Browsing by Subject "ORDER"

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  • Zappa, Emilio; Dykeman, Eric C.; Geraets, James A.; Twarock, Reidun (2016)
    In this paper we describe a group theoretical approach to the study of structural transitions of icosahedral quasicrystals and point arrays. We apply the concept of Schur rotations, originally proposed by Kramer, to the case of aperiodic structures with icosahedral symmetry; these rotations induce a rotation of the physical and orthogonal spaces invariant under the icosahedral group, and hence, via the cut-and-project method, a continuous transformation of the corresponding model sets. We prove that this approach allows for a characterisation of such transitions in a purely group theoretical framework, and provide explicit computations and specific examples. Moreover, we prove that this approach can be used in the case of finite point sets with icosahedral symmetry, which have a wide range of applications in carbon chemistry (fullerenes) and biology (viral capsids).
  • Kalakoski, Virpi; Henelius, Andreas; Oikarinen, Emilia; Ukkonen, Antti; Puolamäki, Kai (2019)
    Today's ever-increasing amount of data places new demands on cognitive ergonomics and requires new design ideas to ensure successful human-data interaction. Our aim was to identify the cognitive factors that must be considered when designing systems to improve decision-making based on large amounts of data. We constructed a task that simulates the typical cognitive demands people encounter in data analysis situations. We demonstrate some essential cognitive limitations using a behavioural experiment with 20 participants. The studied task presented the participants with critical and noncritical attributes that contained information on two groups of people. They had to select the response option (group) with the higher level of critical attributes. The results showed that accuracy of judgement decreased as the amount of information increased, and that judgement was affected by irrelevant information. Our results thus demonstrate critical cognitive limitations when people utilise data and suggest a cognitive bias in data-based decision-making. Therefore, when designing for cognition, we should consider the human cognitive limitations that are manifested in a data analysis context. Furthermore, we need general cognitive ergonomic guidelines for design that support the utilisation of data and improve data-based decision-making.
  • Söderlund, Peter; von Schoultz, Åsa; Papageorgiou, Achillefs (2021)
    Many studies show that the order of candidates’ names on the ballot has an effect on voting. Less informed and indifferent voters may simplify the voting process by using the ballot position of candidates as a voting cue. By studying six parliamentary elections in Finland, this study first demonstrates that the relationship between ballot position and preference votes follows a reversed J-shaped curve. Candidates listed early on the ballot win the most preference votes, while candidates listed near the end have an advantage over those listed in the middle. Furthermore, the ballot position effect grows stronger with the complexity of the electoral environment. The ballot position effect increases as the number of candidates on the party list increases, the candidates-to-seats ratio increases and the number of incumbents on the list decreases.
  • Ylinen, Sari; Junttila, Katja; Laasonen, Marja; Iverson, Paul; Ahonen, Lauri Valtteri; Kujala, Teija (2019)
    Dyslexia is characterized by poor reading skills, yet often also difficulties in second-language learning. The differences between native- and second-language speech processing and the establishment of new brain representations for spoken second language in dyslexia are not, however, well understood. We used recordings of the mismatch negativity component of event-related potential to determine possible differences between the activation of long-term memory representations for spoken native- and second-language word forms in Finnish-speaking 9-11-year-old children with or without dyslexia, studying English as their second language in school. In addition, we sought to investigate whether the bottleneck of dyslexic readers' second-language learning lies at the level of word representations or smaller units and whether the amplitude of mismatch negativity is correlated with native-language literacy and related skills. We found that the activation of brain representations for familiar second-language words, but not for second-language speech sounds or native-language words, was weaker in children with dyslexia than in typical readers. Source localization revealed that dyslexia was associated with weak activation of the right temporal cortex, which has been previously linked with word-form learning. Importantly, the amplitude of the mismatch negativity for familiar second-language words correlated with native-language literacy and rapid naming scores, suggesting a close link between second-language processing and these skills.
  • Takala, Tuomo; Brockhaus, Maria; Hujala, Teppo; Tanskanen, Minna; Lehtinen, Ari; Tikkanen, Jukka; Toppinen, Anne (2022)
    In many parts of the world, the success of biodiversity conservation strongly depends on the decisions of private landowners. These decisions are guided by the shared perceptions of the biodiversity problem. In this study, we applied a mixed method critical discourse analysis and examined how alternative discourses of biodiversity guide Finnish forest owners to maintain, or not maintain, biodiversity on their lands. Data collection combined a preliminary interview (n = 24) with a forest owner survey (n = 452). We identified four discourses of biodiversity. The concerned discourse acknowledges the biodiversity problems in forests caused by current forestry. The sceptical discourse denies the existence of all biodiversity problems and defends contemporary forestry against the accusations of environmentalists. The harmonising discourse emphasises the harmony of all forest uses in the spirit of multi-objective forestry. The uninvolved discourse distances itself from the biodiversity issue. Overall, only 21% of the survey respondents worried about biodiversity loss in Finnish forests. The discourses illustrate three different ways in which Finnish forest owners moderate the cognitive dissonance caused by 'unpleasant' information on biodiversity loss by either excluding or rejecting it, or assimilating it into multi-objective harmony. Overcoming these kinds of discursive barriers - the mechanisms that help decision-makers ignore alarming realities - is a major challenge for all those who aim to halt biodiversity loss.
  • Andersen, Jens O.; Brauner, Tomas; Hofmann, Christoph P.; Vuorinen, Aleksi (2014)
  • Fan, Zheyong; Chen, Wei; Vierimaa, Ville; Harju, Ari (2017)
    Graphics processing units have been extensively used to accelerate classical molecular dynamics simulations. However, there is much less progress on the acceleration of force evaluations for many-body potentials compared to pairwise ones. In the conventional force evaluation algorithm for many-body potentials, the force, virial stress, and heat current for a given atom are accumulated within different loops, which could result in write conflict between different threads in a CUDA kernel. In this work, we provide a new force evaluation algorithm, which is based on an explicit pairwise force expression for many-body potentials derived recently (Fan et al., 2015). In our algorithm, the force, virial stress, and heat current for a given atom can be accumulated within a single thread and is free of write conflicts. We discuss the formulations and algorithms and evaluate their performance. A new open-source code, GPUMD, is developed based on the proposed formulations. For the Tersoff many-body potential, the double precision performance of GPUMD using a Tesla K40 card is equivalent to that of the LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) molecular dynamics code running with about 100 CPU cores (Intel Xeon CPU X5670 @ 2.93 GHz). (C) 2017 Elsevier B.V. All rights reserved.
  • Cruschina, Silvio (2019)
    In Romance, Focus Fronting (FF) is generally related to a contrastive or corrective function. In this paper, I show that Spanish may resort to FF to express a special evaluative meaning, namely, a mirative (conventional) implicature of surprise and unexpectedness. Mirative FF is problematic for the traditional analyses of FF because it is not necessarily contrastive and does not guarantee the traditional articulation of the sentence into a new and a given part. The results of a syntactic experiment on the distribution and interpretation of FF in European Spanish show that speakers accept FF not only in the corrective but also in the mirative context. The acceptability of mirative FF thus proves that FF in Spanish is not exclusively limited to contrast or linked to information-structural requirements such as the new-old information distinction. FF may also be used to express a mirative implicature that requires a set of focal alternatives in order to be interpreted correctly.
  • Tedersoo, Leho; Sanchez-Ramirez, Santiago; Koljalg, Urmas; Bahram, Mohammad; Doring, Markus; Schigel, Dmitry; May, Tom; Ryberg, Martin; Abarenkov, Kessy (2018)
    High-throughput sequencing studies generate vast amounts of taxonomic data. Evolutionary ecological hypotheses of the recovered taxa and Species Hypotheses are difficult to test due to problems with alignments and the lack of a phylogenetic backbone. We propose an updated phylum-and class-level fungal classification accounting for monophyly and divergence time so that the main taxonomic ranks are more informative. Based on phylogenies and divergence time estimates, we adopt phylum rank to Aphelidiomycota, Basidiobolomycota, Calcarisporiellomycota, Glomeromycota, Entomophthoromycota, Entorrhizomycota, Kickxellomycota, Monoblepharomycota, Mortierellomycota and Olpidiomycota. We accept nine subkingdoms to accommodate these 18 phyla. We consider the kingdom Nucleariae (phyla Nuclearida and Fonticulida) as a sister group to the Fungi. We also introduce a perl script and a newick-formatted classification backbone for assigning Species Hypotheses into a hierarchical taxonomic framework, using this or any other classification system. We provide an example of testing evolutionary ecological hypotheses based on a global soil fungal data set.
  • Kennedy, Juliette; Magidor, Menachem; Väänänen, Jouko (2021)
    If we replace first-order logic by second-order logic in the original definition of Godel's inner model L, we obtain the inner model of hereditarily ordinal definable (HOD) sets [33]. In this paper, we consider inner models that arise if we replace first-order logic by a logic that has some, but not all, of the strength of second-order logic. Typical examples are the extensions of first-order logic by generalized quantifiers, such as the Magidor-Malitz quantifier [24], the cofinality quantifier [35], or stationary logic [6]. Our first set of results show that both L and HOD manifest some amount of formalism freeness in the sense that they are not very sensitive to the choice of the underlying logic. Our second set of results shows that the cofinality quantifier gives rise to a new robust inner model between L and HOD. We show, among other things, that assuming a proper class of Woodin cardinals the regular cardinals > (sic)(1) of V are weakly compact in the inner model arising from the cofinality quantifier and the theory of that model is (set) forcing absolute and independent of the cofinality in question. We do not know whether this model satisfies the Continuum Hypothesis, assuming large cardinals, but we can show, assuming three Woodin cardinals and a measurable above them, that if the construction is relativized to a real, then on a cone of reals, the Continuum Hypothesis is true in the relativized model.
  • Kuopanportti, Pekko; Ropo, Matti; Holmberg, Daniel; Levamaki, Henrik; Kokko, Kalevi; Granroth, Sari; Kuronen, Antti (2022)
    To enable accurate molecular dynamics simulations of iron-chromium alloys with surfaces, we develop, based on density-functional-theory (DFT) calculations, a new interatomic Fe-Cr potential in the Tersoff formalism. Contrary to previous potential models, which have been designed for bulk Fe-Cr, we extend our potential fitting database to include not only conventional bulk properties but also surface-segregation energies of Cr in bcc Fe. In terms of reproducing our DFT results for the bulk properties, the new potential is found to be superior to the previously developed Tersoff potential and competitive with the concentration-dependent and two-band embedded-atom-method potentials. For Cr segregation toward the (100) surface of an Fe-Cr alloy, only the new potential agrees with our DFT calculations in predicting preferential segregation of Cr to the topmost surface layer, instead of the second layer preferred by the other potentials. We expect this rectification to foster future research, e.g., on the mechanisms of corrosion resistance of stainless steels at the atomic level.
  • Helin, Tapio; Lassas, Matti; Ylinen, Lauri; Zhang, Zhidong (2020)
    Given a connected compact Riemannian manifold (M, g) without boundary, dim M >= 2, we consider a space-time fractional diffusion equation with an interior source that is supported on an open subset Vof the manifold. The time-fractional part of the equation is given by the Caputo derivative of order alpha is an element of(0, 1], and the space fractional part by (-Delta(g))(beta), where beta is an element of(0, 1] and Delta(g) is the Laplace-Beltrami operator on the manifold. The case alpha= beta= 1, which corresponds to the standard heat equation on the manifold, is an important special case. We construct a specific source such that measuring the evolution of the corresponding solution on Vdetermines the manifold up to a Riemannian isometry. (c) 2020 Published by Elsevier Inc.
  • Javanainen, Matti; Martinez-Seara, Hector; Vattulainen, Ilpo (2017)
    Biological membranes generate specific functions through compartmentalized regions such as cholesterol-enriched membrane nanodomains that host selected proteins. Despite the biological significance of nanodomains, details on their structure remain elusive. They cannot be observed via microscopic experimental techniques due to their small size, yet there is also a lack of atomistic simulation models able to describe spontaneous nanodomain formation in sufficiently simple but biologically relevant complex membranes. Here we use atomistic simulations to consider a binary mixture of saturated dipalmitoylphosphatidylcholine and cholesterol - the "minimal standard" for nanodomain formation. The simulations reveal how cholesterol drives the formation of fluid cholesterol-rich nanodomains hosting hexagonally packed cholesterol-poor lipid nanoclusters, both of which show registration between the membrane leaflets. The complex nanodomain substructure forms when cholesterol positions itself in the domain boundary region. Here cholesterol can also readily flip-flop across the membrane. Most importantly, replacing cholesterol with a sterol characterized by a less asymmetric ring region impairs the emergence of nanodomains. The model considered explains a plethora of controversial experimental results and provides an excellent basis for further computational studies on nanodomains. Furthermore, the results highlight the role of cholesterol as a key player in the modulation of nanodomains for membrane protein function.
  • Lappi, Pauli Antero; Ollikainen, Markku Martti Olavi (2019)
    This study analyzes socially optimal environmental policy for a mine with a model that takes into account waste or waste rock production and abatement possibilities of the mine. We develop a model, in which the mine produces an externality related to the waste rocks, such as acid mine drainage. We find that the extraction rate tends to be lower in a mine with higher waste rock production, and that the optimal tax on the waste rock production is strictly increasing in time. We extend the model to incorporate an additional externality in the form of a stock pollutant. We analyze the optimal taxes and show that the typical result that the time path of the tax on the stock pollutant is inverted U-shaped may be lost in a mine model with abatement possibility and fixed operation period.
  • Vasko, Petra; Lau, Cheuk W. (2022)
    A series of neutral LM (L = [HC{(H3C)C(Dipp)N}(2)], Dipp = 2,6-(Pr2C6H3)-Pr-i, M = group 13: B-In, TM: Fe, Co, Ni, Cu) and L'M (L' = [HC{(CvCH(2))(CCH3)(DippN)(2)}], M = group 14: C-Pb) compounds including a main group 13/14 and first-row transition metal complexes were studied computationally by density functional theory (DFT). The optimised complexes were assessed in terms of structural parameters and electronic structures to find trends and characteristics that could be used to predict their reactivity towards ammonia. In addition, the differences in oxidative addition and Werner coordination complex formation depending on the identity of the central element were investigated and the Werner complexes were evaluated by QTAIM and EDA-NOCV approaches. The computational results complement the earlier experimental studies and shed light on the feasibility of isolating novel main group Werner complexes or transition metal oxidative addition products.
  • Hamedani, Ali; Byggmästar, Jesper; Djurabekova, Flyura; Alahyarizadeh, G.; Ghaderi, R.; Minuchehr, A.; Nordlund, Kai (2021)
    Characterization of the primary damage is the starting point in describing and predicting the irradiation-induced damage in materials. So far, primary damage has been described by traditional interatomic potentials in molecular dynamics simulations. Here, we employ a Gaussian approximation machine-learning potential (GAP) to study the primary damage in silicon with close to ab initio precision level. We report detailed analysis of cascade simulations derived from our modified Si GAP, which has already shown its reliability for simulating radiation damage in silicon. Major differences in the picture of primary damage predicted by machine-learning potential compared to classical potentials are atomic mixing, defect state at the heat spike phase, defect clustering, and recrystallization rate. Atomic mixing is higher in the GAP description by a factor of two. GAP shows considerably higher number of coordination defects at the heat spike phase and the number of displaced atoms is noticeably greater in GAP. Surviving defects are dominantly isolated defects and small clusters, rather than large clusters, in GAP's prediction. The pattern by which the cascades are evolving is also different in GAP, having more expanded form compared to the locally compact form with classical potentials. Moreover, recovery of the generated defects at the heat spike phase take places with higher efficiency in GAP. We also provide the attributes of the new defect cluster that we had introduced in our previous study. A cluster of four defects, in which a central vacancy is surrounded by three split interstitials, where the surrounding atoms are all 4-folded bonded. The cluster shows higher occurrence in simulations with the GAP potential. The formation energy of the defect is 5.57 eV and it remains stable up to 700 K, at least for 30 ps. The Arrhenius equation predicts the lifetime of the cluster to be 0.0725 mu s at room temperature.
  • Vohra, Anurag; Makkonen, Ilja; Pourtois, Geoffrey; Slotte, Jonatan; Porret, Clement; Rosseel, Erik; Khanam, Afrina; Tirrito, Matteo; Douhard, Bastien; Loo, Roger; Vandervorst, Wilfried (2020)
    This paper benchmarks various epitaxial growth schemes based on n-type group-IV materials as viable source/drain candidates for Ge nMOS devices. Si:P grown at low temperature on Ge, gives an active carrier concentration as high as 3.5 x 10(20) cm(-3) and a contact resistivity down to 7.5 x 10(-9) However, Si:P growth is highly defective due to large lattice mismatch between Si and Ge. Within the material stacks assessed, one option for Ge nMOS source/drain stressors would be to stack Si:P, deposited at contact level, on top of a selectively grown n-SiyGe1-x-ySnx at source/drain level, in line with the concept of Si passivation of n-Ge surfaces to achieve low contact resistivities as reported in literature (Martens et al. 2011 Appl. Phys. Lett., 98, 013 504). The saturation in active carrier concentration with increasing P (or As)-doping is the major bottleneck in achieving low contact resistivities for as-grown Ge or SiyGe1-x-ySnx. We focus on understanding various dopant deactivation mechanisms in P-doped Ge and Ge1-xSnx alloys. First principles simulation results suggest that P deactivation in Ge and Ge1-xSnx can be explained both by P-clustering and donor-vacancy complexes. Positron annihilation spectroscopy analysis, suggests that dopant deactivation in P-doped Ge and Ge1-xSnx is primarily due to the formation of P-n-V and SnmPn-V clusters. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.
  • Sorochkina, Kristina; Zhivonitko, Vladimir V.; Chernichenko, Konstantin; Telkki, Ville-Veikko; Repo, Timo; Koptyug, Igor V. (2018)
    The ability of frustrated Lewis pairs (FLPs) to activate H-2 is of significant interest for metal-free catalysis. The activation of H-2 is also the key element of parahydrogen-induced polarization (PHIP), one of the nuclear spin hyper polarization techniques. It is demonstrated that o-phenylene-based ansa-aminoboranes (AABs) can produce H-1 nuclear spin hyperpolarization through a reversible interaction with parahydrogen at ambient temperatures. Heteronuclei are useful in NMR and MRI as well because they have a broad chemical shift range and long relaxation times and may act as background-free labels. We report spontaneous formation of N-15 hyperpolarization of the N-H site for a family of AABs. The process is efficient at the high magnetic field of an NMR magnet (7 T), and it provides up to 350-fold N-15 signal enhancements. Different hyperpolarization effects are observed with various AAB structures and in a broad temperature range. Spontaneous hyperpolarization, albeit an order of magnitude weaker than that for N-15, was also observed for B-11 nuclei.
  • Zhang, Linli; Huang, Gang; Liu, Anping; Fan, Ruili (2015)
    We introduce the fractional-order derivatives into an HIV infection model with nonlinear incidence and show that the established model in this paper possesses nonnegative solution, as desired in any population dynamics. We also deal with the stability of the infection-free equilibrium, the immune-absence equilibrium, and the immune-presence equilibrium. Numerical simulations are carried out to illustrate the results.
  • Herlan, Claudine Nicole; Sommer, Katharina; Weis, Patrick; Nieger, Martin; Bräse, Stefan (2021)
    Peptoids, or poly-N-substituted glycines, are characterised by broad structural diversity. Compared to peptides, they are less restricted in rotation and lack backbone-derived H bonding. Nevertheless, certain side chains force the peptoid backbone into distinct conformations. Designable secondary structures like helices or nanosheets arise from this knowledge. Herein, we report the copper-catalysed alkyne-azide cycloaddition (CuAAC) of macrocycles to form innovative tube-like tricyclic peptoids, giving access to host-guest chemistry or storage applications. Different linker systems make the single tubes tuneable in size and enable modifications within the gap. An azobenzene linker, which is reversibly switchable in conformation, was successfully incorporated and allowed for light-triggered changes of the entire tricyclic structure.