysis using three and a half years of Fermi-LAT data allows the discovery at high energies (E>100 MeV) of a hard spectrum (index of 1.4 +/- 0.4 (stat) +/- 0.2 (sys)) source coincident with 1ES 1312-423. Radio, optical, UV and X-ray observations complete the spectral energy distribution of this blazar, now covering 16 decades in energy. The emission is successfully fitted with a synchrotron self Compton model for the non-thermal component, combined with a black-body spectru...

  19. The BL-Lac gamma-ray blazar PKS 1424+240 associated with a group of galaxies at z=0.6010

    CERN Document Server

    Rovero, A C; Donzelli, C; Pichel, A

    2016-01-01

    PKS 1424+240 is a BL-Lac blazar with unknown redshift that was detected at high-energy gamma rays by Fermi-LAT with a hard spectrum. At VHE, it was first detected by VERITAS and later confirmed by MAGIC. Its spectral energy distribution is highly attenuated at VHE gamma rays, which is coherent with distant sources. Several estimations enabled the redshift to be constrained to the range 0.6 < z < 1.3. These results place PKS 1424+240 in the very interesting condition of being probably the most distant blazar that has been detected at VHE. The ambiguity in the redshift is still large enough to prevent precise studies of the EBL and the intrinsic blazar spectrum. Given the difficulty of measuring spectroscopic redshifts for BL-Lac objects directly, we aim to establish a reliable redshift value for this blazar by finding its host group of galaxies. Elliptical galaxies are associated with groups, and BL-Lac objects are typically hosted by them, so we decided to search for the host group of the blazar. For th...

  20. Narrative Report : Des Lacs National Wildlife Refuge Complex for Fiscal Year 1975 [including July - December 1975

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1975 fiscal and calendar year. The report begins by...

  1. Photometric Analysis and Period Investigation of the EW Type Eclipsing Binary V441 Lac

    Indian Academy of Sciences (India)

    K. Li; S.-M. Hu; D.-F. Guo; Y.-G. Jiang; D.-Y. Gao; X. Chen

    2016-09-01

    Four color light curves of the EW type eclipsing binary V441Lac were presented and analyzed by the W--D code. It is found that V441Lac is an extremely low mass ratio $(q = 0.093 \\pm 0.001)$ semi-detached binary with the less massive secondary component filling the inner Roche lobe. Two dark spots on the primary component were introduced to explain the asymmetric light curves. By analyzing all times of light minimum, we determined that the orbital period of V441 Lac is continuously increasing at a rate of ${\\rm d}P/{\\rm d}t = 5.874(\\pm 0.007)\\times 10^{--7} {\\rm d yr}^{--1}$. The semidetached Algol type configuration of V441 Lac is possibly formed by a contact configuration destroyed shallow contact binary due to mass transfer from the less massive component to the more massive one predicted by the thermal relaxation oscillation theory.

  2. Mille Lacs and Rice Lake National Wildlife Refuges Wilderness study summary

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a summary of a wilderness study done of Mille Lacs and Rice Lake National Wildlife Refuges pursuant to the Wilderness Act of 1964. It provides...

  3. Narrative report May, June, July, August, 1948 Des Lacs National Wildlife Refuge & Easement Refuges - District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from May through August of 1948. The report begins by summarizing the...

  4. Sustaining the natural and economical resources of the Lac Courte Oreilles, Leslie Isham; Jason Weaver

    Energy Technology Data Exchange (ETDEWEB)

    Isham, Leslie; Weaver, Jason

    2013-09-30

    The Lac Courte Oreilles Band of Lake Superior Chippewa Indians, located in northwest Wisconsin has developed a project, entitled Sustaining the Natural and Economic Resources of the LCO Ojibwe. This technical report is a summary of the project.

  5. Whistling swan population records 1959-1969 : Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a population record of whistling/tundra swans seen at Des Lacs National Wildlife Reufge between 1959 and 1969. Year and season, arrival date, and...

  6. Des Lacs National Wildlife Refuge: Annual narrative report: Calendar year 2000

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge summarizes Refuge activities during the 2000 calendar year. The report begins with a summary of...

  7. Des Lacs National Wildlife Refuge : Annual narrative report : Calendar year 2004

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge summarizes Refuge activities during the 2004 calendar year. The report begins with a summary of...

  8. Des Lacs National Wildlife Refuge : Annual narrative report : Calendar year 2007

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge summarizes Refuge activities during the 2007 calendar year. The report begins with a summary of...

  9. Des Lacs National Wildlife Refuge: Annual narrative report: Calendar year 1998

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge summarizes Refuge activities during the 1998 calendar year. The report begins with a summary of...

  10. [Draft letter to President: Mille Lacs and Rice Lake National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a draft letter from the Secretary of the Interior to the President regarding the establishment of the Mille Lacs and Rice Lake Wilderness area. The...

  11. Fact sheet : Wilderness proposal : Rice Lake - Mille Lacs National Wildlife Refuges

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a fact sheet of information about the Rice Lake and Mille Lacs National wildlife Refuges. Pertinent information such as the area of the refuge,...

  12. Rice Lake National Wildlife Refuge (including Mille Lacs and Sandstone): Annual narrative report: Calendar year 1986

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Rice Lake NWR and Mille Lacs NWR outlines Refuge accomplishments during the 1986 calendar year. The report begins with a summary of...

  13. Des Lacs National Wildlife Refuge : Annual Narrative Report : Calendar Year 1977

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1977 calendar year. The report begins with an introduction to...

  14. Narrative Report : Fiscal Year 1974 : Des Lacs National Wildlife Refuge Complex

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1974 fiscal year. The report begins by summarizing the...

  15. Narrative report for September, October, November and December 1944 Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from September through December of 1944. The report begins by summarizing...

  16. Rice Lake National Wildlife Refuge : Sandstone Unit : Mille Lacs National Wildlife Refuge : Fiscal year 2002

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Rice Lake (including the Sandstone Unit) and Mille Lacs National Wildlife Refuges outlines Refuge accomplishments during the 2002...

  17. Des Lacs National Wildlife Refuge: Annual narrative report: Calendar year 1990

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1990 calendar year. The report begins with a summary of...

  18. Narrative report for January, February, March and April 1945 Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from January through April of 1945. The report begins by summarizing the...

  19. 1997-1998 lake water quality assessment for Upper Des Lacs Lake, North Dakota

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This is a summary of the data collected on Upper Des Lacs Lake as part of the State's Lake Water Quality Assessment Project. The Project is designed to characterize...

  20. Des Lacs National Wildlife Refuge: Annual narrative report: Calendar year 1994

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1994 calendar year. The report begins with a summary of...

  1. Des Lacs National Wildlife Refuge : Annual narrative report : Calendar year 2003

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge summarizes Refuge activities during the 2003 calendar year. The report begins with a summary of...

  2. Rice Lake National Wildlife Refuge (including Mille Lacs and Sandstone): Annual narrative report: Calendar year 1988

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Rice Lake National Wildlife Refuge and Mille Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1988 calendar...

  3. Weekly observations relative to duck sickness [Des Lacs National Wildlife Refuge 1940

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This data set is of handwritten data sheets for weekley botulism observations at Des Lacs National Wildlife Refuge, for the summer of 1940.

  4. Des Lacs National Wildlife Refuge: Annual narrative report: Calendar year 1992

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1992 calendar year. The report begins with a summary of...

  5. Narrative report May, June, July, August, 1946 Des Lacs National Wildlife Refuge & Easement Refuges - District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from May through August of 1946. The report begins by summarizing the...

  6. Narrative report January, February, March, April, 1949 Des Lacs National Wildlife Refuge & Easement Refuges - District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge and Ilo Lake National Wildlife Refuge outlines Refuge accomplishments from January through April of...

  7. Preliminary report of the biological development of the Des Lacs, Upper Souris, and Lostwood Refuges

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Preliminary report on the development of Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, and Upper Souris National Wildlife Refuge. This report...

  8. Rice Lake National Wildlife Refuge (including Mille Lacs and Sandstone): Annual narrative report: Calendar year 1990

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Rice Lake National Wildlife Refuge and Mille Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1990 calendar...

  9. Rice Lake National Wildlife Refuge (including Mille Lacs and Sandstone): Annual narrative report: Calendar year 1991

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Rice Lake National Wildlife Refuge and Mille Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1991 calendar...

  10. Des Lacs National Wildlife Refuge : Annual Narrative Report : Calendar Year 1987

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1987 calendar year. The report begins with a summary of...

  11. Des Lacs National Wildlife Refuge: Annual narrative report: Calendar year 2001

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge summarizes Refuge activities during the 2001 calendar year. The report begins with a summary of...

  12. Des Lacs Nat'l Wildlife Refuge : Narrative Report for Calendar Year 1972

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1972 calendar year. The report begins by summarizing...

  13. Rice Lake National Wildlife Refuge (including Mille Lacs and Sandstone): Annual narrative report: Calendar year 1989

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Rice Lake National Wildlife Refuge and Mille Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1989 calendar...

  14. Rice Lake National Wildlife Refuge, Mille Lacs Refuge, Sandstone Unit: [Narrative report: 1970

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Rice Lake NWR and Mille Lacs NWR outlines Refuge accomplishments during the 1970 calendar year. The report begins by summarizing the...

  15. Narrative report May, June, July, August, 1949, Des Lacs National Wildlife Refuge & Easement Refuges - District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from May through August of 1949. The report begins by summarizing the...

  16. Rice Lake National Wildlife Refuge (including Mille Lacs and Sandstone): Annual narrative report: Calendar year 1985

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Rice Lake NWR and Mille Lacs NWR outlines Refuge accomplishments during the 1985 calendar year. The report begins with a summary of...

  17. Rice Lake National Wildlife Refuge (including Mille Lacs and Sandstone): Annual narrative report: Calendar year 1987

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Rice Lake NWR and Mille Lacs NWR outlines Refuge accomplishments during the 1987 calendar year. The report begins with a summary of...

  18. Rice Lake National Wildlife Refuge : Mille Lacs National Wildlife Refuge : Sandstone Unit : Fiscal year 2003

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Rice Lake (including the Sandstone Unit) and Mille Lacs National Wildlife Refuges outlines Refuge accomplishments during the 2003...

  19. Integrated Pest Management Plan 2005-2010 Des Lacs National Wildlife Refuge Complex

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of the Integrated Pest Management Plan is to provide a comprehensive, environmentally sensitive approach to managing pests on the Des Lacs NWRC. The...

  20. Planning and accomplishment narrative : January 1 - June 30, 1973 : Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This planning and accomplishment report for Des Lacs National Wildlife Refuge outlines Refuge activities from January 1st through June 30th, 1973. The report begins...

  1. Des Lacs National Wildlife Refuge : Annual narrative report : Calendar year 2002

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge summarizes Refuge activities during the 2002 calendar year. The report begins with a summary of...

  2. Des Lacs National Wildlife Refuge : Annual Narrative Report : Calendar Year 1983

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1983 calendar year. The report begins with a summary of...

  3. Habitat characteristics of prairie-woodland edges at Des Lacs National Wildlife Refuge, North Dakota

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Little is known about the vegetation structure and composition of prairie-woodland transition areas at Des Lacs National Wildlife Refuge (DLNWR) in northwestern...

  4. Biological report on the Des Lacs Migratory Bird Refuge August, 1936

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs NWR and Lostwood NWR summarizes activities on the refuges during August of 1936. Water conditions, seed collecting, and waterfowl...

  5. Winter report on biological projects : Des Lacs and Lostwood Migratory Bird Refuge : 1935-1936

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Report on biological projects taking place during the winter of 1935-1936 on Des Lacs National Wildlife Refuge and Lostwood National Wildlife Refuge. Activities...

  6. Narrative report May, June, July, August, 1952 Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from May through August of 1952. The report begins by summarizing the...

  7. 1954 Progress report : Fishery management program : Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Progress report for the fishery management program at Des Lacs National Wildlife Refuge. This report is a result of a site visit to continue fish population studies...

  8. Rice Lake National Wildlife Refuge : Mille Lacs National Wildlife Refuge : Sandstone Unit : Fiscal year 2004

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Rice Lake (including the Sandstone Unit) and Mille Lacs National Wildlife Refuges outlines Refuge accomplishments during the 2004...

  9. Des Lacs National Wildlife Refuge : Annual narrative report : Calendar year 2006

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge summarizes Refuge activities during the 2006 calendar year. The report begins with a summary of...

  10. Des Lacs National Wildlife Refuge : Annual narrative report : Calendar year 2005

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge summarizes Refuge activities during the 2005 calendar year. The report begins with a summary of...

  11. Narrative report September, October, November, December, 1950 Des Lacs National Wildlife Refuge & Easement Refuges - District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from September through December of 1950. The report begins by summarizing...

  12. Narrative report January, February, March, April, 1948 Des Lacs National Wildlife Refuge & Easement Refuges - District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from January through April of 1948. The report begins by summarizing the...

  13. Narrative report January, February, March, April, 1946 Des Lacs National Wildlife Refuge & Easement Refuges - District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from January through April of 1946. The report begins by summarizing the...

  14. 94th Congress : 1st Session : S. 1034 [Rice Lake and Mille Lacs National Wildlife Refuges

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a bill meant to designate Rice Lake and Mille Lacs National Wildlife Refuges as wilderness. It was introduced in the 94th Congress by Mr. Haskell....

  15. Des Lacs National Wildlife Refuge : Annual Narrative Report : Calendar Year 1985

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1985 calendar year. The report begins with a summary of...

  16. Parcels and Land Ownership, Digital mapping planned, but n, Published in 2008, Mille Lacs County Government.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Parcels and Land Ownership dataset as of 2008. It is described as 'Digital mapping planned, but n'. The extent of these data is generally Mille Lacs County, MN....

  17. Notice of public hearing regarding wilderness proposal : Rice Lake and Mille Lacs National Wildlife Refuges

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document contains two different announcements for the Rice Lake and Mille Lacs Wilderness area public hearing. The first is a notice for the Federal Register,...

  18. Preliminary fish survey of Lac Tseny in northwestern Madagascar

    Directory of Open Access Journals (Sweden)

    Noromalala Raminosoa

    2011-12-01

    Full Text Available We surveyed the fish fauna of Lac Tseny, in the Sofia Region of northwestern Madagascar, during October 2010 by observing commercial catches and targeted netting of areas used by endemic species. We recorded seven native fish species at the lake, including three endemic cichlids, a herring and a catfish. We confirmed the continued survival of the Critically Endangered Paretroplus menarambo, as well as the presence of a Paretroplus taxon that may be new to science. The commercial fishery in the lake is sustained by introduced tilapiines and the native Savagella robusta. The three endemic cichlids (Paretroplus spp. were not targeted by commercial fishermen, but when caught in small numbers were retained for domestic consumption. Submerged trees in the west of the lake restrict fishing with nets and probably provide important habitat for P. menarambo. Priority next steps at the lake include (i additional surveys and biological studies of the endemic fish species and the Critically Endangered Madagascar big-headed turtle, Erymnochelys madagascariensis, (ii clarification of the taxonomic status of Paretroplus cf. kieneri and, should it prove a new taxon, its formal scientific description, and (iii continued engagement with fishing communities and authorities to promote practices that benefit livelihoods and the survival of threatened fish species.

  19. Site-specific mutagenesis of histidine residues in the lac permease of Escherichia coli.

    OpenAIRE

    Padan, E; Sarkar, H K; Viitanen, P V; Poonian, M S; Kaback, H. R.

    1985-01-01

    The lacY gene of Escherichia coli, which encodes the lac permease, has been modified by oligonucleotide-directed, site-specific mutagenesis such that each of the four histidine residues in the molecule is replaced with an arginine residue. Replacement of histidine-35 and histidine-39 with arginine has no apparent effect on permease activity. In contrast, replacement of either histidine-205 or histidine-322 by arginine causes a dramatic loss of transport activity, although the cells contain a ...

  20. Regulation of endothelial-specific transgene expression by the LacI repressor protein in vivo.

    Directory of Open Access Journals (Sweden)

    Susan K Morton

    Full Text Available Genetically modified mice have played an important part in elucidating gene function in vivo. However, conclusions from transgenic studies may be compromised by complications arising from the site of transgene integration into the genome and, in inducible systems, the non-innocuous nature of inducer molecules. The aim of the present study was to use the vascular system to validate a technique based on the bacterial lac operon system, in which transgene expression can be repressed and de-repressed by an innocuous lactose analogue, IPTG. We have modified an endothelium specific promoter (TIE2 with synthetic LacO sequences and made transgenic mouse lines with this modified promoter driving expression of mutant forms of connexin40 and an independently translated reporter, EGFP. We show that tissue specificity of this modified promoter is retained in the vasculature of transgenic mice in spite of the presence of LacO sequences, and that transgene expression is uniform throughout the endothelium of a range of adult systemic and cerebral arteries and arterioles. Moreover, transgene expression can be consistently down-regulated by crossing the transgenic mice with mice expressing an inhibitor protein LacI(R, and in one transgenic line, transgene expression could be de-repressed rapidly by the innocuous inducer, IPTG. We conclude that the modified bacterial lac operon system can be used successfully to validate transgenic phenotypes through a simple breeding schedule with mice homozygous for the LacI(R protein.

  1. Multiwavelength Intraday Variability of the BL Lac S5 0716+714

    CERN Document Server

    Gupta, Alok C; Wiita, P J; Rani, B; Sokolovsky, K V; Mohan, P; Mangalam, A; Marchili, N; Fuhrmann, L; Agudo, I; Bach, U; Bachev, R; Böttcher, M; Gabanyi, K E; Gaur, H; Hawkins, K; Kimeridze, G N; Kurtanidze, O M; Kurtanidze, S O; Lee, C -U; Liu, X; McBreen, B; Nesci, R; Nestoras, G; Nikolashvili, M G; Ohlert, J M; Palma, N; Peneva, S; Pursimo, T; Semkov, E; Strigachev, A; Webb, J R; Wiesemeyer, H; Zensus, J A

    2012-01-01

    We report results from a 1 week multi-wavelength campaign to monitor the BL Lac object S5 0716+714 (on December 9-16, 2009). In the radio bands the source shows rapid (~ (0.5-1.5) day) intra-day variability with peak amplitudes of up to ~ 10 %. The variability at 2.8 cm leads by about 1 day the variability at 6 cm and 11 cm. This time lag and more rapid variations suggests an intrinsic contribution to the source's intraday variability at 2.8 cm, while at 6 cm and 11 cm interstellar scintillation (ISS) seems to predominate. Large and quasi-sinusoidal variations of ~ 0.8 mag were detected in the V, R and I-bands. The X-ray data (0.2-10 keV) do not reveal significant variability on a 4 day time scale, favoring reprocessed inverse-Compton over synchrotron radiation in this band. The characteristic variability time scales in radio and optical bands are similar. A quasi-periodic variation (QPO) of 0.9 - 1.1 days in the optical data may be present, but if so it is marginal and limited to 2.2 cycles. Cross-correlatio...

  2. X-Ray Spectral Variability of Extreme BL Lac AGN H1426+428

    CERN Document Server

    Falcone, A D; Finley, J P

    2004-01-01

    Between 7 March 2002 and 15 June 2002, intensive X-ray observations were carried out on the extreme BL Lac object H1426+428 with instruments on board the Rossi X-ray Timing Explorer (RXTE). These instruments provide measurements of H1426+428 in the crucial energy range that characterizes the first peak of its spectral energy distribution. This peak, which is almost certainly due to synchrotron emission, has previously been inferred to be in excess of 100 keV. By taking frequent observations over a four-month campaign, which included $\\sim$450 ksec of RXTE time, studies of flux and spectral variability on multiple timescales were performed, along with studies of spectral hysteresis. The 3-24 keV X-ray flux and spectra exhibited significant variability, implying variability in the location of the first peak of the spectral energy distribution. Hysteresis patterns were observed, and their characteristics have been discussed within the context of emission models.

  3. The pc-scale structure and evolution of BL Lac PKS 0003-066

    CERN Document Server

    Horiuchi, S; West, C J; Tzioumis, A K; Phillips, C J; Lovell, J E J; Reynolds, J E; Ellingsen, S P; Reid, P B; Cimo, G; Quick, J F H; Koyama, Y; Briggs, F H; Brisken, W F

    2006-01-01

    We present the results of global VLBI observations of the BL Lac object PKS 0003-066 at 2.3 and 8.6 GHz, over a 10 year period using data from new and archived VLBA, geodetic VLBI, and global VLBI (including the use of new disk-based recording and software correlation systems) observations. Inter-continental baselines resolve this source into a compact core and three jet components that move away from the core with proper motions ranging between \\~0.1 mas/yr for the outer jet component and ~1.4 mas/yr for the fastest inner jet component, i.e. apparent speeds of ~2.0 c to ~21.6 c respectively. This result is in contrast to previous studies of this source which did not reveal significant jet motions from limited data sets. We find that the fast inner jet components catch up to the more slowly moving outer jet components and interact strongly, causing local brightening of the jet in the interaction. We document the body of VLBI data for this source, as well as other supporting radio observations, as a basis for ...

  4. Genotype to phenotype mapping and the fitness landscape of the E. coli lac promoter.

    Directory of Open Access Journals (Sweden)

    Jakub Otwinowski

    Full Text Available Genotype-to-phenotype maps and the related fitness landscapes that include epistatic interactions are difficult to measure because of their high dimensional structure. Here we construct such a map using the recently collected corpora of high-throughput sequence data from the 75 base pairs long mutagenized E. coli lac promoter region, where each sequence is associated with its phenotype, the induced transcriptional activity measured by a fluorescent reporter. We find that the additive (non-epistatic contributions of individual mutations account for about two-thirds of the explainable phenotype variance, while pairwise epistasis explains about 7% of the variance for the full mutagenized sequence and about 15% for the subsequence associated with protein binding sites. Surprisingly, there is no evidence for third order epistatic contributions, and our inferred fitness landscape is essentially single peaked, with a small amount of antagonistic epistasis. There is a significant selective pressure on the wild type, which we deduce to be multi-objective optimal for gene expression in environments with different nutrient sources. We identify transcription factor (CRP and RNA polymerase binding sites in the promotor region and their interactions without difficult optimization steps. In particular, we observe evidence for previously unexplored genetic regulatory mechanisms, possibly kinetic in nature. We conclude with a cautionary note that inferred properties of fitness landscapes may be severely influenced by biases in the sequence data.

  5. Molecular phylogeny and biogeography of lac insects (Hemiptera: Kerriidae) inferred from nuclear and mitochondrial gene sequences.

    Science.gov (United States)

    Chen, Hang; Chen, Xiaoming; Feng, Ying; Yang, Hui; He, Rui; Zhang, Wenfeng; Yang, Zixiang

    2013-10-01

    Lac insects are commercial scale insects with high economic value. The combined molecular phylogeny of 20 lac insect populations was generated using elongation factor 1 alpha, mitochondrial cytochrome c oxidase subunit I and the small subunit ribosomal RNA gene loci. The 20 populations of lac insects clustered into four distinct clades supported by high bootstrap values in maximum parsimony, maximum likelihood and Bayesian analyses. Clade A at the base of the dendrogram comprises Kerria ruralis and two populations of Kerria lacca and is the branch with most primitive species. Clade B includes K. lacca, Kerria sindica and the three populations P, V and Z from India. They clustered with high bootstrap support and have evolved later than those in Clade A. The three unidentified populations P, V and Z exhibited a close relationship with K. lacca and are the same species. In Clade C, three populations of Kerria yunnanensis (Ym, Yj and Yl), population Ys from Thailand and population H from India clustered as a group, in which population H clustered with Ym with 100 % bootstrap in all three analysis methods. In Clade D, Kerria chinensis, Kerria pusana and three populations of K. yunnanensis clustered together with strong support, and are located in the upper branches of the dendrogram and are recently evolved taxa. The majority of populations from the Indian subcontinent clade are more closely related to outgroup taxa from the primitive family Pseudococcidae, as compared to the Eurasian populations. Phylogenetic analysis reveals that the Indian subcontinent is the centre of original of lac insects which have translocated to the Eurasian Continent. Based on the theory of continental drift and existing fossil records, it is suggested that lac insect evolved from ancient scale insects during the late Cretaceous period when the Indian subcontinent drifted towards the Eurasian Continent. Changes in the global environment have impacted on the distribution and evolution of lac

  6. Aflatoxin B1 and M1 Degradation by Lac2 from Pleurotus pulmonarius and Redox Mediators

    Science.gov (United States)

    Loi, Martina; Fanelli, Francesca; Zucca, Paolo; Liuzzi, Vania C.; Quintieri, Laura; Cimmarusti, Maria T.; Monaci, Linda; Haidukowski, Miriam; Logrieco, Antonio F.; Sanjust, Enrico; Mulè, Giuseppina

    2016-01-01

    Laccases (LCs) are multicopper oxidases that find application as versatile biocatalysts for the green bioremediation of environmental pollutants and xenobiotics. In this study we elucidate the degrading activity of Lac2 pure enzyme form Pleurotus pulmonarius towards aflatoxin B1 (AFB1) and M1 (AFM1). LC enzyme was purified using three chromatographic steps and identified as Lac2 through zymogram and LC-MS/MS. The degradation assays were performed in vitro at 25 °C for 72 h in buffer solution. AFB1 degradation by Lac2 direct oxidation was 23%. Toxin degradation was also investigated in the presence of three redox mediators, (2,2′-azino-bis-[3-ethylbenzothiazoline-6-sulfonic acid]) (ABTS) and two naturally-occurring phenols, acetosyringone (AS) and syringaldehyde (SA). The direct effect of the enzyme and the mediated action of Lac2 with redox mediators univocally proved the correlation between Lac2 activity and aflatoxins degradation. The degradation of AFB1 was enhanced by the addition of all mediators at 10 mM, with AS being the most effective (90% of degradation). AFM1 was completely degraded by Lac2 with all mediators at 10 mM. The novelty of this study relies on the identification of a pure enzyme as capable of degrading AFB1 and, for the first time, AFM1, and on the evidence that the mechanism of an effective degradation occurs via the mediation of natural phenolic compounds. These results opened new perspective for Lac2 application in the food and feed supply chains as a biotransforming agent of AFB1 and AFM1. PMID:27563923

  7. WHAT IS THE REDSHIFT OF THE GAMMA-RAY BL LAC SOURCE S4 0954+65?

    Energy Technology Data Exchange (ETDEWEB)

    Landoni, M. [INAF—Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate (Italy); Falomo, R. [INAF—Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova (Italy); Treves, A. [Universita’ degli Studi dell’Insubria, Via Valleggio 11, I-22100 (Italy); Scarpa, R.; Payá, D. Reverte, E-mail: marco.landoni@brera.inaf.it [Instituto de Astrofsica de Canarias, C/O Via Lactea, s/n E38205—La Laguna (Tenerife) (Spain)

    2015-12-15

    High signal-to-noise ratio spectroscopic observations of the BL Lac object S4 0954+65 at the alleged redshift z = 0.367 are presented. This source was detected at gamma frequencies by the MAGIC (TeV) and FERMI (GeV) telescopes during a remarkable outburst that occurred in 2015 February, making the determination of its distance particularly relevant for our understanding of the properties of the extragalactic background light. Contrary to previous reports on the redshift, we found that the optical spectrum is featureless at an equivalent width limit of ∼0.1 Å. A critical analysis of the existing observations indicates that the redshift is still unknown. Based on the new data we estimate a lower limit to the redshift at z ≥ 0.45.

  8. Reproductive attitudes of couples having a child with cystic fibrosis in Saguenay-Lac-Saint-Jean (Quebec, Canada).

    Science.gov (United States)

    De Braekeleer, M; Bellis, G; Rault, G; Allard, C; Milot, M; Simard, F

    2000-01-01

    Cystic fibrosis (CF) has a high incidence (1/936 live births) and carrier rate (1/15 inhabitants) in Saguenay-Lac-Saint-Jean. One objective of a major enquiry among several subsets of individuals from this high-risk population for CF was to evaluate the reproductive behaviour of couples with a CF child attending the comprehensive CF clinic in Chicoutimi. The knowledge of the recurrence risk resulted in deciding against further progeny or in reducing the number of children. More reliable contraception methods after the birth of the CF child, but not prenatal diagnosis, were used. Although a minority of parents with a CF child would abort a CF foetus, they apparently started viewing pregnancy interruption for CF after prenatal diagnosis as an acceptable reproductive option.

  9. Polymorphisms in the LAC12 gene explain lactose utilisation variability in Kluyveromyces marxianus strains.

    Science.gov (United States)

    Varela, Javier A; Montini, Noemi; Scully, Damhan; Van der Ploeg, Ralph; Oreb, Mislav; Boles, Eckhard; Hirota, Junya; Akada, Rinji; Hoshida, Hisashi; Morrissey, John P

    2017-05-01

    Kluyveromyces marxianus is a safe yeast used in the food and biotechnology sectors. One of the important traits that sets it apart from the familiar yeasts, Saccharomyces cerevisiae, is its capacity to grow using lactose as a carbon source. Like in its close relative, Kluyveromyces lactis, this requires lactose transport via a permease and intracellular hydrolysis of the disaccharide. Given the importance of the trait, it was intriguing that most, but not all, strains of K. marxianus are reported to consume lactose efficiently. In this study, primarily through heterologous expression in S. cerevisiae and K. marxianus, it was established that a single gene, LAC12, is responsible for lactose uptake in K. marxianus. Strains that failed to transport lactose showed variation in 13 amino acids in the Lac12p protein, rendering the protein non-functional for lactose transport. Genome analysis showed that the LAC12 gene is present in four copies in the subtelomeric regions of three different chromosomes but only the ancestral LAC12 gene encodes a functional lactose transporter. Other copies of LAC12 may be non-functional or have alternative substrates. The analysis raises some interesting questions regarding the evolution of sugar transporters in K. marxianus. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. Optical and magneto-optical properties of the endohedral La@C82 crystal

    Science.gov (United States)

    Rostampour, E.; Koohi, A.; Cyrousnezhad, F.

    2013-02-01

    The magneto-optical properties of solids are theoretically described by the circular dichroism (CD) and birefringence coefficient (θ). Using the Su-Schrieffer-Heeger (SSH) model in conjunction with the local field method, the optical dielectric tensor, CD and θ of the simple cubic phase of the La@C82 and C82 crystals are calculated. The results obtained from the La@C82 and C82 crystals are compared with those of the C70 and C60 crystals. It is shown that La@C82 has a richer optical spectrum than C82, C70 and C60. In the La@C82 crystal, absorption bands are shown by spectrum in the 0.58 to 7.0 eV region with sharp structures in each band which indicate the localized molecular structure coupled with long-range crystalline order. Results show that the circular dichroism and birefringence coefficient of the La@C82 crystal due to a single spin localized on the C82 cage are very larger than those of the C60, C70 and C82 crystals. Also, results show that the circular dichroism and birefringence coefficient of the C82 crystal are similar to those of the C60 and C70 crystals.

  11. Photohadronic origin of $\\gamma$-ray BL Lac emission: implications for IceCube neutrinos

    CERN Document Server

    Petropoulou, Maria; Padovani, Paolo; Mastichiadis, Apostolos; Resconi, Elisa

    2015-01-01

    The recent IceCube discovery of 0.1-1 PeV neutrinos of astrophysical origin opens up a new era for high-energy astrophysics. Although there are various astrophysical candidate sources, a firm association of the detected neutrinos with one (or more) of them is still lacking. A recent analysis of plausible astrophysical counterparts within the error circles of IceCube events showed that likely counterparts for nine of the IceCube neutrinos include mostly BL Lacs, among which Mrk 421. Motivated by this result and a previous independent analysis on the neutrino emission from Mrk 421, we test the BL Lac-neutrino connection in the context of a specific theoretical model for BL Lac emission. We model the spectral energy distribution (SED) of the BL Lacs selected as counterparts of the IceCube neutrinos using a one-zone leptohadronic model and mostly nearly simultaneous data. The neutrino flux for each BL Lac is self-consistently calculated, using photon and proton distributions specifically derived for every individ...

  12. Distinction of Indian commercial lac insect lines of Kerria spp. (Homoptera: Coccoidea) based on their morphometrics.

    Science.gov (United States)

    Ahmad, Ayashaa; Ramani, Ranganathan; Sharma, Kewal K; Vidyarthi, Ambrish S; Ramamurthy, Vilayanoor V

    2014-01-01

    The lac insects belong to the genus Kerria (Hemiptera: Coccoidea: Kerriidae) and are commercially exploited worldwide for the production of lac, which comes from their waxy test and has diverse industrial applications. The insects are maintained by the Indian Institute of Natural Resins and Gums as distinctive lines that are cultivated and commercialized in the lac producing areas of India. The lines are all considered to belong to the genus Kerria but without validation of their taxonomic characters, and their identity to species has not been ascertained. This study used single-factor analysis of variance and several multivariate analyses, such as principal component analysis, discriminant function analysis, and canonical discriminant analysis to explore the morphometrics of some of the adult female lac insect lines. The results have enabled the identification of some taxonomically significant characters in adult females, which has grouped the 32 lac insect lines studied into 15 species along with validation of the most significant characters. Distinctive grouping patterns for the species of Kerria have been brought out using morphometrics.

  13. Solving a discrete model of the lac operon using Z3

    Science.gov (United States)

    Gutierrez, Natalia A.

    2014-05-01

    A discrete model for the Lcac Operon is solved using the SMT-solver Z3. Traditionally the Lac Operon is formulated in a continuous math model. This model is a system of ordinary differential equations. Here, it was considerated as a discrete model, based on a Boolean red. The biological problem of Lac Operon is enunciated as a problem of Boolean satisfiability, and it is solved using an STM-solver named Z3. Z3 is a powerful solver that allows understanding the basic dynamic of the Lac Operon in an easier and more efficient way. The multi-stability of the Lac Operon can be easily computed with Z3. The code that solves the Boolean red can be written in Python language or SMT-Lib language. Both languages were used in local version of the program as online version of Z3. For future investigations it is proposed to solve the Boolean red of Lac Operon using others SMT-solvers as cvc4, alt-ergo, mathsat and yices.

  14. Relativistic Beaming and Orientation Effects in BL Lacertae Objects

    Indian Academy of Sciences (India)

    F. C. Odo; A. A. Ubachukwu; A. E. Chukwude

    2012-09-01

    We use the correlation between the core-to-lobe radio luminosity ratio () and the linear size () of a sample of BL Lacertae objects to investigate the relativistic beaming and radio source orientation paradigm for high peaked and low-peaked BL Lacs (X-ray and radio selected BL Lacs respectively) and to constrain relativistic beaming model for this extreme class of active galactic nuclei. We show that the - distributions of the BL Lac populations contradict blazar orientation sequence, with the X-ray selected BL Lacs (XBLs) being more consistent with the beaming and orientation model. On the premise that Fanaroff-Riley Type I radio galaxies are the unbeamed parent population of these objects, we derive the bulk Lorentz factor of the jets, ∼ 7-20 corresponding to a critical cone angle for optimum boosting, c of ∼ 1° - 4°, while on average, these objects are inclined at 5° - 12° to the line-of-sight. The implications of these results for the blazar unification sequence are discussed.

  15. Lac repressor: Crystallization of intact tetramer and its complexes with inducer and operator DNA

    Energy Technology Data Exchange (ETDEWEB)

    Pace, H.C.; Lu, P. (Univ. of Pennsylvania, Philadelphia (USA)); Lewis, M. (Univ. of Pennsylvania, Philadelphia, (USA) Smith Kline and French Labs., King of Prussia, PA (USA))

    1990-03-01

    The intact lac repressor tetramer, which regulates expression of the lac operon in Escherichia coli, has been crystallized in the native form, with an inducer, and in a ternary complex with operator DNA and an anti-inducer. The crystals without DNA diffract to better than 3.5 {angstrom}. They belong to the monoclinic space group C2 and have cell dimensions a = 164.7 {angstrom}, b = 75.6 {angstrom}, and c = 161.2 {angstrom}, with {alpha} = {gamma} = 90{degree} and {beta} = 125.5{degree}. Cocrystals have been obtained with a number of different lac operator-related DNA fragments. The complex with a blunt-ended 16-base-pair strand yielded tetragonal bipyramids that diffract to 6.5 {angstrom}. These protein-DNA cocrystals crack upon exposure to the gratuitous inducer isopropyl {beta}-D-thiogalactoside, suggesting a conformational change in the repressor-operator complex.

  16. The Lack of Torus Emission from BL Lacertae Objects: An Infrared View of Unification with WISE

    CERN Document Server

    Plotkin, Richard M; Brandt, W N; Markoff, Sera; Shemmer, Ohad; Wu, Jianfeng

    2011-01-01

    We use data from the Wide-Field Infrared Survey Explorer (WISE) to perform a statistical study on the mid-infrared (IR) properties of a large number ($\\sim10^2$) of BL Lac objects --- low-luminosity Active Galactic Nuclei (AGN) with a jet beamed toward the Earth. As expected, many BL Lac objects are so highly beamed that their jet synchrotron emission dominates their IR spectral energy distributions. In other BL Lac objects, however, the jet is not strong enough to completely dilute the rest of the AGN emission. We do not see observational signatures of the dusty torus from these weakly beamed BL Lac objects. The lack of observable torus emission is consistent with suggestions that BL Lac objects are fed by radiatively inefficient accretion disks. Implications for the "nature vs. nurture" debate for FR I and FR II radio galaxies are briefly discussed. Our study supports the notion that, beyond orientation, accretion rate plays an important role in AGN unification.

  17. Object and Objective Lost?

    DEFF Research Database (Denmark)

    Lopdrup-Hjorth, Thomas

    2015-01-01

    This paper explores the erosion and problematization of ‘the organization’ as a demarcated entity. Utilizing Foucault's reflections on ‘state-phobia’ as a source of inspiration, I show how an organization-phobia has gained a hold within Organization Theory (OT). By attending to the history...... of this organization-phobia, the paper argues that OT has become increasingly incapable of speaking about its core object. I show how organizations went from being conceptualized as entities of major importance to becoming theoretically deconstructed and associated with all kinds of ills. Through this history......, organizations as distinct entities have been rendered so problematic that they have gradually come to be removed from the center of OT. The costs of this have been rather significant. Besides undermining the grounds that gave OT intellectual credibility and legitimacy to begin with, the organization-phobia...

  18. STRUCTURAL ASPECTS REGARDING TO THE IMAGE OF ICE HOTEL BALEA LAC BREND

    Directory of Open Access Journals (Sweden)

    Marian ZAHARIA

    2008-06-01

    Full Text Available Applying a poll-based survey provides important information regarding the tourist offer particulars in Bâlea Lac area. On the day the survey is performed its main advantage is also outlined: the fact that this information display a good accuracy, are obtained in a short time span and involving relatively low expenses. Data collection and centralization of the answers provided by interviewed tourists regarding tourism practice in the Bâlea Lac area have led to drawing up distributions that are presented in the paper. Based on the respective information, statistics methods adequate to the study of tourist opinion on the Bâlea Lac Ice Hotel brand image. Several issues have been outlined, regarding the types of respondents based on their category, Romanian or foreigners, from Romania and based on destination countries, function of: the type of stay; the means of information; their answers referring to their first arrival at Bâlea Lac; the degree of destination assessment; their opinion on host reception; their preference for Bâlea Lac; appreciating value for money; age groups; gender; social and professional standing. The image created through the attractions and services provided in the Bâlea Lac tourist area by tourism activities closely related to the Ice Hotel is well appreciated, so that they have opened up a rather favourable expectancy for those willing to come back and for those tempted to try and spend their holidays in the presented hotel.

  19. Test of models of the cosmic infrared background with multiwavelength observations of the blazar 1ES 1218+30.4 in 2009

    Energy Technology Data Exchange (ETDEWEB)

    Archambault, S. [Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada); Arlen, T.; Aune, T. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Beilicke, M.; Buckley, J. H.; Bugaev, V.; Dickherber, R. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Benbow, W. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Bird, R.; Collins-Hughes, E. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Böttcher, M. [Department of Physics and Astronomy, Ohio University, Clippinger 339, Athens, OH 45701-2979 (United States); Bouvier, A. [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Connolly, M. P. [School of Physics, National University of Ireland Galway, University Road, Galway (Ireland); Cui, W.; Feng, Q. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Dumm, J. [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Errando, M. [Department of Physics and Astronomy, Barnard College, Columbia University, New York, NY 10027 (United States); Falcone, A. [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Federici, S., E-mail: krawcz@wuphys.wustl.edu [DESY, Platanenallee 6, D-15738 Zeuthen (Germany); and others

    2014-06-20

    We present the results of a multi-wavelength campaign targeting the blazar 1ES 1218+30.4 with observations with the 1.3 m McGraw-Hill optical telescope, the Rossi X-ray Timing Explorer (RXTE), the Fermi Gamma-Ray Space Telescope, and the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The RXTE and VERITAS observations were spread over a 13 day period and revealed clear evidence for flux variability, and a strong X-ray and γ-ray flare on 2009 February 26 (MJD 54888). The campaign delivered a well-sampled broadband energy spectrum with simultaneous RXTE and VERITAS very high energy (VHE, >100 GeV) observations, as well as contemporaneous optical and Fermi observations. The 1ES 1218+30.4 broadband energy spectrum—the first with simultaneous X-ray and VHE γ-ray energy spectra—is of particular interest as the source is located at a high cosmological redshift for a VHE source (z = 0.182), leading to strong absorption of VHE gamma rays by photons from the optical/infrared extragalactic background light (EBL) via γ{sub VHE} + γ{sub EBL} → e {sup +} e {sup –} pair-creation processes. We model the data with a one-zone synchrotron self-Compton (SSC) emission model and with the extragalactic absorption predicted by several recent EBL models. We find that the observations are consistent with the SSC scenario and all the EBL models considered in this work. We discuss observational and theoretical avenues to improve on the EBL constraints.

  20. Accumulation and therapeutic modulation of 6-sulfo LacNAc+ dendritic cells in multiple sclerosis

    Science.gov (United States)

    Thomas, Katja; Dietze, Kristin; Wehner, Rebekka; Metz, Imke; Tumani, Hayrettin; Schultheiß, Thorsten; Günther, Claudia; Schäkel, Knut; Reichmann, Heinz; Brück, Wolfgang; Schmitz, Marc

    2014-01-01

    Objective: To examine the potential role of 6-sulfo LacNAc+ (slan) dendritic cells (DCs) displaying pronounced proinflammatory properties in the pathogenesis of multiple sclerosis (MS). Methods: We determined the presence of slanDCs in demyelinated brain lesions and CSF samples of patients with MS. In addition, we explored the impact of methylprednisolone, interferon-β, glatiramer acetate, or natalizumab on the frequency of blood-circulating slanDCs in patients with MS. We also evaluated whether interferon-β modulates important proinflammatory capabilities of slanDCs. Results: SlanDCs accumulate in highly inflammatory brain lesions and are present in the majority of CSF samples of patients with MS. Short-term methylprednisolone administration reduces the percentage of slanDCs in blood of patients with MS and the proportion of tumor necrosis factor-α– or CD150-expressing slanDCs. Long-term interferon-β treatment decreases the percentage of blood-circulating slanDCs in contrast to glatiramer acetate or natalizumab. Furthermore, interferon-β inhibits the secretion of proinflammatory cytokines by slanDCs and their capacity to promote proliferation and differentiation of T cells. Conclusion: Accumulation of slanDCs in highly inflammatory brain lesions and their presence in CSF indicate that slanDCs may play an important role in the immunopathogenesis of MS. The reduction of blood-circulating slanDCs and the inhibition of their proinflammatory properties by methylprednisolone and interferon-β may contribute to the therapeutic efficiency of these drugs in patients with MS. PMID:25340085

  1. The Periplasmic Cavity of LacY Mutant Cys154→Gly : How Open Is Open?

    NARCIS (Netherlands)

    Jiang, Xiaoxu; Driessen, Arnold J.M.; Feringa, Ben L.; Kaback, H. Ronald

    2013-01-01

    The lactose permease from Escherichia coli (LacY) is a galactoside/H+ symporter that catalyzes the coupled stoichiometric transport of a sugar and an H+ across the cytoplasmic membrane. X-ray crystal structures of WT LacY and the conformationally restricted mutant Cys154→Gly exhibit an inward-facing

  2. Injectable hyaluronic acid/PEG-p(HPMAm-lac)-based hydrogels dually cross-linked by thermal gelling and Michael addition

    NARCIS (Netherlands)

    Dubbini, Alessandra; Censi, Roberta; Butini, Maria Eugenia; Sabbieti, Maria Giovanna; Agas, Dimitrios; Vermonden, Tina; Di Martino, Piera

    2015-01-01

    Fast in situ forming thermosensitive hydrogels consisted of vinyl sulfone bearing p(HPMAm-lac(1-2))-PEG-p(HPMAm-lac(1-2)) triblock copolymers and thiol modified hyaluronic acid were prepared via a dual cross-linking strategy based on thermal gelation at 37 degrees C and simultaneous Michael addition

  3. Program Evaluation: Outcomes of Participation in Lac Du Bois, the French Language Village of Concordia Language Villages

    Science.gov (United States)

    Clementi, Donna L.

    2012-01-01

    The purpose of this study was to describe perceptions of stakeholders (leadership of Concordia Language Villages, staff members and villagers of "Lac du Bois", the French Language Village of Concordia Language Villages), related to achievement of the mission statement. The research question was: How do stakeholders in "Lac du…

  4. Synthesis of tetravalent LacNAc-glycoclusters as high-affinity cross-linker against Erythrina cristagalli agglutinin.

    Science.gov (United States)

    Ogata, Makoto; Chuma, Yasushi; Yasumoto, Yoshinori; Onoda, Takashi; Umemura, Myco; Usui, Taichi; Park, Enoch Y

    2016-01-01

    Four kinds of tetravalent double-headed glycoclusters [(LacNAc)4-DHGs] were designed with linkers of varying lengths consisting of alkanedioic carboxyamido groups (C6, C12, C18 and C24) between two bi-antennary LacNAc-glycosides. These glycoclusters served as high-affinity cross-linking ligands for the LacNAc-binding lectin Erythrina cristagalli agglutinin (ECA). The binding activity and cross-linking between each ligand and ECA were characterized by a hemagglutination inhibition (HI) assay, isothermal titration calorimetry (ITC), a quantitative precipitation assay and dynamic light scattering (DLS). For the precipitation assay and DLS measurement, the synthesized (LacNAc)4-DHGs were found to be capable of binding and precipitating the ECA as multivalent ligands. ITC analysis indicated the binding of (LacNAc)4-DHGs was driven by a favorable enthalpy change. Furthermore, the entropy penalty from binding (LacNAc)4-DHGs clearly decreased in a spacer length-dependent manner. The binding affinities of flexible (LacNAc)4-DHGs (C18 and C24) with long spacers were found to be more favorable than those of the clusters having short spacers (C6 and C12). These results were supported by molecular dynamics simulations with explicit water molecules for the tetravalent glycoclusters with ECA. We concluded that the subtle modification in the epitope-presenting scaffolds exerts the significant effect in the recognition efficiency involved in the LacNAc moieties by ECA.

  5. A ubiquitous absorption feature in the X-ray spectra of BL Lacertae objects

    Science.gov (United States)

    Madejski, Greg M.; Mushotzky, Richard F.; Weaver, Kimberly A.; Arnaud, Keith A.; Urry, C. Megan

    1991-01-01

    The paper presents the broadband (0.5-20-keV) X-ray spectra of five X-ray bright BL Lac objects observed with the Einstein Observatory Solid State Spectrometer (SSS) and Monitor Proportional Counter (MPC) detectors. The combination of moderate energy resolution and broad spectral coverage makes it possible to confirm the presence of an absorption feature at an energy of 650 eV in the BL Lac object PKS 2155-304, originally reported by Canizares and Kruper (1984) based on higher resolution Einstein Objective Grating Spectrometer (OGS) data.

  6. AQP4 expression and its correlation with the Lac and NAA using proton magnetic resonance spectroscopy after rat cerebral ischemia

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ren-lan; XIE Peng

    2006-01-01

    Objective: To determine whether AQP4 expression is associated with lactate (Lac) and Nacetyl aspartate (NAA) and with apparent diffusion coefficient (ADC) abnormality after rat cerebral ischemia. Methods: The time courses of ADC and lactate and NAA assessed by proton magnetic resonance spectroscopy (1HMRS) were investigated at the time point of 6 h, and 1, 3, 7 d after rat cerebral ischemia induced by middle cerebral artery occlusion. Expression of AQP4 mRNA and protein were measured using RT-PCR and Western blot analysis respectively. Results: Significant reductions of NAA concentration and increases of lactate concentration were found after rat cerebral ischemia. The expressions of AQP4 mRNA and protein were increased at 6 h, and reached the peak at 1-3 d, then began to decrease at 7 d after rat cerebral ischemia. The expression of AQP4 was significantly correlated with NAA (rRT =-0.856, rw =-0. 927, P<0. 01), and with lactate (rW=0. 473, rRT=0. 413, P<0. 05), and with ADC values during the period of 1-7 d after rat cerebral ischemia (rW=0. 984, rRT= -0. 925, P<0.05). In addition, correlations between Lac and the ADC values(r=-0. 677, P<0. 05)and between NAA and ADC values during the period of 1-7 d after rat cerebral ischemia (r= 0. 909, P<0.05) were also observed. Conclusion: The data suggest that AQP4 is involved in the transport of water when brain edema is formed and cell membrane integrity is lost.

  7. SPECTROSCOPY OF THE LARGEST EVER {gamma}-RAY-SELECTED BL LAC SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, Michael S.; Romani, Roger W.; Healey, Stephen E.; Michelson, Peter F. [Department of Physics/KIPAC, Stanford University, Stanford, CA 94305 (United States); Cotter, Garret; Potter, William J. [Department of Astrophysics, University of Oxford, Oxford OX1 3RH (United Kingdom); Readhead, Anthony C. S.; Richards, Joseph L.; Max-Moerbeck, Walter; King, Oliver G. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)

    2013-02-20

    We report on spectroscopic observations covering most of the 475 BL Lacs in the second Fermi Large Area Telescope (LAT) catalog of active galactic nuclei (AGNs). Including archival measurements (correcting several erroneous literature values) we now have spectroscopic redshifts for 44% of the BL Lacs. We establish firm lower redshift limits via intervening absorption systems and statistical lower limits via searches for host galaxies for an additional 51% of the sample leaving only 5% of the BL Lacs unconstrained. The new redshifts raise the median spectroscopic z-tilde from 0.23 to 0.33 and include redshifts as large as z = 2.471. Spectroscopic redshift minima from intervening absorbers have z-tilde = 0.70, showing a substantial fraction at large z and arguing against strong negative evolution. We find that detected BL Lac hosts are bright ellipticals with black hole masses M {sub .} {approx} 10{sup 8.5} - 10{sup 9}, substantially larger than the mean of optical AGNs and LAT Flat Spectrum Radio Quasar samples. A slow increase in M {sub .} with z may be due to selection bias. We find that the power-law dominance of the optical spectrum extends to extreme values, but this does not strongly correlate with the {gamma}-ray properties, suggesting that strong beaming is the primary cause of the range in continuum dominance.

  8. Spectroscopy of the Largest Ever γ-Ray-selected BL Lac Sample

    Science.gov (United States)

    Shaw, Michael S.; Romani, Roger W.; Cotter, Garret; Healey, Stephen E.; Michelson, Peter F.; Readhead, Anthony C. S.; Richards, Joseph L.; Max-Moerbeck, Walter; King, Oliver G.; Potter, William J.

    2013-02-01

    We report on spectroscopic observations covering most of the 475 BL Lacs in the second Fermi Large Area Telescope (LAT) catalog of active galactic nuclei (AGNs). Including archival measurements (correcting several erroneous literature values) we now have spectroscopic redshifts for 44% of the BL Lacs. We establish firm lower redshift limits via intervening absorption systems and statistical lower limits via searches for host galaxies for an additional 51% of the sample leaving only 5% of the BL Lacs unconstrained. The new redshifts raise the median spectroscopic \\tilde{z} from 0.23 to 0.33 and include redshifts as large as z = 2.471. Spectroscopic redshift minima from intervening absorbers have \\tilde{z}= 0.70, showing a substantial fraction at large z and arguing against strong negative evolution. We find that detected BL Lac hosts are bright ellipticals with black hole masses M • ~ 108.5 - 109, substantially larger than the mean of optical AGNs and LAT Flat Spectrum Radio Quasar samples. A slow increase in M • with z may be due to selection bias. We find that the power-law dominance of the optical spectrum extends to extreme values, but this does not strongly correlate with the γ-ray properties, suggesting that strong beaming is the primary cause of the range in continuum dominance.

  9. 77 FR 27245 - Big Stone National Wildlife Refuge, Big Stone and Lac Qui Parle Counties, MN

    Science.gov (United States)

    2012-05-09

    ... Fish and Wildlife Service Big Stone National Wildlife Refuge, Big Stone and Lac Qui Parle Counties, MN... comprehensive conservation plan (CCP) and environmental assessment (EA) for Big Stone National Wildlife Refuge...: r3planning@fws.gov . Include ``Big Stone Draft CCP/ EA'' in the subject line of the message. Fax:...

  10. The Lac-Croche plutonic complex, Quebec: basement of Grenville paragneisses?

    NARCIS (Netherlands)

    Schrijver, K.

    1969-01-01

    A concordant body of presumably igneous, but deformed and at least partly recrystallized rocks, the Lac-Croche Plutonic Complex, consists of leuconoritic and mangeritic gneisses, and of monzonitic and granitic rocks. It is surrounded by gneisses, at least partly of sedimentary origin. Inclusions of

  11. Caractérisation des sables et morphologie du fond du lac du ...

    African Journals Online (AJOL)

    Administrateur

    Map of this lake 26 years after its setting in water. Key words : Dam .... La méthode d'interpolation retenue est l'IDW (Inverse Distance Weighting) avec un pas .... Figure 2 : Répartition des faciès de surface des sédiments du lac de Taabo. 3.3.

  12. Baseline survey of anthropogenic pressures for the Lac Bay ecosystem, Bonaire

    NARCIS (Netherlands)

    Debrot, A.O.

    2012-01-01

    Lac Bay of Bonaire is a shallow non-estuarine lagoon of about 700 hectares, separated from the open sea by a shallow coral barrier-reef. It possesses the only major concentration of seagrass beds and mangroves of the island. It is a designated Ramsar wetland of international significance, an

  13. Deterministic and stochastic population-level simulations of an artificial lac operon genetic network

    Directory of Open Access Journals (Sweden)

    Zygourakis Kyriacos

    2011-07-01

    Full Text Available Abstract Background The lac operon genetic switch is considered as a paradigm of genetic regulation. This system has a positive feedback loop due to the LacY permease boosting its own production by the facilitated transport of inducer into the cell and the subsequent de-repression of the lac operon genes. Previously, we have investigated the effect of stochasticity in an artificial lac operon network at the single cell level by comparing corresponding deterministic and stochastic kinetic models. Results This work focuses on the dynamics of cell populations by incorporating the above kinetic scheme into two Monte Carlo (MC simulation frameworks. The first MC framework assumes stochastic reaction occurrence, accounts for stochastic DNA duplication, division and partitioning and tracks all daughter cells to obtain the statistics of the entire cell population. In order to better understand how stochastic effects shape cell population distributions, we develop a second framework that assumes deterministic reaction dynamics. By comparing the predictions of the two frameworks, we conclude that stochasticity can create or destroy bimodality, and may enhance phenotypic heterogeneity. Conclusions Our results show how various sources of stochasticity act in synergy with the positive feedback architecture, thereby shaping the behavior at the cell population level. Further, the insights obtained from the present study allow us to construct simpler and less computationally intensive models that can closely approximate the dynamics of heterogeneous cell populations.

  14. SSC Model Fits to Simultaneous Fermi and CAO observations of Bl Lac's

    Science.gov (United States)

    Gordon, Tyler; Macomb, Daryl J.; Hand, Jared; Norris, Jay P.; Long, Min

    2016-01-01

    The Challis Astronomical Observatory (CAO) has been surveying a sample of blazar-type AGN since 2010. The CAO blazar sample includes4 3 sources - comprising 30 FSRQs, 15 BL Lacs, one radio galaxy and four unclassified sources - covering a redshift range 0.02 Potter and Cotter (MNRAS, 2012, 423, 756-765).

  15. Dct::lacZ ES cells: a novel cellular model to study melanocyte determination and differentiation.

    Science.gov (United States)

    Pla, Patrick; Solov'eva, Olga; Moore, Robert; Alberti, Christophe; Kunisada, Takahiro; Larue, Lionel

    2004-04-01

    Embryonic stem (ES) cells differentiate into various cell lineages in vitro. A procedure was previously designed to promote the differentiation of ES cells towards the melanocyte lineage and to obtain large and reproducible amounts of melanocytes. To elucidate the main events that lead to the development of melanocytes in vitro, we used transgenic Dct::lacZ mouse blastocysts to establish ES cell lines expressing the lacZ reporter gene under the control of the Dct promoter. Dct, a melanoblast marker, is expressed just after melanoblast determination in vivo. We evaluated the importance of recruitment, proliferation and differentiation during melanocyte ontogeny after the in vitro differentiation of Dct::lacZ ES cells into melanocytes. We showed that bFGF and cholera toxin induce precocious melanoblast determination, associated with early melanocyte differentiation. Edn3 induced melanoblast proliferation and long-term melanoblast recruitment, but not precocious determination. The lack of basic Fibroblast Growth Factor (bFGF) and cholera toxin can be partially compensated by Edn3. Thus, Dct::lacZ ES cells can be used as a model to study determination, proliferation and differentiation in the melanocyte lineage in vitro.

  16. Eutrophication status of Lac, Bonaire, Dutch Caribbean Including propolsals for measures

    NARCIS (Netherlands)

    Slijkerman, D.M.E.; Peachey, R.B.J.; Hausmann, P.S.; Meesters, H.W.G.

    2011-01-01

    Lac is a semi-enclosed lagoon located on the south-eastern side of Bonaire, and contains a diversity of shallow water coral reef associated habitats in close proximity such as mangroves, seagrass beds, Halimeda algal beds, the back reef and sand flats. These habitats support a diversity of fish and

  17. The Lac-Croche plutonic complex, Quebec: basement of Grenville paragneisses?

    NARCIS (Netherlands)

    Schrijver, K.

    1969-01-01

    A concordant body of presumably igneous, but deformed and at least partly recrystallized rocks, the Lac-Croche Plutonic Complex, consists of leuconoritic and mangeritic gneisses, and of monzonitic and granitic rocks. It is surrounded by gneisses, at least partly of sedimentary origin. Inclusions of

  18. 78 FR 48224 - Lac-Mégantic Railroad Accident Discussion and DOT Safety Recommendations

    Science.gov (United States)

    2013-08-07

    .... 13-13] Lac-M[eacute]gantic Railroad Accident Discussion and DOT Safety Recommendations AGENCY... their destinations safely and without incident. In calendar year 2011, for example, out of the... might also travel. Human Factors Finally, Transport Canada's emergency directive and order...

  19. Elastic Rod Model of a DNA Loop in the Lac Operon

    Science.gov (United States)

    Balaeff, Alexander; Mahadevan, L.; Schulten, Klaus

    1999-12-01

    We use the theory of elasticity to compute the shape of the DNA loop bridging the gap in the crystal structure of the lac repressor-DNA complex. The Kirchhoff system of equations with boundary conditions derived from the crystal structure is solved using a continuation method. This approach can be applied effectively to find coarse-grained conformational minima of DNA loops.

  20. Herziening LAC-signaalwaarden: op weg naar bodem-specifieke normen?

    NARCIS (Netherlands)

    Römkens, P.F.A.M.; Vries, de W.

    2001-01-01

    De huidige LAC-signaalwaarden voor bodemkwaliteit (gehalten aan schadelijke stoffen in de bodem waarbij normen voor gewaskwaliteit worden overschreden) zijn slechts beperkt geschikt voor een locatie-specifieke risico-inschatting m.b.t. zware metalen en arseen. Een overzicht en evaluatie van gebruikt

  1. Multiple Lac-mediated loops revealed by Bayesian statistics and tethered particle motion

    CERN Document Server

    Johnson, Stephanie; Phillips, Rob; Wiggins, Chris H; Lindén, Martin

    2014-01-01

    The bacterial transcription factor LacI loops DNA by binding to two separate locations on the DNA simultaneously. Despite being one of the best-studied model systems for transcriptional regulation, the number and conformations of loop structures accessible to LacI remain unclear, though the importance of multiple co-existing loops has been implicated in interactions between LacI and other cellular regulators of gene expression. To probe this issue, we have developed a new analysis method for tethered particle motion (TPM), a versatile and commonly-used in vitro single-molecule technique. Our method, vbTPM, is based on a variational Bayes treatment of hidden Markov models. It learns the number of distinct states (i.e., DNA-protein conformations) directly from TPM data with better resolution than existing methods, while easily correcting for common experimental artifacts. Studying short (roughly 100 bp) LacI-mediated loops, we are able to resolve three distinct loop structures, more than previously reported at ...

  2. Function, Structure, and Evolution of the Major Facilitator Superfamily: The LacY Manifesto

    Directory of Open Access Journals (Sweden)

    M. Gregor Madej

    2014-01-01

    Full Text Available The major facilitator superfamily (MFS is a diverse group of secondary transporters with members found in all kingdoms of life. A paradigm for MFS is the lactose permease (LacY of Escherichia coli, which couples the stoichiometric translocation of a galactopyranoside and an H+ across the cytoplasmic membrane. LacY has been the test bed for the development of many methods applied for the analysis of transport proteins. X-ray structures of an inward-facing conformation and the most recent structure of an almost occluded conformation confirm many conclusions from previous studies. Although structure models are critical, they are insufficient to explain the catalysis of transport. The clues to understanding transport are based on the principles of enzyme kinetics. Secondary transport is a dynamic process—static snapshots of X-ray crystallography describe it only partially. However, without structural information, the underlying chemistry is virtually impossible to conclude. A large body of biochemical/biophysical data derived from systematic studies of site-directed mutants in LacY suggests residues critically involved in the catalysis, and a working model for the symport mechanism that involves alternating access of the binding site is presented. The general concepts derived from the bacterial LacY are examined for their relevance to other MFS transporters.

  3. The mutation detection system of repackaged lambda phage containing LacZ gene

    Institute of Scientific and Technical Information of China (English)

    LiuY; CaoJ

    2002-01-01

    The mutation detection system of repackaged lambda phage has been constructed.the mutagen-treated lambda DNA with LacZ gene was repackaged in vitro and the packaged lambda phages were then grown in e.coli Y1090 on a selective plate containing x-gal and isopropylthio-β-D-galactoside.the survival and mutation frequency was determined by counting the clearplaque mutants,the molecular mutation mechanisms of 1-ethyl-1-nitrosourea(ENU) and 9-aminoacridine(9-AA) were further studied by extracting and sequencing the LacZ gene of the mutants.The results demonstrated that the mutation detection system of repackaged lambda gtll DNA containing LacZ gene was not only simple,cheap and timesaving,but also was high specific and high sensitive.Then it is possible for this system to be used as a preliminary mutation screening for chemicals by analyzing the survival of the packaged phages and the mutation frequency,and it's also possible used to analyze the molecular mutation mechanism be sequencing the partial or entire LacZ gene.

  4. Des Lacs National Wildlife Refuge annual habitat work plan 2005

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual habitat management plan outlines working habitat objectives for wetland habitats based on refuge purposes, professional judgment and experience for Des...

  5. Effects of Redshift on the Classifying Criteria of BL Lacertae Objects

    Institute of Scientific and Technical Information of China (English)

    Li Ma; Luo-En Chen; Guang-Zhong Xie; Ji-Yang Ren; Zhao-Hua Xie; Shu-Bai Zhou; Hui Wu; Dong-Cheng Mei

    2007-01-01

    We have collected a sample of 70 BL Lacs(33 radio-selected BL Lacs and 37 X-ray selected BL Lacs) with multi-waveband data for investigating the classifying criteria of BL Lacertae Objects.For each source,we estimate its luminosities in radio.optical and X-ray,the broad-band spectral index from radio to X-ray and the peak frequency of the synchrotron emission,and make a statistical analysis of the data obtained.Our main results are as follows:(1)The broad-band spectral index and the peak frequency have no correlation with the redshift.while they are inversely correlated with each other and they could be regarded as equivalent classifying criteria of BL Lac objects.(2)There are significant effects of the luminosity/redshift relation on the observed luminosity distribution in our sample,hence,if the radio luminosity is to be used as a classifying criterion of BL Lac objects.it should not be regarded as equivalent to the broad-band spectral index or the peak frequency.(3)Our results supply a specific piece of evidence for the suggestion that the use of luminosities always introduces a redshift bias to the data and show that the location of the peak frequency is not always linked to the luminosity of any wave band.

  6. The Contribution of Fermi-2LAC Blazars to Diffuse TeV–PeV Neutrino Flux

    Science.gov (United States)

    Aartsen, M. G.; Abraham, K.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Ahrens, M.; Altmann, D.; Andeen, K.; Anderson, T.; Ansseau, I.; Anton, G.; Archinger, M.; Arguelles, C.; Arlen, T. C.; Auffenberg, J.; Axani, S.; Bai, X.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Becker Tjus, J.; Becker, K.-H.; BenZvi, S.; Berghaus, P.; Berley, D.; Bernardini, E.; Bernhard, A.; Besson, D. Z.; Binder, G.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blot, S.; Boersma, D. J.; Bohm, C.; Börner, M.; Bos, F.; Bose, D.; Böser, S.; Botner, O.; Braun, J.; Brayeur, L.; Bretz, H.-P.; Burgman, A.; Casey, J.; Casier, M.; Cheung, E.; Chirkin, D.; Christov, A.; Clark, K.; Classen, L.; Coenders, S.; Collin, G. H.; Conrad, J. M.; Cowen, D. F.; Cruz Silva, A. H.; Daughhetee, J.; Davis, J. C.; Day, M.; de André, J. P. A. M.; De Clercq, C.; del Pino Rosendo, E.; Dembinski, H.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de Wasseige, G.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; di Lorenzo, V.; Dujmovic, H.; Dumm, J. P.; Dunkman, M.; Eberhardt, B.; Ehrhardt, T.; Eichmann, B.; Euler, S.; Evenson, P. A.; Fahey, S.; Fazely, A. R.; Feintzeig, J.; Felde, J.; Filimonov, K.; Finley, C.; Flis, S.; Fösig, C.-C.; Franckowiak, A.; Fuchs, T.; Gaisser, T. K.; Gaior, R.; Gallagher, J.; Gerhardt, L.; Ghorbani, K.; Giang, W.; Gladstone, L.; Glagla, M.; Glüsenkamp, T.; Goldschmidt, A.; Golup, G.; Gonzalez, J. G.; Góra, D.; Grant, D.; Griffith, Z.; Haack, C.; Haj Ismail, A.; Hallgren, A.; Halzen, F.; Hansen, E.; Hansmann, B.; Hansmann, T.; Hanson, K.; Hebecker, D.; Heereman, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hignight, J.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Holzapfel, K.; Homeier, A.; Hoshina, K.; Huang, F.; Huber, M.; Huelsnitz, W.; Hultqvist, K.; In, S.; Ishihara, A.; Jacobi, E.; Japaridze, G. S.; Jeong, M.; Jero, K.; Jones, B. J. P.; Jurkovic, M.; Kappes, A.; Karg, T.; Karle, A.; Katz, U.; Kauer, M.; Keivani, A.; Kelley, J. L.; Kemp, J.; Kheirandish, A.; Kim, M.; Kintscher, T.; Kiryluk, J.; Kittler, T.; Klein, S. R.; Kohnen, G.; Koirala, R.; Kolanoski, H.; Konietz, R.; Köpke, L.; Kopper, C.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Krings, K.; Kroll, M.; Krückl, G.; Krüger, C.; Kunnen, J.; Kunwar, S.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Lanfranchi, J. L.; Larson, M. J.; Lennarz, D.; Lesiak-Bzdak, M.; Leuermann, M.; Leuner, J.; Lu, L.; Lünemann, J.; Madsen, J.; Maggi, G.; Mahn, K. B. M.; Mancina, S.; Mandelartz, M.; Maruyama, R.; Mase, K.; Maunu, R.; McNally, F.; Meagher, K.; Medici, M.; Meier, M.; Meli, A.; Menne, T.; Merino, G.; Meures, T.; Miarecki, S.; Middell, E.; Mohrmann, L.; Montaruli, T.; Moulai, M.; Nahnhauer, R.; Naumann, U.; Neer, G.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke Pollmann, A.; Olivas, A.; Omairat, A.; O’Murchadha, A.; Palczewski, T.; Pandya, H.; Pankova, D. V.; Penek, Ö.; Pepper, J. A.; Pérez de los Heros, C.; Pfendner, C.; Pieloth, D.; Pinat, E.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Quinnan, M.; Raab, C.; Rädel, L.; Rameez, M.; Rawlins, K.; Reimann, R.; Relich, M.; Resconi, E.; Rhode, W.; Richman, M.; Riedel, B.; Robertson, S.; Rongen, M.; Rott, C.; Ruhe, T.; Ryckbosch, D.; Rysewyk, D.; Sabbatini, L.; Sanchez Herrera, S. E.; Sandrock, A.; Sandroos, J.; Sarkar, S.; Satalecka, K.; Schimp, M.; Schlunder, P.; Schmidt, T.; Schoenen, S.; Schöneberg, S.; Schönwald, A.; Schumacher, L.; Seckel, D.; Seunarine, S.; Soldin, D.; Song, M.; Spiczak, G. M.; Spiering, C.; Stahlberg, M.; Stamatikos, M.; Stanev, T.; Stasik, A.; Steuer, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Ström, R.; Strotjohann, N. L.; Sullivan, G. W.; Sutherland, M.; Taavola, H.; Taboada, I.; Tatar, J.; Ter-Antonyan, S.; Terliuk, A.; Tešić, G.; Tilav, S.; Toale, P. A.; Tobin, M. N.; Toscano, S.; Tosi, D.; Tselengidou, M.; Turcati, A.; Unger, E.; Usner, M.; Vallecorsa, S.; Vandenbroucke, J.; van Eijndhoven, N.; Vanheule, S.; van Rossem, M.; van Santen, J.; Veenkamp, J.; Vehring, M.; Voge, M.; Vraeghe, M.; Walck, C.; Wallace, A.; Wallraff, M.; Wandkowsky, N.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whelan, B. J.; Wickmann, S.; Wiebe, K.; Wiebusch, C. H.; Wille, L.; Williams, D. R.; Wills, L.; Wissing, H.; Wolf, M.; Wood, T. R.; Woolsey, E.; Woschnagg, K.; Xu, D. L.; Xu, X. W.; Xu, Y.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zoll, M.; IceCube Collaboration

    2017-01-01

    The recent discovery of a diffuse cosmic neutrino flux extending up to PeV energies raises the question of which astrophysical sources generate this signal. Blazars are one class of extragalactic sources which may produce such high-energy neutrinos. We present a likelihood analysis searching for cumulative neutrino emission from blazars in the 2nd Fermi-LAT AGN catalog (2LAC) using IceCube neutrino data set 2009-12, which was optimized for the detection of individual sources. In contrast to those in previous searches with IceCube, the populations investigated contain up to hundreds of sources, the largest one being the entire blazar sample in the 2LAC catalog. No significant excess is observed, and upper limits for the cumulative flux from these populations are obtained. These constrain the maximum contribution of 2LAC blazars to the observed astrophysical neutrino flux to 27% or less between around 10 TeV and 2 PeV, assuming the equipartition of flavors on Earth and a single power-law spectrum with a spectral index of ‑2.5. We can still exclude the fact that 2LAC blazars (and their subpopulations) emit more than 50% of the observed neutrinos up to a spectral index as hard as ‑2.2 in the same energy range. Our result takes into account the fact that the neutrino source count distribution is unknown, and it does not assume strict proportionality of the neutrino flux to the measured 2LAC γ-ray signal for each source. Additionally, we constrain recent models for neutrino emission by blazars.

  7. Spectrum of Very High Energy Gamma-Rays from the blazar 1ES1959+650 during Flaring Activity in 2002

    CERN Document Server

    Daniel, M K; Boyle, P J; Bradbury, S M; Buckley, J H; Carter-Lewis, D A; Celik, O; Cui, W; Dowdall, C; Duke, C; Fegan, D J; La Perez, I C; Fegan, S J; Finley, J P; Fortson, L F; Gaidos, J A; Gibbs, K; Gammell, S; Hall, J; Hall, T A; Hillas, A M; Holder, J; Horan, D; Jordan, M; Kertzman, M; Kieda, D; Kildea, J; Knapp, J; Kosack, K; Krawczynski, H; Krennrich, F; Le Bohec, S; Linton, E T; Lloyd-Evans, J; Moriarty, P; Müller, D; Nagai, T N; Ong, R A; Page, M; Pallassini, R; Petry, D; Power-Mooney, B; Quinn, J; Rebillot, P; Reynolds, P T; Rose, H J; Schroedter, M; Sembroski, G H; Swordy, S P; Vasilev, V V; Wakely, S P; Walker, G; Weekes, T C

    2005-01-01

    The blazar 1ES 1959+650 was observed in a flaring state with the Whipple 10 m Imaging Atmospheric Cherenkov Telescope during May of 2002. A spectral analysis has been carried out on the data from that time period and the resulting very high energy gamma-ray spectrum ($E \\geq 316$ GeV) can be well fit by a power-law of differential spectral index \\alpha = 2.78 +/- 0.12_{stat.} +/- 0.21_{sys.}. On June 4th 2002, the source flared dramatically in the gamma-ray range without any coincident increase in the X-ray emission, providing the first unambiguous example of an `orphan' gamma-ray flare from a blazar. The gamma-ray spectrum for these data can also be described by a simple power-law fit with \\alpha = 2.82 +/- 0.15_{stat.} +/- 0.30_{sys.}. There is no compelling evidence for spectral variability, or for any cut-off to the spectrum.

  8. Chandra View of the Warm-Hot IGM toward 1ES 1553+113: Absorption Line Detections and Identifications (Paper I)

    CERN Document Server

    Nicastro, F; Krongold, Y; Mathur, S; Gupta, A; Danforth, C; Barcons, X; Borgani, S; Branchini, E; Cen, R; Davé, R; Kaastra, J; Paerels, F; Piro, L; Shull, J M; Takei, Y; Zappacosta, L

    2012-01-01

    About 30-40 percent of the expected number of baryons is still missing in the local Universe (z \\lesssim 0.4). They are predicted to be hiding in a web of intergalactic gas at temperatures of about 10^5-10^7 K (the WHIM). Detecting this matter has had limited success so far, because of its low-density and high temperature, which makes it difficult to detect with current far-ultraviolet and X-ray instrumentation. Here we present the first results from our pilot 500 ks Chandra-LETG observation of the soft X-ray brightest source in the z > 0.4 sky, the blazar 1ES 1553+113. We identify a total of 11 possible absorption lines, with single-line statistical significances between 2.2-4.1 sigma. Six of these lines are detected at high significance (3.6 < \\sigma < 4.1), while the remaining five are regarded as marginal detections in association with either other X-ray lines detected at higher significance and/or FUV signposts. Three of these lines are consistent with metal absorption at z~0. The remaining 8 lines...

  9. On the relationship between BL Lacertae objects and radio galaxies

    CERN Document Server

    Landt, Hermine

    2008-01-01

    We present deep radio images at 1.4 GHz of a large and complete sample of BL Lacertae objects (BL Lacs) selected from the Deep X-ray Radio Blazar Survey (DXRBS). We have observed 24 northern sources with the Very Large Array (VLA) in both its A and C configurations and 15 southern sources with the Australia Telescope Compact Array (ATCA) in its largest configuration. We find that in the DXRBS, as in the 1-Jy survey, which has a radio flux limit roughly ten times higher than the DXRBS, a considerable number (about a third) of BL Lacs can be identified with the relativistically beamed counterparts of Fanaroff-Riley type II (FR II) radio galaxies. We attribute the existence of FR II-BL Lacs, which is not accounted for by current unified schemes, to an inconsistency in our classification scheme for radio-loud active galactic nuclei (AGN). Taking the extended radio power as a suitable measure of intrinsic jet power, we find similar average values for low- (LBL) and high-energy peaked BL Lacs (HBL), contrary to the...

  10. Enzymatic Synthesis of N-Acetyllactosamine (LacNAc Type 1 Oligomers and Characterization as Multivalent Galectin Ligands

    Directory of Open Access Journals (Sweden)

    Thomas Fischöder

    2017-08-01

    Full Text Available Repeats of the disaccharide unit N-acetyllactosamine (LacNAc occur as type 1 (Galβ1, 3GlcNAc and type 2 (Galβ1, 4GlcNAc glycosylation motifs on glycoproteins and glycolipids. The LacNAc motif acts as binding ligand for lectins and is involved in many biological recognition events. To the best of our knowledge, we present, for the first time, the synthesis of LacNAc type 1 oligomers using recombinant β1,3-galactosyltransferase from Escherichia coli and β1,3-N-acetylglucosaminyltranferase from Helicobacter pylori. Tetrasaccharide glycans presenting LacNAc type 1 repeats or LacNAc type 1 at the reducing or non-reducing end, respectively, were conjugated to bovine serum albumin as a protein scaffold by squarate linker chemistry. The resulting multivalent LacNAc type 1 presenting neo-glycoproteins were further studied for specific binding of the tumor-associated human galectin 3 (Gal-3 and its truncated counterpart Gal-3∆ in an enzyme-linked lectin assay (ELLA. We observed a significantly increased affinity of Gal-3∆ towards the multivalent neo-glycoprotein presenting LacNAc type 1 repeating units. This is the first evidence for differences in glycan selectivity of Gal-3∆ and Gal-3 and may be further utilized for tracing Gal-3∆ during tumor progression and therapy.

  11. Isolation and analysis of two Escherichia coli K-12 ilv attenuator deletion mutants with high-level constitutive expression of an ilv-lac fusion operon.

    OpenAIRE

    Bennett, D. C.; Umbarger, H E

    1984-01-01

    A lysogenizing lambda phage, lambda dilv-lac11, was constructed to carry an ilvD-lac operon fusion. Expression from the phage of the ilvE and lacZ genes is controlled by an intact ilv control region also carried by this phage. Two spontaneous mutants of lambda dilv-lac11 that have high-level constitutive expression of the ilv-lac fusion operon were isolated by growth on a beta-chloroalanine selective medium. The mutants were shown by nucleotide sequence determination to contain large deletion...

  12. Regulation of nitrogen fixation in Klebsiella pneumoniae: isolation and characterization of strains with nif-lac fusions.

    Science.gov (United States)

    MacNeil, D; Zhu, J; Brill, W J

    1981-01-01

    Strains with lac fused to each of the seven nif operons were isolated by two different methods. Repressing conditions prevented expression of all nif operons, whereas derepressing conditions led to the expression of all nif operons. No differences in Nif regulation were observed between Escherichia coli and Klebsiella pneumoniae with the same nif-lac fusions. Most derivatives of nif-lac fusion strains selected on lactose and NH4+ contained nif operator mutations. Some derivative contained deletions, which establishes that the direction of transcription of all seven nif operons is toward his

  13. Expression of the lacZ gene in Escherichia coli irradiated with gamma rays

    Directory of Open Access Journals (Sweden)

    Mikio Kato

    2014-10-01

    Full Text Available Exposure of bacterial cells to ionizing radiation damages cellular components and causes cell death. We examined the induction of the plasmid-encoded lacZ gene in Escherichia coli JM109 harboring pUC19 after irradiation with gamma rays. The data demonstrated that cells irradiated with 6 or 8 kGy gamma rays lost their ability to grow on nutrient agar plates, but retained the ability to induce lacZ gene expression by IPTG at about 10% the level of the nonirradiated control. Thus, inactivation of cells by irradiation may provide another option for establishing a vehicle of protein and DNA, as nonpropagating protein-producing apparatus, albeit with lower capacity than intact cells.

  14. Rice Lake National Wildlife Refuge and Mille Lacs National Wildlife Refuge: Comprehensive Conservation Plan and Environmental Assessment

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Comprehensive Conservation Plan (CCP) was written to guide management on Rice Lake and Mille Lacs NWRs for the next 15 years. This plan outlines the refuges'...

  15. Complete Genomes of Bacillus coagulans S-lac and Bacillus subtilis TO-A JPC, Two Phylogenetically Distinct Probiotics

    National Research Council Canada - National Science Library

    Khatri, Indu; Sharma, Shailza; Ramya, T N C; Subramanian, Srikrishna

    2016-01-01

    .... We report the complete genomes of two commercially available probiotics, Bacillus coagulans S-lac and Bacillus subtilis TO-A JPC, and compare them with the genomes of other Bacillus and Lactobacillus...

  16. Narrative report for May, June, July, August, 1945 Des Lacs National Wildlife Refuge & Easement Refuge in District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from May through August of 1945. The report begins by summarizing the...

  17. Narrative report for May, June, July and August 1944 Des Lacs National Wildlife Refuge & Easement Refuges in District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from May through August of 1944. The report begins by summarizing the...

  18. Rice Lake National Wildlife Refuge, Mille Lacs Refuge, Sandstone Unit [Narrative report]: July 1, 1974 to June 30, 1975

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Rice Lake NWR and Mille Lacs NWR outlines Refuge accomplishments during the 1975 fiscal year. The report begins by summarizing the...

  19. Archive of Geosample Data and Information from the University of Minnesota National Lacustrine Core Repository (LacCore)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The National Lacustrine Core Repository (LacCore), operated by the University of Minnesota is a partner in the Index to Marine and Lacustrine Geological Samples...

  20. Narrative report for September, October, November, December, 1945 Des Lacs National Wildlife Refuge and Easement Refuges in District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from September through December of 1945. The report begins by summarizing...

  1. Lac Qui Parle Flood Control Project Master Plan for Public Use Development and Resource Management.

    Science.gov (United States)

    1980-08-01

    lower 18 miles to the mouth, the fall is about 14.0 feet per mile. Tributaries entering from the north, such as the Pomme de Terre and Chippewa Rivers...rather poorly defined, with small lakes and marshy areas marking the watercourses. Between the Pom de Terre and Chippewa River mouths are some ancient...agricultural limitations. 3.13 Water Resources Surface Waters The dig Stone Lake, Po-me de Terre River, Yellow Bank River, Lac qui Parle River, and

  2. Development of Mammalian Cell Lines with lac Operator-Tagged Chromosomes

    OpenAIRE

    sprotocols

    2014-01-01

    Authors: Yuri G. Strukov and Andrew S. Belmont This protocol was adapted from “Development of Mammalian Cell Lines with lac Operator-Tagged Chromosomes,” Chapter 25, in[ *Live Cell Imaging* ](http://www.cshlpress.com/link/livecelp.htm)(eds. Goldman and Spector). Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, USA, 2005. ### INTRODUCTION The discovery and use of fluorescent proteins to label chromosomal proteins has yielded basic structural information as well as insig...

  3. Birth distribution in cystic fibrosis in Saguenay-Lac-St-Jean, Quebec, Canada.

    Science.gov (United States)

    Daigneault, J; Aubin, G; Simard, F; De Braekeleer, M

    1991-09-01

    Although a seasonal trend in the birth distribution has been reported in cystic fibrosis (CF), this finding is still very controversial. The birth distribution of 113 patients with cystic fibrosis born in Saguenay-Lac-St-Jean (complete ascertainment) was analysed using two different statistical methods. Our results showed no monthly or seasonal birth variation. It is likely that a bias owing to incomplete ascertainment might explain why some previous studies found a seasonal trend in the birth distribution of cystic fibrosis.

  4. Far Ultraviolet Spectroscopy of Old Novae. II. RR Pic, V533 Her, and DI Lac

    Science.gov (United States)

    Sion, Edward M.; Godon, Patrick; Jones, Liam

    2017-03-01

    The old novae V533 Her (Nova Her 1963), DI Lac (Nova Lac 1910), and RR Pic (Nova Pic 1891) are in (or near) their quiescent stage, following their nova explosions, and continue to accrete at a high rate in the aftermath of their explosions. They exhibit continua that are steeply rising into the FUV, as well as absorption lines and emission lines of uncertain origin. All three have Far Ultraviolet Spectroscopic Explorer (FUSE) spectra that offer not only higher spectral resolution but also wavelength coverage extending down to the Lyman Limit. For DI Lac, we have matched these FUSE spectra with existing archival International Ultraviolet Explorer spectral coverage to broaden the FUV wavelength coverage. We adopted the newly determined interstellar reddening corrections of Selvelli & Gilmozzi. The dereddened FUV spectra have been modeled with our grids of optically thick accretion disks and hot, NLTE white dwarf (WD) photospheres. The results of our modeling analysis indicate that the hot components in RR Pic and V533 Her are likely to be accretion disks with mass accretion rates of 10‑8 M ⊙ yr‑1 and 10‑9 M ⊙ yr‑1 respectively. However, the disk cannot produce the observed absorption lines. For the WD to be the source of the absorption lines in these two systems, it must be very hot, with a radius several times its expected size (because the WD in these systems is massive, it has a smaller radius). For DI Lac, we find the best fit to be a disk with \\dot{M}={10}-10 {M}ȯ {{yr}}-1 with a 30,000 K WD. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer (FUSE). FUSE was operated for NASA by the Johns Hopkins University under NASA contract NAS5-32985.

  5. The use of lacZ marker in enumeration of Azotobacter chroococcum in carrier based inoculants

    Directory of Open Access Journals (Sweden)

    Manu Solanki

    2014-06-01

    Full Text Available A transconjugant of Azotobacter chroococcum Mac 27 tagged with lac Z(A. chroococcum Mac27 L was found to possess high levels of β-galactosidase activity constitutively.Further, the lac Z marker was found to be stably integrated into the chromosome of the A. chroococcum Mac 27 and did not have any adverse effect on growth, nitrogen fixation and excretion of ammonia. A quick method to determine the viable cell number in broth culture and carrier based inoculants has been developed on the basis of β-galactosidase assay. It was found that there was a direct relationship between the number of cell as determined by standard plate count and intensity of colour that developed upon degradation of ONPG due to β-galactosidase activity .The method was found to be sensitive enough to determine 1.7 x 10(6 CFU mL-1 in broth culture as well as carrier based Azotobacter inoculants. Further, it was observed that when A. chroococcum Mac27 L was inoculated on Brassica campestris, it could be detected in the presence of other bacteria capable of growing on Burks agar medium containing X-gal on the basis of lac Z genetic marker.

  6. The variable V381 Lac and its possible connection with the R CrB phenomenon

    CERN Document Server

    Rossi, Corinne; Di Paola, Andrea; Gigoyan, Kamo S; Nesci, Roberto

    2015-01-01

    We have performed new medium resolution spectroscopy, optical and near infrared photometry to monitor the variability of the AGB carbon star V 381 Lac. Our observations revealed rapid and deep changes in the spectrum and extreme variability in the optical and near infrared bands. Most notably we observed the change of NaI D lines from deep absorption to emission, and the progressive growing of the [N II] doublet 6548-6584 A emission, strongly related to the simultaneous photometric fading. V381 Lac occupies regions of 2MASS and WISE colour-colour diagrams typical of stars with dust formation in the envelope. The general framework emerging from the observations of V381 Lac is that of a cool AGB carbon star undergoing episodes of high mass ejection and severe occultation of the stellar photosphere reminiscent of those characterising the RCB phenomenon. Comparing the Spectral Energy Distribution obtained with the theoretical model for AGB evolution with dust in the circumstellar envelope, we can identify V381 La...

  7. Why are some BL Lacs detected by \\fermi, but others not ?

    CERN Document Server

    Wu, Zhongzu; Gu, Minfeng; Chen, Liang

    2014-01-01

    By cross-correlating an archival sample of 170 BL Lacs with 2 year \\fermilat AGN sample, we have compiled a sample of 100 BL Lacs with \\fermi detection (FBLs), and a sample of 70 non-\\fermi BL Lacs (NFBLs). We compared various parameters of FBLs with those of NFBLs, including the redshift, the low frequency radio luminosity at 408 MHz ($L_{\\rm 408MHz}$), the absolute magnitude of host galaxies ($M_{\\rm host}$), the polarization fraction from NVSS survey ($P_{\\rm NVSS}$), the observed arcsecond scale radio core flux at 5 GHz ($F_{\\rm core}$) and jet Doppler factor; all the parameters are directly \\textbf{measured} or derived from available data from literatures. We found that the Doppler factor is on average larger in FBLs than in NFBLs, and the $Fermi~ \\gamma$-ray detection rate is higher in sources with higher Doppler factor. In contrast, there are no significant differences in terms of the intrinsic parameters of redshift, $ L_{\\rm 408MHz}$, $ M_{\\rm host}$ and $ P_{\\rm NVSS}$. FBLs seem to have a higher pr...

  8. A new photometric and spectroscopic study of the eclipsing binaries CC Her and CM Lac: Physical parameters and evolutionary status

    CERN Document Server

    Liakos, Alexios

    2014-01-01

    New complete light and radial velocities curves were obtained for the eclipsing binaries CC Her and CM Lac. The data are analysed with modern techniques in order to derive the physical parameters of the systems and study their present evolutionary status. We found that CC Her is a classical Algol type binary, while CM Lac is a detached system with two Main Sequence stars in asynchronous orbit.

  9. Object crowding.

    Science.gov (United States)

    Wallace, Julian M; Tjan, Bosco S

    2011-05-25

    Crowding occurs when stimuli in the peripheral fields become harder to identify when flanked by other items. This phenomenon has been demonstrated extensively with simple patterns (e.g., Gabors and letters). Here, we characterize crowding for everyday objects. We presented three-item arrays of objects and letters, arranged radially and tangentially in the lower visual field. Observers identified the central target, and we measured contrast energy thresholds as a function of target-to-flanker spacing. Object crowding was similar to letter crowding in spatial extent but was much weaker. The average elevation in threshold contrast energy was in the order of 1 log unit for objects as compared to 2 log units for letters and silhouette objects. Furthermore, we examined whether the exterior and interior features of an object are differentially affected by crowding. We used a circular aperture to present or exclude the object interior. Critical spacings for these aperture and "donut" objects were similar to those of intact objects. Taken together, these findings suggest that crowding between letters and objects are essentially due to the same mechanism, which affects equally the interior and exterior features of an object. However, for objects defined with varying shades of gray, it is much easier to overcome crowding by increasing contrast.

  10. Performance Objectives

    Science.gov (United States)

    1978-12-01

    objectives may direct students’ learning (Duchastel and Merrill, 1973; Kapfer , 1970; Kibler et al., 1974), since such objectives may provide...matter learning. Journal of Educational Psychology, 62(1): 67-70 (1971). Kapfer , P. G. Behavioral objectives and the curriculum processor. Educational

  11. Seven-Year Multi-Colour Optical Monitoring of BL Lacertae Object S5 0716+714

    Indian Academy of Sciences (India)

    Jianghua Wu; Yan Dai; Xu Zhou; Jun Ma

    2014-09-01

    We monitored the BL Lac object S5 0716+714 in five intermediate optical passbands from 2004 September to 2011 April. The object was active most of the time and intra-day variability was frequently observed. The total variation amplitude tended to decrease with decreasing frequency. Strong bluer-when-brighter chromatism was observed on both long and short timescales.

  12. Agile Objects

    Science.gov (United States)

    German, Senta; Harris, Jim

    2017-01-01

    In this article, the authors argue that the art-historical canon, however it is construed, has little relevance to the selection of objects for museum-based teaching. Their contention is that all objects are fundamentally agile and capable of interrogation from any number of disciplinary standpoints, and that the canon of museum education,…

  13. Glucose repression of lactose/galactose metabolism in Kluyveromyces lactis is determined by the concentration of the transcriptional activator LAC9 (K1GAL4) [corrected

    OpenAIRE

    Zachariae, W; Kuger, P; Breunig, K D

    1993-01-01

    In the budding yeast Kluyveromyces lactis glucose repression of genes involved in lactose and galactose metabolism is primarily mediated by LAC9 (or K1GAL4) the homologue of the well-known Saccharomyces cerevisiae transcriptional activator GAL4. Phenotypic difference in glucose repression existing between natural strains are due to differences in the LAC9 gene (Breunig, 1989, Mol.Gen.Genet. 261, 422-427). Comparison between the LAC9 alleles of repressible and non-repressible strains revealed ...

  14. The SOS-LUX-LAC-FLUORO-Toxicity-test on the International Space Station (ISS)

    Science.gov (United States)

    Rabbow, E.; Rettberg, P.; Baumstark-Khan, C.; Horneck, G.

    In the 21 st century, an increasing number of astronauts will visit the International Space Station (ISS) for prolonged times. Therefore it is of utmost importance to provide necessary basic knowledge concerning risks to their health and their ability to work on the station and during extravehicular activities (EVA) in free space. It is the aim of one experiment of the German project TRIPLE-LUX (to be flown on the ISS) to provide an estimation of health risk resulting from exposure of the astronauts to the radiation in space inside the station as well as during extravehicular activities on one hand, and of exposure of astronauts to unavoidable or as yet unknown ISS-environmental genotoxic substances on the other. The project will (i) provide increased knowledge of the biological action of space radiation and enzymatic repair of DNA damage, (ii) uncover cellular mechanisms of synergistic interaction of microgravity and space radiation and (iii) examine the space craft milieu with highly specific biosensors. For these investigations, the bacterial biosensor SOS-LUX-LAC-FLUORO-Toxicity-test will be used, combining the SOS-LUX-Test invented at DLR Germany (Patent) with the commercially available LAC-FLUORO-Test. The SOS-LUX-Test comprises genetically modified bacteria transformed with the pBR322-derived plasmid pPLS-1. This plasmid carries the promoterless lux operon of Photobacterium leiognathi as a reporter element under control of the DNA-damage dependent SOS promoter of ColD as sensor element. This system reacts to radiation and other agents that induce DNA damages with a dose dependent measurable emission of bioluminescence of the transformed bacteria. The analogous LAC-FLUORO-Test has been developed for the detection of cellular responses to cytotoxins. It is based on the constitutive expression of green fluorescent protein (GFP) mediated by the bacterial protein expression vector pGFPuv (Clontech, Palo Alto, USA). In response to cytotoxic agents, this system

  15. The effect of stochasticity on the lac operon: an evolutionary perspective.

    Directory of Open Access Journals (Sweden)

    Milan van Hoek

    2007-06-01

    Full Text Available The role of stochasticity on gene expression is widely discussed. Both potential advantages and disadvantages have been revealed. In some systems, noise in gene expression has been quantified, in among others the lac operon of Escherichia coli. Whether stochastic gene expression in this system is detrimental or beneficial for the cells is, however, still unclear. We are interested in the effects of stochasticity from an evolutionary point of view. We study this question in the lac operon, taking a computational approach: using a detailed, quantitative, spatial model, we evolve through a mutation-selection process the shape of the promoter function and therewith the effective amount of stochasticity. We find that noise values for lactose, the natural inducer, are much lower than for artificial, nonmetabolizable inducers, because these artificial inducers experience a stronger positive feedback. In the evolved promoter functions, noise due to stochasticity in gene expression, when induced by lactose, only plays a very minor role in short-term physiological adaptation, because other sources of population heterogeneity dominate. Finally, promoter functions evolved in the stochastic model evolve to higher repressed transcription rates than those evolved in a deterministic version of the model. This causes these promoter functions to experience less stochasticity in gene expression. We show that a high repression rate and hence high stochasticity increases the delay in lactose uptake in a variable environment. We conclude that the lac operon evolved such that the impact of stochastic gene expression is minor in its natural environment, but happens to respond with much stronger stochasticity when confronted with artificial inducers. In this particular system, we have shown that stochasticity is detrimental. Moreover, we demonstrate that in silico evolution in a quantitative model, by mutating the parameters of interest, is a promising way to unravel

  16. Analysis and Remediation of the 2013 LAC-MÉGANTIC Train Derailment

    Science.gov (United States)

    Brunke, Suzanne; Aubé, Guy; Legaré, Serge; Auger, Claude

    2016-06-01

    On July 6, 2013 a train owned by Montréal, Maine & Atlantic Railway (MMA) Company derailed in Lac-Mégantic, Quebec, Canada triggering the explosion of the tankers carrying crude oil. Several buildings in the downtown core were destroyed. The Sûreté du Québec confirmed the death of 47 people in the disaster. Through the Canadian Space Agency (CSA) Rapid Information Products and Services (RIPS) program, MDA developed value-added products that allowed stakeholders and all levels of government (municipal, provincial and federal) to get an accurate picture of the disaster. The goal of this RIPS Project was to identify the contribution that remote sensing technology can provide to disasters such as the train derailment and explosion at Lac-Mégantic through response and remediation monitoring. Through monitoring and analysis, the Lac-Mégantic train derailment response and remediation demonstrated how Earth observation data can be used for situational awareness in a disaster and in documenting the remediation process. Both high resolution optical and RADARSAT-2 SAR image products were acquired and analyzed over the disaster remediation period as each had a role in monitoring. High resolution optical imagery provided a very clear picture of the current state of remediation efforts, however it can be difficult to acquire due to cloud cover and weather conditions. The RADARSAT-2 SAR images can be acquired in all weather conditions at any time of day making it ideal for mission critical information gathering. MDA's automated change detection processing enabled rapid delivery of advanced information products.

  17. ANALYSIS AND REMEDIATION OF THE 2013 LAC-MÉGANTIC TRAIN DERAILMENT

    Directory of Open Access Journals (Sweden)

    S. Brunke

    2016-06-01

    Full Text Available On July 6, 2013 a train owned by Montréal, Maine & Atlantic Railway (MMA Company derailed in Lac-Mégantic, Quebec, Canada triggering the explosion of the tankers carrying crude oil. Several buildings in the downtown core were destroyed. The Sûreté du Québec confirmed the death of 47 people in the disaster. Through the Canadian Space Agency (CSA Rapid Information Products and Services (RIPS program, MDA developed value-added products that allowed stakeholders and all levels of government (municipal, provincial and federal to get an accurate picture of the disaster. The goal of this RIPS Project was to identify the contribution that remote sensing technology can provide to disasters such as the train derailment and explosion at Lac-Mégantic through response and remediation monitoring. Through monitoring and analysis, the Lac-Mégantic train derailment response and remediation demonstrated how Earth observation data can be used for situational awareness in a disaster and in documenting the remediation process. Both high resolution optical and RADARSAT-2 SAR image products were acquired and analyzed over the disaster remediation period as each had a role in monitoring. High resolution optical imagery provided a very clear picture of the current state of remediation efforts, however it can be difficult to acquire due to cloud cover and weather conditions. The RADARSAT-2 SAR images can be acquired in all weather conditions at any time of day making it ideal for mission critical information gathering. MDA’s automated change detection processing enabled rapid delivery of advanced information products.

  18. High-level expression of Bacillus naganoensis pullulanase from recombinant Escherichia coli with auto-induction: effect of lac operator.

    Directory of Open Access Journals (Sweden)

    Yao Nie

    Full Text Available Pullulanase plays an important role in specific hydrolysis of branch points in amylopectin and is generally employed as an important enzyme in starch-processing industry. So far, however, the production level of pullulanase is still somewhat low from wide-type strains and even heterologous expression systems. Here the gene encoding Bacillus naganoensis pullulanase was amplified and cloned. For expression of the protein, two recombinant systems, Escherichia coli BL21(DE3/pET-20b(+-pul and E. coli BL21(DE3/pET-22b(+-pul, were constructed, both bearing T7 promoter and signal peptide sequence, but different in the existance of lac operator and lacI gene encoding lac repressor. Recombinant pullulanase was initially expressed with the activity of up to 14 U/mL by E. coli BL21(DE3/pET-20b(+-pul with IPTG induction in LB medium, but its expression level reduced continually with the extension of cryopreservation time and basal expression was observed. However, E. coli BL21(DE3/pET-22b(+-pul , involving lac operator downstream of T7 promoter to regulate foreign gene transcription, exhibited pullulanase activity consistently without detected basal expression. By investigating the effect of lac operator, basal expression of foreign protein was found to cause expression instability and negative effect on production of target protein. Thus double-repression strategy was proposed that lac operators in both chromosome and plasmid were bound with lac repressor to repress T7 RNA polymerase synthesis and target protein expression before induction. Consequently, the total activity of pullulanase was remarkably increased to 580 U/mL with auto-induction by lac operator-involved E. coli BL21(DE3/pET-22b(+-pul. When adding 0.6% glycine in culture, the extracellular production of pullulanase was significantly improved with the extracellular activity of 502 U/mL, which is a relatively higher level achieved to date for extracellular production of pullulanase. The

  19. Diverse effects of the MalE-LacZ hybrid protein on Escherichia coli cell physiology.

    OpenAIRE

    Ito, K.; Akiyama, Y; Yura, T; Shiba, K

    1986-01-01

    The hybrid protein between the periplasmic maltose-binding protein and the cytoplasmic beta-galactosidase (the MalE-LacZ hybrid protein) was previously shown to block the export of envelope proteins when synthesized in large amounts. Now we show that the hybrid protein exerts another major effect on the cell, that is, induction of the heat shock proteins. This latter effect was dependent on the htpR gene product but independent of the function of the signal sequence on the hybrid protein. On ...

  20. Hopf Bifurcation and Delay-Induced Turing Instability in a Diffusive lac Operon Model

    Science.gov (United States)

    Cao, Xin; Song, Yongli; Zhang, Tonghua

    In this paper, we investigate the dynamics of a lac operon model with delayed feedback and diffusion effect. If the system is without delay or the delay is small, the positive equilibrium is stable so that there are no spatial patterns formed; while the time delay is large enough the equilibrium becomes unstable so that rich spatiotemporal dynamics may occur. We have found that time delay can not only incur temporal oscillations but also induce imbalance in space. With different initial values, the system may have different spatial patterns, for instance, spirals with one head, four heads, nine heads, and even microspirals.

  1. Fertility in couples heterozygous for the tyrosinemia gene in Saguenay Lac-St-Jean.

    Science.gov (United States)

    De Braekeleer, M; Lamarre, V; Scriver, C R; Larochelle, J; Bouchard, G

    1990-01-01

    A case-control study of 84 couples from Saguenay-Lac-St-Jean, jointly heterozygous for the tyrosinemia gene, was done to determine whether the birth of an homozygous child affected their fertility rates. The mean number of children born to tyrosinemia and control couples between 1940 and 1986 was not different (p greater than 0.05). The knowledge that tyrosinemia was an autosomal recessive disorder, with risk of recurrence in these families, did not appear to modify reproductive behaviour. Fertility fell significantly in both the tyrosinemia and control families in the period of observation. This change reflects the decline in fertility of French Canadians in general during this period.

  2. Optical imaging of the host galaxies of X-ray selected BL Lacertae objects

    CERN Document Server

    Falomo, R

    1999-01-01

    We investigate the properties of the host galaxies of X-ray selected (high frequency peaked) BL Lac objects using a large and homogeneous data set of high spatial resolution R-band observations of 52 BL Lacs in the EMSS and Slew samples. The redshift distribution of the BL Lacs ranges from z = 0.04 to z>0.7, with average and median redshifts z = 0.26 and z = 0.24, respectively. Eight objects are at unknown redshift. We are able to resolve 45 objects out of the 52 BL Lacs. For all the well-resolved sources, we find the host to be a luminous elliptical galaxy. In a few cases a disk is not ruled out but an elliptical model is still preferred. The average absolute magnitude of the host galaxies is = -23.9+-0.6, while the average scale length of the host is = 9+-5 kpc. There is no difference in the host properties between the EMSS and Slew samples. We find a good agreement between the results derived by the surveys of Wurtz et al. (ground-based data) and Urry et al. (HST data), and by our new deeper imaging. The...

  3. Trusted Objects

    Energy Technology Data Exchange (ETDEWEB)

    CAMPBELL,PHILIP L.; PIERSON,LYNDON G.; WITZKE,EDWARD L.

    1999-10-27

    In the world of computers a trusted object is a collection of possibly-sensitive data and programs that can be allowed to reside and execute on a computer, even on an adversary's machine. Beyond the scope of one computer we believe that network-based agents in high-consequence and highly reliable applications will depend on this approach, and that the basis for such objects is what we call ''faithful execution.''

  4. Object theatre

    DEFF Research Database (Denmark)

    Ryöppy, Merja; Heiberg, Andreas

    2015-01-01

    possibilities to emerge. We present a study in which the Object Theatre approach is applied to redesign socially shared everyday products that are located in public places. This project demonstrates how Object Theatre offers a broad perspective form which to explore and present product interactions....... In particular, it emphasises the understanding of a product by relating and changing perspectives, and takes into account context of use and diverse social settings....

  5. Fashion Objects

    DEFF Research Database (Denmark)

    Andersen, Bjørn Schiermer

    2009-01-01

    This article attempts to create a framework for understanding modern fashion phenomena on the basis of Durkheim's sociology of religion. It focuses on Durkheim's conception of the relation between the cult and the sacred object, on his notion of 'exteriorisation', and on his theory of the social...... symbol in an attempt to describe the peculiar attraction of the fashion object and its social constitution. However, Durkheim's notions of cult and ritual must undergo profound changes if they are to be used in an analysis of fashion. The article tries to expand the Durkheimian cult, radically enlarging...... it without totally dispersing it; depicting it as held together exclusively by the sheer 'force' of the sacred object. Firstly, the article introduces the themes and problems surrounding Durkheim's conception of the sacred. Next, it briefly sketches an outline of fashion phenomena in Durkheimian categories...

  6. Adeno-associated Virus Mediated LacZ Gene Transfect to Cultured Human Iris Pigment Epithelium Cells

    Institute of Scientific and Technical Information of China (English)

    Chun Zhang; Shibo Tang; Yan Luo; Xiaoling Liang; Jing Ma; Shaofen Lin

    2003-01-01

    Purpose: To study the feasibility of adeno-associated virus mediated gene transfection tocultured human iris pigment epithelium (IPE) cells in vitro.Methods: Recombinant replication deficient adeno-associated viruses (AAV) expressingLacZ gene were produced without helper virus. The LacZ gene was transduced into culturedhuman IPE cells.Results: Cultured human IPE cells stained positively anticytokeratin, The titer ofrAAV-LacZ was 2.1 × 108 virus particles/ml, 42% cultured human IPE cells expressedβ-galactosidase 7 days after transfection and 67% after 14 days.Conclusions: Recombined AAV produced without helper virus can transfer a foreign geneinto human IPE cells with high efficiency in vitro.

  7. Validation of the LacTek test applied to spiked extracts of tissue samples: determination of performance characteristics.

    Science.gov (United States)

    Mitchell, J M; Yee, A J; McNab, W B; Griffiths, M W; McEwen, S A

    1999-01-01

    LacTek tests are competitive enzyme-linked immunosorbent assays intended for rapid detection of antimicrobial residues in bovine milk. In this study, the LacTek test protocol was modified for use with extracts of bovine tissue to detect beta-lactam, tetracycline, and sulfamethazine residues. Test performance characteristics--precision, accuracy, ruggedness, practicability, and analytical specificity and sensitivity--were investigated. Results suggest that LacTek tests can be easily adapted to detect antimicrobial residues in extracts of lean ground beef. However, positive samples may not contain residues at violative concentrations (i.e., Canadian maximum residue limits), and therefore, additional analysis would be required for final confirmation and quantitation (e.g., chromatography).

  8. In vitro transcription accurately predicts lac repressor phenotype in vivo in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Matthew Almond Sochor

    2014-07-01

    Full Text Available A multitude of studies have looked at the in vivo and in vitro behavior of the lac repressor binding to DNA and effector molecules in order to study transcriptional repression, however these studies are not always reconcilable. Here we use in vitro transcription to directly mimic the in vivo system in order to build a self consistent set of experiments to directly compare in vivo and in vitro genetic repression. A thermodynamic model of the lac repressor binding to operator DNA and effector is used to link DNA occupancy to either normalized in vitro mRNA product or normalized in vivo fluorescence of a regulated gene, YFP. An accurate measurement of repressor, DNA and effector concentrations were made both in vivo and in vitro allowing for direct modeling of the entire thermodynamic equilibrium. In vivo repression profiles are accurately predicted from the given in vitro parameters when molecular crowding is considered. Interestingly, our measured repressor–operator DNA affinity differs significantly from previous in vitro measurements. The literature values are unable to replicate in vivo binding data. We therefore conclude that the repressor-DNA affinity is much weaker than previously thought. This finding would suggest that in vitro techniques that are specifically designed to mimic the in vivo process may be necessary to replicate the native system.

  9. Evolution in Binary and Triple Stars, with an application to SS Lac

    CERN Document Server

    Eggleton, P P; Eggleton, Peter P.; Kiseleva-Eggleton, Ludmila

    2001-01-01

    We present equations governing the way in which both the orbit and the intrinsic spins of stars in a close binary should evolve subject to a number of perturbing forces, including the effect of a third body in a possibly inclined wider orbit. We illustrate the solutions in some binary-star and triple-star situations: tidal friction in a wide but eccentric orbit of a radio pulsar about a B star, the Darwin and eccentricity instabilities in a more massive but shorter-period massive X-ray binary, and the interaction of tidal friction with Kozai cycles in a triple such as Algol (beta-Per), at an early stage in that star's life when all 3 components were ZAMS stars. We also attempt to model in some detail the interesting triple system SS Lac, which stopped eclipsing in about 1950. We find that our model of SS Lac is quite constrained by the relatively good observational data of this system, and leads to a specific inclination (29 deg) of the outer orbit relative to the inner orbit at epoch zero (1912). Although th...

  10. Local gene regulation details a recognition code within the LacI transcriptional factor family.

    Directory of Open Access Journals (Sweden)

    Francisco M Camas

    Full Text Available The specific binding of regulatory proteins to DNA sequences exhibits no clear patterns of association between amino acids (AAs and nucleotides (NTs. This complexity of protein-DNA interactions raises the question of whether a simple set of wide-coverage recognition rules can ever be identified. Here, we analyzed this issue using the extensive LacI family of transcriptional factors (TFs. We searched for recognition patterns by introducing a new approach to phylogenetic footprinting, based on the pervasive presence of local regulation in prokaryotic transcriptional networks. We identified a set of specificity correlations--determined by two AAs of the TFs and two NTs in the binding sites--that is conserved throughout a dominant subgroup within the family regardless of the evolutionary distance, and that act as a relatively consistent recognition code. The proposed rules are confirmed with data of previous experimental studies and by events of convergent evolution in the phylogenetic tree. The presence of a code emphasizes the stable structural context of the LacI family, while defining a precise blueprint to reprogram TF specificity with many practical applications.

  11. Practical aspects of curvature detection for LACS free-form measuring systems

    Science.gov (United States)

    Schulz, Michael; Gerhardt, Joachim; Elster, Clemens

    2004-09-01

    For the production of aspheres and free-form surfaces, high-accuracy and flexible measurement techniques are necessary. The Large Area Curvature Scanning (LACS) method can be used to measure the surface form of arbitrary smooth surfaces with high accuracy. The curvature values of the surface elements along a scan line are captured by a curvature sensor and from these values the form is calculated. The curvature sensor typically is a small interferometer with an aperture of some millimeter. From a model fit to the measured interferogram, the local surface patch and the local curvature value are extracted. Determining the curvature values from the captured interferograms with high accuracy is a challenging task and requires some kind of intelligent procedures for defect recognition and for the choice of matched surface models. Several aspects of these problems are discussed. Examples of measured surfaces are shown. Special emphasis is laid on the measuring speed of the LACS system, which is mainly determined by the speed of the curvature evaluation procedure, as this is important for the use as an in-situ measurement system integrated into production systems.

  12. Lightning Detection by LAC Onboard the Japanese Venus Climate Orbiter, Planet-C

    Science.gov (United States)

    Takahashi, Y.; Yoshida, J.; Yair, Y.; Imamura, T.; Nakamura, M.

    2008-06-01

    Lightning activity in Venus has been a mystery for a long period, although many studies based on observations both by spacecraft and by ground-based telescope have been carried out. This situation may be attributed to the ambiguity of these evidential measurements. In order to conclude this controversial subject, we are developing a new type of lightning detector, LAC (Lightning and Airglow Camera), which will be onboard Planet-C (Venus Climate Orbiter: VCO). Planet-C will be launched in 2010 by JAXA. To distinguish an optical lightning flash from other pulsing noises, high-speed sampling at 50 kHz for each pixel, that enables us to investigate the time variation of each lightning flash phenomenon, is adopted. On the other hand, spatial resolution is not the first priority. For this purpose we developed a new type of APD (avalanche photo diode) array with a format of 8×8. A narrow band interference filter at wavelength of 777.4 nm (OI), which is the expected lightning color based on laboratory discharge experiment, is chosen for lightning measurement. LAC detects lightning flash with an optical intensity of average of Earth’s lightning or less at a distance of 3 Rv. In this paper, firstly we describe the background of the Venus lightning study to locate our spacecraft project, and then introduce the mission details.

  13. Intelligent Local Avoided Collision (iLAC) MAC Protocol for Very High Speed Wireless Network

    Science.gov (United States)

    Hieu, Dinh Chi; Masuda, Akeo; Rabarijaona, Verotiana Hanitriniala; Shimamoto, Shigeru

    Future wireless communication systems aim at very high data rates. As the medium access control (MAC) protocol plays the central role in determining the overall performance of the wireless system, designing a suitable MAC protocol is critical to fully exploit the benefit of high speed transmission that the physical layer (PHY) offers. In the latest 802.11n standard [2], the problem of long overhead has been addressed adequately but the issue of excessive colliding transmissions, especially in congested situation, remains untouched. The procedure of setting the backoff value is the heart of the 802.11 distributed coordination function (DCF) to avoid collision in which each station makes its own decision on how to avoid collision in the next transmission. However, collision avoidance is a problem that can not be solved by a single station. In this paper, we introduce a new MAC protocol called Intelligent Local Avoided Collision (iLAC) that redefines individual rationality in choosing the backoff counter value to avoid a colliding transmission. The distinguishing feature of iLAC is that it fundamentally changes this decision making process from collision avoidance to collaborative collision prevention. As a result, stations can avoid colliding transmissions with much greater precision. Analytical solution confirms the validity of this proposal and simulation results show that the proposed algorithm outperforms the conventional algorithms by a large margin.

  14. Dynamics and bistability in a reduced model of the lac operon

    Science.gov (United States)

    Yildirim, Necmettin; Santillán, Moisés; Horike, Daisuke; Mackey, Michael C.

    2004-06-01

    It is known that the lac operon regulatory pathway is capable of showing bistable behavior. This is an important complex feature, arising from the nonlinearity of the involved mechanisms, which is essential to understand the dynamic behavior of this molecular regulatory system. To find which of the mechanisms involved in the regulation of the lac operon is the origin of bistability, we take a previously published model which accounts for the dynamics of mRNA, lactose, allolactose, permease and β-galactosidase involvement and simplify it by ignoring permease dynamics (assuming a constant permease concentration). To test the behavior of the reduced model, three existing sets of data on β-galactosidase levels as a function of time are simulated and we obtain a reasonable agreement between the data and the model predictions. The steady states of the reduced model were numerically and analytically analyzed and it was shown that it may indeed display bistability, depending on the extracellular lactose concentration and growth rate.

  15. Learning Vector Quantization for Classifying Astronomical Objects

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The sizes of astronomical surveys in different wavebands are increas-ing rapidly. Therefore, automatic classification of objects is becoming ever moreimportant. We explore the performance of learning vector quantization (LVQ) inclassifying multi-wavelength data. Our analysis concentrates on separating activesources from non-active ones. Different classes of X-ray emitters populate distinctregions of a multidimensional parameter space. In order to explore the distributionof various objects in a multidimensional parameter space, we positionally cross-correlate the data of quasars, BL Lacs, active galaxies, stars and normal galaxiesin the optical, X-ray and infrared bands. We then apply LVQ to classify them withthe obtained data. Our results show that LVQ is an effective method for separatingAGNs from stars and normal galaxies with multi-wavelength data.

  16. 重组海洋细菌漆酶Lac15脱色人工合成纺织染料的潜力%Dye decolorization by bacterial laccase Lac15

    Institute of Scientific and Technical Information of China (English)

    房伟; 方泽民; 常飞; 彭惠; 张学成; 肖亚中

    2012-01-01

    以重组海洋细菌漆酶Lac15 (rLac15)为生物催化剂,对蒽醌类和偶氮类染料进行脱色,考察了rLac15对人工合成纺织染料的脱色潜能.通过研究催化的介体、酶量、pH、染料浓度以及温度对脱色效率的影响,进一步优化了rLac15对部分蒽醌类和偶氮类人工合成纺织染料的脱色条件.以丁香酸甲酯为介体,在pH 8.5、45℃条件下反应1 h,20 U/L rLac15对100 μmol/L偶氮染料类Acid Red 6B (AR-6B),Reactive Blue 194(M-2GE),Reactive Brilliant Orange (K-7R)和Reactive Blue 171 (KE-R)具有较好的脱色效果,脱色率分别达到95%、93%、76%和61%.随着染料浓度的增加,脱色率呈下降趋势,但当染料浓度达到200 μmol/L时,M-2GE和AR-6B仍可保持80%以上脱色率.在常温下,rLac15对AR-6B、M-2GE、K-7R和KE-R显示较高脱色率,25℃反应24 h,分别达到96%、86%、66%和66%.rLac15是具有常温以及偏碱性环境脱色能力的细菌漆酶,具有潜在工业应用价值.%We screened for laccase from a marine metagenomic library and obtained a bacterial laccase Lac 15 and studied its decolorization ability. Using synthetic azo dyes and anthraquinonic dyes as substrates, we investigated the dye decolorization ability of recombinant Lac 15 (rLac15). The purified rLacl5 had better decolorization ability towards the azo dyes than the anthraquinonic dyes. When incubated at 45 ℃ and pH 8.5 for 1 h with methylsyringate as the mediator, 20 U/L of rLacl5 could decolorize 95% of 100 μmol/L Acid Red 6B (AR-6B), 93% of Reactive Blue 194 (M-2GE), 76% of Reactive Brilliant Orange (K-7R) and 66% of Reactive Blue 171 (KE-R). The decolorization ability of rLacl5 decreased with the dye concentration increasing. However, more than 80% of M-2GE and AR-6B were degraded even when the dye concentration was up to 200 umol/L. At room temperature, rLac51 exhibited significant decolorization ability, with 96% of AR-6B, 86% of M-2GE, 66% of K-7R and 66% of KE-R degraded

  17. Multi-Wave Luminosity of High-Synchrotron-Peaked TeV BL Lacs Detected by Fermi LAT

    Indian Academy of Sciences (India)

    Dingrong Xiong; Xiong Zhang; Yonggang Zheng

    2014-09-01

    We have studied the correlations between luminosities (R, IR, ) in the radio, near-infrared and -ray wave bands for HSP TeV BL Lacs. The results show that there are significant intrinsic correlations between R and and between IR and in all states (high/average/low), and suggest that for HSP TeV BL Lacs, the Synchrotron Self-Compton radiation (SSC) is the main mechanism of high energy -ray emission, and the inverse Compton scattering of circum-nuclear dust is likely to be an important complementary mechanism.

  18. A KPC-scale X-ray jet in the BL LAC Source S5 2007+777

    Science.gov (United States)

    Sambruna, Rita; Maraschi, Laura; Tavecchio, Fabrizio

    2008-01-01

    The BL Lac S3 2007++777, a classical radio-selected BL Lac from the sample of Stirkel et al. exhibiting an extended (19") radio jet. was observed with Chandra revealing an X-ray jet with simi1ar morphology. The hard X-ray spectrum and broad band SED is consistent with an IC/CMB origin for the X-ray emission, implying a highly relativistic flow at small angle to the line of sight with an unusually large deprojected length, 300 kpc. A structured jet consisting of a fast spine and slow wall is consistent with the observations.

  19. A fire history derived from Pinus resinosa Ait. for the Islands of Eastern Lac La Croix, Minnesota, USA.

    Science.gov (United States)

    Johnson, Lane B; Kipfmueller, Kurt F

    2016-06-01

    We reconstructed fire occurrence near a fur-trade era canoe travel corridor (used ca. 1780-1802) in the Quetico-Superior region west of Lake Superior to explore the possibility of human influence on pre-fire suppression rates of fire occurrence. Our research objectives were to (1) examine the spatial and temporal patterns of fire in the study area, (2) test fires' strength of association with regional drought, and (3) assess whether reconstructed fire frequencies could be explained by observed rates of lightning fire ignition over the modern period of record. We developed a 420-year fire history for the eastern portion of Lac La Croix in the Boundary Waters Canoe Area Wilderness (BWCAW). Seventy-one fire-scarred samples were collected from remnant Pinus resinosa Ait. (red pine) stumps and logs from thirteen distinct island and three mainland forest stands. Collectively these samples contained records of 255 individual fire scars representing 79 fire events from 1636 to 1933 (study area mean fire intervals [MFI] 3.8 yr). Reconstructed fires were spatially and temporally asynchronous and not strongly associated with regional drought (P > 0.05). When compared to the conservative, tree-ring reconstructed estimate of historical fire occurrence and modern lightning-caused fires (1929-2012), a noticeable change in the distribution and frequency of fires within the study area was evident with only two lightning-ignited island fires since 1934 in the study area. Our results suggest a high likelihood that indigenous land use contributed to surface fire ignitions within our study area and highlights the importance of examining the potential effects of past indigenous land use when determining modern approaches to fire and wilderness management in fire-adapted ecosystems.

  20. Objective becoming

    CERN Document Server

    Skow, Bradford

    2015-01-01

    Bradford Skow presents an original defense of the 'block universe' theory of time, often said to be a theory according to which time does not pass. Along the way, he provides in-depth discussions of alternative theories of time, including those in which there is 'robust passage' of time or 'objective becoming': presentism, the moving spotlight theory of time, the growing block theory of time, and the 'branching time' theory of time. Skow explains why the moving spotlight theory is the best of these arguments, and rebuts several popular arguments against the thesis that time passes. He surveys the problems that the special theory of relativity has been thought to raise for objective becoming, and suggests ways in which fans of objective becoming may reconcile their view with relativistic physics. The last third of the book aims to clarify and evaluate the argument that we should believe that time passes because, somehow, the passage of time is given to us in experience. He isolates three separate arguments thi...

  1. Influence of nucleotide excision repair on N-hydroxy-2-acetylaminofluorene-induced mutagenesis studied in λlacZ-transgenic mice

    NARCIS (Netherlands)

    Frijhoff, A.F.W.; Krul, C.A.M.; Vries, A. de; Kelders, M.C.J.M.; Weeda, G.; Steeg, H. van; Baan, R.A.

    1998-01-01

    To study the influence of nucleotide excision repair (NER) on mutagenesis in vivo, ERCC1+/-, XPA-/-, and wild-type (ERCC1+/+ and XPA+/+, respectively) λlacZ-transgenic mice were treated i.p. with N-hydroxy-2-acetylaminofluorene (N-OH-AAF) and lacZ mutant frequencies were determined in liver. No sign

  2. Molecular mechanism of LacZ gene mutagenesis induced by 9-aminoacridine%9-氨基吖啶诱导LacZ靶基因突变分子机制的研究

    Institute of Scientific and Technical Information of China (English)

    刘勇; 曹佳; 孙华明

    2001-01-01

    目的 使用我室新构建的含LacZ靶基因的λgt11DNA体外重包装致突变检测系统,研究了移码突变剂9-氨基吖啶(9-AA)诱发突变及分子突变谱,并进一步对该系统的可行性进行了评价。方法 用9-AA直接处理λgt11DNA,经体外重包装为完整噬菌体、铺皿,通过X-gal和IPTG检测突变率,使用DNA测序了解阳性克隆DNA分子改变情况。结果 9-AA能明显影响噬菌体的存活率和诱发DNA突变,突变率呈明显剂量-反应关系;9-AA主要诱发移码突变,移码突变主要集中在Gs、Cs、As、Ts重复区内且突变频率随碱基重复长度增加而增加;9-AA同时还能诱发碱基置换,碱基置换主要表现为颠换,而碱基转换主要发生于Gs碱基。结论 该致突变检测系统不仅可以快速,灵敏地筛选出外来化合物的遗传毒性,而且可以深入分析外来化合物致突变分子机制。%Objective To analyze the mechanism of molecular mutagenesisinduced by the 9-aminoacridine (9-AA) with the molecular mutation detective system of λ gt11DNA with LacZ gene and to evaluate this detective system. Methods The 9-AA-damaged λ gt11DNA was added to Lambda packaging extracts and then the repacked Lambda phage were cultured in E.coli Y1090 on a selective plate pre-supplemented with X-Gal and IPTG. The positive cloned DNA molecule was determined with DNA sequencer. Results 9-AA had an obvious effect on the survival rate of the Lambda phage and induce DNA mutation in a dose-effect manner. The 9-AA induced not only frameshift mutations, but also base substitutions. The frameshift mutation mainly occurred in the repeats of As, Cs, Gs. and Ts, and the frequency elevated linearly with the increasing amount of As, Cs, Gs, and Ts in the repeat. The 9-AA-induced base substitutions were mainly base transversion, and the base transition was only in Gs repeat. Conclusion With this mutagenesis detective system, the genetic toxicity of exogenous

  3. Surviving Objects

    OpenAIRE

    Murjas, Teresa

    2012-01-01

    Surviving Objects (2012) is a devised multi-media practice-as-research performance based on extensive interviews conducted with my elderly mother and recorded on a hand-held device. Our conversations concern her experiences as a child refugee following violent deportation by the Soviet Army from Eastern Poland to Siberia (1941), and her subsequent route, via Persia, to a British-run refugee camp in Northern Rhodesia, where she remained for 6 years before arriving in the UK. In order to aid my...

  4. Sliding and target location of DNA-binding proteins: an NMR view of the lac repressor system.

    Science.gov (United States)

    Loth, Karine; Gnida, Manuel; Romanuka, Julija; Kaptein, Robert; Boelens, Rolf

    2013-05-01

    In non-specific lac headpiece-DNA complexes selective NMR line broadening is observed that strongly depends on length and composition of the DNA fragments. This broadening involves amide protons found in the non-specific lac-DNA structure to be interacting with the DNA phosphate backbone, and can be ascribed to DNA sliding of the protein along the DNA. This NMR exchange broadening has been used to estimate the 1D diffusion constant for sliding along non-specific DNA. The observed 1D diffusion constant of 4×10(-12) cm(2)/s is two orders of magnitude smaller than derived from previous kinetic experiments, but falls in the range of values determined more recently using single molecule methods. This strongly supports the notion that sliding could play at most a minor role in the association kinetics of binding of lac repressor to lac operator and that other processes such as hopping and intersegment transfer contribute to facilitate the DNA recognition process.

  5. DNA adducts, mutant frequencies, and mutation spectra in various organs of λlacZ mice exposed to ethylating agents

    NARCIS (Netherlands)

    Mientjes, E.J.; Luiten-Schuite, A.; Wolf, E. van der; Borsboom, Y.; Bergmans, A.; Berends, F.; Lohman, P.H.M.; Baan, R.A.; Delft, J.H.M. van

    1998-01-01

    To investigate tissue-specific relations between DNA adducts and mutagenesis in vivo, λlacZ transgenic mice were treated i.p. with N-ethyl-N-nitrosourea (ENU), diethylnitrosamine (DEN), and ethyl methanesulphonate (EMS). In liver, bone marrow, and brain DNA from mice sacrificed at several time point

  6. Sliding and target location of DNA-binding proteins:an NMR view of the lac repressor system

    Energy Technology Data Exchange (ETDEWEB)

    Loth, Karine [Utrecht University, Bijvoet Center for Biomolecular Research, NMR Spectroscopy (Netherlands); Gnida, Manuel; Romanuka, Julija [Paderborn University, Department of Chemistry (Germany); Kaptein, Robert; Boelens, Rolf, E-mail: r.boelens@uu.nl [Utrecht University, Bijvoet Center for Biomolecular Research, NMR Spectroscopy (Netherlands)

    2013-05-15

    In non-specific lac headpiece-DNA complexes selective NMR line broadening is observed that strongly depends on length and composition of the DNA fragments. This broadening involves amide protons found in the non-specific lac-DNA structure to be interacting with the DNA phosphate backbone, and can be ascribed to DNA sliding of the protein along the DNA. This NMR exchange broadening has been used to estimate the 1D diffusion constant for sliding along non-specific DNA. The observed 1D diffusion constant of 4 Multiplication-Sign 10{sup -12} cm{sup 2}/s is two orders of magnitude smaller than derived from previous kinetic experiments, but falls in the range of values determined more recently using single molecule methods. This strongly supports the notion that sliding could play at most a minor role in the association kinetics of binding of lac repressor to lac operator and that other processes such as hopping and intersegment transfer contribute to facilitate the DNA recognition process.

  7. Characterization of Site-Directed Mutants in the lac Permease of Escherichia coli. 1. Replacement of Histidine Residues

    NARCIS (Netherlands)

    Püttner, Irene B.; Sarkar, Hemanta K.; Padan, Etana; Lolkema, Julius S.; Kaback, H. Ronald

    1989-01-01

    Wild-type lac permease from Escherichia coli and two site-directed mutant permeases containing Arg in place of His35 and His39 or His322 were purified and reconstituted into proteoliposomes. H35-39R permease is indistinguishable from wild type with regard to all modes of translocation. In contrast,

  8. Structure-Based Rational Design to Enhance the Solubility and Thermostability of a Bacterial Laccase Lac15

    Science.gov (United States)

    Fang, Zemin; Zhou, Peng; Chang, Fei; Yin, Qiang; Fang, Wei; Yuan, Jing; Zhang, Xuecheng; Xiao, Yazhong

    2014-01-01

    Bacterial laccases are ideal alternatives of fungal laccases for specific industrial applications due to specific characteristics such as alkalescence dependence and high chloride tolerance. However, some bacterial laccases presented as inclusion bodies when expressing in Escherichia coli and showed thermal instability. In this study, rational design was employed to enhance the solubility and the thermostablity of the bacterial laccase Lac15-His6 based on the crystal structure obtained previously. After deletion of His-tag and residues323–332, the obtained Lac15D was completely expressed in soluble form even at a higher temperature of 28°C, compared to only 50% of Lac15-His6 expressed solubly at 16°C. It showed a two-time higher activity at temperatures lower than 35°C and a half-life increasing from 72 min to 150 min at 45°C. When used in chromogenic reactions, Lac15D showed constant activity toward dye precursors and their combinations under alkaline conditions, demonstrating its application potential in hair coloring biotechnology. PMID:25036001

  9. Characterization of Site-Directed Mutants in the lac Permease of Escherichia coli. 2. Glutamate-325 Replacements

    NARCIS (Netherlands)

    Carrasco, Nancy; Püttner, Irene B.; Antes, Lisa M.; Lee, Jonathan A.; Larigan, J. Douglas; Lolkema, Julius S.; Roepe, Paul D.; Kaback, H. Ronald

    1989-01-01

    lac permease with Ala in place of Glu325 was solubilized from the membrane, purified, and reconstituted into proteoliposomes. The reconstituted molecule is completely unable to catalyze lactose/H+ symport but catalyzes exchange and counterflow at least as well as wild-type permease. In addition, Ala

  10. Structure-based rational design to enhance the solubility and thermostability of a bacterial laccase Lac15.

    Directory of Open Access Journals (Sweden)

    Zemin Fang

    Full Text Available Bacterial laccases are ideal alternatives of fungal laccases for specific industrial applications due to specific characteristics such as alkalescence dependence and high chloride tolerance. However, some bacterial laccases presented as inclusion bodies when expressing in Escherichia coli and showed thermal instability. In this study, rational design was employed to enhance the solubility and the thermostablity of the bacterial laccase Lac15-His6 based on the crystal structure obtained previously. After deletion of His-tag and residues323-332, the obtained Lac15D was completely expressed in soluble form even at a higher temperature of 28°C, compared to only 50% of Lac15-His6 expressed solubly at 16°C. It showed a two-time higher activity at temperatures lower than 35°C and a half-life increasing from 72 min to 150 min at 45°C. When used in chromogenic reactions, Lac15D showed constant activity toward dye precursors and their combinations under alkaline conditions, demonstrating its application potential in hair coloring biotechnology.

  11. Bird communities of contrasting semi-natural habitats of Lac bay, Bonaire, during the fall migration season, 2011

    NARCIS (Netherlands)

    Debrot, A.O.; Bemmelen, van R.S.A.; Ligon, J.

    2013-01-01

    The mangrove and seagrass lagoon of Lac Bay on Bonaire covers an area of roughly 700 ha. It is home to endangered green sea turtles, Chelonia mydas, and the Caribbean queen conch, Strombus gigas, and is a roosting and breeding area for several birds. Based on its nature values this 7 km2 bay has bee

  12. Infant mortality in myotonic dystrophy in Saguenay-Lac-St-Jean: a historical perspective.

    Science.gov (United States)

    Dao, T N; Mathieu, J; Bouchard, J P; De Braekeleer, M

    1993-01-01

    Infant mortality among children born to 373 individuals with myotonic dystrophy (MD) who lived in Saguenay-Lac-St-Jean during the period 1838 to the present time was analyzed using a case-control approach based on a population register. A statistically significant increase was found in the rate of deaths during the first week of life among children born to MD mothers (57.5%) compared to control mothers (34.8%) and MD fathers (39.1%) (p < 0.01). The stillbirth rate was not increased. The rate of mortality after the first week fell significantly in both MD and control groups during the period of observation. There was evidence of a slight selective disadvantage among this MD population.

  13. Autosomal recessive disorders in Saguenay-Lac-Saint-Jean (Quebec, Canada): a study of inbreeding.

    Science.gov (United States)

    De Braekeleer, M; Gauthier, S

    1996-01-01

    Saguenay Lac-Saint-Jean (SLSJ) is a geographically isolated region of northeastern Quebec in which several autosomal recessive disorders have a high incidence. We calculated the inbreeding coefficients of 567 probands and compared them to 1701 matched control individuals. The mean inbreeding coefficient of the group containing all 567 probands was 2.73 times higher than that of the controls (0.001772 versus 0.00065). Thirteen percent (75/567) of the probands were inbred, but only 5% were born to matings between spouses related as second-degree cousins or closer. No marriage between uncle and niece and only two marriages between first-degree cousins were identified in the disorder group. These results strongly suggest that the high incidence of the autosomal recessive disorders in SLSJ is the result of a founder effect.

  14. Population genetics of hereditary hemochromatosis in Saguenay Lac-Saint-Jean (Quebec, Canada).

    Science.gov (United States)

    de Braekeleer, M; Vigneault, A; Simard, H

    1992-01-01

    Hereditary hemochromatosis (HH) is an autosomal recessive disorder that has a high prevalence in Caucasian populations. Based on HLA typing in 18 families, the gene frequency was estimated 0.12. The homozygote frequency was 0.014 and the heterozygote frequency was 0.21 in Saguenay Lac-Saint-Jean (SLSJ), a geographically isolated region of northeastern Quebec. The genealogical reconstruction showed that 15 of the 57 obligate carriers of the HH gene could be traced back to a unique ancestor in the 18th century. The mean coefficients of inbreeding and kinship were 17 and 15 times, respectively, higher in the HH group than in three control groups. The values of both coefficients were much higher than those found in other HH populations and in most of the other recessive disorders prevalent in SLSJ.

  15. Genetic epidemiology of cystic fibrosis in Saguenay-Lac-St-Jean (Quebec, Canada).

    Science.gov (United States)

    Daigneault, J; Aubin, G; Simard, F; De Braekeleer, M

    1991-10-01

    Cystic fibrosis (CF) is an autosomal recessive disorder with a prevalence at birth estimated at 1/2000-1/2500 livebirths in Caucasian populations. Some 127 CF individuals are known in Saguenay-Lac-St-Jean (SLSJ), a geographically isolated region of Quebec. The prevalence at birth was estimated at 1/902 live borns, and the carrier rate was estimated at 1/15 inhabitants in the SLSJ region. The mean inbreeding coefficient was only slightly elevated in the CF group compared with three control groups, and was due to remote consanguinity. The mean kinship coefficient was 2.4 times higher in the CF group than in the control groups. In SLSJ region, the places of origin of the CF individuals and their parents did not show a clustered nonuniform distribution. Endogamy was not higher in the CF group than in control groups.

  16. H 0323 + 022 - A new BL Lacertae object with extremely rapid variability

    Science.gov (United States)

    Feigelson, E. D.; Bradt, H.; McClintock, J.; Remillard, R.; Urry, C. M.; Tapia, S.; Geldzahler, B.; Johnston, K.; Romanishin, W.; Wehinger, P. A.; Wyckoff, S.; Madejski, G.; Schwartz, D. A.; Thorstensen, J.; Schaefer, B. E.

    1986-03-01

    H0323+022 is a highly variable X-ray source discovered in the HEAO 1 all-sky survey coincident with a 16th mag stellar object. Optical nebulosity around the object strongly suggests that it is a BL Lac object. This paper presents the results of a multiband, multiepoch series of observations that demonstrate beyond reasonable doubt that H0323+022 is a remarkably variable BL Lac object. The optical nebulosity around the stellar object is confirmed, the stellar optical radiation is polarized, and the radio characteristics and the overall electromagnetic spectrum resemble those of other BL Lac objects. Variability is seen in all bands, including radio and broad-band optical variations in days, optical polarization changes on time scales of tens of minutes, and X-ray changes on time scales of ≡30 s. H0323+022 is thus an active galactic nucleus with much of the observed emission emerging from a region ⪉1012 - 1014cm in size.

  17. Objective thermomechanics

    CERN Document Server

    Fülöp, Tamás

    2015-01-01

    An irreversible thermodynamical theory of solids is presented where the kinematic quantities are defined in an automatically objective way. Namely, auxiliary elements like reference frame, reference time and reference configuration are avoided by formulating the motion of the continuum on spacetime directly, utilizing the Weyl-Matolcsi description of spacetime. This restricts the range of definable kinematic quantities heavily. Solids are distinguished from fluids by possessing not only an instantaneous metric tensor but a relaxed metric, too, that represents the natural geometric structure of the solid. The comparison of the instantaneous metric to the relaxed one is the basis of the definition of the elastic state variable, the elastic deformedness tensor. Thermal expansion is conceived as the temperature dependence of the relaxed metric. As opposed to this reversible type of change, plasticity means an irreversible change in the relaxed metric, and is describable via a plastic change rate tensor. The relat...

  18. Interplay of protein and DNA structure revealed in simulations of the lac operon.

    Directory of Open Access Journals (Sweden)

    Luke Czapla

    Full Text Available The E. coli Lac repressor is the classic textbook example of a protein that attaches to widely spaced sites along a genome and forces the intervening DNA into a loop. The short loops implicated in the regulation of the lac operon suggest the involvement of factors other than DNA and repressor in gene control. The molecular simulations presented here examine two likely structural contributions to the in-vivo looping of bacterial DNA: the distortions of the double helix introduced upon association of the highly abundant, nonspecific nucleoid protein HU and the large-scale deformations of the repressor detected in low-resolution experiments. The computations take account of the three-dimensional arrangements of nucleotides and amino acids found in crystal structures of DNA with the two proteins, the natural rest state and deformational properties of protein-free DNA, and the constraints on looping imposed by the conformation of the repressor and the orientation of bound DNA. The predicted looping propensities capture the complex, chain-length-dependent variation in repression efficacy extracted from gene expression studies and in vitro experiments and reveal unexpected chain-length-dependent variations in the uptake of HU, the deformation of repressor, and the folding of DNA. Both the opening of repressor and the presence of HU, at levels approximating those found in vivo, enhance the probability of loop formation. HU affects the global organization of the repressor and the opening of repressor influences the levels of HU binding to DNA. The length of the loop determines whether the DNA adopts antiparallel or parallel orientations on the repressor, whether the repressor is opened or closed, and how many HU molecules bind to the loop. The collective behavior of proteins and DNA is greater than the sum of the parts and hints of ways in which multiple proteins may coordinate the packaging and processing of genetic information.

  19. Radial derivatives of the mouse ventral pallium traced with Dbx1-LacZ reporters.

    Science.gov (United States)

    Puelles, Luis; Medina, Loreta; Borello, Ugo; Legaz, Isabel; Teissier, Anne; Pierani, Alessandra; Rubenstein, John L R

    2016-09-01

    The progeny of Dbx1-expressing progenitors was studied in the developing mouse pallium, using two transgenic mouse lines: (1) Dbx1(nlslacZ) mice, in which the gene of the β-galactosidase reporter (LacZ) is inserted directly under the control of the Dbx1 promoter, allowing short-term lineage tracing of Dbx1-derived cells; and (2) Dbx1(CRE) mice crossed with a Cre-dependent reporter strain (ROSA26(loxP-stop-loxP-LacZ)), in which the Dbx1-derived cells result permanently labeled (Bielle et al., 2005). We thus examined in detail the derivatives of the postulated longitudinal ventral pallium (VPall) sector, which has been defined among other features by its selective ventricular zone expression of Dbx1 (the recent ascription by Puelles, 2014 of the whole olfactory cortex primordium to the VPall was tested). Earlier notions about a gradiental caudorostral reduction of Dbx1 signal were corroborated, so that virtually no signal was found at the olfactory bulb and the anterior olfactory area. The piriform cortex was increasingly labeled caudalwards. The only endopiriform grisea labeled were the ventral endopiriform nucleus and the bed nucleus of the external capsule. Anterior and basolateral parts of the whole pallial amygdala also were densely marked, in contrast to the negative posterior parts of these pallial amygdalar nuclei (leaving apart medial amygdalar parts ascribed to subpallial or extratelencephalic sources of Dbx1-derived GABAergic and non-GABAergic neurons). Alternative tentative interpretations are discussed to explain the partial labeling obtained of both olfactory and amygdaloid structures. This includes the hypothesis of an as yet undefined part of the pallium, potentially responsible for the posterior amygdala, or the hypothesis that the VPall may not be wholly characterized by Dbx1 expression (this gene not being necessary for VPall molecular distinctness and histogenetic potency), which would leave a dorsal Dbx1-negative VPall subdomain of variable size

  20. Formation and persistence of O6-ethylguanine in genomic and transgene DNA in liver and brain of λlacZ transgenic mice treated with N-ethyl-N-nitrosourea

    NARCIS (Netherlands)

    Mientjes, E.J.; Hochleitner, K.; Luiten-Schuite, A.; Delft, J.H.M. van; Thomale, J.; Berends, F.; Rajewsky, M.F.; Lohman, P.H.M.; Baan, R.A.

    1996-01-01

    LacZ transgenic mice are suitable for short-term mutagenicity studies in vivo. Mutagenicity in these mice is determined in the lacZ transgene. Since the lacZ gene is of bacterial origin the question has been raised whether DNA-adduct formation and repair in the transgene are comparable to those in t

  1. Non-variable TeV emission from the extended jet of a blazar in the stochastic acceleration scenario: the case of the hard TeV emission of 1ES 1101-232

    Science.gov (United States)

    Yan, Dahai; Zeng, Houdun; Zhang, Li

    2012-08-01

    The detections of X-ray emission from the kiloparsec-scale jets of blazars and radio galaxies could imply the existence of high-energy electrons in these extended jets, and these electrons could produce high-energy emission through the inverse Compton (IC) process. In this paper, we study the non-variable hard TeV emission from a blazar. The multiband emission consists of two components: (i) the traditional synchrotron self-Compton (SSC) emission from the inner jet; (ii) the emission produced via SSC and IC scattering of cosmic microwave background (CMB) photons (IC/CMB) and extragalactic background light (EBL) photons by relativistic electrons in the extended jet under the stochastic acceleration scenario. Such a model is applied to 1ES 1101-232. The results indicate the following. (i) The non-variable hard TeV emission of 1ES 1101-232, which is dominated by IC/CMB emission from the extended jet, can be reproduced well by using three characteristic values of the Doppler factor (δD = 5, 10 and 15) for the TeV-emitting region in the extended jet. (ii) In the cases of δD = 15 and 10, the physical parameters can achieve equipartition (or quasi-equipartition) between the relativistic electrons and the magnetic field. In contrast, the physical parameters largely deviate from equipartition for the case of δD = 5. Therefore, we conclude that the TeV emission region of 1ES 1101-232 in the extended jet should be moderately or highly beamed.

  2. Soft X-Ray Observations of a Complete Sample of X-Ray--selected BL Lacertae Objects

    Science.gov (United States)

    Perlman, Eric S.; Stocke, John T.; Wang, Q. Daniel; Morris, Simon L.

    1996-01-01

    We present the results of ROSAT PSPC observations of the X-ray selected BL Lacertae objects (XBLs) in the complete Einstein Extended Medium Sensitivity Survey (EM MS) sample. None of the objects is resolved in their respective PSPC images, but all are easily detected. All BL Lac objects in this sample are well-fitted by single power laws. Their X-ray spectra exhibit a variety of spectral slopes, with best-fit energy power-law spectral indices between α = 0.5-2.3. The PSPC spectra of this sample are slightly steeper than those typical of flat ratio-spectrum quasars. Because almost all of the individual PSPC spectral indices are equal to or slightly steeper than the overall optical to X-ray spectral indices for these same objects, we infer that BL Lac soft X-ray continua are dominated by steep-spectrum synchrotron radiation from a broad X-ray jet, rather than flat-spectrum inverse Compton radiation linked to the narrower radio/millimeter jet. The softness of the X-ray spectra of these XBLs revives the possibility proposed by Guilbert, Fabian, & McCray (1983) that BL Lac objects are lineless because the circumnuclear gas cannot be heated sufficiently to permit two stable gas phases, the cooler of which would comprise the broad emission-line clouds. Because unified schemes predict that hard self-Compton radiation is beamed only into a small solid angle in BL Lac objects, the steep-spectrum synchrotron tail controls the temperature of the circumnuclear gas at r ≤ 1018 cm and prevents broad-line cloud formation. We use these new ROSAT data to recalculate the X-ray luminosity function and cosmological evolution of the complete EMSS sample by determining accurate K-corrections for the sample and estimating the effects of variability and the possibility of incompleteness in the sample. Our analysis confirms that XBLs are evolving "negatively," opposite in sense to quasars, with Ve/Va = 0.331±0.060. The statistically significant difference between the values for X

  3. Non-variable TeV emission from the extended jet of a blazar in the stochastic acceleration scenario: the case of the hard TeV emission of 1ES 1101-232

    CERN Document Server

    Yan, Dahai; Zhang, Li

    2012-01-01

    The detections of X-ray emission from the kiloparsec-scale jets of blazars and radio galaxies may imply the existence of high energy electrons in these extended jets, and these electrons could produce high energy emission through inverse Compton (IC) process. In this paper we study the non-variable hard TeV emission from a blazar. The multi-band emission consists of two components: one is the traditional synchrotron self-Compton (SSC) emission from the inner jet, and the other is the emission produced via SSC and IC scattering of cosmic microwave background (CMB) photons (IC/CMB) and extragalactic background light (EBL) photons (IC/EBL) by relativistic electrons in the extended jet under the stochastic acceleration scenario. Such a model is applied to 1ES 1101-232. The results indicate that (1) the non-variable hard TeV emission of 1ES 1101-232 can be reproduced well, which is dominated by IC/CMB emission from the extended jet, using three characteristic values of Doppler factor ($\\delta_{\\rm D}=5,10,15$) for...

  4. The HC-LAC: a Platform for Modeling Hydrology and Climate Change in Latin America and the Caribbean

    Science.gov (United States)

    Moreda, F.; Wyatt, A.; Bruhn, M.; Wheaton, W.; Miralles-Wilhelm, F.; Muñoz-Castillo, R.; Rineer, J.

    2013-05-01

    This platform, called the Hydrology and Climate Change in Latin America and The Caribbean, or "HC-LAC", is an integrated quantitative simulation of hydrology and climate change. The HC-LAC is composed of two principal components: the Analytical Hydrography Dataset (AHD) and an enhanced version of the Generalized Watershed Loading Function (GWLF). The AHD is a spatially explicit surface water data layer of Central and South America derived from digital elevation data from the Shuttle Radar Topography Mission (SRTM) and modified by the USGS to provide more accurate flow between cells in the raster data. For the LAC area, AHD consists 230, 000 catchments and stream segments with an average area of 100 km2 and length of 10 km, respectively. The AHD data structure is patterned after the US National Hydrography Dataset Plus (NHDPlus), thus providing a proven structure for flexible data integration and analyses necessary for spatial models like the HC-LAC. The structure of the AHD enables the implementation of water balance modeling and general routing of flows through the stream network thus supporting a range of environmental models. GWLF is applied on each AHD catchment which is characterized by multiple land use and soil type. The response of each land use in a given catchment is modeled separately in generating stream flow as well as recharge to soil storage. The stream flows generated from each catchment are routed through stream networks, providing total flow at any point in the stream network. A pilot implementation of the HC-LAC was established for the Rio Grande basin in North West Argentina (drainage area 6,700 km2). The model was parameterized and calibrated using readily available data. Three stream flow time series were generated using a reference climate case and two climate change projections. The reference case was based on historical records and assumes no climate change. The two climate change projections were generated using the IPCC "A2" high

  5. The Lac-Mégantic Derailment, Corporate Regulation, and Neoliberal Sovereignty.

    Science.gov (United States)

    Dunford, David Tyler

    2017-02-01

    On July 6, 2013, Montreal, Maine, and Atlantic railcar 5017 hauling 72 tanker cars of Bakken crude oil derailed over the town of Lac-Mégantic, Quebec. The town erupted in a fiery inferno as 5,560,000 liters of highly flammable Bakken crude oil exploded over the town, killing 47 people and contaminating 558,000 tons of soil and local waterways. While Montreal, Maine, and Atlantic Rail Chairman Edward Burkhardt initially blamed the derailment on the lone engineer and local firefighters, this study shows how Transport Canada and the rail industry undermined regulatory and safety measures for several years before the derailment. This study uses a Foucauldian theoretical perspective to conceptualize and explain a new political mentality that transfers existing state regulatory authority to the corporate sector. This new mentality, neoliberal sovereignty, is composed of sovereign and neoliberal logics that monopolize "correct" trajectories of human economic development. This absolute market mentality merges with state sovereignty and eliminates existing safety and regulation frameworks to pursue unregulated corporate profits. Le 6 juillet 2013, un train de 72 wagons-citernes transportant du pétrole brute Bakken a déraillé de la ligne de chemin de fer de la Montréal, Maine et Atlantique, dans la ville de Lac-Mégantic au Québec. La ville c'est transformé en véritable enfer, alors que 5 560 000 litre de pétrole brute Bakken très inflammable ont fait explosé la ville, tuant quarante-sept personnes et contaminant 558 000 tonnes d'eaux et du sol de Lac-Mégantic et ses environs. Alors que le président de la MMA, Edward Burkhart, a d'abord blâmé l'ingénieur et le service d'incendie local, les études montrent que Transport Canada et l'industrie ferroviaire ont amoindrit les mesures de réglementation et de sécurité plusieurs années avant le déraillement. Cette étude utilise une perspective théorique foucauldienne pour conceptualiser et expliquer une

  6. Appui au volet " Professionnalisation des organisations de producteurs " du projet BV-LAC. Utilisation et valorisation du réseau de fermes de références au sein du projet BV-LAC

    OpenAIRE

    Penot, E.

    2010-01-01

    L'approche " exploitation " a été récemment introduite dans les projets de développement de type BVPI, Bassin versant/périmètres irrigués, financés par AFD : en 2006 avec le projet pilote BV-lac I (au lac Alaotra) puis maintenue avec BVlac II depuis 2008. Cette approche privilégie la compréhension de la structure des exploitations agricoles et l'intégration des technologies à développer (nouveaux itinéraires technique ou améliorations organisationnelles du type accès au crédit ...) à travers ...

  7. Fanaroff-Riley I galaxies as the parent population of BL Lacertae objects. II - Optical constraints

    Energy Technology Data Exchange (ETDEWEB)

    Padovani, P.; Urry, C.M. (Space Telescope Science Institute, Baltimore, MD (USA))

    1991-02-01

    The hypothesis is investigated that BL Lacertae objects are a subset of Fanaroff-Riley (FR) I galaxies dominated by beamed emission from a relativistic jet aligned with the line of sight. It is found that FR I galaxies, although of low radio luminosity, are bright optical galaxies. If the beaming hypothesis is correct, the optical luminosity function of BL Lac objects, including the effect of the host galaxy, can be approximated by a double power law with a given differential index. New estimates of the number counts of BL Lac objects are made which constrain their local number density for L(B) greater than about 6 x 10 to the 43rd ergs/s to be in the range 110-720/cu Gpc. The corresponding ratio between the total number densities of BL Lac objects and FR I galaxies is 0.003 to 0.02. This limits the Lorentz factor of the optical emission to the range 8-20, larger than that of the X-ray emitting plasma and roughly of the same order as the radio Lorentz factor. 34 refs.

  8. 37 GHz observations of a large sample of BL Lacertae objects

    CERN Document Server

    Nieppola, E; Lähteenmäki, A; Valtaoja, E; Hakala, T; Hovatta, T; Kotiranta, M; Nummila, S; Ojala, T; Parviainen, M; Ranta, M; Saloranta, P -M; Torniainen, I; Tröller, M; 10.1086/512609

    2009-01-01

    We present 37 GHz data obtained at Metsahovi Radio Observatory in 2001 December - 2005 April for a large sample of BL Lacertae objects. We also report the mean variability indices and radio spectral indices in frequency intervals 5 - 37 GHz and 37 - 90 GHz. Approximately 34 % of the sample was detected at 37 GHz, 136 BL Lacertae objects in all. A large majority of the detected sources were low-energy BL Lacs (LBLs). The variability index values of the sample were diverse, the mean fractional variability of the sample being \\Delta S_2 = 0.31. The spectral indices also varied widely, but the average radio spectrum of the sample sources is flat. Our observations show that many of the high-energy BL Lacs (HBL), which are usually considered radio-quiet, can at times be detected at 37 GHz.

  9. Bistable behavior of the lac operon in E. coli when induced with a mixture of lactose and TMG

    Directory of Open Access Journals (Sweden)

    Orlando Díaz-Hernández

    2010-07-01

    Full Text Available In this work we investigate multistability in the lac operon of Escherichia coli when it is induced by a mixture of lactose and the non-metabolizable thiomethyl galactoside (TMG. In accordance with previously published experimental results and computer simulations, our simulations predict that: (1 when the system is induced by TMG, the system shows a discernible bistable behavior while, (2 when the system is induced by lactose, bistability does not disappear but excessively high concentrations of lactose would be required to observe it. Finally, our simulation results predict that when a mixture of lactose and TMG is used, the bistability region in the extracellular glucose concentration vs. extracellular lactose concentration parameter space changes in such a way that the model predictions regarding bistability could be tested experimentally. These experiments could help to solve a recent controversy regarding the existence of bistability in the lac operon under natural conditions.

  10. Narrative report May, June, July, August, 1963 Des Lacs National Wildlife Refuge, Lake Ilo National Wildlife Refuge, & Easement Refuges - District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from May through August of 1963. The report begins by summarizing the...

  11. Narrative report May, June, July, August, 1951 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge, Easement Refuges - District IV & 4a

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from May through August of 1951. The report begins by summarizing the...

  12. Narrative report January, February, March, April, 1962 Des Lacs National Wildlife Refuge, Lake Ilo National Wildlife Refuge, & Easement Refuges - District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge, Lake Ilo National Wildlife Refuge, and Easement Refuges - District IV outlines Refuge accomplishments...

  13. Narrative report May, June, July, August, 1950 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge, Easement Refuges - District IV & 4a

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from May through August of 1950. The report begins by summarizing the...

  14. Narrative report September, October, November, December, 1963 Des Lacs National Wildlife Refuge, Lake Ilo National Wildlife Refuge, & Easement Refuges - District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge, Lake Ilo National Wildlife Refuge, and Easement Refuges - District IV outlines Refuge accomplishments...

  15. Narrative report calendar year 1968 Des Lacs National Wildlife Refuge, Lake Ilo National Wildlife Refuge, White Lake National Wildlife Refuge, Pretty Rock Easement Refuge, & Stewart Lake Easement Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments during the 1968 calendar year. The report begins by summarizing...

  16. Narrative report May, June, July, August, 1962 Des Lacs National Wildlife Refuge, Lake Ilo National Wildlife Refuge, & Easement Refuges - District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge, Lake Ilo National Wildlife Refuge, and Easement Refuges - District IV outlines Refuge accomplishments...

  17. Narrative report May, June, July, August, 1955 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge & Easement Refuges - District IV & IVa

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from May through August of 1955. The report begins by summarizing the...

  18. The extent of co-metabolism of glucose and galactose by L. lactis changes with the expression of the lacSZ operon from Streptococcus thermophilus

    DEFF Research Database (Denmark)

    Solem, Christian; Købmann, Brian Jensen; Jensen, Peter Ruhdal

    2008-01-01

    The lactose transporter and β-galactosidase from Streptococcus thermophilus, encoded by the lacSZ operon, were introduced into the lactose-negative strain Lactococcus lactis MG1363 and the expression of the lacSZ operon was modulated by substitution of the native promoter with randomized synthetic...... promoters. A series of strains with various expression levels of lacSZ were examined for their fermentation of lactose. Strains with a high expression level were found to metabolize lactose in a similar manner to S. thermophilus, i.e. the galactose moiety of lactose was excreted to the growth medium...... and only glucose was metabolized in glycolysis. Interestingly, strains with low expression of the operon showed a mixed acid metabolism and co-metabolism of galactose and glucose. The lactose flux increased gradually with increasing expression of the lacSZ operon until an optimum was observed...

  19. Narrative report September, October, November, December, 1962 Des Lacs National Wildlife Refuge, Lake Ilo National Wildlife Refuge, and Easement Refuges - District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from September through December of 1962. The report begins by summarizing...

  20. Quarterly narrative report for Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, & Easement Refuges in District IV : August, September, October, 1940

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs topics include grazing. A progress report on field investigations and applied research is also provided. The public relations...

  1. Narrative report September, October, November, December, 1949 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, & Easement Refuges - District IV & 4a

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from September through December of 1949. The report begins by summarizing...

  2. Narrative report January, February, March, April, 1963 Des Lacs National Wildlife Refuge, Lake Ilo National Wildlife Refuge, & Easement Refuges - District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge, Lake Ilo National Wildlife Refuge, and Easement Refuges - District IV outlines Refuge accomplishments...

  3. Narrative report May, June, July, August, 1953 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, & Easement Refuges - District IV & 4a

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from May through August of 1953. The report begins by summarizing the...

  4. Narrative report January, February, March, April, 1954 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, & Easement Refuges - District IV & 4a

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from January through April of 1954. The report begins by summarizing the...

  5. Narrative report September, October, November, December, 1954 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, & Easement Refuges - District IV & 4a

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from September through December of 1954. The report begins by summarizing...

  6. Narrative report September, October, November, December, 1955 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge & Easement Refuges - District IV & 4a

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from September through December of 1955. The report begins by...

  7. Narrative report September, October, November, December, 1953 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, & Easement Refuges - District IV & 4a

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from September through December of 1953. The report begins by summarizing...

  8. Quarterly narrative report for Des Lacs Migratory Waterfowl Refuge, Lostwood Migratory Waterfowl Refuge, & Easement Refuges in District IV : February, March, April, 1940

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs topics include fur harvesting. A progress report on field investigations and applied research is also provided. The public...

  9. Quarterly narrative report : November, December, 1939, January, 1940 for Des Lacs Migratory Waterfowl Refuge, Lostwood Migratory Waterfowl Refuge, & Easement Refuges in District IV

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs & Lostwood Migratory Waterfowl Refuge outlines Refuge accomplishments from November 1939 through January of 1940. The report...

  10. Narrative report September, October, November, December, 1957 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge & Easement Refuges - District IV & IVa

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from September through December of 1957. The report begins by summarizing...

  11. Narrative report September, October, November, December, 1958 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge & Easement Refuges - District IV & IVa

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge, and Easement Refuges - District IV...

  12. Narrative report September, October, November, December, 1961 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Reufge, Lake Ilo National Wildlife Refuge, & Easement Refuges - District IV & IVa

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge, and Easement Refuges - District IV...

  13. Narrative report May, June, July, August, 1958 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge, & Easement Refuges - District IV & IVa

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge, and Easement Refuges - District IV...

  14. Narrative report January, February, March, April, 1960 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge, & Easement Refuges - District IV & IVa

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge, Lake Ilo National Wildlife Refuge, Lostwood National Wildlife Refuge, and Easement Refuges - District IV...

  15. Narrative report May, June, July, August, 1959 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge & Easement Refuges - District IV & IVa

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge, and Easement Refuges - District IV...

  16. Narrative report May, June, July, August, 1960 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge, & Easement Refuges - District IV & IVa

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo Naitonal Wildlife Refuge, and Easement Refuges - District IV...

  17. Narrative report May, June, July, August, 1961 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge, & Easement Refuges - District IV & IVa

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from May through August of 1961. The report begins by summarizing the...

  18. Narrative report January, February, March, April, 1957 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge, & Easement Refuges - District IV & IVa

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from January through April of 1957. The report begins by summarizing the...

  19. Narrative report January February, March, April, 1959 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge & Easement Refuges - District IV & IVa

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge, and Easement Refuges - District IV...

  20. Narrative report May, June, July, August, 1957 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge, & Easement Refuges - District IV & IVa

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs National Wildlife Refuge outlines Refuge accomplishments from May through August of 1957. The report begins by summarizing the...