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  • 251. Abdullah, Ailin
    et al.
    Berglund, Jenny
    Stockholm University, Faculty of Humanities, Department of Humanities and Social Sciences Education.
    State Neutrality and Islamic Education in Sweden2018In: European Perspectives on Islamic education and Public Schooling / [ed] Jenny Berglund, Sheffield, UK: Equinox Publishing, 2018, p. 312-334Chapter in book (Refereed)
    Abstract [en]

    Public debate about Islam and Muslims often focuses on contradictions, conflicts, and contrasting value systems. Since 9/11, the bombings in Madrid and London and the recent rise of ISIS this debate has to a large extent included a fear that Muslim immigrants will be disloyal to their new Western countries, and thus requires increased surveillance and control. Conversely, others argue that Muslim populations in the West have wrongly suffered from the increasing intolerance and suspicion resulting from terrorist acts committed by a small number of radicals. Such voices point to a need to safeguard religious freedom and the right to equal treatment regardless of a group’s ethnic, cultural, linguistic, or religious background. In many European countries, these discussions have directed attention toward places of Islamic education such as Muslim schools, mosques, and Islamic organizations, focusing on the sometimes controversial manner in which they have been depicted in the media, public discourse, and, within Muslim communities themselves (Aslan 2009; Birt 2006). Religious education is both an essential and a challenging objective for minorities since the “transmission” of religious tradition to future generations is crucial to the survival of any religion. In Sweden as elsewhere in Europe many Muslim children and teenagers and even adults attend privately-run, extra-curricular Islamic classes. Some attend Islamic schools or are taught at home. Publically funded Islamic education options provided by the state are an emergent option in several European countries. These classes lie not only at the heart of debates over religious freedom, equal rights to education, and integration, but are also connected to matters of securitization and the state control of Islam. This paper will present an overview of publicly funded, mainly pre-university Islamic education in Sweden, a European Western secular Christian majority country with a Muslim minority population. Firstly, I will establish a definition of Islamic education and a description of the state funding of education and religion in general. Then, the paper will move on to describe different types of Islamic education that are available in Sweden.

  • 252. Abdullah, Omed Gh.
    et al.
    Tahir, Dana A.
    Kadir, K.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Kurdistan Institution for Strategic Studies and Scientific Research, Iraq.
    Optical and structural investigation of synthesized PVA/PbS nanocomposites2015In: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 26, no 9, p. 6939-6944Article in journal (Refereed)
    Abstract [en]

    Polymer nanocomposite based on polyvinyl alcohol (PVA) and lead sulfide (PbS) in the average radius of (1.88-2.23) nm, have been synthesized using the chemical reduction rote and solution casting technique for different concentrations of PbS. The characterization of the polymer nanocomposite films were carried out using UV-visible spectroscopy, SEM, and XRD. The effect of various concentration of PbS NP on the optical properties of the composite has been studied to understand the optimum conditions for the synthesis process. The nanocomposite film shows high UV and visible light absorptions in the wavelength range of (200-500) nm, which correspond to the characteristics of the PbS NPs. The significant decreasing trend of the direct allowed band gap of the nanocomposite was observed upon increasing the Pb source concentration, from (6.27 eV) for pure PVA to (2.34 eV) for 0.04 M PbS concentration, which is much higher than the energy gap of bulk PbS value (0.41 eV). The calculated values of the static refractive index of Cauchy dispersion model were in the range of (1.09-1.20). X-ray diffraction analysis confirmed the cubic nanocrystalline PbS phase formation.

  • 253.
    Abebaw, Tilahun
    Stockholm University, Faculty of Science, Department of Mathematics. Matematik.
    On the decomposition of D-modules over a hyperplane arrangement2007Licentiate thesis, monograph (Other academic)
  • 254.
    Abebaw, Tilahun
    et al.
    Stockholm University, Faculty of Science, Department of Mathematics.
    Bogvad, Rikard
    Stockholm University, Faculty of Science, Department of Mathematics.
    Decomposition of D-modules over a hyperplane arrangement in the plane2010In: Arkiv för matematik, ISSN 0004-2080, E-ISSN 1871-2487, Vol. 48, no 2, p. 211-229Article in journal (Refereed)
    Abstract [en]

    Let alpha(1), alpha(2),..., alpha(m) be linear forms defined on C-n and X = C-n\boolean OR(m)(i=1) V(alpha(i)), where V(alpha(i))={p is an element of C-n : alpha(i)(p)=0}. The coordinate ring O-X of X is a holonomic A(n)-module, where A(n) is the nth Weyl algebra and since holonomic A(n)-modules have finite length, O-X has finite length. We consider a "" twisted"" variant of this An- module which is also holonomic. Define M-alpha(beta) to be the free rank-1 C[x](alpha)-module on the generator alpha(beta) (thought of as a multivalued function), where alpha(beta)=alpha(beta 1)(1),..., alpha(beta m)(m) and the multi-index beta=(beta(1),...,beta(m))is an element of C-m. Our main result is the computation of the number of decomposition factors of M-alpha(beta) and their description when n-2.

  • 255.
    Abebaw, Tilahun
    et al.
    Stockholm University, Faculty of Science, Department of Mathematics. Addis Ababa University, Ethiopia.
    Bøgvad, Rikard
    Stockholm University, Faculty of Science, Department of Mathematics.
    Decomposition factors of D-modules on hyperplane configurations in general position2012In: Proceedings of the American Mathematical Society, ISSN 0002-9939, E-ISSN 1088-6826, Vol. 140, no 8, p. 2699-2711Article in journal (Refereed)
    Abstract [en]

    Let alpha(1), ... , alpha(m) be linear functions on C-n and X = C-n \ V(alpha), where alpha = Pi(m)(i=1) alpha(i) and V(alpha) = {p is an element of C-n : alpha(p) = 0}. The coordinate ring O-X = C[x](alpha) of X is a holonomic A(n)-module, where A(n) is the n-th Weyl algebra, and since holonomic A(n)-modules have finite length, O-X has finite length. We consider a twisted variant of this A(n)-module which is also holonomic. Define M-alpha(beta) to be the free rank 1 C[x](alpha)-module on the generator alpha(beta) (thought of as a multivalued function), where alpha(beta) = alpha(beta 1)(1) ... alpha(beta m)(m) and the multi-index beta = (beta(1), ... , beta(m)) is an element of C-m. It is straightforward to describe the decomposition factors of M-alpha(beta), when the linear functions alpha(1), ... , alpha(m) define a normal crossing hyperplane configuration, and we use this to give a sufficient criterion on beta for the irreducibility of M-alpha(beta), in terms of numerical data for a resolution of the singularities of V(alpha).

  • 256.
    Abebe, Mihret
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bacsik, Zoltan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Spherical and Porous Particles of Calcium Carbonate Synthesized with Food Friendly Polymer Additives2015In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 15, no 8, p. 3609-3616Article in journal (Refereed)
    Abstract [en]

    Porous calcium carbonate particles were synthesized by adding solutions of Ca2+ to solutions of CO32- containing polymeric additives. Under optimized conditions well-defined aggregates of the anhydrous polymorph vaterite formed. A typical sample of these micrometer-sized aggregates had: a pore volume of 0.1 cm(3)/g, a pore width of similar to 10 nm, and a specific surface area of similar to 25-30 m(2)/ g. Only one mixing Order (calcium to carbonate) allowed the formation of vaterite, which was ascribed to the buffering capacity and relatively high pH of the CO32- solution. Rapid addition of the calcium chloride solution and rapid stirring promoted the formation of vaterite, due to the high supersaturation levels achieved. With xanthan gum, porous and micrometer-sized vaterite aggregates could be synthesized over a wide range of synthetic conditions. For the Other food grade polymers, hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), and sodium carboxyl methylcellulose, several intensive and extensive synthetic parameters had to be optimized to obtain pure vaterite and porous aggregates. HPMC and MC allowed well-defined spherical micrometer-sited particles to form. We expect that these spherical and porous particles of vaterite could be relevant to model studies as well as a controlled delivery of particularly large molecules.

  • 257.
    Abedi-Valugerdi, Manuchehr
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Mercury and silver induce B cell activation and anti-nucleolar autoantibody production in outbred mouse stocks: are environmental factors more important than the susceptibility genes in connection with autoimmunity?2009In: Clinical and Experimental Immunology, ISSN 0009-9104, E-ISSN 1365-2249, Vol. 155, no 1, p. 117-124Article in journal (Refereed)
    Abstract [en]

    Environmental and predisposing genetic factors are known to play a crucial role in the development of systemic autoimmune diseases. With respect to the role of environmental factors, it is not known how and to what extent they contribute to the initiation and exacerbation of systemic autoimmunity. In the present study, I considered this issue and asked if environmental factors can induce autoimmunity in the absence of specific susceptible genes. The development of genetically controlled mercury- and silver-induced B cell activation and anti-nucleolar autoantibodies (ANolA) production in genetically heterozygous outbred Institute of Cancer Research (ICR), Naval Medical Research Institute (NMRI) and Black Swiss mouse stocks were analysed. Four weeks of treatment with both mercury and silver induced a strong B cell activation characterized by increased numbers of splenic antibody-secreting cells of at least one or more immunoglobulin (Ig) isotype(s) in all treated stocks. The three stocks also exhibited a marked increase in the serum IgE levels in response to mercury, but not silver. More importantly, in response to mercury a large numbers of ICR (88%), NMRI (96%) and Black Swiss (100%) mice produced different levels of IgG1 and IgG2a ANolA (a characteristic which is linked strictly to the H-2 genes). Similarly, but at lower magnitudes, treatment with silver also induced the production of IgG1 and IgG2a ANolA in 60% of ICR, 75% of NMRI and 100% of Black Swiss mice. Thus, the findings of this study suggest that long-term exposure to certain environmental factors can activate the immune system to produce autoimmunity per se, without requiring specific susceptible genes.

  • 258. Abedi-Valugerdi, Manuchehr
    et al.
    Hansson, Monika
    Stockholm University, Faculty of Science, Wenner-Gren Institute for Experimental Biology.
    Möller, Göran
    Genetic control of resistance to mercury-induced immune/autoimmune activation2001In: Scandinavian Journal of Immunology, Vol. 54, no Jul-Aug, p. 190-197Article in journal (Refereed)
  • 259. Abel, Sebastian
    et al.
    Nybom, Inna
    Maenpaa, Kimmo
    Hale, Sarah E.
    Cornelissen, Gerard
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Norwegian Geotechnical Institute, Norway; Norwegian University of Life Sciences, Norway.
    Akkanen, Jarkko
    Mixing and capping techniques for activated carbon based sediment remediation Efficiency and adverse effects for Lumbriculus variegatus2017In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 114, p. 104-112Article in journal (Refereed)
    Abstract [en]

    Activated carbon (AC) has been proven to be highly effective for the in-situ remediation of sediments contaminated with a wide range of hydrophobic organic contaminants (HOCs). However, adverse biological effects, especially to benthic organisms, can accompany this promising remediation potential. In this study, we compare both the remediation potential and the biological effects of several AC materials for two application methods: mixing with sediment (MIX) at doses of 0.1 and 1.0% based on sediment dw and thin layer capping (TLC) with 0.6 and 1.2 kg AC/m(2). Significant dose dependent reductions in PCB bioaccumulation in Lumbriculus variegatus of 35-93% in MIX treatments were observed. Contaminant uptake in TLC treatments was reduced by up to 78% and differences between the two applied doses were small. Correspondingly, significant adverse effects were observed for L. variegatus whenever AC was present in the sediment. The lowest application dose of 0.1% AC in the MIX system reduced L variegatus growth, and 1.0% AC led to a net loss of organism biomass. All TLC treatments let to a loss of biomass in the test organism. Furthermore, mortality was observed with 1.2 kg ACim(2) doses of pure AC for the TLC treatment. The addition of clay (Kaolinite) to the TLC treatments prevented mortality, but did not decrease the loss in biomass. While TLC treatments pose a less laborious alternative for AC amendments in the field, the results of this study show that it has lower remediation potential and could be more harmful to the benthic fauna.

  • 260.
    Abel, Ulf
    Stockholm University.
    Carl Milles: form, idé, medaljkonst1980Doctoral thesis, monograph (Other academic)
  • 261.
    Abelein, Axel
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Modulation of Alzheimer's amyloid β peptide self-assembly: Insights into molecular mechanisms of peptide aggregation associated with Alzheimer's disease2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Misfolding of proteins and peptides is closely linked to several neurodegenerative disorders, among them Alzheimer's disease (AD), the most prominent example of brain diseases. The self-assembly of the amyloid β peptide (Aβ) into amyloid fibrils is one histologic hallmark of AD. A detailed knowledge about the underlying mechanism(s) of Aβ aggregation is crucial for advances toward a fundamental understanding of the disease, which may promote the search for and design of efficient therapeutics. The work presented in this thesis deals with modulation of the aggregation process by various compounds, i.e. small organic molecules (e.g. lacmoid and Congo red), surfactants and metal ions. These results provide insight into the molecular mechanism of modulator interactions and interference with Aβ and its aggregation pathways. Applying a combination of kinetic and dynamic studies as well as structural investigations we characterized the molecular interactions between Aβ and aggregation modulators in terms of microscopic rate constants, conformational preferences and thermodynamics. An important conclusion is that these modulators form highly dynamic complexes with Aβ, with life-times on the timescale of milliseconds. Despite the similar exchange dynamics, the effect on peptide aggregation is modulator-specific and fibril formation can be accelerated, retarded or inhibited by their interactions. In summary, Aβ self-assembly is governed by microscopic kinetic and dynamic processes that can be altered by aggregation modulators. Further elucidation of these mechanisms is beneficial for the understanding and therapeutic intervention of amyloid diseases.

  • 262.
    Abelein, Axel
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Modulation of amyloid β peptide self-assembly: Aggregation mechanisms associated with Alzheimer's disease2013Licentiate thesis, comprehensive summary (Other academic)
  • 263.
    Abelein, Axel
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Abrahams, Jan Pieter
    Danielsson, Jens
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Gräslund, Astrid
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Jarvet, Juri
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. National Institute of Chemical Physics and Biophysics, Estonia.
    Luo, Jinghui
    Tiiman, Ann
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Wärmländer, Sebastian K. T. S.
    The hairpin conformation of the amyloid beta peptide is an important structural motif along the aggregation pathway2014In: Journal of Biological Inorganic Chemistry, ISSN 0949-8257, E-ISSN 1432-1327, Vol. 19, no 4-5, p. 623-634Article, review/survey (Refereed)
    Abstract [en]

    The amyloid beta (A beta) peptides are 39-42 residue-long peptides found in the senile plaques in the brains of Alzheimer's disease (AD) patients. These peptides self-aggregate in aqueous solution, going from soluble and mainly unstructured monomers to insoluble ordered fibrils. The aggregation process(es) are strongly influenced by environmental conditions. Several lines of evidence indicate that the neurotoxic species are the intermediate oligomeric states appearing along the aggregation pathways. This minireview summarizes recent findings, mainly based on solution and solid-state NMR experiments and electron microscopy, which investigate the molecular structures and characteristics of the A beta peptides at different stages along the aggregation pathways. We conclude that a hairpin-like conformation constitutes a common motif for the A beta peptides in most of the described structures. There are certain variations in different hairpin conformations, for example regarding H-bonding partners, which could be one reason for the molecular heterogeneity observed in the aggregated systems. Interacting hairpins are the building blocks of the insoluble fibrils, again with variations in how hairpins are organized in the cross-section of the fibril, perpendicular to the fibril axis. The secondary structure propensities can be seen already in peptide monomers in solution. Unfortunately, detailed structural information about the intermediate oligomeric states is presently not available. In the review, special attention is given to metal ion interactions, particularly the binding constants and ligand structures of A beta complexes with Cu(II) and Zn(II), since these ions affect the aggregation process(es) and are considered to be involved in the molecular mechanisms underlying AD pathology.

  • 264.
    Abelein, Axel
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Bolognesi, Benedetta
    Dobson, Christopher M.
    Gräslund, Astrid
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Lendel, Christofer
    Hydrophobicity and conformational change as mechanistic determinants for nonspecific modulators of amyloid β self-assembly2012In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 51, no 1, p. 126-137Article in journal (Refereed)
    Abstract [en]

    The link between many neurodegenerative disorders, including Alzheimer's and Parkinson's diseases, and the aberrant folding and aggregation of proteins has prompted a comprehensive search for small organic molecules that have the potential to inhibit such processes. Although many compounds have been reported to affect the formation of amyloid fibrils and/or other types of protein aggregates, the mechanisms by which they act are not well understood. A large number of compounds appear to act in a nonspecific way affecting several different amyloidogenic proteins. We describe here a detailed study of the mechanism of action of one representative compound, lacmoid, in the context of the inhibition of the aggregation of the amyloid β-peptide (Aβ) associated with Alzheimer's disease. We show that lacmoid binds Aβ(1-40) in a surfactant-like manner and counteracts the formation of all types of Aβ(1-40) and Aβ(1-42) aggregates. On the basis of these and previous findings, we are able to rationalize the molecular mechanisms of action of nonspecific modulators of protein self-assembly in terms of hydrophobic attraction and the conformational preferences of the polypeptide.

  • 265.
    Abelein, Axel
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Gräslund, Astrid
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Danielsson, Jens
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    The zinc ion – a minimal chaperone mimicking agent forretardation of amyloid β peptide fibril formationManuscript (preprint) (Other academic)
  • 266.
    Abelein, Axel
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Gräslund, Astrid
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Danielsson, Jens
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Zinc as chaperone-mimicking agent for retardation of amyloid beta peptide fibril formation2015In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 112, no 17, p. 5407-5412Article in journal (Refereed)
    Abstract [en]

    Metal ions have emerged to play a key role in the aggregation process of amyloid beta (A beta) peptide that is closely related to the pathogenesis of Alzheimer's disease. A detailed understanding of the underlying mechanistic process of peptide-metal interactions, however, has been challenging to obtain. By applying a combination of NMR relaxation dispersion and fluorescence kinetics methods we have investigated quantitatively the thermodynamic A beta-Zn2+ binding features as well as how Zn2+ modulates the nucleation mechanism of the aggregation process. Our results show that, under near-physiological conditions, substoichiometric amounts of Zn2+ effectively retard the generation of amyloid fibrils. A global kinetic profile analysis reveals that in the absence of zinc A beta(40) aggregation is driven by a monomer-dependent secondary nucleation process in addition to fibril-end elongation. In the presence of Zn2+, the elongation rate is reduced, resulting in reduction of the aggregation rate, but not a complete inhibition of amyloid formation. We show that Zn2+ transiently binds to residues in the N terminus of the monomeric peptide. A thermodynamic analysis supports a model where the N terminus is folded around the Zn2+ ion, forming a marginally stable, short-lived folded A beta(40) species. This conformation is highly dynamic and only a few percent of the peptide molecules adopt this structure at any given time point. Our findings suggest that the folded A beta(40)-Zn2+ complex modulates the fibril ends, where elongation takes place, which efficiently retards fibril formation. In this conceptual framework we propose that zinc adopts the role of a minimal antiaggregation chaperone for A beta(40).

  • 267.
    Abelein, Axel
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Jarvet, Jüri
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. The National Institute of Chemical Physics and Biophysics, Estonia.
    Barth, Andreas
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Gräslund, Astrid
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Danielsson, Jens
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Ionic Strength Modulation of the Free Energy Landscape of A beta(40) Peptide Fibril Formation2016In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, no 21, p. 6893-6902Article in journal (Refereed)
    Abstract [en]

    Protein misfolding and formation of cross-beta structured amyloid fibrils are linked to, many neurodegenerative disorders. Although recently developed,quantitative approaches have started to reveal the molecular nature of self-assembly and fibril formation of proteins and peptides, it is yet unclear how these self-organization events are precisely modulated by microenvironmental factors, which are known to strongly affect the macroscopic aggregation properties. Here, we characterize the explicit effect of ionic strength on the microscopic aggregation rates of amyloid beta peptide (A beta 40) self-association, implicated in Alzheimer's disease. We found that physiological ionic strength accelerates A beta 40 aggregation kinetics by promoting surface-catalyzed secondary nucleation reactions. This promoted catalytic effect can be assigned to shielding of electrostatic repulsion between Monomers on the fibril surface or between the fibril surface itself and monomeric peptides. Furthermore, we observe the formation of two different beta-structured states with =similar but distinct spectroscopic features, which can be assigned to an off-pathway immature state (F-beta*) and a mature stable State (F-beta), where salt favors formation of the F-beta fibril morphology. Addition of salt to preformed F-beta* accelerates transition to F-beta, underlining the dynamic nature of A beta 40 fibrils in solution. On the basis of,these results we suggest a model where salt decreases the free-energy barrier for A beta 40 folding to the F-beta state, favoring the buildup of the mature fibril morphology while omitting competing, energetically less favorable structural states.

  • 268.
    Abelein, Axel
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Kaspersen, Jørn Døvling
    Nielsen, Søren Bang
    Jensen, Grethe Vestergaard
    Christiansen, Gunna
    Pedersen, Jan Skov
    Danielsson, Jens
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Otzen, Daniel E.
    Gräslund, Astrid
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Formation of dynamic soluble surfactant-induced amyloid β peptide aggregation intermediates2013In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 288, no 32, p. 23518-23528Article in journal (Refereed)
    Abstract [en]

    Intermediate amyloidogenic states along the amyloid β peptide (Aβ) aggregation pathway have been shown to be linked to neurotoxicity. To shed more light on the different structures that may arise during Aβ aggregation, we here investigate surfactant-induced Aβ aggregation. This process leads to co-aggregates featuring a β-structure motif that is characteristic for mature amyloid-like structures. Surfactants induce secondary structure in Aβ in a concentration-dependent manner, from predominantly random coil at low surfactant concentration, via β-structure to the fully formed α-helical state at high surfactant concentration. The β-rich state is the most aggregation-prone as monitored by thioflavin T fluorescence. Small angle x-ray scattering reveals initial globular structures of surfactant-Aβ co-aggregated oligomers and formation of elongated fibrils during a slow aggregation process. Alongside this slow (minutes to hours time scale) fibrillation process, much faster dynamic exchange (k(ex) ∼1100 s(-1)) takes place between free and co-aggregate-bound peptide. The two hydrophobic segments of the peptide are directly involved in the chemical exchange and interact with the hydrophobic part of the co-aggregates. Our findings suggest a model for surfactant-induced aggregation where free peptide and surfactant initially co-aggregate to dynamic globular oligomers and eventually form elongated fibrils. When interacting with β-structure promoting substances, such as surfactants, Aβ is kinetically driven toward an aggregation-prone state.

  • 269.
    Abelein, Axel
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Lang, Lisa
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Lendel, Christofer
    Gräslund, Astrid
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Danielsson, Jens
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Corrigendum to “Transient small molecule interactions kinetically modulate amyloid β peptide self-assembly” [FEBS Lett. 586 (2012) 3991–3995]2013In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 587, no 9, p. 1452-1452Article in journal (Other academic)
  • 270.
    Abelein, Axel
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Lang, Lisa
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Lendel, Christofer
    Gräslund, Astrid
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Danielsson, Jens
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Transient small molecule interactions kinetically modulate amyloid beta peptide self-assembly2012In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 586, no 22, p. 3991-3995Article in journal (Refereed)
    Abstract [en]

    Small organic molecules, like Congo red and lacmoid, have been shown to modulate the self-assembly of the amyloid beta peptide (A beta). Here, we show that A beta forms NMR invisible non-toxic co-aggregates together with lacmoid as well as Congo red. We find that the interaction involves two distinct kinetic processes and at every given time point only a small fraction of A beta is in the co-aggregate. These weak transient interactions kinetically redirect the aggregation prone A beta from self-assembling into amyloid fibrils. These findings suggest that even such weak binders might be effective as therapeutics against pathogenic protein aggregation.

  • 271. Abelin, Åsa
    et al.
    Zetterholm, Elisabeth
    Stockholm University, Faculty of Humanities, Department of Language Education.
    Spanish accented Swedish – when the neighbor becomes a fir-tree2019In: Comunicación Social: Lingüística, Medios Masivos, Arte, Etnología, Folclor y otras ciencias afines / [ed] María Rosa Álvarez Silva, Alex Muñoz Alvarado, Leonel Ruiz Miyares, Santiago de Cuba: Ediciones Centro de Lingüística Aplicada , 2019Conference paper (Refereed)
  • 272. Abellán, F. J.
    et al.
    Indebetouw, R.
    Marcaide, J. M.
    Gabler, M.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Spyromilio, J.
    Burrows, D. N.
    Chevalier, R.
    Cigan, P.
    Gaensler, B. M.
    Gomez, H. L.
    Janka, H. -Th.
    Kirshner, R.
    Larsson, J.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Matsuura, M.
    McCray, R.
    Ng, C. -Y.
    Park, S.
    Roche, P.
    Staveley-Smith, L.
    van Loon, J. Th.
    Wheeler, J. C.
    Woosley, S. E.
    Very Deep inside the SN 1987A Core Ejecta: Molecular Structures Seen in 3D2017In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 842, no 2, article id L24Article in journal (Refereed)
    Abstract [en]

    Most massive stars end their lives in core-collapse supernova explosions and enrich the interstellar medium with explosively nucleosynthesized elements. Following core collapse, the explosion is subject to instabilities as the shock propagates outward through the progenitor star. Observations of the composition and structure of the innermost regions of a core-collapse supernova provide a direct probe of the instabilities and nucleosynthetic products. SN 1987A in the Large Magellanic Cloud is one of very few supernovae for which the inner ejecta can be spatially resolved but are not yet strongly affected by interaction with the surroundings. Our observations of SN 1987A with the Atacama Large Millimeter/submillimeter Array are of the highest resolution to date and reveal the detailed morphology of cold molecular gas in the innermost regions of the remnant. The 3D distributions of carbon and silicon monoxide (CO and SiO) emission differ, but both have a central deficit, or torus-like distribution, possibly a result of radioactive heating during the first weeks (nickel heating). The size scales of the clumpy distribution are compared quantitatively to models, demonstrating how progenitor and explosion physics can be constrained.

  • 273. Abel-Ollo, K.
    et al.
    Rahu, M.
    Rajaleid, K.
    Stockholm University, Faculty of Social Sciences, Centre for Health Equity Studies (CHESS).
    Talu, A.
    Ruutel, K.
    Platt, L.
    Bobrova, N.
    Rhodes, T.
    Uuskula, A.
    Knowledge of HIV serostatus and risk behaviour among injecting drug users in Estonia2009In: AIDS Care, ISSN 0954-0121, E-ISSN 1360-0451, Vol. 21, no 7, p. 851-857Article in journal (Refereed)
    Abstract [en]

    We used the findings from two, cross-sectional studies of HIV serostatus and risk behaviours to assess the effects of knowledge of HIV serostatus and risk behaviours (relating to sex and injection drug use) among injecting drug users (IDUs). Respondent-driven sampling was used simultaneously at two sites in Estonia (the capital Tallinn, and the second-largest city of Ida-Virumaa County, Kohtla-Järve). The research tool was an interviewer-administered survey. Biological samples were collected for HIV testing. Participants were categorised into three groups based on HIV testing results and self-report on HIV serostatus: HIV-negative (n=133); HIV-positive unaware of their serostatus (n=75); and HIV-positive aware of their serostatus (n=168). In total, 65% of the participants tested positive for HIV. Of those 69% were aware of their positive serostatus. HIV-positive IDUs aware of their serostatus exhibited more risk behaviours than their HIV-positive counterparts unaware of their serostatus or HIV-negative IDUs. Effective prevention of HIV among IDUs should therefore, include programmes to reduce high-risk sexual and drug use behaviours at the public health scale and enhanced prevention efforts focusing on HIV-infected individuals.

  • 274. Aben, Ralf C. H.
    et al.
    Barros, Nathan
    van Donk, Ellen
    Frenken, Thijs
    Hilt, Sabine
    Kazanjian, Garabet
    Lamers, Leon P. M.
    Peeters, Edwin T. H. M.
    Roelofs, Jan G. M.
    de Senerpont Domis, Lisette N.
    Stephan, Susanne
    Velthuis, Mandy
    Van de Waal, Dedmer B.
    Wik, Martin
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Thornton, Brett F.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Wilkinson, Jeremy
    DelSontro, Tonya
    Kosten, Sarian
    Cross continental increase in methane ebullition under climate change2017In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, article id 1682Article in journal (Refereed)
    Abstract [en]

    Methane (CH4) strongly contributes to observed global warming. As natural CH4 emissions mainly originate from wet ecosystems, it is important to unravel how climate change may affect these emissions. This is especially true for ebullition (bubble flux from sediments), a pathway that has long been underestimated but generally dominates emissions. Here we show a remarkably strong relationship between CH4 ebullition and temperature across a wide range of freshwater ecosystems on different continents using multi-seasonal CH4 ebullition data from the literature. As these temperature-ebullition relationships may have been affected by seasonal variation in organic matter availability, we also conducted a controlled year-round mesocosm experiment. Here 4 degrees C warming led to 51% higher total annual CH4 ebullition, while diffusion was not affected. Our combined findings suggest that global warming will strongly enhance freshwater CH4 emissions through a disproportional increase in ebullition (6-20% per 1 degrees C increase), contributing to global warming.

  • 275.
    Abens, Jānis
    Stockholm University.
    On the neurohormonal peptides NPY and VIP and their receptors1988Doctoral thesis, comprehensive summary (Other academic)
  • 276.
    Abergel, D. S. L.
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita). KTH Royal Institute of Technology, Sweden.
    Excitonic condensation in spatially separated one-dimensional systems2015In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 106, no 21, article id 213103Article in journal (Refereed)
    Abstract [en]

    We show theoretically that excitons can form from spatially separated one-dimensional ground state populations of electrons and holes, and that the resulting excitons can form a quasicondensate. We describe a mean-field Bardeen-Cooper-Schrieffer theory in the low carrier density regime and then focus on the core-shell nanowire giving estimates of the size of the excitonic gap for InAs/GaSb wires and as a function of all the experimentally relevant parameters. We find that optimal conditions for pairing include small overlap of the electron and hole bands, large effective mass of the carriers, and low dielectric constant of the surrounding media. Therefore, one-dimensional systems provide an attractive platform for the experimental detection of excitonic quasicondensation in zero magnetic field.

  • 277.
    Abergel, David S. L.
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Robustness of topologically protected transport in graphene-boron nitride lateral heterostructures2017In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 29, no 7, article id 075303Article in journal (Refereed)
    Abstract [en]

    Previously, graphene nanoribbons set in lateral heterostructures with hexagonal boron nitride were predicted to support topologically protected states at low energy. We investigate how robust the transport properties of these states are against lattice disorder. We find that forms of disorder that do not couple the two valleys of the zigzag graphene nanoribbon do not impact the transport properties at low bias, indicating that these lateral heterostructures are very promising candidates for chip-scale conducting interconnects. Forms of disorder that do couple the two valleys, such as vacancies in the graphene ribbon, or substantial inclusions of armchair edges at the graphene-hexagonal boron nitride interface will negatively affect the transport. However, these forms of disorder are not commonly seen in current experiments.

  • 278.
    Abergel, David S. L.
    et al.
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Edge, Jonathan M.
    Balatsky, Alexander V.
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Los Alamos National Laboratory, USA.
    The role of spin-orbit coupling in topologically protected interface states in Dirac materials2014In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 16, p. 065012-Article in journal (Refereed)
    Abstract [en]

    We highlight the fact that two-dimensional (2D) materials with Dirac-like low energy band structures and spin-orbit coupling (SOC) will produce linearly dispersing topologically protected Jackiw-Rebbi modes at interfaces where the Dirac mass changes sign. These modes may support persistent spin or valley currents parallel to the interface, and the exact arrangement of such topologically protected currents depends crucially on the details of the SOC in the material. As examples, we discuss buckled 2D hexagonal lattices such as silicene or germanene, and transition metal dichalcogenides such as MoS2.

  • 279.
    Abergel, David S. L.
    et al.
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Mucha-Kruczynski, Marcin
    Infrared absorption of closely aligned heterostructures of monolayer and bilayer graphene with hexagonal boron nitride2015In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 92, no 11, article id 115430Article in journal (Refereed)
    Abstract [en]

    We model optical absorption of monolayer and bilayer graphene on hexagonal boron nitride for the case of closely aligned crystal lattices. We show that perturbations with different spatial symmetry can lead to similar absorption spectra. We suggest that a study of the absorption spectra as a function of the doping for an almost completely full first miniband is necessary to extract meaningful information about the moire characteristics from optical absorption measurements and to distinguish between various theoretical proposals for the physically realistic interaction. Also, for bilayer graphene, the ability to compare spectra for the opposite signs of electric-field-induced interlayer asymmetry might provide additional information about the moire parameters.

  • 280. Abernethy, K. E.
    et al.
    Bodin, Örjan
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Olsson, Per
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Hilly, Z.
    Schwarz, A.
    Two steps forward, two steps back: The role of innovation in transforming towards community-based marine resource management in Solomon Islands2014In: Global Environmental Change, ISSN 0959-3780, E-ISSN 1872-9495, Vol. 28, p. 309-321Article in journal (Refereed)
    Abstract [en]

    In many coastal nations, community-based arrangements for marine resource management (CBRM) are promoted by government, advocated for by non-government actors, and are seen by both as one of the most promising options to achieve sustainable use and secure inshore fisheries and aquatic resources. Although there is an abundant literature on what makes CBRM effective, is it less clear how CBRM is introduced or develops as an idea in a community, and the process of how the idea leads to the adoption of a new resource management approach with supporting institutions. Here we aim to address this gap by applying an explicit process-based approach drawing on innovation history methodology by mapping and analysing the initiation and emergence of CBRM in five fishing-dependent communities in Solomon Islands. We use insights from the literatures on diffusion of innovation and transformability to define phases of the process and help guide the inductive analysis of qualitative data. We show the CBRM institutionalisation processes were non-linear, required specific strategies to move from one phase to the next, and key elements facilitated or hindered movement. Building active support for CBRM within communities depended on the types of events that happened at the beginning of the process and actions taken to sustain this. Matching CBRM to known resource management ideas or other social problems in the community, developing legitimate institutions and decision-making processes, strong continual interactions between key actors and the rest of the community (not necessarily NGO actors), and community members witnessing benefits of CBRM, all contributed to the emergence and diffusion of CBRM in the communities, and helped to overcome barriers to transformative change.

  • 281. Abhiman, Saraswathi
    et al.
    Daub, Carsten O
    Sonnhammer, Erik L L
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Prediction of function divergence in protein families using the substitution rate variation parameter alpha.2006In: Mol Biol Evol, ISSN 0737-4038, Vol. 23, no 7, p. 1406-13Article in journal (Refereed)
  • 282. Abhiman, Saraswathi
    et al.
    Sonnhammer, Erik L L
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Large-scale prediction of function shift in protein families with a focus on enzymatic function.2005In: Proteins, ISSN 1097-0134, Vol. 60, no 4, p. 758-68Article in journal (Refereed)
  • 283.
    Abiala, Kristina
    Stockholm University, Faculty of Social Sciences, Department of Sociology.
    Säljande samspel: en sociologisk studie av privat servicearbete2000Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Interaction between people can be seen as a distinctive feature of 'post-industrial society'. In this study I investigate some of the conditions for this encounter in private service work in Sweden. I start by discussing some important concepts: service, service encounter and emotional labour. Three parties in an interactional triangle can be perceived: the service enterprise, the service worker and the customer.

    The service encounter is embedded in organisational frames. Recruiting for social competence and training for selling interaction are two facets of these frames. In interactive service work, control is complicated by the fact that a third party, the customer, is involved and that the borders between worker, work process and result are somewhat indistinct. Indirect forms of control can be used to affect workers' attitudes and thinking, as well as behaviour.

    Service work can be described as a form of acting. Different service workers will identify differently with their work role. In my study I observe both positive and negative experiences of work. A majority report that they sometimes are so tired of people that they want to be alone after work.

    I distinguish two dimensions of interactive service work: type of interaction and sales situation. Interaction can be more or less important, and the sales situation can be more or less concealed. Based on these dimensions I suggest a typology to illustrate some differences between different service occupations. Four types are suggested: (1) Work first, and customer later; (2) Personalised services; (3) Routine selling; and (4) Persuasive selling. In the second group we find the experts of interaction, but also the strongest signs of social strain.

  • 284. Abiala, Kristina
    et al.
    Hernwall, Patrik
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Tweens konstruerar identitet online – flickors och pojkars erfarenheter av sociala medier2013In: Pedagogisk forskning i Sverige, ISSN 1401-6788, E-ISSN 2001-3345, Vol. 18, no 1-2Article in journal (Refereed)
  • 285. Abiala, Kristina
    et al.
    Hernwall, Patrik
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Tweens negotiating identity online – Swedish girls' and boys' reflections on online experiences2013In: Journal of Youth Studies, ISSN 1367-6261, E-ISSN 1469-9680, Vol. 16, no 8, p. 951-969Article in journal (Refereed)
    Abstract [en]

    How do Swedish tweens (10–14 years old) understand and experience the writing of their online identities? How are such intertwined identity markers as gender and age expressed and negotiated? To find some answers to these questions, participants in this study were asked to write a story about the use of online web communities on pre-prepared paper roundels with buzzwords in the margins to inspire them. Content analysis of these texts using the constant comparative method showed that the main factors determining how online communities are understood and used are the cultural age and gender of the user. Both girls and boys chat online, but girls more often create blogs while boys more often play games. Gender was increasingly emphasised with age; but whereas boys aged 14 described themselves as sexually active and even users of pornography, girls of the same age described themselves as shocked and repelled by pornography and fearful of sexual threats. In this investigation an intersectionalist frame of reference is used to elucidate the intertwined power differentials and identity markers of the users' peer group situation.

  • 286. Abiven, Samuel
    et al.
    Hund, Andreas
    Martinsen, Vegard
    Cornelissen, Gerard
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM). Norwegian University of Life Sciences (NMBU), Norway; Norwegian Geotechnical Institute (NGI), Norway .
    Biochar amendment increases maize root surface areas and branching: a shovelomics study in Zambia2015In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 395, no 1-2, p. 45-55Article in journal (Refereed)
    Abstract [en]

    Positive crop yield effects from biochar are likely explained by chemical, physical and/or biological factors. However, studies describing plant allometric changes are scarcer, but may be crucial to understand the biochar effect. The main aim of the present study is to investigate the effect of biochar on root architecture under field conditions in a tropical setting. The presented work describes a shovelomics (i.e., description of root traits in the field) study on the effect of biochar on maize root architecture. Four field experiments we carried out at two different locations in Zambia, exhibiting non-fertile to relatively fertile soils. Roots of maize crop (Zea mays L.) were sampled from treatments with fertilizer (control) and with a combination of fertilizer and 4 t.ha(-1) maize biochar application incorporated in the soil. For the four sites, the average grain yield increase upon biochar addition was 45 +/- 14 % relative to the fertilized control (from 2.1-6.0 to 3.1-9.1 ton ha(-1)). The root biomass was approximately twice as large for biochar-amended plots. More extensive root systems (especially characterized by a larger root opening angle (+14 +/- 11 %) and wider root systems (+20 +/- 15 %)) were observed at all biochar-amended sites. Root systems exhibited significantly higher specific surface areas (+54 +/- 14 %), branching and fine roots: +70 +/- 56 %) in the presence of biochar. Biochar amendment resulted in more developed root systems and larger yields. The more extensive root systems may have contributed to the observed yield increases, e.g., by improving immobile nutrients uptake in soils that are unfertile or in areas with prolonged dry spells.

  • 287. Aboagye, Emmanuel
    et al.
    Björklund, Christina
    Gustafsson, Klas
    Hagberg, Jan
    Aronsson, Gunnar
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Work and organizational psychology.
    Marklund, Staffan
    Leineweber, Constanze
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Bergström, Gunnar
    Exhaustion and Impaired Work Performance in the Workplace: Associations With Presenteeism and Absenteeism2019In: Journal of Occupational and Environmental Medicine, ISSN 1076-2752, E-ISSN 1536-5948, Vol. 61, no 11, p. 438-444Article in journal (Refereed)
    Abstract [en]

    Objective: The aim of this study was to investigate the association between presenteeism and absenteeism during the previous year and the current levels of exhaustion and impaired work performance in a Swedish university setting.

    Methods: In a study of 3525 employees, an ordinal logistic regression and general linear model was used to examine the association between presenteeism and absenteeism during the previous year and the current exhaustion and impaired work performance, respectively.

    Results: Presenteeism, but not absenteeism, during the previous year independently increased the risk of having moderate or severe exhaustion. Presenteeism, absenteeism, and exhaustion remained positively associated with impaired work performance when health status and other confounders had been adjusted for.

    Conclusions: Presenteeism, but not absenteeism, was associated with exhaustion. Both presenteeism and absenteeism were the salient correlates of impaired work performance.

  • 288. Abolmasov, Pavel
    et al.
    Poutanen, Juri
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita). University of Turku, Finland.
    Gamma-ray opacity of the anisotropic stratified broad-line regions in blazars2017In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 464, no 1, p. 152-169Article in journal (Refereed)
    Abstract [en]

    The GeV-range spectra of blazars are shaped not only by non-thermal emission processes internal to the relativistic jet but also by external pair-production absorption on the thermal emission of the accretion disc and the broad-line region (BLR). For the first time, we compute here the pair-production opacities in the GeV range produced by a realistic BLR accounting for the radial stratification and radiation anisotropy. Using photoionization modelling with the CLOUDY code, we calculate a series of BLR models of different sizes, geometries, cloud densities, column densities and metallicities. The strongest emission features in the model BLR are Ly alpha and He II Ly alpha. Contribution of recombination continua is smaller, especially for hydrogen, because Ly continuum is efficiently trapped inside the large optical depth BLR clouds and converted to Lyman emission lines and higher order recombination continua. The largest effects on the gamma-ray opacity are produced by the BLR geometry and localization of the gamma-ray source. We show that when the gamma-ray source moves further from the central source, all the absorption details move to higher energies and the overall level of absorption drops because of decreasing incidence angles between the gamma-rays and BLR photons. The observed positions of the spectral breaks can be used to measure the geometry and the location of the gamma-ray emitting region relative to the BLR. Strong dependence on geometry means that the soft photons dominating the pair-production opacity may be actually produced by a different population of BLR clouds than the bulk of the observed broad line emission.

  • 289. Abor, J
    et al.
    Graham, Michael
    School of Economics, Finance, and Marketing, Royal Melbourne Institute of Technology University (RMIT) University.
    Yawson, A
    Corporate Governance and Restructuring Activities following Completed Bids2011In: Corporate governance: An International Review, ISSN 0964-8410, E-ISSN 1467-8683, Vol. 19, no 1, p. 61-76Article in journal (Refereed)
    Abstract [en]

    Research Question/Issue: We examine the extent to which effective corporate governance impacts three restructuring choices following completed acquisitions – significant adjustment to workforce; sale of subsidiaries; and further acquisitions. We also investigate the relative firm performance in the post-restructuring period for the three respective options examined.

    Research Findings/Insights: Based on a sample of 649 US firms between the period 1991 and 2009, we find support for the assertion that corporate governance impacts layoffs and further acquisitions. We, however, find no evidence to support a measurable governance effect on divestiture likelihood. In examining the post-acquisition performance following restructuring, we find no significant difference in performance between acquirers that made further acquisitions and those that did not. There is evidence, however, suggesting that acquirers who laid off workers and those that divested assets performed significantly poorer relative to a comparable group of acquirers.

    Theoretical/Academic Implications: This study adds to the empirical literature on the relation between governance and restructuring choices. We provide evidence on the impact of governance on restructuring choices that has not been documented in the academic literature. An implication of this study is that performance in post-restructuring period would not necessarily be enhanced even when governance exerts positive influences on restructuring choice.

    Practitioner/Policy Implications: Our empirical results demonstrate the relative importance of corporate governance in organizational strategic choices. This study offers insights to stakeholders interested in enhancing governance structures to influence restructuring decisions following completed bids.

  • 290. Abraham, Arpad
    et al.
    Koehne, Sebastian
    Stockholm University, Faculty of Social Sciences, Institute for International Economic Studies.
    Pavoni, Nicola
    On the first-order approach in principal agent models with hidden borrowing and lending2011In: Journal of Economic Theory, ISSN 0022-0531, E-ISSN 1095-7235, Vol. 146, no 4, p. 1331-1361Article in journal (Refereed)
    Abstract [en]

    We provide sufficient conditions for the validity of the first-order approach for two-period dynamic moral hazard problems where the agent can save and borrow secretly. The first-order approach is valid if the following conditions hold: (i) the agent has non-increasing absolute risk aversion utility (NIARA), (ii) the output technology has monotone likelihood ratios (MLR), and (iii) the distribution function of output is log-convex in effort (LCDF). Moreover, under these three conditions, the optimal contract is monotone in output. We also investigate a few possibilities of relaxing these requirements.

  • 291. Abraham, Arpad
    et al.
    Koehne, Sebastian
    Stockholm University, Faculty of Social Sciences, Institute for International Economic Studies. CESifo, Germany.
    Pavoni, Nicola
    Optimal income taxation when asset taxation is limited2016In: Journal of Public Economics, ISSN 0047-2727, E-ISSN 1879-2316, Vol. 136, p. 14-29Article in journal (Refereed)
    Abstract [en]

    Several frictions restrict the government's ability to tax assets. First, it is very costly to monitor trades on international asset markets. Second, agents can resort to nonobservable low-return assets such as cash, gold or foreign currencies if taxes on observable assets become too high. This paper shows that limitations in asset taxation have important consequences for the taxation of labor income. We study a simple dynamic moral hazard model of social insurance with observable and nonobservable saving decisions. We find that optimal labor income taxes become less progressive when the ability to tax savings is limited.

  • 292. Abraham, Mark
    et al.
    Apostolov, Rossen
    Barnoud, Jonathan
    Bauer, Paul
    Blau, Christian
    Bonvin, Alexandre M. J. J.
    Chavent, Matthieu
    Chodera, John
    Condic-Jurkic, Karmen
    Delemotte, Lucie
    Grubmueller, Helmut
    Howard, Rebecca J.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Jordan, E. Joseph
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Lindahl, Erik
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Ollila, O. H. Samuli
    Selent, Jana
    Smith, Daniel G. A.
    Stansfeld, Phillip J.
    Tiemann, Johanna K. S.
    Trellet, Mikael
    Woods, Christopher
    Zhmurov, Artem
    Sharing Data from Molecular Simulations2019In: Journal of Chemical Information and Modeling, ISSN 1549-9596, E-ISSN 1549-960X, Vol. 59, no 10, p. 4093-4099Article in journal (Refereed)
    Abstract [en]

    Given the need for modern researchers to produce open, reproducible scientific output, the lack of standards and best practices for sharing data and workflows used to produce and analyze molecular dynamics (MD) simulations has become an important issue in the field. There are now multiple well-established packages to perform molecular dynamics simulations, often highly tuned for exploiting specific classes of hardware, each with strong communities surrounding them, but with very limited interoperability/transferability options. Thus, the choice of the software package often dictates the workflow for both simulation production and analysis. The level of detail in documenting the workflows and analysis code varies greatly in published work, hindering reproducibility of the reported results and the ability for other researchers to build on these studies. An increasing number of researchers are motivated to make their data available, but many challenges remain in order to effectively share and reuse simulation data. To discuss these and other issues related to best practices in the field in general, we organized a workshop in November 2018 (https://bioexcel.eu/events/workshop-on-sharing-data-from-molecular-simulations/). Here, we present a brief overview of this workshop and topics discussed. We hope this effort will spark further conversation in the MD community to pave the way toward more open, interoperable, and reproducible outputs coming from research studies using MD simulations.

  • 293. Abrahamczyk, S.
    et al.
    Kessler, M.
    Hanley, D.
    Karger, D. N.
    Mueller, M. P. J.
    Knauer, A. C.
    Keller, F.
    Schwerdtfeger, M.
    Humphreys, Aelys M.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Imperial College London, UK.
    Pollinator adaptation and the evolution of floral nectar sugar composition2017In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 30, no 1, p. 112-127Article in journal (Refereed)
    Abstract [en]

    A long-standing debate concerns whether nectar sugar composition evolves as an adaptation to pollinator dietary requirements or whether it is 'phylogenetically constrained'. Here, we use a modelling approach to evaluate the hypothesis that nectar sucrose proportion (NSP) is an adaptation to pollinators. We analyse similar to 2100 species of asterids, spanning several plant families and pollinator groups (PGs), and show that the hypothesis of adaptation cannot be rejected: NSP evolves towards two optimal values, high NSP for specialist-pollinated and low NSP for generalist-pollinated plants. However, the inferred adaptive process is weak, suggesting that adaptation to PG only provides a partial explanation for how nectar evolves. Additional factors are therefore needed to fully explain nectar evolution, and we suggest that future studies might incorporate floral shape and size and the abiotic environment into the analytical framework. Further, we show that NSP and PG evolution are correlated - in a manner dictated by pollinator behaviour. This contrasts with the view that a plant necessarily has to adapt its nectar composition to ensure pollination but rather suggests that pollinators adapt their foraging behaviour or dietary requirements to the nectar sugar composition presented by the plants. Finally, we document unexpectedly sucrose-poor nectar in some specialized nectarivorous bird-pollinated plants from the Old World, which might represent an overlooked form of pollinator deception. Thus, our broad study provides several new insights into how nectar evolves and we conclude by discussing why maintaining the conceptual dichotomy between adaptation and constraint might be unhelpful for advancing this field.

  • 294.
    Abrahamson, Maria
    Stockholm University, Faculty of Social Sciences, Centre for Social Research on Alcohol and Drugs (SoRAD).
    Alcohol in courtship contexts. Focus group interviews with young Swedish women and men2004In: Contemporary Drug Problems, ISSN 0091-4509, E-ISSN 2163-1808, Vol. 31, p. 3-29Article in journal (Refereed)
  • 295.
    Abrahamson, Maria
    Stockholm University, Faculty of Social Sciences, Centre for Social Research on Alcohol and Drugs (SoRAD).
    Alkohol och mötet mellan unga kvinnor och män2003In: Nordisk Alkohol- og narkotikatidsskrift (NAT), ISSN 1455-0725, E-ISSN 1458-6126, Vol. 20, no 4, p. 227-239Article in journal (Refereed)
  • 296.
    Abrahamson, Maria
    Stockholm University, Faculty of Social Sciences, Centre for Social Research on Alcohol and Drugs (SoRAD).
    Alkohol och unga i 20-årsåldern - rus, lust, problem och prevention2004Report (Other academic)
  • 297.
    Abrahamson, Maria
    Stockholm University, Faculty of Social Sciences, Department of Social Work.
    Alkoholkontroll i brytningstid: ett kultursociologiskt perspektiv1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The dissertation is a product of four separate cultural studies, intended to throw light on the changes in Swedish alcohol policy taking place in recent years.

    Paper 1 discusses factors contributing to the rapid proliferation of restaurants in Sweden in the 1980’s and the subsequent tensions arising from a restrictive legislation, an increasingly liberal legal praxis and the new, public alcohol culture. Urban transformations and changes in public life, the transition from modem to late modernism, the emergence of a new middle class and the redefinition of women’s use of alcohol were among the crucial developments. Beginning in the late 1950’s and early 1960’s, important steps away from the traditionally strict control of restaurants stimulated competition and led to a loosening up of Swedish restaurant culture. By the 1980’s, the restrictive laws governing restaurants had begun to lose legitimacy as legal praxis was applied in an increasingly liberal spirit. The establishment of the Stockholm Water Festival, which allowed central parts of the city to be transformed into a gigantic beer hall, is one example of this. As in many other countries, age limits have now become almost the only actual restriction on the availability of alcohol. Today, rather than protection, the aim of alcohol policy - especially with regard to restaurants - is keeping damage to a minimum.

    Paper 2 is based on participant observation in three types of restaurants in Stockholm’s city centre. These are characterised as ‘the fashionable bar’, ‘the folksy bar’, and ‘the ethnic bar’. The study takes its starting point in Goffman’s (1956) concepts of ‘performance’, ‘setting’ and ‘personal front’, and how people consciously or unconsciously choose different milieus as a way of controlling the impression of themselves they wish to project. The fashionable bar clearly functioned as an arena for demonstrating professional and social success. The folksy bar could be used as the setting for a form of play in which company colleagues could temporarily set aside their differences in status. The closed room of the ethnic bar encouraged ‘time-out’ behaviour - seeming to serve as a second home, but also as a sex market for contacts between African men and Nordic women.

    Paper 3 presents an analysis of how five different occupational groups discuss their alcohol habits in serious compared to humorous speech. The occupational areas are media, politics, business, culture and civil service. In serious speech, the speakers tended to value cautious drinking, setting sharp limits as to how and when use of alcohol is appropriate. In humorous speech, the situation was largely the opposite - the interviewees often presenting themselves as being under external constraints with regard to alcohol. The situations that provoked humour are also where we find controversy in serious speech. Discrepancies between alcohol habits and the role model one represents as a parent gave rise to a number of jokes. The parts of serious discourse that concerned other people displayed a very different content, dealing with excessive drinking, not being able to handle alcohol and not being permitted to drink alcohol - a content reflected in humorous form when the interviewees talked about themselves.

    Paper 4, based on the same interview data as Paper 3, examines the issue of youth and alcohol. Common dividing lines between the groups could be observed, such as describing the problem as an individual, personal or family affair versus seeing it as a problem for the society, or placing responsibility for problem control on the individual as opposed to placing responsibility on the society. Those active in cultural pursuits viewed teenage use and abuse of alcohol as a social problem, but placed responsibility for its solution on a private, individual level. Journalists saw the problem as belonging within the family, which is also where they placed responsibility for the solution. The politicians clearly perceived teenage drinking as a problem for the society and placed responsibility for solutions on outer agents, such as legislation and extensive information campaigns. Civil servants described the problem both in terms of belonging within the family and as a problem for the society. Business executives varied between the level on which they described the problem and the level on which they sought solutions. In considering the problem from the point of view of the consumer, they stressed individual responsibility. But as the discussion progressed, they came to see teenage drinking both as a family problem and a problem for the society and to place responsibility on outer authorities.

    The four studies are linked together in an introductory chapter within the common framework of Swedish alcohol control policy.

  • 298.
    Abrahamson, Maria
    Stockholm University, Faculty of Social Sciences, Centre for Social Research on Alcohol and Drugs (SoRAD).
    Diskursiv analys av fokusgruppintervjuer: två exempel2005In: Forskningsmetoder i socialt arbete / [ed] S. Larsson, J. Lilja & K. Mannheimer, Lund: Studentlitteratur , 2005Chapter in book (Other academic)
  • 299.
    Abrahamson, Maria
    Stockholm University, Faculty of Social Sciences, Centre for Social Research on Alcohol and Drugs (SoRAD).
    Moral norms in older Swedish women’s drinking narratives. Enduring patterns and successively new features2012In: Nordic Studies on Alcohol and Drugs, ISSN 1455-0725, Vol. 29, no 4, p. 371-396Article in journal (Refereed)
    Abstract [en]

    AIMS - To examine how the changes in women's relationship to alcohol during the 1960s appear in narratives of situated drinking occasions. DATA - Newly collected autobiographies written by women born between 1918 and 1951 are analysed using theories by William Labov on narrative construction and Kenneth Burke on the rhetoric of motives. RESULTS - The historically restrictive attitude to women at all drinking is present in the oldest women's narratives, while the liberalisation of attitudes to alcohol that took place in the 1960s likewise marks the narratives told by the younger women, even though they when writing are of pension able age. With the writers' diminishing age, the norms framing the narratives have changed, from sobriety among the oldest women to controlled moderation among the younger. And yet, the narratives also demonstrate a stable pattern of questioning women's drinking, although the focus has shifted from tasting alcohol at all to the state of becoming intoxicated. CONCLUSIONS - A controlling norm remains in place, which the women have internalised and made their own. The mitigating circumstances and the neutralising explanations that are presented throughout indicate that the women are conscious of the narratives' deviation from the prevailing norm, and show that women take a risk in drinking alcohol. When a woman drinks she risks her femininity.

  • 300.
    Abrahamson, Maria
    Stockholm University, Faculty of Social Sciences, Centre for Social Research on Alcohol and Drugs (SoRAD).
    När jag drack för mycket: unga i 20-årsåldern berättar2003In: Nordisk Alkohol- og narkotikatidsskrift (NAT), ISSN 1455-0725, E-ISSN 1458-6126, Vol. 20, no 6, p. 395-408Article in journal (Refereed)
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