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Sample records for bl lac 1es

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

    OpenAIRE

    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.

  2. 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 $\

  3. Observation of the BL Lac objects 1ES 1215+303 and 1ES 1218+304 with the MAGIC telescopes

    OpenAIRE

    Colin, Pierre; Gonzalez, Josefa Becerra; Lindfors, Elina; Lombardi, Saverio; Sitarek, Julian; Stamera, Antonio; collaboration, for the MAGIC

    2011-01-01

    The two BL Lac objects 1ES 1215+303 and 1ES 1218+304, separated by 0.8 deg, were observed with the MAGIC telescopes in 2010 and 2011. The 20 hours of data registered in January 2011 resulted in the first detection at Very High Energy (>100 GeV) of 1ES 1215+303 (also known as ON-325). This observation was triggered by a high optical state of the source reported by the Tuorla blazar monitoring program. Comparison with the 25 hours of data carried out from January to May 2010 suggests that 1ES 1...

  4. 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...

  5. 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...

  6. VERITAS results from a three-year observing campaign on the BL Lac object 1ES 0229+200

    CERN Document Server

    Cerruti, Matteo

    2013-01-01

    The BL Lac object 1ES 0229+200 is a firmly established very-high-energy (VHE; E >100 GeV) source. Located at a redshift of 0.1396, its published VHE spectrum is particularly hard (Gamma ~2.5) and is widely used to perform studies on the extragalactic background light (EBL) and the intergalactic magnetic field (IGMF). We present here the results of a long-term observing campaign on 1ES 0229+200 with VERITAS, lasting from 2009 to 2012, supported by multi-wavelength observations. We discuss the VERITAS results with a particular emphasis on the implications for the synchrotron-self-Compton modeling of the source emission and for the theoretical studies (especially on the intergalactic magnetic field) based on its VHE spectrum.

  7. 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...

  8. 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 ...

  9. 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.

  10. 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.

  11. 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 ...

  12. 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).

  13. 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).

  14. 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 ...

  15. 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...

  16. New extreme synchrotron BL Lac objects

    International Nuclear Information System (INIS)

    We report on the BeppoSAX observations of four 'extreme' BL Lacs, selected to have high synchrotron peak frequencies. All have been detected also in the PDS band. For 1ES 0120+340, PKS 0548-322 and H 2356-309 the spectrum is well fitted by a convex broken power-law, thus locating the synchrotron peak around 1-4 keV. 1ES 1426+428 presents a flat energy spectral index (αx=0.92) up to ∼100 keV, thus constraining the synchrotron peak to lie near or above that value. For their extreme properties, all sources could be strong TeV emitters

  17. Imaging Redshift Estimates for Fermi BL Lacs

    CERN Document Server

    Stadnik, Matt

    2014-01-01

    We have obtained WIYN and SOAR i' images of BL Lacertae objects (BL Lacs) and used these to detect or constrain the flux of the host galaxy. Under common standard candle assumptions these data provide estimates of, or lower bounds on, the redshift. Our targets are a set of flat-spectrum radio counterparts of high flux Fermi Large Area Telescope (LAT) sources, with sensitive spectral observations showing them to be continuum-dominated BL Lacs. In this sample 5 of 11 BL Lacs yielded significant host detections, with standard candle redshifts z=0.13-0.58. Our estimates and lower bounds are generally in agreement with other redshifts estimates, although our z=0.374 estimate for J0543-5532 implies a significantly sub-luminous host.

  18. 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.

  19. The RGB Sample of Intermediate BL Lacs

    CERN Document Server

    Laurent-Mühleisen, S A; Feigelson, E D; Brinkmann, W; Siebert, J

    1999-01-01

    Combining newly identified and previously known BL Lacs from the RASS-Green Bank (RGB) catalog, we present a sample of 127 BL Lacs, the largest ever derived from a single uniform survey. A Complete sample of 33 objects brighter than O=18.0 mag is also presented. These samples are compared to other known BL Lac samples and are generally found to exhibit properties intermediate between those of the previously disparate classes of High and Low energy peaked BL Lacs (HBLs and LBLs, respectively). This result is most dramatic in the distribution of the X-ray to radio logarithmic flux ratios, where the RGB BL Lacs are shown to peak precisely where the sharp dichotomy between the two subclasses was previously seen. The alpha_ro vs alpha_ox diagram also shows the RGB sample smoothly bridges the gap between the previously distinct subclasses of LBLs and HBLs. We also find a weak, but statistically significant correlation between the composite X-ray spectral index alpha_xox and alpha_ro. This implies that the more LBL-...

  20. Evolutionary behaviour of BL Lac objects

    OpenAIRE

    Beckmann, Volker

    1998-01-01

    We present analysis of a new flux limited sample of 72 X-ray selected BL Lacertae objects with known redshifts for 59 of them. We find the more X-ray dominated BL Lac having negative evolution with redshift, while intermediate objects show no evolution at all. X-ray dominated objects show higher X-ray luminosities and flatter X-ray spectra than the intermediate ones. We were also able to determine the redshift of 1517+656, which is part of our sample and is the optically most luminous X-ray s...

  1. 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...

  2. The fraction of BL Lac objects in groups of galaxies

    CERN Document Server

    Muriel, Hernán

    2016-01-01

    Context: BL Lac objects are a rare class of active galactic nuclei that typically show featureless optical spectra that make it difficult to estimate the redshift. A novel method for estimating the redshift of BL Lac objects has recently been proposed which assumes that these objects typically reside in groups of galaxies. Aims: The aim of this work is to estimate the fraction of BL Lac objects that reside in groups of galaxies. Methods: We use a sample of groups (M12 catalogue) selected by applying a friends-of-friends algorithm in the SDSS DR12. Galaxies in the M12 sample were cross-correlated with the sample of blazars in the BZCAT. Results: We found that 121 galaxies in the M12 catalogue are blazars in the BZCAT sample, all but one are BL Lac objects, and a large fraction are classified as BL Lac-galaxy dominated. Analysing the fraction of galaxies in groups as a function of redshift we have estimated a correction factor that takes into account the typical incompleteness of the catalogues based on the fri...

  3. Testing the blazar sequence with the least luminous BL Lacs

    CERN Document Server

    Raiteri, Claudia M

    2015-01-01

    In a previous paper, we proposed a new method to select low-power BL Lacs (LPBLs) based on mid-infrared emission and flux contrast through the Ca II spectral break; that study led to the selection of a complete sample formed by 34 LPBLs with 0.05BL Lacs. We find that the ratios between the X-ray and radio luminosities range from ~20 to ~30000 and that the synchrotron peak frequencies span a wide energy interval, from log(nu_peak)~13.5 to ~20 [Hz]. This indicates a broad variety of SED shapes and a mixture of BL Lac flavors. Indeed, although the majority of our LPBLs are high-energy peaked BL Lacs (HBLs), we find that a quarter of them are low-energy peaked BL Lacs (LBLs), despite the fact that the sample is biased against the selection of LBLs. The analysis of the median LPBL SED con...

  4. 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...

  5. A hadronic origin for ultra-high-frequency-peaked BL Lac objects

    CERN Document Server

    Cerruti, M; Boisson, C; Inoue, S

    2014-01-01

    Current Cherenkov telescopes have identified a population of ultra-high-frequency peaked BL Lac objects (UHBLs), also known as extreme blazars, that exhibit exceptionally hard TeV spectra, including 1ES 0229+200, 1ES 0347-121, RGB J0710+591, 1ES 1101-232, and 1ES 1218+304. Although one-zone synchrotron-self-Compton (SSC) models have been generally successful in interpreting the high-energy emission observed in other BL Lac objects, they are problematic for UHBLs, necessitating very large Doppler factors and/or extremely high minimum Lorentz factors of the emitting leptonic population. In this context, we have investigated alternative scenarios where hadronic emission processes are important, using a newly developed (lepto-)hadronic numerical code to systematically explore the physical parameters of the emission region that reproduces the observed spectra while avoiding the extreme values encountered in pure SSC models. Assuming a fixed Doppler factor $\\delta=30$, two principal parameter regimes are identified...

  6. Multi-wavelength studies of TeV γ-ray emitting BL Lac objects

    International Nuclear Information System (INIS)

    The discovery of TeV γ-ray emission of BL Lac objects gave new insights in the particle acceleration and the emission processes of the highly relativistic jets. To shed light on the conditions in the high energetic jets of the TeV γ-ray emitting BL Lac objects, I have studied in great detail the spectral energy distribution (SED) of sources with different characteristics. BL Lac objects with exceptional very high energy spectra (soft and hard spectra) and with large differences in the emission peak frequencies, to cover the different classes of BL Lac objects, have been chosen. The basic aim of this thesis was, to study with new, simultaneous multi- avelength (MWL) observations, if the emission processes of these extreme cases of TeV BL Lac objects can be explained by the synchrotron Self-Compton (SSC) model which is well established for the class of BL Lac objects at lower energies. We proposed MWL observations in the optical, UV and X-ray regime, to be conducted simultaneous to very high energy observations with the H.E.S.S. experiment, to study the emission processes. Simultaneous observations are crucial, since BL Lac objects are variable at all wavebands. I have analysed the MWL observations and conducted detailed variability and spectral studies in each wavelength range. The different kind of absorption at each wavelength as well as the influence of the host galaxy of the AGN has been considered to obtain the intrinsic jet spectrum. I have then applied the commonly used theoretical jet model, the SSC model, to the SED. I conducted a MWL campaign on a BL Lac object with the softest TeV spectrum, PKS 2005-489, during which it was observed in a very bright X-ray state. The good spectral coverage of the emission peaks allowed a detailed study of the SSC model. The extreme BL Lac object 1ES 0229+200 exhibits a hard intrinsic TeV spectrum. With my MWL campaign I found a clear cut-off in the optical range and therefore a high minimum Lorentz factor is needed to

  7. Properties of optically selected BL Lac candidates from the SDSS

    CERN Document Server

    Kügler, S D; Heidt, J; Esser, J; Schultz, T

    2014-01-01

    \\textbf{Context.} Deep optical surveys open the avenue for find large numbers of BL Lac objects that are hard to identify because they lack the unique properties classifying them as such. While radio or X-ray surveys typically reveal dozens of sources, recent compilations based on optical criteria alone have increased the number of BL Lac candidates considerably. However, these compilations are subject to biases and may contain a substantial number of contaminating sources. \\textbf{Aims.} In this paper we extend our analysis of 182 optically selected BL Lac object candidates from the SDSS with respect to an earlier study. The main goal is to determine the number of bona fide BL Lac objects in this sample. \\textbf{Methods.} We examine their variability characteristics, determine their broad-band radio-UV SEDs, and search for the presence of a host galaxy. In addition we present new optical spectra for 27 targets with improved S/N with respect to the SDSS spectra. \\textbf{Results.} At least 59% of our targets h...

  8. Imaging redshift estimates for Fermi BL Lac objects

    Energy Technology Data Exchange (ETDEWEB)

    Stadnik, Matt; Romani, Roger W., E-mail: mstadnik@stanford.edu, E-mail: rwr@astro.stanford.edu [Dept. of Physics/KIPAC, Stanford University, Stanford, CA 94305-4060 (United States)

    2014-04-01

    We have obtained WIYN and SOAR i' images of BL Lacertae objects and used these to detect or constrain the flux of the host galaxy. Under common standard candle assumptions, these data provide estimates of, or lower bounds on, the redshift. Our targets are a set of flat-spectrum radio counterparts of high flux Fermi Large Area Telescope sources, with sensitive spectral observations showing them to be continuum-dominated BL Lac objects. In this sample, 5 of 11 BL Lac objects yielded significant host detections, with standard candle redshifts z = 0.13-0.58. Our estimates and lower bounds are generally in agreement with other redshifts estimates, although our z = 0.374 estimate for J0543–5532 implies a significantly sub-luminous host.

  9. 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.

  10. 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.

  11. 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.

  12. A Large Sample of BL Lacs from SDSS and FIRST

    CERN Document Server

    Plotkin, Richard M; Hall, Patrick B; Margon, Bruce; Voges, Wolfgang; Schneider, Donald P; Stinson, Gregory; York, Donald G

    2008-01-01

    We present a large sample of 501 radio-selected BL Lac candidates from the combination of the Sloan Digital Sky Survey (SDSS) Data Release 5 optical spectroscopy and from the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) radio survey; this is one of the largest BL Lac samples yet assembled, and each object emerges with homogeneous data coverage. Each candidate is detected in the radio from FIRST and confirmed in SDSS optical spectroscopy to have: (1) no emission feature with measured rest equivalent width larger than 5 Angstroms; and (2) no measured Ca II H/K depression larger than 40%. We subdivide our sample into 426 higher confidence candidates and 75 lower confidence candidates. We argue that contamination from other classes of objects that formally pass our selection criteria is small, and we identify a few very rare radio AGN with unusual spectra that are probably related to broad absorption line quasars. About one-fifth of our sample were known BL Lacs prior to the SDSS. A preliminary ana...

  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. 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...

  15. 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.

  16. 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

  17. 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\\,{\

  18. 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...

  19. 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.

  20. 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...

  1. A search of CO emission lines in blazars: the low molecular gas content of BL Lac objects compared to quasars

    Science.gov (United States)

    Fumagalli, Michele; Dessauges-Zavadsky, Miroslava; Furniss, Amy; Prochaska, J. Xavier; Williams, David A.; Kaplan, Kyle; Hogan, Matthew

    2012-08-01

    BL Lacertae (Lac) objects that are detected at very high energies (VHE) are of fundamental importance to study multiple astrophysical processes, including the physics of jets, the properties of the extragalactic background light and the strength of the intergalactic magnetic field. Unfortunately, since most blazars have featureless optical spectra that preclude a redshift determination, a substantial fraction of these VHE extragalactic sources cannot be used for cosmological studies. To assess whether molecular lines are a viable way to establish distances, we have undertaken a pilot programme at the Institut of Millimétrique (IRAM) 30 m telescope to search for CO lines in three BL Lac objects with known redshifts. We report a positive detection of 12 MH_2 ˜ 3 × 10>8 M⊙ towards 1ES 1959+650, but due to the poor quality of the baseline, this value is affected by a large systematic uncertainty. For the remaining two sources, W Comae and RGB J0710+591, we derive 3σ upper limits at, respectively, H2 conversion factor α = 4 M⊙ (K km s-1 pc2)-1. If these low molecular gas masses are typical for blazars, blind redshift searches in molecular lines are currently unfeasible. However, deep observations are still a promising way to obtain precise redshifts for sources whose approximate distances are known via indirect methods. Our observations further reveal a deficiency of molecular gas in BL Lac objects compared to quasars, suggesting that the host galaxies of these two types of active galactic nuclei (AGN) are not drawn from the same parent population. Future observations are needed to assess whether this discrepancy is statistically significant, but our pilot programme shows how studies of the interstellar medium in AGN can provide key information to explore the connection between the active nuclei and the host galaxies. Based on observations carried out with the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).

  2. Multiband optical polarimetry of BL Lac objects with the Nordic Optical Telescope

    CERN Document Server

    Tommasi, L; Pian, E; Piirola, V; Poretti, E; Scaltriti, F; Sillanpää, A; Takalo, L; Treves, A

    2001-01-01

    Optical polarization of seven selected BL Lac objects in UBVRI bands was studied with the Nordic Optical Telescope from December 10-14, 1999. Two of them, 3C 66A and PKS 0735+178, were monitored for 4 nights for a total integration time of 4.75 and 5.5 hours, respectively. Other objects (1Jy 0138-097, H 0414+009, PKS 0823-223, OJ287 and BL Lac) were observed sparsely during the run. Apart from PKS 0823-223 (more polarized than observed in the past), the sources show levels of flux and polarization consistent with results at previous epochs. 3C 66A and PKS 0735+178 were intensively observed during December 11 and 12 and exhibited variability of polarization, both on internight and intranight time scales. Wavelength dependence of polarization has been investigated, as well as circular polarization. The results are discussed within the standard model for BL Lacs.

  3. A search of CO emission lines in blazars: the low molecular gas content of BL Lac objects compared to quasars

    CERN Document Server

    Fumagalli, Michele; Furniss, Amy; Prochaska, J Xavier; Williams, David; Kaplan, Kyle; Hogan, Matthew

    2012-01-01

    BL Lacertae (Lac) objects that are detected at very-high energies (VHE) are of fundamental importance to study multiple astrophysical processes, including the physics of jets, the properties of the extragalactic background light and the strength of the intergalactic magnetic field. Unfortunately, since most blazars have featureless optical spectra that preclude a redshift determination, a substantial fraction of these VHE extragalactic sources cannot be used for cosmological studies. To assess whether molecular lines are a viable way to establish distances, we have undertaken a pilot program at the IRAM 30m telescope to search for CO lines in three BL Lac objects with known redshifts. We report a positive detection of M_H2 ~ 3x10^8 Msun toward 1ES 1959+650, but due to the poor quality of the baseline, this value is affected by a large systematic uncertainty. For the remaining two sources, W Comae and RGB J0710+591, we derive 3sigma upper limits at, respectively, M_H2 < 8.0x10^8 Msun and M_H2 < 1.6x10^9 ...

  4. 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 $\

  5. The colours of BL Lac objects: a new approach to their classification

    CERN Document Server

    Massaro, Enrico; Piranomonte, Silvia

    2012-01-01

    We selected a sample of 437 BL Lac objects, taken from the RomaBZCat catalogue, for which spectroscopic information and SDSS photometry is available. We propose a new classification of BL Lacs in which the sources' type is not defined only on the basis of the peak frequency of the synchrotron component in their Spectral Energy Distribution (types L and H), but also on the relevance of this component with respect to the brightness of the host galaxy (types N and G, for nuclear or galaxy dominated sources). We found that the SDSS colour index u-r=1.4 is a good separator between these two types. We used multiband colour-colour plots to study the properties of the BL Lac classes and found that in the X-ray to radio flux ratio vs u-r plot most of the N (blue) sources are located in a rather narrow strip, while the G-sources (red) are spread in a large area, and most of them are located in galaxy clusters or interacting systems, suggesting that their X-ray emission is not from a genuine BL Lac nucleus but it is rel...

  6. 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).

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

    NARCIS (Netherlands)

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

    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 -

  9. 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

  10. 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 -

  11. 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.

  12. Simultaneous Multifrequency Observations of the BL Lac MS 0205.7+3509

    CERN Document Server

    Watson, D; McBreen, B; Smith, N; Tashiro, M; Foley, A R; Metcalfe, L; Beckmann, V; Sánchez, S F; Teraesranta, H

    1999-01-01

    Radio and optical observations of the possible microlensed BL Lac source MS 0205.7+3509 were obtained simultaneously with ASCA x-ray measurements in February 1997. A single power law model, with a photon index of 2.61, is an adequate fit to the ASCA data, once hydrogenic absorption in excess of the Galactic value is permitted, confirming a previous ROSAT measurement. On the basis of our simultaneous data we have determined MS 0205.7+3509 to be a typical x--ray selected BL Lac, with alpha_xox=-0.82. There is no indication of an inverse Compton (IC) component in the ASCA spectrum up to 10 keV. No evidence for variability on hour-long timescales is present in either the x-ray or the optical data. We discuss these results in the context of a gravitational microlensing scenario for MS 0205.7+3509.

  13. BeppoSAX Spectral Survey of BL Lacs - new spectra and results

    OpenAIRE

    Beckmann, V.; Wolter, A.; Celotti, A.; Costamante, L.; Ghisellini, G.; Maccacaro, T.; Tagliaferri, G.

    2001-01-01

    We present BeppoSAX LECS, MECS, and PDS spectra of eleven X-ray selected BL Lacertae objects. Combining these sources with the ones presented elsewhere we have a sample of 21 BL Lacs from the Einstein Medium Sensitivity and Einstein Slew Survey. The sample shows strong correlations of several physical parameters with the peak frequency of the synchrotron branch of the spectral energy distribution. In particular the peak frequency is correlated to the X-ray spectral shape: objects with the pea...

  14. 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.

  15. 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...

  16. The stellar content of low redshift BL Lac host galaxies from multicolour imaging

    Directory of Open Access Journals (Sweden)

    T. Hyvönen

    2008-01-01

    Full Text Available Presentamos imágenes en las bandas UBV de 18 objetos BL Lac de bajo corrimiento al rojo (z ≤ 0.3. Estos datos se usan para investigar los colores rojo-azul-infrarrojo y gradientes de color de galaxias huésped. La distribución del color integrado azul/cercano-infrarrojo y el gradiente de color de las galaxias huésped de objetos BL Lac es más amplia que la que tienen las elípticas no-activas, y la mayoría de los objetos BL Lac tienen galaxias huésped más azules y gradientes de color más empinados que los de las elípticas no-activas. Los colores azules parecen ser causados por una componente de la población estelar joven, e indican una conexión entre la formación estelar causada por un evento de interacción/fusión, y el encendido de la actividad nuclear. Este resultado es apoyado por los modelos de población estelar, que indican que existe una población estelar joven/intermedia en la mayoría de los objetos de la muestra.

  17. 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 ...

  18. 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...

  19. 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.

  20. The Connection among Gamma-ray Burst Host-Galaxies, BL Lacs and Quasars

    OpenAIRE

    Rej, A.

    1999-01-01

    A possible connection among host-galaxies of gamma-ray bursts, BL Lacs and quasars is analysed. It is believed that the gamma-ray bursts, which do not show radio or infrared emission, occur in faint blue dwarf galaxies, that are seen around radio-quiet quasars, which lie in clusters. The GRB counterparts, which show radio emission, may be associated with more evolved starbursting environments, and arise from red galaxies, that are observed around some radio-loud quasars lying in richer cluste...

  1. Black hole mass and binary model for BL Lac object OJ 287

    OpenAIRE

    Liu, F. K.; Wu, Xue-Bing

    2002-01-01

    Recent intensive observations of the BL Lac object OJ 287 raise a lot of questions on the models of binary black holes, processing jets, rotating helical jets and thermal instability of slim accretion disks. After carefully analyzing their radio flux and polarization data, Valtaoja et al. (\\cite{valtaoja00}) propose a new binary model. Based on the black hole mass of $4 \\times 10^8 {\\rm M_\\odot}$ estimated with the tight correlations of the black hole masses and the bulge luminosity or centra...

  2. 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).

  3. 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.

  4. An Analysis of Periodic Components in BL Lac Object S5 0716 +714 with MUSIC Method

    Science.gov (United States)

    Tang, J.

    2012-01-01

    Multiple signal classification (MUSIC) algorithms are introduced to the estimation of the period of variation of BL Lac objects.The principle of MUSIC spectral analysis method and theoretical analysis of the resolution of frequency spectrum using analog signals are included. From a lot of literatures, we have collected a lot of effective observation data of BL Lac object S5 0716 + 714 in V, R, I bands from 1994 to 2008. The light variation periods of S5 0716 +714 are obtained by means of the MUSIC spectral analysis method and periodogram spectral analysis method. There exist two major periods: (3.33±0.08) years and (1.24±0.01) years for all bands. The estimation of the period of variation of the algorithm based on the MUSIC spectral analysis method is compared with that of the algorithm based on the periodogram spectral analysis method. It is a super-resolution algorithm with small data length, and could be used to detect the period of variation of weak signals.

  5. 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.

  6. 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.

  7. 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.

  8. Contemporaneous Broadband Observations of Three High-Redshift BL Lac Objects

    OpenAIRE

    Ackermann, Markus; Ajello, M.; J. Bregeon(c); Troja, E.; G. Vianello; Wood, K. S.; Wood, M; Fermi-LAT Collaboration; Britto, R. J.; Bruel, P.; Buehler, R.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.

    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\\quad \\gtrsim $ 1.239), and 3FGL J0811.2−7529 (z = 0.774), detected by Fermi with relatively flat gigaelectronvolt spectra. By observing simultaneously in the near-infrared 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 r...

  9. The physical properties of Fermi TeV BL Lac objects jets

    Science.gov (United States)

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

    2016-09-01

    We investigate the physical properties of Fermi TeV BL Lac objects jets by modeling 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 Thomson regime. (ii) There are negative correlations between νsy and r, the νIC and r, which is a signature of the energy-dependence 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-dependence 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 sub-sample 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 the change/evolution of electron energy distribution may be mainly responsible for the flux variation.

  10. 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.

  11. 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...

  12. Evidence for VHE Gamma-ray Emission from the Distant BL Lac PG 1553+113

    CERN Document Server

    Aharonian, F; Bazer-Bachi, A R; Beilicke, M; Benbow, W; Berge, D; Bernlöhr, K; Boisson, C; Bolz, O; Borrel, V; Braun, I; Breitling, F; Brown, A M; Buhler, R; Carrigan, S; Chadwick, P M; Chounet, L M; Cornils, R; Costamante, L; Degrange, B; Dickinson, H J; Djannati-Ata, A; O'Connor-Drury, L; Dubus, G; Egberts, K; Emmanoulopoulos, D; Espigat, P; Feinstein, F; Fontaine, G; Funk, S; Gallant, Y A; Giebels, B; Glicenstein, J F; Goret, P; Hadjichristidis, C; Hauser, D; Hauser, M; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hofmann, W; Holleran, M; Horns, D; Jacholkowska, A; De Jager, O C; Khelifi, B; Komin, Nu; Konopelko, A; Latham, I J; Le Gallou, R; Lemiere, A; Lemoine-Goumard, M; Lohse, T; Martin, J M; Martineau-Huynh, O; Marcowith, A; Masterson, C; McComb, T J L; De Naurois, Mathieu; Nedbal, D; Nolan, S J; Noutsos, A; Orford, K J; Osborne, J L; Ouchrif, M; Panter, M; Pelletier, G; Pita, S; Pühlhofer, G; Punch, M; Raubenheimer, B C; Raue, M; Rayner, S M; Reimer, A; Reimer, O; Ripken, J; Rob, L; Rolland, L; Rowell, G; Sahakian, V V; Sauge, L; Schlenker, S; Schlickeiser, R; Schuster, C; Schwanke, U; Siewert, M; Sol, H; Spangler, D; Steenkamp, R; Stegmann, C; Superina, G; Tavernet, J P; Terrier, R; Theoret, C G; Tluczykont, M; Van Eldik, C; Vasileiadis, G; Venter, C; Vincent, P; Völk, H J; Wagner, S J; Ward, M

    2006-01-01

    The high-frequency peaked BL Lac PG 1553+113 was observed in 2005 with the H.E.S.S. stereoscopic array of imaging atmospheric-Cherenkov telescopes in Namibia. Using the H.E.S.S. standard analysis, an excess was measured at the 4.0 sigma level in these observations (7.6 hours live time). Three alternative, lower-threshold analyses yield >5 sigma excesses. The observed integral flux above 200 GeV is (4.8 +/- 1.3_{stat} +/- 1.0_{syst}) x10^{-12} cm^{-2} s^{-1}, and shows no evidence for variability. The measured energy spectrum is characterized by a very soft power law (photon index of Gamma=4.0 +/- 0.6). Although the redshift of PG 1553+113 is unknown, there are strong indications that it is greater than z=0.25 and possibly larger than z=0.78. The observed spectrum is interpreted in the context of VHE gamma-ray absorption by the Extragalactic Background Light, and is used to place an upper limit on the redshift of z<0.74.

  13. 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 \

  14. Black hole mass and binary model for BL Lac object OJ 287

    CERN Document Server

    Liu, F K; Wu, Xue-Bing

    2002-01-01

    Recent intensive observations of the BL Lac object OJ 287 raise a lot of questions on the models of binary black holes, processing jets, rotating helical jets and thermal instability of slim accretion disks. After carefully analyzing their radio flux and polarization data, Valtaoja et al. (\\cite{valtaoja00}) propose a new binary model. Based on the black hole mass of $4 \\times 10^8 {\\rm M_\\odot}$ estimated with the tight correlations of the black hole masses and the bulge luminosity or central velocity dispersion of host galaxies, we computed the physical parameters of the new binary scenario. The impact of the secondary on the accretion disk around the primary black hole causes strong shocks propagating inwards and outwards, whose arrival at the jet roots is identified with the rapid increase of optical polarization and the large change of polarization angle at about 0.30 yr after the first main optical flare. An increase of optical polarization, a large rotation of positional angle and a small synchrotron f...

  15. 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...

  16. 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...

  17. 3C84, BL Lac. Earth based VLBI test for the RADIOASTRON project

    CERN Document Server

    Chuprikov, Andrey; Chibisov, Andrey; Kostenko, Vladimir; Kovalev, Yuri; Graham, Dave; Lobanov, Andrew; Giovannini, Gabriele

    2011-01-01

    Results of processing of data of a VLBI experiment titled RAPL01 are presented. These VLBI observations were made on 4th February, 2010 at 6.28 cm between the 100-m antenna of the Max Planck Institute (Effelsberg, Germany), Puschino 22-m antenna (Astro Space Center (ASC), Russia), and two 32-m antennas of the Istituto di Radioastronomia di Bologna (Bologna, Italy) in Noto and Medicina. 2 well-known sources, 3C84 (0316+413), and BL Lac (2200+420) were included in the schedule of observations. Each of them was observed during 1 hour at all the stations. The Mark-5A registration system was used at 3 European antennae. The alternative registration system known as RDR (RADIOASTRON Data Recorder) was used in Puschino. The Puschino data were recorded in format RDF (RADIOASTRON Data Format). Two standard recording modes designed as 128-4-1 (one bit), and 256-4-2 (two bit) were used in the experiment. All the Mark-5A data from European antennae were successfully converted into the RDF format. Then, the correlation fun...

  18. ERRATIC FLARING OF BL LAC IN 2012–2013: MULTIWAVELENGTH OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Wehrle, Ann E. [Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301 (United States); Grupe, Dirk [Space Science Center, Morehead State University, 235 Martindale Drive, Morehead, KY 40351 (United States); Jorstad, Svetlana G.; Marscher, Alan P. [Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Gurwell, Mark [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA-02138 (United States); Baloković, Mislav; Hovatta, Talvikki; Harrison, Fiona H. [Cahill Center for Astronomy and Astrophysics, Caltech, Pasadena, CA 91125 (United States); Madejski, Grzegorz M. [Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Stern, Daniel, E-mail: awehrle@spacescience.org [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2016-01-10

    BL Lac, the eponymous blazar, flared to historically high levels at millimeter, infrared, X-ray, and gamma-ray wavelengths in 2012. We present observations made with Herschel, Swift, NuSTAR, Fermi, the Submillimeter Array, CARMA, and the VLBA in 2012–2013, including three months with nearly daily sampling at several wavebands. We have also conducted an intensive campaign of 30 hr with every-orbit observations by Swift and NuSTAR, accompanied by Herschel, and Fermi observations. The source was highly variable at all bands. Time lags, correlations between bands, and the changing shapes of the spectral energy distributions can be explained by synchrotron radiation and inverse Compton emission from nonthermal seed photons originating from within the jet. The passage of four new superluminal very long baseline interferometry knots through the core and two stationary knots about 4 pc downstream accompanied the high flaring in 2012–2013. The seed photons for inverse Compton scattering may arise from the stationary knots and from a Mach disk near the core where relatively slow-moving plasma generates intense nonthermal radiation. The 95 spectral energy distributions obtained on consecutive days form the most densely sampled, broad wavelength coverage for any blazar. The observed spectral energy distributions and multi-waveband light curves are similar to simulated spectral energy distributions and light curves generated with a model in which turbulent plasma crosses a conical shock with a Mach disk.

  19. 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.

  20. 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...

  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. New detection of high-energy gamma-ray sources associated with BL Lac objects above 10 GeV

    CERN Document Server

    Campana, R; Bernieri, E

    2015-01-01

    We report the detection of 19 new high-energy gamma-ray sources closely associated with BL Lac objects at energies higher than 10 GeV in the 6.3 years Fermi-Large Area Telescope sky, selected using the Minimum Spanning Tree (MST) clustering method. Photon clusters with good selection parameters were found matching the positions of known blazars in the fifth Roma-BZCAT catalogue. A brief summary of the properties of these sources is presented.

  3. 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.

  4. Baryon Loading Efficiency and Particle Acceleration Efficiency of Relativistic Jets: Cases for Low Luminosity BL Lacs

    Science.gov (United States)

    Inoue, Yoshiyuki; Tanaka, Yasuyuki T.

    2016-09-01

    Relativistic jets launched by supermassive black holes, so-called active galactic nuclei (AGNs), are known as the most energetic particle accelerators in the universe. However, the baryon loading efficiency onto the jets from the accretion flows and their particle acceleration efficiencies have been veiled in mystery. With the latest data sets, we perform multi-wavelength spectral analysis of quiescent spectra of 13 TeV gamma-ray detected high-frequency-peaked BL Lacs (HBLs) following one-zone static synchrotron self-Compton (SSC) model. We determine the minimum, cooling break, and maximum electron Lorentz factors following the diffusive shock acceleration (DSA) theory. We find that HBLs have {P}B/{P}e˜ 6.3× {10}-3 and the radiative efficiency {ɛ }{{rad,jet}}˜ 6.7× {10}-4, where P B and P e is the Poynting and electron power, respectively. By assuming 10 leptons per one proton, the jet power relates to the black hole mass as {P}{{jet}}/{L}{{Edd}}˜ 0.18, where {P}{{jet}} and {L}{{Edd}} is the jet power and the Eddington luminosity, respectively. Under our model assumptions, we further find that HBLs have a jet production efficiency of {η }{{jet}}˜ 1.5 and a mass loading efficiency of {ξ }{{jet}}≳ 5× {10}-2. We also investigate the particle acceleration efficiency in the blazar zone by including the most recent Swift/BAT data. Our samples ubiquitously have particle acceleration efficiencies of {η }g˜ {10}4.5, which is inefficient to accelerate particles up to the ultra-high-energy-cosmic-ray (UHECR) regime. This implies that the UHECR acceleration sites should not be the blazar zones of quiescent low power AGN jets, if one assumes the one-zone SSC model based on the DSA theory.

  5. 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.

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

    OpenAIRE

    Chandra, Sunil; Zhang, Haocheng; 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 promi...

  7. 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).

  8. 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...

  9. Discovery of VHE gamma-rays from the high-frequency-peaked BL Lac object RGB J0152+017

    CERN Document Server

    Aharonian, F; Barresde Almeida, U; Bazer-Bachi, A R; Behera, B; Beilicke, M; Benbow, W; Bernlöhr, K; Boisson, C; Borrel, V; Braun, I; Brion, E; Brucker, J; Buhler, R; Bulik, T; Büsching, I; Boutelier, T; Carrigan, S; Chadwick, P M; Chaves, R C G; Chounet, L M; Clapson, A C; Coignet, G; Cornils, R; Costamante, L; Dalton, M; Degrange, B; Dickinson, H J; Djannati-Ata, A; Domainko, i 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; Fuling, M; Gabici, S; 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; Kaufmann, S; Kendziorra, E; Kerschhaggl, M; Khelifi, B; Keogh, D; Komin, Nu; Kosack, K; Lamanna, G; Latham, I J; Lenain, J P; Lohse, D Khangulyan T; Martin, J M; Martineau-Huynh, O; Marcowith, A; Masterson, C; Maurin, D; McComb, T J L; Moderski, R; Moulin, E; Naumann-Godo, M; De Naurois, Mathieu; Nedbal, D; Nekrassov, 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; Quirrenbach, Andreas G; Raubenheimer, B C; Raue, M; Rayner, S M; Renaud, M; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Ruppel, J; Sahakian, V V; Santangelo, A; Schlickeiser, R; Schock, F M; 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

    2008-01-01

    Aims: The BL Lac object RGB J0152+017 (z=0.080) was predicted to be a very high-energy (VHE; > 100 GeV) gamma-ray source, due to its high X-ray and radio fluxes. Our aim is to understand the radiative processes by investigating the observed emission and its production mechanism using the High Energy Stereoscopic System (H.E.S.S.) experiment. Methods: We report recent observations of the BL Lac source RGB J0152+017 made in late October and November 2007 with the H.E.S.S. array consisting of four imaging atmospheric Cherenkov telescopes. Contemporaneous observations were made in X-rays by the Swift and RXTE satellites, in the optical band with the ATOM telescope, and in the radio band with the Nancay Radio Telescope. Results: A signal of 173 gamma-ray photons corresponding to a statistical significance of 6.6 sigma was found in the data. The energy spectrum of the source can be described by a powerlaw with a spectral index of 2.95+/-0.36stat+/-0.20syst. The integral flux above 300 GeV corresponds to ~2% of the ...

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. On the Absence of Core Luminosity–Core-Dominance Parameter (C - ) Correlation in Radio Galaxies and BL Lacs

    Indian Academy of Sciences (India)

    J. A. Alhassan; A. A. Ubachukwu; F. C. Odo

    2013-03-01

    We have presented an alternative interpretation for the absence of correlation in the relationship between the core radio power (C) and core-dominance parameter () for a sample of BL Lacs and radio galaxies found in Fan & Zhang (Astron. Astrophys. 407, 899 (2003)). This is contrary to the predictions of the relativistic beaming and radio source orientation models in which the core luminosity is expected to be Doppler-boosted relative to the extended luminosity which is generally assumed to be isotropic. Our analysis of the C - data indicates a strong luminosity selection effect (reminiscent of bright source samples due to Malmquist bias) in the sample. In particular, we showed that a strong C - correlation exists above some redshift cut-off which may correspond to the flux limit of the sample used.

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

    Science.gov (United States)

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

    2016-06-01

    We report on the 1.6 GHz (18 cm) very long baseline interferometry (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 ≳ 1.8× {10}9 K, which is typical for low-luminosity blazars in general. Overall, the 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 because HESS J1943+213 does not reveal any optical or infrared signatures of the active galactic nucleus activity, it would never be recognized and identified as a BL Lac object if not for its location close to the Galactic plane where the High Energy Stereoscopic System surveyed for and the follow-up dedicated X-ray and radio studies triggered by the source detection in the TeV range. Our results suggest, therefore, a presence of an unrecognized, possibly very numerous population of particularly extreme HBLs and simultaneously demonstrate that the low-frequency VLBI observations with high angular resolution are indispensable for a proper identification of such objects.

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

    OpenAIRE

    Giommi, P.; Ghisellini, G.; Padovani, P.; Tagliaferri, G.

    2000-01-01

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

  17. VizieR Online Data Catalog: Multiwavelength obs. of BL Lac in 2012-2013 (Wehrle+, 2016)

    Science.gov (United States)

    Wehrle, A. E.; Grupe, D.; Jorstad, S. G.; Marscher, A. P.; Gurwell, M.; Balokovic, M.; Hovatta, T.; Madejski, G. M.; Harrison, F. H.; Stern, D.

    2016-03-01

    Our Herschel target of opportunity observations began on 2012 October 29 (MJD 56229) and continued for the three-month visibility window. We arranged for daily Swift pointings starting on 2012 October 27 through 2013 February 1. We also arranged for two intense periods of every-orbit Swift monitoring on 2012 December 11-12 and 2013 January 11-12. We obtained target of opportunity observations with NuSTAR on 2012 December 11-12. Observations of BL Lac every two to four days were carried out at the SMA on Mauna Kea, HI during the Herschel observation window, and intermittently thereafter. Monitoring observations with CARMA at 3mm were already underway. VLBA monitoring continued throughout the time range reported here as part of the ongoing Boston University (BU) γ-ray blazar monitoring program. Observations at other wavebands were already underway by other collaborations, e.g., the Whole Earth Blazar Telescope. In addition, roughly weekly Swift observations have been carried out for several years by A. Falcone and M. Stroh (Stroh & Falcone 2013ApJS..207...28S). Herschel SPIRE and PACS FIR observations of BL Lac are presented in table 1 and sections 2.2 and 2.5. SMA millimeter and submillimeter observations are presented in tables 1, 2 and 3 and sections 2.3 and 2.5. Millimeter observations with CARMA are presented in table 4 and sections 2.4 and 2.5. Swift optical, UV and X-ray observations are presented in tables 5 and 6 and section 2.6. Hard X-ray observations with NuSTAR are presented in section 2.7. γ-ray observations with Fermi are presented in section 2.8. The 7mm band observations are presented in section 2.9. The BU group obtained 2.4-10keV X-ray fluxes with the RXTE PCA three times per week from 2005 March 3 to 2011 December 31; see table 10 and Appendix. (7 data files).

  18. 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 ...

  19. 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...

  20. 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 $\

  1. Are both BL Lacs and pulsar wind nebulae the astrophysical counterparts of IceCube neutrino events?

    CERN Document Server

    Padovani, P

    2014-01-01

    IceCube has recently reported the discovery of high-energy neutrinos of astrophysical origin. These are the highest energy particles produced in cosmic ray interactions ever detected, opening up the possibility of investigating the PeV (10^15 eV) sky. Because of their rather large positional uncertainties, these events have so far not been associated to any astrophysical source. We have found plausible counterparts in the GeV - TeV band by using joint spatial and energetic information. Namely, we looked for sources in the available high-energy gamma-ray catalogues (TeVCat, WHSP, 1FHL) within the median error circles of the IceCube events. We then built the spectral energy distribution of these sources and compared it with the energy and flux of the corresponding neutrino events. The likely counterparts include "classic" BL Lacs, such as MKN 421 and PG 1553+113, as well as Galactic pulsar wind nebulae, namely MGRO J1908+06 and HESS J1809-193. This might indicate the emerging of a mixed scenario of Galactic and...

  2. 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...

  3. 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...

  4. 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...

  5. 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).

  6. 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).

  7. 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.

  8. 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 ...

  9. 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.

  10. 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).

  11. X-ray variability and prediction of TeV emission in the HBL 1ES1101-232

    OpenAIRE

    Wolter, A.; Tavecchio, F.; Caccianiga, A.; Ghisellini, G.; Tagliaferri, G.

    2000-01-01

    1ES1101-232 is a bright BL Lac of the High frequency peak class. We present here the results of two BeppoSAX observations in which the source has shown a variation of about 30% in flux with a corresponding spectral variability. We interpret the overall spectral energy distribution in terms of an homogeneous SSC model and, by using also the TeV upper limit from a short Mark 6 pointing, derive constraints on the physical parameters of the source, in particular on the magnetic field strength. Th...

  12. 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.

  13. 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...

  14. 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 ...

  15. First NuSTAR observations of the BL Lac - type blazar PKS~2155-304: constraints on the jet content and distribution of radiating particles

    CERN Document Server

    Madejski, G M; Madsen, K K; Chiang, J; Baloković, M; Paneque, D; Furniss, A K; Hayashida, M; Urry, C M; Sikora, M; Ajello, M; Blandford, R D; Harrison, F A; Sanchez, D; Giebels, B; Stern, D; Alexander, D M; Barret, D; Boggs, S E; Christensen, F E; Craig, W W; Forster, K; Giommi, P; Grefenstette, B; Hailey, C; Hornstrup, A; Kitaguchi, T; Koglin, J E; Mao, P H; Miyasaka, H; Mori, K; Perri, M; Pivovaroff, M J; Puccetti, S; Rana, V; Westergaard, N J; Zhang, W W; Zoglauer, A

    2016-01-01

    We report the first hard X-ray observations with NuSTAR of the BL Lac type blazar PKS 2155-304, augmented with soft X-ray data from XMM-Newton and gamma-ray data from the Fermi Large Area Telescope, obtained in April 2013 when the source was in a very low flux state. A joint NuSTAR and XMM spectrum, covering the energy range 0.5 - 60 keV, is best described by a model consisting of a log-parabola component with curvature beta = 0.3(+0.2,-0.1) and a (local) photon index 3.04 +/- 0.15 at photon energy of 2 keV, and a hard power-law tail with photon index 2.2 +/- 0.4. The hard X-ray tail can be smoothly joined to the quasi-simultaneous gamma-ray spectrum by a synchrotron self-Compton component produced by an electron distribution with index p = 2.2. Assuming that the power-law electron distribution extends down to the minimum electron Lorentz factor gamma_min = 1 and that there is one proton per electron, an unrealistically high total jet power L_p of roughly 10^47 erg/s is inferred. This can be reduced by two or...

  16. 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...

  17. 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...

  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. High-energy emitting BL Lacs and high-energy neutrinos - Prospects for the direct association with IceCube and KM3NeT

    CERN Document Server

    Righi, Chiara; Guetta, Dafne

    2016-01-01

    The origin of the high-energy flux of neutrinos detected by IceCube is still unknown. Recent works report the evidence for a possible positional correlation between the reconstructed neutrino arrival directions and the positions in the sky of low power, high-energy emitting BL Lac objects (HBL). Assuming that $\\gamma$-ray emitting HBL form the bulk of the sources of high-energy neutrinos above 100 TeV, we intend to calculate the number of events expected to be detected for each source by IceCube and KM3NeT. Based on a simple theoretically-motivated framework inspired by the structured jet scenario for these sources, we postulate a direct proportionality between high-energy $\\gamma$-ray and neutrino fluxes. We calculate the expected neutrino event rate for the HBL sources of the Second Fermi-LAT Catalog of High-Energy Sources (2FHL) for IceCube and the presently under construction KM3NeT using declination-dependent and exposure-weighted effective areas. We provide a list of 2FHL HBL with the calculated number ...

  20. 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...

  1. Application of the MST clustering to the high energy γ-ray sky. I—New possible detection of high-energy γ-ray emission associated with BL Lac objects

    Science.gov (United States)

    Campana, R.; Massaro, E.; Bernieri, E.; D'Amato, Q.

    2015-12-01

    In this paper we show an application of the Minimum Spanning Tree (MST) clustering method to the high-energy γ-ray sky observed at energies higher than 10 GeV in 6.3 years by the Fermi-Large Area Telescope. We report the detection of 19 new high-energy γ-ray clusters with good selection parameters whose centroid coordinates were found matching the positions of known BL Lac objects in the 5th Edition of the Roma-BZCAT catalogue. A brief summary of the properties of these sources is presented.

  2. Multiwavelength observations and modeling of 1ES 1959+650 in a low flux state

    CERN Document Server

    Aliu, E; Arlen, T; Aune, T; Beilicke, M; Benbow, W; Bird, R; Boettcher, M; Bouvier, A; Bugaev, V; Byrum, K; Cesarini, A; Ciupik, L; Collins-Hughes, E; Connolly, M P; Cui, W; Dickherber, R; Duke, C; Dumm, J; Errando, M; Falcone, A; Federici, S; Feng, Q; Finley, J P; Finnegan, G; Fortson, L; Furniss, A; Galante, N; Gall, D; Gillanders, G H; Griffin, S; Grube, J; Gyuk, G; Hanna, D; Holder, J; Hughes, G; Humensky, T B; Kaaret, P; Kertzman, M; Khassen, Y; Kieda, D; Krawczynski, H; Krennrick, F; Lang, M J; Madhavan, A S; Maier, G; Majumdar, P; McArthur, S; McCann, A; Moriarty, P; Mukherjee, R; Nelson, T; de Bhroithe, A O'Faolain; Ong, R A; Orr, M; Otte, A N; Park, N; Perkins, J S; Pichel, A; Pohl, M; Popkow, A; Prokoph, H; Quinn, J; Ragan, K; Reyes, L C; Reynolds, P T; Roache, E; Saxon, D B; Schroedter, M; Sembroski, G H; Skole, C; Smith, A W; Staszak, D; Telezhinsky, I; Theiling, M; Tyler, J; Varlotta, A; Vassiliev, V V; Wakely, S P; Weekes, T C; Weinstein, A; Welsing, R; Williams, D A; Zitzer, B

    2013-01-01

    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 hours 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 adjustm...

  3. Very High Energy $\\gamma$-ray and Near Infrared observations of 1ES2344+514 during 2004-05

    CERN Document Server

    Godambe, S V; Baliyan, K S; Tickoo, A K; Thoudam, S; Dhar, V K; Chandra, P; Yadav, K K; Venugopal, K; Bhatt, N; Bhattacharya, S; Chanchalani, K; Ganesh, S; Goyal, H C; Joshi, U C; Kaul, R K; Kothari, M; Kotwal, S; Koul, M K; Koul, R; Sahaynathan, S; Shah, C; Sharma, M

    2007-01-01

    We have observed the BL Lac object 1ES2344+514 (z = 0.044) in Very High Energy (VHE) gamma-ray and near-infrared wavelength bands with TACTIC and MIRO telescopes respectively. The observations were made from 18th October to 9th December 2004 and 27th October 2005 to 1st January 2006. Detailed analysis of the TACTIC data indicates absence of a statistically significant gamma-ray signal both in overall data and on a nightly basis from the source direction. We estimate an upper limit of I($\\geq$1.5 TeV)$\\leq 3.84 \\times 10^{-12}$ photons cm$^{-2}$ s$^{-1}$ at a 3$\\sigma$ confidence level on the integrated $\\gamma$-ray flux. In addition, we have also compared TACTIC TeV light curves with those of the RXTE ASM (2-12keV) for the contemporary period and find that there are no statistically significant increases in the signal strengths from the source in both these energy regions. During 2004 IR observations, 1ES2344+514 shows low level (~0.06 magnitude) day-to-day variation in both, J & H bands. However, during ...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. Optically selected BL Lacertae candidates from the Sloan Digital Sky Survey Data Release Seven

    NARCIS (Netherlands)

    R.M. Plotkin; S.F. Anderson; W.N. Brandt; A.M. Diamond-Stanic; X. Fan; P.B. Hall; A.E. Kimball; M.W. Richmond; D.P. Schneider; O. Shemmer; W. Voges; D.G. York; N.A. Bahcall; S. Snedden; D. Bizyaev; H. Brewington; V. Malanushenko; E. Malanushenko; D. Oravetz; K. Pan; A. Simmons

    2010-01-01

    We present a sample of 723 optically selected BL Lac candidates from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) spectroscopic database encompassing 8250 deg(2) of sky; our sample constitutes one of the largest uniform BL Lac samples yet derived. Each BL Lac candidate has a high-quality S

  9. 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.

  10. 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...

  11. 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...

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

    Science.gov (United States)

    Aleksić, J.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Arcaro, C.; Babic, A.; 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.; 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.; Delgado Mendez, C.; Di Pierro, F.; Dominis Prester, D.; 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.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Godinović, N.; González Muñoz, A.; 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.; Nievas Rosillo, M.; 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.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Rodriguez Garcia, J.; Saito, T.; Saito, K.; Satalecka, K.; Scalzotto, V.; Scapin, V.; 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.

    2016-06-01

    Context. 1ES 1011+496 (z = 0.212) was discovered in very high-energy (VHE, E> 100 GeV) γ rays with MAGIC in 2007. The absence of simultaneous data at lower energies led to an incomplete characterization of the broadband spectral energy distribution (SED). Aims: 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. Methods: We analyzed data in the range from VHE to radio data from 2011 and 2012 collected by MAGIC, Fermi-LAT, Swift, KVA, OVRO, and Metsähovi in addition to optical polarimetry data and radio maps from the Liverpool Telescope and MOJAVE. Results: The VHE spectrum was fit with a simple power law with a photon index of 3.69 ± 0.22 and a flux above 150 GeV of (1.46 ± 0.16) × 10-11 ph cm-2 s-1. The source 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 measured in optical, while some bright features polarized up to 60% were observed in the radio jet. A similar trend in the rotation of the electric vector position angle was found in optical and radio. The radio maps indicated a superluminal motion of 1.8 ± 0.4 c, which is the highest speed statistically significant measured so far in a high-frequency-peaked BL Lac. Conclusions: For the first time, the high-energy bump in the broadband SED of 1ES 1011+496 could be fully characterized from 0.1 GeV to 1 TeV, which permitted a more reliable interpretation within the one-zone SSC scenario. The polarimetry data suggest that at least part of the optical emission has its origin in some of the bright radio features, while the low polarization in optical might be due to the contribution of parts of the radio jet with different orientations of the magnetic field with respect to the optical emission.

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

    OpenAIRE

    VERITAS Collaboration; Archambault, S.; Archer, A.; Barnacka, A.; Behera, B.; Beilicke, M.; Benbow, W.; Berger, K; Bird, R.; Boettcher, M.; J. H. Buckley(Department of Physics, Washington University, St. Louis, USA); Bugaev, V.; Cardenzana, J. V; M. Cerruti(Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645, USA); Chen, X.

    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...

  14. 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,...

  15. The disk-jet connection of Fermi 2LAC blazars

    Science.gov (United States)

    Du, L. M.; Xie, Zh. H.; Yi, T. F.; Xue, R.; Xu, Y. B.; Liu, W. G.; Wang, X. H.

    2016-07-01

    In this article, an estimator of the radiative power for blazars is proposed and is used in the study of the link between the accretion disk power and jet power. The results lend support to the disk-jet symbiosis. Since the blazars are strongly beamed sources, our results suggest that the Doppler enhancement of the sources needs to be removed to obtain physically reasonable results in the disk-jet connection study. The results after de-beaming suggest that FSRQs are accreting in the radiatively efficient regime, while the BL Lac population shows a flatter dependence between jet power and disk power, possibly due to a mixture of sources in the radiatively efficient (the broad lined BL Lacs) and inefficient (the bulk of the BL Lac population) regimes.

  16. Intranight optical variability of radio-quiet BL Lacertae objects

    CERN Document Server

    Liu, Yuan; Zhang, Shuang Nan

    2015-01-01

    Aims: The intranight variation (or microvariation) is a common phenomenon of radio-loud BL Lac objects. However, it is not clear whether the recently found radio-quiet BL Lac objects have the same properties. The occurrence rate of intranight variation is helpful in distinguishing the mechanism of the continuum of radio-quiet BL Lac objects. Methods: We conducted a photometric monitoring of 8 radio-quiet BL Lac objects by Xinglong 2.16m and Lijiang 2.4m telescopes. The differential light curves are calculated between each target and two comparison stars. To qualify the variation, the significance of variation is examined by scaled $F$-test. Results: No significant variation is found in the 11 sessions of light curves of 8 radio-quiet BL Lac objects (one galactic source is excluded). The lack of microvariation in radio-quiet BL Lac objects is consistent with the detection rate of microvariation in normal radio-quiet AGNs, but much lower than that of radio-loud AGNs. This result indicates that the continua of t...

  17. Is BZB J1450+5201 the most distant $\\gamma$-ray BL Lacertae object?

    OpenAIRE

    Liao, N. H.; Bai, J. M.; Wang, J. G.; Liu, H.T.; Zhang, J. J.; Jiang, Ning; Yuan, Z. L.; Chen, Liang

    2013-01-01

    BL Lacertae (BL Lac) objects at high redshifts ($z\\geq 2$) are rarely detected. Through careful analysis of the SDSS spectrum, BZB J1450+5201 is confirmed to be a high-$z$ BL Lac object with $z\\geq$ 2.471 by identifying the Ly$\\alpha$ 1216 and CIV 1548/1550 absorption lines. This indicates that BZB J1450+5201 is the most distant BL Lac object discovered to date. Careful analysis of the five-year \\fermi data of 2FGL J1451.0+5159 shows that its $\\gamma$-ray emission is robust with confidence le...

  18. 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

  19. Hadronic-Origin orphan TeV flare from the 1ES 1959+650

    CERN Document Server

    Sahu, Sarira; Sanabria, Juan Carlos

    2013-01-01

    The 1ES 1959+650 is a high-peaked BL Lacertae object. On 4th of June, 2002, it exhibited a strong TeV flare without any low energy counterpart, providing for the first time an example of an orphan flare from a blazar. Observation of this orphan flare is in striking disagreement with the predictions of the leptonic models thus challenging the conventional synchrotron self-Compton (SSC) interpretation of the TeV emission. Here we propose that, the low energy tail of the SSC photons in the blazar jet serve as the target for the Fermi-accelerated high energy protons of energy . 100 TeV, within the jet to produce the TeV photons through the decay of neutral pions from the delta resonance. Our model explains very nicely the observed TeV flux from this orphan flare and we also estimate the high energy neutrino flux from this flaring event.

  20. 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.

  1. 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.

  2. 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...

  3. 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.

  4. IDV Observations of BL0716+714 at 5 GHz

    Indian Academy of Sciences (India)

    H.-G Song; X. Liu; J. Liu; N. Marchili; T. P. Krichbaum

    2011-03-01

    A selected sample of intra-day variable AGN had been observed for 3–4 days per month at the Urumqi Observatory. The sample includes 7 target sources and 7 calibrators. The BL Lac object B0716+714 shows prominent intraday and long term variations.

  5. Discovery of a new BL Lacertae object /1E 1402.3 + 0416/ with the Einstein Observatory

    Science.gov (United States)

    Stocke, J.; Liebert, J.; Stockman, H.; Danziger, J.; Lub, J.; Maccacaro, T.; Griffiths, R.; Giommi, P.

    1982-01-01

    It is noted that only one BL Lac object, designated 1E 1402.3 + 0416, has so far been discovered as part of an optical identification program for a complete sample of faint X-ray sources detected with the Einstein Observatory. Consistent with previously X-ray-discovered BL Lacs, this object is blue and radio weak (17 mJy at 6 cm). It is pointed out that the percentage of BL Lacs in the faint extragalactic X-ray sample (2%) is smaller than the percentage at higher X-ray fluxes (6%). Over the same range in X-ray flux, the percentage of emission-line active galaxy nuclei (QSO + Seyferts) rises from 40% to 74%). This is seen as suggesting that BL Lacs do not evolve in a manner similar to quasars and are, therefore, not substantial contributors to the X-ray background.

  6. The Connection between X-ray- and Radio-Selected BL Lacertae Objects

    OpenAIRE

    Padovani, Paolo; Giommi, Paolo

    1994-01-01

    We explain the properties of X-ray selected BL Lacertae objects, under the assumption that they constitute the small minority of the BL Lac population with energy cutoff located in the UV/X-ray band, as suggested by their multifrequency spectra. In particular, we derive their X-ray luminosity function, log N-log S, and radio flux distribution starting from radio selected BL Lacs using a method that does not require any free parameters. Our hypothesis is at variance with the most common explan...

  7. The milliarcsecond polarization structure of six BL Lacertae objects

    International Nuclear Information System (INIS)

    Milliarcsecond resolution total intensity and linear polarization maps at GHz are presented for the BL Lacertae objects 0235 + 164, 0454 + 844, 1749 + 096, 1823 + 568, and 2200 + 420 (BL Lac). Maps of 1807 + 698 (3C 371), which has in the past been classified either as a BL Lacertae object or an N galaxy, are also presented. Appreciable polarization structure is found in 0454 + 844, 1823 + 568, and BL Lac; in each the polarization position angle in the knots lies within about 10 deg of the structural direction of the VLBI jet, suggesting that plane perpendicular shock waves may be common in these objects. The polarization of 3C 371 is weak, and is quite atypical of BL Lacertae objects. Superluminal motion in 1823 + 568 is suggested. Similar comparison for 0454 + 844 over four epochs confirms proper motion at mu about 0.14 mas/yr. Systematic differences in the VLBI polarization structures of BL Lacertae objects and quasars rule out the possibility that a significant fraction of BL Lacertae objects are gravitationally microlensed quasars. 87 refs

  8. Fifty years fused to lac.

    Science.gov (United States)

    Beckwith, Jonathan

    2013-01-01

    I recount the history of how I became interested in the use of gene fusions for studying biological problems. Initially, selections for mutations that would restore function to an inactivated lac operon unexpectedly yielded fusions in which lac was expressed from the controlling elements of upstream genes. Subsequently, by chance, I generated strains in which the lac operon was transposed from its normal position on the chromosome to a position close to the trp operon, thus facilitating sets of useful fusions of the two operons. The development of a more generalized technique for obtaining fusions by my student Malcolm Casadaban opened up a much broader set of biological problems that could be approached with fusions. Work on these problems included the study of protein translocation across membranes, the analysis of membrane protein topology, and the discovery of the pathway of electron transfer that leads to disulfide bond formation in proteins. PMID:24024632

  9. 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

  10. High-Level Expression of Bacillus naganoensis Pullulanase from Recombinant Escherichia coli with Auto-Induction: Effect of lac Operator

    Science.gov (United States)

    Xu, Yan; Chen, Wen Bo; Mu, Xiao Qing; Wang, Xinye; Xiao, Rong

    2013-01-01

    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 successful

  11. High-level expression of Bacillus naganoensis pullulanase from recombinant Escherichia coli with auto-induction: effect of lac operator.

    Science.gov (United States)

    Nie, Yao; Yan, Wei; Xu, Yan; Chen, Wen Bo; Mu, Xiao Qing; Wang, Xinye; Xiao, Rong

    2013-01-01

    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 successful

  12. The simultaneous low state spectral energy distribution of 1ES 2344+514 from radio to very high energies

    Science.gov (United States)

    Aleksić, J.; Antonelli, L. A.; Antoranz, P.; Asensio, M.; Backes, M.; Barres de Almeida, U.; Barrio, J. A.; Bednarek, W.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnefoy, S.; Bonnoli, G.; Borla Tridon, D.; Bretz, T.; Carmona, E.; Carosi, A.; Carreto Fidalgo, D.; 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.; Delgado Mendez, C.; 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.; Hadamek, A.; Hadasch, D.; Herrero, A.; Hose, J.; Hrupec, D.; Jankowski, F.; Kadenius, V.; Klepser, S.; Knoetig, M. L.; Krähenbühl, T.; Krause, J.; Kushida, J.; La Barbera, A.; Lelas, D.; Leonardo, E.; 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.; Nieto, D.; Nilsson, K.; Nowak, N.; Orito, R.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Partini, S.; Persic, M.; Pilia, M.; Prada, F.; Prada Moroni, P. G.; 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.; MAGIC Collaboration; Longo, F.; Lucarelli, F.; Pittori, C.; Vercellone, S.; AGILE Team; Bastieri, D.; Sbarra, C.; Fermi-LAT Collaboration; Angelakis, E.; Fuhrmann, L.; Nestoras, I.; Krichbaum, T. P.; Sievers, A.; Zensus, J. A.; F-GAMMA program; 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.

    2013-08-01

    Context. BL Lacertae objects are variable at all energy bands on time scales down to minutes. To construct and interpret their spectral energy distribution (SED), simultaneous broad-band observations are mandatory. Up to now, the number of objects studied during such campaigns is very limited and biased towards high flux states. Aims: We present the results of a dedicated multi-wavelength study of the high-frequency peaked BL Lacertae (HBL) object and known TeV emitter 1ES 2344+514 by means of a pre-organised campaign. Methods: The observations were conducted during simultaneous visibility windows of MAGIC and AGILE in late 2008. The measurements were complemented by Metsähovi, 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 synchrotron self-Compton model. Results: 1ES 2344+514 was found at very low flux states in both X-rays and very high energy gamma rays. Variability was detected in the low frequency radio and X-ray bands only, where for the latter a small flare was observed. The X-ray flare was possibly caused by shock acceleration characterised by similar cooling and acceleration time scales. MOJAVE VLBA monitoring reveals a static jet whose components are stable over time scales of eleven years, contrary to previous findings. There appears to be no significant correlation between the 15 GHz and R-band monitoring light curves. The observations presented here constitute the first multi-wavelength campaign on 1ES 2344+514 from radio to VHE energies and one of the few simultaneous SEDs during low activity states. The quasi-simultaneous Fermi-LAT data poses some challenges for SED modelling, but in general the SEDs are described well by both applied models. The resulting parameters are typical for TeV emitting HBLs

  13. 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.

  14. 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.

  15. 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.

  16. 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...

  17. 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.

  18. Transcriptional and functional analysis of galactooligosaccharide uptake by lacS in Lactobacillus acidophilus

    DEFF Research Database (Denmark)

    Andersen, Joakim Mark; Barrangou, Rodolphe; Abou Hachem, Maher;

    2011-01-01

    Probiotic microbes rely on their ability to survive in the gastrointestinal tract, adhere to mucosal surfaces, and metabolize available energy sources from dietary compounds, including prebiotics. Genome sequencing projects have proposed models for understanding prebiotic catabolism, but mechanisms...... and catabolism of GOS. Whole-genome oligonucleotide microarrays were used to survey the differential global transcriptome during logarithmic growth of L. acidophilus NCFM using GOS or glucose as a sole source of carbohydrate. Within the 16.6-kbp gal-lac gene cluster, lacS, a galactoside...... confirmation of the functional LacS permease not only for the utilization of lactose and GOS but also lactitol, suggesting a prominent role of LacS in the metabolism of a broad range of prebiotic β-galactosides, known to selectively modulate the beneficial gut microbiota....

  19. Search for Cross-Correlations of Ultra--High-Energy Cosmic Rays with BL Lacertae Objects

    CERN Document Server

    Abbasi, R U; Amman, J F; Archbold, G; Atkins, R; Bellido, J A; Belov, K; Belz, J W; Ben-Zvi, S Y; Bergman, D R; Burt, G W; Cao, Z; Clay, R W; Connolly, B C; Deng, W; Dawson, B R; Fedorova, Y; Findlay, J; Finley, C B; Hanlon, W F; Hoffman, C M; Hughes, G A; Holzscheiter, M H; Hüntemeyer, P; Jui, C C H; Kim, K; Kirn, M A; Loh, E C; Maestas, M M; Manago, N; Marek, L J; Martens, K; Matthews, J A J; Matthews, J N; O'Neill, A; Painter, C A; Perera, L P; Reil, K; Riehle, R; Roberts, M; Sasaki, M; Schnetzer, S R; Simpson, K M; Sinnis, G; Smith, J D; Snow, R; Sokolsky, P; Song, C; Springer, R W; Stokes, B T; Thomas, J R; Thomas, S B; Thomson, G B; Tupa, D; Westerhoff, S; Wiencke, L R; Zech, A

    2005-01-01

    Data taken in stereo mode by the High Resolution Fly's Eye (HiRes) air fluorescence experiment are analyzed to search for correlations between the arrival directions of ultra--high-energy cosmic rays with the positions of BL Lacertae objects. Several previous claims of significant correlations between BL Lacs and cosmic rays observed by other experiments are tested. These claims are not supported by the HiRes data. However, we verify a recent analysis of correlations between HiRes events and a subset of confirmed BL Lacs from the 10th Veron Catalog, and we study this correlation in detail. Due to the a posteriori nature of the search, the significance level cannot be reliably estimated and the correlation must be tested independently before any claim can be made. We identify the precise hypotheses that will be tested with statistically independent data.

  20. The WEBT BL Lacertae Campaign 2001 and its extension

    CERN Document Server

    Villata, M; Kurtanidze, O M; Nikolashvili, M G; Ibrahimov, M A; Papadakis, I E; Tosti, G; Hroch, F; Takalo, L O; Sillanpää, A; Hagen-Thorn, V A; Larionov, V M; Schwartz, R D; Basler, J; Brown, L F; Balonek, T J; Benítez, E; Ramírez, A; Sadun, A C; Boltwood, P; Carini, M T; Barnaby, D; Coloma, J M; Ros, J A; Dai, B Z; Xie, G Z; Mattox, J R; Rodríguez, D; Asfandiyarov, I M; Atkerson, A; Beem, J L; Bloom, S D; Chanturiya, S M; Ciprini, S; Crapanzano, S; De Diego, J A; Efimova, N V; Gardiol, D; Guerra, J C; Kahharov, B B; Kapanadze, B Z; Karttunen, H; Kato, T; Kimeridze, G N; Kudryavtseva, N A; Lainela, M; Lanteri, L; Larionova, E G; Maesano, M; Marchili, N; Massone, G; Monroe, T; Montagni, F; Nesci, R; Nilsson, K; Noble, J C; Nucciarelli, G; Ostorero, L; Papamastorakis, J; Pasanen, M; Peters, C S; Pursimo, T; Reig, P; Ryle, W; Sclavi, S; Sigua, L A; Uemura, M; Wills, W

    2004-01-01

    BL Lacertae has been the target of four observing campaigns by the Whole Earth Blazar Telescope (WEBT) collaboration. In this paper we present $UBVRI$ light curves obtained by the WEBT from 1994 to 2002, including the last, extended BL Lac 2001 campaign. A total of about 7500 optical observations performed by 31 telescopes from Japan to Mexico have been collected, to be added to the $\\sim 15600$ observations of the BL Lac Campaign 2000. All these data allow one to follow the source optical emission behaviour with unprecedented detail. The analysis of the colour indices reveals that the flux variability can be interpreted in terms of two components: longer-term variations occurring on a few-day time scale appear as mildly-chromatic events, while a strong bluer-when-brighter chromatism characterizes very fast (intraday) flares. By decoupling the two components, we quantify the degree of chromatism inferring that longer-term flux changes imply moving along a $\\sim 0.1$ bluer-when-brighter slope in the $B-R$ vers...

  1. Curvature of the spectral energy distribution, the dominant process for inverse Compton component and other jet properties in Fermi 2LAC blazars

    CERN Document Server

    Xue, R; Du, L M; Wang, Z R; Xie, Z H; Yi, T F; Xiong, D R; Xu, Y B; Liu, W G; Yu, X L

    2016-01-01

    We fit the spectral energy distributions (SEDs) of members of a large sample of Fermi 2LAC blazars to synchrotron and inverse Compton (IC) models. Our main results are as follows. (i) As suggested by previous works, the correlation between peak frequency and curvature can be explained by statistical or stochastic particle acceleration mechanisms. For BL Lacs, we find a linear correlation between synchrotron peak frequency and its curvature. The slope of the correlation is consistent with the stochastic acceleration mechanisms and confirm previous studies. For FSRQs, we also find a linear correlation, but its slope cannot be explained by previous theoretical models. (ii) We find a significant correlation between IC luminosity and synchrotron luminosity. The slope of the correlation of FSRQs is consistent with the EC process. And the slope of the correlation of BL Lac is consistent with the SSC process. (iii) We find several significant correlations between IC curvature and several basic parameters of blazars (...

  2. 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...

  3. 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...

  4. 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.

  5. [Identification of different lac with infrared spectrum].

    Science.gov (United States)

    Dong, Qin; Qiu, Jian; He, Run-xi; Zhang, Jian-yun

    2004-05-01

    Fourier infrared spectrum was used to differentiate raw lac, bleached las and lac mixed with resin. The results indicate that the infrared spectra of raw lac and lac mixed with resin are similar, so the authors can differentiate them by the following items: (1) the position and the shape of absorbing peak between 3500 and 2500 cm(-1), (2) the difference of the vibration peak at 1700 cm(-1) for C=O, (3) characteristic peak between 1200 and 1400 cm(-1), (4) the number of peaks and the change in the position of peak. But with bleached and graft copolymerization lacs the properties have been changed by chemical processing. Graft copolymerization of lac is made from methyl-acrylic acid-methyl fat by using potassium permanganate as stimulant. Their main differences are: the change of vibration peak of 1700 cm(-1) for C=O, a sharp small peak at 1558 cm(-1), a peak with middle strength at 681 cm(-1), and spliting to two small peaks at 1151 cm(-1). The experiment shows that the method of infrared spectrum is more scientific and effective than traditional method. PMID:15769053

  6. Is BL Lacertae an "orphan" AGN? Multiband and spectroscopic constraints on the parent population

    CERN Document Server

    Capetti, Alessandro; Buttiglione, Sara; ),

    2010-01-01

    We have analysed optical spectra of BL Lacertae, the prototype of its class, to verify the presence and possible flux variations of its broad Ha line. We used the spectroscopic information also to investigate the question of its parent population. Four spectra were acquired at the TNG in 2007-2008, when the source was in a relatively faint state. In three cases we were able to measure the broad Ha and several narrow emission lines. A comparison with previous results suggests that the broad Ha has increased by ~50% in ten years, a change not unusual for Broad Lined AGN. We estimated a black hole mass for BL Lac of 4-6 10^8 solar masses from its relation with the bulge luminosity. The virial mass estimated from the spectroscopic data is instead 20-30 times smaller. We suggest that this discrepancy is due to the BL Lac BLR being underluminous. Finally, we addressed the problem of the BL Lac parent population, comparing its isotropic quantities with those of other AGN classes. From the point of view of the narrow...

  7. The classification of BL Lacertae objects the Ca H&K break

    CERN Document Server

    Landt, H; Giommi, P

    2002-01-01

    We investigate why BL Lacertae objects (BL Lacs) have values of the Ca H&K break (a stellar absorption feature) lower than low-power radio galaxies and if its use is justified to separate the two classes. For this purpose we relate this parameter to the radio and optical core emissions, as well as to the X-ray powers, for a sample of ~90 radio sources. We find that the Ca H&K break value decreases with increasing jet powers, and that it also anti-correlates with the radio core dominance parameter but not with extended radio emission. Based on this we conclude that the Ca H&K break value of BL Lacs and radio galaxies is a suitable indicator of orientation. From the luminosity ratios between objects with low and high Ca H&K break values we constrain the average Lorentz factors for BL Lacs and low-power radio galaxies in the radio and X-ray band to Gamma ~ 2 -- 4 and derive average viewing angles for the galaxies. Our values are in agreement with results from independent methods. We find that the...

  8. 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.

  9. 3BL hotel management

    OpenAIRE

    MALECHOVÁ, Vendula

    2013-01-01

    The work is dedicated to Corporate Social Responsibility (CSR) and its application in the hotel. Part of this work are interviews with representatives of hotels representing the CSR best practices and interviews with other selected subjects. Comparison of the information reflects the current status of implementation of CSR in hotel management in the Czech Republic. The output of work is created CSR matrix. According the principles of 3 BL management matrix visualizes the organization current ...

  10. 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

  11. A new highest historical X-ray State in 1ES 1959+650

    Science.gov (United States)

    Kapanadze, Bidzina; Dorner, Daniela; Kapanadze, Sergo

    2016-07-01

    The nearby HBL source 1ES 1959+650 (z=0.047) shows a prolonged strong X-ray flaring activity since 2016 May 6, observed by X-ray Telescope onboard the Swift satellite (Swift-XRT) mostly in the framework of our Target of Opportunity (ToO) requests of different urgencies (ToO Request Number: 8051, 8099, 8178, 8192, 8204, 8224, 8230, 8257, 8261).

  12. Discovery of a BL Lacertae object (EXO 055625 - 3838.6) in the error box of H0557 - 385

    International Nuclear Information System (INIS)

    X-ray and optical data are presented of a new BL Lacertae type object (EXO 055625 - 3838.6) which has been serendipitously discovered in an EXOSAT CMA image and is located within the error box of HO557-385 (4U0557 - 38, 3A0557 - 383), a hard X-ray source previously identified with a Seyfert 1 galaxy. Although the soft X-ray flux of the BL Lac is 10 times higher than that of the Seyfert and the EXOSAT data are fully consistent with the BL Lac being the only counterpart of HO557 - 385, a substantial contribution to the hard X-ray flux from the Seyfert galaxy cannot be excluded. (author)

  13. Rapid X-ray Variability of the BL Lacertae Object PKS 2155-304

    OpenAIRE

    Zhang, Y.H.; Celotti, A.; Treves, A.; Chiappetti, L.; Ghisellini, G.; L. Maraschi(INAF National Institute for Astrophysics, I-00136 Rome, Italy); Pian, E.; Tagliaferri, G.; Tavecchio, F.; C. M. Urry

    1999-01-01

    (Abridged) We present a detailed power density spectrum and cross-correlation analysis of the X-ray light curves of the BL Lac object PKS 2155-304, observed with BeppoSAX in 1997 and 1996, aimed at exploring the rapid variability properties and the inter-band cross correlations in the X-rays. We also perform the same analysis on the (archival) X-ray light curve obtained with ASCA in 1994.

  14. 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...

  15. BL Lacertae complex spectral variability and rapid synchrotron flare detected with BeppoSAX

    CERN Document Server

    Ravasio, M; Ghisellini, G; Giommi, P; Nesci, R; Massaro, E; Chiappetti, L; Celotti, A; Costamante, L; Maraschi, L; Tavecchio, F; Tosti, G; Treves, A; Wolter, A; Balonek, T; Carini, M; Kato, T; Kurtanidze, O M; Montagni, F; Nikolashvili, M M; Noble, J; Nucciarelli, G; Raiteri, C M; Sclavi, S; Uemura, M; Villata, M

    2002-01-01

    We report on two BeppoSAX observations of BL Lac (2200+420) performed respectively in June and December 1999, as part of a ToO program to monitor blazars in high states of activity. During both runs the source has been detected up to 100 keV, but it showed quite different spectra: in June it was concave with a very hard component above 5-6 keV (alpha_1 ~ 1.6; alpha_2 ~ 0.15); in December it was well fitted by a single power law (alpha ~ 0.6). During the first BeppoSAX observation BL Lac showed an astonishing variability episode: the 0.3 - 2 keV flux doubled in ~ 20 minutes, while the flux above 4 keV was almost constant. This frequency-dependent event is one of the shortest ever recordered for BL Lac objects and places lower limits on the dimension and the magnetic field of the emitting region and on the energy of the synchrotron radiating electrons. A similar but less extreme behaviour is detected also in optical light curves, that display non-simultaneous, smaller fluctuations of ~ 20% in 20 min. We fit the...

  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. 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

  18. 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

  19. 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

  20. Arcsecond-Scale Radio Jets of Ultra-High-Energy Synchrotron Peak BL Lacs (UHBLs)

    Indian Academy of Sciences (India)

    Zhongzu Wu; Shengxu Yang; Minfeng Gu

    2014-09-01

    We present the arcsecond-scale jet structure and related radio properties for a sample of 9 UHBLs selected from Nieppola et al. (2006) with log(peak/Hz) > 20. Our preliminary results show that most of the UHBLs have compact structures, and their core dominance parameters are much larger than FR-I radio galaxies, suggesting that beaming may be prevalent in the jets of these sources.

  1. 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.

  2. Baryon Loading Efficiency and Particle Acceleration Efficiency of Relativistic Jets: Cases For Low Luminosity BL Lacs

    CERN Document Server

    Inoue, Yoshiyuki

    2016-01-01

    Relativistic jets launched by SMBHs are the most energetic particle accelerators in the universe. However, the baryon mass loading efficiency onto the jets from the accretion and the particle acceleration efficiency in the jets have been veiled in mystery. With the latest data sets, we perform multi-wavelength spectral analysis of quiescent spectra of 13 TeV gamma-ray detected HBLs following one-zone synchrotron-self-Compton (SSC) model. We determine the minimum, cooling break, and maximum electron Lorentz factors following the diffusive shock acceleration (DSA) theory. We find that HBLs have $P_B/P_e\\sim0.025$ where $P_B$ and $P_e$ is the Poynting and electron power, respectively. The radiative efficiency of the jets is found to be $P_{\\rm rad}/P_{\\rm jet}\\sim0.026$. $P_{\\rm rad}$ and $P_{\\rm jet}$ is the radiative and total jet power, respectively. We find that the jet power relates to the black hole mass as $P_{\\rm jet}/L_{\\rm Edd}\\sim0.036$. We further find that HBLs have the mass loading efficiency of $\\...

  3. 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...

  4. 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.

  5. -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.

  6. An HST/COS observation of broad Lyα emission and associated absorption lines of the BL Lacertae object H 2356-309

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Taotao [Department of Astronomy and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, Fujian 361005 (China); Danforth, Charles W.; Stocke, John T.; Shull, J. Michael [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Buote, David A. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697 (United States); Canizares, Claude R. [Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Gastaldello, Fabio, E-mail: fangt@xmu.edu.cn [IASF-Milano, INAF, via Bassini 15, Milan I-20133 (Italy)

    2014-11-01

    Weak spectral features in BL Lacertae objects (BL Lacs) often provide a unique opportunity to probe the inner region of this rare type of active galactic nucleus. We present a Hubble Space Telescope/Cosmic Origins Spectrograph observation of the BL Lac H 2356-309. A weak Lyα emission line was detected. This is the fourth detection of a weak Lyα emission feature in the ultraviolet (UV) band in the so-called high-energy peaked BL Lacs, after Stocke et al. Assuming the line-emitting gas is located in the broad line region (BLR) and the ionizing source is the off-axis jet emission, we constrain the Lorentz factor (Γ) of the relativistic jet to be ≥8.1 with a maximum viewing angle of 3.°6. The derived Γ is somewhat larger than previous measurements of Γ ≈ 3-5, implying a covering factor of ∼3% of the line-emitting gas. Alternatively, the BLR clouds could be optically thin, in which case we constrain the BLR warm gas to be ∼10{sup –5} M {sub ☉}. We also detected two H I and one O VI absorption lines that are within |Δv| < 150 km s{sup –1} of the BL Lac object. The O VI and one of the H I absorbers likely coexist due to their nearly identical velocities. We discuss several ionization models and find a photoionization model where the ionizing photon source is the BL Lac object that can fit the observed ion column densities with reasonable physical parameters. This absorber can either be located in the interstellar medium of the host galaxy or in the BLR.

  7. 1ES 0033+595 found in a very high state by INTEGRAL

    DEFF Research Database (Denmark)

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

    2014-01-01

    ; 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......Crab (10^-10 erg/cm2/s) in the 18-40 keV band (13 sec, about 7 sigma) while a 3 sigma upper limit of 11 mCrab (10^-10 erg/cm2/s) is provided in the 40-100 keV band. Using data collected from the ASDC SED Builder tool (http://tools.asdc.asi.it/SED/) we notice that this is the highest X-ray flux so far...

  8. 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.

  9. 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 ...

  10. Features of a knowledge based system REPSA1ES for probabilistic safety analysis

    International Nuclear Information System (INIS)

    This paper addresses the description of features of a knowledge based system REPSA1ES (Reliability Evaluation and Probabilistic Safety Analysis - level 1 - Expert System). The prototype software system has been designed for facilitating the probabilistic safety analysis (PSA) of complex hazardous industrial systems and to support the safety oriented decision making, during the design phase and operation of process systems. Taking into account known difficulties to manage complexity of logical and probabilistic modelling of nuclear power plants using the conventional PSA software packages we decided to represent information in a graphical form, whenever it is justified, and to automate the process of coding of objects to avoid errors. The software system consists of CAD modules, data bases, a shell for building expert systems and several other modules to enable: the effective communication with the user, data and knowledge acquisition, the initiation of inferring to support logical modelling of safety oriented systems, selection of reliability models with input parameters as well as the quantitative probabilistic evaluation of accident sequences. Due to the fact that the modelling and assessment process in PSA including the human reliability analysis (HRA) is complex and iterative, and can be automated only in some of its parts, it was assumed that the user can build the logic models himself or modify, in permissible cases, the event and fault trees created by relevant modules of the expert system. (author). 46 refs, 9 figs

  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. Multiwavelength Observations of the VHE Blazar 1ES 2344+514

    CERN Document Server

    Acciari, V A; Arlen, T; Aune, T; Beilicke, M; Benbow, W; Boltuch, D; Bugaev, V; Cannon, A; Ciupik, L; Cogan, P; Colin, P; Dickherber, R; Falcone, A; Fegan, S J; Finley, J P; Fortin, P; Fortson, L F; Furniss, A; Gall, D; Gillanders, G H; Grube, J; Guenette, R; Gyuk, G; Hanna, D; Holder, J; Horan, D; Hui, C M; Humensky, T B; Imran, A; Kaaret, P; Karlsson, N; Kertzman, M; Kieda, D; Kildea, J; Konopelko, A; Krawczynski, H; Krennrich, F; Lang, M J; LeBohec, S; Maier, G; Moriarty, P; Mukherjee, R; Ong, R A; Otte, A N; Pandel, D; Perkins, J S; Pichel, A; Pohl, M; Quinn, J; Ragan, K; Reynolds, P T; Rose, H J; Schroedter, M; Sembroski, G H; Smith, A W; Steele, D; Swordy, S P; Theiling, M; Toner, J A; Varlotta, A; Vassiliev, V V; Vincent, S; Wagner, R; Wakely, S P; Ward, J E; Weekes, T C; Weinstein, A; Weisgarber, T; Williams, D A; Wissel, S; Wood, M; Zitzer, B

    2011-01-01

    Multiwavelength observations of the high-frequency-peaked blazar 1ES2344+514 were performed from 2007 October to 2008 January. The campaign represents the first contemporaneous data on the object at very high energy (VHE, E >100 GeV) {\\gamma}-ray, X-ray, and UV energies. Observations with VERITAS in VHE {\\gamma}-rays yield a strong detection of 20 {\\sigma} with 633 excess events in a total exposure of 18.1 hours live-time. A strong VHE {\\gamma}-ray flare on 2007 December 7 is measured at F(>300 GeV) = (6.76 \\pm 0.62) \\times 10-11 ph cm-2 s-1, corresponding to 48% of the Crab Nebula flux. Excluding this flaring episode, nightly variability at lower fluxes is observed with a time-averaged mean of F(>300 GeV) = (1.06 \\pm 0.09) \\times 10-11 ph cm-2 s-1 (7.6% of the Crab Nebula flux). The differential photon spectrum between 390 GeV and 8.3 TeV for the time-averaged observations excluding 2007 December 7 is well described by a power law with a photon index of {\\Gamma} = 2.78 \\pm 0.09stat \\pm 0.15syst. Over the ful...

  13. 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

  14. Blått vann

    OpenAIRE

    Jensen, Poul Johannes

    2013-01-01

    Verket består av to "blå vann" i høybrent porselæn som er plassert i en sansehage. Et rundt "vann" med diameter 350 cm og retangulært "vann" på 125 x 700 cm. Begge "vann" er belyst med ledlys som kan skifte fargetemperatur/farge. Her er brukt blå porselensfliser for å gi en følelse av vann. Flisene som er ca. 23 x 23 cm er etter 1. brenning dekorert med vannløselige keramiske farger som tildels glir i hverandre og veksler i farge og nyanse, fra blått til grønt ettersom hvilke farge som ...

  15. Gamma-Ray and Multiwaveband Emission from Gamma-Ray-Loud BL Lacertae Objects

    Institute of Scientific and Technical Information of China (English)

    张雄; 赵刚; 郑广生; 张力

    2003-01-01

    We have collected 18 γ-ray-loud BL Lac with observed data in multiwavedand, we find that γ-ray flux densities correlate better with the near-IR flux densities than those with the optical or x-ray flux densities. There is no correlation between γ-ray and radio flux densities. Possible constraints on the γ-ray emission mechanism are discussed. We suggest that the main γ-ray radiation mechanism is probably the synchrotron self-Compton process. The inverse Compton scattering of the radiation from hot circumscribe dust, by beamed ultrarelativistic electrons, is likely to be an important complementary mechanism.

  16. BROAD Lyα EMISSION FROM THREE NEARBY BL LACERTAE OBJECTS

    International Nuclear Information System (INIS)

    We present far-UV HST/COS spectra of four nearby BL Lac objects. BL Lac spectra are dominated by a smooth, power-law continuum which arises in a relativistic jet. However, the spectra are not necessarily featureless; weak, broad- and/or narrow-line emission is sometimes seen in high-quality optical spectra. We present detections of Lyα emission in HST/COS spectra of Mrk 421 (z = 0.030) and PKS 2005-489 (z = 0.071) as well as an archival HST/GHRS observation of Mrk 501 (z = 0.0337). Archival HST/STIS observations of PKS 2155-304 (z = 0.116) show no Lyα emission to a very low upper limit. Using the assumption that the broad-line region (BLR) clouds are symmetrically placed around the active galactic nucleus (AGN), we use these measured Lyα emission features to constrain either the relativistic Γ values for the ionizing continuum produced by the jet (in the ionization-bounded case) or the mass of warm gas (in the density-bounded case). While realistic Γ values can be obtained for all four cases, the values for Mrk 421 and PKS 2155-304 are high enough to suggest that covering factors of BLR clouds of ∼1%-2% might be required to provide consistency with earlier values of Doppler boosting and viewing angles suggested for this class of BL Lacs. This discrepancy also exists in the case of M 87, where the amount of Doppler boosting in our direction is expected to be minimal, again suggestive of a small covering factor of BLR clouds. If, as these small covering factors might suggest, the assumptions of a density-bounded model could be more correct, then the observed Lyα luminosities require that BL Lac/FR 1 nuclei possess very little warm gas (10-4 to 10-5 Msun) as suggested by Guilbert et al. If these clouds are in pressure balance with a hotter (∼106 K) gas, the BLR contains too little mass to power the AGN by accretion alone.

  17. 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.

  18. BL Lacertae objects and radio-loud quasars within an evolutionary unified scheme

    Energy Technology Data Exchange (ETDEWEB)

    Vagnetti, F.; Cavaliere, A.; Giallongo, E. (Roma II Universita, Rome (Italy) Roma Osservatorio Astronomico, Rome (Italy))

    1991-02-01

    On the basis of a joint radio-optical analysis, different amounts of cosmological luminosity evolution in the optical band for flat- and steep-spectrum radio-loud quasars are found. Specifically, a slower evolution for the flat-spectrum quasars, evidence of a sluggish beamed component in the optical band additional to the canonical isotropic continuum is shown. The persistence of the beamed component in terms of a spectral evolution with the Doppler factor increasing somewhat in cosmic time is interpreted. The BL Lacertae objects are placed into this framework and an evolutionary unified scheme is proposed maintaining spectral and statistical continuity of BL Lacs with flat-spectrum quasars. Supportive observational evidence, and clues for the parent population, are discussed. 57 refs.

  19. Analyses of the Light Variations of OJ 287, 0716+714 and BL Lacertae

    Science.gov (United States)

    Wang, Hong-tao; Pan, Yan-ping

    2013-01-01

    OJ 287 is a BL Lac object which exhibits intense activities of low peak-frequencies. Its energy spectrum in low frequency band is quite similar with those of two other TeV BL Lac objects (i.e., 0716+714 and BL Lacertae). However, the Cerenkov telescope did not detect its TeV rays. By using the observational data of these three heavenly bodies and comparing the discrepan- cies of their minimal periods of light variations and delays at 22 GHz, 37 GHz and B-waveband, we have further investigated the possible reason why the TeV gamma-rays of OJ 287 have not been observed. The results of analyses are as fol- lows. (1) For the minimal periods of light variations, the periods of OJ 287 at 37 GHZ and B-waveband are short. At 22 GHz the results of OJ 287 and 0716+714 are comparable, but the period of OJ 287 is much shorter in comparison with that of BL Lacertae, and this shows that its activity is more intense. However, the TeV gamma-rays of OJ 287 have not been detected, which implies that the radiation of OJ 287 in TeV waveband may have no connection with the minimal periods of light variations in these three low-energy wavebands. (2) In respect of delays, the delay of OJ 287 in the B waveband with respect to 37 GHz is longer than that of 0716+714, but shorter than that of BL Lacertae. Its delay at 37 GHz in respect to 22 GHz is shorter than that of 0716+714. Meanwhile, the delay of BL Lacertae at 37 GHz in respect to 22 GHz is negative, which implies that 22 GHz precedes 37 GHz. Via the comparison and analysis of delays, no obvious differences between OJ 287 and 0716+714 as well as BL Lacertae have been found. On the side of energy spectra, it is quite possible that due to the steep energy spectrum of OJ 287 in TeV waveband, the Cerenkov telescope has not detected the gamma radiation of OJ 287. However, nowadays it is still not clear whether the steep energy spectrum in TeV energy range has some influence on the light variations in low energy realm.

  20. [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...

  1. 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...

  2. 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...

  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. 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...

  5. Des Lacs National Wildlife Refuge Water Management Plan 1966

    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...

  6. 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...

  7. Des Lacs National Wildlife Refuge Water Management Plan 1958

    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...

  8. Des Lacs National Wildlife Refuge Water Management Plan 1968

    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...

  9. Des Lacs National Wildlife Refuge Water Management Plan 2013

    Data.gov (United States)

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

  10. Des Lacs National Wildlife Refuge Water Management Plan 1993

    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...

  11. Des Lacs National Wildlife Refuge Water Management Plan 1965

    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 1957

    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 1964

    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 1970

    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. Des Lacs National Wildlife Refuge Water Management Plan 1962

    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...

  16. Des Lacs National Wildlife Refuge Water Management Plan 2008

    Data.gov (United States)

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

  17. 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...

  18. Des Lacs National Wildlife Refuge Water Management Plan 2014

    Data.gov (United States)

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

  19. Des Lacs National Wildlife Refuge Water Management Plan 2012

    Data.gov (United States)

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

  20. Des Lacs National Wildlife Refuge Water Management Plan 1967

    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...

  1. Des Lacs National Wildlife Refuge Water Management Plan 1963

    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...

  2. Des Lacs National Wildlife Refuge Water Management Plan 1956

    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...

  3. Des Lacs National Wildlife Refuge Water Management Plan 2010

    Data.gov (United States)

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

  4. Des Lacs National Wildlife Refuge Water Management Plan 1960

    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...

  5. Des Lacs National Wildlife Refuge Water Management Plan 2009

    Data.gov (United States)

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

  6. Des Lacs National Wildlife Refuge Water Management Plan 2011

    Data.gov (United States)

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

  7. Des Lacs National Wildlife Refuge Water Management Plan 2007

    Data.gov (United States)

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

  8. Monthly narrative reports for the Des Lacs Wildlife Refuge, 1937

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs and Lostwood Migratory Waterfowl Refuges outlines Refuge accomplishments from January through April of 1937. The report begins by...

  9. 76 FR 68124 - Television Broadcasting Services; Fond du Lac, WI

    Science.gov (United States)

    2011-11-03

    ... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 73 Television Broadcasting Services; Fond du Lac, WI AGENCY: Federal Communications Commission. ACTION: Proposed rule. SUMMARY: In this document, the Commission denies a petition...

  10. 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...

  11. Des Lacs National Wildlife Refuge Water Management Plan 1996

    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 1998

    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. This plan contains...

  13. Des Lacs National Wildlife Refuge Water Management Plan 1999

    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. This plan contains...

  14. Des Lacs National Wildlife Refuge Water Management Plan 2006

    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. This plan contains 2005...

  15. Des Lacs National Wildlife Refuge Water Management Plan 1997

    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. This plan contains...

  16. Des Lacs National Wildlife Refuge Water Management Plan 2002

    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. This plan contains 2001...

  17. Des Lacs National Wildlife Refuge Water Management Plan 2016

    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. This plan contains 2015...

  18. 1951 gill net studies : Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Report on the gill net studies conducted on Des Lacs National Wildlife Refuge lakes. The net studies indicated that severe, if not complete, winter kill was...

  19. 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...

  20. 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...

  1. 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.

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

    DEFF Research Database (Denmark)

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

    1993-01-01

    , 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...... experimentally by constructing E. coli strains, in which the chromosomal atp operon is transcribed from the lacUV5 and the tacI promoter. We measured the concentration of the c subunit of H+-ATPase, and found that the expression of this enzyme could be modulated between non-detectable levels and up to five times...... the wild-type level. Thus, in the absence of inducer, no expression of atp genes could be detected when the atp operon was controlled by the lacUV5 promoter, and we estimate that the expression was less than 0.0025 times the wild-type level. We show that the introduction of a lac Y mutation facilitated...

  3. Den Blå Drage

    DEFF Research Database (Denmark)

    Ingerslev, Gitte Holten

    Denne publikation i serien Læselyst tjener tre formål. Den evaluerer læseprojektet Den blå drage i efteråret 2004 på Byskolen i Svendborg ? et projekt ledet af forfatteren Josefine Ottesen. Desuden gøres der rede for nogle af de teorier der støtter og begrunder arbejdsmåde og resultater i projektet...

  4. The HST Survey of BL Lacertae Objects: Morphological Properties of Low redshift Host Galaxies

    CERN Document Server

    Falomo, R; Treves, A; Urry, C M; 10.1086/317044

    2009-01-01

    We report on the optical properties of a sample of 30 BL Lac host galaxies in the redshift range $0.03BL Lac nucleus is well centered in the main body of its host galaxy, a result that argues strongly against the microlensing hypothesis for any significant fraction of the population. A search for faint sub-structures in the host galaxies has not revealed notable signatures of tidal distortions or sub-components (faint disks, bars, X features, etc.), and with only one exception, there are no prominent dusty features in the central regions. Instead, the B...

  5. Studies of the Jet in BL Lacertae I. Recollimation Shock and Moving Emission Features

    CERN Document Server

    Cohen, M H; Arshakian, T G; Homan, D C; Hovatta, T; Kovalev, Y Y; Lister, M L; Pushkarev, A B; Richards, J L; Savolainen, T

    2014-01-01

    Parsec-scale VLBA images of BL Lac at 15 GHz show that the jet contains a permanent quasi-stationary emission feature 0.26 mas (0.34 pc projected) from the core, along with numerous moving features. In projection, the tracks of the moving features cluster around an axis at position angle -166.6 deg that connects the core with the standing feature. The moving features appear to emanate from the standing feature in a manner strikingly similar to the results of numerical 2-D relativistic magneto-hydrodynamic (RMHD) simulations in which moving shocks are generated at a recollimation shock. Because of this, and the close analogy to the jet feature HST-1 in M87, we identify the standing feature in BL Lac as a recollimation shock. We assume that the magnetic field dominates the dynamics in the jet, and that the field is predominantly toroidal. From this we suggest that the moving features are compressions established by slow and fast mode magneto-acoustic MHD waves. We illustrate the situation with a simple model in...

  6. Very high-resolution observations of the radio sources NRAO 150, OJ 287, 3C 273, M87, 1633+38, BL Lacertae, and 3C 454. 3

    Energy Technology Data Exchange (ETDEWEB)

    Kellermann, K.I. (National Radio Astronomy Observatory, Green Bank, WV); Shaffer, D.B.; Purcell, G.H.

    1977-02-01

    Very long baseline interferometer observations made at a wavelength of 2 and 2.8 cm with baselines ranging from 54 to 291 million wavelengths show a number of radio sources with only slightly resolved components, even on the longest baselines; the quasars 1633 + 38 and 3C 454.3, the objects OJ 287 and BL Lac, and the nucleus of M87 (Virgo A, 3C 274) all contain components < or approximately 0.4 milli-arcsec. The smallest component observed is in the core of 3C 454.3, which contains about 50% of the total flux density and is < or approximately 0.2 milli-arcsec in diameter. The compact component in the nucleus of M87 is < or approximately 1.5 light-months across, and contains about one-third of the total flux density of the nucleus at 2.8 cm. NRAO 150 and BL Lac are double: the components of NRAO 150 are separated by 0.6 milli-arcsec, while BL Lac has an elongated structure consisting of a large (1.4 milli-arcsec) component separated by 1.25 milli-arcsec from a smaller (0.5 milli-arcsec) variable one. The present data on 3C 273 are consistent with triple models similar to those discussed previously, but with a somewhat greater apparent separation of components.

  7. 两类BL Lac天体和FSRQs之间的关系∗%The Relation among the Two Types of BL Lac Obj ects and FSRQs

    Institute of Scientific and Technical Information of China (English)

    徐云冰; 易庭丰

    2014-01-01

    收集了109个 blazar天体(HBLs 51个,LBLs 40个,FSRQs 18个)的相关观测数据,对该样本的黑洞质量、吸积率、热光度和红移的分布规律进行了统计分析,讨论了吸积率与热光度、黑洞质量与热光度之间的关系,结果发现:(1)存在一个从 FSRQs经 LBLs到 HBLs 的演化序列;(2)爱丁顿吸积率是影响 blazar天体三个子类之间演化序列的主要因素;(3)blazar 天体三个子类的热光度需要进行多普勒效应改正。%In this paper,we collected 109 samples of blazar(51 HBLs,40 LBLs,18 FSRQs),then ana-lyzed the statistical distributions of black hole mass,accretion rate,bolometric luminosity and red-shifts of the samples,and discussed the relationship between the black hole mass and the bolo-metric luminosity,and between the accretion rate and the bolometric luminosity.At last,we drew the following conclusions:(1 )There are an evolutionary sequence of properties from FSRQs through LBLs to HBLs;(2)The main reason for the evolutionary sequence of three subclass of blazar may be Edditon ratio rather than black hole mass;(3)The observed bolometric luminosity must be corrected for the Doppler effect.

  8. 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

  9. 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.

  10. 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...

  11. In vivo expression of the lacY gene in two segments leads to functional lac permease

    International Nuclear Information System (INIS)

    The lacY gene of Escherichia coli was cut into two approximately equal-size fragments with Afl II and subcloned individually or together under separate lac operator/promoters in plasmid pT7-5. Under these conditions, lac permease is expressed in two portions: (i) the N-terminal portion (the N terminus, the first six putative transmembrane helices, and most of putative loop 7) and (ii) the C-terminal portion (the last six putative transmembrane helices and the C terminus). Cells harboring pT7-5 encoding both fragments transport lactose at about 30% the rate of cells expressing intact permease to a comparable steady-state level of accumulation. In contrast, cells expressing either half of the permease independently do not transport lactose. As judged by [35S]methionine labeling and immunoblotting, intact permease in completely absent from the membrane of cells expressing lacY fragments either individually or together. Thus, transport activity must result from an association between independently synthesized pieces of lac permease. When the gene fragments are expressed individually, the N-terminal portion of the permease is observed inconsistently, and the C-terminal portion is not observed. When the gene fragments are expressed together, polypeptides identified as the N- and C-terminal moieties of the permease are found in the membrane. It is concluded that the N- or C-terminal halves of lac permease are proteolyzed when synthesized independently and that association between the two complementing polypeptides leads to a more stable, catalytically active complex

  12. Radio outburst of BL Lacertae

    Science.gov (United States)

    Buemi, C. S.; Leto, P.; Trigilio, C.; Umana, G.; Giroletti, M.; Orienti, M.; Raiteri, C. M.; Villata, M.; Bach, U.

    2013-04-01

    We report on extremely high radio flux of BL Lacertae at 43 and 8 GHz. Observations at 43 GHz with the 32 m radio telescope in Noto (Italy) revealed a flux density of 10.5 +/- 0.2 Jy on 2013 April 10.65, while observations at 8 GHz with the 32 m radio telescope in Medicina (Italy) detected a flux density of 8.2 +/- 0.7 Jy on April 12.22. These extremely high radio fluxes show that the radio activity likely correlated to the strong optical, near-infrared, and gamma-ray activity of 2011-2012 (see ATels #4028, #4031, #4155, #4271, #4277, #4349, #4565, #4600), and X-ray activity of late 2012 (ATels #4557, #4627), is far to be exhausted.

  13. Structural explanation for allolactose (lac operon inducer) synthesis by lacZ β-galactosidase and the evolutionary relationship between allolactose synthesis and the lac repressor.

    Science.gov (United States)

    Wheatley, Robert W; Lo, Summie; Jancewicz, Larisa J; Dugdale, Megan L; Huber, Reuben E

    2013-05-01

    β-Galactosidase (lacZ) has bifunctional activity. It hydrolyzes lactose to galactose and glucose and catalyzes the intramolecular isomerization of lactose to allolactose, the lac operon inducer. β-Galactosidase promotes the isomerization by means of an acceptor site that binds glucose after its cleavage from lactose and thus delays its exit from the site. However, because of its relatively low affinity for glucose, details of this site have remained elusive. We present structural data mapping the glucose site based on a substituted enzyme (G794A-β-galactosidase) that traps allolactose. Various lines of evidence indicate that the glucose of the trapped allolactose is in the acceptor position. The evidence includes structures with Bis-Tris (2,2-bis(hydroxymethyl)-2,2',2″-nitrilotriethanol) and L-ribose in the site and kinetic binding studies with substituted β-galactosidases. The site is composed of Asn-102, His-418, Lys-517, Ser-796, Glu-797, and Trp-999. Ser-796 and Glu-797 are part of a loop (residues 795-803) that closes over the active site. This loop appears essential for the bifunctional nature of the enzyme because it helps form the glucose binding site. In addition, because the loop is mobile, glucose binding is transient, allowing the release of some glucose. Bioinformatics studies showed that the residues important for interacting with glucose are only conserved in a subset of related enzymes. Thus, intramolecular isomerization is not a universal feature of β-galactosidases. Genomic analyses indicated that lac repressors were co-selected only within the conserved subset. This shows that the glucose binding site of β-galactosidase played an important role in lac operon evolution. PMID:23486479

  14. Parsec-scale jet precession in BL Lacertae (2200+420)

    CERN Document Server

    Caproni, Anderson; Monteiro, Hektor

    2012-01-01

    BL Lacertae is the prototype of the BL Lac class of active galactic nuclei, exhibiting intensive activity on parsec (pc) scales, such as intense core variability and multiple ejections of jet components. In particular, in previous works the existence of precession motions in the pc-scale jet of BL Lacertae has been suggested. In this work we revisit this issue, investigating temporal changes of the observed right ascension and declination offsets of the jet knots in terms of our relativistic jet-precession model. The seven free parameters of our precession model were optimized via a heuristic cross-entropy method, comparing the projected precession helix with the positions of the jet components on the plane of the sky and imposing constraints on their maximum and minimum superluminal velocities. Our optimized best model is compatible with a jet having a bulk velocity of 0.9824c, which is precessing with a period of about 12.1 yr in the observer's reference frame and changing its orientation in relation to the...

  15. 1ES 1113+432: Luminous, soft X-ray outburst from a nearby cataclysmic variable (AR Ursae Majoris)

    Science.gov (United States)

    Remillard, R. A.; Schachter, J. F.; Silber, A. D.; Slane, P.

    1994-01-01

    A remarkable X-ray transient from the Einstein Slew Survey, 1 ES 1113+432, is identified with a nearby, short-period cataclysmic variable. Wenzel (1993) has confirmed that the optical counterpart is the variable star, AR UMa (cataloged as 'semiregular'), erroneously reported 5.7 min southeast of the true position. One of the Einstein slew observations recorded a flux of 43 IPC counts/s, which is an order of magnitude above the flux observed from the brightest cataclysmic variables in other X-ray surveys. The outburst spectrum is extremely 'soft,' with an implied blackbody temperature of approximately 22 eV. The optical counterpart (V = 16.5) exhibits a strong UV component, TiO bands from an M star, and broadened Balmer emission lines. Optical states as bright as V approx. 13 were found on photographs from the Harvard Plate Library, confirming outburst behavior in the optical counterpart. The historical photographic record suggests that 1ES 1113+432 remains in a low-accretion state most of the time. Both of the soft X-ray spectrum and the transitions between high and low-accretion states are suggestive of the AM Her (magnetic) subclass. Photometric observations in the I band show 0.18 mag modulations at a period of 0.966 hr. These are interpreted as ellipsiodal variations in the secondary star for a binary period of 1.932 hr, which is near the lower boundary of the 'period gap' in the histogram, of orbital periods of accreting white dwarfs. Thus 1ES 1113+432 provides the rare opportunity to study a secondary star in a cataclysmic binary that has evolved through the period gap. The optical spectral features from the secondary imply a spectral type of approximately M6 and a distance of approximately 88 pc. The peak luminosity in the soft X-ray component (unabsorbed) is then estimated to be 3 X 10(exp 33) ergs/s, assuming emission from a blackbody slab with a temperature of 22 eV. While this luminosity is higher than previous measures of the soft X-ray component, it

  16. 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

  17. Blødningsforstyrrelser hos kvinder

    DEFF Research Database (Denmark)

    Astrup, Karen

    1994-01-01

    Efteruddannelsesartikel for praktiserende læger om undersøgelse og behandling af blødningsforstyrrelser hos kvinder i almen praksis. Udgivelsesdato: 1994......Efteruddannelsesartikel for praktiserende læger om undersøgelse og behandling af blødningsforstyrrelser hos kvinder i almen praksis. Udgivelsesdato: 1994...

  18. 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.

  19. 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

    2003-01-01

    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∼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 (IIALacS) almost identical to the IIA domain of S. thermophilus LacS. Experiments performed with purified proteins showed that S. salivarius IIALacS was reversibly phosphorylated on a histidine residue at position 552 not only by HPr(His∼P) but also by HPr(Ser-P)(His∼P), a doubly phosphorylated form of HPr present in large amounts in rapidly growing S. salivarius cells. Two other major S. salivarius PTS proteins, IIABLMan and IIABHMan, were unable to phosphorylate IIALacS. The effect of LacS phosphorylation on growth was studied with strain G71, an S. salivarius enzyme I-negative mutant that cannot synthesize HPr(His∼P) or HPr(Ser-P)(His∼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. PMID:14617640

  20. The Optical Microvariability and Spectral Changes of the BL Lacertae Object S5 0716+714

    Indian Academy of Sciences (India)

    H. Poon; J. H. Fan; J. N. Fu

    2011-03-01

    The BL Lac object S5 0716+714 was monitored in the optical band during October 2008, December 2008 and February 2009. We achieved a best temporal resolution of about 5 min in the bands. The source was active during the whole monitoring campaign. It showed microvariability in 13 days out of 14 days of observation. Four fast flares were observed with amplitudes ranging from 0.3–0.75 mag. The overall amplitude changes during the whole campaign are ∼ 0. 89, ∼ 0. 80, ∼ 0. 73, and ∼ 0. 51. On internight time scales, strong bluer-when-brighter chromatism was found while different spectral behaviours were found on intranight time scales.

  1. GENERALIZED FUZZY FILTERS OF BL-ALGEBRAS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The concept of quasi-coincidence of a fuzzy interval value with an interval valued fuzzy set is considered. In fact, this is a generalization of quasi-coincidence of a fuzzy point with a fuzzy set. By using this new idea, the notion of interval valued (∈, ∈∨q)-fuzzy filters in BL-algebras which is a generalization of fuzzy filters of BL-algebras, is defined, and related properties are investigated. In particular, the concept of a fuzzy subgroup with thresholds is extended to the concept of an interval valued fuzzy filter with thresholds in BL-algebras.

  2. Studies of the jet in BL Lacertae. I. Recollimation shock and moving emission features

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, M. H.; Hovatta, T. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Meier, D. L. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Arshakian, T. G. [I. Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln (Germany); Homan, D. C. [Department of Physics, Denison University, Granville, OH 43023 (United States); Kovalev, Y. Y. [Astro Space Center of Lebedev Physical Institute, Profsoyuznaya 84/32, 117997 Moscow (Russian Federation); Lister, M. L.; Richards, J. L. [Department of Physics and Astronomy, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907 (United States); Pushkarev, A. B.; Savolainen, T., E-mail: mhc@astro.caltech.edu [Max-Planck-Institut für Radioastronomie, Auf Dem Hügel 69, D-53121 Bonn (Germany)

    2014-06-01

    Parsec-scale VLBA images of BL Lac at 15 GHz show that the jet contains a permanent quasi-stationary emission feature 0.26 mas (0.34 pc projected) from the core, along with numerous moving features. In projection, the tracks of the moving features cluster around an axis at a position angle of –166.°6 that connects the core with the standing feature. The moving features appear to emanate from the standing feature in a manner strikingly similar to the results of numerical two-dimensional relativistic magneto-hydrodynamic (RMHD) simulations in which moving shocks are generated at a recollimation shock (RCS). Because of this, and the close analogy to the jet feature HST-1 in M87, we identify the standing feature in BL Lac as an RCS. We assume that the magnetic field dominates the dynamics in the jet, and that the field is predominantly toroidal. From this we suggest that the moving features are compressions established by slow and fast mode magneto-acoustic MHD waves. We illustrate the situation with a simple model in which the slowest moving feature is a slow-mode wave, and the fastest feature is a fast-mode wave. In the model, the beam has Lorentz factor Γ{sub beam}{sup gal}≈3.5 in the frame of the host galaxy and the fast mode wave has Lorentz factor Γ{sub Fwave}{sup beam}≈1.6 in the frame of the beam. This gives a maximum apparent speed for the moving features, β{sub app} = v{sub app}/c = 10. In this model the Lorentz factor of the pattern in the galaxy frame is approximately three times larger than that of the beam itself.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. Induction of the lac carrier and an associated membrane protein in Escherichia coli

    International Nuclear Information System (INIS)

    Induction of the lac operon in wild type Escherichia coli strains results in synthesis of a 16 kilodalton inner membrane protein in addition to the known products of the lacZ, lacY and lacA genes. Cells carrying the lacY gene on a plasmid over produce this 16 kilodalton polypeptide as well as the Lac carrier, the membrane protein product of the lacY gene. However, [35S]methionine labeling of minicells carrying the lacY plasmid shows that the 16 kDa protein is not synthesized from the plasmid DNA. The 16 kDa protein was purified and partially characterized. It is an acidic membrane protein of apparent molecular weight 15,800 whose amino terminal sequence (NH2-Met-Arg-Asn-Phe-Asp-Leu-) does not correspond to any nucleotide sequence known in lac operon DNA. Using antibody prepared to the purified 16 kDa protein, a quantitative analysis of conditions under which this protein is made was accomplished, and reveals that the amount of 16 kDa protein which appears in the membrane is proportional to lac operon expression. Hybridization of a synthetic oligonucleotide probe complementary to the 5' end of 16 kDa protein mRNA shows that its synthesis is regulated at the level of transcription. A description of attempts to clone this gene is given. Possible functional roles for the 16 kDa protein are discussed

  9. Very high-resolution observations of the radio sources NRAO 150, OJ 287, 3C 273, M87, 1633+38, BL Lacertae, and 3C 454.3

    International Nuclear Information System (INIS)

    Very long baseline interferometer observations made at a wavelength of 2 and 2.8 cm with baselines ranging from 54 to 291 million wavelengths show a number of radio sources with only slightly resolved components, even on the longest baselines; the quasars 1633 + 38 and 3C 454.3, the objects OJ 287 and BL Lac, and the nucleus of M87 (Virgo A, 3C 274) all contain components < or approximately 0.4 milli-arcsec. The smallest component observed is in the core of 3C 454.3, which contains about 50% of the total flux density and is < or approximately 0.2 milli-arcsec in diameter. The compact component in the nucleus of M87 is < or approximately 1.5 light-months across, and contains about one-third of the total flux density of the nucleus at 2.8 cm. NRAO 150 and BL Lac are double: the components of NRAO 150 are separated by 0.6 milli-arcsec, while BL Lac has an elongated structure consisting of a large (1.4 milli-arcsec) component separated by 1.25 milli-arcsec from a smaller (0.5 milli-arcsec) variable one. The present data on 3C 273 are consistent with triple models similar to those discussed previously, but with a somewhat greater apparent separation of components

  10. 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.

  11. Identification of gamma-ray emission from BZB J1450+5201: the most distant gamma-ray BL Lacertae object at z=2.47

    CERN Document Server

    Liao, N H; Liu, H T; Jiang, Ning; Yuan, Z L; Chen, Liang

    2013-01-01

    $\\gamma$-ray BL Lacertae objects (BL Lacs) with high redshifts ($z\\geq2$) are rarely detected. We report on an analysis of \\fermi data from five-year observation of 2FGL J1451.0+5159 whose $\\gamma$-ray emission is doubtful in the second \\fermi catalog (2FGL). It is detected at a higher energy, 3-10 GeV, with 6.7$\\sigma$ from our analysis than at 1-3 GeV from the 2FGL. The $\\gamma$-ray emission of the source is identified to be valid. Association presented in the 2FGL, between 2FGL J1451.0+5159 and BZB J1450+5201 whose redshift is suggested as 2.47, has been confirmed. BZB J1450+5201 appears to be the most distant $\\gamma$-ray BL Lac discovered to date. Multi-wavelength data from radio to $\\gamma$-ray energies are analyzed, indicating that this intermediate synchrotron peaked (ISP) source seems to be no difference from other ISP sources at lower redshifts in the second LAT AGN catalog. The pure SSC model is likely ruled out due to the extreme value of Doppler factor. Scattering of weak external emission plus S...

  12. 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.

  13. Simultaneous Multiwavelength Observations of the Blazar 1ES 1959+650 at a Low TeV Flux

    International Nuclear Information System (INIS)

    We present the results from a multiwavelength campaign on the TeV blazar 1ES 1959+650, performed in 2006 May. 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, the MAGIC telescope, and other ground-based facilities. The source spectral energy distribution (SED), derived from Suzaku and MAGIC observations at the end of 2006 May, 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 synchrotron peak is located in the X-ray band and moves to higher energies as the source gets brighter, with the X-ray fluxes above it varying more rapidly than the X-ray fluxes at lower energies. The variability behavior observed in the X-ray band cannot be produced by emitting regions varying independently and suggests instead some sort of 'standing shock' scenario. The overall SED is well represented by a homogeneous one-zone synchrotron inverse Compton emission model, from which we derive physical parameters that are typical of high-energy peaked blazars.

  14. THE FIRST FERMI MULTIFREQUENCY CAMPAIGN ON BL LACERTAE: CHARACTERIZING THE LOW-ACTIVITY STATE OF THE EPONYMOUS BLAZAR

    International Nuclear Information System (INIS)

    We report on observations of BL Lacertae during the first 18 months of Fermi LAT science operations and present results from a 48 day multifrequency coordinated campaign from 2008 August 19 to 2008 October 7. The radio to gamma-ray behavior of BL Lac is unveiled during a low-activity state thanks to the coordinated observations of radio-band (Metsaehovi and VLBA), near-IR/optical (Tuorla, Steward, OAGH, and MDM), and X-ray (RXTE and Swift) observatories. No variability was resolved in gamma rays during the campaign, and the brightness level was 15 times lower than the level of the 1997 EGRET outburst. Moderate and uncorrelated variability has been detected in UV and X-rays. The X-ray spectrum is found to be concave, indicating the transition region between the low- and high-energy components of the spectral energy distribution (SED). VLBA observation detected a synchrotron spectrum self-absorption turnover in the innermost part of the radio jet appearing to be elongated and inhomogeneous, and constrained the average magnetic field there to be less than 3 G. Over the following months, BL Lac appeared variable in gamma rays, showing flares (in 2009 April and 2010 January). There is no evidence for the correlation of gamma rays with the optical flux monitored from the ground in 18 months. The SED may be described by a single-zone or a two-zone synchrotron self-Compton (SSC) model, but a hybrid SSC plus external radiation Compton model seems to be preferred based on the observed variability and the fact that it provides a fit closest to equipartition.

  15. 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.

  16. Chaos in hydrodynamic BL Herculis models

    CERN Document Server

    Smolec, R

    2014-01-01

    We present non-linear, convective, BL Her-type hydrodynamic models that show complex variability characteristic for deterministic chaos. The bifurcation diagram reveals a rich structure, with many phenomena detected for the first time in hydrodynamic models of pulsating stars. The phenomena include not only period doubling cascades en route to chaos (detected in earlier studies) but also periodic windows within chaotic band, type-I and type-III intermittent behaviour, interior crisis bifurcation and others. Such phenomena are known in many textbook chaotic systems, from the simplest discrete logistic map, to more complex systems like Lorenz equations. We discuss the physical relevance of our models. Although except of period doubling such phenomena were not detected in any BL Her star, chaotic variability was claimed in several higher luminosity siblings of BL Her stars - RV Tau variables, and also in longer-period, luminous irregular pulsators. Our models may help to understand these poorly studied stars. Pa...

  17. Expression of Ty-lacZ fusions in Saccharomyces cerevisiae.

    OpenAIRE

    Bowen, B A; Fulton, A.M.; Tuite, M F; Kingsman, S M; Kingsman, A J

    1984-01-01

    We have determined the nucleotide sequence of about 520 bp spanning the 5' delta regions (Figure 1) of two Tyl elements. There is an open reading frame running out of the deltas for at least 180 nucleotides into the internal region of each element. The functional significance of these open reading frames has been tested by fusing them to a defective E.coli lacZ gene. Expression of B-galactosidase in yeast transformants containing these fusions shows that Tyl elements contain functional transl...

  18. 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…

  19. 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.

  20. 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.

  1. Radiocarbon measurements at LAC-UFF: Recent performance

    Science.gov (United States)

    Linares, Roberto; Macario, Kita D.; Santos, Guaciara M.; Carvalho, Carla; dos Santos, Hellen C.; Gomes, Paulo R. S.; Castro, Maikel D.; Oliveira, Fabiana M.; Alves, Eduardo Q.

    2015-10-01

    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 13C+/12C+ becomes erratic. Therefore, in order to maintain the AMS-δ13C values within reasonable values, so that fractionation corrections using the spectrometer 13C+/12C+ values does not affect the final 14C results, we are forced to limit the 12C- 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 14C 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.

  2. 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 ...

  3. 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...

  4. Soft X-ray spectrum of BL Lacertae object AO 0235+164 as a tracer of elemental abundances at z approximately 0.5

    Science.gov (United States)

    Madejski, Greg

    1994-01-01

    We report the soft X-ray spectrum of BL Lac object AO 0235+164, observed with the Einstein Observatory Imaging Proportional Counter (IPC). This object (z = 0.94) has an intervening galaxy (or a protogalactic disk) at z = 0.524 present in the line of sight, producing both radio and optical absorption lines in the background BL Lac continuum. The X-ray spectrum exhibits a substantial soft X-ray cutoff, corresponding to several times that expected from our own Galaxy; we interpret that excess cutoff as due to the intervening galaxy. The comparison of the hydrogen column density inferred from the 21 cm radio data and the X-ray absorption allows, in principle, the determination of the elemental abundances in the intervening galaxy. However, the uncertainties in both the H I spin temperature and X-ray spectral parameters only loosely restrict these abundances to be 2 +/- 1 solar, which even at the lower limit appears higher than that inferred from studies of samples of optical absoprtion-line systems.

  5. A lacZ reporter gene expression atlas for 313 adult KOMP mutant mouse lines

    OpenAIRE

    West, David B.; Pasumarthi, Ravi K.; Baridon, Brian; Djan, Esi; Trainor, Amanda; Stephen M Griffey; Engelhard, Eric K.; Rapp, Jared; LI, BOWEN; de Jong, Pieter J.; Lloyd, K. C. Kent

    2015-01-01

    Expression of the bacterial beta-galactosidase reporter gene (lacZ) in the vector used for the Knockout Mouse Project (KOMP) is driven by the endogenous promoter of the target gene. In tissues from KOMP mice, histochemical staining for LacZ enzyme activity can be used to determine gene expression patterns. With this technique, we have produced a comprehensive resource of gene expression using both whole mount (WM) and frozen section (FS) LacZ staining in 313 unique KOMP mutant mouse lines. Of...

  6. Activation of the lac genes of Tn951 by insertion sequences from Pseudomonas cepacia.

    OpenAIRE

    Wood, M S; Lory, C; Lessie, T G

    1990-01-01

    We have identified three transposable gene-activating elements from Pseudomonas cepacia on the basis of their abilities to increase expression of the lac genes of the broad-host-range plasmid pGC91.14 (pRP1::Tn951). When introduced into auxotrophic derivatives of P. cepacia 249 (ATCC 17616), this plasmid failed to confer the ability to utilize lactose. The lac genes of Tn951 were poorly expressed in P. cepacia and were not induced by isopropyl-beta-D-thiogalactopyranoside. Lac+ variants of th...

  7. 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.

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. Narrative report September, October, November, December, 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 September through December of 1946. The report begins by...

  14. 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...

  15. 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...

  16. Narrative report January, February, March, April, 1947 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 1947. The report begins by summarizing the...

  17. 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...

  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. Narrative report September, October, November, December, 1947 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 1947. The report begins by...

  20. 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...

  1. Narrative report May, June, July, August, 1947 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 1947. The report begins by summarizing the...

  2. 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...

  3. 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...

  4. Des Lacs National Wildlife Refuge : Annual Narrative Report : Calendar Year 1984

    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 1984 calendar year. The report begins with a summary...

  5. 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...

  6. Des Lacs National Wildlife Refuge : Annual Narrative Report : Calendar Year 1986

    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 1986 calendar year. The report begins with a summary...

  7. 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...

  8. Des Lacs National Wildlife Refuge : Annual Narrative Report : Calendar Year 1988

    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 1988 calendar year. The report begins with a summary...

  9. 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...

  10. 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...

  11. 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...

  12. Des Lacs National Wildlife Refuge: Annual narrative report: Calendar year 1993

    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 1993 calendar year. The report begins with a summary...

  13. Des Lacs National Wildlife Refuge[: Annual narrative report: Calendar year 1995

    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 1995 calendar year. The report begins with a summary...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. Rice Lake National Wildlife Refuge, Mille Lacs Refuge, Sandstone Unit: [Narrative report]: 1972

    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 1972 calendar year. The report begins by summarizing...

  20. Quarterly narrative report for Des Lacs National Wildlife Refuge [May-July, 1941

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Des Lacs Migratory Waterfowl Refuge outlines Refuge accomplishments from May through July of 1941. The report begins by summarizing the...

  1. 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,...

  2. 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...

  3. 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...

  4. [Development of Matt Welch's land : Unit #2 at Des Lacs National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Memorandum to the Acting Regional Director from Des Lacs National Wildlife Refuge concenring the proposed work to improve and developm the pasture area on Matt...

  5. 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...

  6. 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...

  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 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...

  9. 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...

  10. 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...

  11. 1956 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...

  12. 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...

  13. 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...

  14. 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.

  15. 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...

  16. 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.

  17. 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...

  18. Rice Lake National Wildlife Refuge, Mille Lacs Refuge, Sandstone Unit: [Narrative report: 1971

    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 1971 calendar year. The report begins by summarizing...

  19. Des Lacs National Wildlife Refuge : Annual Narrative Report : Calendar Year 1982

    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 1982 calendar year. The report begins with a summary...

  20. 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...

  1. Des Lacs National Wildlife Refuge : Annual Narrative Report : Calendar Year 1979

    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 1979 calendar year. The report begins with an introduction to...

  2. Des Lacs National Wildlife Refuge : Annual Narrative Report : Calendar Year 1981

    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 1981 calendar year. The report begins with a summary...

  3. Des Lacs National Wildlife Refuge : Annual Narrative Report : Calendar Year 1978

    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 1978 calendar year. The report begins with an introduction to...

  4. 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...

  5. 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...

  6. Chandra view of the warm-hot intergalactic medium toward 1ES 1553+113: Absorption-line detections and identifications. I

    OpenAIRE

    F. Nicastro; Barcons, Xavier; Paerels, F. B. S.

    2013-01-01

    We present the first results from our pilot 500 ks Chandra Low Energy Transmission Grating Large Program observation of the soft X-ray brightest source in the z ≳ 0.4 sky, the blazar 1ES 1553+113, aimed to secure the first uncontroversial detections of the missing baryons in the X-rays. We identify a total of 11 possible absorption lines, with single-line statistical significances between 2.2σ and 4.1σ. Six of these lines are detected at high single-line statistical significance (3.6 ≤ σ ≤ 4....

  7. New BVR Photometry of BL Camelopardalis

    Science.gov (United States)

    Joner, Michael D.

    2015-01-01

    New BVR photometry of the SX Phe star BL Camelopardalis has been secured with the 0.9 m reflector at the BYU West Mountain Observatory. The new data have been used to determine times of maximum light, standardize light curves in each of the three filters, and examine the frequencies that are currently detectable in the light curves from a single location.We acknowledge the Brigham Young University College of Physical and Mathematical Sciences as well as the Department of Physics and Astronomy for continued support of this and other research efforts currently being done at the West Mountain Observatory.

  8. OFDI between India and the LAC Region : A firm level motive analysis

    OpenAIRE

    Varma, Sumati; Nayyar, Rishika

    2014-01-01

    India and the Latin America and Caribbean (LAC) region have emerged as major growth drivers of the world economy in the last couple of decades. Trade and investment relations between these regions have traditionally been rather insignificant but have picked up in recent years. Since 2000, Indian companies have invested about $12 billion in the LAC region across various industries. This paper examines the important issue of the motives driving OFDI between the two regions. It uses content ana...

  9. 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 ...

  10. 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.

  11. eLac - Conceptual Model for Flood Management

    Science.gov (United States)

    Rata, Marius; Florentin Draghia, Aurelian; Drobot, Radu; Matreata, Marius; Corbus, Ciprian

    2015-04-01

    This article reviews the conceptual model of the decision support system (DSS) for flood management activities introduced in the scope of e-LAC project. Following the general system architecture which has an emphasize on the water management decision processes, hydrologic and hydraulic models are introduced and discussed according to their specific DSS integration potential. Three directions are discussed in dedicated sections corresponding to the main modules defined in the conceptual model : the Water Basin Management Module (mainly implements the management decision flow, but manages also data exchange between hydrologic modeling module and hydraulic modeling module, allow real time visualization for hydrological data), the Hydrologic Modeling Module (manages all the modeling functionalities of rainfalls - runoff processes, providing continuous hydrologic forecasts with a variable time-step depending on the actual basin situation) and the Hydraulic Modeling Module (computes the flood's waves routing having as boundary upstream conditions the discharge hydrographs, generated both by catchment's upper area, river tributaries and inter-basins, respectively the rating curves, water level hydrograph or water surface slope as downstream condition). The GIS concepts are contextually reviewed based on their use as geospatial database for water management modeling, integration within hydrologic time courses, hydraulic modeling (from both software and management perspective), expert knowledge or mathematical modeling results (knowledge database, rules).

  12. 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.

  13. Longterm Optical Monitoring of Bright BL Lacertae Objects with ATOM: Spectral Variability and Multiwavelength Correlations

    CERN Document Server

    Wierzcholska, Alicja; Stawarz, Łukasz; Wagner, Stefan; Hauser, Marcus

    2014-01-01

    Blazars are the established sources of an intense and variable non-thermal radiation extending from radio wavelengths up to HE and VHE gamma-rays. Understanding the spectral evolution of blazars in selected frequency ranges, as well as multi-frequency correlations in various types of blazar sources, is of a primary importance for constraining the blazar physics. Here we present the results of a long-term optical monitoring of a sample of 30 blazars of the BL Lac type. We study the optical color-magnitude correlation patterns emerging in the analyzed sample, and compare the optical properties of the targets with the high-energy gamma-ray and high-frequency radio data. The optical observations were carried out in R and B filters using ATOM telescope. Each object was observed during at least 20 nights in the period 2007-2012. We find significant global color-magnitude correlations in 40 % of the sample. The sources which do not display any clear chromatism often do exhibit bluer-when-brighter (bwb) behavior but ...

  14. Studies of the Jet in BL Lacertae. II. Superluminal Alfv\\'en Waves

    CERN Document Server

    Cohen, M H; Arshakian, T G; Clausen-Brown, E; Homan, D C; Hovatta, T; Kovalev, Y Y; Lister, M L; Pushkarev, A B; Richards, J L; Savolainen, T

    2014-01-01

    Ridge lines on the pc-scale jet of the active galactic nucleus BL Lac display transverse patterns that move superluminally downstream. The patterns are not ballistic, but are analogous to waves on a whip. Their apparent speeds $\\beta_\\mathrm{app}$ (units of $c$) range from 4.2 to 13.5, corresponding to $\\beta_\\mathrm{wave}^\\mathrm{gal}= 0.981 - 0.998$ in the galaxy frame. We show that the magnetic field in the jet is well-ordered with a strong transverse component, and assume that it is helical and that the transverse patterns are longitudinal Alfv\\'en waves. The wave-induced transverse speed of the jet is non-relativistic ($\\beta_\\mathrm{tr}^\\mathrm{gal}\\sim 0.09$) and in agreement with our assumption of low-amplitude waves. In 2010 the wave activity subsided and the jet displayed a mild wiggle that had a complex oscillatory behavior. The waves are excited by changes in the position angle of the recollimation shock, in analogy to exciting a wave on a whip by shaking it. Simple models of the system are presen...

  15. The first Fermi multifrequency campaign on BL Lacertae: characterizing the low-activity state of the eponymous blazar

    CERN Document Server

    Abdo, A A

    2011-01-01

    We report on observations of BL Lacertae during the first 18 months of Fermi-LAT science operations and present results from a 48-day multifrequency coordinated campaign from 2008 August 19 to 2008 October 7. The radio to gamma-ray behavior of BL Lac is unveiled during a low activity state thanks to the coordinated observations of radio-band (Metsahovi and VLBA), near-IR/optical (Tuorla, Steward, OAGH and MDM) and X-ray (RXTE and Swift) observatories. No variability was resolved in gamma-rays during the campaign, and the brightness level was 15 times lower than the level of the 1997 EGRET outburst. Moderate and uncorrelated variability has been detected in UV and X-rays. The X-ray spectrum is found to be concave indicating the transition region between the low and high energy component of the spectral energy distribution (SED). VLBA observation detected a synchrotron spectrum self-absorption turnover in the innermost part of the radio jet appearing to be elongated and inhomogeneous, and constrained the averag...

  16. 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

  17. 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.

  18. Activation of the lac genes of Tn951 by insertion sequences from Pseudomonas cepacia.

    Science.gov (United States)

    Wood, M S; Lory, C; Lessie, T G

    1990-04-01

    We have identified three transposable gene-activating elements from Pseudomonas cepacia on the basis of their abilities to increase expression of the lac genes of the broad-host-range plasmid pGC91.14 (pRP1::Tn951). When introduced into auxotrophic derivatives of P. cepacia 249 (ATCC 17616), this plasmid failed to confer the ability to utilize lactose. The lac genes of Tn951 were poorly expressed in P. cepacia and were not induced by isopropyl-beta-D-thiogalactopyranoside. Lac+ variants of the pGC91.14-containing strains which formed beta-galactosidase at high constitutive levels as a consequence of transposition of insertion sequences from the P. cepacia genome to sites upstream of the lacZ gene of Tn951 were isolated. Certain of the elements also increased gene expression in other bacteria. For example, IS407 strongly activated the lacZ gene of Tn951 in Pseudomonas aeruginosa and Escherichia coli, and IS406 (but not IS407) did so in Zymomonas mobilis. The results indicate that IS elements from P. cepacia have potential for turning on the expression of foreign genes in a variety of gram-negative bacteria. PMID:2156800

  19. 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.

  20. Analysis of the activity of the blazar BL Lacertae over the period 1998-2011

    Science.gov (United States)

    Strigunov, K. S.; Zhovtan, A. V.

    2016-07-01

    In 1998-2011 the blazar (active galactic nucleus) BL Lacertae was observed at Crimean Astrophysical Observatory (CrAO) with the second-generation GT-48 Cherenkov telescope at energies >1 TeV with a total significance of 11.8σ. More than 20 flares and a fourfold change in yearly mean fluxes (>1 TeV) were recorded. The optical ( B band) data obtained at CrAO and the TeV data are shown to correlate in some time intervals. The optical data are also compared with the X-ray RXTE/ASM (2-10 keV) data. In addition, the data from GT-48 are compared with the gamma-ray fluxes recorded by the Fermi LAT space telescope (0.1-300 GeV). The 2009 flare at TeV and Fermi energies has been studied. As a result, it has been found that as the activity rises the increase in flux at high energies exceeds its increase at low energies. This conclusion may be related to the conversion mechanism of particle acceleration. This is consistent with the results of studies for a similar object, 1ES 1426+428.

  1. Quasi-BL-Algebras and Their Equivalence with BL-Algebras%QBL-代数及其与BL-代数的等价性

    Institute of Scientific and Technical Information of China (English)

    高李红; 吴洪博

    2011-01-01

    By means of the characters that the basic logic algebra BL is matched with the fuzzy propositional logic system BL, the new logic algebraic structure called QBL-algebra has been established from the algebraizing of the axioms of fuzzy propositional logic system BL.The equivalence between the QBL-algebras and the BL-logic algebras have been proved.Consequentely, the presentative theorem of the BL-logic algebras has been given with two kinds of binary operations (×),→ on a general set.%根据命题逻辑系统BL与基础逻辑代数BL在语义方面相匹配的特征,将基础逻辑系统BL中的部分公理代数化,建立一种新的代数结构QBL-代数,并证明了QBL-代数与BL-代数的等价性,以两种二元运算(╳),→为基础在一般集合上给出了基础逻辑代数BL的表示定理.

  2. 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...

  3. Quasi-Periodic Oscillations of ~ 15 minutes in the Optical Light Curve of the BL Lac S5 0716+714

    CERN Document Server

    Rani, Bindu; Joshi, U C; Ganesh, S; Wiita, Paul J

    2010-01-01

    Over the course of three hours on 27 December 2008 we obtained optical (R-band) observations of the blazar S5 0716+714 at a very fast cadence of 10 s. Using several different techniques we find fluctuations with an approximately 15-minute quasi-period to be present in the first portion of that data at a > 3 sigma confidence level. This is the fastest QPO that has been claimed to be observed in any blazar at any wavelength. While this data is insufficient to strongly constrain models for such fluctuations, the presence of such a short timescale when the source is not in a very low state seems to favor the action of turbulence behind a shock in the blazar's relativistic jet.

  4. Lac repressor: Crystallization of intact tetramer and its complexes with inducer and operator DNA

    International Nuclear Information System (INIS)

    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 α = γ = 90 degree and β = 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 β-D-thiogalactoside, suggesting a conformational change in the repressor-operator complex

  5. 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.

  6. Effects of lac insect honeydew on the diversity of ground-dwelling ants in lac plantation%紫胶虫蜜露对地表蚂蚁多样性的影响

    Institute of Scientific and Technical Information of China (English)

    卢志兴; 陈又清; 李巧; 王思铭; 刘春菊; 张威

    2012-01-01

    By the method of pitfall trapping, an investigation was conducted on the diversity of ground-dwelling ants in a lac plantation in Yayi Town of Mojiang County, Yunnan Province of Southwest China in December 2009-May 2010, aimed to understand the effects of lac insect honey-dew on the diversity of ground-dwelling ants. The presence or absence of lac insect honeydew and its dynamics all affected the species composition, abundance, and diversity of ground-dwelling ants. In the lac plantation with lac insect hosting, a total of 4953 ant individuals were collected, belonging to 34 species, 23 genera, and 5 subfamilies of Formicidae; whereas in the lac plantation without lac insect hosting, a total of 2416 ant individuals were collected, belonging to 30 species, 20 genera, and 5 subfamilies of Formicidae. The relative abundance, species richness (5) , and ACE index in the lac plantation with lac insect hosting were higher than those in the lac plantation without lac insect hosting, and the common species and indicator species of ground-dwelling ants in the lac plantation with lac insect hosting differed from those in the lac plantation without lac insect hosting, suggesting that lac insect hosting altered the community structure of ground-dwelling ants. The adult lac insects excreted larger quantity of honeydew than the larval lac insects, and the relative abundance, S, and ACE index of ground-dwelling ants were higher at the adult stage than at the larval stage of lac insects. The common species and indicator species of ground-dwelling ants also had great differences between the two stages of lac insects.%2009年12月至2010年5月,采用陷阱法在云南省墨江县雅邑乡调查了紫胶林地表蚂蚁群落多样性,分析了紫胶虫蜜露对地表蚂蚁多样性的影响.结果表明:紫胶虫蜜露资源的有无及变动对地表蚂蚁群落物种组成、多度及多样性均产生影响.在紫胶林样地共采集蚂蚁标本4953头,隶属5亚科23属34种,

  7. Behavioral profiles of three C57BL/6 substrains

    Directory of Open Access Journals (Sweden)

    Naoki Matsuo

    2010-06-01

    Full Text Available C57BL/6 inbred strains of mice are widely used in knockout and transgenic research. To evaluate the loss-of-function and gain-of-function effects of the gene of interest, animal behaviors are often examined. However, an issue of C57BL/6 substrains that is not always appreciated is that behaviors are known to be strongly influenced by genetic background. To investigate the behavioral characteristics of C57BL/6 substrains, we subjected C57BL/6J, C57BL/6N, and C57BL/6C mice to a behavior test battery. We performed both a regular-scale analysis, in which experimental conditions were tightly-controlled, and meta-analysis from large number of behavioral data that we have collected so far through the comprehensive behavioral test battery applied to 700-2,200 mice in total. Significant differences among the substrains were found in the results of various behavioral tests, including the open field, rotarod, elevated plus maze, prepulse inhibition, Porsolt forced swim, and spatial working memory version of the 8-arm radial maze. Our results show a divergence of behavioral performance in C57BL/6 substrains, which suggest that small genetic differences may have a great influence on behavioral phenotypes. Thus, the genetic background of different substrains should be carefully chosen, equated, and considered in the interpretation of mutant behavioral phenotypes.

  8. 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.

  9. Charge coupled devices (CCD) photometry and long-term optical variability of gamma-ray-loud BL Lacertae object Mkn 421

    Institute of Scientific and Technical Information of China (English)

    Zhang Xiong; Zheng Yong-Gang; Zhang Hao-Jing; Hu Shao-Ming; Xie Zhao-Hua

    2006-01-01

    Evidence for the long-term optical curve variability and colour behaviour of the BL Lac object Mkn 421 is presented.Our results show that the amplitude of the optical variations of Mkn 421 is only about ΔB=4.7 magnitude in the B-band for its photometric history from 1899 to 2002. The results of optical photometric monitoring of the Mkn 421 from April 2000 to Jan 2002 are provided. During our observation, Mkn 421 shows significant rapid variations and exhibits short time variability of 2.42 hours in the B band. A strong correlation between the B - V colour index and the magnitude in the B band is found. Our charge coupled device (CCD) photometry of Mkn 421 shows that the measured results are in good agreement with the predicted optical variability period of about 23 years.

  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. 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...

  12. 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.

  13. 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 ...

  14. 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

  15. 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.

  16. Expression of Porcine Interleukin-2 and Porcine Interleukin-6 and Their Adjuvant Effects on Gene Deleted Vaccine of Pseudorabies Virus (TK-/gG-/LacZ+)

    Institute of Scientific and Technical Information of China (English)

    YAN Lin; HE Qi-gai; CHEN Huan-chun; XIAO Shao-bo; WU Mei-zhou; LU Jian-qiang; HAN Li

    2003-01-01

    Porcine interleukin-2 and porcine interleukin-6 cDNA sequences were cloned into the expressing vectors pET-28a and pGEX-KG respectively. They were expressed in E.coli BL21 (DE3) with high-level production. The gene deleted vaccine of pseudorabies virus Ea strain (TK-/gG-/LacZ+) was mixed with the two different purified recombinant proteins each, or both, with the doses of 2, 5 or 10 μg ml-1. Ten groups of pseudorabies negative antibody swines were immuned twice with tested vaccines with different doses, or control vaccine, respectively. The antibody titers of the test groups were detected by neutralization test, and the daily weight gains of swines were calculated and analyzed statistically. In the study, all the neutralizing antibody titers in test groups were higher than the control group, and the recombinant proteins appeared a dose dependent adjuvant effect. The tested vaccines with 2 μg ml-1 pIL-2 and with 10 μg ml-1 pIL-2/pIL-6 got significant and extremely significant differences, compared with the vaccines without pILs. The difference of the daily weight gain indicated the potential positive influence of pIL-2 and pIL-6 on immune protection.

  17. Positive control of lac operon expression in vitro by guanosine 5'-diphosphate 3'-diphosphate.

    Science.gov (United States)

    Primakoff, P; Artz, S W

    1979-04-01

    Maximal expression of the Escherichia coli lactose operon in a coupled in vitro transcription-translation system from a Salmonella typhimurium relA mutant was strongly dependent upon addition of guanosine 5'-diphosphate 3'-diphosphate (ppGpp). Without added ppGpp, at saturating 3',5'-cyclic AMP (cAMP) concentrations, synthesis of beta-galactosidase (beta-D-galactoside galactohydrolase, EC 3.2.1.23) was reproducibly only 5-7% of that which can be obtained with 0.5-0.8 mM ppGpp. Experiments in which transcription was uncoupled from translation indicated that this 14- to 20-fold stimulation by ppGpp occurred at the level of transcription. When coupled beta-galactosidase synthesis was primed with a template containing a well-characterized mutant lac promoter (lacP(r)L8UV5), the dependence on ppGpp was greatly reduced. This result provides an important experimental control previously unavailable for verifying the significance of ppGpp effects on gene regulation in vitro; it indicates that activation of lacP(+) expression by ppGpp is specifically an effect of increased transcription initiations. Furthermore, the large ppGpp stimulation of lacP(+) DNA enabled the level of expression of this template to approach that of lacP(r)L8UV5 DNA, an observation expected from results in vivo but not obtained with other transcription-translation systems in vitro. The importance of these results is considered with respect to previous ideas on the physiological role of ppGpp as a supercontrol molecule in bacterial regulation. PMID:109832

  18. 云县紫胶虫相关特性及放养技术对紫胶生产的影响%Effects of Relevant Characteristics of Yunxian Lac Insect and Stocking Technology on Lac Production

    Institute of Scientific and Technical Information of China (English)

    严世葵

    2013-01-01

    According to the morphological characteristics of the lac insect, living habits, biological characteristics and pupae scattered law, various technical aspects of the lac stocking and post-stocking management and harvesting were elaborated, which lay a foundation for lac production.%根据紫胶虫的形态特征、生活习性、生物学特性及蛹散规律,阐述了紫胶虫放养中的各个技术环节及放养后的管理和紫胶的采收,为紫胶生产奠定了基础.

  19. Measurement of Ligand-Induced Activation in Single Viable T Cells Using the lacZ Reporter Gene

    Science.gov (United States)

    Karttunen, Jaana; Shastri, Nilabh

    1991-05-01

    We have used the bacterial β-galactosidase gene (lacZ) as a reporter gene for the rapid measurement of T-cell antigen receptor (TCR)-mediated activation of individual T cells. The reporter construct contained the lacZ gene under the control of the nuclear factor of activated T cells (NF-AT) element of the human interleukin 2 enhancer [Fiering, S., Northrop, J. P., Nolan, G. P., Matilla, P., Crabtree, G. R. & Herzenberg, L. A. (1990) Genes Dev. 4, 1823-1834]. The activity of the intracellular lacZ enzyme was analyzed by flow cytometric measurement of fluorescein accumulation in cells loaded with the fluorogenic β-galactosidase substrate fluorescein di-β-D-galactopyranoside. As a model system, the T-cell hybridoma BO4H9.1, which is specific for the lysozyme peptide (amino acids 74-88)/A^b complex, was transfected with the NF-AT-lacZ construct. lacZ activity was induced in 50-100% of the transfectant cells following exposure to pharmacological agents, to the physiological peptide/major histocompatibility complex ligand, or to other TCR-specific stimuli. Interestingly, increasing concentrations of the stimulus increased the fraction of lacZ^+ cells, but not the level of lacZ activity per cell. Even under widely varying levels of stimulus, the level of lacZ activity in individual lacZ^+ cells remained within a remarkably narrow range. These results demonstrate that TCR-mediated activation can be readily measured in single T cells and strongly suggest that, once committed to activation, the level of NF-AT transcriptional activity in individual T cells is independent of the form or concentration of stimulus. This assay is likely to prove useful for the study of early activation events in individual T cells and of TCR ligands.

  20. 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

  1. Use of urea and glycine betaine to quantify coupled folding and probe the burial of DNA phosphates in lac repressor-lac operator binding.

    Science.gov (United States)

    Hong, Jiang; Capp, Mike W; Saecker, Ruth M; Record, M Thomas

    2005-12-27

    Thermodynamic analysis of urea-biopolymer interactions and effects of urea on folding of proteins and alpha-helical peptides shows that urea interacts primarily with polar amide surface. Urea is therefore predicted to be a quantitative probe of coupled folding, remodeling, and other large-scale changes in the amount of water-accessible polar amide surface in protein processes. A parallel analysis indicates that glycine betaine [N,N,N-trimethylglycine (GB)] can be used to detect burial or exposure of anionic (carboxylate, phosphate) biopolymer surface. To test these predictions, we have investigated the effects of these solutes (0-3 m) on the formation of 1:1 complexes between lac repressor (LacI) and its symmetric operator site (SymL) at a constant KCl molality. Urea reduces the binding constant K(TO) [initial slope dlnK(TO)/dm(urea) = -1.7 +/- 0.2], and GB increases K(TO) [initial slope dlnK(TO)/dm(GB) = 2.1 +/- 0.2]. For both solutes, this derivative decreases with an increase in solute concentration. Analysis of these initial slopes predicts that (1.5 +/- 0.3) x 10(3) A2 of polar amide surface and (4.5 +/- 1.0) x 10(2) A2 of anionic surface are buried in the association process. Analysis of published structural data, together with modeling of unfolded regions of free LacI as extended chains, indicates that 1.5 x 10(3) A2 of polar amide surface and 6.3 x 10(2) A2 of anionic surface are buried in complexation. Quantitative agreement between structural and thermodynamic results is obtained for amide surface (urea); for anionic surface (GB), the experimental value is approximately 70% of the structural value. For LacI-SymL binding, two-thirds of the structurally predicted change in amide surface (1.0 x 10(3) A2) occurs outside the protein-DNA interface in protein-protein interfaces formed by folding of the hinge helices and interactions of the DNA binding domain (DBD) with the core of the repressor. Since urea interacts principally with amide surface, it is

  2. KEPLER OBSERVATIONS OF RAPID OPTICAL VARIABILITY IN THE BL LACERTAE OBJECT W2R1926+42

    Energy Technology Data Exchange (ETDEWEB)

    Edelson, R.; Mushotzky, R. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Vaughan, S. [X-ray and Observational Astronomy Group, Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Scargle, J. [Astrobiology and Space Science Division, NASA Ames Research Center, Moffet Field, CA 94035 (United States); Gandhi, P. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Malkan, M. [Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, CA 90095-1547 (United States); Baumgartner, W., E-mail: redelson@astro.umd.edu [Laboratory for High Energy Astrophysics, NASA/GSFC, Code 662, Greenbelt, MD 20771 (United States)

    2013-03-20

    We present the first Kepler monitoring of a strongly variable BL Lac, W2R1926+42. The light curve covers 181 days with {approx}0.2% errors, 30 minute sampling and >90% duty cycle, showing numerous {delta}I/I > 25% flares over timescales as short as a day. The flux distribution is highly skewed and non-Gaussian. The variability shows a strong rms-flux correlation with the clearest evidence to date for nonlinearity in this relation. We introduce a method to measure periodograms from the discrete autocorrelation function, an approach that may be well-suited to a wide range of Kepler data. The periodogram is not consistent with a simple power-law, but shows a flattening at frequencies below 7 Multiplication-Sign 10{sup -5} Hz. Simple models of the power spectrum, such as a broken power law, do not produce acceptable fits, indicating that the Kepler blazar light curve requires more sophisticated mathematical and physical descriptions than currently in use.

  3. KEPLER OBSERVATIONS OF RAPID OPTICAL VARIABILITY IN THE BL LACERTAE OBJECT W2R1926+42

    International Nuclear Information System (INIS)

    We present the first Kepler monitoring of a strongly variable BL Lac, W2R1926+42. The light curve covers 181 days with ∼0.2% errors, 30 minute sampling and >90% duty cycle, showing numerous δI/I > 25% flares over timescales as short as a day. The flux distribution is highly skewed and non-Gaussian. The variability shows a strong rms-flux correlation with the clearest evidence to date for nonlinearity in this relation. We introduce a method to measure periodograms from the discrete autocorrelation function, an approach that may be well-suited to a wide range of Kepler data. The periodogram is not consistent with a simple power-law, but shows a flattening at frequencies below 7 × 10–5 Hz. Simple models of the power spectrum, such as a broken power law, do not produce acceptable fits, indicating that the Kepler blazar light curve requires more sophisticated mathematical and physical descriptions than currently in use.

  4. CHANDRA VIEW OF THE WARM-HOT INTERGALACTIC MEDIUM TOWARD 1ES 1553+113: ABSORPTION-LINE DETECTIONS AND IDENTIFICATIONS. I

    Energy Technology Data Exchange (ETDEWEB)

    Nicastro, F.; Zappacosta, L. [Osservatorio Astronomico di Roma-INAF, Via di Frascati 33, I-00040 Monte Porzio Catone, RM (Italy); Elvis, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., MS-04, Cambridge, MA 02138 (United States); Krongold, Y. [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Mexico City Mexico (Mexico); Mathur, S.; Gupta, A. [Ohio State University, Columbus, OH (United States); Danforth, C.; Shull, J. M. [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Barcons, X. [Instituto de Fisica de Cantabria (CSIC-UC), E-39005 Santander (Spain); Borgani, S. [Dipartimento di Astronomia dell' Universita di Trieste, Via G.B. Tiepolo 11, I-34131 Trieste (Italy); Branchini, E. [Dipartimento di Fisica ' ' E. Amaldi' ' , Universita degli Studi ' ' Roma Tre' ' , via della Vasca Navale 84, I-00146 Roma (Italy); Cen, R. [Princeton University Observatory, Princeton, NJ 08544 (United States); Dave, R. [Astronomy Department, University of Arizona, Tucson, AZ 85721 (United States); Kaastra, J. [SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA, Utrecht (Netherlands); Paerels, F. [Columbia Astrophysics Laboratory and Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Piro, L. [INAF-IAPS, Via del Fosso del Cavaliere 100, I-00133 Roma (Italy); Takei, Y. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)

    2013-06-01

    We present the first results from our pilot 500 ks Chandra Low Energy Transmission Grating Large Program observation of the soft X-ray brightest source in the z {approx}> 0.4 sky, the blazar 1ES 1553+113, aimed to secure the first uncontroversial detections of the missing baryons in the X-rays. We identify a total of 11 possible absorption lines, with single-line statistical significances between 2.2{sigma} and 4.1{sigma}. Six of these lines are detected at high single-line statistical 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 far-ultraviolet (FUV) signposts. Three of these lines are consistent with metal absorption at z {approx_equal} 0, and we identify them with Galactic O I and C II. The remaining eight lines may be imprinted by intervening absorbers and are all consistent with being high-ionization counterparts of FUV H I and/or O VI intergalactic medium signposts. In particular, five of these eight possible intervening absorption lines (single-line statistical significances of 4.1{sigma}, 4.1{sigma}, 3.9{sigma}, 3.8{sigma}, and 2.7{sigma}), are identified as C V and C VI K{alpha} absorbers belonging to three WHIM systems at z{sub X} = 0.312, z{sub X} = 0.237, and (z{sub X} ) = 0.133, which also produce broad H I (and O VI for the z{sub X} = 0.312 system) absorption in the FUV. For two of these systems (z{sub X} = 0.312 and 0.237), the Chandra X-ray data led the a posteriori discovery of physically consistent broad H I associations in the FUV (for the third system the opposite applies), so confirming the power of the X-ray-FUV synergy for WHIM studies. The true statistical significances of these three X-ray absorption systems, after properly accounting for the number of redshift trials, are 5.8{sigma} (z{sub X} = 0.312; 6.3{sigma} if the low-significance O V and C V K{beta} associations are considered), 3.9{sigma} (z

  5. Chandra View of the Warm-hot Intergalactic Medium toward 1ES 1553+113: Absorption-line Detections and Identifications. I.

    Science.gov (United States)

    Nicastro, F.; Elvis, M.; 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.

    2013-06-01

    We present the first results from our pilot 500 ks Chandra Low Energy Transmission Grating Large Program observation of the soft X-ray brightest source in the z >~ 0.4 sky, the blazar 1ES 1553+113, aimed to secure the first uncontroversial detections of the missing baryons in the X-rays. We identify a total of 11 possible absorption lines, with single-line statistical significances between 2.2σ and 4.1σ. Six of these lines are detected at high single-line statistical significance (3.6 X-ray lines detected at higher significance and/or far-ultraviolet (FUV) signposts. Three of these lines are consistent with metal absorption at z ~= 0, and we identify them with Galactic O I and C II. The remaining eight lines may be imprinted by intervening absorbers and are all consistent with being high-ionization counterparts of FUV H I and/or O VI intergalactic medium signposts. In particular, five of these eight possible intervening absorption lines (single-line statistical significances of 4.1σ, 4.1σ, 3.9σ, 3.8σ, and 2.7σ), are identified as C V and C VI Kα absorbers belonging to three WHIM systems at zX = 0.312, zX = 0.237, and langzX rang = 0.133, which also produce broad H I (and O VI for the zX = 0.312 system) absorption in the FUV. For two of these systems (zX = 0.312 and 0.237), the Chandra X-ray data led the a posteriori discovery of physically consistent broad H I associations in the FUV (for the third system the opposite applies), so confirming the power of the X-ray-FUV synergy for WHIM studies. The true statistical significances of these three X-ray absorption systems, after properly accounting for the number of redshift trials, are 5.8σ (zX = 0.312; 6.3σ if the low-significance O V and C V Kβ associations are considered), 3.9σ (zX = 0.237), and 3.8σ (langzX rang = 0.133), respectively.

  6. R-parity Conserving Minimal SUSY $B-L$ Model

    CERN Document Server

    Okada, Nobuchika

    2016-01-01

    We propose a simple gauged U(1)$_{B-L}$ extension of the minimal supersymmetric Standard Model (MSSM), where R-parity is conserved as usual in the MSSM. The global $B-L$ (baryon number minus lepton number) symmetry in the MSSM is gauged and three MSSM gauge-singlet chiral multiplets with a unit $B-L$ charge are introduced, ensuring the model free from gauge and gravitational anomalies. We assign an odd R-parity for two of the new chiral multiplets and hence they are identified with the right-handed neutrino superfields, while an even R-parity is assigned to the other one ($\\Phi$). The scalar component of $\\Phi$ plays the role of a Higgs field to break the U(1)$_{B-L}$ symmetry through its negative mass squared, which is radiatively generated by the renormalization group running of soft supersymmetry (SUSY) breaking parameters from a high energy. This radiative U(1)$_{B-L}$ symmetry breaking leads to its breaking scale being at the TeV naturally. Because of our novel R-parity assignment, three light neutrinos ...

  7. Unifying the electroweak and B-L interactions

    CERN Document Server

    Dong, P V

    2015-01-01

    We argue that the gauge symmetry which includes SU(3)_L as a higher weak-isospin symmetry is manifestly given by SU(3)_C\\otimes SU(3)_L\\otimes U(1)_X\\otimes U(1)_N, where the last two factors determine the electric charge and B-L, respectively. This theory not only provides a consistent unification of the electroweak and B-L interactions, but also gives insights in dark matter, neutrino masses, and inflation. The dark matter belongs to a class of new particles that have wrong B-L numbers, and is stabilized due to a newly-realized W-parity as residual gauge symmetry. The B-L breaking field is important to define the W-parity, seesaw scales, and inflaton. Furthermore, the number of fermion generations and the electric charge quantization are explained naturally. We also show that the previous 3-3-1 models are only an effective theory as the B-L charge and the unitarity argument are violated. This work substantially generalizes our recently-proposed 3-3-1-1 model.

  8. Rôle et place du riz pluvial dans les exploitations du lac Alaotra

    OpenAIRE

    Penot, E.; Domas, R.; Andriamalala, H.; Hyac, P.; Dupin, B.; Durand, C; Nave, S.; Rabenandro, T. H.; Rasolomanjaka, J.

    2009-01-01

    International audience La région de l'Alaotra repose sur un plateau situé à 750 mètres d'altitude avec au cœur de la plaine le lac Alaotra. La surface cultivée en riziculture est estimée à 148 500 ha en 2000 (FAO/UPDR, 2000), dont 75-80 000 ha dans la cuvette du Lac et plus de 65-70 000 ha au sud et dans les zones en périphérie, qui constitue 10% de la surface rizicole nationale pour seulement 4% des riziculteurs malgaches. Cette région réalise 33% de la valeur ajoutée de l'ensemble de la ...

  9. 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...

  10. 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...

  11. 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...

  12. Etude du comportement biogéochimique du carbone dans le lac Kivu au nord-ouest du Rwanda

    OpenAIRE

    Rwabuhungu Rwatangabo, Digne

    2008-01-01

    RésuméLe Rift Est-Africain comprend plusieurs grands lacs, dont le lac Kivu situé entre 1°34’et 2°30’ de latitude Sud et compris entre 28°50’ et 29°23’ de longitude Est. Ce lac,localisé au nord-ouest du Rwanda à la frontière avec la République Démocratique duCongo, présente une spécificité unique au monde: ses eaux profondes contiennentune gigantesque quantité de gaz dissous (3/4 de dioxyde de carbone (CO2), 1/4 degaz méthane (CH4)).Les études antérieures indiquent que les eaux du lac Kivu pr...

  13. Comprehensive Conservation Plan: Des Lacs National Wildlife Refuge, J. Clark Salyer National Wildlife Refuge, Upper Souris National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Comprehensive Conservation Plan (CCP) was written to guide management on Des Lacs NWR, J. Clark Salyer NWR, and Upper Souris NWR for the next 15 years. This...

  14. 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...

  15. 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'...

  16. Statistical analysis of the temporal properties of BL Lacertae

    Science.gov (United States)

    Guo, Yu Cheng; Hu, Shao Ming; Li, Yu Tong; Chen, Xu

    2016-08-01

    A comprehensive temporal analysis has been performed on optical light curves of BL Lacertae in the B, V and R bands. The light curves were denoised by Gaussian smoothing and decomposed into individual flares using an exponential profile. The asymmetry, duration, peak flux and equivalent energy output of flares were measured and the frequency distributions presented. Most optical flares of BL Lacertae are highly symmetric, with a weak tendency towards gradual rises and rapid decays. The distribution of flare durations is not random, but consistent with a gamma distribution. Peak fluxes and energy outputs of flares all follow a log-normal distribution. A positive correlation is detected between flare durations and peak fluxes. The temporal properties of BL Lacertae provide evidence of the stochastic magnetohydrodynamic process in the accretion disc and jet.The results presented here can serve as constraints on physical models attempting to interpret blazar variations.

  17. 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.

  18. Monitoring of the Lac Bam Wetland Extent Using Dual-Polarized X-Band SAR Data

    OpenAIRE

    Linda Moser; Andreas Schmitt; Anna Wendleder; Achim Roth

    2016-01-01

    Wetlands in semi-arid Africa are vital as water resource for local inhabitants and for biodiversity, but they are prone to strong seasonal fluctuations. Lac Bam is the largest natural freshwater lake in Burkina Faso, its water is mixed with patches of floating or flooded vegetation, and very turbid and sediment-rich. These characteristics as well as the usual cloud cover during the rainy season can limit the suitability of optical remote sensing data for monitoring purposes. This study demons...

  19. 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...

  20. MINNESOTA V. MILLE LACS: GATEWAY TO TRIBAL/STATE RESOURCE MANAGEMENT

    OpenAIRE

    Gonzalez, Mark J.

    2000-01-01

    Minnesota v. Mille Lacs Band of Chippewa Indians is the United States Supreme Court's most recent decision to focus on the continued existence of tribal off-reservation hunting, fishing, and gathering rights (usufructuary rights) as guaranteed by 19th century treaties entered into between the Lake Superior Chippewa and the federal government. This paper addresses three issues. First, a fundamental flaw with the Petitioner's position is a misconceptualization of the legal theory that governs I...

  1. 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...

  2. Engineering a portable riboswitch-LacP hybrid device for two-way gene regulation.

    Science.gov (United States)

    Jin, Ye; Huang, Jian-Dong

    2011-10-01

    Riboswitches are RNA-based regulatory devices that mediate ligand-dependent control of gene expression. However, there has been limited success in rationally designing riboswitches. Moreover, most previous riboswitches are confined to a particular gene and only perform one-way regulation. Here, we used a library screening strategy for efficient creation of ON and OFF riboswitches of lacI on the chromosome of Escherichia coli. We then engineered a riboswitch-LacP hybrid device to achieve portable gene control in response to theophylline and IPTG. Moreover, this device regulated target expression in a 'two-way' manner: the default state of target expression was ON; the expression was switched off by adding theophylline and restored to the ON state by adding IPTG without changing growth medium. We showcased the portability and two-way regulation of this device by applying it to the small RNA CsrB and the RpoS protein. Finally, the use of the hybrid device uncovered an inhibitory role of RpoS in acetate assimilation, a function which is otherwise neglected using conventional genetic approaches. Overall, this work establishes a portable riboswitch-LacP device that achieves sequential OFF-and-ON gene regulation. The two-way control of gene expression has various potential scientific and biotechnological applications and helps reveal novel gene functions. PMID:21803790

  3. 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.

  4. Von Blüten, Göttern und Gelehrten

    OpenAIRE

    Zotter, Astrid

    2013-01-01

    Der Sanskrittext Puṣpacintāmaṇi (PuCi) behandelt Blüten als Darbringungen (upacāra) im wichtigsten hinduistischen Verehrungsritual, der pūjā. In ca. 400 Strophen werden über 200 Namen von Blüten genannt und für verschiedene Gottheiten und pūjās als geeignete oder ungeeignete Gaben vorgeschrieben. Der Text ist eine Kompilation (Nibandha), in der die Inhalte aus 47 namentlich genannten Quellentexten referiert werden. Ziel der Dissertation ist es nicht nur, diesen Text, der 1966 zum ersten Ma...

  5. Kartlegging av marin bløtbunnsfauna - Metodeutvikling i hydrolittoralsonen

    OpenAIRE

    Haugen, Grethe Sundet

    2016-01-01

    Det er gjort få kvalitative undersøkelser på bløtbunnssamfunnet i hydrolittoralen i Norge. I denne studien ble artssammensetningen i littoralsonen fra tre forskjellige bløtbunnsstrender i Sør-Trøndelag undersøkt ved en enkel innsamlingsmetode. Innsamlingsmetoden hadde fokus på å observere og registrere fysiske miljøvariabler som bølgeeksponering og kornstørrelse, samt å observere å samle inn epi- og infauna som var tilstede i fjæra ved lavvann. Erfaringer fra felt- og laboratoriearbeidet har ...

  6. Probing classically conformal $B-L$ model with gravitational waves

    CERN Document Server

    Jinno, Ryusuke

    2016-01-01

    We study the cosmological history of the classical conformal $B-L$ gauge extension of the standard model, in which the physical scales are generated via the Coleman-Weinberg-type symmetry breaking. Especially, we consider the thermal phase transition of the U$(1)_{B-L}$ symmetry in the early universe and resulting gravitational-wave production. Due to the classical conformal invariance, the phase transition tends to be a first-order one with ultra-supercooling, which enhances the strength of the produced gravitational waves. We show that, requiring (1) U$(1)_{B-L}$ is broken after the reheating, (2) the $B-L$ gauge coupling does not blow up below the Planck scale, (3) the thermal phase transition completes in almost all the patches in the universe, the gravitational wave spectrum can be as large as $\\Omega_{\\rm GW} \\sim 10^{-8}$ at the frequency $f \\sim 0.01$-$1$Hz for some model parameters, and a vast parameter region can be tested by future interferometer experiments such as eLISA, LISA, BBO and DECIGO.

  7. The gravitational wave spectrum from cosmological B-L breaking

    Energy Technology Data Exchange (ETDEWEB)

    Buchmueller, W.; Domcke, V.; Kamada, K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Schmitz, K. [Tokyo Univ., Kashiwa (Japan). Kavli IPMU (WPI)

    2013-05-15

    Cosmological B-L breaking is a natural and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase drives hybrid inflation, ending in tachyonic preheating. The decays of heavy B-L Higgs bosons and heavy neutrinos generate entropy, baryon asymmetry and dark matter and also control the reheating temperature. The different phases in the transition from inflation to the radiation dominated phase produce a characteristic spectrum of gravitational waves. We calculate the complete gravitational wave spectrum due to inflation, preheating and cosmic strings, which turns out to have several features. The production of gravitational waves from cosmic strings has large uncertainties, with lower and upper bounds provided by Abelian Higgs strings and Nambu-Goto strings, implying {Omega}{sub GW}h{sup 2}{proportional_to}10{sup -13}-10{sup -8}, much larger than the spectral amplitude predicted by inflation. Forthcoming gravitational wave detectors such as eLISA, advanced LIGO and BBO/DECIGO will reach the sensitivity needed to test the predictions from cosmological B-L breaking.

  8. The gravitational wave spectrum from cosmological B-L breaking

    Energy Technology Data Exchange (ETDEWEB)

    Buchmüller, W.; Domcke, V.; Kamada, K. [Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg (Germany); Schmitz, K., E-mail: buchmuwi@mail.desy.de, E-mail: valerie.domcke@desy.de, E-mail: kohei.kamada@desy.de, E-mail: kai.schmitz@ipmu.jp [Kavli IPMU (WPI), University of Tokyo, Kashiwa 277-8583 (Japan)

    2013-10-01

    Cosmological B-L breaking is a natural and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase drives hybrid inflation, ending in tachyonic preheating. The decays of heavy B-L Higgs bosons and heavy neutrinos generate entropy, baryon asymmetry and dark matter and also control the reheating temperature. The different phases in the transition from inflation to the radiation dominated phase produce a characteristic spectrum of gravitational waves. We calculate the complete gravitational wave spectrum due to inflation, preheating and cosmic strings, which turns out to have several features. The production of gravitational waves from cosmic strings has large uncertainties, with lower and upper bounds provided by Abelian Higgs strings and Nambu-Goto strings, implying Ω{sub GW}h{sup 2} ∼ 10{sup −13}–10{sup −8}, much larger than the spectral amplitude predicted by inflation. Forthcoming gravitational wave detectors such as eLISA, advanced LIGO, ET, BBO and DECIGO will reach the sensitivity needed to test the predictions from cosmological B-L breaking.

  9. Centronotus fasciatus Bl. & Schn. aan de Nederlandsche kust

    NARCIS (Netherlands)

    Popta, C.M.L.

    1916-01-01

    In de collectie van het Leidsche Museum bevindt zich een Centronotus fasciatus Bl. & Sch., volgens de opgave op het etiket afkomstig van de Hollandsche kust. De kenmerken van dit individu, dat 230 mm. lang is, zijn: De hoogte van het langwerpige lichaam gaat 9 7/12 en de lengte van den, evenals het

  10. LacR mutations are frequently observed in Streptococcus intermedius and are responsible for increased intermedilysin production and virulence.

    Science.gov (United States)

    Tomoyasu, Toshifumi; Imaki, Hidenori; Masuda, Sachiko; Okamoto, Ayumi; Kim, Hyejin; Waite, Richard D; Whiley, Robert A; Kikuchi, Ken; Hiramatsu, Keiichi; Tabata, Atsushi; Nagamune, Hideaki

    2013-09-01

    Streptococcus intermedius secretes a human-specific cytolysin, intermedilysin (ILY), which is considered to be the major virulence factor of this pathogen. We screened for a repressor of ily expression by using random gene disruption in a low-ILY-producing strain (PC574). Three independent high-ILY-producing colonies that had plasmid insertions within a gene that has high homology to lacR were isolated. Validation of these observations was achieved through disruption of lacR in strain PC574 with an erythromycin cassette, which also led to higher hemolytic activity, increased transcription of ily, and higher cytotoxicity against HepG2 cells, compared to the parental strain. The direct binding of LacR within the ily promoter region was shown by a biotinylated DNA probe pulldown assay, and the amount of ILY secreted into the culture supernatant by PC574 cells was increased by adding lactose or galactose to the medium as a carbon source. Furthermore, we examined lacR nucleotide sequences and the hemolytic activity of 50 strains isolated from clinical infections and 7 strains isolated from dental plaque. Of the 50 strains isolated from infections, 13 showed high ILY production, 11 of these 13 strains had one or more point mutations and/or an insertion mutation in LacR, and almost all mutations were associated with a marked decline in LacR function. These results strongly suggest that mutation in lacR is required for the overproduction of ILY, which is associated with an increase in pathogenicity of S. intermedius.

  11. Complete genome sequence of the probiotic Lactobacillus casei strain BL23.

    NARCIS (Netherlands)

    Maze, A.; Boel, G.; Zuniga, M.; Bourand, A.; Loux, V.; Yebra, M.J.; Monedero, V.; Correia, K.; Jacques, N.; Beaufils, S.; Poncet, S.; Joyet, P.; Milohanic, E.; Casaregola, S.; Auffray, Y.; Perez-Martinez, G.; Gibrat, J.F.; Zagorec, M.; Francke, C.; Hartke, A.; Deutscher, J.

    2010-01-01

    The entire genome of Lactobacillus casei BL23, a strain with probiotic properties, has been sequenced. The genomes of BL23 and the industrially used probiotic strain Shirota YIT 9029 (Yakult) seem to be very similar.

  12. Geology and ground-water resources of Fond du Lac County, Wisconsin

    Science.gov (United States)

    Newport, Thomas G.

    1962-01-01

    The principal water-bearing rocks underlying Fond du Lac County, Wis., are sandstones of Cambrian and Ordovician age and dolomite of Silurian age. Other aquifers include dolomite of Ordovician age and sand. and gravel of Quaternary age. Crystalline rocks of Precambrian age, which underlie all the water-bearing formations, form a practically impermeable basement complex and yield little or no water to wells. Ground water is the source of all public and most private and industrial water supplies in the county. The municipalities and industries obtain water chiefly from wells that penetrate the sandstones of Cambrian and Ordorician age. The Platteville formation and Galena dolomite of Ordovician age and the Niagara dolomite of Silurian age supply water to most domestic and stock wells and to a few industrial wells. Several buried valleys in the bedrock surface contain water-bearing deposits of sand and gravel. The source of the ground water in Fond du Lac County is local precipitation. Recharge to the water-bearing beds occurs in most of the county but is greatest where the bedrock formations are near the surface. Ground water is discharged by seeps and springs, by evaporation and transpiration, and by wells. Ground-water levels in wells fluctuate in response to recharge and to natural discharge and pumping. In areas not affected by pumping, water levels generally decline through the summer months because of natural discharge and lack of recharge, recover slightly in the fall after the first killing frost, decline during the winter, and recover in the spring when recharge is greatest. In areas of heavy pumping, the water levels are lowest in late summer and highest in late winter. Water levels in wells in the Fond du Lac area were about 5 to 50 feet above the land surface in 1885, but they had declined to as low as 185 feet below the land surface by 1957. Coefficients of transmissibility and storage of the sandstones of Cambrian and Ordovician age were determined by

  13. 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

  14. 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.

  15. 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.

  16. 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

  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. In vivo role of the relA+ gene in regulation of the lac operon.

    OpenAIRE

    Primakoff, P

    1981-01-01

    Under conditions of amino acid limitation, beta-galactosidase was produced at a 70-fold higher rate in a relA+ strain than in an isogenic relA strain of Escherichia coli K-12. Under identical conditions with the relA+ and relA strains carrying various lac promoter mutations, rates of beta-galactosidase synthesis in relA+ (relative to relA) ranged from 26-fold higher (promoter mutant Pr 13) to only 5-fold higher (promoter mutant PrL8uv5). This promoter specificity was independent of strain bac...

  19. Galactic membership of BL Her type variable stars

    CERN Document Server

    Jurkovic, Monika I; Ninković, Slobodan

    2016-01-01

    As the RR Lyrae stars evolve on the Hertzsprung-Russell diagram they are believed to become short period Type II Cepheids, known as BL Her type (with a pulsation period from $1$ to $3-8$ days). Assuming that their mass is around $0.5 - 0.6 {\\rm M}_{\\odot}$, and that they are low metallicity objects, they were thought to belong to the halo of the Milky Way. We investigated seven Galactic short period Type II Cepheids (BL Her, SW Tau, V553 Cen, DQ And, BD Cas, V383 Cyg, and KT Com) in order to establish their membership within the Galactic structure using the kinematic approach. $Gaia$ should provide us with more data needed to conduct the study of the whole sample.

  20. Galactic membership of BL Her type variable stars

    Science.gov (United States)

    Jurkovic, M. I.; Stojanovic, M.; Ninkovic, S.

    2016-05-01

    As the RR Lyrae stars evolve on the Hertzsprung-Russell diagram they are believed to become short period Type II Cepheids, known as BL Her type (with a pulsation period from 1 to 3-8 days). Assuming that their mass is around 0.5-0.6M_Sol, and that they are low metallicity objects, they were thought to belong to the halo of the Milky Way. We investigated seven Galactic short period Type II Cepheids (BL Her, SW Tau, V553 Cen, DQ And, BD Cas, V383 Cyg, and KT Com) in order to establish their membership within the Galactic structure using the kinematic approach. Gaia should provide us with more data needed to conduct the study of the whole sample.

  1. Period doubling and Blazhko modulation in BL Herculis hydrodynamic models

    CERN Document Server

    Smolec, R

    2012-01-01

    We present the hydrodynamic BL Herculis-type models which display a long-term modulation of pulsation amplitudes and phases. The modulation is either strictly periodic or it is quasi-periodic, with the modulation period and modulation pattern varying from one cycle to the other. Such behaviour has not been observed in any BL Her variable so far, however, it is a common property of their lower luminosity siblings - RR Lyrae variables showing the Blazhko effect. These models provide a support for the recent mechanism proposed by Buchler & Kollath to explain this still mysterious phenomenon. In their model, a half-integer resonance that causes the period doubling effect, discovered recently in the Blazhko RR Lyrae stars, is responsible for the modulation of the pulsation as well. Although our models are more luminous than is appropriate for RR Lyrae stars, they clearly demonstrate, through direct hydrodynamic computation, that the mechanism can indeed be operational. Of great importance are models which show...

  2. Variability Study of the SX Phoenicis Star BL Camelopardalis

    Institute of Scientific and Technical Information of China (English)

    Jian-Ning Fu; Chao Zhang; Kanokwan Marak; Chayan Boonyarak; Pongsak Khokhuntod; Shi-Yang Jiang

    2008-01-01

    New time-series photometric observations of BL Cam in the V band and white light were made during 2005 to 2007 at the Xinglong Station of China. The frequency analysis confirms two closely separated frequencies, 25.181 d-1 and 25.571 d-1, but the frequency of 31-32 d-1 reported in the literature was not detected in the new data. New times of maximum light were determined from both our light curves and those available on Internet, allowing a more comprehensive study of the O - C diagram, together with the times of maximum light in the literature. A new interpretation, including the period increasing before 1988 and decreasing since 1992 of BL Cam and the light-time effect in a binary system, looks plausible.

  3. Asymmetric Gepner Models III. B-L Lifting

    CERN Document Server

    Gato-Rivera, B

    2010-01-01

    In the same spirit as heterotic weight lifting, B-L lifting is a way of replacing the superfluous and ubiquitous U(1)_{B-L} with something else with the same modular properties, but different conformal weights and ground state dimensions. This method works in principle for all variants of (2,2) constructions, such as orbifolds, Calabi-Yau manifolds, free bosons and fermions and Gepner models, since it only modifies the universal SO(10) x E_8 part of the CFT. However, it can only yield chiral spectra if the ``internal" sector of the theory provides a simple current of order 5. Here we apply this new method to Gepner models. Including exceptional invariants, 86 of them have the required order 5 simple current, and 69 of these yield chiral spectra. Three family spectra occur abundantly.

  4. Asymmetric Gepner models III. B-L lifting

    Energy Technology Data Exchange (ETDEWEB)

    Gato-Rivera, B. [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); Schellekens, A.N., E-mail: t58@nikhef.n [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); IMAPP, Radboud Universiteit, Nijmegen (Netherlands)

    2011-06-21

    In the same spirit as heterotic weight lifting, B-L lifting is a way of replacing the superfluous and ubiquitous U(1){sub B-L} with something else with the same modular properties, but different conformal weights and ground state dimensions. This method works in principle for all variants of (2,2) constructions, such as orbifolds, Calabi-Yau manifolds, free bosons and fermions and Gepner models, since it only modifies the universal SO(10)xE{sub 8} part of the CFT. However, it can only yield chiral spectra if the 'internal' sector of the theory provides a simple current of order 5. Here we apply this new method to Gepner models. Including exceptional invariants, 86 of them have the required order 5 simple current, and 69 of these yield chiral spectra. Three family spectra occur abundantly.

  5. Long-term optical and radio variability of BL Lacertae

    Science.gov (United States)

    Guo, Y. C.; Hu, S. M.; Xu, C.; Liu, C. Y.; Chen, X.; Guo, D. F.; Meng, F. Y.; Xu, M. T.; Xu, J. Q.

    2015-04-01

    Well-sampled optical and radio light curves of BL Lacertae in B, V, R, I bands and 4.8, 8.0, 14.5 GHz from 1968 to 2014 were presented in this paper. A possible 1.26 ± 0.05 yr period in optical bands and a 7.50 ± 0.15 yr period in radio bands were detected based on discrete correlation function, structure function as well as Jurkevich method. Correlations among different bands were also analyzed and no reliable time delay was found between optical bands. Very weak correlations were detected between V band and radio bands. However, in radio bands the variation at low frequency lagged that at high frequency obviously. The spectrum of BL Lacertae turned mildly bluer when the object turned brighter, and stronger bluer-when-brighter trends were found for short flares. A scenario including a precessing helical jet and periodic shocks was put forward to interpret the variation characteristics of BL Lacertae.

  6. The Gravitational Wave Spectrum from Cosmological B-L Breaking

    CERN Document Server

    Buchmuller, Wilfried; Kamada, Kohei; Schmitz, Kai

    2013-01-01

    Cosmological B-L breaking is a natural and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase drives hybrid inflation, ending in tachyonic preheating. The decays of heavy B-L Higgs bosons and heavy neutrinos generate entropy, baryon asymmetry and dark matter and also control the reheating temperature. The different phases in the transition from inflation to the radiation dominated phase produce a characteristic spectrum of gravitational waves. We calculate the complete gravitational wave spectrum due to inflation, preheating and cosmic strings, which turns out to have several features. The production of gravitational waves from cosmic strings has large uncertainties, with lower and upper bounds provided by Abelian Higgs strings and Nambu-Goto strings, implying \\Omega_GW h^2 ~ 10^{-13} - 10^{-8}, much larger than the spectral amplitude predicted by inflation. Forthcoming gravitational wave detectors such as eL...

  7. 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.

  8. Northern hemisphere mid-latitude geomagnetic anomaly revealed from Levantine Archaeomagnetic Compilation (LAC).

    Science.gov (United States)

    Shaar, R.; Tauxe, L.; Agnon, A.; Ben-Yosef, E.; Hassul, E.

    2015-12-01

    The rich archaeological heritage of Israel and nearby Levantine countries provides a unique opportunity for archaeomagnetic investigation in high resolution. Here we present a summary of our ongoing effort to reconstruct geomagnetic variations of the past several millennia in the Levant at decadal to millennial resolution. This effort at the Southern Levant, namely the "Levantine Archaeomagnetic Compilation" (LAC), presently consists of data from over 650 well-dated archaeological objects including pottery, slag, ovens, and furnaces. In this talk we review the methodological challenges in achieving a robust master secular variation curve with realistic error estimations from a large number of different datasets. We present the current status of the compilation, including the southern and western Levant LAC data (Israel, Cyprus, and Jordan) and other published north-eastern Levant data (Syria and southern Turkey), and outline the main findings emerging from these data. The main feature apparent from the new compilation is an extraordinary intensity high that developed over the Levant region during the first two millennia BCE. The climax of this event is a double peak intensity maximum starting at ca. 1000 BCE and ending at ca. 735 BCE, accompanied with at least two events of geomagnetic spikes. Paleomagnetic directions from this period demonstrate anomalies of up to 20 degrees far from the averaged GAD field. This leads us to postulate that the maximum in the intensity is a manifestation of an intense mid-latitude local positive geomagnetic anomaly that persisted for over two centuries.

  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. 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.

  11. 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.

  12. Large Inversion in Escherichia Coli K-12 1485in between Inversely Oriented Is3 Elements near Lac and Cdd

    OpenAIRE

    Komoda, Y.; Enomoto, M.; Tominaga, A

    1991-01-01

    A companion study has shown that the inversion carried by strain 1485IN has one terminus between lac and proC and the other between his and cdd of the normal strain. Starting with this mapping data, we have done molecular work demonstrating that the inversion occurred by recombination between inversely oriented two IS3 elements, one present near lac and the other near the cdd locus; i.e., the inversion is IN(is3B-is3E). Evidence supporting this conclusion includes: (i) Normal and inversion st...

  13. 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

  14. Discovery and characterization of the first low-peaked and intermediate-peaked BL Lacertae objects in the very high energy {gamma}-ray regime

    Energy Technology Data Exchange (ETDEWEB)

    Berger, Karsten

    2009-12-19

    20 years after the discovery of the Crab Nebula as a source of very high energy {gamma}-rays, the number of sources newly discovered above 100 GeV using ground-based Cherenkov telescopes has considerably grown, at the time of writing of this thesis to a total of 81. The sources are of different types, including galactic sources such as supernova remnants, pulsars, binary systems, or so-far unidentified accelerators and extragalactic sources such as blazars and radio galaxies. The goal of this thesis work was to search for {gamma}-ray emission from a particular type of blazars previously undetected at very high {gamma}-ray energies, by using the MAGIC telescope. Those blazars previously detected were all of the same type, the so-called high-peaked BL Lacertae objects. The sources emit purely non-thermal emission, and exhibit a peak in their radio-to-X-ray spectral energy distribution at X-ray energies. The entire blazar population extends from these rare, low-luminosity BL Lacertae objects with peaks at X-ray energies to the much more numerous, high-luminosity infrared-peaked radio quasars. Indeed, the low-peaked sources dominate the source counts obtained from space-borne observations at {gamma}-ray energies up to 10 GeV. Their spectra observed at lower {gamma}-ray energies show power-law extensions to higher energies, although theoretical models suggest them to turn over at energies below 100 GeV. This opened the quest for MAGIC as the Cherenkov telescope with the currently lowest energy threshold. In the framework of this thesis, the search was focused on the prominent sources BL Lac, W Comae and S5 0716+714, respectively. Two of the sources were unambiguously discovered at very high energy {gamma}-rays with the MAGIC telescope, based on the analysis of a total of about 150 hours worth of data collected between 2005 and 2008. The analysis of this very large data set required novel techniques for treating the effects of twilight conditions on the data quality

  15. Discovery and characterization of the first low-peaked and intermediate-peaked BL Lacertae objects in the very high energy γ-ray regime

    International Nuclear Information System (INIS)

    20 years after the discovery of the Crab Nebula as a source of very high energy γ-rays, the number of sources newly discovered above 100 GeV using ground-based Cherenkov telescopes has considerably grown, at the time of writing of this thesis to a total of 81. The sources are of different types, including galactic sources such as supernova remnants, pulsars, binary systems, or so-far unidentified accelerators and extragalactic sources such as blazars and radio galaxies. The goal of this thesis work was to search for γ-ray emission from a particular type of blazars previously undetected at very high γ-ray energies, by using the MAGIC telescope. Those blazars previously detected were all of the same type, the so-called high-peaked BL Lacertae objects. The sources emit purely non-thermal emission, and exhibit a peak in their radio-to-X-ray spectral energy distribution at X-ray energies. The entire blazar population extends from these rare, low-luminosity BL Lacertae objects with peaks at X-ray energies to the much more numerous, high-luminosity infrared-peaked radio quasars. Indeed, the low-peaked sources dominate the source counts obtained from space-borne observations at γ-ray energies up to 10 GeV. Their spectra observed at lower γ-ray energies show power-law extensions to higher energies, although theoretical models suggest them to turn over at energies below 100 GeV. This opened the quest for MAGIC as the Cherenkov telescope with the currently lowest energy threshold. In the framework of this thesis, the search was focused on the prominent sources BL Lac, W Comae and S5 0716+714, respectively. Two of the sources were unambiguously discovered at very high energy γ-rays with the MAGIC telescope, based on the analysis of a total of about 150 hours worth of data collected between 2005 and 2008. The analysis of this very large data set required novel techniques for treating the effects of twilight conditions on the data quality. This was successfully achieved

  16. Variabilidade óptica de longo período e precessão de jato: o caso de BL Lacertae

    Science.gov (United States)

    Caproni, A.; Abraham, Z.

    2003-08-01

    Variabilidade é tipicamente uma característica de AGNs, sendo observada em toda a faixa eletromagnética. Em relação às escalas de tempo, variações desde horas até de algumas décadas foram encontradas por vários autores. Em alguns casos, análises temporais de curvas de luz mostram a existência de periodicidade nas variações observadas. Um exemplo de objeto que preenche as características mencionadas acima é BL Lacertae, o protótipo da classe BL Lac dos AGNs. Neste trabalho, nós interpretamos a variabilidade periódica de longo período detectada na curva de luz na banda B (~7,5 anos) como o resultado da periodicidade na amplificação da radiação oriunda do jato relativístico. Neste cenário, a amplificação periódica seria induzida pela precessão, que muda o ângulo entre o jato e a linha de visada. Com esta abordagem e vínculos adicionais fornecidos por observações em altas energias, nós podemos impor limites para os parâmetros do modelo de precessão, tais como o fator de Lorentz associado ao movimento global do jato, o ângulo de abertura do cone de precessão e o ângulo entre o eixo do cone e a linha de visada.

  17. Effet des conditions climatiques sur le niveau du lac Sidi Ali (Moyen Atlas, Maroc

    Directory of Open Access Journals (Sweden)

    Claude Martin

    2011-11-01

    Full Text Available Le lac Sidi Ali est un lac naturel d'altitude (2070-2080 m, sans exutoire superficiel, déterminé par le barrage d'une coulée basaltique. Doté d'un bassin versant apparent de 15,6 km2, il est alimenté par des eaux de ruissellement et par des sources karstiques. Son niveau subit des variations très fortes, annuelles et interannuelles, sous le contrôle des conditions climatiques, et en particulier des pluies et de l'évapotranspiration. Les périodes de sécheresse qui ont marqué les trois dernières décennies, se sont traduites par un abaissement du niveau de près de 7 m. Mais les précipitations abondantes des années 2008-09 et 2009-10 ont provoqué une nette remontée. Une régression multiple d'assez bonne qualité (r = 0,87 lie la variation annuelle du niveau (d'août à août à différents paramètres (conditions climatiques et niveau initial du lac.Lake Sidi Ali is a natural lake at high altitude (2070-2080 m, without surface outlet, determined by the dam of a basalt flow. With an apparent catchment of 15.6 km2, it is fed by runoff and karst springs. Its level shows strong annual and interannual variations, depending on weather conditions, particularly rainfall and evapotranspiration. Droughts that have marked the last three decades have resulted in a lowering of about 7 m of the water level. But heavy rainfall that occurred in 2008-09 and 2009-10 caused a marked rise. A multiple regression of sufficient quality (r = 0.87 binds the annual change (from august to august at differents parameters (weather conditions and initial level of the lake.

  18. 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

    ) according to the dating method employed (archaeological, historical, radiocarbon). In addition, we cross check results from multiple archaeological sites using different source materials dated using different methodologies. The results of this effort are summarized in a regional compilation namely Levantine Archaeomagnetic Curve - LAC. The initial version of the LAC includes recently published data from ancient copper production sites, and new data from two important biblical archaeological mounds in Israel - Tel Megiddo ("Armageddon") and Tel Hazor. In this talk we review our working methodologies, report the current status of the LAC, and discuss its implications on our understanding of geomagnetic secular variations.

  19. Functional Analysis of the Lactobacillus casei BL23 Sortases

    Science.gov (United States)

    Muñoz-Provencio, Diego; Rodríguez-Díaz, Jesús; Collado, María Carmen; Langella, Philippe; Bermúdez-Humarán, Luis G.

    2012-01-01

    Sortases are a class of enzymes that anchor surface proteins to the cell wall of Gram-positive bacteria. Lactobacillus casei BL23 harbors four sortase genes, two belonging to class A (srtA1 and srtA2) and two belonging to class C (srtC1 and srtC2). Class C sortases were clustered with genes encoding their putative substrates that were homologous to the SpaEFG and SpaCBA proteins that encode mucus adhesive pili in Lactobacillus rhamnosus GG. Twenty-three genes encoding putative sortase substrates were identified in the L. casei BL23 genome with unknown (35%), enzymatic (30%), or adhesion-related (35%) functions. Strains disrupted in srtA1, srtA2, srtC1, and srtC2 and an srtA1 srtA2 double mutant were constructed. The transcription of all four sortase encoding genes was detected, but only the mutation of srtA1 resulted in a decrease in bacterial surface hydrophobicity. The β-N-acetyl-glucosaminidase and cell wall proteinase activities of whole cells diminished in the srtA1 mutant and, to a greater extent, in the srtA1 srtA2 double mutant. Cell wall anchoring of the staphylococcal NucA reporter protein fused to a cell wall sorting sequence was also affected in the srtA mutants, and the percentages of adhesion to Caco-2 and HT-29 intestinal epithelial cells were reduced for the srtA1 srtA2 strain. Mutations in srtC1 or srtC2 result in an undetectable phenotype. Together, these results suggest that SrtA1 is the housekeeping sortase in L. casei BL23 and SrtA2 would carry out redundant or complementary functions that become evident when SrtA1 activity is absent. PMID:23042174

  20. Another look at the BL Lacertae flux and spectral variability

    OpenAIRE

    Raiteri, C. M.; Villata, M.; BRUSCHINI, L.; Capetti, A.; Kurtanidze, O. M.; Larionov, V. M.; Romano, P; Vercellone, S.; Agudo, I.; Aller, H. D.; Aller, M. F.; Arkharov, A. A.; Bach, U.; Berdyugin, A.; Blinov, D. A.

    2010-01-01

    The GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) monitored BL Lacertae in 2008-2009 at radio, near-IR, and optical frequencies. During this period, high-energy observations were performed by XMM-Newton, Swift, and Fermi. We analyse these data with particular attention to the calibration of Swift UV data, and apply a helical jet model to interpret the source broad-band variability. The GASP-WEBT observations show an optical flare in 2008 February-March, and osc...

  1. BeppoSAX observations of 1 Jy BL Lacertae objects

    International Nuclear Information System (INIS)

    Preliminary results on BeppoSAX LECS and MECS observations of BL Lacertae objects selected from the 1 Jy sample are presented. All sources of the LBL type, that is, characterized by a peak in their multifrequency spectra at infrared/optical energies, seem to show a relatively flat (αx ∼ 0.7 - 0.8) X-ray spectrum. This is in agreement with the supposed dominance of inverse Compton emission in the X-ray band of these sources

  2. 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

  3. 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.

  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. 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

  6. 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.

  7. 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

  8. Analysis of in-vivo LacR-mediated gene repression based on the mechanics of DNA looping.

    Directory of Open Access Journals (Sweden)

    Yongli Zhang

    Full Text Available Interactions of E. coli lac repressor (LacR with a pair of operator sites on the same DNA molecule can lead to the formation of looped nucleoprotein complexes both in vitro and in vivo. As a major paradigm for loop-mediated gene regulation, parameters such as operator affinity and spacing, repressor concentration, and DNA bending induced by specific or non-specific DNA-binding proteins (e.g., HU, have been examined extensively. However, a complete and rigorous model that integrates all of these aspects in a systematic and quantitative treatment of experimental data has not been available. Applying our recent statistical-mechanical theory for DNA looping, we calculated repression as a function of operator spacing (58-156 bp from first principles and obtained excellent agreement with independent sets of in-vivo data. The results suggest that a linear extended, as opposed to a closed v-shaped, LacR conformation is the dominant form of the tetramer in vivo. Moreover, loop-mediated repression in wild-type E. coli strains is facilitated by decreased DNA rigidity and high levels of flexibility in the LacR tetramer. In contrast, repression data for strains lacking HU gave a near-normal value of the DNA persistence length. These findings underscore the importance of both protein conformation and elasticity in the formation of small DNA loops widely observed in vivo, and demonstrate the utility of quantitatively analyzing gene regulation based on the mechanics of nucleoprotein complexes.

  9. An observation of GS 2000+25 with the LAC on board the 'GINGA' satellite

    International Nuclear Information System (INIS)

    The X-ray transient GS 2000+25 first appeared in Vulpecula on April 23, 1988. We report observations of this source with the Large Area Counter (LAC) on board the GINGA satellite. These observations were performed between April 30 and May 9, 1988 and on June 1, June 26 and September 8, 1988. The X-ray spectrum has an ultrasoft component and a hard tail. While the ultrasoft component has gradually decayed, the hard component has sometimes increased its intensity independently of the ultrasoft component. Furthermore. the hard component showed the large intensity variation on time scales of 1-100 sec, while the ultrasoft component was relatively stable on those time scales. (author)

  10. Gene fusions with lacZ by duplication insertion in the radioresistant bacterium Deinococcus radiodurans

    International Nuclear Information System (INIS)

    Deinococcus radiodurans is the most-studied species of a eubacterial family characterized by extreme resistance to DNA damage. We have focused on developing molecular biological techniques to investigate the genetics of this organism. We report construction of lacZ gene fusions by a method involving both in vitro splicing and the natural transformation of D. radiodurans. Numerous fusion strains were identified by expression of beta-galactosidase. Among these fusion strains, several were inducible by exposure to the DNA-damaging agent mitomycin C, and four of the inducible fusion constructs were cloned in Escherichia coli. Hybridization studies indicate that one of the damage-inducible genes contains a sequence reiterated throughout the D. radiodurans chromosome. Survival measurements show that two of the fusion strains have increased sensitivity to mitomycin C, suggesting that the fusions within these strains inactivate repair functions

  11. Henein Nessim, Pêche et chasse au lac Manzala, Le Caire, IFAO, 2010, 486 p.

    Directory of Open Access Journals (Sweden)

    Sylvaine Camelin

    2012-07-01

    Full Text Available Le livre Pêche et chasse au lac Manzala de Nessim Heneim présente la particularité d'être un ouvrage hybride : mi-livre photographique dont les images sont si belles qu'elles trouveraient leur place dans une publication d'art, mi-livre technique qui liste les différentes techniques de pêche et dont les descriptions sont si complètes que l'on devine sans peine l'ambition d'exhaustivité de l'auteur. De très belle facture, sa dimension de 20 par 27,5 cm permet de fait une exceptionnelle mise en ...

  12. 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.

  13. The jet of the BL Lacertae object PKS 2201+044: MAD near-IR adaptive optics observations and comparison with optical, radio and X-ray data

    Science.gov (United States)

    Liuzzo, E.; Falomo, R.; Treves, A.; Donato, D.; Sambruna, M.; Arcidiacono, C.; Giovannini, G.; Farinato, J.; Moretti, A.; Ragazzoni, R.; Diolaiti, E.; Lombini, M.; Brast, R.; Donaldson, R.; Kolb, J.; Marchetti, E.; Tordo, S.

    2011-04-01

    Context. Relativistic jets are a common feature of radio loud active galactic nuclei. Multifrequency observations are a unique tool to constrain their physics. Aims: We report on a detailed study of the properties of the jet of the nearby BL Lac object PKS 2201+044, one of the rare cases where the jet is detected from radio to X-rays. Methods: We use new adaptive optics near-IR observations of the source, obtained with the ESO multi-conjugated adaptive optics demonstrator (MAD) at the Very Large Telescope. These observations acquired in Ground-Layer Adaptive Optics mode are combined with images previously achieved by HST, VLA and Chandra to perform a morphological and photometric study of the jet. Results: We find a noticeable similarity in the morphology of the jet at radio, near-IR and optical wavelengths. We construct the spectral shape of the main knot of jet that appears dominated by synchrotron radiation. Conclusions: On the basis of the jet morphology and the weak lines spectrum we suggest that PKS 2201+044 belongs to the class of radio sources intermediate between FRIs and FRIIs.

  14. Ortsgedächtnis für Blütenpositionen bei der Blütenfledermaus Glossophaga soricina

    OpenAIRE

    Stich, Kai Petra

    2004-01-01

    Die Nahrungssuche ist für Tiere kein triviales Verhaltensproblem. Nahrung ist im Habitat eines Tieres selten homogen verteilt, wobei räumliche Heterogenität unter anderem durch das zeitliche Muster der Ressourcenerneuerung und durch die Nahrungssuche der Tiere selbst verursacht wird. Besonders bei sich rasch erneuernden Nahrungsquellen wie z.B. Blütennektar ist es für viele Tiere von Vorteil, sich einerseits den Ort dieser Quellen zu merken, um wieder dorthin zurückzukehren, andererseits jedo...

  15. 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

  16. Resumen de tesis. La B(1,3)glucán sintasa Bgs1 es esencial en el control de la polaridad celular y la citocinesis de Schizosaccharomyces pombe

    OpenAIRE

    Ramos Vecino, Mariona

    2014-01-01

    [ES]El complejo enzimático de la beta(1,3)glucán sintasa de la levadura de fisión Schizosaccharomyces pombe está compuesta por una subunidad catalítica codificada por los genes de la familia Bgs. Bgs1 es esencial y es responsable de la síntesis del beta(1,3)glucano lineal que da lugar a la estructura del septo primario de división. En ausencia de Bgs1 las células presentan defectos en separación celular y en la selección del sitio de crecimiento polarizado. En este trabajo de tesis se pon...

  17. Defective insulin secretory response to intravenous glucose in C57Bl/6J compared to C57Bl/6N mice

    Directory of Open Access Journals (Sweden)

    Grace Fergusson

    2014-12-01

    Conclusions: The Bl/6J mouse strain displays impaired insulin secretion. These results have important implications for choosing the appropriate test to assess beta-cell function and background strain in genetically modified mouse models.

  18. Code validation and scaling of the LOBI BL-30 experiment

    Energy Technology Data Exchange (ETDEWEB)

    Pla, P.; Reventos, F.; Pretel, C. [Catalonia Technical Univ., Barcelona (Spain); Pla, P.; Giannotti, W.; D' Auria, F. [Pisa Univ. (Italy); Annunziato, A. [Joint Research Centre of the European Commission, Ispra (Italy); Sol, I. [Associacio Nuclear Asco-Vandellos 2, L' Hospitalet de l' Infant (Tarragona)(Spain)

    2007-07-01

    Integral test facilities (ITFs) are one of the main tools for the validation of best-estimate thermalhydraulic system codes. The experimental data are also of great value when compared to the experiment scaled-conditions in a full Nuclear Power Plant (NPP). The LOBI-MOD2 was a single plus a triple loop (simulated by one loop) test facility electrically heated to simulate a 1300 MWe Pressurized Water Reactor (PWR). The scaling factor was 712 for the core power, volume and mass flow. Primary and secondary sides contained all the main active elements. It was located and operated at the European Commission Joint Research Centre (JRC) of Ispra, Italy. Experimental data of tests performed at the facility are available on-line through the JRC STRESA web platform for code validation purposes. The paper is focused in the simulation (with RELAP5 Mod-3.3) of the LOBI BL-30 experiment - a 5% small break Loss Of Coolant Accident (SB-LOCA) in the cold leg - the prediction of the general timing of events and primary system and secondary system quantities trends appear to be in good agreement with experimental data. The exercise continued with the simulation (with RELAP5 Mod 3.3) of the scaling of the LOBI BL-30 experiment to the Spanish reactor ASCO-2, a 3-loops 2940.6 MWth Westinghouse PWR. We have obtained good agreement with experimental data and have explained the reason of some discrepancies in the accumulator behaviour. To complete and compare the results, for the same NPP two other calculations have been performed: a non-scaled reference calculation of a 5% SB-LOCA in the cold leg with all the typical NPP safety systems connected and a SB-LOCA calculation with only the break area scaled and all the typical NPP safety systems connected. Both calculations have led to a safe end of the transient.

  19. 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.

  20. Blæksprutter beskyttes på niveau med hvirveldyr

    DEFF Research Database (Denmark)

    Alstrup, Aage Kristian Olsen

    2015-01-01

    beskyttede. Et af de bedst studerede hvirvelløse dyr er blæksprutten, navnlig Octopus vulgaris. Vores viden om nerveimpulsen udbredelse stammer netop fra blæksprutter, da de har meget store nerveceller, der let lader sig undersøge. De to forskere fik faktisk Nobelprisen i 1963 for opdagelsen. Siden da har...

  1. $Z^\\prime_{BL}$ portal dark matter and LHC Run-2 results

    CERN Document Server

    Okada, Nobuchika

    2016-01-01

    We consider a concise dark matter scenario in the minimal gauged $B-L$ extension of the Standard Model (SM), where the global $B-L$ (baryon number minus lepton number) symmetry in the SM is gauged, and three generations of right-handed neutrinos and a $B-L$ Higgs field are introduced. Associated with the $B-L$ gauge symmetry breaking by a VEV of the $B-L$ Higgs field, the seesaw mechanism for generating the neutrino mass is automatically implemented after the electroweak symmetry breaking in the SM. In this model context, we introduce a $Z_2$-parity and assign an odd parity for one right-handed neutrino while even parities for the other fields. Therefore, the dark matter candidate is identified as the right-handed Majorana neutrino with odd $Z_2$ parity, keeping the minimality of the particle content intact. When the dark matter particle communicates with the SM particles mainly through the $B-L$ gauge boson ($Z^\\prime_{BL}$ boson), its relic abundance is determined by only three free parameters, the $B-L$ ga...

  2. 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...

  3. Narrative report May, June, July, August, 1954 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 1954. The report begins by summarizing the...

  4. 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...

  5. Narrative report May, June, July, August, 1956 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo 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 1956. The report begins by summarizing the...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. Narrative report September, October, November, December, 1951 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge & Easement Refuges - District IV and 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 1951. The report begins by...

  15. 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...

  16. 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...

  17. Narrative report January, February, March, April, 1953 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, & Easement Refuges - District IV and 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 1953. The report begins by summarizing the...

  18. Narrative report January, February, March, April, 1952 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 1952. The report begins by summarizing the...

  19. Narrative report January, February, March, April, 1951 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 1951. The report begins by summarizing the...

  20. Narrative report January, February, March, April, 1955 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 1955. The report begins by summarizing the...

  1. Narrative report September, October, November, December, 1952 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 1952. The report begins by...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. Narrative report September, October, November, December, 1959 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge, and 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...

  9. Narrative report September, October, November, December, 1960 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge and 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...

  10. Narrative report September, October, November, December, 1956 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 1956. The report begins by...

  11. 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...

  12. 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...

  13. 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...

  14. Narrative report January, February, March, April, 1956 Des Lacs National Wildlife Refuge, Lostwood 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 1956. The report begins by summarizing the...

  15. Narrative report January, February, March, April, 1950 Des Lacs National Wildlife Refuge, Lostwood National Wildlife Refuge, Easement Districts IV and IVA, Lake Ilo 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 1950. The report begins by summarizing the...

  16. Narrative report January, February, March, April, 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, Lostwood National Wildlife Refuge, Lake Ilo National Wildlife Refuge, and Easement Refuges - Districts...

  17. 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...

  18. Narrative report January, February, March, April, 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...

  19. 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...

  20. 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...