| 1. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 3. |
- Brownstein, Catherine A., et al.
(författare)
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An international effort towards developing standards for best practices in analysis, interpretation and reporting of clinical genome sequencing results in the CLARITY Challenge
- 2014
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Ingår i: Genome Biology. - : Springer Science and Business Media LLC. - 1465-6906 .- 1474-760X. ; 15:3, s. R53-
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Tidskriftsartikel (refereegranskat)abstract
- Background: There is tremendous potential for genome sequencing to improve clinical diagnosis and care once it becomes routinely accessible, but this will require formalizing research methods into clinical best practices in the areas of sequence data generation, analysis, interpretation and reporting. The CLARITY Challenge was designed to spur convergence in methods for diagnosing genetic disease starting from clinical case history and genome sequencing data. DNA samples were obtained from three families with heritable genetic disorders and genomic sequence data were donated by sequencing platform vendors. The challenge was to analyze and interpret these data with the goals of identifying disease-causing variants and reporting the findings in a clinically useful format. Participating contestant groups were solicited broadly, and an independent panel of judges evaluated their performance. Results: A total of 30 international groups were engaged. The entries reveal a general convergence of practices on most elements of the analysis and interpretation process. However, even given this commonality of approach, only two groups identified the consensus candidate variants in all disease cases, demonstrating a need for consistent fine-tuning of the generally accepted methods. There was greater diversity of the final clinical report content and in the patient consenting process, demonstrating that these areas require additional exploration and standardization. Conclusions: The CLARITY Challenge provides a comprehensive assessment of current practices for using genome sequencing to diagnose and report genetic diseases. There is remarkable convergence in bioinformatic techniques, but medical interpretation and reporting are areas that require further development by many groups.
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| 4. |
- Gutman, Boris A, et al.
(författare)
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A meta-analysis of deep brain structural shape and asymmetry abnormalities in 2,833 individuals with schizophrenia compared with 3,929 healthy volunteers via the ENIGMA Consortium
- 2022
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Ingår i: Human Brain Mapping. - : John Wiley & Sons. - 1065-9471 .- 1097-0193. ; 43:1, s. 352-372
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Tidskriftsartikel (refereegranskat)abstract
- Schizophrenia is associated with widespread alterations in subcortical brain structure. While analytic methods have enabled more detailed morphometric characterization, findings are often equivocal. In this meta-analysis, we employed the harmonized ENIGMA shape analysis protocols to collaboratively investigate subcortical brain structure shape differences between individuals with schizophrenia and healthy control participants. The study analyzed data from 2,833 individuals with schizophrenia and 3,929 healthy control participants contributed by 21 worldwide research groups participating in the ENIGMA Schizophrenia Working Group. Harmonized shape analysis protocols were applied to each site's data independently for bilateral hippocampus, amygdala, caudate, accumbens, putamen, pallidum, and thalamus obtained from T1-weighted structural MRI scans. Mass univariate meta-analyses revealed more-concave-than-convex shape differences in the hippocampus, amygdala, accumbens, and thalamus in individuals with schizophrenia compared with control participants, more-convex-than-concave shape differences in the putamen and pallidum, and both concave and convex shape differences in the caudate. Patterns of exaggerated asymmetry were observed across the hippocampus, amygdala, and thalamus in individuals with schizophrenia compared to control participants, while diminished asymmetry encompassed ventral striatum and ventral and dorsal thalamus. Our analyses also revealed that higher chlorpromazine dose equivalents and increased positive symptom levels were associated with patterns of contiguous convex shape differences across multiple subcortical structures. Findings from our shape meta-analysis suggest that common neurobiological mechanisms may contribute to gray matter reduction across multiple subcortical regions, thus enhancing our understanding of the nature of network disorganization in schizophrenia.
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| 5. |
- Grossmann, Igor, et al.
(författare)
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Insights into the accuracy of social scientists' forecasts of societal change
- 2023
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Ingår i: Nature Human Behaviour. - : Springer Nature. - 2397-3374. ; 7, s. 484-501
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Tidskriftsartikel (refereegranskat)abstract
- How well can social scientists predict societal change, and what processes underlie their predictions? To answer these questions, we ran two forecasting tournaments testing the accuracy of predictions of societal change in domains commonly studied in the social sciences: ideological preferences, political polarization, life satisfaction, sentiment on social media, and gender-career and racial bias. After we provided them with historical trend data on the relevant domain, social scientists submitted pre-registered monthly forecasts for a year (Tournament 1; N = 86 teams and 359 forecasts), with an opportunity to update forecasts on the basis of new data six months later (Tournament 2; N = 120 teams and 546 forecasts). Benchmarking forecasting accuracy revealed that social scientists' forecasts were on average no more accurate than those of simple statistical models (historical means, random walks or linear regressions) or the aggregate forecasts of a sample from the general public (N = 802). However, scientists were more accurate if they had scientific expertise in a prediction domain, were interdisciplinary, used simpler models and based predictions on prior data. How accurate are social scientists in predicting societal change, and what processes underlie their predictions? Grossmann et al. report the findings of two forecasting tournaments. Social scientists' forecasts were on average no more accurate than those of simple statistical models.
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| 6. |
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| 7. |
- Petrov, Dmitry, et al.
(författare)
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Machine Learning for Large-Scale Quality Control of 3D Shape Models in Neuroimaging
- 2017
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Ingår i: Machine learning in medical imaging. MLMI (Workshop). - Cham : Springer International Publishing. ; 10541, s. 371-378
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Tidskriftsartikel (refereegranskat)abstract
- As very large studies of complex neuroimaging phenotypes become more common, human quality assessment of MRI-derived data remains one of the last major bottlenecks. Few attempts have so far been made to address this issue with machine learning. In this work, we optimize predictive models of quality for meshes representing deep brain structure shapes. We use standard vertex-wise and global shape features computed homologously across 19 cohorts and over 7500 human-rated subjects, training kernelized Support Vector Machine and Gradient Boosted Decision Trees classifiers to detect meshes of failing quality. Our models generalize across datasets and diseases, reducing human workload by 30-70%, or equivalently hundreds of human rater hours for datasets of comparable size, with recall rates approaching inter-rater reliability.
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| 8. |
- Anderson, Cynthia M., et al.
(författare)
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Permanent Genetic Resources added to Molecular Ecology Resources Database 1 December 2009-31 January 2010
- 2010
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Ingår i: Molecular Ecology Resources. - : Wiley. - 1755-098X .- 1755-0998. ; 10:3, s. 576-579
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Tidskriftsartikel (refereegranskat)abstract
- This article documents the addition of 220 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Allanblackia floribunda, Amblyraja radiata, Bactrocera cucurbitae, Brachycaudus helichrysi, Calopogonium mucunoides, Dissodactylus primitivus, Elodea canadensis, Ephydatia fluviatilis, Galapaganus howdenae howdenae, Hoplostethus atlanticus, Ischnura elegans, Larimichthys polyactis, Opheodrys vernalis, Pelteobagrus fulvidraco, Phragmidium violaceum, Pistacia vera, and Thunnus thynnus. These loci were cross-tested on the following species: Allanblackia gabonensis, Allanblackia stanerana, Neoceratitis cyanescens, Dacus ciliatus, Dacus demmerezi, Bactrocera zonata, Ceratitis capitata, Ceratitis rosa, Ceratits catoirii, Dacus punctatifrons, Ephydatia mulleri, Spongilla lacustris, Geodia cydonium, Axinella sp., Ischnura graellsii, Ischnura ramburii, Ischnura pumilio, Pistacia integerrima and Pistacia terebinthus.
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| 9. |
- Li, J., et al.
(författare)
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Efficient dye-sensitized solar cells with [copper(6,6′-dimethyl-2,2′-bipyridine)2]2+/1+ redox shuttle
- 2017
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 7:8, s. 4611-4615
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Tidskriftsartikel (refereegranskat)abstract
- The [copper(6,6′-dimethyl-2,2′-bipyridine)2]2+/1+ ([Cu(dmbp)2]2+/1+) redox couple, which possesses a distorted tetragonal geometry of a Cu(i) complex crystal and a distorted tetrahedral coordination geometry of Cu(ii) complex crystal, has been developed as a redox mediator in dye-sensitized solar cells (DSSCs). The energy of loss for dye regeneration was reduced with a very low but sufficient driving force of only 0.11 eV. A distinct increase in open-circuit voltage (VOC) was achieved and a remarkable power conversion efficiency of 10.3% was afforded at 100 mW cm−2 under AM 1.5G condition.
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| 10. |
- Li, L., et al.
(författare)
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Divergence and plasticity shape adaptive potential of the Pacific oyster
- 2018
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Ingår i: Nature Ecology & Evolution. - : Springer Science and Business Media LLC. - 2397-334X. ; 2:11, s. 1751-1760
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Tidskriftsartikel (refereegranskat)abstract
- The interplay between divergence and phenotypic plasticity is critical to our understanding of a species' adaptive potential under rapid climate changes. We investigated divergence and plasticity in natural populations of the Pacific oyster Crassostrea gigas with a congeneric oyster Crassostrea angulata from southern China used as an outgroup. Genome re-sequencing of 371 oysters revealed unexpected genetic divergence in a small area that coincided with phenotypic divergence in growth, physiology, heat tolerance and gene expression across environmental gradients. These findings suggest that selection and local adaptation are pervasive and, together with limited gene flow, influence population structure. Genes showing sequence differentiation between populations also diverged in transcriptional response to heat stress. Plasticity in gene expression is positively correlated with evolved divergence, indicating that plasticity is adaptive and favoured by organisms under dynamic environments. Divergence in heat tolerance-partly through acetylation-mediated energy depression-implies differentiation in adaptive potential. Trade-offs between growth and survival may play an important role in local adaptation of oysters and other marine invertebrates.
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| 11. |
- Yoo, S. J. B., et al.
(författare)
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Spectral phase encoded time spread optical code division multiple access technology for next generation communication networks Invited
- 2007
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Ingår i: Journal of Optical Networking. - 1536-5379. ; 6:10, s. 1210-1227
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Tidskriftsartikel (refereegranskat)abstract
- We overview and summarize the progress of the spectral phase encoded time spreading (SPECTS) optical code division multiple access (O-CDMA) technology. Recent progress included a demonstration of a 320 Gbit/s (32-user x 10 Gbit/s) all-optical passive optical network testbed based on the SPECTS O-CDMA technology and a theoretical prediction of the spectral efficiency at 100% and above. In particular, InP-based integrated photonics allows implementation of SPECTS O-CDMA transmitters and receivers monolithically integrated on a chip. The integrated InP chip technology not only allows robust and compact configurations for practical and low-cost O-CDMA network deployments but also offers code reconfigurations at rapid rates for secure communication applications.
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| 12. |
- Cao, J., et al.
(författare)
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Error-free spectral encoding and decoding operation of InP O-CDMA encoder
- 2006
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Ingår i: 2006 Optical Fiber Communication Conference, and the 2006 National Fiber Optic Engineers Conference. - : IEEE. - 1557528039 - 9781557528032
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Konferensbidrag (refereegranskat)abstract
- We report error-free spectral encoding and decoding operation of an InP monolithic, ultra-compact optical-CDMA encoder/decoder photonic chip pair. The experimental results demonstrate the strong potential for realizing high performance O-CDMA networks with InP micro-systems.
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| 13. |
- Cong, Ronggang, et al.
(författare)
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Optimizing intermediate ecosystem services in agriculture using rules based on landscape composition and configuration indices
- 2016
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Ingår i: Ecological Economics. - : Elsevier BV. - 0921-8009 .- 1873-6106. ; 128, s. 214-223
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Tidskriftsartikel (refereegranskat)abstract
- Important intermediate ecosystem services (ES) such as crop pollination and biological control of pests, which underpin the final ES agricultural yields, are mediated by mobile organisms that depend on availability of habitat and its arrangement in the landscape. It has been suggested that landscape-scale management (LSM) of habitat in a multi-farm setting results in higher provisioning of such ES compared to farm-scale management (FSM). However, to achieve the LSM solution, farmers' land-use decisions need to be coordinated. To this end, we develop rules based on novel landscape composition and configuration indices. We model farmers' interdependencies through ES in an agent-based model (ABM) and optimize land use at both the farm and landscape scales for comparison. Our analysis is based on a simple artificial landscape with homogeneous soil quality and uses crop pollination as an illustrative ecosystem service. We consider habitat configuration at the field scale. Our rules demonstrate that the coordinated solution is characterized by a higher degree of habitat availability and a configuration of habitat that is dispersed rather than agglomerated. We tested these rules over a range of assumptions about ecological parameter values and suggest that such rules could be used to improve governance of ES in agricultural landscapes.
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| 14. |
- Dries, Daniel R., et al.
(författare)
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Loss of Nicastrin from Oligodendrocytes Results in Hypomyelination and Schizophrenia with Compulsive Behavior
- 2016
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 291:22, s. 11647-11656
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Tidskriftsartikel (refereegranskat)abstract
- The biological underpinnings and the pathological lesions of psychiatric disorders are centuries-old questions that have yet to be understood. Recent studies suggest that schizophrenia and related disorders likely have their origins in perturbed neurodevelopment and can result from a large number of common genetic variants or multiple, individually rare genetic alterations. It is thus conceivable that key neurodevelopmental pathways underline the various genetic changes and the still unknown pathological lesions in schizophrenia. Here, we report that mice defective of the nicastrin subunit of gamma-secretase in oligodendrocytes have hypomyelination in the central nervous system. These mice have altered dopamine signaling and display profound abnormal phenotypes reminiscent of schizophrenia. In addition, we identify an association of the nicastrin gene with a human schizophrenia cohort. These observations implicate gamma-secretase and its mediated neurodevelopmental pathways in schizophrenia and provide support for the "myelination hypothesis" of the disease. Moreover, by showing that schizophrenia and obsessive-compulsive symptoms could be modeled in animals wherein a single genetic factor is altered, our work provides a biological basis that schizophrenia with obsessive-compulsive disorder is a distinct subtype of schizophrenia.
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| 15. |
- Fan, Qunping, et al.
(författare)
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10.13% Efficiency All-Polymer Solar Cells Enabled by Improving the Optical Absorption of Polymer Acceptors
- 2020
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Ingår i: Solar RRL. - : Wiley. - 2367-198X. ; 4:6
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Tidskriftsartikel (refereegranskat)abstract
- The limited light absorption capacity for most polymer acceptors hinders the improvement of the power conversion efficiency (PCE) of all-polymer solar cells (all-PSCs). Herein, by simultaneously increasing the conjugation of the acceptor unit and enhancing the electron-donating ability of the donor unit, a novel narrow-bandgap polymer acceptor PF3-DTCO based on an A–D–A-structured acceptor unit ITIC16 and a carbon–oxygen (C–O)-bridged donor unit DTCO is developed. The extended conjugation of the acceptor units from IDIC16 to ITIC16 results in a red-shifted absorption spectrum and improved absorption coefficient without significant reduction of the lowest unoccupied molecular orbital energy level. Moreover, in addition to further broadening the absorption spectrum by the enhanced intramolecular charge transfer effect, the introduction of C–O bridges into the donor unit improves the absorption coefficient and electron mobility, as well as optimizes the morphology and molecular order of active layers. As a result, the PF3-DTCO achieves a higher PCE of 10.13% with a higher short-circuit current density (Jsc) of 15.75 mA cm−2 in all-PSCs compared with its original polymer acceptor PF2-DTC (PCE = 8.95% and Jsc = 13.82 mA cm−2). Herein, a promising method is provided to construct high-performance polymer acceptors with excellent optical absorption for efficient all-PSCs.
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| 16. |
- Fan, Tingting, et al.
(författare)
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Bright circularly polarized soft X-ray high harmonics for X-ray magnetic circular dichroism
- 2015
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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. - 0027-8424 .- 1091-6490. ; 112:46, s. 14206-14211
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 mu m, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantum trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N-4,N-5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform.
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| 17. |
- Kim, Min Seo, et al.
(författare)
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Global burden of peripheral artery disease and its risk factors, 1990-2019 : a systematic analysis for the Global Burden of Disease Study 2019
- 2023
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Ingår i: The Lancet Global Health. - : Elsevier. - 2214-109X. ; 11:10, s. E1553-E1565
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Tidskriftsartikel (refereegranskat)abstract
- Background: Peripheral artery disease is a growing public health problem. We aimed to estimate the global disease burden of peripheral artery disease, its risk factors, and temporospatial trends to inform policy and public measures.Methods: Data on peripheral artery disease were modelled using the Global Burden of Disease, Injuries, and Risk Factors Study (GBD) 2019 database. Prevalence, disability-adjusted life years (DALYs), and mortality estimates of peripheral artery disease were extracted from GBD 2019. Total DALYs and age-standardised DALY rate of peripheral artery disease attributed to modifiable risk factors were also assessed.Findings: In 2019, the number of people aged 40 years and older with peripheral artery disease was 113 million (95% uncertainty interval [UI] 99 center dot 2-128 center dot 4), with a global prevalence of 1 center dot 52% (95% UI 1 center dot 33-1 center dot 72), of which 42 center dot 6% was in countries with low to middle Socio-demographic Index (SDI). The global prevalence of peripheral artery disease was higher in older people, (14 center dot 91% [12 center dot 41-17 center dot 87] in those aged 80-84 years), and was generally higher in females than in males. Globally, the total number of DALYs attributable to modifiable risk factors in 2019 accounted for 69 center dot 4% (64 center dot 2-74 center dot 3) of total peripheral artery disease DALYs. The prevalence of peripheral artery disease was highest in countries with high SDI and lowest in countries with low SDI, whereas DALY and mortality rates showed U-shaped curves, with the highest burden in the high and low SDI quintiles.Interpretation: The total number of people with peripheral artery disease has increased globally from 1990 to 2019. Despite the lower prevalence of peripheral artery disease in males and low-income countries, these groups showed similar DALY rates to females and higher-income countries, highlighting disproportionate burden in these groups. Modifiable risk factors were responsible for around 70% of the global peripheral artery disease burden. Public measures could mitigate the burden of peripheral artery disease by modifying risk factors.
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| 18. |
- Kristan, Matej, et al.
(författare)
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The Sixth Visual Object Tracking VOT2018 Challenge Results
- 2019
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Ingår i: Computer Vision – ECCV 2018 Workshops. - Cham : Springer Publishing Company. - 9783030110086 - 9783030110093 ; , s. 3-53
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge VOT2018 is the sixth annual tracker benchmarking activity organized by the VOT initiative. Results of over eighty trackers are presented; many are state-of-the-art trackers published at major computer vision conferences or in journals in the recent years. The evaluation included the standard VOT and other popular methodologies for short-term tracking analysis and a “real-time” experiment simulating a situation where a tracker processes images as if provided by a continuously running sensor. A long-term tracking subchallenge has been introduced to the set of standard VOT sub-challenges. The new subchallenge focuses on long-term tracking properties, namely coping with target disappearance and reappearance. A new dataset has been compiled and a performance evaluation methodology that focuses on long-term tracking capabilities has been adopted. The VOT toolkit has been updated to support both standard short-term and the new long-term tracking subchallenges. Performance of the tested trackers typically by far exceeds standard baselines. The source code for most of the trackers is publicly available from the VOT page. The dataset, the evaluation kit and the results are publicly available at the challenge website (http://votchallenge.net).
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| 19. |
- Nguyen-Cong, K., et al.
(författare)
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Billion atom molecular dynamics simulations of carbon at extreme conditions and experimental time and length scales
- 2021
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Ingår i: SC '21: Proceedings of the International Conference for High Performance Computing, Networking, Storage and Analysis. - New York, NY, USA : Association for Computing Machinery (ACM).
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Konferensbidrag (refereegranskat)abstract
- Billion atom molecular dynamics (MD) using quantum-Accurate machine-learning Spectral Neighbor Analysis Potential (SNAP) observed long-sought high pressure BC8 phase of carbon at extreme pressure (12 Mbar) and temperature (5,000 K). 24-hour, 4650 node production simulation on OLCF Summit demonstrated an unprecedented scaling and unmatched real-world performance of SNAP MD while sampling 1 nanosecond of physical time. Efficient implementation of SNAP force kernel in LAMMPS using the Kokkos CUDA backend on NVIDIA GPUs combined with excellent strong scaling (better than 97% parallel efficiency) enabled a peak computing rate of 50.0 PFLOPs (24.9% of theoretical peak) for a 20 billion atom MD simulation on the full Summit machine (27,900 GPUs). The peak MD performance of 6.21 Matom-steps/node-s is 22.9 times greater than a previous record for quantum-Accurate MD. Near perfect weak scaling of SNAP MD highlights its excellent potential to advance the frontier of quantum-Accurate MD to trillion atom simulations on upcoming exascale platforms.
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| 20. |
- Nguyen-Cong, Kien, et al.
(författare)
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Extreme Metastability of Diamond and its Transformation to the BC8 Post-Diamond Phase of Carbon
- 2024
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Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 15:4, s. 1152-1160
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Tidskriftsartikel (refereegranskat)abstract
- Diamond possesses exceptional physical properties due to its remarkably strong carbon-carbon bonding, leading to significant resilience to structural transformations at very high pressures and temperatures. Despite several experimental attempts, synthesis and recovery of the theoretically predicted post-diamond BC8 phase remains elusive. Through quantum-accurate multimillion atom molecular dynamics (MD) simulations, we have uncovered the extreme metastability of diamond at very high pressures, significantly exceeding its range of thermodynamic stability. We predict the post-diamond BC8 phase to be experimentally accessible only within a narrow high pressure-temperature region of the carbon phase diagram. The diamond to BC8 transformation proceeds through premelting followed by BC8 nucleation and growth in the metastable carbon liquid. We propose a double-shock compression pathway for BC8 synthesis, which is currently being explored in experiments at the National Ignition Facility.
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| 21. |
- Piao, Shilong, et al.
(författare)
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Evaluation of terrestrial carbon cycle models for their response to climate variability and to CO2 trends
- 2013
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013. ; 19:7, s. 2117-2132
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to evaluate 10 process-based terrestrial biosphere models that were used for the IPCC fifth Assessment Report. The simulated gross primary productivity (GPP) is compared with flux-tower-based estimates by Jung etal. [Journal of Geophysical Research 116 (2011) G00J07] (JU11). The net primary productivity (NPP) apparent sensitivity to climate variability and atmospheric CO2 trends is diagnosed from each model output, using statistical functions. The temperature sensitivity is compared against ecosystem field warming experiments results. The CO2 sensitivity of NPP is compared to the results from four Free-Air CO2 Enrichment (FACE) experiments. The simulated global net biome productivity (NBP) is compared with the residual land sink (RLS) of the global carbon budget from Friedlingstein etal. [Nature Geoscience 3 (2010) 811] (FR10). We found that models produce a higher GPP (133 +/- 15Pg Cyr-1) than JU11 (118 +/- 6Pg Cyr-1). In response to rising atmospheric CO2 concentration, modeled NPP increases on average by 16% (5-20%) per 100ppm, a slightly larger apparent sensitivity of NPP to CO2 than that measured at the FACE experiment locations (13% per 100ppm). Global NBP differs markedly among individual models, although the mean value of 2.0 +/- 0.8Pg Cyr-1 is remarkably close to the mean value of RLS (2.1 +/- 1.2 Pg Cyr-1). The interannual variability in modeled NBP is significantly correlated with that of RLS for the period 1980-2009. Both model-to-model and interannual variation in model GPP is larger than that in model NBP due to the strong coupling causing a positive correlation between ecosystem respiration and GPP in the model. The average linear regression slope of global NBP vs. temperature across the 10 models is -3.0 +/- 1.5Pg Cyr-1 degrees C-1, within the uncertainty of what derived from RLS (-3.9 +/- 1.1Pg Cyr-1 degrees C-1). However, 9 of 10 models overestimate the regression slope of NBP vs. precipitation, compared with the slope of the observed RLS vs. precipitation. With most models lacking processes that control GPP and NBP in addition to CO2 and climate, the agreement between modeled and observation-based GPP and NBP can be fortuitous. Carbon-nitrogen interactions (only separable in one model) significantly influence the simulated response of carbon cycle to temperature and atmospheric CO2 concentration, suggesting that nutrients limitations should be included in the next generation of terrestrial biosphere models.
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| 22. |
- Piao, Shilong, et al.
(författare)
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Evidence for a weakening relationship between interannual temperature variability and northern vegetation activity.
- 2014
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Satellite-derived Normalized Difference Vegetation Index (NDVI), a proxy of vegetation productivity, is known to be correlated with temperature in northern ecosystems. This relationship, however, may change over time following alternations in other environmental factors. Here we show that above 30°N, the strength of the relationship between the interannual variability of growing season NDVI and temperature (partial correlation coefficient RNDVI-GT) declined substantially between 1982 and 2011. This decrease in RNDVI-GT is mainly observed in temperate and arctic ecosystems, and is also partly reproduced by process-based ecosystem model results. In the temperate ecosystem, the decrease in RNDVI-GT coincides with an increase in drought. In the arctic ecosystem, it may be related to a nonlinear response of photosynthesis to temperature, increase of hot extreme days and shrub expansion over grass-dominated tundra. Our results caution the use of results from interannual time scales to constrain the decadal response of plants to ongoing warming.
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| 23. |
- Wang, Y., et al.
(författare)
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Green Synthesis of Lactone-Based Conjugated Polymers for n-Type Organic Electrochemical Transistors
- 2022
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 32:16
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Tidskriftsartikel (refereegranskat)abstract
- As new and better materials are implemented for organic electrochemical transistors (OECTs), it becomes increasingly important to adopt more economic and environmentally friendly synthesis pathways with respect to conventional transition-metal-catalyzed polymerizations. Herein, a series of novel n-type donor–acceptor-conjugated polymers based on glycolated lactone and bis-isatin units are reported. All the polymers are synthesized via green and metal-free aldol polymerization. The strong electron-deficient lactone-building blocks provide low-lying lowest unoccupied molecular orbital (LUMO) and the rigid backbone needed for efficient electron mobility up to 0.07 cm2 V−1 s−1. Instead, polar atoms in the backbone and ethylene glycol side chains contribute to the ionic conductivity. The resulting OECTs exhibit a normalized maximum transconductance gm,norm of 0.8 S cm−1 and a μC* of 6.7 F cm−1 V−1 s−1. Data on the microstructure show that such device performance originates from a unique porous morphology together with a highly disordered amorphous microstructure, leading to efficient ion-to-electron coupling. Overall, the design strategy provides an inexpensive and metal-free polymerization route for high-performing n-type OECTs.
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| 24. |
- Willman, Jonathan T., et al.
(författare)
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Machine learning interatomic potential for simulations of carbon at extreme conditions
- 2022
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Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 106:18
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Tidskriftsartikel (refereegranskat)abstract
- A spectral neighbor analysis (SNAP) machine learning interatomic potential (MLIP) has been developed for simulations of carbon at extreme pressures (up to 5 TPa) and temperatures (up to 20 000 K). This was achieved using a large database of experimentally relevant quantum molecular dynamics (QMD) data, training the SNAP potential using a robust machine learning methodology, and performing extensive validation against QMD and experimental data. The resultant carbon MLIP demonstrates unprecedented accuracy and transferability in predicting the carbon phase diagram, melting curves of crystalline phases, and the shock Hugoniot, all within 3% of QMD. By achieving quantum accuracy and efficient implementation on leadership-class high-performance computing systems, SNAP advances frontiers of classical MD simulations by enabling atomic-scale insights at experimental time and length scales.
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| 25. |
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| 26. |
- Zhang, Huai, et al.
(författare)
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A global survey on the use of the international classification of diseases codes for metabolic dysfunction-associated fatty liver disease.
- 2024
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Ingår i: Hepatology international. - 1936-0541.
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Tidskriftsartikel (refereegranskat)abstract
- With the implementation of the 11th edition of the International Classification of Diseases (ICD-11) and the publication of the metabolic dysfunction-associated fatty liver disease (MAFLD) nomenclature in 2020, it is important to establish consensus for the coding of MAFLD in ICD-11. This will inform subsequent revisions of ICD-11.Using the Qualtrics XM and WJX platforms, questionnaires were sent online to MAFLD-ICD-11 coding collaborators, authors of papers, and relevant association members.A total of 890 international experts in various fields from 61 countries responded to the survey. We also achieved full coverage of provincial-level administrative regions in China. 77.1% of respondents agreed that MAFLD should be represented in ICD-11 by updating NAFLD, with no significant regional differences (77.3% in Asia and 76.6% in non-Asia, p=0.819). Over 80% of respondents agreed or somewhat agreed with the need to assign specific codes for progressive stages of MAFLD (i.e. steatohepatitis) (92.2%), MAFLD combined with comorbidities (84.1%), or MAFLD subtypes (i.e., lean, overweight/obese, and diabetic) (86.1%).This global survey by a collaborative panel of clinical, coding, health management and policy experts, indicates agreement that MAFLD should be coded in ICD-11. The data serves as a foundation for corresponding adjustments in the ICD-11 revision.
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