| 1. |
- Hultman, Axel
(author)
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Fixed points of zircon automorphisms
- 2008
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In: Order. - : Springer Science and Business Media LLC. - 0167-8094 .- 1572-9273. ; 25:2, s. 85-90
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Journal article (peer-reviewed)abstract
- A zircon is a poset in which every principal order ideal is finite and equipped with a so-called special matching. We prove that the subposet induced by the fixed points of any automorphism of a zircon is itself a zircon. This provides a natural context in which to view recent results on Bruhat orders on twisted involutions in Coxeter groups.
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| 2. |
- Jonsson, Markus, et al.
(author)
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Limit shapes of stable configurations of a generalized Bulgarian solitaire
- 2024
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In: Order. - : Springer Netherlands. - 0167-8094 .- 1572-9273.
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Journal article (other academic/artistic)abstract
- Bulgarian solitaire is played on n cards divided into several piles; a move consists of picking one card from each pile to form a new pile. In a recent generalization, -Bulgarian solitaire, the number of cards you pick from a pile is some function of the pile size, such that you pick cards from a pile of size h. Here we consider a special class of such functions. Let us call well-behaved if and if both and are non-decreasing functions of h. Well-behaved -Bulgarian solitaire has a geometric interpretation in terms of layers at certain levels being picked in each move. It also satisfies that if a stable configuration of n cards exists it is unique. Moreover, if piles are sorted in order of decreasing size () then a configuration is convex if and only if it is a stable configuration of some well-behaved -Bulgarian solitaire. If sorted configurations are represented by Young diagrams and scaled down to have unit height and unit area, the stable configurations corresponding to an infinite sequence of well-behaved functions () may tend to a limit shape . We show that every convex with certain properties can arise as the limit shape of some sequence of well-behaved . For the special case when for , these limit shapes are triangular (in case ), or exponential (in case ), or interpolating between these shapes (in case ).
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| 3. |
- Jonsson, Markus, et al.
(author)
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Markov chains on graded posets : Compatibility of up-directed and down-directed transition probabilities
- 2018
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In: Order. - : Springer Netherlands. - 0167-8094 .- 1572-9273. ; :1, s. 93-109
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Journal article (peer-reviewed)abstract
- We consider two types of discrete-time Markov chains where thestate space is a graded poset and the transitionsare taken along the covering relations in the poset. The first type of Markov chain goes only in one direction, either up or down in the poset (an up chain or down chain). The second type toggles between two adjacent rank levels (an up-and-down chain). We introduce two compatibility concepts between the up-directed transition probabilities (an up rule) and the down-directed(a down rule), and we relate these to compatibility betweenup-and-down chains. This framework is used to prove a conjecture about a limit shape for a process on Young's lattice. Finally, we settle the questions whether the reverse of an up chain is a down chain for some down rule and whether there exists an up or down chain at all if the rank function is not bounded.
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| 4. |
- Ludvigsson, Jonas F., et al.
(author)
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Coeliac disease and risk of sarcoidosis
- 2007
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In: Sarcoidosis Vasculitis and Diffuse Lung Diseases. - Cormano : Casa Editrice Mattioli. - 1124-0490. ; 24:2, s. 121-126
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Journal article (peer-reviewed)abstract
- BACKGROUND AND AIM: Several case reports indicate a link between coeliac disease (CD) and sarcoidosis. Our main objective was to investigate the risk of subsequent sarcoidosis in individuals with CD in a general population cohort study. A second aim was to estimate the risk of CD in individuals with prior sarcoidosis.METHODS: We used Cox proportional hazards method to calculate the risk of subsequent sarcoidosis in 14,349 individuals who had received a diagnosis of CD (1964-2003) and 69,998 age- and sex-matched individuals without a diagnosis of CD. Subjects were identified through the Swedish national Inpatient Register. Conditional logistic regression was used to study the risk of CD associated with prior sarcoidosis.RESULTS: CD was associated with an increased risk of sarcoidosis (Hazard ratio (HR) = 4.03; 95% CI = 2.32-7.00; p < 0.001), and was not notably affected by adjustment for socioeconomic index. In individuals with CD listed as the main diagnosis, the HR was 3.66 (95% CI HR = 1.80-7.45; p < 0.001). Prior sarcoidosis was associated with an increased risk of CD (Odds ratio = 3.58; 95% CI = 1.98-6.45; p < 0.001).CONCLUSION: Immune characteristics of CD may be linked to an increased risk of sarcoidosis.
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| 5. |
- Berthomier, M., et al.
(author)
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Alfven : magnetosphere-ionosphere connection explorers
- 2012
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In: Experimental astronomy. - Dordrecht : Springer. - 0922-6435 .- 1572-9508. ; 33:2-3, s. 445-489
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Journal article (peer-reviewed)abstract
- The aurorae are dynamic, luminous displays that grace the night skies of Earth's high latitude regions. The solar wind emanating from the Sun is their ultimate energy source, but the chain of plasma physical processes leading to auroral displays is complex. The special conditions at the interface between the solar wind-driven magnetosphere and the ionospheric environment at the top of Earth's atmosphere play a central role. In this Auroral Acceleration Region (AAR) persistent electric fields directed along the magnetic field accelerate magnetospheric electrons to the high energies needed to excite luminosity when they hit the atmosphere. The "ideal magnetohydrodynamics" description of space plasmas which is useful in much of the magnetosphere cannot be used to understand the AAR. The AAR has been studied by a small number of single spacecraft missions which revealed an environment rich in wave-particle interactions, plasma turbulence, and nonlinear acceleration processes, acting on a variety of spatio-temporal scales. The pioneering 4-spacecraft Cluster magnetospheric research mission is now fortuitously visiting the AAR, but its particle instruments are too slow to allow resolve many of the key plasma physics phenomena. The Alfv,n concept is designed specifically to take the next step in studying the aurora, by making the crucial high-time resolution, multi-scale measurements in the AAR, needed to address the key science questions of auroral plasma physics. The new knowledge that the mission will produce will find application in studies of the Sun, the processes that accelerate the solar wind and that produce aurora on other planets.
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| 6. |
- Fröding, Barbro, et al.
(author)
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Virtuous Choice and Parity
- 2012
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In: Ethical Theory and Moral Practice. - : Springer Science and Business Media LLC. - 1386-2820 .- 1572-8447. ; 15:1, s. 71-82
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Journal article (peer-reviewed)abstract
- This article seeks to contribute to the discussion on the nature of choice in virtue theory. If several different actions are available to the virtuous agent, they are also likely to vary in their degree of virtue, at least in some situations. Yet, it is widely agreed that once an action is recognised as virtuous there is no higher level of virtue. In this paper we discuss how the virtue theorist could accommodate both these seemingly conflicting ideas. We discuss this issue from a modern Aristotelian perspective, as opposed to a purely exegetic one. We propose a way of resolving what seems to be a major clash between two central features of virtue ethics. Our proposal is based on the notion of parity, a concept which recently has received considerable attention in the literature on axiology. Briefly put, two alternatives are on a par (or are 'roughly equal') if they are comparable, although it is not the case that one is better than the other, nor that they are equally good. The advantages of applying the concept of parity to our problem are twofold. Firstly, it sheds new light on the account of choice in virtue theory. Secondly, some of the criticisms that have been mounted against the possibility of parity can be countered by considering the notion of choice from a virtue theory perspective.
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| 7. |
- Grüne-Yanoff, Till
(author)
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Evolutionary Game Theory, Interpersonal Comparisons and Natural Selection: A Dilemma
- 2011
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In: Philosophy and Biology. - : Springer Science and Business Media LLC. - 0169-3867. ; 26:5, s. 637-654
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Journal article (peer-reviewed)abstract
- When social scientists began employing evolutionary game theory (EGT) in their disciplines, the question arose what the appropriate interpretation of the formal EGT framework would be. Social scientists have given different answer, of which I distinguish three basic kinds. I then proceed to uncover the conceptual tension between the formal framework of EGT, its application in the social sciences, and these three interpretations. First, I argue that EGT under the biological interpretation has a limited application in the social sciences, chiefly because strategy replication often cannot be sensibly interpreted as strategy bearer reproduction in this domain. Second, I show that alternative replication mechanisms imply interpersonal comparability of strategy payoffs. Giving a meaningful interpretation to such comparisons is not an easy task for many social situations, and thus limits the applicability of EGT in this domain. Third, I argue that giving a new interpretation both to strategy replication and selection solves the issue of interpersonal comparability, but at the costs of making the new interpretation incompatible with natural selection interpretations of EGT. To the extent that social scientists seek such a natural selection interpretation, they face a dilemma: either face the challenge that interpersonal comparisons pose, or give up on the natural selection interpretation. By identifying these tensions, my analysis pleas for greater awareness of the specific purposes of EGT modelling in the social sciences, and for greater sensitivity to the underlying microstructure on which the evolutionary dynamics and other EGT solution concepts supervene.
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