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| 2. |
- Ackermann, M., et al.
(author)
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THE THIRD CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE
- 2015
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In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 810:1
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Journal article (peer-reviewed)abstract
- The third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC) is presented. It is based on the third Fermi-LAT catalog (3FGL) of sources detected between 100 MeV and 300 GeV with a Test Statistic greater than 25, between 2008 August 4 and 2012 July 31. The 3LAC includes 1591 AGNs located at high Galactic latitudes (vertical bar b vertical bar > 10 degrees), a 71% increase over the second catalog based on 2 years of data. There are 28 duplicate associations, thus 1563 of the 2192 high-latitude gamma-ray sources of the 3FGL catalog are AGNs. Most of them (98%) are blazars. About half of the newly detected blazars are of unknown type, i.e., they lack spectroscopic information of sufficient quality to determine the strength of their emission lines. Based on their gamma-ray spectral properties, these sources are evenly split between flat-spectrum radio quasars (FSRQs) and BL Lacs. The most abundant detected BL Lacs are of the high-synchrotron-peaked (HSP) type. About 50% of the BL Lacs have no measured redshifts. A few new rare outliers (HSP-FSRQs and high-luminosity HSP BL Lacs) are reported. The general properties of the 3LAC sample confirm previous findings from earlier catalogs. The fraction of 3LAC blazars in the total population of blazars listed in BZCAT remains non-negligible even at the faint ends of the BZCAT-blazar radio, optical, and X-ray flux distributions, which hints that even the faintest known blazars could eventually shine in gamma-rays at LAT-detection levels. The energy-flux distributions of the different blazar populations are in good agreement with extrapolation from earlier catalogs.
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| 3. |
- Ackermann, M., et al.
(author)
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Fermi establishes classical novae as a distinct class of gamma-ray sources
- 2014
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 345:6196, s. 554-558
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Journal article (peer-reviewed)abstract
- A classical nova results from runaway thermonuclear explosions on the surface of a white dwarf that accretes matter from a low-mass main-sequence stellar companion. In 2012 and 2013, three novae were detected in gamma rays and stood in contrast to the first gamma-ray-detected nova V407 Cygni 2010, which belongs to a rare class of symbiotic binary systems. Despite likely differences in the compositions and masses of their white dwarf progenitors, the three classical novae are similarly characterized as soft-spectrum transient gamma-ray sources detected over 2- to 3-week durations. The gamma-ray detections point to unexpected high-energy particle acceleration processes linked to the mass ejection from thermonuclear explosions in an unanticipated class of Galactic gamma-ray sources.
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| 4. |
- Ackermann, M., et al.
(author)
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Inferred Cosmic-Ray Spectrum from Fermi Large Area Telescope gamma-Ray Observations of Earth's Limb
- 2014
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 112:15, s. 151103-
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Journal article (peer-reviewed)abstract
- Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly discovered features may offer a clue to the origin of high-energy CRs. We use the Fermi Large Area Telescope observations of the gamma-ray emission from Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range similar to 90 GeV-6 TeV (derived from a photon energy range 15 GeV-1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68 +/- 0.04 and 2.61 +/- 0.08 above similar to 200 GeV, respectively.
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| 5. |
- Ackermann, M., et al.
(author)
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The spectrum of isotropic diffuse gamma-ray emission between 100 MeV and 820 GeV
- 2015
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In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 799:1, s. 86-
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Journal article (peer-reviewed)abstract
- The gamma-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse gamma-ray background (IGRB). The IGRB comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual Galactic foregrounds that are approximately isotropic. The first IGRB measurement with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) used 10 months of sky-survey data and considered an energy range between 200 MeV and 100 GeV. Improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse Galactic emission (DGE), and a longer data accumulation of 50 months allow for a refinement and extension of the IGRB measurement with the LAT, now covering the energy range from 100 MeV to 820 GeV. The IGRB spectrum shows a significant high-energy cutoff feature and can be well described over nearly four decades in energy by a power law with exponential cutoff having a spectral index of 2.32 +/- 0.02 and a break energy of (279 +/- 52) GeV using our baseline DGE model. The total intensity attributed to the IGRB is (7.2 +/- 0.6) x 10(-6) cm(-2) s(-1) sr(-1) above 100 MeV, with an additional +15%/-30% systematic uncertainty due to the Galactic diffuse foregrounds.
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| 6. |
- Archambault, S., et al.
(author)
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Deep Broadband Observations of the Distant Gamma-Ray Blazar PKS 1424+240
- 2014
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In: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 785:1
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Journal article (peer-reviewed)abstract
- We present deep VERITAS observations of the blazar PKS 1424+240, along with contemporaneous Fermi Large Area Telescope, Swift X-ray Telescope, and Swift UV Optical Telescope data between 2009 February 19 and 2013 June 8. This blazar resides at a redshift of z ≥ 0.6035, displaying a significantly attenuated gamma-ray flux above 100 GeV due to photon absorption via pair-production with the extragalactic background light. We present more than 100 hr of VERITAS observations over three years, a multiwavelength light curve, and the contemporaneous spectral energy distributions. The source shows a higher flux of (2.1 ± 0.3) × 10–7 photons m–2 s–1 above 120 GeV in 2009 and 2011 as compared to the flux measured in 2013, corresponding to (1.02 ± 0.08) × 10–7 photons m–2 s–1 above 120 GeV. The measured differential very high energy (VHE; E ≥ 100 GeV) spectral indices are Γ = 3.8 ± 0.3, 4.3 ± 0.6 and 4.5 ± 0.2 in 2009, 2011, and 2013, respectively. No significant spectral change across the observation epochs is detected. We find no evidence for variability at gamma-ray opacities of greater than τ = 2, where it is postulated that any variability would be small and occur on timescales longer than a year if hadronic cosmic-ray interactions with extragalactic photon fields provide a secondary VHE photon flux. The data cannot rule out such variability due to low statistics.
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| 7. |
- Acero, F., et al.
(author)
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DEVELOPMENT OF THE MODEL OF GALACTIC INTERSTELLAR EMISSION FOR STANDARD POINT-SOURCE ANALYSIS OF FERMI LARGE AREA TELESCOPE DATA
- 2016
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In: Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 223:2
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Journal article (peer-reviewed)abstract
- Most of the celestial. rays detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope originate from the interstellar medium when energetic cosmic rays interact with interstellar nucleons and photons. Conventional point-source and extended-source studies rely on the modeling of this diffuse emission for accurate characterization. Here, we describe the development of the Galactic Interstellar Emission Model (GIEM), which is the standard adopted by the LAT Collaboration and is publicly available. This model is based on a linear combination of maps for interstellar gas column density in Galactocentric annuli and for the inverse-Compton emission produced in the Galaxy. In the GIEM, we also include large-scale structures like Loop. I and the Fermi bubbles. The measured gas emissivity spectra confirm that the cosmic-ray proton density decreases with Galactocentric distance beyond 5 kpc from the Galactic Center. The measurements also suggest a softening of the proton spectrum with Galactocentric distance. We observe that the Fermi bubbles have boundaries with a shape similar to a catenary at latitudes below 20 degrees and we observe an enhanced emission toward their base extending in the north and south Galactic directions and located within similar to 4 degrees of the Galactic Center.
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| 8. |
- Ackermann, M., et al.
(author)
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THE SPECTRUM AND MORPHOLOGY OF THE FERMI BUBBLES
- 2014
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In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 793:1, s. 64-
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Journal article (peer-reviewed)abstract
- The Fermi bubbles are two large structures in the gamma-ray sky extending to 55 degrees above and below the Galactic center. We analyze 50 months of Fermi Large Area Telescope data between 100MeV and 500 GeV above 10 degrees in Galactic latitude to derive the spectrum and morphology of the Fermi bubbles. We thoroughly explore the systematic uncertainties that arise when modeling the Galactic diffuse emission through two separate approaches. The gamma-ray spectrum is well described by either a log parabola or a power law with an exponential cutoff. We exclude a simple power law with more than 7 sigma significance. The power law with an exponential cutoff has an index of 1.9 +/- 0.2 and a cutoff energy of 110 +/- 50 GeV. We find that the gamma-ray luminosity of the bubbles is 4.4(-0.9)(+2.4) x 10(37) erg s(-1). We confirm a significant enhancement of gamma-ray emission in the southeastern part of the bubbles, but we do not find significant evidence for a jet. No significant variation of the spectrum across the bubbles is detected. The width of the boundary of the bubbles is estimated to be 3.4(-2.6)(+3.7) deg. Both inverse Compton (IC) models and hadronic models including IC emission from secondary leptons fit the gamma-ray data well. In the IC scenario, synchrotron emission from the same population of electrons can also explain the WMAP and Planck microwave haze with a magnetic field between 5 and 20 mu G.
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| 9. |
- Ackermann, M., et al.
(author)
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FERMI LAT STACKING ANALYSIS OF SWIFT LOCALIZED GRBs
- 2016
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In: Astrophysical Journal. - : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 822:2
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Journal article (peer-reviewed)abstract
- We perform a comprehensive stacking analysis of data collected by the Fermi. Large Area Telescope (LAT) of gamma-ray bursts (GRBs) localized by the Swift. spacecraft, which were not detected by the LAT but which fell within the instrument's field of view at the time of trigger. We examine a total of 79 GRBs by comparing the observed counts over a range of time intervals to that expected from designated background orbits, as well as by using a joint likelihood technique to model the expected distribution of stacked counts. We find strong evidence for subthreshold emission at MeV to GeV energies using both techniques. This observed excess is detected during intervals that include and exceed the durations typically characterizing the prompt emission observed at keV energies and lasts at least 2700 s after the co-aligned burst trigger. By utilizing a novel cumulative likelihood analysis, we find that although a burst's prompt gamma-ray and afterglow X-ray flux both correlate with the strength of the subthreshold emission, the X-ray afterglow flux measured by Swift's X-ray Telescope at 11 hr post trigger correlates far more significantly. Overall, the extended nature of the subthreshold emission and its connection to the burst's afterglow brightness lend. further support to the external forward shock origin of the late-time emission detected by the LAT. These results suggest that the extended high-energy emission observed by the LAT may be a relatively common feature but remains undetected in a majority of bursts owing. to instrumental threshold effects.
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| 13. |
- Schaal, J., et al.
(author)
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Coumarin-based octopamine phototriggers and their effects on an insect octopamine receptor
- 2012
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In: ChemBioChem. - : Wiley. - 1439-4227 .- 1439-7633. ; 13:10, s. 1458-1464
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Journal article (peer-reviewed)abstract
- We have developed and characterized efficient caged compounds of the neurotransmitter octopamine. For derivatization, we introduced [6-bromo-8-(diethylaminomethyl)-7-hydroxycoumarin-4-yl]methoxycarbonyl (DBHCMOC) and {6-bromo-7-hydroxy-8-[(piperazin-1-yl)methyl]coumarin-4-yl}methoxycarbonyl (PBHCMOC) moieties as novel photo-removable protecting groups. The caged compounds were functionally inactive when applied to heterologously expressed octopamine receptors (AmOctα1R). Upon irradiation with UV–visible or IR light, bioactive octopamine was released and evoked Ca2+ signals in AmOctα1R-expressing cells. The pronounced water solubility of compounds 2–4 in particular holds great promise for these substances as excellent phototriggers of this important neurotransmitter.
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| 14. |
- Sreenivasan, Akshai P., et al.
(author)
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Predicting protein network topology clusters from chemical structure using deep learning
- 2022
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In: Journal of Cheminformatics. - : BioMed Central. - 1758-2946. ; 14:1
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Journal article (peer-reviewed)abstract
- Comparing chemical structures to infer protein targets and functions is a common approach, but basing comparisons on chemical similarity alone can be misleading. Here we present a methodology for predicting target protein clusters using deep neural networks. The model is trained on clusters of compounds based on similarities calculated from combined compound-protein and protein-protein interaction data using a network topology approach. We compare several deep learning architectures including both convolutional and recurrent neural networks. The best performing method, the recurrent neural network architecture MolPMoFiT, achieved an F1 score approaching 0.9 on a held-out test set of 8907 compounds. In addition, in-depth analysis on a set of eleven well-studied chemical compounds with known functions showed that predictions were justifiable for all but one of the chemicals. Four of the compounds, similar in their molecular structure but with dissimilarities in their function, revealed advantages of our method compared to using chemical similarity.
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| 15. |
- Jaen-Luchoro, Daniel, et al.
(author)
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Corynebacterium genitalium sp. nov., nom. rev. and Corynebacterium pseudogenitalium sp. nov., nom. rev., two old species of the genus Corynebacterium described from clinical and environmental samples
- 2023
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In: Research in Microbiology. - : Elsevier BV. - 0923-2508. ; 174:1-2
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Journal article (peer-reviewed)abstract
- Two Corynebacterium species were proposed decades ago, isolated from clinical samples and divided into biovars: "Corynebacterium genitalium" biovars I-V and "Corynebacterium pseudogenitalium" biovars C1 -C6. Several biovars have been re-classified as new species. Nevertheless, biovar I and C5, together with their respective specific epithets "Corynebacterium genitalium" and "Corynebacterium pseudogenitalium", remained not validly published after more than 40 years. Several more strains, temptatively classified as "C. genitalium" biovar I and "Corynebacterium pseudogenitalium" C5, have been isolated from clinical and environmental samples. Both species presented Gram-positive, non-spore forming rod-shaped cells, able to grow aerobically with CO2. Core-genome analysis identified "C. genitalium" to be most closely related to Corynebacterium tuscaniense, Corynebacterium urinipleomorphum, Corynebacterium aquatimens and C appendicis, and Corynebacterium gottingense as the most closely related species to "C. pseudogenitalium". Comprehensive genomic, genotypic, phenotypic analyses, as well as chemotaxonomic, support the proposal for "C. genitalium" and "C. pseudogenitalium" as distinct species within the genus Corynebacterium. The designated type strains of the two species are Furness 392-1T = ATCC 33030T = CCUG 38989T = CCM 9178T = DSM 113155T for C. genitalium sp. nov., nom. rev., and Furness 162-C2T = ATCC 33039T = CCUG 27540T = CCM 9177T = DSM 113154T for C. pseudogenitalium sp. nov., nom. rev. (c) 2022 The Author(s). Published by Elsevier Masson SAS on behalf of Institut Pasteur. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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| 16. |
- Leventon, Julia, et al.
(author)
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Collaboration or fragmentation? Biodiversity management through the common agricultural policy
- 2017
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In: Land Use Policy. - : Elsevier BV. - 0264-8377. ; 64, s. 1-12
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Journal article (peer-reviewed)abstract
- We argue that the current system of agri-environment management in the European Common Agricultural Policy is ineffective at conserving biodiversity in part because it promotes fragmentation instead of collaboration of actors, thus hindering coordinated biodiversity management. Actor fragmentation is reinforced by the Common Agricultural Policy (CAP) in three ways: (1) through targeting individual farmers; (2) by creating confusion around coordination roles for increasing numbers of actors; and (3) by failing to engage with barriers to collaboration among farmers. Our findings draw on empirical evidence collected through multi-stakeholder workshops in Germany and Sweden. Our argument adds a different dimension to accepted explanations for the ineffectiveness of CAP for biodiversity management. Traditionally, explanations have focussed on low levels of farmer uptake of relevant measures, or the lack of ecological knowledge informing such measures. The level of actor fragmentation identified here suggests that a fundamental rethink of farmland biodiversity management is needed. We propose a new research agenda to identify more effective governance approaches.
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| 19. |
- Lundström, Johan N., et al.
(author)
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Olfactory event-related potentials reflect individual differences in odor valence perception
- 2006
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In: Chemical Senses. - : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 31:8, s. 705-711
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Journal article (peer-reviewed)abstract
- Investigating the neural substrates of perceived quality in olfaction using different odorants is intrinsically difficult. By utilizing individual differences in perceived quality of the odor of androstenone, we obtained a continuum of individual differences in rated valence of the same stimulus allowing investigations of its manifestation in the olfactory event-related potentials (ERPs). In an initial group consisting of 43 individuals that were screened for their verbal descriptors and sensitivity for the odor of androstenone, 22 normosmic volunteers were chosen forming 2 distinct groups with regard to verbal labels ("body odor" and "nonbody odor") for androstenone while maintaining chemical structure, concentration, and intensity constant. In the main experiment, these participants rated both intensity and pleasantness of androstenone during the recording of olfactory ERPs. There was a significant difference in rated valence between the groups but not in intensity. Participants in the body odor label group had larger amplitudes of the late positive ERP component than those in the nonbody odor label group. A negative correlation between valence and amplitudes of the late positive component for androstenone indicated that these differences were mediated by the difference in odor valence between the 2 groups. This was further supported by a comparison of ERP peaks in response to stimulation with androstenone and the invariably unpleasant hydrogen sulfide that had been used as a control. Altogether, the results suggest that the late positive component reflects the processing of odor valence. Future olfactory studies with the aim of assessing the dimension of pleasantness would benefit from the use of these interindividual differences in the perception of a specific odor.
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