| 1. |
- Acciari, V. A., et al.
(författare)
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Discovery of very high energy gamma rays from PKS 1424+240 and multiwavelength constraints on ITS redshift
- 2010
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Ingår i: ASTROPHYSICAL JOURNAL LETTERS. - 2041-8205. ; 708:2, s. L100-L106
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Tidskriftsartikel (refereegranskat)abstract
- We report the first detection of very high energy(83) (VHE) gamma-ray emission above 140 GeV from PKS 1424+240, a BL Lac object with an unknown redshift. The photon spectrum above 140 GeV measured by VERITAS is well described by a power law with a photon index of 3.8 +/- 0.5(stat) +/- 0.3(syst) and a flux normalization at 200 GeV of (5.1 +/- 0.9(stat) +/- 0.5(syst)) x 10(-11) TeV-1 cm(-2) s(-1), where stat and syst denote the statistical and systematical uncertainties, respectively. The VHE flux is steady over the observation period between MJD 54881 and 55003 (from 2009 February 19 to June 21). Flux variability is also not observed in contemporaneous high-energy observations with the Fermi Large Area Telescope. Contemporaneous X-ray and optical data were also obtained from the Swift XRT and MDM observatory, respectively. The broadband spectral energy distribution is well described by a one-zone synchrotron self-Compton model favoring a redshift of less than 0.1. Using the photon index measured with Fermi in combination with recent extragalactic background light absorption models it can be concluded from the VERITAS data that the redshift of PKS 1424+240 is less than 0.66.
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| 2. |
- Kessler, Jan H., et al.
(författare)
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Antigen processing by nardilysin and thimet oligopeptidase generates cytotoxic T cell epitopes
- 2010
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Ingår i: Nature Immunology. - : Springer Science and Business Media LLC. - 1529-2908 .- 1529-2916. ; 12:1, s. 45-53
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Tidskriftsartikel (refereegranskat)abstract
- Cytotoxic T lymphocytes (CTLs) recognize peptides presented by HLA class I molecules on the cell surface. The C terminus of these CTL epitopes is considered to be produced by the proteasome. Here we demonstrate that the cytosolic endopeptidases nardilysin and thimet oligopeptidase (TOP) complemented proteasome activity. Nardilysin and TOP were required, either together or alone, for the generation of a tumor-specific CTL epitope from PRAME, an immunodominant CTL epitope from Epstein-Barr virus protein EBNA3C, and a clinically important epitope from the melanoma protein MART-1. TOP functioned as C-terminal trimming peptidase in antigen processing, and nardilysin contributed to both the C-terminal and N-terminal generation of CTL epitopes. By broadening the antigenic peptide repertoire, nardilysin and TOP strengthen the immune defense against intracellular pathogens and cancer.
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| 3. |
- Vanfretti, Luigi, et al.
(författare)
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Estimation of Eastern Denmark’s electromechanical modes from ambient phasor measurement data
- 2010
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Ingår i: IEEE POWER AND ENERGY SOCIETY GENERAL MEETING 2010. - : IEEE. - 9781424483570 ; , s. 1-8
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Konferensbidrag (refereegranskat)abstract
- In this paper we report on the preliminary results of a collaborative investigation effort between researchers in North America and Europe aiming to baseline the electromechanical modes and mode shapes of the Nordic system from synchronized phasor measurement data. We provide an overview on the Danish power grid and its interconnections, and describe the features of an experimental phasor measurement unit designed by DTU which is used to provide the measurements used in this investigation. Parametric and non-parametric block processing techniques are applied to 48 hours of ambient data recorded at the Radsted and Hoveg #x00E5;rd substations in Eastern Denmark. The estimated modes are in agreement with those shown in eigenanalysis studies, and other measurement-based investigations. More importantly, the emergence of a new 0.8 Hz mode in Sj #x00E6;lland is reported.
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| 4. |
- Vanfretti, Luigi, et al.
(författare)
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Estimation of the Nigerian Power System Electromechanical Modes using FDR Measurements
- 2010
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Ingår i: Proceedings of the 9th International Conference on Power System Operations and Planning (ISCPSOP) 2010.
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Konferensbidrag (refereegranskat)abstract
- This paper reports on an ongoing research effort between researchers in North America and Africa on the study of the dynamics of loosely regulated and rapidly growing power systems, with focus on the Nigerian power network. A description of the implementation of Virginia Tech’s FDR (Frequency Disturbance Recorder) at Bauchi, Nigeria is provided. We discuss the nature of the frequency dynamics observed throughout multiple hours of a day in Nigeria and other power systems. To cater to the loosely regulated nature of the system frequency in Nigeria, we propose an appropriate method for signal conditioning which prepares the data for ambient analysis. Parametric and nonparametric block processing techniques are applied to prolonged frequency recordings ranging from 8 to 19 hours, and estimates of modal frequencies and damping are obtained by computing power spectrum densities and applying a mode meter algorithm to the ambient data. The estimated modes from ambient analysis are in agreement with other studies based on power system models.
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