| 1. |
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| 2. |
- Cosner, Casey C., et al.
(författare)
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Evolution of Concise and Flexible Synthetic Strategies for Trichostatic Acid and the Potent Histone Deacetylase Inhibitor Trichostatin A
- 2013
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Ingår i: European Journal of Organic Chemistry. - : Wiley. - 1434-193X .- 1099-0690. ; :1, s. 162-172
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Tidskriftsartikel (refereegranskat)abstract
- (R)-(+)-Trichostatic acid and (R)-(+)-trichostatin A (TSA) are natural products that have attracted considerable attention in the field of epigenetic therapies. TSA in particular is a naturally occurring hydroxamic acid having potent activity as a histone deacetylase inhibitor (HDACi) and having significant potential for treatment of a myriad of genetically based diseases. Development of TSA and other trichostatic acid derivatives into useful small-molecule therapies has been hindered by the low natural abundance and high cost associated with these compounds. We report herein our collective efforts towards the development of concise and scalable routes for the synthesis of trichostatic acid and TSA in both racemic and enantioenriched forms. Three independent synthetic pathways were developed with varying degrees of efficiency and convergency. In the first synthesis, the key step was a vinylogous Horner-Wadsworth-Emmons condensation. A Marshall propargylation reaction was used as the key step in the second synthesis, and Pd-catalyzed a-alkenylation of a ketone zinc enolate by using various functionalized alkenyl or dienyl halides was developed for the third synthesis. The second pathway proved to be readily amenable to an enantioselective modification, and both the second and third pathways were straightforwardly adapted for the facile preparation of new analogues of trichostatic acid and TSA.
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| 3. |
- Di Francesco, Davide, et al.
(författare)
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Debottlenecking a Pulp Mill by Producing Biofuels from Black Liquor in Three Steps
- 2021
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 14:11, s. 2414-2425
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Tidskriftsartikel (refereegranskat)abstract
- By extracting lignin, pulp production can be increased without heavy investments in a new recovery boiler, the typical bottleneck of a pulp mill. The extraction is performed by using 0.20 and 0.15 weight equivalents of CO2 and H2SO4 respectively. Herein, we describe lignin esterification with fatty acids using benign reagents to generate a lignin ester mixable with gas oils. The esterification is accomplished by activating the fatty acid and lignin with acetic anhydride which can be regenerated from the acetic acid recycled in this reaction. The resulting mass balance ratio is fatty acid/lignin/acetic acid (2 : 1 : 0.1). This lignin ester can be hydroprocessed to generate hydrocarbons in gasoline, aviation, and diesel range. A 300-hour continuous production of fuel was accomplished. By recirculating reagents from both the esterification step and applying a water gas shift reaction on off-gases from the hydroprocessing, a favorable overall mass balance is realized.
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| 4. |
- Dorange, Ismet, et al.
(författare)
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Allenes as carbon nucleophiles in intramolecular attack on (pi-1,3-diene)palladium complexes : Evidence for trans carbopalladation of the 1,3-diene
- 2003
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 9:14, s. 3445-3449
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Tidskriftsartikel (refereegranskat)abstract
- Reaction of allene-substituted cyclohexa- and cyclohepta-1,3-dienes with [PdCl2(PhCN)(2)] gave eta(3)-( 1,2,3)-cyclohexenyl- and eta(3)-(1,2,3)-cycloheptenylpalladium complexes. respectively. in which C-C bond formation between the allene and the 1.3-diene has occurred. Analysis of the (pi-allyl)palladium complexes by NMR spectroscopy. using reporter ligands, shows that the C-C bond formation has occurred by a trans carbopalladation involving nucleophilic attack by the middle carbon atom of the allene on a (pi-diene)palladium(n) complex. The stereochemistry of the (pi-allyl)palladium complexes was confirmed by benzoquinone-induced stereoselective transformations to allylic acetates.
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| 5. |
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| 6. |
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| 7. |
- Franzén, Johan, et al.
(författare)
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Stereoselective palladium-catalyzed carbocyclization of allenic allylic carboxylates
- 2003
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 125:46, s. 14140-14148
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Tidskriftsartikel (refereegranskat)abstract
- Palladium(0)-catalyzed reaction of allene-substituted allylic carboxylates 3-8 employing 2-5 mol % of Pd(dba)(2) in refluxing toluene leads to the carbocyclization and elimination of carboxylic acid to give bicyclo[4.3.0]nonadiene and bicyclo[5.3.0]decadiene derivatives (12-17). The carbon-carbon bond formation is stereospecific, occurring syn with respect to the leaving group. Addition of maleic anhydride as a ligand to the above-mentioned procedures changed the outcome of the reaction, and under these conditions 3-5 afforded cycloisomerized products 21-23. The experimental results are consistent with a mechanism involving oxidative addition of the allylic carboxylate to Pd(0) to give an electron-deficient (pi-allyl)palladium intermediate, followed by nucleophilic attack by the allene on the face of the pi-allyl opposite to that of the palladium atom. Furthermore, it was found that the Pd(dba)(2)-catalyzed cyclization of the trans-cycloheptene derivative (trans-8) can be directed to give either the trans-fused (trans-17) or the cis-fused (cis-17) ring system by altering the solvent. The former reaction proceeds via a nucleophilic trans-allene attack on the (pi-allyl)palladium intermediate, whereas the latter involves a syn-allene insertion into the allyl-Pd bond of the same intermediate. The products from the carbocylization undergo stereoselective Diels-Alder reactions to give stereodefined polycyclic systems in high yields.
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| 8. |
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| 9. |
- Hedenström, Erik, et al.
(författare)
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Stereoisomeric analysis of 6,10,14-Trimethylpentadecan-2-ol and the corresponding ketone in wing extracts from African Bicyclus butterfly species
- 2015
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 1573-1561 .- 0098-0331. ; 41:1, s. 44-51
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Tidskriftsartikel (refereegranskat)abstract
- Gas chromatography (GC) and mass spectrometry (MS) were used to determine the stereoisomeric compositions of 6,10,14-trimethylpentadecan-2-ol and 6,10,14-trimethylpentadecan-2-one in wing extracts from 17 Bicyclus butterfly species from different regions of Africa. All samples were purified using solid phase extraction (SPE). Since some species contained both alcohol and ketone, these were separated and the ketone was reduced to the alcohol before analysis as either (R)-trans-chrysanthemoyl or (S)-2-acetoxypropionyl esters. A novel asymmetric synthesis was developed for a reference mixture of (2R/S,6S,10R)-6,10,14-trimethylpentadecan-2-ol with known composition of the eight stereoisomers. The mixture then was used as the (R)-trans-chrysanthemoyl esters to correlate each of the eight gas chromatographic peaks to a specific stereoisomer of the extracted wing compounds. Seven butterfly species showed (2R,6R,10R)-configuration of the alcohol, four species contained minute amounts of alcohol too small to determine the stereochemistry, nine species showed (6R,10R)-configuration of the ketone, and one species contained minute amounts of ketone too small to determine the stereochemistry. No other stereoisomers of alcohol or ketone could be detected in the extracts, and the quantities of the compounds in the wing extracts varied from 5 to 900 ng per sample for each species.
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| 10. |
- Löfstedt, Joakim, et al.
(författare)
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Carbon-carbon bond formation in regio- and stereoselective palladium-catalyzed cyclization of allene-substituted conjugated dienes
- 2001
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 66:24, s. 8015-8025
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Tidskriftsartikel (refereegranskat)abstract
- Regio- and stereoselective palladium-catalyzed reactions of allene-substituted 1,3-dienes 1 in acetic acid at room temperature lead to cyclization with formation of a carbon-carbon bond between the middle carbon of the allene and the terminal carbon of the 1,3-diene. Two different types of reactions, both that constitute 1,4-carboacetoxylations of the 1,3-diene, have been developed. In one of the reactions, Pd(II) catalyzes the oxidation of 1 to bicyclic compounds 2, and in the other, Pd(0) catalyzes the transformation of 1 to bicyclic compounds 3. The products 2 are useful for further synthetic transformations and undergo Diels-Alder reactions with dienophiles to give polycyclic ring systems.
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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Nieberding, Caroline. M., et al.
(författare)
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The Male Sex pheromone of the Butterfly Bicyclus anynana : Towards an Evolutionary Analysis
- 2008
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 3:7, s. e2751-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Female sex pheromones attracting mating partners over long distances are a major determinant of reproductive isolation and speciation in Lepidoptera. Males can also produce sex pheromones but their study, particularly in butterflies, has received little attention. A detailed comparison of sex pheromones in male butterflies with those of female moths would reveal patterns of conservation versus novelty in the associated behaviours, biosynthetic pathways, compounds, scent-releasing structures and receiving systems. Here we assess whether the African butterfly Bicyclus anynana, for which genetic, genomic, phylogenetic, ecological and ethological tools are available, represents a relevant model to contribute to such comparative studies.Methodology/Principal Findings: Using a multidisciplinary approach, we determined the chemical composition of the male sex pheromone (MSP) in the African butterfly B. anynana, and demonstrated its behavioural activity. First, we identified three compounds forming the presumptive MSP, namely (Z)-9-tetradecenol (Z9-14:OH), hexadecanal (16:Ald) and 6,10,14-trimethylpentadecan-2-ol (6,10,14-trime-15-2-ol), and produced by the male secondary sexual structures, the androconia. Second, we described the male courtship sequence and found that males with artificially reduced amounts of MSP have a reduced mating success in semi-field conditions. Finally, we could restore the mating success of these males by perfuming them with the synthetic MSP.Conclusions/Significance: This study provides one of the first integrative analyses of a MSP in butterflies. The toolkit it has developed will enable the investigation of the type of information about male quality that is conveyed by the MSP in intraspecific communication. Interestingly, the chemical structure of B. anynana MSP is similar to some sex pheromones of female moths making a direct comparison of pheromone biosynthesis between male butterflies and female moths relevant to future research. Such a comparison will in turn contribute to understanding the evolution of sex pheromone production and reception in butterflies.
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| 15. |
- Simkó, Attila, et al.
(författare)
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Changing the Contrast of Magnetic Resonance Imaging Signals using Deep Learning
- 2021
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Ingår i: Proceedings of the Fourth Conference on Medical Imaging with Deep Learning, PMLR. - : Lübeck University; Hamburg University of Technology. ; , s. 713-727
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Konferensbidrag (refereegranskat)abstract
- The contrast settings to select before acquiring magnetic resonance imaging (MRI) signal depend heavily on the subsequent tasks. As each contrast highlights different tissues, automated segmentation tools for example might be optimized for a certain contrast. While for radiotherapy, multiple scans of the same region with different contrasts can achieve a better accuracy for delineating tumours and organs at risk. Unfortunately, the optimal contrast for the subsequent automated methods might not be known during the time of signal acquisition, and performing multiple scans with different contrasts increases the total examination time and registering the sequences introduces extra work and potential errors. Building on the recent achievements of deep learning in medical applications, the presented work describes a novel approach for transferring any contrast to any other. The novel model architecture incorporates the signal equation for spin echo sequences, and hence the model inherently learns the unknown quantitative maps for proton density, ?1 and ?2 relaxation times (??, ?1 and ?2, respectively). This grants the model the ability to retrospectively reconstruct spin echo sequences by changing the contrast settings Echo and Repetition Time (?? and ??, respectively). The model learns to identify the contrast of pelvic MR images, therefore no paired data of the same anatomy from different contrasts is required for training. This means that the experiments are easily reproducible with other contrasts or other patient anatomies. Despite the contrast of the input image, the model achieves accurate results for reconstructing signal with contrasts available for evaluation. For the same anatomy, the quantitative maps are consistent for a range of contrasts of input images. Realized in practice, the proposed method would greatly simplify the modern radiotherapy pipeline. The trained model is made public together with a tool for testing the model on example images.
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| 16. |
- Simkó, Attila, 1995-
(författare)
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Contributions to deep learning for imaging in radiotherapy
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Purpose: The increasing importance of medical imaging in cancer treatment, combined with the growing popularity of deep learning gave relevance to the presented contributions to deep learning solutions with applications in medical imaging.Relevance: The projects aim to improve the efficiency of MRI for automated tasks related to radiotherapy, building on recent advancements in the field of deep learning.Approach: Our implementations are built on recently developed deep learning methodologies, while introducing novel approaches in the main aspects of deep learning, with regards to physics-informed augmentations and network architectures, and implicit loss functions. To make future comparisons easier, we often evaluated our methods on public datasets, and made all solutions publicly available.Results: The results of the collected projects include the development of robust models for MRI bias field correction, artefact removal, contrast transfer and sCT generation. Furthermore, the projects stress the importance of reproducibility in deep learning research and offer guidelines for creating transparent and usable code repositories.Conclusions: Our results collectively build the position of deep learning in the field of medical imaging. The projects offer solutions that are both novel and aim to be highly applicable, while emphasizing generalization towards a wide variety of data and the transparency of the results.
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| 17. |
- Simkó, Attila, et al.
(författare)
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Improving MR image quality with a multi-task model, using convolutional losses
- 2023
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Ingår i: BMC Medical Imaging. - : BioMed Central (BMC). - 1471-2342. ; 23:1
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: During the acquisition of MRI data, patient-, sequence-, or hardware-related factors can introduce artefacts that degrade image quality. Four of the most significant tasks for improving MRI image quality have been bias field correction, super-resolution, motion-, and noise correction. Machine learning has achieved outstanding results in improving MR image quality for these tasks individually, yet multi-task methods are rarely explored.METHODS: In this study, we developed a model to simultaneously correct for all four aforementioned artefacts using multi-task learning. Two different datasets were collected, one consisting of brain scans while the other pelvic scans, which were used to train separate models, implementing their corresponding artefact augmentations. Additionally, we explored a novel loss function that does not only aim to reconstruct the individual pixel values, but also the image gradients, to produce sharper, more realistic results. The difference between the evaluated methods was tested for significance using a Friedman test of equivalence followed by a Nemenyi post-hoc test.RESULTS: Our proposed model generally outperformed other commonly-used correction methods for individual artefacts, consistently achieving equal or superior results in at least one of the evaluation metrics. For images with multiple simultaneous artefacts, we show that the performance of using a combination of models, trained to correct individual artefacts depends heavily on the order that they were applied. This is not an issue for our proposed multi-task model. The model trained using our novel convolutional loss function always outperformed the model trained with a mean squared error loss, when evaluated using Visual Information Fidelity, a quality metric connected to perceptual quality.CONCLUSION: We trained two models for multi-task MRI artefact correction of brain, and pelvic scans. We used a novel loss function that significantly improves the image quality of the outputs over using mean squared error. The approach performs well on real world data, and it provides insight into which artefacts it detects and corrects for. Our proposed model and source code were made publicly available.
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| 18. |
- Simkó, Attila, et al.
(författare)
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MRI bias field correction with an implicitly trained CNN
- 2022
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Ingår i: Proceedings of the 5th international conference on medical imaging with deep learning. - : ML Research Press. ; , s. 1125-1138
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Konferensbidrag (refereegranskat)abstract
- In magnetic resonance imaging (MRI), bias fields are difficult to correct since they are inherently unknown. They cause intra-volume intensity inhomogeneities which limit the performance of subsequent automatic medical imaging tasks, \eg, tissue-based segmentation. Since the ground truth is unavailable, training a supervised machine learning solution requires approximating the bias fields, which limits the resulting method. We introduce implicit training which sidesteps the inherent lack of data and allows the training of machine learning solutions without ground truth. We describe how training a model implicitly for bias field correction allows using non-medical data for training, achieving a highly generalized model. The implicit approach was compared to a more traditional training based on medical data. Both models were compared to an optimized N4ITK method, with evaluations on six datasets. The implicitly trained model improved the homogeneity of all encountered medical data, and it generalized better for a range of anatomies, than the model trained traditionally. The model achieves a significant speed-up over an optimized N4ITK method—by a factor of 100, and after training, it also requires no parameters to tune. For tasks such as bias field correction - where ground truth is generally not available, but the characteristics of the corruption are known - implicit training promises to be a fruitful alternative for highly generalized solutions.
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| 19. |
- Simkó, Attila, et al.
(författare)
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Reproducibility of the methods in medical imaging with deep learning
- 2023
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Ingår i: Medical imaging with deep learning 2023. - : ML Research Press. ; , s. 95-106
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Konferensbidrag (refereegranskat)abstract
- Concerns about the reproducibility of deep learning research are more prominent than ever, with no clear solution in sight. The Medical Imaging with Deep Learning (MIDL) conference has made advancements in employing empirical rigor with regards to reproducibility by advocating open access, and recently also recommending authors to make their code public—both aspects being adopted by the majority of the conference submissions. We have evaluated all accepted full paper submissions to MIDL between 2018 and 2022 using established, but adjusted guidelines addressing the reproducibility and quality of the public repositories. The evaluations show that publishing repositories and using public datasets are becoming more popular, which helps traceability, but the quality of the repositories shows room for improvement in every aspect. Merely 22% of all submissions contain a repository that was deemed repeatable using our evaluations. From the commonly encountered issues during the evaluations, we propose a set of guidelines for machine learning-related research for medical imaging applications, adjusted specifically for future submissions to MIDL. We presented our results to future MIDL authors who were eager to continue an open discussion on the topic of code reproducibility.
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| 20. |
- Simkó, Attila, et al.
(författare)
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Towards MR contrast independent synthetic CT generation
- 2024
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Ingår i: Zeitschrift für Medizinische Physik. - : Elsevier. - 0939-3889 .- 1876-4436. ; 34:2, s. 270-277
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Tidskriftsartikel (refereegranskat)abstract
- The use of synthetic CT (sCT) in the radiotherapy workflow would reduce costs and scan time while removing the uncertainties around working with both MR and CT modalities. The performance of deep learning (DL) solutions for sCT generation is steadily increasing, however most proposed methods were trained and validated on private datasets of a single contrast from a single scanner. Such solutions might not perform equally well on other datasets, limiting their general usability and therefore value. Additionally, functional evaluations of sCTs such as dosimetric comparisons with CT-based dose calculations better show the impact of the methods, but the evaluations are more labor intensive than pixel-wise metrics.To improve the generalization of an sCT model, we propose to incorporate a pre-trained DL model to pre-process the input MR images by generating artificial proton density, T1 and T2 maps (i.e. contrast-independent quantitative maps), which are then used for sCT generation. Using a dataset of only T2w MR images, the robustness towards input MR contrasts of this approach is compared to a model that was trained using the MR images directly. We evaluate the generated sCTs using pixel-wise metrics and calculating mean radiological depths, as an approximation of the mean delivered dose. On T2w images acquired with the same settings as the training dataset, there was no significant difference between the performance of the models. However, when evaluated on T1w images, and a wide range of other contrasts and scanners from both public and private datasets, our approach outperforms the baseline model. Using a dataset of T2w MR images, our proposed model implements synthetic quantitative maps to generate sCT images, improving the generalization towards other contrasts. Our code and trained models are publicly available.
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| 21. |
- Srivastava, Vaibhav, et al.
(författare)
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OnPLS integration of transcriptomic, proteomic and metabolomic data shows multi-level oxidative stress responses in the cambium of transgenic hipI- superoxide dismutase Populus plants
- 2013
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Ingår i: BMC Genomics. - : BioMed Central. - 1471-2164. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Reactive oxygen species (ROS) are involved in the regulation of diverse physiological processes in plants, including various biotic and abiotic stress responses. Thus, oxidative stress tolerance mechanisms in plants are complex, and diverse responses at multiple levels need to be characterized in order to understand them. Here we present system responses to oxidative stress in Populus by integrating data from analyses of the cambial region of wild-type controls and plants expressing high-isoelectric-point superoxide dismutase (hipI-SOD) transcripts in antisense orientation showing a higher production of superoxide. The cambium, a thin cell layer, generates cells that differentiate to form either phloem or xylem and is hypothesized to be a major reason for phenotypic perturbations in the transgenic plants. Data from multiple platforms including transcriptomics (microarray analysis), proteomics (UPLC/QTOF-MS), and metabolomics (GC-TOF/MS, UPLC/MS, and UHPLC-LTQ/MS) were integrated using the most recent development of orthogonal projections to latent structures called OnPLS. OnPLS is a symmetrical multi-block method that does not depend on the order of analysis when more than two blocks are analysed. Significantly affected genes, proteins and metabolites were then visualized in painted pathway diagrams.RESULTS: The main categories that appear to be significantly influenced in the transgenic plants were pathways related to redox regulation, carbon metabolism and protein degradation, e.g. the glycolysis and pentose phosphate pathways (PPP). The results provide system-level information on ROS metabolism and responses to oxidative stress, and indicate that some initial responses to oxidative stress may share common pathways.CONCLUSION: The proposed data evaluation strategy shows an efficient way of compiling complex, multi-platform datasets to obtain significant biological information.
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| 22. |
- Vu, Minh Hoang, 1988-
(författare)
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Resource efficient automatic segmentation of medical images
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cancer is one of the leading causes of death worldwide. In 2020, there were around 10 million cancer deaths and nearly 20 million new cancer cases in the world. Radiation therapy is essential in cancer treatments because half of the cancer patients receive radiation therapy at some point. During a radiotherapy treatment planning (RTP), an oncologist must manually outline two types of areas of the patient’s body: target, which will be treated, and organs-at-risks (OARs), which are essential to avoid. This step is called delineation. The purpose of the delineation is to generate a sufficient dose plan that can provide adequate radiation dose to a tumor and limit the radiation exposure to healthy tissue. Therefore, accurate delineations are essential to achieve this goal.Delineation is tedious and demanding for oncologists because it requires hours of concentrating work doing a repeated job. This is a RTP bottleneck which is often time- and resource-intensive. Current software, such as atlasbased techniques, can assist with this procedure by registering the patient’s anatomy to a predetermined anatomical map. However, the atlas-based methods are often slowed down and erroneous for patients with abnormal anatomies.In recent years, deep learning (DL) methods, particularly convolutional neural networks (CNNs), have led to breakthroughs in numerous medical imaging applications. The core benefits of CNNs are weight sharing and that they can automatically detect important visual features. A typical application of CNNs for medical images is to automatically segment tumors, organs, and structures, which is assumed to save radiation oncologists much time when delineating. This thesis contributes to resource efficient automatic segmentation and covers different aspects of resource efficiency.In Paper I, we proposed a novel end-to-end cascaded network for semantic segmentation in brain tumors in the multi-modal magnetic resonance imaging challenge in 2019. The proposed method used the hierarchical structure of the tumor sub-regions and was one of the top-ranking teams in the task of quantification of uncertainty in segmentation. A follow-up work to this paper was ranked second in the same task in the same challenge a year later.We systematically assessed the segmentation performance and computational costs of the technique called pseudo-3D as a function of the number of input slices in Paper II. We compared the results to typical two-dimensional (2D) and three-dimensional (3D) CNNs and a method called triplanar orthogonal 2D. The typical pseudo-3D approach considers adjacent slices to be several image input channels. We discovered that a substantial benefit from employing multiple input slices was apparent for a specific input size.We introduced a novel loss function in Paper III to address diverse issues, including imbalanced datasets, partially labeled data, and incremental learning. The proposed loss function adjusts to the given data to use all accessible data, even if some lack annotations. We show that the suggested loss function also performs well in an incremental learning context, where an existing model can be modified to incorporate the delineations of newly appearing organs semi-automatically.In Paper IV, we proposed a novel method for compressing high-dimensional activation maps, which are the primary source of memory use in modern systems. We examined three distinct compression methods for the activation maps to accomplishing this. We demonstrated that the proposed method induces a regularization effect that acts on the layer weight gradients. By employing the proposed technique, we reduced activation map memory usage by up to 95%.We investigated the use of generative adversarial networks (GANs) to enlarge a small dataset by generating synthetic images in Paper V. We use the real and generated data during training CNNs for the downstream segmentation tasks. Inspired by an existing GAN, we proposed a conditional version to generate high-dimensional and high-quality medical images of different modalities and their corresponding label maps. We evaluated the quality of the generated medical images and the effect of this augmentation on the performance of the segmentation task on six datasets.
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| 23. |
- Wahlström, Joakim, 1994-, et al.
(författare)
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Psychosocial Working Conditions in School and Life Satisfaction among Adolescents in Sweden: A Cross-Sectional Study
- 2021
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1660-4601 .- 1661-7827. ; 18:10
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Tidskriftsartikel (refereegranskat)abstract
- Poor psychosocial working conditions in school have consistently been shown to be associated with adverse health among adolescents. However, the relationships between school demands, teacher support, and classmate support and positive aspects of health have not been explored to the same extent. The aim of this study was to examine differences in psychosocial working conditions in school and in life satisfaction by gender and by grade, and to investigate the association between psychosocial working conditions in school and life satisfaction among boys and girls, and among students in different grades. Data from the Swedish Health Behavior in School-Aged Children (HBSC) study of 2017/18 were used, consisting of 3614 students in Grades 5, 7, and 9 (similar to 11, 13, and 15 years). Psychosocial working conditions in school were captured by indices of perceived school demands, teacher support, and classmate support. Life satisfaction was measured by the 11-step Cantril's ladder (using cutoffs at >5 and >8, respectively). Whereas girls reported higher school demands than boys, higher levels of teacher and classmate support were reported by boys. Students in lower grades reported lower school demands but higher levels of teacher and classmate support compared with students in higher grades. Boys and students in lower grades were more likely to report high life satisfaction compared with girls and students in higher grades. Results from binary logistic regression analyzes showed that school demands were inversely associated with life satisfaction, and that higher levels of teacher support and classmate support were associated with high life satisfaction. These results were found for both boys and girls, and for students in all grades. The findings indicate that schools have the potential to promote positive health among students.
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| 24. |
- Wahlström, Joakim, 1994-, et al.
(författare)
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Sense of Unity and Self-Reported Health Among 15-year-Olds: Findings From the Swedish 2017/18 Health Behavior in School-Aged Children Study
- 2021
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Ingår i: International Journal of Public Health. - : Frontiers Media SA. - 1661-8556 .- 1661-8564. ; 66
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Sense of unity refers to the positive feeling of being part of a larger social structure. This study aimed to investigate to what extent adolescents report sense of unity and if this differs across groups, and to assess the associations between sense of unity and self-reported health while taking into account sociodemographic characteristics and tangible social relationships. Methods: Data were obtained from the 2017/18 Swedish Health Behavior in School-aged Children study, using information collected among 15-year-old students (n = 1,392). Linear and binary logistic regression analyses were performed. Results: The participants reported overall high levels of sense of unity. Sense of unity did not differ by gender, but adolescents without an immigrant background and those with higher family affluence reported higher levels. Sense of unity was inversely associated with psychological complaints, somatic complaints, and less than good self-rated health, even when adjusting for sociodemographic characteristics and family, classmate, and teacher relationships. Conclusion: This study suggests that sense of unity may be an important social determinant for adolescent health. More research is needed on the origins and implications of sense of unity.
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| 25. |
- Wahlström, Joakim, 1994-, et al.
(författare)
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There's a tear in my beer: Bullying victimisation and young teenage drinking in Sweden
- 2023
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Ingår i: CHILDREN AND YOUTH SERVICES REVIEW. - 0190-7409 .- 1873-7765. ; 154
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Tidskriftsartikel (refereegranskat)abstract
- Victims of bullying are at an increased risk not only of developing adverse mental health, but also of engaging in health risk behaviours. One way in which adolescents may cope with the health-related consequences of bullying victimisation is through substance use such as alcohol and narcotics, as posited by the self-medication hypothesis. Indeed, previous research has found a link between traditional (face-to-face) bullying victimisation and alcohol use among adolescents, albeit with some inconsistencies. However, studies examining both traditional bullying and cyberbullying among youth often report an association only between cyberbullying victimisation and drinking. The current study seeks to add to this field of research by analysing the predictive capacity of traditional and cyberbullying victimisation for youth drinking whilst also adjusting for bullying perpetration and sociodemographic characteristics. In the analyses, we distinguished between occasional and frequent victimisation, and performed separate investigations of how specific types of traditional bullying and cyberbullying victimisation are related to youth drinking.Data were obtained from the Swedish Health Behaviour in School-aged Children (HBSC) survey, with pooled cross-sectional information from 2013/14 and 2017/18 collected among 13- and 15-year-old students (n = 7126). Any alcohol use and drunkenness during the past 30 days were used as dependent variables. The respondents were categorised as non-victims, occasional victims, and frequent victims of traditional and cyberbullying, respectively. Binary logistic regression analyses were performed to examine the associations between bullying victimisation and youth drinking.The results showed that 21.2% of students reported that they had been bullied at least once or twice in the past months, either as victims of traditional bullying only (8.3%), cyberbullying only (7.8%), or both (5.1%). When both types of bullying victimisation were mutually adjusted for, only cyberbullying remained significantly associated with an increased risk of drinking. However, when specific types of face-to-face bullying victimisation were analysed, several statistically significant associations with youth drinking were found, even when controlling for cyberbullying victimisation. Associations with any alcohol use and drunkenness were overall very similar.To conclude, this study corroborates previous research which has shown youth drinking to be more consistently related with cyberbullying victimisation than with traditional bullying victimisation. The study also extends previous knowledge by showing that the association between traditional bullying victimisation and youth drinking differs depending on the operationalisation of victimisation. Future research might benefit from examining this more thoroughly. The findings highlight that interventions targeting bullying and its effects should consider both face-to-face and online victimisation.
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