| 1. |
- Abbafati, Cristiana, et al.
(författare)
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- 2020
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Santangelo, James S., et al.
(författare)
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Global urban environmental change drives adaptation in white clover
- 2022
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 375
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Tidskriftsartikel (refereegranskat)abstract
- Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural dines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale.
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| 3. |
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| 4. |
- Bais, A. F., et al.
(författare)
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Environmental effects of ozone depletion, UV radiation and interactions with climate change: UNEP Environmental Effects Assessment Panel, update 2017
- 2018
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Ingår i: Photochemical & Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-905X .- 1474-9092. ; 17:2, s. 127-179
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Tidskriftsartikel (refereegranskat)abstract
- The Environmental Effects Assessment Panel (EEAP) is one of three Panels of experts that inform the Parties to the Montreal Protocol. The EEAP focuses on the effects of UV radiation on human health, terrestrial and aquatic ecosystems, air quality, and materials, as well as on the interactive effects of UV radiation and global climate change. When considering the effects of climate change, it has become clear that processes resulting in changes in stratospheric ozone are more complex than previously held. Because of the Montreal Protocol, there are now indications of the beginnings of a recovery of stratospheric ozone, although the time required to reach levels like those before the 1960s is still uncertain, particularly as the effects of stratospheric ozone on climate change and vice versa, are not yet fully understood. Some regions will likely receive enhanced levels of UV radiation, while other areas will likely experience a reduction in UV radiation as ozone- and climate-driven changes affect the amounts of UV radiation reaching the Earth's surface. Like the other Panels, the EEAP produces detailed Quadrennial Reports every four years; the most recent was published as a series of seven papers in 2015 (Photochem. Photobiol. Sci., 2015, 14, 1-184). In the years in between, the EEAP produces less detailed and shorter Update Reports of recent and relevant scientific findings. The most recent of these was for 2016 (Photochem. Photobiol. Sci., 2017, 16, 107-145). The present 2017 Update Report assesses some of the highlights and new insights about the interactive nature of the direct and indirect effects of UV radiation, atmospheric processes, and climate change. A full 2018 Quadrennial Assessment, will be made available in 2018/2019.
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| 5. |
- Bylander, Jonas, 1978, et al.
(författare)
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Noise spectroscopy through dynamical decoupling with a superconducting flux qubit
- 2011
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Ingår i: Nature Physics. - : Springer Science and Business Media LLC. - 1745-2481 .- 1745-2473. ; 7:7, s. 565-570
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Tidskriftsartikel (refereegranskat)abstract
- Quantum coherence in natural and artificial spin systems is fundamental to applications ranging from quantum information science to magnetic-resonance imaging and identification. Several multipulse control sequences targeting generalized noise models have been developed to extend coherence by dynamically decoupling a spin system from its noisy environment. In any particular implementation, however, the efficacy of these methods is sensitive to the specific frequency distribution of the noise, suggesting that these same pulse sequences could also be used to probe the noise spectrum directly. Here we demonstrate noise spectroscopy by means of dynamical decoupling using a superconducting qubit with energy-relaxation time T1 =12 μs. We first demonstrate that dynamical decoupling improves the coherence time T 2 in this system up to the T2 =2 T1 limit (pure dephasing times exceeding 100 μs), and then leverage its filtering properties to probe the environmental noise over a frequency (f) range 0.2-20 MHz, observing a 1/fα distribution with α
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| 6. |
- Gustavsson, S., et al.
(författare)
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Driven dynamics and rotary echo of a qubit tunably coupled to a harmonic oscillator
- 2012
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 108:17, s. 170503-
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the driven dynamics of a superconducting flux qubit that is tunably coupled to a microwave resonator. We find that the qubit experiences an oscillating field mediated by off-resonant driving of the resonator, leading to strong modifications of the qubit Rabi frequency. This opens an additional noise channel, and we find that low-frequency noise in the coupling parameter causes a reduction of the coherence time during driven evolution. The noise can be mitigated with the rotary-echo pulse sequence, which, for driven systems, is analogous to the Hahn-echo sequence. © 2012 American Physical Society.
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| 7. |
- Rader, Romina, et al.
(författare)
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Non-bee insects are important contributors to global crop pollination.
- 2016
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 113:1, s. 146-151
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Tidskriftsartikel (refereegranskat)abstract
- Wild and managed bees are well documented as effective pollinators of global crops of economic importance. However, the contributions by pollinators other than bees have been little explored despite their potential to contribute to crop production and stability in the face of environmental change. Non-bee pollinators include flies, beetles, moths, butterflies, wasps, ants, birds, and bats, among others. Here we focus on non-bee insects and synthesize 39 field studies from five continents that directly measured the crop pollination services provided by non-bees, honey bees, and other bees to compare the relative contributions of these taxa. Non-bees performed 25-50% of the total number of flower visits. Although non-bees were less effective pollinators than bees per flower visit, they made more visits; thus these two factors compensated for each other, resulting in pollination services rendered by non-bees that were similar to those provided by bees. In the subset of studies that measured fruit set, fruit set increased with non-bee insect visits independently of bee visitation rates, indicating that non-bee insects provide a unique benefit that is not provided by bees. We also show that non-bee insects are not as reliant as bees on the presence of remnant natural or seminatural habitat in the surrounding landscape. These results strongly suggest that non-bee insect pollinators play a significant role in global crop production and respond differently than bees to landscape structure, probably making their crop pollination services more robust to changes in land use. Non-bee insects provide a valuable service and provide potential insurance against bee population declines.
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| 8. |
- Yan, F., et al.
(författare)
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Spectroscopy of low-frequency noise and its temperature dependence in a superconducting qubit
- 2012
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 85:17, s. 174521-
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Tidskriftsartikel (refereegranskat)abstract
- We report a direct measurement of the low-frequency noise spectrum in a superconducting flux qubit. Our method uses the noise sensitivity of a free-induction Ramsey interference experiment, comprising free evolution in the presence of noise for a fixed period of time followed by single-shot qubit-state measurement. Repeating this procedure enables Fourier-transform noise spectroscopy with access to frequencies up to the achievable repetition rate, a regime relevant to dephasing in ensemble-averaged time-domain measurements such as Ramsey interferometry. Rotating the qubit's quantization axis allows us to measure two types of noise: effective flux noise and effective critical-current or charge noise. For both noise sources, we observe that the very same 1/f-type power laws measured at considerably higher frequencies (0.2-20 MHz) are consistent with the noise in the 0.01-100-Hz range measured here. We find no evidence of temperature dependence of the noises over 65-200 mK, and also no evidence of time-domain correlations between the two noises. These methods and results are pertinent to the dephasing of all superconducting qubits. © 2012 American Physical Society.
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| 9. |
- Bennett, Deborah, et al.
(författare)
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Project TENDR : Targeting Environmental Neuro-Developmental Risks. The TENDR Consensus Statement
- 2016
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Ingår i: Journal of Environmental Health Perspectives. - : National Institute of Environmental Health Science. - 0091-6765 .- 1552-9924. ; 124:7, s. A118-A122
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Tidskriftsartikel (refereegranskat)abstract
- Children in America today are at an unacceptably high risk of developing neurodevelopmental disorders that affect the brain and nervous system including autism, attention deficit hyperactivity disorder, intellectual disabilities, and other learning and behavioral disabilities. These are complex disorders with multiple causes-genetic, social, and environmental. The contribution of toxic chemicals to these disorders can be prevented. Approach: Leading scientific and medical experts, along with children's health advocates, came together in 2015 under the auspices of Project TENDR: Targeting Environmental Neuro-Developmental Risks to issue a call to action to reduce widespread exposures to chemicals that interfere with fetal and children's brain development. Based on the available scientific evidence, the TENDR authors have identified prime examples of toxic chemicals and pollutants that increase children's risks for neurodevelopmental disorders. These include chemicals that are used extensively in consumer products and that have become widespread in the environment. Some are chemicals to which children and pregnant women are regularly exposed, and they are detected in the bodies of virtually all Americans in national surveys conducted by the U.S. Centers for Disease Control and Prevention. The vast majority of chemicals in industrial and consumer products undergo almost no testing for developmental neurotoxicity or other health effects. Conclusion: Based on these findings, we assert that the current system in the United States for evaluating scientific evidence and making health-based decisions about environmental chemicals is fundamentally broken. To help reduce the unacceptably high prevalence of neurodevelopmental disorders in our children, we must eliminate or significantly reduce exposures to chemicals that contribute to these conditions. We must adopt a new framework for assessing chemicals that have the potential to disrupt brain development and prevent the use of those that may pose a risk. This consensus statement lays the foundation for developing recommendations to monitor, assess, and reduce exposures to neurotoxic chemicals. These measures are urgently needed if we are to protect healthy brain development so that current and future generations can reach their fullest potential.
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| 10. |
- Blundell, MP, et al.
(författare)
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Phosphorylation of WASp is a key regulator of activity and stability in vivo
- 2009
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 106:37, s. 15738-15743
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Tidskriftsartikel (refereegranskat)abstract
- The Wiskott-Aldrich syndrome protein (WASp) is a key cytoskeletal regulator in hematopoietic cells. Covalent modification of a conserved tyrosine by phosphorylation has emerged as an important potential determinant of activity, although the physiological significance remains uncertain. In a murine knockin model, mutation resulting in inability to phosphorylate Y293 (Y293F) mimicked many features of complete WASp-deficiency. Although a phosphomimicking mutant Y293E conferred enhanced actin-polymerization, the cellular phenotype was similar due to functional dysregulation. Furthermore, steady-state levels of Y293E-WASp were markedly reduced compared to wild-type WASp and Y293F-WASp, although partially recoverable by treatment of cells with proteasome inhibitors. Consequently, tyrosine phosphorylation plays a critical role in normal activation of WASp in vivo, and is indispensible for multiple tasks including proliferation, phagocytosis, chemotaxis, and assembly of adhesion structures. Furthermore, it may target WASp for proteasome-mediated degradation, thereby providing a default mechanism for self-limiting stimulation of the Arp2/3 complex.
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| 11. |
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| 12. |
- Foote, Andrew D., et al.
(författare)
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Killer whale genomes reveal a complex history of recurrent admixture and vicariance
- 2019
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Ingår i: Molecular Ecology. - : WILEY. - 0962-1083 .- 1365-294X. ; 28:14, s. 3427-3444
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Tidskriftsartikel (refereegranskat)abstract
- Reconstruction of the demographic and evolutionary history of populations assuming a consensus tree-like relationship can mask more complex scenarios, which are prevalent in nature. An emerging genomic toolset, which has been most comprehensively harnessed in the reconstruction of human evolutionary history, enables molecular ecologists to elucidate complex population histories. Killer whales have limited extrinsic barriers to dispersal and have radiated globally, and are therefore a good candidate model for the application of such tools. Here, we analyse a global data set of killer whale genomes in a rare attempt to elucidate global population structure in a nonhuman species. We identify a pattern of genetic homogenisation at lower latitudes and the greatest differentiation at high latitudes, even between currently sympatric lineages. The processes underlying the major axis of structure include high drift at the edge of species' range, likely associated with founder effects and allelic surfing during postglacial range expansion. Divergence between Antarctic and non-Antarctic lineages is further driven by ancestry segments with up to fourfold older coalescence time than the genome-wide average; relicts of a previous vicariance during an earlier glacial cycle. Our study further underpins that episodic gene flow is ubiquitous in natural populations, and can occur across great distances and after substantial periods of isolation between populations. Thus, understanding the evolutionary history of a species requires comprehensive geographic sampling and genome-wide data to sample the variation in ancestry within individuals.
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| 13. |
- Hjorth Larsen, Ask, et al.
(författare)
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The atomic simulation environment-a Python library for working with atoms
- 2017
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 0953-8984 .- 1361-648X. ; 29:27
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Forskningsöversikt (refereegranskat)abstract
- The atomic simulation environment (ASE) is a software package written in the Python programming language with the aim of setting up, steering, and analyzing atomistic simulations. In ASE, tasks are fully scripted in Python. The powerful syntax of Python combined with the NumPy array library make it possible to perform very complex simulation tasks. For example, a sequence of calculations may be performed with the use of a simple 'for-loop' construction. Calculations of energy, forces, stresses and other quantities are performed through interfaces to many external electronic structure codes or force fields using a uniform interface. On top of this calculator interface, ASE provides modules for performing many standard simulation tasks such as structure optimization, molecular dynamics, handling of constraints and performing nudged elastic band calculations.
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| 14. |
- Lane, Jeffrey E., et al.
(författare)
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Phenological shifts in North American red squirrels : disentangling the roles of phenotypic plasticity and microevolution
- 2018
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Ingår i: Journal of Evolutionary Biology. - : WILEY. - 1010-061X .- 1420-9101. ; 31:6, s. 810-821
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Tidskriftsartikel (refereegranskat)abstract
- Phenological shifts are the most widely reported ecological responses to climate change, but the requirements to distinguish their causes (i.e. phenotypic plasticity vs. microevolution) are rarely met. To do so, we analysed almost two decades of parturition data from a wild population of North American red squirrels (Tamiasciurus hudsonicus). Although an observed advance in parturition date during the first decade provided putative support for climate change-driven microevolution, a closer look revealed a more complex pattern. Parturition date was heritable [h(2)=0.14 (0.07-0.21 (HPD interval)] and under phenotypic selection [=-0.14 +/- 0.06 (SE)] across the full study duration. However, the early advance reversed in the second decade. Further, selection did not act on the genetic contribution to variation in parturition date, and observed changes in predicted breeding values did not exceed those expected due to genetic drift. Instead, individuals responded plastically to environmental variation, and high food [white spruce (Picea glauca) seed] production in the first decade appears to have produced a plastic advance. In addition, there was little evidence of climate change affecting the advance, as there was neither a significant influence of spring temperature on parturition date or evidence of a change in spring temperatures across the study duration. Heritable traits not responding to selection in accordance with quantitative genetic predictions have long presented a puzzle to evolutionary ecologists. Our results on red squirrels provide empirical support for one potential solution: phenotypic selection arising from an environmental, as opposed to genetic, covariance between the phenotypic trait and annual fitness.
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| 15. |
- Loryan, Irena, Associate Professor (Docent), 1977-, et al.
(författare)
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Unbound Brain-to-Plasma Partition Coefficient, K-p,K-uu,K-brain-a Game Changing Parameter for CNS Drug Discovery and Development
- 2022
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Ingår i: Pharmaceutical research. - : Springer Nature. - 0724-8741 .- 1573-904X. ; 39:7, s. 1321-1341
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Tidskriftsartikel (refereegranskat)abstract
- Purpose More than 15 years have passed since the first description of the unbound brain-to-plasma partition coefficient (K-p,K-uu,K-brain) by Prof. Margareta Hammarlund-Udenaes, which was enabled by advancements in experimental methodologies including cerebral microdialysis. Since then, growing knowledge and data continue to support the notion that the unbound (free) concentration of a drug at the site of action, such as the brain, is the driving force for pharmacological responses. Towards this end, K-p,K-uu,K-brain is the key parameter to obtain unbound brain concentrations from unbound plasma concentrations. Methods To understand the importance and impact of the K-p,K-uu,K-brain concept in contemporary drug discovery and development, a survey has been conducted amongst major pharmaceutical companies based in Europe and the USA. Here, we present the results from this survey which consisted of 47 questions addressing: 1) Background information of the companies, 2) Implementation, 3) Application areas, 4) Methodology, 5) Impact and 6) Future perspectives. Results and conclusions From the responses, it is clear that the majority of the companies (93%) has established a common understanding across disciplines of the concept and utility of K-p,K-uu,K-brain as compared to other parameters related to brain exposure. Adoption of the K-p,K-uu,K-brain concept has been mainly driven by individual scientists advocating its application in the various companies rather than by a top-down approach. Remarkably, 79% of all responders describe the portfolio impact of K-p,K-uu,K-brain implementation in their companies as 'game-changing'. Although most companies (74%) consider the current toolbox for K-p,K-uu,K-brain assessment and its validation satisfactory for drug discovery and early development, areas of improvement and future research to better understand human brain pharmacokinetics/pharmacodynamics translation have been identified.
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| 16. |
- Milner, David S, et al.
(författare)
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A functional bacteria-derived restriction modification system in the mitochondrion of a heterotrophic protist
- 2021
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Ingår i: PLoS Biology. - : Public Library of Science (PLoS). - 1545-7885. ; 19:4
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Tidskriftsartikel (refereegranskat)abstract
- The overarching trend in mitochondrial genome evolution is functional streamlining coupled with gene loss; therefore, gene acquisition by mitochondria is considered to be exceedingly rare. Selfish elements in the form of self-splicing introns occur in many organellar genomes, but the wider diversity of selfish elements, and how they persist in the DNA of organelles, has not been explored. In the mitochondrial genome of a marine heterotrophic katablepharid protist, we identify a functional type II restriction modification (RM) system originating from a horizontal gene transfer (HGT) event involving bacteria related to flavobacteria. This RM system consists of an HpaII-like endonuclease and a cognate cytosine methyltransferase (CM). We demonstrate that these proteins are functional by heterologous expression in both bacterial and eukaryotic cells. These results suggest that a mitochondrial-encoded RM system can function as a toxin-antitoxin selfish element and that such elements could be co-opted by eukaryotic genomes to drive biased organellar inheritance.
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| 17. |
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| 18. |
- Root, Cory M., et al.
(författare)
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A presynaptic gain control mechanism fine-tunes olfactory behavior
- 2008
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Ingår i: Neuron. - 0896-6273. ; 59:2, s. 311-21
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Tidskriftsartikel (refereegranskat)abstract
- Early sensory processing can play a critical role in sensing environmental cues. We have investigated the physiological and behavioral function of gain control at the first synapse of olfactory processing in Drosophila. Olfactory receptor neurons (ORNs) express the GABA(B) receptor (GABA(B)R), and its expression expands the dynamic range of ORN synaptic transmission that is preserved in projection neuron responses. Strikingly, each ORN channel has a unique baseline level of GABA(B)R expression. ORNs that sense the aversive odorant CO(2) do not express GABA(B)Rs and do not have significant presynaptic inhibition. In contrast, pheromone-sensing ORNs express a high level of GABA(B)Rs and exhibit strong presynaptic inhibition. Furthermore, pheromone-dependent mate localization is impaired in flies that lack GABA(B)Rs in specific ORNs. These findings indicate that different olfactory receptor channels employ heterogeneous presynaptic gain control as a mechanism to allow an animal's innate behavioral responses to match its ecological needs.
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| 19. |
- Stoustrup, Peter, et al.
(författare)
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Management of orofacial manifestations of juvenile idiopathic arthritis : Interdisciplinary consensus-based recommendations.
- 2023
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Ingår i: Arthritis & Rheumatology. - : John Wiley & Sons. - 2326-5191 .- 2326-5205. ; 75:1, s. 4-14
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Forskningsöversikt (refereegranskat)abstract
- OBJECTIVES: Involvement of the temporomandibular joint (TMJ) is common in juvenile idiopathic arthritis (JIA). TMJ arthritis can lead to orofacial symptoms, dysfunction and dentofacial deformity with negative impact on quality of life. Management involves interdisciplinary collaboration. No current recommendations exist to guide clinical management.OBJECTIVES: 1) To develop consensus-based interdisciplinary recommendations for management of orofacial manifestations of JIA. 2) To create a future research agenda related to management of TMJ arthritis in children with JIA.METHODS: The recommendations were developed using online surveying of relevant stakeholders, systematic literature review, evidence-informed generation of recommendations during two consensus-meetings, and Delphi study iterations involving external experts. The process included disciplines involved in the care of orofacial manifestations of JIA: Pediatric rheumatology, radiology, orthodontics, oral and maxillofacial surgery, orofacial pain specialists and pediatric dentistry. Recommendations were accepted if agreement was >80% during a final Delphi study.RESULTS: Three overarching management principles and 12 recommendations for interdisciplinary management of orofacial manifestations of JIA were outlined. The 12 recommendations pertained to: diagnosis (n=4), treatment of TMJ arthritis (active TMJ inflammation) (n=2), treatment of TMJ dysfunction and symptoms (n=3), treatment of arthritis-related dentofacial deformity (n=2), and other related aspects to JIA (n=1). Additionally, a future interdisciplinary research agenda was developed.CONCLUSIONS: These are the first interdisciplinary recommendations to guide clinical management of TMJ JIA. The 3 overarching principles and 12 recommendations fill an important gap in current clinical practice. They emphasize the importance of an interdisciplinary approach to diagnosis and management of orofacial manifestations of JIA. This article is protected by copyright. All rights reserved.
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| 20. |
- Stoustrup, Peter, et al.
(författare)
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Standardizing Terminology and Assessment for Orofacial Conditions in Juvenile Idiopathic Arthritis : International, Multidisciplinary Consensus-based Recommendations
- 2019
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Ingår i: Journal of Rheumatology. - : Journal Of Rheumatology Publishing Co., Ltd.. - 0315-162X .- 1499-2752. ; 46:5, s. 518-522
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To propose multidisciplinary, consensus-based, standardization of operational terminology and method of assessment for temporomandibular joint (TMJ) involvement in juvenile idiopathic arthritis (JIA). Methods. Using a sequential expert group-defined terminology and methods-of-assessment approach by (1) establishment of task force, (2) item generation, (3) working group consensus, (4) external expert content validity testing, and (5) multidisciplinary group of experts final Delphi survey consensus. Results. Seven standardized operational terms were defined: TMJ arthritis, TMJ involvement, TMJ arthritis management, dentofacial deformity, TMJ deformity, TMJ symptoms, and TMJ dysfunction. Conclusion. Definition of 7 operational standardized terms provides an optimal platform for communication across healthcare providers involved in JIA-TMJ arthritis management.
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| 21. |
- Vonk, J. E., et al.
(författare)
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Reviews and syntheses : Effects of permafrost thaw on Arctic aquatic ecosystems
- 2015
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 12:23, s. 7129-7167
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Tidskriftsartikel (refereegranskat)abstract
- The Arctic is a water-rich region, with freshwater systems covering about 16% of the northern permafrost landscape. Permafrost thaw creates new freshwater ecosystems, while at the same time modifying the existing lakes, streams, and rivers that are impacted by thaw. Here, we describe the current state of knowledge regarding how permafrost thaw affects lentic (still) and lotic (moving) systems, exploring the effects of both thermokarst (thawing and collapse of ice-rich permafrost) and deepening of the active layer (the surface soil layer that thaws and refreezes each year). Within thermokarst, we further differentiate between the effects of thermokarst in lowland areas vs. that on hillslopes. For almost all of the processes that we explore, the effects of thaw vary regionally, and between lake and stream systems. Much of this regional variation is caused by differences in ground ice content, topography, soil type, and permafrost coverage. Together, these modifying factors determine (i) the degree to which permafrost thaw manifests as thermokarst, (ii) whether thermokarst leads to slumping or the formation of thermokarst lakes, and (iii) the manner in which constituent delivery to freshwater systems is altered by thaw. Differences in thaw-enabled constituent delivery can be considerable, with these modifying factors determining, for example, the balance between delivery of particulate vs. dissolved constituents, and inorganic vs. organic materials. Changes in the composition of thaw-impacted waters, coupled with changes in lake morphology, can strongly affect the physical and optical properties of thermokarst lakes. The ecology of thaw-impacted lakes and streams is also likely to change; these systems have unique microbiological communities, and show differences in respiration, primary production, and food web structure that are largely driven by differences in sediment, dissolved organic matter, and nutrient delivery. The degree to which thaw enables the delivery of dissolved vs. particulate organic matter, coupled with the composition of that organic matter and the morphology and stratification characteristics of recipient systems will play an important role in determining the balance between the release of organic matter as greenhouse gases (CO2 and CH4), its burial in sediments, and its loss downstream. The magnitude of thaw impacts on northern aquatic ecosystems is increasing, as is the prevalence of thaw-impacted lakes and streams. There is therefore an urgent need to quantify how permafrost thaw is affecting aquatic ecosystems across diverse Arctic landscapes, and the implications of this change for further climate warming.
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| 22. |
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| 23. |
- Yan, F., et al.
(författare)
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Rotating-frame relaxation as a noise spectrum analyser of a superconducting qubit undergoing driven evolution
- 2013
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 4, s. 2337-
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Tidskriftsartikel (refereegranskat)abstract
- Gate operations in a quantum information processor are generally realized by tailoring specific periods of free and driven evolution of a quantum system. Unwanted environmental noise, which may in principle be distinct during these two periods, acts to decohere the system and increase the gate error rate. Although there has been significant progress characterizing noise processes during free evolution, the corresponding driven-evolution case is more challenging as the noise being probed is also extant during the characterization protocol. Here we demonstrate the noise spectroscopy (0.1-200 MHz) of a superconducting flux qubit during driven evolution by using a robust spin-locking pulse sequence to measure relaxation (T1ρ) in the rotating frame. In the case of flux noise, we resolve spectral features due to coherent fluctuators, and further identify a signature of the 1 MHz defect in a time-domain spin-echo experiment. The driven-evolution noise spectroscopy complements free-evolution methods, enabling the means to characterize and distinguish various noise processes relevant for universal quantum control. © 2013 Macmillan Publishers Limited. All rights reserved.
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