Change search
Refine search result
19202122232425 1051 - 1100 of 102039
Cite
Citation style
• apa
• ieee
• modern-language-association-8th-edition
• vancouver
• Other style
More styles
Language
• de-DE
• en-GB
• en-US
• fi-FI
• nn-NO
• nn-NB
• sv-SE
• Other locale
More languages
Output format
• html
• text
• asciidoc
• rtf
Rows per page
• 5
• 10
• 20
• 50
• 100
• 250
Sort
• Standard (Relevance)
• Author A-Ö
• Author Ö-A
• Title A-Ö
• Title Ö-A
• Publication type A-Ö
• Publication type Ö-A
• Issued (Oldest first)
• Created (Oldest first)
• Last updated (Oldest first)
• Disputation date (earliest first)
• Disputation date (latest first)
• Standard (Relevance)
• Author A-Ö
• Author Ö-A
• Title A-Ö
• Title Ö-A
• Publication type A-Ö
• Publication type Ö-A
• Issued (Oldest first)
• Created (Oldest first)
• Last updated (Oldest first)
• Disputation date (earliest first)
• Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
• 1051. Ackermann, M.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
FERMI-LAT SEARCH FOR PULSAR WIND NEBULAE AROUND GAMMA-RAY PULSARS2011In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 726, no 1, p. 35-Article in journal (Refereed)

The high sensitivity of the Fermi-LAT (Large Area Telescope) offers the first opportunity to study faint and extended GeV sources such as pulsar wind nebulae (PWNe). After one year of observation the LAT detected and identified three PWNe: the Crab Nebula, Vela-X, and the PWN inside MSH 15-52. In the meantime, the list of LAT detected pulsars increased steadily. These pulsars are characterized by high energy loss rates ((E) over dot) from similar to 3 x 10(33) erg s(-1) to 5 x 10(38) erg s(-1) and are therefore likely to power a PWN. This paper summarizes the search for PWNe in the off-pulse windows of 54 LAT-detected pulsars using 16 months of survey observations. Ten sources show significant emission, seven of these likely being of magnetospheric origin. The detection of significant emission in the off-pulse interval offers new constraints on the gamma-ray emitting regions in pulsar magnetospheres. The three other sources with significant emission are the Crab Nebula, Vela-X, and a new PWN candidate associated with the LAT pulsar PSR J1023-5746, coincident with the TeV source HESS J1023-575. We further explore the association between the HESS and the Fermi source by modeling its spectral energy distribution. Flux upper limits derived for the 44 remaining sources are used to provide new constraints on famous PWNe that have been detected at keV and/or TeV energies.

• 1052. Ackermann, M.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
CONSTRAINTS ON THE COSMIC-RAY DENSITY GRADIENT BEYOND THE SOLAR CIRCLE FROM FERMI gamma-RAY OBSERVATIONS OF THE THIRD GALACTIC QUADRANT2011In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 726, no 2, p. 81-Article in journal (Refereed)

We report an analysis of the interstellar gamma-ray emission in the third Galactic quadrant measured by the Fermi Large Area Telescope. The window encompassing the Galactic plane from longitude 210 degrees to 250 degrees has kinematically well-defined segments of the Local and the Perseus arms, suitable to study the cosmic-ray (CR) densities across the outer Galaxy. We measure no large gradient with Galactocentric distance of the gamma-ray emissivities per interstellar H atom over the regions sampled in this study. The gradient depends, however, on the optical depth correction applied to derive the H I column densities. No significant variations are found in the interstellar spectra in the outer Galaxy, indicating similar shapes of the CR spectrum up to the Perseus arm for particles with GeV to tens of GeV energies. The emissivity as a function of Galactocentric radius does not show a large enhancement in the spiral arms with respect to the interarm region. The measured emissivity gradient is flatter than expectations based on a CR propagation model using the radial distribution of supernova remnants and uniform diffusion properties. In this context, observations require a larger halo size and/or a flatter CR source distribution than usually assumed. The molecular mass calibrating ratio, X(CO) = N(H(2))/W(CO), is found to be (2.08 +/- 0.11) x 10(20) cm(-2)(K km s(-1))(-1) in the Local arm clouds and is not significantly sensitive to the choice of Hi spin temperature. No significant variations are found for clouds in the interarm region.

• 1053. Ackermann, M.
Stockholm University, Nordic Institute for Theoretical Physics (Nordita). University of Iceland, Iceland.
The Search for Spatial Extension in High-latitude Sources Detected by the Fermi Large Area Telescope2018In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 237, no 2, article id 32Article in journal (Refereed)

We present a search for spatial extension in high-latitude (vertical bar b vertical bar > 5 degrees) sources in recent Fermi point source catalogs. The result is the Fermi High-Latitude Extended Sources Catalog, which provides source extensions (or upper limits thereof) and likelihood profiles for a suite of tested source morphologies. We find 24. extended sources, 19 of which were not previously characterized as extended. These include sources that are potentially associated with supernova remnants and star-forming regions. We also found extended.-ray emission in the vicinity of the Cen. A radio lobes and-at GeV energies for the first time-spatially coincident with the radio emission of the SNR CTA 1, as well as from the Crab Nebula. We also searched for halos around active galactic nuclei, which are predicted from electromagnetic cascades induced by the e(+)e(-) pairs that are deflected in intergalactic magnetic fields. These pairs are produced when gamma-rays interact with background radiation fields. We do not find evidence for extension in individual sources or in stacked source samples. This enables us to place limits on the flux of the extended source components, which are then used to constrain the intergalactic magnetic field to be stronger than 3 x 10(-16) G for a coherence length lambda greater than or similar to 10 kpc, even when conservative assumptions on the source duty cycle are made. This improves previous limits by several orders of magnitude.

• 1054. Ackermann, M.
Stockholm University, Nordic Institute for Theoretical Physics (Nordita). University of Iceland, Iceland.
Unresolved Gamma-Ray Sky through its Angular Power Spectrum2018In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 121, no 24, article id 241101Article in journal (Refereed)

The gamma-ray sky has been observed with unprecedented accuracy in the last decade by the Fermi-large area telescope (LAT), allowing us to resolve and understand the high-energy Universe. The nature of the remaining unresolved emission [unresolved gamma-ray background (UGRB)] below the LAT source detection threshold can be uncovered by characterizing the amplitude and angular scale of the UGRB fluctuation field. This Letter presents a measurement of the UGRB autocorrelation angular power spectrum based on eight years of Fermi-LAT Pass 8 data products. The analysis is designed to be robust against contamination from resolved sources and noise systematics. The sensitivity to subthreshold sources is greatly enhanced with respect to previous measurements. We find evidence (with similar to 3.7 sigma significance) that the scenario in which two classes of sources contribute to the UGRB signal is favored over a single class. A double power law with exponential cutoff can explain the anisotropy energy spectrum well, with photon indices of the two populations being 2.55 +/- 0.23 and 1.86 +/- 0.15.

• 1055. Ackermann, M.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
Gamma-Ray Blazars within the First 2 Billion Years2017In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 837, no 1, article id L5Article in journal (Refereed)

The detection of high-redshift (z > 3) blazars enables the study of the evolution of the most luminous relativistic jets over cosmic time. More importantly, high-redshift blazars tend to host massive black holes and can be used to constrain the space density of heavy black holes in the early universe. Here, we report the first detection with the Fermi-Large Area Telescope of five gamma-ray-emitting blazars beyond z. =. 3.1, more distant than any blazars previously detected in.-rays gamma Among these five objects, NVSS J151002+570243 is now the most distant known gamma-ray-emitting blazar at z =. 4.31. These objects have steeply falling gamma-ray spectral energy distributions (SEDs), and. those that have been observed in X-rays have a very hard X-ray spectrum, both typical of powerful blazars. Their Compton dominance ( ratio of the inverse Compton to synchrotron peak luminosities) is also very large (>20). All of these properties place these objects among the most extreme members of the blazar population. Their optical spectra and the modeling of their optical-UV SEDs confirm that these objects harbor massive black holes (MBH similar to 10(8-10) M circle dot 8 10). We find that, at z approximate to 4, the space density of >10(9)M circle dot black holes hosted in radio-loud and radio-quiet active galactic nuclei are similar, implying that radio-loudness may play a key role in rapid black hole growth in the early universe.

• 1056. Ackermann, M.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
Periodic Emission from the Gamma-Ray Binary 1FGL J1018.6-58562012In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 335, no 6065, p. 189-193Article in journal (Refereed)

Gamma-ray binaries are stellar systems containing a neutron star or black hole, with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy. A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL J1018.6-5856 exhibits intensity and spectral modulation with a 16.6-day period. We identified a variable x-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an O6V((f)) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. 1FGL J1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy.

• 1057. Ackermann, M.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
MULTI-WAVELENGTH OBSERVATIONS OF BLAZAR AO 0235+164 IN THE 2008-2009 FLARING STATE2012In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 751, no 2, article id 159Article in journal (Refereed)

The blazarAO 0235+164 (z=0.94) has been one of the most active objects observed by Fermi Large Area Telescope (LAT) since its launch in Summer 2008. In addition to the continuous coverage by Fermi, contemporaneous observations were carried out from the radio to gamma-ray bands between 2008 September and 2009 February. In this paper, we summarize the rich multi-wavelength data collected during the campaign (including F-GAMMA, GASP-WEBT, Kanata, OVRO, RXTE, SMARTS, Swift, and other instruments), examine the cross-correlation between the light curves measured in the different energy bands, and interpret the resulting spectral energy distributions in the context of well-known blazar emission models. We find that the gamma-ray activity is well correlated with a series of near-IR/optical flares, accompanied by an increase in the optical polarization degree. On the other hand, the X-ray light curve shows a distinct 20 day high state of unusually soft spectrum, which does not match the extrapolation of the optical/UV synchrotron spectrum. We tentatively interpret this feature as the bulk Compton emission by cold electrons contained in the jet, which requires an accretion disk corona with an effective covering factor of 19% at a distance of 100 R-g. We model the broadband spectra with a leptonic model with external radiation dominated by the infrared emission from the dusty torus.

• 1058. Ackermann, M.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Univ Udine, Dipartimento Fis, I-33100 Udine, Italy. Stockholm University, Faculty of Science, Department of Astronomy. st Nazl Fis Nucl, Sez Torino, I-10125 Turin, Italy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Ist Nazl Fis Nucl, Sez Torino, I-10125 Turin, Italy.
ASSOCIATING LONG-TERM gamma-RAY VARIABILITY WITH THE SUPERORBITAL PERIOD OF LS I+61 degrees 3032013In: ASTROPHYSICAL JOURNAL LETTERS, ISSN 2041-8205, Vol. 773, no 2, p. L35-Article in journal (Refereed)

Gamma-ray binaries are stellar systems for which the spectral energy distribution (discounting the thermal stellar emission) peaks at high energies. Detected from radio to TeV gamma rays, the gamma-ray binary LS I + 61 degrees 303 is highly variable across all frequencies. One aspect of this system's variability is the modulation of its emission with the timescale set by the similar to 26.4960 day orbital period. Here we show that, during the time of our observations, the gamma-ray emission of LS I + 61 degrees 303 also presents a sinusoidal variability consistent with the previously known superorbital period of 1667 days. This modulation is more prominently seen at orbital phases around apastron, whereas it does not introduce a visible change close to periastron. It is also found in the appearance and disappearance of variability at the orbital period in the power spectrum of the data. This behavior could be explained by a quasi-cyclical evolution of the equatorial outflow of the Be companion star, whose features influence the conditions for generating gamma rays. These findings open the possibility to use gamma-ray observations to study the outflows of massive stars in eccentric binary systems.

• 1059. Ackermann, M.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Wallenberg Academy Fellow, Sweden. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
Searching for Dark Matter Annihilation from Milky Way Dwarf Spheroidal Galaxies with Six Years of Fermi Large Area Telescope Data2015In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 115, no 23, article id 231301Article in journal (Refereed)

The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some of the most dark matter (DM) dominated objects known. We report on gamma-ray observations of Milky Way dSphs based on six years of Fermi Large Area Telescope data processed with the new PASS8 event-level analysis. None of the dSphs are significantly detected in gamma rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15 dSphs. These constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DM of mass less than or similar to 100 GeV annihilating via quark and tau-lepton channels.

• 1060. Ackermann, M.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
Dark matter constraints from observations of 25 Milky Way satellite galaxies with the Fermi Large Area Telescope2014In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 89, no 4, article id 042001Article in journal (Refereed)

The dwarf spheroidal satellite galaxies of the Milky Way are some of the most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack of astrophysical backgrounds, dwarf spheroidal galaxies are widely considered to be among the most promising targets for the indirect detection of dark matter via gamma rays. Here we report on.-ray observations of 25 Milky Way dwarf spheroidal satellite galaxies based on 4 years of Fermi Large Area Telescope (LAT) data. None of the dwarf galaxies are significantly detected in. rays, and we present.-ray flux upper limits between 500 MeV and 500 GeV. We determine the dark matter content of 18 dwarf spheroidal galaxies from stellar kinematic data and combine LAT observations of 15 dwarf galaxies to constrain the dark matter annihilation cross section. We set some of the tightest constraints to date on the annihilation of dark matter particles with masses between 2 GeV and 10 TeV into prototypical standard model channels. We find these results to be robust against systematic uncertainties in the LAT instrument performance, diffuse.-ray background modeling, and assumed dark matter density profile.

• 1061. Ackermann, M.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Royal Swedish Academy of Science, Sweden. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
THE SPECTRUM AND MORPHOLOGY OF THE FERMI BUBBLES2014In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 793, no 1, p. 64-Article in journal (Refereed)

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.

• 1062. Ackermann, M.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
Deep view of the Large Magellanic Cloud with six years of Fermi-LAT observations2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 586, article id A71Article in journal (Refereed)

Context. The nearby Large Magellanic Cloud (LMC) provides a rare opportunity of a spatially resolved view of an external star-forming galaxy in gamma-rays. The LMC was detected at 0.1-100 GeV as an extended source with CGRO/EGRET and using early observations with the Fermi-LAT. The emission was found to correlate with massive star-forming regions and to be particularly bright towards 30 Doradus. Aims. Studies of the origin and transport of cosmic rays (CRs) in the Milky Way are frequently hampered by line-of-sight confusion and poor distance determination. The LMC offers a complementary way to address these questions by revealing whether and how the gamma-ray emission is connected to specific objects, populations of objects, and structures in the galaxy. Methods. We revisited the gamma-ray emission from the LMC using about 73 months of Fermi-LAT P7REP data in the 0.2-100 GeV range. We developed a complete spatial and spectral model of the LMC emission, for which we tested several approaches: a simple geometrical description, template-fitting, and a physically driven model for CR-induced interstellar emission. Results. In addition to identifying PSR J0540-6919 through its pulsations, we find two hard sources positionally coincident with plerion N 157B and supernova remnant N 132D, which were also detected at TeV energies with H.E.S.S. We detect an additional soft source that is currently unidentified. Extended emission dominates the total flux from the LMC. It consists of an extended component of about the size of the galaxy and additional emission from three to four regions with degree-scale sizes. If it is interpreted as CRs interacting with interstellar gas, the large-scale emission implies a large-scale population of similar to 1-100 GeV CRs with a density of similar to 30% of the local Galactic value. On top of that, the three to four small-scale emission regions would correspond to enhancements of the CR density by factors 2 to 6 or higher, possibly more energetic and younger populations of CRs compared to the large-scale population. An alternative explanation is that this is emission from an unresolved population of at least two dozen objects, such as pulsars and their nebulae or supernova remnants. This small-scale extended emission has a spatial distribution that does not clearly correlate with known components of the LMC, except for a possible relation to cavities and supergiant shells. Conclusions. The Fermi-LAT GeV observations allowed us to detect individual sources in the LMC. Three of the newly discovered sources are associated with rare and extreme objects. The 30 Doradus region is prominent in GeV gamma-rays because PSR J0540-6919 and N 157B are strong emitters. The extended emission from the galaxy has an unexpected spatial distribution, and observations at higher energies and in radio may help to clarify its origin.

• 1063. Ackermann, M.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
SEARCH FOR DARK MATTER SATELLITES USING FERMI-LAT2012In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 747, no 2, p. 121-Article in journal (Refereed)

Numerical simulations based on the ACDM model of cosmology predict a large number of as yet unobserved Galactic dark matter satellites. We report the results of a Large Area Telescope (LAT) search for these satellites via the gamma-ray emission expected from the annihilation of weakly interacting massive particle (WIMP) dark matter. Some dark matter satellites are expected to have hard gamma-ray spectra, finite angular extents, and a lack of counterparts at other wavelengths. We sought to identify LAT sources with these characteristics, focusing on gamma-ray spectra consistent with WIMP annihilation through the b (b) over bar channel. We found no viable dark matter satellite candidates using one year of data, and we present a framework for interpreting this result in the context of numerical simulations to constrain the velocity-averaged annihilation cross section for a conventional 100 GeV WIMP annihilating through the b (b) over bar channel.

• 1064. Ackermann, M.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
SEARCH FOR EARLY GAMMA-RAY PRODUCTION IN SUPERNOVAE LOCATED IN A DENSE CIRCUMSTELLAR MEDIUM WITH THE FERMI LAT2015In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 807, no 2, article id 169Article in journal (Refereed)

Supernovae (SNe) exploding in a dense circumstellar medium (CSM) are hypothesized to accelerate cosmic rays in collisionless shocks and emit GeV gamma-rays and TeV neutrinos on a timescale of several months. We perform the first systematic search for gamma-ray emission in Fermi Large Area Telescope data in the energy range from 100 MeV to 300 GeV from the ensemble of 147 SNe Type IIn exploding in a dense CSM. We search for a gamma-ray excess at each SNe location in a one-year time window. In order to enhance a possible weak signal, we simultaneously study the closest and optically brightest sources of our sample in a joint-likelihood analysis in three different time windows (1 year, 6 months, and 3 months). For the most promising source of the sample, SN 2010jl (PTF 10aaxf), we repeat the analysis with an extended time window lasting 4.5 years. We do not find a significant excess in gamma-rays for any individual source nor for the combined sources and provide model-independent flux upper limits for both cases. In addition, we derive limits on the gamma-ray luminosity and the ratio of gamma-ray-to-optical luminosity ratio as a function of the index of the proton injection spectrum assuming a generic gamma-ray production model. Furthermore, we present detailed flux predictions based on multi-wavelength observations and the corresponding flux upper limit at a 95% confidence level (CL) for the source SN 2010jl (PTF 10aaxf).

• 1065. Ackermann, M.
Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
Search for Gamma-Ray Emission from Local Primordial Black Holes with the Fermi Large Area Telescope2018In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 857, no 1, article id 49Article in journal (Refereed)

Black holes with masses below approximately 10(15) g are expected to emit gamma-rays with energies above a few tens of MeV, which can be detected by the Fermi Large Area Telescope (LAT). Although black holes with these masses cannot be formed as a result of stellar evolution, they may have formed in the early universe and are therefore called primordial black holes (PBHs). Previous searches for PBHs have focused on either short-timescale bursts or the contribution of PBHs to the isotropic gamma-ray emission. We show that, in cases of individual PBHs, the Fermi-LAT is most sensitive to PBHs with temperatures above approximately 16 GeV and masses 6 x 10(11) g, which it can detect out to a distance of about 0.03 pc. These PBHs have a remaining lifetime of months to years at the start of the Fermi mission. They would appear as potentially moving point sources with gamma-ray emission that become spectrally harder and brighter with time until the PBH completely evaporates. In this paper, we develop a new algorithm to detect the proper motion of gamma-ray point sources, and apply it to 318 unassociated point sources at a high galactic latitude in the third Fermi-LAT source catalog. None of the unassociated point sources with spectra consistent with PBH evaporation show significant proper motion. Using the nondetection of PBH candidates, we derive a 99% confidence limit on the PBH evaporation rate in the vicinity of Earth, <(rho)over dot>(PBH) < 7.2 x 10(3) pc(-3) yr(-1). This limit is similar to the limits obtained with ground-based gamma-ray observatories.

• 1066. Ackermann, M.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
MULTIFREQUENCY STUDIES OF THE PECULIAR QUASAR 4C+21.35 DURING THE 2010 FLARING ACTIVITY2014In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 786, no 2, p. 157-Article in journal (Refereed)

The discovery of rapidly variable Very High Energy ( VHE; E > 100 GeV). - ray emission from 4C + 21.35 ( PKS 1222+ 216) by MAGIC on 2010 June 17, triggered by the high activity detected by the Fermi Large Area Telescope ( LAT) in high energy ( HE; E > 100 MeV). - rays, poses intriguing questions on the location of the. - ray emitting region in this flat spectrum radio quasar. We present multifrequency data of 4C + 21.35 collected from centimeter to VHE during 2010 to investigate the properties of this source and discuss a possible emission model. The first hint of detection at VHE was observed by MAGIC on 2010 May 3, soon after a gamma- ray flare detected by Fermi-LAT that peaked on April 29. The same emission mechanism may therefore be responsible for both the HE and VHE emission during the 2010 flaring episodes. Two optical peaks were detected on 2010 April 20 and June 30, close in time but not simultaneous with the two gamma- ray peaks, while no clear connection was observed between the X-ray and gamma- ray emission. An increasing flux density was observed in radio and mm bands from the beginning of 2009, in accordance with the increasing gamma- ray activity observed by Fermi-LAT, and peaking on 2011 January 27 in the mm regime ( 230 GHz). We model the spectral energy distributions ( SEDs) of 4C + 21.35 for the two periods of the VHE detection and a quiescent state, using a one-zone model with the emission coming from a very compact region outside the broad line region. The three SEDs can be fit with a combination of synchrotron self-Compton and external Compton emission of seed photons from a dust torus, changing only the electron distribution parameters between the epochs. The fit of the optical/UV part of the spectrum for 2010 April 29 seems to favor an inner disk radius of < six gravitational radii, as one would expect from a prograde-rotating Kerr black hole.

• 1067. Ackermann, Nils
Stockholm University, Faculty of Science, Department of Mathematics.
A concentration phenomenon for semilinear elliptic equations2013In: Archive for Rational Mechanics and Analysis, ISSN 0003-9527, E-ISSN 1432-0673, Vol. 207, no 3, p. 1075-1089Article in journal (Refereed)

For a domain $\Omega\subset\dR^N$ we consider the equation $-\Delta u + V(x)u = Q_n(x)\abs{u}^{p-2}u$ with zero Dirichlet boundary conditions and $p\in(2,2^*)$. Here $V\ge 0$ and $Q_n$ are bounded functions that are positive in a region contained in $\Omega$ and negative outside, and such that the sets $\{Q_n>0\}$ shrink to a point $x_0\in\Omega$ as $n\to\infty$. We show that if $u_n$ is a nontrivial solution corresponding to $Q_n$, then the sequence $(u_n)$ concentrates at $x_0$ with respect to the $H^1$ and certain $L^q$-norms. We also show that if the sets $\{Q_n>0\}$ shrink to two points and $u_n$ are ground state solutions, then they concentrate at one of these points.

• 1068.
Stockholm University, Faculty of Social Sciences, Department of Social Work.
Att drabbas av kronisk sjukdom: En studie om livsomställningen efter hjärtinfarkt2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis

This study aims to highlight the crisis and adjustment process in individuals who suffered myocardial infarction. The research questions focus on the informants’ experiences of the crisis and life adjustment process, and illuminate the coping strategies that the informants describe important. By using a narrative method and applyingthe crisis theory and coping theory as theoretical guidelines, this study endeavors to illuminate individuals' experiences of the disease from their own perspective. The empirical material consists of four life stories gatheredthrough semi-structured interviews. The result indicates general patterns that characterize the course of the diseaseat the same time as individual aspectsof the crisis process are shown, where individual coping strategies have proven necessary through the different phases. The individual aspect on how one cope with crisis seems to depend on personality and life situation. Major life adjustments have proven necessary in the course of the disease. Changes and priorities seem to be revalued through the different phases, along with a greater appreciation for life. Importance of social support is being emphasized; however the most important element appears to be their own, personalefforts and transformation.

• 1069.
Stockholm University, Faculty of Humanities, Department of Media Studies.
Kampen det varit tyst om: Svenska rösträttskvinnorna kämpade i 20 år2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis

Den svenska kvinnorösträttskampen har osynliggjorts i den nationella historieskrivningen om demokratiseringsprocessen. De engelska suffragetternas kamp är känd, och hur de offrade sina kroppar för rösträtten. Men de svenska rösträttskvinnorna offrade också sina kroppar för rösträtten i en nära 20 år lång kamp med hårt motstånd. Det är en förvånansvärt okänd och oberättad historia - trots att rösträtt för kvinnor är en grundläggande förutsättning för demokrati och medborgarskap. Här berättas storyn om "Landsföreningen för kvinnas politiska rösträtt" och dess ledare Signe Bergman.

• 1070.
Stockholm University, Faculty of Social Sciences, School of Business.
Stockholm University, Faculty of Social Sciences, School of Business.
Fed Modellen: Ett motiverat värderingsverktyg?: Test på den svenska marknaden2005Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis

Börsvärdering har traditionellt sätt inneburit en svår uppgift och erfarenheten visar att föreställningarna om framtiden inte alltid varit så realistiska, vilket tidvis banat väg för finansiella bubblor. Efterfrågan på en enkel värderingsmodell fick Federal Reserve att agera och utveckla ”The Fed-Model”.

• 1071.
Stockholm University, Faculty of Social Sciences, School of Business.
Stockholm University, Faculty of Social Sciences, School of Business.
Insynshandel i tillväxtbolag: En studie av Aktietorget och Nordic Growth Market2006Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis

Tidigare forskning har indikerat att det kan existera informationsasymmetrier i aktiemarknaden mellan olika marknadsaktörer. Personer med insyn har oftast tillgång till särskild information som inte är tillgänglig för marknaden. Detta innebär att möjligheter till abnormala avkastningar existerar för dessa personer vid handel av bolagets finansiella instrument. Denna studie undersöker i första hand huruvida insynshandel på Aktietorget och Nordic Growth Market genererar abnormal avkastning samt om det föreligger en skillnad i resultat mellan dessa marknadsplatser. Det som ligger till grund för studien är insiders samtliga köp- och säljtransaktioner under 2005 för bolag noterade på Aktietorget och Nordic Growth Market. Studien är av kvantitativt slag och använder sig av marknadsmodellen för att beräkna förväntad och abnormal avkastning hos bolagen. Resultaten visar att det råder abnormal avkastning för både Aktietorget och Nordic Growth Market under den testade tidsperioden. Aktietorget visar att eventfönstret har en genomsnittlig abnormal avkastning om 2,93 % för köptransaktioner och 2,33 % för säljtransaktioner medan Nordic Growth Market har en genomsnittlig abnormal avkastning om 4,68 % för köptransaktioner och 2,19 % för säljtransaktioner.

• 1072.
Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
Stockholm University, Faculty of Science, Department of Meteorology . Stockholm University, Faculty of Science, Department of Meteorology . Stockholm University, Faculty of Science, Department of Meteorology . Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
Future response of temperature and precipitation to reduced aerosol emissions as compared with increased greenhouse gas concentrations2017In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 30, no 3, p. 939-954Article in journal (Refereed)

Experiments with a climate model (NorESM1) were performed to isolate the effects of aerosol particles and greenhouse gases on surface temperature and precipitation in simulations of future climate. The simulations show that by 2025-2049, a reduction of aerosol emissions from fossil fuels following a maximum technically feasible reduction (MFR) scenario could lead to a global and Arctic warming of 0.26 K and 0.84 K, respectively; as compared with a simulation with fixed aerosol emissions at the level of 2005. If fossil fuel emissions of aerosols follow a current legislation emissions (CLE) scenario, the NorESM1 model simulations yield a non-significant change in global and Arctic average surface temperature as compared with aerosol emissions fixed at year 2005. The corresponding greenhouse gas effect following the RCP4.5 emission scenario leads to a global and Arctic warming of 0.35 K and 0.94 K, respectively.

The model yields a marked annual average northward shift in the inter-tropical convergence zone with decreasing aerosol emissions and subsequent warming of the northern hemisphere. The shift is most pronounced in the MFR scenario but also visible in the CLE scenario. The modeled temperature response to a change in greenhouse gas concentrations is relatively symmetric between the hemispheres and there is no marked shift in the annual average position of the inter-tropical convergence zone. The strong reduction in aerosol emissions in MFR also leads to a net southward cross-hemispheric energy transport anomaly both in the atmosphere and ocean, and enhanced monsoon circulation in Southeast and East Asia causing an increase in precipitation over a large part of this region.

• 1073.
Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
Anthropogenic influence on climate through changes in aerosol emissions from air pollution and land use change2017Doctoral thesis, comprehensive summary (Other academic)

Particulate matter suspended in air (i.e. aerosol particles) exerts a substantial influence on the climate of our planet and is responsible for causing severe public health problems in many regions across the globe. Human activities have altered the natural and anthropogenic emissions of aerosol particles through direct emissions or indirectly by modifying natural sources. The climate effects of the latter have been largely overlooked. Humans have dramatically altered the land surface of the planet causing changes in natural aerosol emissions from vegetated areas. Regulation on anthropogenic and natural aerosol emissions have the potential to affect the climate on regional to global scales. Furthermore, the regional climate effects of aerosol particles could potentially be very different than the ones caused by other climate forcers (e.g. well mixed greenhouse gases). The main objective of this work was to investigate the climatic effects of land use and air pollution via aerosol changes.

Using numerical model simulations it was found that land use changes in the past millennium have likely caused a positive radiative forcing via aerosol climate interactions. The forcing is an order of magnitude smaller and has an opposite sign than the radiative forcing caused by direct aerosol emissions changes from other human activities. The results also indicate that future reductions of fossil fuel aerosols via air quality regulations may lead to an additional warming of the planet by mid-21st century and could also cause an important Arctic amplification of the warming. In addition, the mean position of the intertropical convergence zone and the Asian monsoon appear to be sensitive to aerosol emission reductions from air quality regulations. For these reasons, climate mitigation policies should take into consideration aerosol air pollution, which has not received sufficient attention in the past.

• 1074.
Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
Historical anthropogenic radiative forcing of changes in biogenic secondary organic aerosol2015Licentiate thesis, comprehensive summary (Other academic)

Human activities have lead to changes in the energy balance of the Earth and the global climate. Changes in atmospheric aerosols are the second largest contributor to climate change after greenhouse gases since 1750 A.D. Land-use practices and other environmental drivers have caused changes in the emission of biogenic volatile organic compounds (BVOCs) and secondary organic aerosol (SOA) well before 1750 A.D, possibly causing climate effects through aerosol-radiation and aerosol-cloud interactions. Two numerical emission models LPJ-GUESS and MEGAN were used to quantify the changes in aerosol forming BVOC emissions in the past millennium. A chemical transport model of the atmosphere (GEOS-Chem-TOMAS) was driven with those BVOC emissions to quantify the effects on radiation caused by millennial changes in SOA.

The specific objectives of this licentiate thesis are: 1) to understand what drove the changes in aerosol-forming BVOC emissions (i.e. isoprene, monoterpenes and sesquiterpenes) and to quantify these changes; 2) to calculate for the first time the combined historical aerosol direct and aerosol-cloud albedo effects on radiation from changing BVOC emissions through SOA formation; 3) to investigate how important the biological climate feedback associated to BVOC emissions and SOA formation is from a global climate perspective.

We find that global isoprene emissions decreased after 1800 A.D. by about 12% - 15%. This decrease was dominated by losses of natural vegetation, whereas monoterpene and sesquiterpene emissions increased by about 2% - 10%, driven mostly by rising surface air temperatures. From 1000 A.D. to 1800 A.D, isoprene, monoterpene and sesquiterpene emissions decline by 3% - 8% driven by both, natural vegetation losses, and the moderate global cooling between the medieval climate anomaly and the little ice age. The millennial reduction in BVOC emissions lead to a 0.5% to 2% reduction in climatically relevant aerosol particles (> 80 nm) and cause a direct radiative forcing between +0.02 W/m² and +0.07 W/m², and an indirect radiative forcing between -0.02 W/m² and +0.02 W/m². The suggested biological climate feedback seems to be too small to have observable consequences on the global climate in the recent past.

• 1075.
Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
Stockholm University, Faculty of Science, Department of Meteorology . Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
Global emissions of terpenoid VOCs from terrestrial vegetation in the last millennium2014In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 119, no 11, p. 6867-6885Article in journal (Refereed)

We investigated the millennial variability (1000 A.D.-2000 A.D.) of global biogenic volatile organic compound (BVOC) emissions by using two independent numerical models: The Model of Emissions of Gases and Aerosols from Nature (MEGAN), for isoprene, monoterpene, and sesquiterpene, and Lund-Potsdam-Jena-General Ecosystem Simulator (LPJ-GUESS), for isoprene and monoterpenes. We found the millennial trends of global isoprene emissions to be mostly affected by land cover and atmospheric carbon dioxide changes, whereas monoterpene and sesquiterpene emission trends were dominated by temperature change. Isoprene emissions declined substantially in regions with large and rapid land cover change. In addition, isoprene emission sensitivity to drought proved to have significant short-term global effects. By the end of the past millennium MEGAN isoprene emissions were 634 TgC yr-1 (13% and 19% less than during 1750-1850 and 1000-1200, respectively), and LPJ-GUESS emissions were 323 TgC yr-1(15% and 20% less than during 1750-1850 and 1000-1200, respectively). Monoterpene emissions were 89 TgC yr-1(10% and 6% higher than during 1750-1850 and 1000-1200, respectively) in MEGAN, and 24 TgC yr-1 (2% higher and 5% less than during 1750-1850 and 1000-1200, respectively) in LPJ-GUESS. MEGAN sesquiterpene emissions were 36 TgC yr-1(10% and 4% higher than during 1750-1850 and 1000-1200, respectively). Although both models capture similar emission trends, the magnitude of the emissions are different. This highlights the importance of building better constraints on VOC emissions from terrestrial vegetation.

• 1076.
Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
Stockholm University, Faculty of Science, Department of Meteorology . Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Linköping University, Sweden. Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Stockholm University, Faculty of Science, Department of Meteorology .
Amplification of Arctic warming by past air pollution reductions in Europe2016In: Nature Geoscience, ISSN 1752-0894, E-ISSN 1752-0908, Vol. 9, no 4, p. 277-+Article in journal (Refereed)

The Arctic region is warming considerably faster than the rest of the globe(1), with important consequences for the ecosystems(2) and human exploration of the region(3). However, the reasons behind this Arctic amplification are not entirely clear(4). As a result of measures to enhance air quality, anthropogenic emissions of particulate matter and its precursors have drastically decreased in parts of the Northern Hemisphere over the past three decades(5). Here we present simulations with an Earth system model with comprehensive aerosol physics and chemistry that show that the sulfate aerosol reductions in Europe since 1980 can potentially explain a significant fraction of Arctic warming over that period. Specifically, the Arctic region receives an additional 0.3Wm(-2) of energy, and warms by 0.5 degrees C on annual average in simulations with declining European sulfur emissions in line with historical observations, compared with a model simulation with fixed European emissions at 1980 levels. Arctic warming is amplified mainly in fall and winter, but the warming is initiated in summer by an increase in incoming solar radiation as well as an enhanced poleward oceanic and atmospheric heat transport. The simulated summertime energy surplus reduces sea-ice cover, which leads to a transfer of heat from the Arctic Ocean to the atmosphere. We conclude that air quality regulations in the Northern Hemisphere, the ocean and atmospheric circulation, and Arctic climate are inherently linked.

• 1077.
Stockholm University, Faculty of Humanities, Department of Spanish, Portuguese and Latin American Studies.
MERCOSUR SOM ETT NYTT REGIONALT BLOCK: Ett steg närmare en Sydamerikansk Union?2007Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis

Uppsatsen har till syfte att undersöka huruvida MERCOSUR är en aktör på den internationella arenan och om dess tilltagande utveckling kommer kunna bidra till ett ökat interregionalt samarbete. Uppsatsen ska uppnå syftet genom att svara på två frågeställningar: 1) Kan MERCOSUR definieras som en aktör på den internationella arenan? 2) Kan MERCOSUR ses som ett nytt regionalt block och därmed ingå i interregionala samarbeten?

Uppsatsen går igenom nya regionala blockens uppkomst och vad som skiljer dem åt från andra frihandels avtal. Uppsatsen är en komparativ analys som använder sig av två modeller för att svara på frågeställningarna. Den ena är Björn Hettnes dynamiska modell som beskriver en förändringsprocess. Den andra modellen består av fem kriterier, vilka definierats av Bretherton och Vogler och definierar ett aktörsbeteende. Denna typ av modell är, till skillnad från Hettnes, en statisk modell som används för att definiera grundläggande egenskaper. I samband med Bretherton och Voglers kriterier undersöks fundamentala begrepp, så som actorness och regioness, för att på underlätta analysen om huruvida MERCOSUR agerar som en aktör. För att kunna förstå uppkomsten och utvecklingen av regionala block undersöks hur EU skapades och uppkomsten av Europeiska värderingar samt en introduktion till regionala sammanslutningar i Latinamerika. EU är det äldsta regionala blocket vars gemensamma politik innefattar både ekonomiska och politiska mål. EU stödjer hela den regionala utvecklingen i Latin Amerika och dess interregionala politik bygger på dialog och samförstånd vilket gynnar sammanslutningarna i kontinenten. Speciellt har utvecklingen i MERCOSUR varit av intresse. MERCOSUR har blivit sedd som ett alternativ till det USA drivna projektet FTAA.

• 1078. Acosta-Michlik, L.
Stockholm University, interfaculty units, Stockholm Resilience Centre. Stockholm Environment Institute.
Application of fuzzy models to assess susceptibility to droughts from a socio-economic perspective2008In: Regional Environmental Change, Vol. 8, no 4, p. 151-160Article in journal (Refereed)
• 1079. Acquaviva, Viviana
Stockholm University, Faculty of Science, Department of Astronomy.
THE CURIOUS CASE OF Ly alpha EMITTERS: GROWING YOUNGER FROM z similar to 3 to z similar to 2?2012In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 751, no 2, article id L26Article in journal (Refereed)

Ly alpha emitting (LAE) galaxies are thought to be progenitors of present-day L* galaxies. Clustering analyses have suggested that LAEs at z similar to 3 might evolve into LAEs at z similar to 2, but it is unclear whether the physical nature of these galaxies is compatible with this hypothesis. Several groups have investigated the properties of LAEs using spectral energy distribution (SED) fitting, but direct comparison of their results is complicated by inconsistencies in the treatment of the data and in the assumptions made in modeling the stellar populations, which are degenerate with the effects of galaxy evolution. By using the same data analysis pipeline and SED fitting software on two stacked samples of LAEs at z = 3.1 and z = 2.1, and by eliminating several systematic uncertainties that might cause a discrepancy, we determine that the physical properties of these two samples of galaxies are dramatically different. LAEs at z = 3.1 are found to be old (age similar to 1 Gyr) and metal-poor (Z < 0.2 Z(circle dot)), while LAEs at z = 2.1 appear to be young (age similar to 50 Myr) and metal-rich (Z > Z(circle dot)). The difference in the observed stellar ages makes it very unlikely that z = 3.1 LAEs evolve directly into z = 2.1 LAEs. Larger samples of galaxies, studies of individual objects, and spectroscopic measurements of metallicity at these redshifts are needed to confirm this picture, which is difficult to reconcile with the effects of 1 Gyr of cosmological evolution.

• 1080.
University of California, Davis.
Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
Magnetostratigraphic and Cyclostratigraphic Records from Eocene-Miocene Sediments Cored in the Paleoequatorial Pacific: Initial Results from IODP Expedition 3202009Conference paper (Other academic)

Sediments from the paleoequatorial Pacific record the paleomagnetic field with high-fidelity and contain cyclic variations in chemical and physical properties that can be astronomically tuned, as has been shown from past Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) cruises, e.g., Legs 85, 138, 198, and 199. In an effort to fill gaps from past coring and to construct complete stratigraphic sections spanning the Cenozoic, Integrated Ocean Drilling Program (IODP) Expeditions 320 and 321 cored sediments along a Pacific Equatorial Age Transect (PEAT) earlier this year. A total of 23 holes at 8 Sites (Sites U1331 through U1338) were cored, recovering 6,141 m of sediment (Preliminary Reports are available at http://iodp.tamu.edu/publications/PR.html). Initial paleomagnetic results from Expedition 320 include measurements at 56,222 intervals along ~2000 split-core sections, as well as detailed progressive alternating field (AF) and thermal demagnetization of over 400 discrete samples (7 cm3 cubes). The cleaned paleomagnetic data were characterized by shallow inclinations, consistent with the sites being near the paleoequator, and by 180° alternations in declination downhole, reflecting magnetic polarity zones. The resulting magnetostratigraphies, which are used to develop initial age models for the drill sites, yield 803 dates ranging from 51.743 Ma (the base of Chron 23n.2n at Site 1331) to the present (Chron C1n; 0 to 0.783 Ma at Site U1335). In addition, 83 short polarity intervals were observed that might correspond to cryptochrons or geomagnetic excursions. We will discuss initial efforts to further resolve the PEAT magnetostratigraphies and to integrate them with bio-, chemo-, and cyclo- stratigraphies from the equatorial Pacific and elsewhere in order to improve and extend astronomical calibration of the geologic timescale.

• 1081.
Stockholm University, Faculty of Social Sciences, School of Business.
Stockholm University, Faculty of Social Sciences, School of Business. Stockholm University, Faculty of Social Sciences, School of Business.
Lojalitetsstudie över Skandiabanken: Månaderna efter Skandia Liv skandalen2004Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis

Denna uppsats handlar om lojalitet, banker, koncernkriser och varumärken. Hur vi lyckades blanda ihop alla dessa begrepp till en enda forskningsfråga är minst sagt intressant. När vi upptäckte att Skandia Liv krisen fick mer och mer uppmärksamhet i medierna övervägde vi möjligheten att Skandiabankens kunders lojalitet skulle påverkas. Ur detta föddes forskningsfrågan i uppsatsen: Hur har Skandiabankens kunders attityd gentemot sin bank påverkats i samband med Skandia Livs medieuppmärksammade kris?

• 1082.
Birkbeck, University of London, , Department of Computer Science and Information Systems.
Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
E-trade Facilitation in Ghana: a Capability Approach Perspective2014In: Electronic Journal of Information Systems in Developing Countries, ISSN 1681-4835, E-ISSN 1681-4835, Vol. 63, no 5, p. 1-13Article in journal (Refereed)
Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
ICT-based trade facilitation and the MDGs: a case study of a public–private partnership in Ghana2014In: ICTs and the Millennium Development Goals: a United Nations Perspective, Springer, 2014, no 2013, p. 223-235Chapter in book (Other academic)

The strategic and innovative deployment and use of information and communication technologies (ICT) is important to development and the attainment of the millennium development goals (MDGs). Previous studies have suggested that ICT-based trade facilitation promotes development through better integration into global markets. Through an interpretive case study, this chapter explores an ICTbased initiative to connect members of the trading community in Ghana on an electronic data interchange (EDI) platform. More specifi cally, it explored the contributions of the initiative to effi cient trade facilitation and discusses the broader mplications for achieving the MDGs in Ghana. The research confi rms that the initiative has improved operational effi ciency at Ghana’s ports and borders. Furthermore, it has enabled effi cient and reliable collection of duties and taxes. The findings reinforce the view that government support and private sector expertise and funding are important factors in ICT-based e-government solutions in developing countries. The chapter contends that ICT-based trade facilitation can make a significant contribution to the attainment of the MDGs in Ghana.

Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
IT Governance Practices in a Public Organization in Ghana2014In: International Journal of Innovation in the Digital Economy, ISSN 1947-8305, E-ISSN 1947-8313, Vol. 5, no 2, p. 14-23Article in journal (Refereed)

The strategic importance of information technology (IT) in today's organizations and dependence on IT to support e-government strategies has increased the interest in IT Governance (ITG) in public sector organizations. From this perspective, this paper examines ITG practices in a public organization in Ghana (that has a responsibility to mobilize revenue for national development) in order to gain an insight into IT governance structures, processes and relational mechanisms and understand how this contributes to adding value through IT. The findings have revealed that this public organization has a centralized approach to IT governance, with inadequate board involvement concerning how IT investments can bring value and improve organizational performance. Furthermore, there are no IT steering and strategy committees to oversee IT governance as best practice requires.

• 1085.
Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences. Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
Business-IT Alignment in Trade Facilitation: A Case Study2010In: Organizational, Business, and Technological Aspects of the Knowledge Society / [ed] Lytras, M.D.; Ordonez De Pablos, P.; Ziderman, A.; Roulstone, A.; Maurer, H.; Imber, J.B., Berlin Heidelberg: Springer-Verlag , 2010, Vol. 112, p. 146-Conference paper (Other academic)

In the information age, no organization can thrive without harnessing the power of IT. The effective deployment of IT to achieve business goals and gain competitive advantage requires the alignment of business and IT strategies of organizations. Using the Strategic Alignment Maturity model, this paper evaluates strategic alignment maturity of Customs Excise Preventive service, a frontline public organization charged with trade facilitation in Ghana. Strategic alignment maturity is at level 3; which implies the existence of an established process to leverage IT for efficiency and effectiveness. Efforts are required to strengthen alignment and fully harness the potential of IT to facilitate trade in Ghana.

Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. University of Gothenburg, Sweden.
N2-fixation, ammonium release and N-transfer to the microbial and classical food web within a plankton community2016In: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 10, no 2, p. 450-459Article in journal (Refereed)

We investigated the role of N2-fixation by the colony-forming cyanobacterium, Aphanizomenon spp., for the plankton community and N-budget of the N-limited Baltic Sea during summer by using stable isotope tracers combined with novel secondary ion mass spectrometry, conventional mass spectrometry and nutrient analysis. When incubated with 15N2Aphanizomenon spp. showed a strong 15N-enrichment implying substantial 15N2-fixation. Intriguingly, Aphanizomenon did not assimilate tracers of 15NH4+ from the surrounding water. These findings are in line with model calculations that confirmed a negligible N-source by diffusion-limited NH4+ fluxes to Aphanizomenon colonies at low bulk concentrations (<250 nm) as compared with N2-fixation within colonies. No N2-fixation was detected in autotrophic microorganisms <5 μm, which relied on NH4+uptake from the surrounding water. Aphanizomenon released about 50% of its newly fixed N2 as NH4+. However, NH4+ did not accumulate in the water but was transferred to heterotrophic and autotrophic microorganisms as well as to diatoms (Chaetoceros sp.) and copepods with a turnover time of ~5 h. We provide direct quantitative evidence that colony-formingAphanizomenon releases about half of its recently fixed N2 as NH4+, which is transferred to the prokaryotic and eukaryotic plankton forming the basis of the food web in the plankton community. Transfer of newly fixed nitrogen to diatoms and copepods furthermore implies a fast export to shallow sediments via fast-sinking fecal pellets and aggregates. Hence, N2-fixing colony-forming cyanobacteria can have profound impact on ecosystem productivity and biogeochemical processes at shorter time scales (hours to days) than previously thought.

• 1087.
Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
Early Resistance of Non-virulent Mycobacterial Infection in C57BL/6 Mice Is Associated With Rapid Up-Regulation of Antimicrobial Cathelicidin Camp2018In: Frontiers in Immunology, ISSN 1664-3224, E-ISSN 1664-3224, Vol. 9, article id 1939Article in journal (Refereed)

Early clearance of tuberculosis is the successful eradication of inhaled bacteria before the development of an adaptive immune response. We previously showed, by utilizing a non-virulent mycobacteria infection model, that C57BL/6 mice are more efficient than BALB/c in their control of bacterial growth in the lungs during the first weeks of the infection. Here, we assessed early (within 1-3 days) innate immune events locally in the lungs to identify factors that may contribute to the control of non-virulent mycobacterial burden. We confirmed that C57BL/6 mice are more resistant to infection compared with BALB/c after intranasal inoculation with mycobacterium. Transcriptomic analyses revealed a remarkably silent signature in C57BL/6 mice despite effective control of bacterial growth. In contrast, BALB/c mice up-regulated genes associated with neutrophil and myeloid cell chemotaxis and migration. Flow cytometry analyses corroborated the transcriptomic analyses and demonstrated influx of both neutrophil and myeloid cell populations in BALB/c mice, while these did not increase in C57BL/6 mice. We further detected increased release of TNF-alpha from BALB/c lung cells but limited release from C57BL/6-derived cells. However, C57BL/6 mice showed a marked early up-regulation of the Camp gene, encoding the cathelicidin CRAMP peptide, post-mycobacterial exposure. CRAMP (LL-37 in human) expression in the lungs was confirmed using immunofluorescence staining. Altogether, these findings show that C57BL/6 mice can clear the mycobacterial infection early and that this early control is associated with high CRAMP expression in the lungs without concomitant influx of immune cells. The role of CRAMP/LL-37 during mycobacterial infection may be relevant for novel protective strategies, and warrants further studies of human cohorts.

• 1088.
Stockholm University, Faculty of Social Sciences, Department of Human Geography.
Demokratisk planering och medborgardeltagande: En komparativ fallstudie av olika planeringsmodeller i översiktsplaneringen av Väsby Sjöstad i Upplands Väsby2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

Demokratisk planering och medborgardeltagande - En komparativ fallstudie av olika planeringsmodeller i översiktsplaneringen av Väsby Sjöstad i Upplands Väsby [Democratic planning and citizen participation - A comparative case study of different planning models used in the comprehensive planning of Väsby Sjöstad in Upplands Väsby]

Masteruppsats för masterexamen i samhällsplanering, 30 HP

Handledare: Peter Schmitt

Språk: Svenska

Uppsatsen syftar till att undersöka hur den demokratiska planeringsmodellen hanterar frågor gällande medborgerligt deltagande. Vem har makten att påverka och förändra de politiska beslut som planeringsmodellen vilar på? Uppsatsen undersöker utifrån denna övergripande fråga i fallstudieform planeringsprocessen för ett ambitiöst och kontroversiellt framtida bostadsområde i Upplands Väsby kallat Väsby Sjöstad. Den teoretiska ansatsen utgörs av maktbegreppet och dess kopplingar till rationalitet, starkt inspirerat av Michel Foucaults och Bent Flyvbjergs maktteorier. Den huvudsakliga metoden för undersökningen är en diskursanalys. Planeringsprocessen i fallet har genomgått distinkt olika faser och utmynnat i en charrette-inspirerad metod kallad community planning. Metoden medför att en konfliktfylld och låst planeringsprocess omvandlats till en inklusiv och kommunikativ sådan. Slutsatsen är att community planning med fördel kan användas för att ge medborgare en reell makt att påverka politiska beslut och planeringsresultat, men främst under tidiga planskeden.

Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Princeton University, USA.
Planck 2015 results X. Diffuse component separation: Foreground maps2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 594, article id A10Article in journal (Refereed)

Planck has mapped the microwave sky in temperature over nine frequency bands between 30 and 857 GHz and in polarization over seven frequency bands between 30 and 353 GHz in polarization. In this paper we consider the problem of diffuse astrophysical component separation, and process these maps within a Bayesian framework to derive an internally consistent set of full-sky astrophysical component maps. Component separation dedicated to cosmic microwave background (CMB) reconstruction is described in a companion paper. For the temperature analysis, we combine the Planck observations with the 9-yr Wilkinson Microwave Anisotropy Probe (WMAP) sky maps and the Haslam et al. 408 MHz map, to derive a joint model of CMB, synchrotron, free-free, spinning dust, CO, line emission in the 94 and 100 GHz channels, and thermal dust emission. Full-sky maps are provided for each component, with an angular resolution varying between 7: 5 and 1 degrees. Global parameters (monopoles, dipoles, relative calibration, and bandpass errors) are fitted jointly with the sky model, and best-fit values are tabulated. For polarization, the model includes CMB, synchrotron, and thermal dust emission. These models provide excellent fits to the observed data, with rms temperature residuals smaller than 4pK over 93% of the sky for all Planck frequencies up to 353 GHz, and fractional errors smaller than 1% in the remaining 7% of the sky. The main limitations of the temperature model at the lower frequencies are internal degeneracies among the spinning dust, free-free, and synchrotron components; additional observations from external low-frequency experiments will be essential to break these degeneracies. The main limitations of the temperature model at the higher frequencies are uncertainties in the 545 and 857 GHz calibration and zero-points. For polarization, the main outstanding issues are instrumental systematics in the 100-353 GHz bands on large angular scales in the form of temperature-to-polarization leakage, uncertainties in the analogue-to-digital conversion, and corrections for the very long time constant of the bolometer detectors, all of which are expected to improve in the near future.

Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Princeton University, USA.
Planck 2015 results IX. Diffuse component separation: CMB maps2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 594, article id A9Article in journal (Refereed)

We present foreground-reduced cosmic microwave background (CMB) maps derived from the full Planck data set in both temperature and polarization. Compared to the corresponding Planck 2013 temperature sky maps, the total data volume is larger by a factor of 3.2 for frequencies between 30 and 70 GHz, and by 1.9 for frequencies between 100 and 857 GHz. In addition, systematic errors in the forms of temperature-topolarization leakage, analogue-to-digital conversion uncertainties, and very long time constant errors have been dramatically reduced, to the extent that the cosmological polarization signal may now be robustly recovered on angular scales l greater than or similar to 40. On the very largest scales, instrumental systematic residuals are still non-negligible compared to the expected cosmological signal, and modes with l < 20 are accordingly suppressed in the current polarization maps by high-pass filtering. As in 2013, four different CMB component separation algorithms are applied to these observations, providing a measure of stability with respect to algorithmic and modelling choices. The resulting polarization maps have rms instrumental noise ranging between 0.21 and 0.27 mu K averaged over 55' pixels, and between 4.5 and 6.1 mu K averaged over 3.'4 pixels. The cosmological parameters derived from the analysis of temperature power spectra are in agreement at the 1 sigma level with the Planck 2015 likelihood. Unresolved mismatches between the noise properties of the data and simulations prevent a satisfactory description of the higher-order statistical properties of the polarization maps. Thus, the primary applications of these polarization maps are those that do not require massive simulations for accurate estimation of uncertainties, for instance estimation of cross-spectra and cross-correlations, or stacking analyses. However, the amplitude of primordial non-Gaussianity is consistent with zero within 2 sigma for all local, equilateral, and orthogonal configurations of the bispectrum, including for polarization E-modes. Moreover, excellent agreement is found regarding the lensing B-mode power spectrum, both internally among the various component separation codes and with the best-fit Planck 2015 Lambda cold dark matter model.

Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Princeton University, USA.
Planck intermediate results XLIII. Spectral energy distribution of dust in clusters of galaxies2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 596, article id A104Article in journal (Refereed)

Although infrared (IR) overall dust emission from clusters of galaxies has been statistically detected using data from the Infrared Astronomical Satellite (IRAS), it has not been possible to sample the spectral energy distribution (SED) of this emission over its peak, and thus to break the degeneracy between dust temperature and mass. By complementing the IRAS spectral coverage with Planck satellite data from 100 to 857 GHz, we provide new constraints on the IR spectrum of thermal dust emission in clusters of galaxies. We achieve this by using a stacking approach for a sample of several hundred objects from the Planck cluster sample. This procedure averages out fluctuations from the IR sky, allowing us to reach a significant detection of the faint cluster contribution. We also use the large frequency range probed by Planck, together with component-separation techniques, to remove the contamination from both cosmic microwave background anisotropies and the thermal Sunyaev-Zeldovich effect (tSZ) signal, which dominate at v <= 353 GHz. By excluding dominant spurious signals or systematic effects, averaged detections are reported at frequencies 353 GHz <= v <= 5000 GHz. We confirm the presence of dust in clusters of galaxies at low and intermediate redshifts, yielding an SED with a shape similar to that of the Milky Way. Planck's resolution does not allow us to investigate the detailed spatial distribution of this emission (e.g. whether it comes from intergalactic dust or simply the dust content of the cluster galaxies), but the radial distribution of the emission appears to follow that of the stacked SZ signal, and thus the extent of the clusters. The recovered SED allows us to constrain the dust mass responsible for the signal and its temperature.

Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Princeton University, USA.
Planck intermediate results XLII. Large-scale Galactic magnetic fields2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 596, article id A103Article in journal (Refereed)

Recent models for the large-scale Galactic magnetic fields in the literature have been largely constrained by synchrotron emission and Faraday rotation measures. We use three different but representative models to compare their predicted polarized synchrotron and dust emission with that measured by the Planck satellite. We first update these models to match the Planck synchrotron products using a common model for the cosmic-ray leptons. We discuss the impact on this analysis of the ongoing problems of component separation in the Planck microwave bands and of the uncertain cosmic-ray spectrum. In particular, the inferred degree of ordering in the magnetic fields is sensitive to these systematic uncertainties, and we further show the importance of considering the expected variations in the observables in addition to their mean morphology. We then compare the resulting simulated emission to the observed dust polarization and find that the dust predictions do not match the morphology in the Planck data but underpredict the dust polarization away from the plane. We modify one of the models to roughly match both observables at high latitudes by increasing the field ordering in the thin disc near the observer. Though this specific analysis is dependent on the component separation issues, we present the improved model as a proof of concept for how these studies can be advanced in future using complementary information from ongoing and planned observational projects.

Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Università La Sapienza, Italy. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Princeton University, USA.
Planck intermediate results XLVII. Planck constraints on reionization history2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 596, article id A108Article in journal (Refereed)

We investigate constraints on cosmic reionization extracted from the Planck cosmic microwave background (CMB) data. We combine the Planck CMB anisotropy data in temperature with the low-multipole polarization data to fit Lambda CDM models with various parameterizations of the reionization history. We obtain a Thomson optical depth tau = 0.058 +/- 0.012 for the commonly adopted instantaneous reionization model. This confirms, with data solely from CMB anisotropies, the low value suggested by combining Planck 2015 results with other data sets, and also reduces the uncertainties. We reconstruct the history of the ionization fraction using either a symmetric or an asymmetric model for the transition between the neutral and ionized phases. To determine better constraints on the duration of the reionization process, we also make use of measurements of the amplitude of the kinetic Sunyaev-Zeldovich (kSZ) effect using additional information from the high-resolution Atacama Cosmology Telescope and South Pole Telescope experiments. The average redshift at which reionization occurs is found to lie between z = 7.8 and 8.8, depending on the model of reionization adopted. Using kSZ constraints and a redshift-symmetric reionization model, we find an upper limit to the width of the reionization period of Delta z < 2.8. In all cases, we find that the Universe is ionized at less than the 10% level at redshifts above z similar or equal to 10. This suggests that an early onset of reionization is strongly disfavoured by the Planck data. We show that this result also reduces the tension between CMB-based analyses and constraints from other astrophysical sources.

Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Università La Sapienza, Italy. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Princeton University, USA.
Planck 2015 results I. Overview of products and scientific results2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 594, article id A1Article in journal (Refereed)

The European Space Agency's Planck satellite, which is dedicated to studying the early Universe and its subsequent evolution, was launched on 14 May 2009. It scanned the microwave and submillimetre sky continuously between 12 August 2009 and 23 October 2013. In February 2015, ESA and the Planck Collaboration released the second set of cosmology products based on data from the entire Planck mission, including both temperature and polarization, along with a set of scientific and technical papers and a web-based explanatory supplement. This paper gives an overview of the main characteristics of the data and the data products in the release, as well as the associated cosmological and astrophysical science results and papers. The data products include maps of the cosmic microwave background (CMB), the thermal Sunyaev-Zeldovich effect, diffuse foregrounds in temperature and polarization, catalogues of compact Galactic and extragalactic sources (including separate catalogues of Sunyaev-Zeldovich clusters and Galactic cold clumps), and extensive simulations of signals and noise used in assessing uncertainties and the performance of the analysis methods. The likelihood code used to assess cosmological models against the Planck data is described, along with a CMB lensing likelihood. Scientific results include cosmological parameters derived from CMB power spectra, gravitational lensing, and cluster counts, as well as constraints on inflation, non-Gaussianity, primordial magnetic fields, dark energy, and modified gravity, and new results on low-frequency Galactic foregrounds.

• 1095.
Stockholm University, Faculty of Social Sciences, Department of Human Geography.
Governing from Above: Solid Waste Management in Nigeria's New Capital City of Abuja2007Doctoral thesis, monograph (Other academic)

This doctoral dissertation examines how the symbolic character of a relocated capital city influences and intersects with local conditions to shape the governance structure and relations in service delivery. The focus is on Abuja, the new capital city of Nigeria, and the sector studied is solid waste management. Abuja was planned to avoid the numerous problems facing other Nigerian cities. Contrary to the intention of government and planners, the city now houses the fastest growing slum in the country. There are various possible explanations for these outcomes but this study pays particular attention to the conception of Abuja as a symbol of national unity.

The ‘good governance’ agenda is often promoted by the World Bank and donors as a way of handling the numerous challenges facing African governments, including service delivery. A major expectation of the agenda is that local governments manage the urban development process in conjunction with an array of institutions ranging from the private sector to community groups and households. An underlying notion is that of a minimalist national state. This is not the case in Abuja, where governance is conducted at higher levels and the municipal council remains largely invisible. This is manifested in solid waste management, where the municipal council has no jurisdiction over the sector. In addition, community groups and households play very minimal roles in the governance of services. Drawing on the concept of space and place, the study concludes that the types of institutions found and their roles and relations are shaped by the national function of the city and the local power relations.

The study draws on primary and secondary data. Interviews were conducted with state officials, community leaders, households and interest groups, such as the private sector. Secondary data were obtained from government documents, studies and newspaper reports.

• 1096.
Stockholm University, Faculty of Social Sciences, Department of Human Geography.
Urban imaginaries: funding mega infrastructure projects in Lagos, Nigeria2018In: GeoJournal, ISSN 0343-2521, E-ISSN 1572-9893, Vol. 83, no 2, p. 257-274Article in journal (Refereed)

In today’s globalized world, mega infrastructure projects have emerged as one of the most popular strategies for attracting private capital and repositioning cities on the competitive landscape. The Lagos Megacity Project (LMCP) was launched to address a longstanding infrastructure crisis and to reinvent Lagos as a modern megacity. Using the LMCP as a case study, the paper examined the challenges facing the funding of mega infrastructure projects. Special attention is given to how capital is mobilized, the kinds of alliances or networks found and what gets prioritized. The paper observed that the alliance formed between the federal, Lagos and Ogun state governments to mobilize public funds quickly unraveled largely due to disputes traceable to the apportioning of fiscal and political responsibilities and the distribution of functions between the different tiers of government. Under the LMCP, disputes emerged between the federal government and the Lagos State Government (LSG) over who was responsible for what. A history of opposition politics and a highly politicized resource allocation system further made cooperation between the two particularly difficult. Furthermore, the LMCP signalled a renewed drive by the LSG to attract private investments through public–private partnership. The paper noted a host of problems but crucially there is a preference for elite projects, a practice that is reinforcing socio-spatial exclusion and confirms the persistent inequalities that accompany neoliberal and modernist projects. At the broadest level, the paper points to how modernist projects are fractured or undermined by specific ideologies and practices.

• 1097.
Stockholm University, Faculty of Social Sciences, Department of Human Geography.
Dealing with Waste: Resource Recovery and Entrepreneurship in Informal Solid Waste Management in African Cities2017Collection (editor) (Other academic)

The scope of the problem of waste management in African cities continues to change across space and time in line with changing socio-economic, political and environmental conditions. Crucially, the failure of the formal systems has paved the way for the informal sector. The overall aim of the book is to capture the dynamism and complexity of Informal Sector Solid Waste Management (ISSWM). The main argument is that while the poverty reduction potential of ISSWM remains valid and is acknowledged; there are broader issues to consider.

• 1098.
Stockholm University, Faculty of Science.
On kloedenellids and cytherellids (Ostracoda Platycopa) from the Silurian of Gotland.1966Book (Other academic)
• 1099.
Stockholm College.
Die Ideologie des Rechts, 1: Ursprung und Grundlagen des Rechts1944Doctoral thesis, monograph (Other academic)
• 1100.
Stockholm University, Faculty of Social Sciences, Department of Education.
A Narratable Self as Addressed by Human Rights2017In: Policy Futures in Education, ISSN 1478-2103, E-ISSN 1478-2103, Vol. 15, no 3, p. 252-261Article in journal (Refereed)

The paper extends the critique in earlier research of human rights as exclusive of otherness and difference by introducing the work of Adriana Cavarero (2000) on a narratable self. Hence, the formation of human rights is thus about the relations between different narratable selves, not just Western ones. A narrative learning, drawing on Cavarero (2000), shifts the focus in human rights learning from learning about the other to exposing one’s life story narrative through relationality.

19202122232425 1051 - 1100 of 102039
Cite
Citation style
• apa
• ieee
• modern-language-association-8th-edition
• vancouver
• Other style
More styles
Language
• de-DE
• en-GB
• en-US
• fi-FI
• nn-NO
• nn-NB
• sv-SE
• Other locale
More languages
Output format
• html
• text
• asciidoc
• rtf