| 1. |
- Corander, Jukka, et al.
(författare)
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Learning Genetic Population Structures Using Minimization of Stochastic Complexity
- 2010
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Ingår i: Entropy. - : MDPI AG. - 1099-4300. ; 12:5, s. 1102-1124
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Tidskriftsartikel (refereegranskat)abstract
- Considerable research efforts have been devoted to probabilistic modeling of genetic population structures within the past decade. In particular, a wide spectrum of Bayesian models have been proposed for unlinked molecular marker data from diploid organisms. Here we derive a theoretical framework for learning genetic population structure of a haploid organism from bi-allelic markers for which potential patterns of dependence are a priori unknown and to be explicitly incorporated in the model. Our framework is based on the principle of minimizing stochastic complexity of an unsupervised classification under tree augmented factorization of the predictive data distribution. We discuss a fast implementation of the learning framework using deterministic algorithms.
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| 2. |
- Bomström, Henri, et al.
(författare)
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Digital Twins About Humans—Design Objectives From Three Projects
- 2022
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Ingår i: Journal of Computing and Information Science in Engineering. - : The American Society of Mechanical Engineers. - 1530-9827 .- 1944-7078. ; 22:5
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Tidskriftsartikel (refereegranskat)abstract
- Digital twin (DT) emerges as a key concept of the Industry 4.0 paradigm and beyond. However, the current literature lacks focus on humans and human activities as a part of complex system DTs. Acknowledging human aspects in DTs can enhance work performance, well-being, motivation, and personal development of professionals. This study examines emerging requirements for human digital twins (HDTs) in three use cases of industry–academia collaboration on complex systems. The results draw together the overall design problem and four design objectives for HDTs. We propose to combine the machine and human-related aspects of DTs and highlight the need for virtual-to-virtual interoperability between HDTs and machines alike. Furthermore, we outline differences between humans and machines regarding digital twinning by addressing human activities and knowledge-based behavior on systems. Design of HDTs requires understanding of individual professional characteristics, such as skills and information preferences, together with twinning between the physical and digital machine entities and interactions between the human and machine DTs. As the field moves toward including humans as a part of the DT concept, incorporating HDTs in complex systems emerges as an increasingly significant issue.
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| 3. |
- Juhlin, Magnus, 1975-, et al.
(författare)
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The effect of steering feel on the crosswind performance of buses - Part I : Subjective assessment
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The steering feel is considered to be an important part of the on-centre handling characteristics of vehicles. Therefore, the steering feel is of interest when improving the crosswind performance of buses. In the present paper a methodology is proposed that utilizes a moving-base driving simulator to study the influence of steering feel on the subjective judgement of bus drivers regarding crosswind performance. Results achieved when using this method show that there exists a correlation between the steering feel and the subjective evaluation of crosswind performance. When the drivers are driving a bus with low crosswind sensitivity, it is shown that low yaw rate gradients are preferred for both the steering wheel torque and the steering wheel angle. For more crosswind-sensitive vehicles, the demand for higher yaw rate gradients increases. That is probably due to the increased need for corrections and the fact that more prompt driver corrections are facilitated by higher yaw rate gradients. It can therefore be concluded that, in order to help the driver in a crosswind situation, it would be valuable to be able to change the steering feel characteristics of the vehicle.
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| 8. |
- Bittmann, Simon F., et al.
(författare)
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Ultrafast ring-opening and solvent-dependent product relaxation of photochromic spironaphthopyran
- 2019
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : ROYAL SOC CHEMISTRY. - 1463-9076 .- 1463-9084. ; 21:33, s. 18119-18127
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Tidskriftsartikel (refereegranskat)abstract
- The ultrafast dynamics of unsubstituted spironaphthopyran (SNP) were investigated using femtosecond transient UV and visible absorption spectroscopy in three different solvents and by semi-classical nuclear dynamics simulations. The primary ring-opening of the pyran unit was found to occur in 300 fs yielding a non-planar intermediate in the first singlet excited state (S-1). Subsequent planarisation and relaxation to the product ground state proceed through barrier crossing on the S-1 potential energy surface (PES) and take place within 1.1 ps after excitation. Simulations show that more than 90% of the trajectories involving C-O bond elongation lead to the planar, open-ring product, while relaxation back to the S-0 of the closed-ring form is accompanied by C-N elongation. All ensuing spectral dynamics are ascribed to vibrational relaxation and thermalisation of the product with a time constant of 13 ps. The latter shows dependency on characteristics of the solvent with solvent relaxation kinetics playing a role.
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| 9. |
- Goodfellow, Bradley W., 1971-
(författare)
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A granulometry and secondary mineral fingerprint of chemical weathering in periglacial landscapes and its application to blockfield origins
- 2012
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 57, s. 121-135
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Tidskriftsartikel (refereegranskat)abstract
- A review of published literature was undertaken to determine if there was a fingerprint of chemical weathering in regoliths subjected to periglacial conditions during their formation. If present, this fingerprint would be applied to the question of when blockfields in periglacial landscapes were initiated. These blocky diamicts are usually considered to represent remnants of regoliths that were chemically weathered under a warm, Neogene climate and therefore indicate surfaces that have undergone only a few metres to a few 10s of metres of erosion during the Quaternary. Based on a comparison of clay and silt abundances and secondary mineral assemblages from blockfields, other regoliths in periglacial settings, and regoliths from non-periglacial settings, a fingerprint of chemical weathering in periglacial landscapes was identified. A mobile regolith origin under, at least seasonal, periglacial conditions is indicated where clay(%) ≤ 0.5*silt(%) + 8 across a sample batch. This contrasts with a mobile regolith origin under non-periglacial conditions, which is indicated where clay(%) ≥ 0.5*silt(%) − 6 across a sample batch with clay(%) ≥ 0.5*silt(%) + 8 in at least one sample. A range of secondary minerals, which frequently includes interstratified minerals and indicates high local variability in leaching conditions, is also commonly present in regoliths exposed to periglacial conditions during their formation. Clay/silt ratios display a threshold response to temperature, related to the freezing point of water, but there is little response to precipitation or regolith residence time. Lithology controls clay and silt abundances, which increase from felsic, through intermediate, to mafic compositions, but does not control clay/silt ratios. Use of a sedigraph or Coulter Counter to determine regolith granulometry systematically indicates lower clay abundances and intra-site variability than use of a pipette or hydrometer. In contrast to clay/silt ratios, secondary mineral assemblages vary according to regolith residence time, temperature, and/or precipitation. A microsystems model is invoked as a conceptual framework in which to interpret the concurrent formation of the observed secondary mineral ranges. According to the fingerprint of chemical weathering in periglacial landscapes, there is generally no evidence of blockfield origins under warm Neogene climates. Nearly all blockfields appear to be a product of Quaternary physical and chemical weathering. A more dominant role for periglacial processes in further bevelling elevated, low relief, non-glacial surface remnants in otherwise glacially eroded landscapes is therefore indicated.
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| 10. |
- Schwabl, P, et al.
(författare)
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Colonization and genetic diversification processes of Leishmania infantum in the Americas
- 2021
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Ingår i: Communications biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 4:1, s. 139-
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Tidskriftsartikel (refereegranskat)abstract
- Leishmania infantum causes visceral leishmaniasis, a deadly vector-borne disease introduced to the Americas during the colonial era. This non-native trypanosomatid parasite has since established widespread transmission cycles using alternative vectors, and human infection has become a significant concern to public health, especially in Brazil. A multi-kilobase deletion was recently detected in Brazilian L. infantum genomes and is suggested to reduce susceptibility to the anti-leishmanial drug miltefosine. We show that deletion-carrying strains occur in at least 15 Brazilian states and describe diversity patterns suggesting that these derive from common ancestral mutants rather than from recurrent independent mutation events. We also show that the deleted locus and associated enzymatic activity is restored by hybridization with non-deletion type strains. Genetic exchange appears common in areas of secondary contact but also among closely related parasites. We examine demographic and ecological scenarios underlying this complex L. infantum population structure and discuss implications for disease control.
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