| 1. |
- Raiteri, C. M., et al.
(författare)
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WEBT and XMM-Newton observations of 3C 454.3 during the post-outburst phase - Detection of the little and big blue bumps
- 2007
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 473:3, s. 819-827
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Tidskriftsartikel (refereegranskat)abstract
- Context. The quasar-type blazar 3C 454.3 was observed to undergo an unprecedented optical outburst in spring 2005, affecting the source brightness from the near-IR to the X-ray frequencies. This was first followed by a millimetric and then by a radio outburst, which peaked in February 2006. Aims. In this paper we report on follow-up observations to study the multiwavelength emission in the post-outburst phase. Methods. Radio, near-infrared, and optical monitoring was performed by the Whole Earth Blazar Telescope (WEBT) collaboration in the 2006-2007 observing season. XMM-Newton observations on July 2-3 and December 18-19, 2006 added information on the X-ray and UV states of the source. Results. The source was in a faint state. The radio flux at the higher frequencies showed a fast decreasing trend, which represents the tail of the big radio outburst. It was followed by a quiescent state, common at all radio frequencies. In contrast, moderate activity characterized the near-IR and optical light curves, with a progressive increase of the variability amplitude with increasing wavelength. We ascribe this redder-when-brighter behaviour to the presence of a ""little blue bump"" due to line emission from the broad line region, which is clearly visible in the source spectral energy distribution (SED) during faint states. Moreover, the data from the XMM- Newton Optical Monitor reveal a rise of the SED in the ultraviolet, suggesting the existence of a "" big blue bump"" due to thermal emission from the accretion disc. The X-ray spectra are well fitted with a power- law model with photoelectric absorption, possibly larger than the Galactic one. However, the comparison with previous X-ray observations would imply that the amount of absorbing matter is variable. Alternatively, the intrinsic X-ray spectrum presents a curvature, which may depend on the X-ray brightness. In this case, two scenarios are possible. i) There is no extra absorption, and the X-ray spectrum hardens at low energies, the hardening being more evident in bright states; ii) there is a constant amount of extra absorption, likely in the quasar environment, and the X-ray spectrum softens at low energies, at least in faint X-ray states. This softening might be the result of a flux contribution by the high-frequency tail of the big blue bump.
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| 2. |
- Amanullah, Rahman, et al.
(författare)
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Spectra and Hubble Space Telescope Light Curves of Six Type Ia Supernovae at 0.511 < z < 1.12 and the Union2 Compilation
- 2010
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 716, s. 712-738
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Tidskriftsartikel (refereegranskat)abstract
- We report on work to increase the number of well-measured Type Ia supernovae (SNe Ia) at high redshifts. Light curves, including high signal-to-noise Hubble Space Telescope data, and spectra of six SNe Ia that were discovered during 2001, are presented. Additionally, for the two SNe with z > 1, we present ground-based J-band photometry from Gemini and the Very Large Telescope. These are among the most distant SNe Ia for which ground-based near-IR observations have been obtained. We add these six SNe Ia together with other data sets that have recently become available in the literature to the Union compilation. We have made a number of refinements to the Union analysis chain, the most important ones being the refitting of all light curves with the SALT2 fitter and an improved handling of systematic errors. We call this new compilation, consisting of 557 SNe, the Union2 compilation. The flat concordance ΛCDM model remains an excellent fit to the Union2 data with the best-fit constant equation-of-state parameter w = -0.997+0.050 -0.054(stat)+0.077 -0.082(stat + sys together) for a flat universe, or w = -1.038+0.056 -0.059(stat)+0.093 -0.097(stat + sys together) with curvature. We also present improved constraints on w(z). While no significant change in w with redshift is detected, there is still considerable room for evolution in w. The strength of the constraints depends strongly on redshift. In particular, at z >~ 1, the existence and nature of dark energy are only weakly constrained by the data. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute (STScI). STScI is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under the NASA contract NAS 5-26555. The observations are associated with programs HST-GO-08585 and HST-GO-09075. Based, in part, on observations obtained at the ESO La Silla Paranal Observatory (ESO programs 67.A-0361 and 169.A-0382). Based, in part, on observations obtained at the Cerro-Tololo Inter-American Observatory (CTIO), National Optical Astronomy Observatory (NOAO). Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT). Based, in part, on observations obtained at the Gemini Observatory (Gemini programs GN-2001A-SV-19 and GN-2002A-Q-31). Based, in part on observations obtained at the Subaru Telescope. Based, in part, on data that were obtained at the W. M. Keck Observatory.
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| 3. |
- Trelsmo, P., et al.
(författare)
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Evaluating IPv6 Connectivity for IEEE 802.15.4 and Bluetooth Low Energy
- 2017
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Ingår i: 2017 IEEE Wireless Communications and Networking Conference Workshops, WCNCW 2017.
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Konferensbidrag (refereegranskat)abstract
- IPv6 is seen as a key building block for the Internet of Things (IoT). In this work, IEEE 802.15.4 and Bluetooth Low Energy (BLE) protocols are evaluated with respect to service ratio, delay, and energy efficiency under IPv6 traffic. While the performance is terms of delay is similar between the two technologies, BLE outperforms 802.15.4 in terms of service ratio and energy efficiency. Header compression increases all performance indicators but requires a shared context to be set up and managed. IPv6 multicast is also investigated in combination with data link layer broadcast and sequential unicast. Finally, the impact of IPv6 connection establishment and maintenance is evaluated. This is particularly relevant for BLE devices using privacy features. It is shown that the procedures for registering IPv6 addresses and updating contexts affect the delay significantly, but only at very low traffic intensity.
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| 4. |
- Berciano Alba, A., et al.
(författare)
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DEMON: a proposal for a satellite-borne experiment to study dark matter and dark energy
- 2006
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Ingår i: Proceedings of the SPIE: Space Telescopes and Instrumentation II: Ultraviolet to Gamma Ray, eds, M.J.L. Turner and G. Hasinger. ; 6266, s. 91-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We outline a novel satellite mission concept, DEMON, aimed at advancing our comprehension of both dark matter and dark energy, taking full advantage of two complementary methods: weak lensing and the statistics of galaxy clusters. We intend to carry out a 5000 deg2 combined IR, optical and X-ray survey with galaxies up to a redshift of z~2 in order todetermine the shear correlation function. We will also find ~100000 galaxy clusters, making it the largest survey of this type to date. The DEMON spacecraft will comprise one IR/optical and eight X-ray telescopes,coupled to multiple cameras operating at different frequency bands. To a great extent, the technology employed has already been partially tested on ongoing missions, therefore ensuring improved reliability.
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| 5. |
- Hansson, Lars, et al.
(författare)
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Mannequin Properties Desired for Ergonomic Evaluation of Car Interiors
- 1998
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- An example of a result from a long-term cooperation with Lund University (together with professor Roland Akselsson at the Department of Ergonomics and Aerosol Technology) there some of the authors. (Engström) gained extensive grants (EU-financing and Wallenberg Stifelsen regarding equipment as well as other founding from e.g. the Swedish Work Environment Found). This publication has emanated from an EU-financed research project.
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| 6. |
- Lilja, Gisela, et al.
(författare)
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Anxiety and depression among out-of-hospital cardiac arrest survivors.
- 2015
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Ingår i: Resuscitation. - : Elsevier BV. - 1873-1570 .- 0300-9572. ; 97, s. 68-75
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Tidskriftsartikel (refereegranskat)abstract
- Survivors of out-of-hospital cardiac arrest (OHCA) may experience psychological distress but the actual prevalence is unknown. The aim of this study was to investigate anxiety and depression within a large cohort of OHCA-survivors.
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| 7. |
- Nordin, Jakob, et al.
(författare)
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Spectral properties of Type Ia supernovae up to z~0.3
- 2011
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 526, s. A119-
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Spectroscopic observations of type Ia supernovae obtained at the New Technology Telescope (NTT) and the Nordic Optical Telescope (NOT), in conjunction with the SDSS-II Supernova Survey, are analysed. We use spectral indicators measured up to a month after the lightcurve peak luminosity to characterise the supernova properties, and examine these for potential correlations with host galaxy type, lightcurve shape, colour excess, and redshift. Methods: Our analysis is based on 89 type Ia supernovae at a redshift interval z = 0.05-0.3, for which multiband SDSS photometry is available. A lower-z spectroscopy reference sample was used for comparisons over cosmic time. We present measurements of time series of pseudo equivalent widths and line velocities of the main spectral features in type Ia supernovae. Results: Supernovae with shallower features are found predominantly among the intrinsically brighter slow declining supernovae. We detect the strongest correlation between lightcurve stretch and the Si ii λ4000 absorption feature, which also correlates with the estimated mass and star formation rate of the host galaxy. We also report a tentative correlation between colour excess and spectral properties. If confirmed, this would suggest that moderate reddening of type Ia supernovae is dominated by effects in the explosion or its immediate environment, as opposed to extinction by interstellar dust.
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| 8. |
- Sjöblom, Tobias, et al.
(författare)
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Growth inhibition of dermatofibrosarcoma protuberans tumors by the platelet-derived growth factor receptor antagonist STI571 through induction of apoptosis.
- 2001
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Ingår i: Cancer Res. - 0008-5472. ; 61:15, s. 5778-83
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Tidskriftsartikel (refereegranskat)abstract
- Dermatofibrosarcoma protuberans (DFSP) and giant cell fibroblastoma (GCF) are recurrent, infiltrative skin tumors that presently are treated with surgery. DFSP and GCF tumors are genetically characterized by chromosomal rearrangements fusing the collagen type Ialpha1 (COLIA1) gene to the platelet-derived growth factor B-chain (PDGFB) gene. It has been shown that the resulting COL1A1/PDGF-B fusion protein is processed to mature PDGF-BB. Autocrine PDGF receptor stimulation has therefore been predicted to contribute to DFSP and GCF tumor development and growth. Here we demonstrate presence of activated PDGF receptors in primary cultures derived from six different DFSP and GCF tumors. Three of the primary cultures were further characterized; their in vitro growth displayed an increased sensitivity to treatment with the PDGF receptor tyrosine kinase inhibitor STI571, as compared with normal fibroblasts. Transplantable tumors, displaying a DFSP-like histology, were established from one of the DFSP primary cultures. Treatment of tumor-bearing severe combined immunodeficient mice with STI571 reduced tumor growth. The growth-inhibitory effects in vitro and in vivo occurred predominantly through induction of tumor cell apoptosis. Our study demonstrates growth-inhibitory effects of PDGF receptor antagonists on human DFSP- and GCF-derived tumor cells and demonstrates that autocrine PDGF receptor stimulation provides antiapoptotic signals contributing to the growth of these cells. These findings suggest targeting of PDGF receptors as a novel treatment strategy for DFSP and GCF.
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| 9. |
- Stanishev, Vallery, et al.
(författare)
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Type Ia supernova Hubble diagram with near-infrared and optical observations
- 2018
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 615
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Tidskriftsartikel (refereegranskat)abstract
- Context. Type Ia Supernovae (SNe Ia) have been used as standardizable candles in the optical wavelengths to measure distances with an accuracy of similar to 7% out to redshift z similar to 1 : 5. There is evidence that in the near-infrared (NIR) wavelengths SNe Ia are even better standard candles, however, NIR observations are much more time-consuming.Aims. We aim to test whether the NIR peak magnitudes could be accurately estimated with only a single observation obtained close to maximum light, provided that the time of B band maximum, the B - V color at maximum and the optical stretch parameter are known.Methods. We present multi-epoch UBVRI and single-epoch J and H photometric observations of 16 SNe Ia in the redshift range z = 0 : 037 0 : 183, doubling the leverage of the current SN Ia NIR Hubble diagram and the number of SNe beyond redshift 0.04. This sample was analyzed together with 102 NIR and 458 optical light curves (LCs) of normal SNe Ia from the literature.Results. The analysis of 45 NIR LCs with well-sampled first maximum shows that a single template accurately describes the LCs if its time axis is stretched with the optical stretch parameter. This allows us to estimate the peak NIR magnitudes of SNe with only few observations obtained within ten days from B-band maximum. The NIR Hubble residuals show weak correlation with Delta M-15 and the color excess E(B V), and for the first time we report a potential dependence on the J(max) - H-max color. With these corrections, the intrinsic NIR luminosity scatter of SNe Ia is estimated to be similar to 0.10 mag, which is smaller than what can be derived for a similarly heterogeneous sample at optical wavelengths. Analysis of both NIR and optical data shows that the dust extinction in the host galaxies corresponds to a low R-V similar or equal to 1.8-1.9.Conclusions. We conclude that SNe Ia are at least as good standard candles in the NIR as in the optical and are potentially less affected by systematic uncertainties. We extended the NIR SN Ia Hubble diagram to its nonlinear part at z similar to 0 : 2 and confirmed that it is feasible to accomplish this result with very modest sampling of the NIR LCs, if complemented by well-sampled optical LCs. With future facilities it will be possible to extend the NIR Hubble diagram beyond redshift z similar or equal to 1; and our results suggest that the most efficient way to achieve this would be to obtain a single observation close to the NIR maximum.
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| 10. |
- Östman, Linda, et al.
(författare)
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NTT and NOT spectroscopy of SDSS-II supernovae
- 2011
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 526, s. A28-
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Tidskriftsartikel (refereegranskat)abstract
- Context. The Sloan Digital Sky Survey II (SDSS-II) Supernova Survey, conducted between 2005 and 2007, was designed to detect a large number of type Ia supernovae around z ~ 0.2, the redshift "gap" between low-z and high-z supernova searches. The survey has provided multi-band (ugriz) photometric lightcurves for variable targets, and supernova candidates were scheduled for spectroscopic observations, primarily to provide supernova classification and accurate redshifts. We present supernova spectra obtained in 2006 and 2007 using the New Technology Telescope (NTT) and the Nordic Optical Telescope (NOT). Aims: We provide an atlas of supernova spectra in the range z = 0.03-0.32 that complements the well-sampled lightcurves from SDSS-II in the forthcoming three-year SDSS supernova cosmology analysis. The sample can, for example, be used for spectral studies of type Ia supernovae, which are critical for understanding potential systematic effects when supernovae are used to determine cosmological distances. Methods: The spectra were reduced in a uniform manner, and special care was taken in estimating the uncertainties for the different processing steps. Host-galaxy light was subtracted when possible and the supernova type fitted using the SuperNova IDentification code (SNID). We also present comparisons between spectral and photometric dating using SALT lightcurve fits to the photometry from SDSS-II, as well as the global distribution of our sample in terms of the lightcurve parameters: stretch and colour. Results: We report new spectroscopic data from 141 type Ia supernovae, mainly between -9 and +15 days from lightcurve maximum, including a few cases of multi-epoch observations. This homogeneous, host-galaxy subtracted, type Ia supernova spectroscopic sample is among the largest such data sets and unique in its redshift interval. The sample includes two potential SN 1991T-like supernovae (SN 2006on and SN 2007ni) and one potential SN 2002cx-like supernova (SN 2007ie). In addition, the new compilation includes spectra from 23 confirmed type II and 8 type Ib/c supernovae.
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