Change search
Refine search result
12345 151 - 200 of 207
CiteExportLink to result list
Permanent link
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)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest 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)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest 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.
  • 151. Paris-Mandoki, A.
    et al.
    Shearring, J.
    Mancarella, Francesco
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Fromhold, T. M.
    Trombettoni, A.
    Krüger, P.
    Superfluid flow above the critical velocity2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 9070Article in journal (Refereed)
    Abstract [en]

    Superfluidity and superconductivity have been widely studied since the last century in many different contexts ranging from nuclear matter to atomic quantum gases. The rigidity of these systems with respect to external perturbations results in frictionless motion for superfluids and resistance-free electric current flow in superconductors. This peculiar behaviour is lost when external perturbations overcome a critical threshold, i.e. above a critical magnetic field or a critical current for superconductors. In superfluids, such as liquid helium or ultracold gases, the corresponding quantities are a critical rotation rate and a critical velocity respectively. Enhancing the critical values is of great fundamental and practical value. Here we demonstrate that superfluidity can be completely restored for specific, arbitrarily large flow velocities above the critical velocity through quantum interference-induced resonances providing a nonlinear counterpart of the Ramsauer-Townsend effect occurring in ordinary quantum mechanics. We illustrate the robustness of this phenomenon through a thorough analysis in one dimension and prove its generality by showing the persistence of the effect in non-trivial 2d systems. This has far reaching consequences for the fundamental understanding of superfluidity and superconductivity and opens up new application possibilities in quantum metrology, e.g. in rotation sensing.

  • 152. Peralta-Maraver, Ignacio
    et al.
    Galloway, Jason
    Posselt, Malte
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Arnon, Shai
    Reiss, Julia
    Lewandowski, Joerg
    Robertson, Anne L.
    Environmental filtering and community delineation in the streambed ecotone2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 15871Article in journal (Refereed)
    Abstract [en]

    A current controversy in ecology is whether biological communities are discrete biological entities or simply study units created for convenience; a debate that becomes even more heated when delimiting communities along ecotones. Here, we report an interdisciplinary study designed to address the interplay between environmental drivers and community ecology in a typical ecotone ecosystem: the streambed. Environmental filtering at a micro-scale determined how diversity, productivity and composition of the whole streambed assemblage varied with depth and with the direction of vertical water exchange. Biomass and production decreased with increasing depth, and were lower under upwelling than downwelling conditions. However, the rate at which biomass and production decreased with increasing depth differed significantly for different taxonomic groups. Using quantitative biocenosis analysis, we also showed that benthic and hyporheic zone assemblages (assemblages in close juxtaposition) could be clearly distinguished as discrete communities with individual integrity. Vertical hydrodynamic conditions also influenced the demarcation between both communities; the benthic community reached greater depths in downwelling than in upwelling zones.

  • 153. Persoiu, Aurel
    et al.
    Onac, Bogdan P.
    Wynn, Jonathan G.
    Blaauw, Maarten
    Ionita, Monica
    Hansson, Margareta
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Holocene winter climate variability in Central and Eastern Europe2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 1196Article in journal (Refereed)
    Abstract [en]

    Among abundant reconstructions of Holocene climate in Europe, only a handful has addressed winter conditions, and most of these are restricted in length and/or resolution. Here we present a record of late autumn through early winter air temperature and moisture source changes in East-Central Europe for the Holocene, based on stable isotopic analysis of an ice core recovered from a cave in the Romanian Carpathian Mountains. During the past 10,000 years, reconstructed temperature changes followed insolation, with a minimum in the early Holocene, followed by gradual and continuous increase towards the mid-to-late-Holocene peak (between 4-2 kcal BP), and finally by a decrease after 0.8 kcal BP towards a minimum during the Little Ice Age (AD 1300-1850). Reconstructed early Holocene atmospheric circulation patterns were similar to those characteristics of the negative phase of the North Atlantic Oscillation (NAO), while in the late Holocene they resembled those prevailing in the positive NAO phase. The transition between the two regimes occurred abruptly at around 4.7 kcal BP. Remarkably, the widespread cooling at 8.2 kcal BP is not seen very well as a temperature change, but as a shift in moisture source, suggesting weaker westerlies and increased Mediterranean cyclones penetrating northward at this time.

  • 154. Petoukhov, Vladimir
    et al.
    Petri, Stefan
    Kornhuber, Kai
    Thonicke, Kirsten
    Coumou, Dim
    Schellnhuber, Hans Joachim
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Potsdam Institute for Climate Impact Research (PIK), Germany.
    Alberta wildfire 2016: Apt contribution from anomalous planetary wave dynamics2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 12375Article in journal (Refereed)
    Abstract [en]

    In May-June 2016 the Canadian Province of Alberta suffered one of the most devastating wildfires in its history. Here we show that in mid-April to early May 2016 the large-scale circulation in the mid-and high troposphere of the middle and sub-polar latitudes of the northern hemisphere featured a persistent high-amplitude planetary wave structure dominated by the non-dimensional zonal wave number 4. The strongest anticyclonic wing of this structure was located over western Canada. In combination with a very strong El Nino event in winter 2015/2016 this favored highly anomalous, tinder-dry and high-temperature conditions at the surface in that area, entailing an increased fire hazard there. This critically contributed to the ignition of the Alberta Wildfire in May 2016, appearing to be the costliest disaster in Canadian history thus far.

  • 155. Petrini, Michele
    et al.
    Colleoni, Florence
    Kirchner, Nina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Hughes, Anna L. C.
    Camerlenghi, Angelo
    Rebesco, Michele
    Lucchi, Renata G.
    Forte, Emanuele
    Colucci, Renato R.
    Noormets, Riko
    Interplay of grounding-line dynamics and sub-shelf melting during retreat of the Bjornoyrenna Ice Stream2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 7196Article in journal (Refereed)
    Abstract [en]

    The Barents Sea Ice Sheet was a marine-based ice sheet, i.e., it rested on the Barents Sea floor during the Last Glacial Maximum (21 ky BP). The Bjornoyrenna Ice Stream was the largest ice stream draining the Barents Sea Ice Sheet and is regarded as an analogue for contemporary ice streams in West Antarctica. Here, the retreat of the Bjornoyrenna Ice Stream is simulated by means of two numerical ice sheet models and results assessed against geological data. We investigate the sensitivity of the ice stream to changes in ocean temperature and the impact of grounding-line physics on ice stream retreat. Our results suggest that the role played by sub-shelf melting depends on how the grounding-line physics is represented in the models. When an analytic constraint on the ice flux across the grounding line is applied, the retreat of Bjornoyrenna Ice Stream is primarily driven by internal ice dynamics rather than by oceanic forcing. This suggests that implementations of grounding-line physics need to be carefully assessed when evaluating and predicting the response of contemporary marine-based ice sheets and individual ice streams to ongoing and future ocean warming.

  • 156.
    Pečnerová, Patrícia
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    Diez-del-Molino, David
    Vartanyan, Sergey
    Dalén, Love
    Changes in variation at the MHC class II DQA locus during the final demise of the woolly mammoth2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 25274Article in journal (Refereed)
    Abstract [en]

    According to the nearly-neutral theory of evolution, the relative strengths of selection and drift shift in favour of drift at small population sizes. Numerous studies have analysed the effect of bottlenecks and small population sizes on genetic diversity in the MHC, which plays a central role in pathogen recognition and immune defense and is thus considered a model example for the study of adaptive evolution. However, to understand changes in genetic diversity at loci under selection, it is necessary to compare the genetic diversity of a population before and after the bottleneck. In this study, we analyse three fragments of the MHC DQA gene in woolly mammoth samples radiocarbon dated to before and after a well-documented bottleneck that took place about ten thousand years ago. Our results indicate a decrease in observed heterozygosity and number of alleles, suggesting that genetic drift had an impact on the variation on MHC. Based on coalescent simulations, we found no evidence of balancing selection maintaining MHC diversity during the Holocene. However, strong trans-species polymorphism among mammoths and elephants points to historical effects of balancing selection on the woolly mammoth lineage.

  • 157.
    Piech, Richard M.
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Perception and psychophysics. Anglia Ruskin University, UK.
    Strelchuk, Daniela
    Knights, Jake
    Hjälmheden, Jonathan V.
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Olofsson, Jonas K.
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Perception and psychophysics.
    Aspell, Jane E.
    People with higher interoceptive sensitivity are more altruistic, but improving interoception does not increase altruism2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 15652Article in journal (Refereed)
    Abstract [en]

    People consistently show preferences and behaviors that benefit others at a cost to themselves, a phenomenon termed altruism. We investigated if perception of one's body signals - interoception - may be underlying such behaviors. We tested if participants' sensitivity to their own heartbeat predicted their decision on a choice between self-interest and altruism, and if improving this sensitivity through training would make participants more altruistic. Across these two experiments, interoceptive sensitivity predicted altruism measured through monetary generosity. Improving interoceptive sensitivity did, however, not lead to more altruistic behaviour. We conclude that there is a unique link between interoception and altruistic behaviour, likely established over an individual's history of altruistic acts, and the body responses they elicit. The findings suggest that humans might literally 'listen to their heart' to guide their altruistic behavior.

  • 158. Poletti, Sophia C.
    et al.
    Cavazzana, Annachiara
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Perception and psychophysics. Technische Universität Dresden, Germany.
    Guducu, Cagdas
    Larsson, Maria
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Perception and psychophysics.
    Hummel, Thomas
    Indistinguishable odour enantiomers: Differences between peripheral and central-nervous electrophysiological responses2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 8978Article in journal (Refereed)
    Abstract [en]

    The ability of humans to discriminate enantiomeric odour pairs is substance-specific. Current literature suggests that psychophysical discrimination of odour enantiomers mainly depends on the peripheral processing at the level of the olfactory sensory neurons (OSN). To study the influence of central processing in discrimination, we investigated differences in the electrophysiological responses to psychophysically indistinguishable (+)- and (-)- rose oxide enantiomers at peripheral and central-nervous levels in humans. We recorded the electro-olfactogram (EOG) from the olfactory epithelium and the EEG-derived olfactory event-related potentials (OERP). Results from a psychophysical three alternative forced choice test indicated indistinguishability of the two odour enantiomers. In a total of 19 young participants EOG could be recorded in 74 and OERP in 95% of subjects. Significantly different EOG amplitudes and latencies were recorded in response to the 2 stimuli. However, no such differences in amplitude or latency emerged for the OERP. In conclusion, although the pair of enantiomer could be discriminated at a peripheral level this did not lead to a central-nervous/cognitive differentiation of the two stimuli.

  • 159. Polido Legaria, Elizabeth
    et al.
    Rocha, Joao
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Kessler, Vadim G.
    Seisenbaeva, Gulaim A.
    Unusual seeding mechanism for enhanced performance in solid-phase magnetic extraction of Rare Earth Elements2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 43740Article in journal (Refereed)
    Abstract [en]

    Due to the increasing demand of Rare Earth Elements (REE or RE), new and more efficient techniques for their extraction are necessary, suitable for both mining and recycling processes. Current techniques such as solvent extraction or solid adsorbents entail drawbacks such as using big volumes of harmful solvents or limited capacity. Hybrid nanoadsorbents based on SiO2 and highly stable gamma-Fe2O3-SiO2 nanoparticles, proved recently to be very attractive for adsorption of REE, yet not being the absolute key to solve the problem. In the present work, we introduce a highly appealing new approach in which the nanoparticles, rather than behaving as adsorbent materials, perform as inducers of crystallization for the REE in the form of hydroxides, allowing their facile and practically total removal from solution. This induced crystallization is achieved by tuning the pH, offering an uptake efficiency more than 20 times higher than previously reported (up to 900 mg RE3+/g vs. 40 mg RE3+/g). The obtained phases were characterized by SEM-EDS, TEM, STEM and EFTEM and C-13 and Si-29 solid state NMR. Magnetic studies showed that the materials possessed enough magnetic properties to be easily removed by a magnet, opening ways for an efficient and industrially applicable separation technique.

  • 160. Procaccini, Gabriele
    et al.
    Ruocco, Miriam
    Marin-Guirao, Lazaro
    Dattolo, Emanuela
    Brunet, Christophe
    D'Esposito, Daniela
    Lauritano, Chiara
    Mazzuca, Silvia
    Serra, Ilia Anna
    Bernardo, Letizia
    Piro, Amalia
    Beer, Sven
    Björk, Mats
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Gullström, Martin
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Buapet, Pimchanok
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Prince of Songkla University, Thailand.
    Rasmusson, Lina M.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Felisberto, Paulo
    Gobert, Sylvie
    Runcie, John W.
    Silva, Joao
    Olive, Irene
    Costa, Monya M.
    Barrote, Isabel
    Santos, Rui
    Depth-specific fluctuations of gene expression and protein abundance modulate the photophysiology in the seagrass Posidonia oceanica2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 42890Article in journal (Refereed)
    Abstract [en]

    Here we present the results of a multiple organizational level analysis conceived to identify acclimative/adaptive strategies exhibited by the seagrass Posidonia oceanica to the daily fluctuations in the light environment, at contrasting depths. We assessed changes in photophysiological parameters, leaf respiration, pigments, and protein and mRNA expression levels. The results show that the diel oscillations of P. oceanica photophysiological and respiratory responses were related to transcripts and proteins expression of the genes involved in those processes and that there was a response asynchrony between shallow and deep plants probably caused by the strong differences in the light environment. The photochemical pathway of energy use was more effective in shallow plants due to higher light availability, but these plants needed more investment in photoprotection and photorepair, requiring higher translation and protein synthesis than deep plants. The genetic differentiation between deep and shallow stands suggests the existence of locally adapted genotypes to contrasting light environments. The depth-specific diel rhythms of photosynthetic and respiratory processes, from molecular to physiological levels, must be considered in the management and conservation of these key coastal ecosystems.

  • 161.
    Riboni, Nicoló
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. University of Parma, Italy.
    Quaranta, Alessandro
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Motwani, Hitesh
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Österlund, Nickles
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Gräslund, Astrid
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Bianchi, Federica
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Solvent-Assisted Paper Spray Ionization Mass Spectrometry (SAPSI-MS) for the Analysis of Biomolecules and Biofluids2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 10296Article in journal (Refereed)
    Abstract [en]

    Paper Spray Ionization (PSI) is commonly applied for the analysis of small molecules, including drugs, metabolites, and pesticides in biological fluids, due to its high versatility, simplicity, and low costs. In this study, a new setup called Solvent Assisted Paper Spray Ionization (SAPSI), able to increase data acquisition time, signal stability, and repeatability, is proposed to overcome common PSI drawbacks. The setup relies on an integrated solution to provide ionization potential and constant solvent flow to the paper tip. Specifically, the ion source was connected to the instrument fluidics along with the voltage supply systems, ensuring a close control over the ionization conditions. SAPSI was successfully applied for the analysis of different classes of biomolecules: amyloidogenic peptides, proteins, and N-glycans. The prolonged analysis time allowed real-time monitoring of processes taking places on the paper tip, such as amyloid peptides aggregation and disaggregation phenomena. The enhanced signal stability allowed to discriminate protein species characterized by different post translational modifications and adducts with electrophilic compounds, both in aqueous solutions and in biofluids, such as serum and cerebrospinal fluid, without any sample pretreatment. In the next future, application to clinical relevant modifications, could lead to the development of quick and cost-effective diagnostic tools.

  • 162. Roy, Bitan
    et al.
    Juricic, Vladimir
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Sarma, Sankar Das
    Universal optical conductivity of a disordered Weyl semimetal2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 32446Article in journal (Refereed)
    Abstract [en]

    Topological Weyl semimetals, besides manifesting chiral anomaly, can also accommodate a disorder-driven unconventional quantum phase transition into a metallic phase. A fundamentally and practically important question in this regard concerns an experimentally measurable quantity that can clearly distinguish these two phases. We show that the optical conductivity while serving this purpose can also play the role of a bonafide order parameter across such disorder-driven semimetal-metal quantum phase transition by virtue of displaying distinct scaling behavior in the semimetallic and metallic phases, as well as inside the quantum critical fan supporting a non-Fermi liquid. We demonstrate that the correction to the dielectric constant and optical conductivity in a dirty Weyl semimetal due to weak disorder is independent of the actual nature of point-like impurity scatterers. Therefore, optical conductivity can be used as an experimentally measurable quantity to study the critical properties and to pin the universality class of the disorder-driven quantum phase transition in Weyl semimetals.

  • 163. Rybski, Diego
    et al.
    Buldyrev, Sergey V.
    Havlin, Shlomo
    Liljeros, Fredrik
    Stockholm University, Faculty of Social Sciences, Department of Sociology. Institute for Futures Studies, Sweden.
    Makse, Hernán A.
    Communication activity in a social network: relation between long-term correlations and inter-event clustering2012In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 2, article id 560Article in journal (Refereed)
    Abstract [en]

    Human communication in social networks is dominated by emergent statistical laws such as non-trivial correlations and temporal clustering. Recently, we found long-term correlations in the user's activity in social communities. Here, we extend this work to study the collective behavior of the whole community with the goal of understanding the origin of clustering and long-term persistence. At the individual level, we find that the correlations in activity are a byproduct of the clustering expressed in the power-law distribution of inter-event times of single users, i.e. short periods of many events are separated by long periods of no events. On the contrary, the activity of the whole community presents long-term correlations that are a true emergent property of the system, i.e. they are not related to the distribution of inter-event times. This result suggests the existence of collective behavior, possibly arising from nontrivial communication patterns through the embedding social network.

  • 164. Salama, Suzy M.
    et al.
    Gwaram, Nura Suleiman
    AlRashdi, Ahmed S.
    Khalifa, Shaden A. M.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Karolinska University Hospital, Sweden; Kumamoto University, Japan.
    Abdulla, Mahmood A.
    Ali, Hapipah M.
    El-Seedi, Hesham R.
    A Zinc Morpholine Complex Prevents HCl/Ethanol-Induced Gastric Ulcers in a Rat Model2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 29646Article in journal (Refereed)
    Abstract [en]

    Zinc is a naturally occurring element with roles in wound healing and rescuing tissue integrity, particularly in the gastrointestinal system, where it can be detected in the mucosal and submucosal layers. Zinc chelates are known to have beneficial effects on the gastrointestinal mucosa and in cases of gastric ulcer. We synthesized complexes of zinc featuring a heterocyclic amine binding amino acids then investigated their ability to enhance the gastric self-repair. Zinc-morpholine complex, Zn(L)SCN, namely showed strong free-radical scavenging, promotion of the DNA and RNA polymerases reconstruction and suppression of cell damage. The complex's mode of action is proposed to involve hydrogen bond formation via its bis(thiocyanato-k) zinc moiety. Zn(L) SCN complex had potent effects on gastric enzymatic activity both in vitro and in vivo. The complex disrupted the ulcerative process as demonstrated by changes in the intermediate metabolites of the oxidative pathway - specifically, reduction in the MDA levels and elevation of reduced glutathione together with an attenuation of oxidative DNA damage. Additionally, Zn(L) SCN restored the gastric mucosa, inhibited the production of pro-inflammatory cytokines (IL-6, TNF and the caspases), and preserved the gastric mucous balance. Zn(L) SCN thus exhibited anti-oxidative, anti-inflammatory and anti-apoptotic activities, all of which have cytoprotective effects on the gastric lining.

  • 165.
    Samrani, George
    et al.
    Stockholm University, Faculty of Social Sciences, Aging Research Center (ARC), (together with KI).
    Marklund, Petter
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Cognitive psychology.
    Engström, Lisa
    Broman, Daniel
    Persson, Jonas
    Stockholm University, Faculty of Social Sciences, Aging Research Center (ARC), (together with KI).
    Behavioral facilitation and increased brain responses from a high interference working memory context2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 15308Article in journal (Refereed)
    Abstract [en]

    Many real-life situations require flexible behavior in changing environments. Evidence suggests that anticipation of conflict or task difficulty results in behavioral and neural allocation of task-relevant resources. Here we used a high-and low-interference version of an item-recognition task to examine the neurobehavioral underpinnings of context-sensitive adjustment in working memory (WM). We hypothesized that task environments that included high-interference trials would require participants to allocate neurocognitive resources to adjust to the more demanding task context. The results of two independent behavioral experiments showed enhanced WM performance in the high-interference context, which indicated that a high-interference context improves performance on non-interference trials. A third behavioral experiment showed that when WM load was increased, this effect was no longer significant. Neuroimaging results further showed greater engagement of inferior frontal gyrus, striatum, parietal cortex, hippocampus, and midbrain in participants performing the task in the high-than in the low-interference context. This effect could arise from an active or dormant mode of anticipation that seems to engage fronto-striatal and midbrain regions to flexibly adjust resources to task demands. Our results extend the model of conflict adaptation beyond trial-to-trial adjustments by showing that a high interference context affects both behavioral and biological aspects of cognition.

  • 166.
    Saroj, Sunil D.
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Holmer, Linda
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Berengueras, Júlia M.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Jonsson, Ann-Beth
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Inhibitory role of acyl homoserine lactones in hemolytic activity and viability of Streptococcus pyogenes M6 S1652017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 44902Article in journal (Refereed)
    Abstract [en]

    Streptococcus pyogenes an adapted human pathogen asymptomatically colonizes the nasopharynx, among other polymicrobial communities. However, information on the events leading to the colonization and expression of virulence markers subject to interspecies and host-bacteria interactions are limited. The interference of acyl homoserine lactones (AHLs) with the hemolytic activity and viability of S. pyogenes M6 S165 was examined. AHLs, with fatty acid side chains >= 12 carbon atoms, inhibited hemolytic activity by downregulating the expression of the sag operon involved in the production of streptolysin S. Inhibitory AHLs upregulated the expression of transcriptional regulator LuxR. Electrophoretic mobility shift assays revealed the interaction of LuxR with the region upstream of sagA. AHL-mediated bactericidal activity observed at higher concentrations (mM range) was an energydependent process, constrained by the requirement of glucose and iron. Ferrichrome transporter FtsABCD facilitated transport of AHLs across the streptococcal membrane. The study demonstrates a previously unreported role for AHLs in S. pyogenes virulence.

  • 167. Schleussner, Carl-Friedrich
    et al.
    Donges, Jonathan F.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Potsdam Institute for Climate Impact Research, Germany.
    Engemann, Denis A.
    Levermann, Anders
    Clustered marginalization of minorities during social transitions induced by co-evolution of behaviour and network structure2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 30790Article in journal (Refereed)
    Abstract [en]

    Large-scale transitions in societies are associated with both individual behavioural change and restructuring of the social network. These two factors have often been considered independently, yet recent advances in social network research challenge this view. Here we show that common features of societal marginalization and clustering emerge naturally during transitions in a co-evolutionary adaptive network model. This is achieved by explicitly considering the interplay between individual interaction and a dynamic network structure in behavioural selection. We exemplify this mechanism by simulating how smoking behaviour and the network structure get reconfigured by changing social norms. Our results are consistent with empirical findings: The prevalence of smoking was reduced, remaining smokers were preferentially connected among each other and formed increasingly marginalized clusters. We propose that self-amplifying feedbacks between individual behaviour and dynamic restructuring of the network are main drivers of the transition. This generative mechanism for co-evolution of individual behaviour and social network structure may apply to a wide range of examples beyond smoking.

  • 168. Scholl, Michael
    et al.
    Carter, Stephen F.
    Westman, Eric
    Rodriguez-Vieitez, Elena
    Almkvist, Ove
    Stockholm University, Faculty of Social Sciences, Department of Psychology. Karolinska Institutet, Sweden; Karolinska University Hospital, Sweden.
    Thordardottir, Steinunn
    Wall, Anders
    Graff, Caroline
    Långström, Bengt
    Nordberg, Agneta
    Early astrocytosis in autosomal dominant Alzheimer's disease measured in vivo by multi-tracer positron emission tomography2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 16404Article in journal (Refereed)
    Abstract [en]

    Studying autosomal dominant Alzheimer's disease (ADAD), caused by gene mutations yielding nearly complete penetrance and a distinct age of symptom onset, allows investigation of presymptomatic pathological processes that can identify a therapeutic window for disease-modifying therapies. Astrocyte activation may occur in presymptomatic Alzheimer's disease (AD) because reactive astrocytes surround beta-amyloid (A beta) plaques in autopsy brain tissue. Positron emission tomography was performed to investigate fibrillar A beta, astrocytosis and cerebral glucose metabolism with the radiotracers C-11-Pittsburgh compound-B (PIB), C-11-deuterium-L-deprenyl (DED) and F-18-fluorodeoxyglucose (FDG) respectively in presymptomatic and symptomatic ADAD participants (n = 21), patients with mild cognitive impairment (n = 11) and sporadic AD (n = 7). Multivariate analysis using the combined data from all radiotracers clearly separated the different groups along the first and second principal components according to increased PIB retention/decreased FDG uptake (component 1) and increased DED binding (component 2). Presymptomatic ADAD mutation carriers showed significantly higher PIB retention than non-carriers in all brain regions except the hippocampus. DED binding was highest in presymptomatic ADAD mutation carriers. This suggests that non-fibrillar A beta or early stage plaque depostion might interact with inflammatory responses indicating astrocytosis as an early contributory driving force in AD pathology. The novelty of this finding will be investigated in longitudinal follow-up studies.

  • 169.
    Schäfer, Jacob
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Dawitz, Hannah
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Ott, Martin
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Ädelroth, Pia
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Brzezinski, Peter
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Regulation of cytochrome c oxidase activity by modulation of the catalytic site2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 11397Article in journal (Refereed)
    Abstract [en]

    The respiratory supercomplex factor 1 (Rcf 1) in Saccharomyces cerevisiae binds to intact cytochrome c oxidase (CytcO) and has also been suggested to be an assembly factor of the enzyme. Here, we isolated CytcO from rcf1Δ mitochondria using affinity chromatography and investigated reduction, inter-heme electron transfer and ligand binding to heme a3. The data show that removal of Rcf1 yields two CytcO sub-populations. One of these sub-populations exhibits the same functional behavior as CytcO isolated from the wild-type strain, which indicates that intact CytcO is assembled also without Rcf1. In the other sub-population, which was shown previously to display decreased activity and accelerated ligand-binding kinetics, the midpoint potential of the catalytic site was lowered. The lower midpoint potential allowed us to selectively reduce one of the two sub-populations of the rcf1Δ CytcO, which made it possible to investigate the functional behavior of the two CytcO forms separately. We speculate that these functional alterations reflect a mechanism that regulates O2 binding and trapping in CytcO, thereby altering energy conservation by the enzyme.

  • 170.
    Sjöholm, Johannes
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Bergstrand, Jan
    Nilsson, Tobias
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Šachl, Radek
    von Ballmoos, Christoph
    Widengren, Jerker
    Brzezinski, Peter
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    The lateral distance between a proton pump and ATP synthase determines the ATP-synthesis rate2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 2926Article in journal (Refereed)
    Abstract [en]

    We have investigated the effect of lipid composition on interactions between cytochrome bo(3) and ATP-synthase, and the ATP-synthesis activity driven by proton pumping. The two proteins were labeled by fluorescent probes and co-reconstituted in large (d congruent to 100 nm) or giant (d congruent to 10 mu m) unilamellar lipid vesicles. Interactions were investigated using fluorescence correlation/cross-correlation spectroscopy and the activity was determined by measuring ATP production, driven by electron-proton transfer, as a function of time. We found that conditions that promoted direct interactions between the two proteins in the membrane (higher fraction DOPC lipids or labeling by hydrophobic molecules) correlated with an increased activity. These data indicate that the ATP-synthesis rate increases with decreasing distance between cytochrome bo3 and the ATP-synthase, and involves proton transfer along the membrane surface. The maximum distance for lateral proton transfer along the surface was found to be similar to 80 nm.

  • 171. Skedung, Lisa
    et al.
    Arvidsson, Martin
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Chung, Jun Young
    Stafford, Christopher M.
    Berglund, Birgitta
    Stockholm University, Faculty of Social Sciences, Department of Psychology. Karolinska Institutet, Sweden.
    Rutland, Mark W.
    Feeling Small: Exploring the Tactile Perception Limits2013In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 3, p. 2617-Article in journal (Refereed)
    Abstract [en]

    The human finger is exquisitely sensitive in perceiving different materials, but the question remains as to what length scales are capable of being distinguished in active touch. We combine material science with psychophysics to manufacture and haptically explore a series of topographically patterned surfaces of controlled wavelength, but identical chemistry. Strain-induced surface wrinkling and subsequent templating produced 16 surfaces with wrinkle wavelengths ranging from 300 nm to 90 mu m and amplitudes between 7 nm and 4.5 mu m. Perceived similarities of these surfaces (and two blanks) were pairwise scaled by participants, and interdistances among all stimuli were determined by individual differences scaling (INDSCAL). The tactile space thus generated and its two perceptual dimensions were directly linked to surface physical properties - the finger friction coefficient and the wrinkle wavelength. Finally, the lowest amplitude of the wrinkles so distinguished was approximately 10 nm, demonstrating that human tactile discrimination extends to the nanoscale.

  • 172.
    Smirnova, Irina A.
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Ädelroth, Pia
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Brzezinski, Peter
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Extraction and liposome reconstitution of membrane proteins with their native lipids without the use of detergents2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 14950Article in journal (Refereed)
    Abstract [en]

    Functional studies of membrane-bound channels, transporters or signal transducers require that the protein of interest resides in a membrane that separates two compartments. One approach that is commonly used to prepare these systems is to reconstitute the protein in liposomes. An intermediate step of this method is purification of the protein, which typically involves solubilization of the native membrane using detergent. The use of detergents often results in removal of lipids surrounding the protein, which may alter its structure and function. Here, we have employed a method for isolation of membrane proteins with a disc of their native lipids to develop an approach that allows transfer of the purified membrane protein to liposomes without the use of any detergents.

  • 173. Sork, Helena
    et al.
    Corso, Giulia
    Krjutskov, Kaarel
    Johansson, Henrik J.
    Nordin, Joel Z.
    Wiklander, Oscar P. B.
    Lee, Yi Xin Fiona
    Orzechowski Westholm, Jakub
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Lehtiö, Janne
    Wood, Matthew J. A.
    Mäger, Imre
    El Andaloussi, Samir
    Heterogeneity and interplay of the extracellular vesicle small RNA transcriptome and proteome2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 10813Article in journal (Refereed)
    Abstract [en]

    Extracellular vesicles (EVs) mediate cell-to-cell communication by delivering or displaying macromolecules to their recipient cells. While certain broad-spectrum EV effects reflect their protein cargo composition, others have been attributed to individual EV-loaded molecules such as specific miRNAs. In this work, we have investigated the contents of vesicular cargo using small RNA sequencing of cells and EVs from HEK293T, RD4, C2C12, Neuro2a and C17.2. The majority of RNA content in EVs (49-96%) corresponded to rRNA-, coding-and tRNA fragments, corroborating with our proteomic analysis of HEK293T and C2C12 EVs which showed an enrichment of ribosome and translation-related proteins. On the other hand, the overall proportion of vesicular small RNA was relatively low and variable (2-39%) and mostly comprised of miRNAs and sequences mapping to piRNA loci. Importantly, this is one of the few studies, which systematically links vesicular RNA and protein cargo of vesicles. Our data is particularly useful for future work in unravelling the biological mechanisms underlying vesicular RNA and protein sorting and serves as an important guide in developing EVs as carriers for RNA therapeutics.

  • 174. Stelbrink, Pablo
    et al.
    Pinkert, Stefan
    Brunzel, Stefan
    Kerr, Jeremy
    Wheat, Christopher W.
    Stockholm University, Faculty of Science, Department of Zoology.
    Brandl, Roland
    Zeuss, Dirk
    Stockholm University, Faculty of Science, Department of Zoology. Philipps-Universität Marburg, Germany.
    Colour lightness of butterfly assemblages across North America and Europe2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 1760Article in journal (Refereed)
    Abstract [en]

    Melanin-based dark colouration is beneficial for insects as it increases the absorption of solar energy and protects against pathogens. Thus, it is expected that insect colouration is darker in colder regions and in regions with high humidity, where it is assumed that pathogen pressure is highest. These relationships between colour lightness, insect distribution, and climate between taxa and subtaxa across continents have never been tested and compared. Here we analysed the colour lightness of nearly all butterfly species of North America and Europe using the average colour lightness of species occurring within 50 km x 50 km grid cells across both continents as the dependent variable and average insolation, temperature and humidity within grid cells as explanatory variables. We compared the direction, strength and shape of these relationships between butterfly families and continents. On both continents, butterfly assemblages in colder and more humid regions were generally darker coloured than assemblages in warmer and less humid regions. Although these relationships differed in detail between families, overall trends within families on both continents were similar. Our results add further support for the importance of insect colour lightness as a mechanistic adaptation to climate that influences biogeographical patterns of species distributions.

  • 175.
    Stranne, Christian
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences. University of New Hampshire, USA.
    Mayer, Larry
    Weber, Thomas C.
    Ruddick, Barry R.
    Jakobsson, Martin
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Jerram, Kevin
    Weidner, Elizabeth
    Nilsson, Johan
    Stockholm University, Faculty of Science, Department of Meteorology .
    Gårdfeldt, Katarina
    Acoustic Mapping of Thermohaline Staircases in the Arctic Ocean2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 15192Article in journal (Refereed)
    Abstract [en]

    Although there is enough heat contained in inflowing warm Atlantic Ocean water to melt all Arctic sea ice within a few years, a cold halocline limits upward heat transport from the Atlantic water. The amount of heat that penetrates the halocline to reach the sea ice is not well known, but vertical heat transport through the halocline layer can significantly increase in the presence of double diffusive convection. Such convection can occur when salinity and temperature gradients share the same sign, often resulting in the formation of thermohaline staircases. Staircase structures in the Arctic Ocean have been previously identified and the associated double diffusive convection has been suggested to influence the Arctic Ocean in general and the fate of the Arctic sea ice cover in particular. A central challenge to understanding the role of double diffusive convection in vertical heat transport is one of observation. Here, we use broadband echo sounders to characterize Arctic thermohaline staircases at their full vertical and horizontal resolution over large spatial areas (100 s of kms). In doing so, we offer new insight into the mechanism of thermohaline staircase evolution and scale, and hence fluxes, with implications for understanding ocean mixing processes and ocean-sea ice interactions.

  • 176. Sumida, K.
    et al.
    Ishida, Y.
    Zhu, S.
    Ye, M.
    Pertsova, Anna
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Center for Quantum Materials (CQM), Sweden.
    Triola, Christopher
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Center for Quantum Materials (CQM), Sweden.
    Kokh, K. A.
    Tereshchenko, O. E.
    Balatsky, Alexander V.
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Center for Quantum Materials (CQM), Sweden; Los Alamos National Laboratory, USA; ETH Institute for Theoretical Studies, Switzerland; University of Connecticut, USA.
    Shin, S.
    Kimura, A.
    Prolonged duration of nonequilibrated Dirac fermions in neutral topological insulators2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 14080Article in journal (Refereed)
    Abstract [en]

    Topological insulators (TIs) possess spin-polarized Dirac fermions on their surface but their unique properties are often masked by residual carriers in the bulk. Recently, (Sb1-xBix)(2)Te-3 was introduced as a non-metallic TI whose carrier type can be tuned from n to p across the charge neutrality point. By using time-and angle-resolved photoemission spectroscopy, we investigate the ultrafast carrier dynamics in the series of (Sb1-xBix)(2)Te-3. The Dirac electronic recovery of similar to 10 ps at most in the bulk-metallic regime elongated to >400 ps when the charge neutrality point was approached. The prolonged nonequilibration is attributed to the closeness of the Fermi level to the Dirac point and to the high insulation of the bulk. We also discuss the feasibility of observing excitonic instability of (Sb1-xBix)(2)Te-3.

  • 177.
    Sundelin, Tina
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden; New York University, USA.
    Bayard, Frida
    Schwarz, Johanna
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Cybulski, Lukasz
    Petrovic, Predrag
    Axelsson, John
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Framing effect, probability distortion, and gambling tendency without feedback are resistant to two nights of experimental sleep restriction2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 8554Article in journal (Refereed)
    Abstract [en]

    Several studies suggest that sleep deprivation affects risky decision making. However, most of these are confounded by feedback given after each decision, indicating that decisions may be based on suboptimal feedback-learning rather than risk evaluation. Furthermore, few studies have investigated the effect of sleep loss on aspects of prospect theory, specifically the framing effect and probability distortion. In this within-subjects design, 25 people had (i) two nights of an 8 h sleep opportunity, and (ii) two nights of a 4 h sleep opportunity, in a counter-balanced order. Following the two nights, they performed a gambling task with no immediate feedback; for each round, they could either gamble for a full amount, or take a settlement framed as a gain or a loss for part of the amount. Sleep restriction did not significantly affect the tendency to gamble, the framing effect, or probability distortion, as compared to normal sleep. These results indicate that two nights of sleep restriction affects neither general gambling tendency, nor two of the main predictions of prospect theory. This resilience may be due to a less extreme sleep loss than in previous studies, but also indicates that learning components and risk biases should be separated when assessing the effect of sleep loss on risky behaviour.

  • 178.
    Sundqvist, Hanna S.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Holmgren, Karin
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Fohlmeister, J.
    Zhang, Qiong
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Bar Matthews, M.
    Spötl, C.
    Körnich, H.
    Evidence of a large cooling between 1690 and 1740 AD in southern Africa2013In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 3, article id 1767Article in journal (Refereed)
    Abstract [en]

    A 350-year-long, well-dated delta O-18 stalagmite record from the summer rainfall region in South Africa is positively correlated with regional air surface temperatures at interannual time scales. The coldest period documented in this record occurred between 1690 and 1740, slightly lagging the Maunder Minimum (1645-1710). A temperature reconstruction, based on the correlation between regional surface temperatures and the stalagmite delta O-18 variations, indicates that parts of this period could have been as much as 1.4 degrees C colder than today. Significant cycles of 22, 11 and 4.8 years demonstrate that the solar magnetic and the El Nino-Southern Oscillation cycle could be important drivers of multidecadal to interannual climate variability in this region. The observation that the most important driver of stalagmite delta O-18 on interannual time scales from this subtropical region is regional surface temperature cautions against deterministic interpretations of delta O-18 variations in low-latitude stalagmites as mainly driven by the amount of precipitation.

  • 179. Säterberg, Torbjörn
    et al.
    Jonsson, Tomas
    Yearsley, Jon
    Berg, Sofia
    Ebenman, Bo
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Linköping University, Sweden.
    A potential role for rare species in ecosystem dynamics2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 11107Article in journal (Refereed)
    Abstract [en]

    The ecological importance of common species for many ecosystem processes and functions is unquestionably due to their high a bundance. Yet, the importance of rare species is much less understood. Here we take a theoretical approach, exposing dynamical models of ecological networks to small perturbations, to explore the dynamical importance of rare and common species. We find that both species types contribute to the recovery of communities following generic perturbations (i.e. perturbations affecting all species). Yet, when perturbations are selective (i.e. affects only one species), perturbations to rare species have the most pronounced effect on community stability. We show that this is due to the strong indirect effects induced by perturbations to rare species. Because indirect effects typically set in at longer timescales, our results indicate that the importance of rare species may be easily overlooked and thus underrated. Hence, our study provides a potential ecological motive for the management and protection of rare species.

  • 180. Tabor, J.
    et al.
    Griep, Yannick
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. University of Calgary, Canada.
    Collins, R.
    Mychasiuk, R.
    Investigating the Neurological Correlates of Workplace Deviance Using a Rodent Model of Extinction2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 17316Article in journal (Refereed)
    Abstract [en]

    Employee deviance and time theft is an expensive and pervasive workplace problem. Research indicates that a primary reason employees engage in deviant behaviour is the perception of injustice often associated with psychological contract breach (i.e., broken promises). This study used a rodent model to mimic said experience of broken promises and then examined the subsequent neurophysiological changes that lead to the display of deviant behaviours. Specifically, we generated a psychological contract using a 3 choice serial reaction task, then broke the promise, and finally examined deviant behaviours and neurological correlates. After the broken promise, rats had elevated levels of corticosterone and testosterone, engaged in riskier behaviour, and were more aggressive. The most prominent changes in gene expression were associated with serotonin and stress, and were found in the nucleus accumbens. This study highlights the value of pre-clinical models in the investigation of the theoretical tenants of industrial and organizational psychology.

  • 181.
    Tamm, Sandra
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Nilssone, Gustav
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Schwarz, Johanna
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Lamm, Claus
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Radboud Universiteit, Netherlands.
    Petrovic, Predrag
    Fischer, Håkan
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    The effect of sleep restriction on empathy for pain: An fMRI study in younger and older adults2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 12236Article in journal (Refereed)
    Abstract [en]

    Age and sleep both affect emotional functioning. Since sleep patterns change over the lifespan, we investigated the effects of short sleep and age on empathic responses. In a randomized cross-over experimental design, healthy young and older volunteers (n = 47 aged 20–30 years and n = 39 aged 65–75 years) underwent functional magnetic resonance imaging (fMRI) after normal sleep or night sleep restricted to 3 hours. During fMRI, participants viewed pictures of needles pricking a hand (pain) or Q-tips touching a hand (control), a well-established paradigm to investigate empathy for pain. There was no main effect of sleep restriction on empathy. However, age and sleep interacted so that sleep restriction caused increased unpleasantness in older but not in young participants. Irrespective of sleep condition, older participants showed increased activity in angular gyrus, superior temporal sulcus and temporo-parietal junction compared to young. Speculatively, this could indicate that the older individuals adopted a more cognitive approach in response to others’ pain. Our findings suggest that caution in generalizability across age groups is needed in further studies of sleep on social cognition and emotion.

  • 182.
    Tavakoli, Armin
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Cabello, Adan
    Zukowski, Marek
    Bourennane, Mohamed
    Stockholm University, Faculty of Science, Department of Physics.
    Quantum Clock Synchronization with a Single Qudit2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 7982Article in journal (Refereed)
    Abstract [en]

    Clock synchronization for nonfaulty processes in multiprocess networks is indispensable for a variety of technologies. A reliable system must be able to resynchronize the nonfaulty processes upon some components failing causing the distribution of incorrect or conflicting information in the network. The task of synchronizing such networks is related to Byzantine agreement (BA), which can classically be solved using recursive algorithms if and only if less than one-third of the processes are faulty. Here we introduce a nonrecursive quantum algorithm, based on a quantum solution of the detectable BA, which achieves clock synchronization in the presence of arbitrary many faulty processes by using only a single quantum system.

  • 183.
    Uziela, Karolis
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Shu, Nanjiang
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Wallner, Björn
    Elofsson, Arne
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    ProQ3: Improved model quality assessments using Rosetta energy terms2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 33509Article in journal (Refereed)
    Abstract [en]

    Quality assessment of protein models using no other information than the structure of the model itself has been shown to be useful for structure prediction. Here, we introduce two novel methods, ProQRosFA and ProQRosCen, inspired by the state-of-art method ProQ2, but using a completely different description of a protein model. ProQ2 uses contacts and other features calculated from a model, while the new predictors are based on Rosetta energies: ProQRosFA uses the full-atom energy function that takes into account all atoms, while ProQRosCen uses the coarse-grained centroid energy function. The two new predictors also include residue conservation and terms corresponding to the agreement of a model with predicted secondary structure and surface area, as in ProQ2. We show that the performance of these predictors is on par with ProQ2 and significantly better than all other model quality assessment programs. Furthermore, we show that combining the input features from all three predictors, the resulting predictor ProQ3 performs better than any of the individual methods. ProQ3, ProQRosFA and ProQRosCen are freely available both as a webserver and stand-alone programs at http://proq3.bioinfo.se/.

  • 184.
    Verschut, Thomas A.
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Carlsson, Mikael A.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Anderson, Peter
    Hambäck, Peter A.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Sensory mutations in Drosophila melanogaster influence associational effects between resources during oviposition2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 9352Article in journal (Refereed)
    Abstract [en]

    Neighboring resources can affect insect oviposition behavior when the complexity of sensory information obscures information about host resource availability in heterogeneous resource patches. These effects are referred to as associational effects and are hypothesized to occur through constraints in the sensory processing of the insect during host search, resulting into suboptimal resource use. Because the possibilities to study these constraints on naturally occurring animals are limited, we instead used sensory mutants of Drosophila melanogaster to determine the importance of sensory information in the occurrence of associational effects. We found that oviposition was mainly governed by non-volatile chemical cues and less by volatile cues. Moreover, the loss of gustatory sensilla resulted in random resource selection and eliminated associational effects. In conclusion, our study shows that associational effects do not necessarily depend on constraints in the sensory evaluation of resource quality, but may instead be a direct consequence of distinctive selection behavior between different resources at small scales.

  • 185.
    Vilhjálmsdóttir, Jóhanna
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Gennis, Robert B.
    Brzezinski, Peter
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    The electron distribution in the activated state of cytochrome c oxidase2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 7502Article in journal (Refereed)
    Abstract [en]

    Cytochrome c oxidase catalyzes reduction of O-2 to H2O at a catalytic site that is composed of a copper ion and heme group. The reaction is linked to translocation of four protons across the membrane for each O-2 reduced to water. The free energy associated with electron transfer to the catalytic site is unequal for the four electron-transfer events. Most notably, the free energy associated with reduction of the catalytic site in the oxidized cytochrome c oxidase (state O) is not sufficient for proton pumping across the energized membrane. Yet, this electron transfer is mechanistically linked to proton pumping. To resolve this apparent discrepancy, a high-energy oxidized state (denoted O-H) was postulated and suggested to be populated only during catalytic turnover. The difference between states O and O-H was suggested to be manifested in an elevated midpoint potential of Cu-B in the latter. This proposal predicts that one-electron reduction of cytochrome c oxidase after its oxidation would yield re-reduction of essentially only Cu-B. Here, we investigated this process and found similar to 5% and similar to 6% reduction of heme a(3) and Cu-B, respectively, i.e. the apparent redox potentials for heme a(3) and CuB are lower than that of heme a.

  • 186.
    Vilhjálmsdóttir, Jóhanna
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Johansson, Ann-Louise
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Brzezinski, Peter
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Structural Changes and Proton Transfer in Cytochrome c Oxidase2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 12047Article in journal (Refereed)
    Abstract [en]

    In cytochrome c oxidase electron transfer from cytochrome c to O-2 is linked to transmembrane proton pumping, which contributes to maintaining a proton electrochemical gradient across the membrane. The mechanism by which cytochrome c oxidase couples the exergonic electron transfer to the endergonic proton translocation is not known, but it presumably involves local structural changes that control the alternating proton access to the two sides of the membrane. Such redox-induced structural changes have been observed in X-ray crystallographic studies at residues 423-425 ( in the R. sphaeroides oxidase), located near heme a. The aim of the present study is to investigate the functional effects of these structural changes on reaction steps associated with proton pumping. Residue Ser425 was modified using site-directed mutagenesis and time-resolved spectroscopy was used to investigate coupled electron-proton transfer upon reaction of the oxidase with O2. The data indicate that the structural change at position 425 propagates to the D proton pathway, which suggests a link between redox changes at heme a and modulation of intramolecular proton-transfer rates.

  • 187.
    Wallin, Cecilia
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Sholts, Sabrina B.
    Österlund, Nicklas
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Luo, Jinghui
    Jarvet, Jüri
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. The National Institute of Chemical Physics and Biophysics, Estonia.
    Roos, Per M.
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Gräslund, Astrid
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Wärmländer, Sebastian K. T. S.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Alzheimer's disease and cigarette smoke components: effects of nicotine, PAHs, and Cd(II), Cr(III), Pb(II), Pb(IV) ions on amyloid-beta peptide aggregation2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 14423Article in journal (Refereed)
    Abstract [en]

    Cigarette smoking is a significant risk factor for Alzheimer’s disease (AD), which is associated with extracellular brain deposits of amyloid plaques containing aggregated amyloid-β (Aβ) peptides. Aβ aggregation occurs via multiple pathways that can be influenced by various compounds. Here, we used AFM imaging and NMR, fluorescence, and mass spectrometry to monitor in vitro how Aβ aggregation is affected by the cigarette-related compounds nicotine, polycyclic aromatic hydrocarbons (PAHs) with one to five aromatic rings, and the metal ions Cd(II), Cr(III), Pb(II), and Pb(IV). All PAHs and metal ions modulated the Aβ aggregation process. Cd(II), Cr(III), and Pb(II) ions displayed general electrostatic interactions with Aβ, whereas Pb(IV) ions showed specific transient binding coordination to the N-terminal Aβ segment. Thus, Pb(IV) ions are especially prone to interact with Aβ and affect its aggregation. While Pb(IV) ions affected mainly Aβ dimer and trimer formation, hydrophobic toluene mainly affected formation of larger aggregates such as tetramers. The uncharged and hydrophilic nicotine molecule showed no direct interactions with Aβ, nor did it affect Aβ aggregation. Our Aβ interaction results suggest a molecular rationale for the higher AD prevalence among smokers, and indicate that certain forms of lead in particular may constitute an environmental risk factor for AD.

  • 188. Westerbom, Mats
    et al.
    Lappalainen, Antti
    Mustonen, Olli
    Norkko, Alf
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. Tvärminne Zoological Station, Finland.
    Trophic overlap between expanding and contracting fish predators in a range margin undergoing change2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 7895Article in journal (Refereed)
    Abstract [en]

    Climate change is predicted to cause a freshening of the Baltic Sea, facilitating range expansions of freshwater species and contractions of marine. Resident marine flounders (Platichthys flesus) and expansive freshwater roach (Rutilus rutilus) are dominant consumers in the Baltic Sea sublittoral where they occur in partial sympatry. By comparing patterns of resource use by flounders and roach along a declining resource gradient of blue mussels (Mytilus trossulus) our aim was to explore predator functional responses and the degree of trophic overlap. Understanding the nature of density-dependent prey acquisition has important implications for predicting population dynamics of both predators and their shared prey. Results showed a highly specialized diet for both species, high reliance on blue mussels throughout the range, similar prey size preference and high trophic overlap. Highest overlap occurred where blue mussels were abundant but overlap was also high where they were scarce. Our results highlight the importance of a single food item - the blue mussel - for both species, likely promoting high population size and range expansion of roach. Findings also suggest that range expansion of roach may have a top-down structuring force on mussels that differ in severity and location from that originating from resident flounders.

  • 189. Wikström, Sverre
    et al.
    Lindh, Christian H.
    Shu, Huan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Karlstad University, Sweden.
    Bornehag, Carl-Gustaf
    Early pregnancy serum levels of perfluoroalkyl substances and risk of preeclampsia in Swedish women2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 9179Article in journal (Refereed)
    Abstract [en]

    Preeclampsia is a major cause of maternal and fetal morbidity. Emerging research shows an association with environmental exposures. The present aim was to investigate associations between early pregnancy serum levels of perfluoroalkyl substances (PFAS) and preeclampsia. Within the Swedish SELMA study, eight PFAS were measured at median 10 gestational weeks and cases of preeclampsia were postnatally identified from registers. Associations between individual PFAS and preeclampsia were assessed, adjusting for parity, age, weight and smoking. Out of 1,773 women in the study group, 64 ( 3.6%), developed preeclampsia. A doubling of PFOS and PFNA exposure, corresponding to an inter-quartile increase, was associated with an increased risk for preeclampsia of about 38-53% respectively. Serum PFOS within the highest quartile was associated with an odds ratio of 2.68 ( CI 95%: 1.17-6.12), equal to the increased risk associated with nulliparity, when compared to exposure in the first quartile. The same associations were identified, although with higher risk estimates, in analyses restricted to nulliparous women. For other PFAS, there were no associations. In conclusion and consistent with limited previous research only on PFOS, increasing serum levels of PFOS and PFNA during early pregnancy were associated with a clinically relevant risk of preeclampsia, adjusting for established confounders.

  • 190. Wild, Birgit
    et al.
    Gentsch, Norman
    Capek, Petr
    Diakova, Katerina
    Alves, Ricardo J. Eloy
    Barta, Jiri
    Gittel, Antje
    Hugelius, Gustaf
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Knoltsch, Anna
    Kuhry, Peter
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Lashchinskiy, Nikolay
    Mikutta, Robert
    Palmtag, Juri
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Schleper, Christa
    Schnecker, Jörg
    Shibistova, Olga
    Takriti, Mounir
    Torsvik, Vigdis L.
    Urich, Tim
    Watzka, Margarete
    Santruckova, Hana
    Guggenberger, Georg
    Richter, Andreas
    Plant-derived compounds stimulate the decomposition of organic matter in arctic permafrost soils2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 25607Article in journal (Refereed)
    Abstract [en]

    Arctic ecosystems are warming rapidly, which is expected to promote soil organic matter (SOM) decomposition. In addition to the direct warming effect, decomposition can also be indirectly stimulated via increased plant productivity and plant-soil C allocation, and this so called priming effect might significantly alter the ecosystem C balance. In this study, we provide first mechanistic insights into the susceptibility of SOM decomposition in arctic permafrost soils to priming. By comparing 119 soils from four locations across the Siberian Arctic that cover all horizons of active layer and upper permafrost, we found that an increased availability of plant-derived organic C particularly stimulated decomposition in subsoil horizons where most of the arctic soil carbon is located. Considering the 1,035 Pg of arctic soil carbon, such an additional stimulation of decomposition beyond the direct temperature effect can accelerate net ecosystem C losses, and amplify the positive feedback to global warming.

  • 191. Wohlfarth, Carolin
    et al.
    Schmitteckert, Stefanie
    Härtle, Janina D.
    Houghton, Lesley A.
    Dweep, Harsh
    Fortea, Marina
    Assadi, Ghazaleh
    Braun, Alexander
    Mederer, Tanja
    Pöhner, Sarina
    Becker, Philip P.
    Fischer, Christine
    Granzow, Martin
    Mönnikes, Hubert
    Mayer, Emeran A.
    Sayuk, Gregory
    Boeckxstaens, Guy
    Wouters, Mira M.
    Simrén, Magnus
    Lindberg, Greger
    Ohlsson, Bodil
    Schmidt, Peter Thelin
    Dlugosz, Aldona
    Agreus, Lars
    Andreasson, Anna
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    D'Amato, Mauro
    Burwinkel, Barbara
    Bermejo, Justo Lorenzo
    Röth, Ralph
    Lasitschka, Felix
    Vicario, Maria
    Metzger, Marco
    Santos, Javier
    Rappold, Gudrun A.
    Martinez, Cristina
    Niesler, Beate
    miR-16 and miR-103 impact 5-HT4 receptor signalling and correlate with symptom profile in irritable bowel syndrome2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 14680Article in journal (Refereed)
    Abstract [en]

    Irritable bowel syndrome (IBS) is a gut-brain disorder involving alterations in intestinal sensitivity and motility. Serotonin 5-HT4 receptors are promising candidates in IBS pathophysiology since they regulate gut motor function and stool consistency, and targeted 5-HT4R selective drug intervention has been proven beneficial in subgroups of patients. We identified a single nucleotide polymorphism (SNP) (rs201253747) c.*61 T > C within the 5-HT4 receptor gene HTR4 to be predominantly present in diarrhoea-IBS patients (IBS-D). It affects a binding site for the miR-16 family and miR-103/miR-107 within the isoforms HTR4b/i and putatively impairs HTR4 expression. Subsequent miRNA-profiling revealed downregulation of miR-16 and miR-103 in the jejunum of IBS-D patients correlating with symptoms. In vitro assays confirmed expression regulation via three 3'UTR binding sites. The novel isoform HTR4b_2 lacking two of the three miRNA binding sites escapes miR-16/103/107 regulation in SNP carriers. We provide the first evidence that HTR4 expression is fine-tuned by miRNAs, and that this regulation is impaired either by the SNP c.*61 T > C or by diminished levels of miR-16 and miR-103 suggesting that HTR4 might be involved in the development of IBS-D.

  • 192. Wu, Zhendong
    et al.
    Hugelius, Gustaf
    Stockholm University, Faculty of Science, Department of Physical Geography. Stanford University, USA.
    Luo, Yiqi
    Smith, Benjamin
    Xia, Jianyang
    Fensholt, Rasmus
    Lehsten, Veiko
    Ahlström, Anders
    Approaching the potential of model-data comparisons of global land carbon storage2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 3367Article in journal (Refereed)
    Abstract [en]

    Carbon storage dynamics in vegetation and soil are determined by the balance of carbon influx and turnover. Estimates of these opposing fluxes differ markedly among different empirical datasets and models leading to uncertainty and divergent trends. To trace the origin of such discrepancies through time and across major biomes and climatic regions, we used a model-data fusion framework. The framework emulates carbon cycling and its component processes in a global dynamic ecosystem model, LPJ-GUESS, and preserves the model-simulated pools and fluxes in space and time. Thus, it allows us to replace simulated carbon influx and turnover with estimates derived from empirical data, bringing together the strength of the model in representing processes, with the richness of observational data informing the estimations. The resulting vegetation and soil carbon storage and global land carbon fluxes were compared to independent empirical datasets. Results show model-data agreement comparable to, or even better than, the agreement between independent empirical datasets. This suggests that only marginal improvement in land carbon cycle simulations can be gained from comparisons of models with current-generation datasets on vegetation and soil carbon. Consequently, we recommend that model skill should be assessed relative to reference data uncertainty in future model evaluation studies.

  • 193. Xi, Xinqiang
    et al.
    Yang, Yangheshan
    Yang, Xiaocheng
    Nylin, Soren
    Stockholm University, Faculty of Science, Department of Zoology.
    Eisenhauer, Nico
    Sun, Shucun
    Differential responses of body growth to artificial warming between parasitoids and hosts and the consequences for plant seed damage2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 15472Article in journal (Refereed)
    Abstract [en]

    Temperature increase may disrupt trophic interactions by differentially changing body growth of the species involved. In this study, we tested whether the response of body growth to artificial warming (similar to 2.2 degrees C) of a solitary koinobiont endo-parasitoid wasp (Pteromalus albipennis, Hymenoptera: Pteromalidae) differed from its main host tephritid fly (Tephritis femoralis, Diptera: Tephritidae; pre-dispersal seed predator), and whether the plant seed damage caused by wasp-parasitized and unparasitized maggots (larval flies) were altered by warming. In contrast to the significant and season-dependent effects of warming on body growth of the host tephritid fly reported in one of our previous studies, the effect of artificial warming on body growth was non-significant on the studied wasp. Moreover, the warming effect on seed damage due to unparasitized maggots was significant and varied with season, but the damage by parasitized maggots was not altered by warming. Distinct responses of body growth to warming between parasitoids studied here and hosts assessed in a previous study indicate that temperature increase may differentially affect life history traits of animals along food chains, which is likely to affect trophic interactions.

  • 194. Xie, Xueshu
    et al.
    Backman, Daniel
    Lebedev, Albert T.
    Artaev, Viatcheslav B.
    Jiang, Liying
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Zubarev, Roman A.
    Primordial soup was edible: abiotically produced Miller-Urey mixture supports bacterial growth2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 14338Article in journal (Refereed)
    Abstract [en]

    Sixty years after the seminal Miller-Urey experiment that abiotically produced a mixture of racemized amino acids, we provide a definite proof that this primordial soup, when properly cooked, was edible for primitive organisms. Direct admixture of even small amounts of Miller-Urey mixture strongly inhibits E. coli bacteria growth due to the toxicity of abundant components, such as cyanides. However, these toxic compounds are both volatile and extremely reactive, while bacteria are highly capable of adaptation. Consequently, after bacterial adaptation to a mixture of the two most abundant abiotic amino acids, glycine and racemized alanine, dried and reconstituted MU soup was found to support bacterial growth and even accelerate it compared to a simple mixture of the two amino acids. Therefore, primordial Miller-Urey soup was perfectly suitable as a growth media for early life forms.

  • 195. Yan, Caiqing
    et al.
    Zheng, Mei
    Bosch, Carme
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Andersson, August
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Desyaterik, Yury
    Sullivan, Amy P.
    Collett, Jeffrey L.
    Zhao, Bin
    Wang, Shuxiao
    He, Kebin
    Gustafsson, Örjan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Important fossil source contribution to brown carbon in Beijing during winter2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 43182Article in journal (Refereed)
    Abstract [en]

    Organic aerosol (OA) constitutes a substantial fraction of fine particles and affects both human health and climate. It is becoming clear that OA absorbs light substantially (hence termed Brown Carbon, BrC), adding uncertainties to global aerosol radiative forcing estimations. The few current radiative-transfer and chemical-transport models that include BrC primarily consider sources from biogenic and biomass combustion. However, radiocarbon fingerprinting here clearly indicates that light-absorbing organic carbon in winter Beijing, the capital of China, is mainly due to fossil sources, which contribute the largest part to organic carbon (OC, 67 +/- 3%) and its sub-constituents (water-soluble OC, WSOC: 54 +/- 4%, and water-insoluble OC, WIOC: 73 +/- 3%). The dual-isotope (Delta C-14/delta C-13) signatures, organic molecular tracers and Beijing-tailored emission inventory identify that this fossil source is primarily from coal combustion activities in winter, especially from the residential sector. Source testing on Chinese residential coal combustion provides direct evidence that intensive coal combustion could contribute to increased light-absorptivity of ambient BrC in Beijing winter. Coal combustion is an important source to BrC in regions such as northern China, especially during the winter season. Future modeling of OA radiative forcing should consider the importance of both biomass and fossil sources.

  • 196. Yang, Cheng-En
    et al.
    Mao, Jiafu
    Hoffman, Forrest M.
    Ricciuto, Daniel M.
    Fu, Joshua S.
    Jones, Chris D.
    Thurner, Martin
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Uncertainty Quantification of Extratropical Forest Biomass in CMIP5 Models over the Northern Hemisphere2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 10962Article in journal (Refereed)
    Abstract [en]

    Simplified representations of processes influencing forest biomass in Earth system models (ESMs) contribute to large uncertainty in projections. We evaluate forest biomass from eight ESMs outputs archived in the Coupled Model Intercomparison Project Phase 5 (CMIP5) using the biomass data synthesized from radar remote sensing and ground-based observations across northern extratropical latitudes. ESMs exhibit large biases in the forest distribution, forest fraction, and mass of carbon pools that contribute to uncertainty in forest total biomass (biases range from -20 Pg C to 135 Pg C). Forest total biomass is primarily positively correlated with precipitation variations, with surface temperature becoming equally important at higher latitudes, in both simulations and observations. Relatively small differences in forest biomass between the pre-industrial period and the contemporary period indicate uncertainties in forest biomass were introduced in the pre-industrial model equilibration (spin-up), suggesting parametric or structural model differences are a larger source of uncertainty than differences in transient responses. Our findings emphasize the importance of improved (1) models of carbon allocation to biomass compartments, (2) distribution of vegetation types in models, and (3) reproduction of pre-industrial vegetation conditions, in order to reduce the uncertainty in forest biomass simulated by ESMs.

  • 197. Yang, Haijun
    et al.
    Zhao, Yingying
    Liu, Zhengyu
    Li, Qing
    He, Feng
    Zhang, Qiong
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Heat Transport Compensation in Atmosphere and Ocean over the Past 22,000 Years2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 16661Article in journal (Refereed)
    Abstract [en]

    The Earth's climate has experienced dramatic changes over the past 22,000 years; however, the total meridional heat transport (MHT) of the climate system remains stable. A 22,000-year-long simulation using an ocean-atmosphere coupled model shows that the changes in atmosphere and ocean MHT are significant but tend to be out of phase in most regions, mitigating the total MHT change, which helps to maintain the stability of the Earth's overall climate. A simple conceptual model is used to understand the compensation mechanism. The simple model can reproduce qualitatively the evolution and compensation features of the MHT over the past 22,000 years. We find that the global energy conservation requires the compensation changes in the atmosphere and ocean heat transports. The degree of compensation is mainly determined by the local climate feedback between surface temperature and net radiation flux at the top of the atmosphere. This study suggests that an internal mechanism may exist in the climate system, which might have played a role in constraining the global climate change over the past 22,000 years.

  • 198. Yasui, Takao
    et al.
    Ogawa, Kensuke
    Kaji, Noritada
    Nilsson, Mats
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Ajiri, Taiga
    Tokeshi, Manabu
    Horiike, Yasuhiro
    Baba, Yoshinobu
    Label-free detection of real-time DNA amplification using a nanofluidic diffraction grating2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 31642Article in journal (Refereed)
    Abstract [en]

    Quantitative DNA amplification using fluorescence labeling has played an important role in the recent, rapid progress of basic medical and molecular biological research. Here we report a label-free detection of real-time DNA amplification using a nanofluidic diffraction grating. Our detection system observed intensity changes during DNA amplification of diffracted light derived from the passage of a laser beam through nanochannels embedded in a microchannel. Numerical simulations revealed that the diffracted light intensity change in the nanofluidic diffraction grating was attributed to the change of refractive index. We showed the first case reported to date for label-free detection of real-time DNA amplification, such as specific DNA sequences from tubercle bacilli (TB) and human papillomavirus (HPV). Since our developed system allows quantification of the initial concentration of amplified DNA molecules ranging from 1 fM to 1 pM, we expect that it will offer a new strategy for developing fundamental techniques of medical applications.

  • 199. Yman, Victor
    et al.
    White, Michael T.
    Rono, Josea
    Arca, Bruno
    Osier, Faith H.
    Troye-Blomberg, Marita
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Boström, Stephanie
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Ronca, Raffaele
    Rooth, Ingegerd
    Färnert, Anna
    Antibody acquisition models: A new tool for serological surveillance of malaria transmission intensity2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 19472Article in journal (Refereed)
    Abstract [en]

    Serology has become an increasingly important tool for the surveillance of a wide range of infectious diseases. It has been particularly useful to monitor malaria transmission in elimination settings where existing metrics such as parasite prevalence and incidence of clinical cases are less sensitive. Seroconversion rates, based on antibody prevalence to Plasmodium falciparum asexual blood-stage antigens, provide estimates of transmission intensity that correlate with entomological inoculation rates but lack precision in settings where seroprevalence is still high. Here we present a new and widely applicable method, based on cross-sectional data on individual antibody levels. We evaluate its use as a sero-surveillance tool in a Tanzanian setting with declining malaria prevalence. We find that the newly developed mathematical models produce more precise estimates of transmission patterns, are robust in high transmission settings and when sample sizes are small, and provide a powerful tool for serological evaluation of malaria transmission intensity.

  • 200.
    Yuan, Ning
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Swedish University of Agricultural Sciences, Sweden.
    Church, Tamara L.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Brandt, Erik G.
    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).
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bernin, Diana
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Chalmers University, Sweden.
    Insights into Functionalization of Metal-Organic Frameworks Using In Situ NMR Spectroscopy2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 17530Article in journal (Refereed)
    Abstract [en]

    Postsynthetic reactions of metal-organic frameworks (MOFs) are versatile tools for producing functional materials, but the methods of evaluating these reactions are cumbersome and destructive. Here we demonstrate and validate the use of in situ NMR spectroscopy of species in the liquid state to examine solvent-assisted ligand exchange (SALE) and postsynthetic modification (PSM) reactions of metal-organic frameworks. This technique allows functionalization to be monitored over time without decomposing the product for analysis, which simplifies reaction screening. In the case of SALE, both the added ligand and the ligand leaving the framework can be observed. We demonstrate this in situ method by examining SALE and PSM reactions of the robust zirconium MOF UiO-67 as well as SALE with the aluminum MOF DUT-5. In situ NMR spectroscopy provided insights into the reactions studied, and we expect that future studies using this method will permit the examination of a variety of MOF-solute reactions.

12345 151 - 200 of 207
CiteExportLink to result list
Permanent link
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