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- Bivik, Caroline, et al.
(författare)
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Novel Genes Involved in Controlling Specification of Drosophila FMRFamide Neuropeptide Cells
- 2015
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Ingår i: Genetics. - : Genetics Society of America. - 0016-6731 .- 1943-2631. ; 200:4, s. 1229-1244
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Tidskriftsartikel (refereegranskat)abstract
- The expression of neuropeptides is often extremely restricted in the nervous system, making them powerful markers for addressing cell specification . In the developing Drosophila ventral nerve cord, only six cells, the Ap4 neurons, of some 10,000 neurons, express the neuropeptide FMRFamide (FMRFa). Each Ap4/FMRFa neuron is the last-born cell generated by an identifiable and well-studied progenitor cell, neuroblast 5-6 (NB5-6T). The restricted expression of FMRFa and the wealth of information regarding its gene regulation and Ap4 neuron specification makes FMRFa a valuable readout for addressing many aspects of neural development, i.e., spatial and temporal patterning cues, cell cycle control, cell specification, axon transport, and retrograde signaling. To this end, we have conducted a forward genetic screen utilizing an Ap4-specific FMRFa-eGFP transgenic reporter as our readout. A total of 9781 EMS-mutated chromosomes were screened for perturbations in FMRFa-eGFP expression, and 611 mutants were identified. Seventy-nine of the strongest mutants were mapped down to the affected gene by deficiency mapping or whole-genome sequencing. We isolated novel alleles for previously known FMRFa regulators, confirming the validity of the screen. In addition, we identified novel essential genes, including several with previously undefined functions in neural development. Our identification of genes affecting most major steps required for successful terminal differentiation of Ap4 neurons provides a comprehensive view of the genetic flow controlling the generation of highly unique neuronal cell types in the developing nervous system.
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| 5. |
- Overgaard, Niels Chr
(författare)
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On the taut string interpretation of the one-dimensional rudin–osher–fatemi model
- 2018
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Ingår i: ICPRAM 2018 - Proceedings of the 7th International Conference on Pattern Recognition Applications and Methods. - : SCITEPRESS - Science and Technology Publications. - 9789897582769 ; , s. 233-244
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Konferensbidrag (refereegranskat)abstract
- A new proof of the equivalence of the Taut String Algorithm and the one-dimensional Rudin–Osher–Fatemi model is presented. Based on duality and the projection theorem in Hilbert space, the proof is strictly elementary. Existence and uniqueness of solutions (in the continuous case) to both denoising models follow as by-products. The standard convergence properties of the denoised signal, as the regularizing parameter tends to zero, are recalled and efficient proofs provided. Moreover, a new and fundamental estimate on the denoised signal is derived. It implies, among other things, the strong convergence (in the space of functions of bounded variation) of the denoised signal to the in-signal as the regularization parameter vanishes.
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- Engwall, Olov
(författare)
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Speaker adaptation of a three-dimensional tongue model
- 2004
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Ingår i: INTERSPEECH 2004. ; , s. 465-468
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Konferensbidrag (refereegranskat)abstract
- Magnetic Resonance Images of nine subjects have been collected to determine scaling factors that can adapt a 3D tongue model to new subjects. The aim is to define few and simple measures that will allow for an automatic, but accurate, scaling of the model. The scaling should be automatic in order to be useful in an application for articulation training, in which the model must replicate the user's articulators without involving the user in a complicated speaker adaptation. It should further be accurate enough to allow for correct acoustic-to-articulatory inversion. The evaluation shows that the defined scaling technique is able to estimate a tongue shape that was not included in the training with an accuracy of 1.5 mm in the midsagittal plane and 1.7 mm for the whole 3D tongue, based on four articulatory measures.
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| 7. |
- Mishchenko, Petr A., et al.
(författare)
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Chiral spin liquids with crystalline Z(2) gauge order in a three-dimensional Kitaev model
- 2020
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Ingår i: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 101:4
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Tidskriftsartikel (refereegranskat)abstract
- Chiral spin liquids (CSLs) are time-reversal-symmetry-breaking ground states of frustrated quantum magnets that show no long-range magnetic ordering but instead exhibit topological order and fractional excitations. Their realization in simple and tractable microscopic models has, however, remained an open challenge for almost two decades until it was realized that Kitaev models on lattices with odd-length loops are natural hosts for such states, even in the absence of a time-reversal-symmetry-breaking magnetic field. Here we report on the formation of CSLs in a three-dimensional Kitaev model on a hypernonagon lattice composed of nine-site loops, which differ from their widely studied two-dimensional counterparts; namely, they exhibit a crystalline ordering of the Z(2) gauge fluxes and thereby break some of the underlying lattice symmetries. We study the formation of these unconventional CSLs via extensive quantum Monte Carlo simulations and demonstrate that they are separated from the featureless paramagnet at high temperatures by a single first-order phase transition at which both time-reversal and lattice symmetries are simultaneously broken. Using variational approaches for the ground state, we explore the effect of varying the Kitaev couplings and find at least five distinct CSL phases, all of which possess crystalline ordering of the Z(2) gauge fluxes. For some of these phases, the complementary itinerant Majorana fermions exhibit gapless band structures with topological features such as Weyl nodes or nodal lines in the bulk and Fermi arc or drumhead surface states.
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| 8. |
- Rodríguez, Juanjo
(författare)
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Mercury methylation in boreal aquatic ecosystems under oxic conditions and climate change : a review
- 2023
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Ingår i: Frontiers in Marine Science. - : Frontiers Media S.A.. - 2296-7745. ; 10
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Forskningsöversikt (refereegranskat)abstract
- Methylmercury (MeHg) formation is a concerning environmental issue described in waters and sediments from multiple aquatic ecosystems. The genetic and metabolic bases of mercury (Hg) methylation have been well described in anoxic environments, but a number of factors seem to point towards alternative pathways potentially occurring in pelagic waters under oxic conditions. Boreal aquatic ecosystems are predicted to undergo increasing concentrations of dissolved organic matter (DOM) as a result of higher terrestrial runoff induced by climate change, which may have important implications in the formation of MeHg in the water column. In this review, different Hg methylation mechanisms postulated in the literature are discussed, with particular focus on potential pathways independent of the hgcAB gene pair and occurring under oxic conditions. Potential effects of DOM on Hg methylation and MeHg bioaccumulation are examined in the context of climate in boreal aquatic ecosystems. Furthermore, the implementation of meta-omic technologies and standardized methods into field measurements and incubation experiments is discussed as a valuable tool to determine taxonomic and functional aspects of Hg methylation in oxic waters and under climate change-induced conditions.
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| 9. |
- Zhong, Kai, et al.
(författare)
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Direct measurements and CFD simulations on ice-induced hull pressure of a ship in floe ice fields
- 2023
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Ingår i: Ocean Engineering. - : Elsevier BV. - 0029-8018. ; 272
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Tidskriftsartikel (refereegranskat)abstract
- Floe ice fields are expected to replace level ice to be the most common environment for future polar sea transportation under the long-term trend of global warming. In this study, the authors aim to develop a viable analysis procedure to predict the ice-induced hull pressure characteristics for ships navigating in floe ice fields. A novel ice model test procedure is established, which is characterized by making use of non-refrigerated synthetic model ice and tactile pressure sensors to measure the hull pressure. The numerical tool is based on a state-of-the-art CFD-DEM numerical framework; a novel method to monitor the hull pressure during the interaction between the hull and ice floes during the CFD-DEM simulations. Statistical analysis indicates the probability distributions of the ice pressure from the experiment and the numerical results are comparable. Besides, the impacts of ship speed and ice floe concentration on the hull pressure distribution are also examined. Increasing speed and ice concentration will make the probability distribution of ice pressure shift towards the high-pressure going interval, resulting in an increased mean of ice pressure. It is also found that increased speed leads to a smaller variance, while increased ice concentration results in a larger variance.
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