Articles from TUHAT CRIS


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This collection contains Open Access articles deposited from the University of Helsinki TUHAT CRIS

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  • Cowley, Benjamin Ultan; Charles, Darryl (Cornell University, 2016)
    We present the second in a series of three academic essays which deal with the question of how to build a generalized player model. We begin with a proposition: a general model of players requires parameters for the subjective experience of play, including at least three areas: a) player psychology, b) game structure, and c) actions of play. Based on this proposition, we pose three linked research questions, which make incomplete progress toward a generalized player model: RQ1 what is a necessary and sufficient foundation to a general player model?; RQ2 can such a foundation improve performance of a computational intelligence-based player model?; and RQ3 can such a player model improve efficacy of adaptive artificial intelligence in games? We set out the arguments for each research question in each of the three essays, presented as three preprints. The second essay, in this preprint, illustrates how our 'Behavlets' method can improve the performance and accuracy of a predictive player model in the well-known Pac-Man game, by providing a simple foundation for areas a) to c) above. We then propose a plan for future work to address RQ2 by conclusively testing the Behavlets approach. This plan builds on the work proposed in the first preprint essay to address RQ1, and in turn provides support for work on RQ3. The Behavlets approach was described previously; therefore if citing this work please use the correct citation: Cowley B, Charles D. Behavlets: a Method for Practical Player Modelling using Psychology-Based Player Traits and Domain Specific Features. User Modelling and User-Adapted Interaction. 2016 Feb 8; online (Special Issue on Personality in Personalized Systems):150.
  • Pirralha, André; Dobewall, Henrik (2016)
    This study aims to determine whether subjective well-being has a different psychological meaning for parents and childless respondents. We analyzed comparative data of the third round of the European Social Survey (ESS; N=10,913). After case-control matching, in line with previous work, we found that in some Eastern European countries and Ireland non-mothers report higher SWB levels than mothers. Mothers from the other countries and fathers reported higher SWB levels than non-mothers from these countries and non-fathers. However, resorting to structural equation modelling, we tested for measurement invariance across groups and no indication of differences between parents and childless respondents was found. Having established full scalar measurement invariance, it was determined that measurement is not responsible for the low SWB levels of mothers in some European countries.
  • Wolff, Lili-Ann (Vapaa sivistystyö, 2016)
    Sustainability is not one alternative anymore; it is the only alternative. A large number of researchers are convinced that humanity’s production and consumption have exceeded the limits of planet Earth and that the present development model is unsustainable from environmental, economic, and social perspectives. In this article I will draw on recent research results from various disciplines to show why this is so. Furthermore, I will discuss the implications of the present unsustainable quandaries on education, especially adult education, and suggest new, innovative ways to encounter the present environmental and social challenges.
  • Pirneskoski, Jussi; Perajoki, Katja; Nuutila, Mika; Kuisma, Markku (BioMed Central, 2016)
    Background: The aim of this study was to examine Helsinki Emergency Medical Services (EMS) and hospital records to determine the incidence and possible complications of out-of-hospital deliveries managed by EMS in Helsinki. Methods: We retrospectively analysed all urgent ambulance dispatches relating to childbirth in Helsinki from January 1, 2010 to December 31, 2014 with further analysis of hospital records for the out-of-hospital deliveries. Patients were divided in to two groups: those who delivered before reaching hospital and those who did not deliver before reaching hospital and differences between groups were analysed. Deliveries with gestational age of at least 22 + 0 weeks were considered as births in statistical analysis as this is the current national practice. Results: There were 799 urgent dispatches during the study period. In 102 (12.8 %) of these delivery took place before reaching the hospital. The incidence of EMS managed out-of-hospital delivery was found to be 3.0/1000 births. The annual number of out-of-hospital deliveries attended by EMS increased from 15 in 2010 to 28 in 2014. No stillbirths were reported. Neither maternal or perinatal deaths nor major maternal complications were noted in the study population. Discussion: Out-of-hospital deliveries represent a small minority of EMS calls and remain a challenge to maintaining professional capabilities. Small sample size might have limited the ability of the study to pick up rare complications. Conclusions: The amount of out-of-hospital deliveries in Helsinki increased during the five-year study period. There were no maternal or perinatal mortality or major complications resulting in long-term sequelae associated with the EMS-managed out-of-hospital births.
  • Dhaka, V. D. S; Tkachenko, N. V; Pavelescu, E.-M; Lemmetyinen, H; Hakkarainen, T; Guina, M; Konttinen, J; Okhotnikov, O; Pessa, M; Arstila, Kai; Keinonen, Juhani (Institute of Physics Publishing, 2005)
    Room-temperature carrier dynamics as functions of heavy-ion implantation and subsequent thermal annealing were investigated for technologically important InGaAs/GaAs quantum wells (QWs) by means of a time-resolved up-conversion method. Sub-picosecond lifetimes were achieved at 10 MeV Ni+ doses of (20-50) x 1010 ions cm-2. The decay rates reached a maximum at the highest irradiation dose, yielding the shortest lifetime of the confined QW states of 600 fs. A simple theoretical model is proposed for the photodynamics of the carriers. The relaxation rate depended on the irradiation dose according to a power law of 1.2, while the irradiated and subsequently annealed samples exhibited a power law of 0.35. The results are qualitatively interpreted.
  • Meyer, Steffen; Woodward, Martin; Hertel, Christina; Vlaicu, Philip; Haque, Yasmin; Karner, Jaanika; Macagno, Annalisa; Onuoha, Shimobi C.; Fishman, Dmytro; Peterson, Hedi; Metskula, Kaja; Uibo, Raivo; Jäntti, Kirsi; Hokynar, Kati; Wolff, Anette S. B.; Krohn, Kai; Ranki, Annamari; Peterson, Part; Kisand, Kai; Hayday, Adrian; APECED Patient Collaborative (Cell Press, 2016)
    APS1/APECED patients are defined by defects in the autoimmune regulator (AIRE) that mediates central T cell tolerance to many self-antigens. AIRE deficiency also affects B cell tolerance, but this is incompletely understood. Here we show that most APS1/APECED patients displayed B cell autoreactivity toward unique sets of approximately 100 self-proteins. Thereby, autoantibodies from 81 patients collectively detected many thousands of human proteins. The loss of B cell tolerance seemingly occurred during antibody affinity maturation, an obligatorily T cell-dependent step. Consistent with this, many APS1/APECED patients harbored extremely high-affinity, neutralizing autoantibodies, particularly against specific cytokines. Such antibodies were biologically active in vitro and in vivo, and those neutralizing type I interferons (IFNs) showed a striking inverse correlation with type I diabetes, not shown by other anti-cytokine antibodies. Thus, naturally occurring human autoantibodies may actively limit disease and be of therapeutic utility.
  • Koponen, T; Kinnunen, J; Martikainen, Jani-Petri; Jensen, L. M; Törmä, P (Institute of Physics Publishing, 2006)
    We consider pairing in a two- component atomic Fermi gas, in a three- dimensional optical lattice, when the components have unequal densities, i. e. the gas is polarized. We show that a superfluid where the translational symmetry is broken by a finite Cooper pair momentum, namely a Fulde Ferrel - Larkin - Ovchinnikov ( FFLO)- type state, minimizes the Helmholtz free energy of the system. We demonstrate that such a state is clearly visible in the observable momentum distribution of the atoms, and analyse the dependence of the order parameter and the momentum distribution on the filling fraction and the interaction strength.
  • Kotakoski, J; Nordlund, Kai (Institute of Physics Publishing, 2006)
    "Using carbon nanotubes (CNTs) as building blocks in silicon-based electronics requires good electric contacts between the tubes and other devices. Recent experimental and theoretical works have shown that irradiation can be used to modify both the structure and the electrical properties of nanotubes, and also to create new covalent bonds to different nanotube structures. In this study, we have used atomistic computer simulations with analytical, empirically fitted interaction models, to examine the possibility to enhance binding between a CNT and a silicon substrate with C, Si and Ne ion irradiation. Low irradiation doses (< 2.8 x 10(14) ions/cm(2)) and energies (0.2 - 2.0 keV) were used, to ensure that the irradiated nanotube will not be destroyed. Our results indicate, that ion irradiation can be used to create new covalent bonds, and also to increase the binding energy between these structures, when the irradiation doses and energies are carefully chosen. We found that a typical number of created new covalent C - Si bonds is 0.5 - 0.9 (10(14) ions/cm(2))(-1), and a typical increase in the binding energy between the structures is 100 - 400% for moderate irradiation doses."
  • Brandenburg, A; Käpylä, Petri (Institute of Physics Publishing, 2007)
    Magnetic helicity effects are discussed in laboratory and astrophysical settings. Firstly, dynamo action in Taylor-Green flows is discussed for different boundary conditions. However, because of the lack of scale separation with respect to the container, no large-scale field is being produced and there is no resistively slow saturation phase as otherwise expected. Secondly, the build-up of a large-scale field is demonstrated in a simulation where a localized magnetic eddy produces field on a larger scale if the eddy possesses a swirl. Such a set-up might be realizable experimentally through coils. Finally, new emerging issues regarding the connection between magnetic helicity and the solar dynamo are discussed. It is demonstrated that dynamos with a nonlocal ( Babcock-Leighton type) a effect can also be catastrophically quenched, unless there are magnetic helicity fluxes.
  • Buchs, Gilles; Krasheninnikov, Arkady; Ruffieux, Pascal; Gröning, Pierangelo; Foster, Adam S; Nieminen, Risto M; Gröning, Oliver (Institute of Physics Publishing, 2007)
  • Sipilä, M.; Lushnikov, A. A.; Khriachtchev, L.; Kulmala, M.; Tervahattu, H.; Räsänen, M. (Institute of Physics Publishing, 2007)
  • Buchs, Gilles; Krasheninnikov, Arkady V.; Ruffieux, Pascal; Groening, Pierangelo; Foster, Adam S.; Nieminen, Risto M.; Groening, Oliver (Institute of Physics Publishing, 2007)
  • Gan, Yanjie; Kotakoski, Jani; Krasheninnikov, Arkady V.; Nordlund, Kai; Banhart, F (Institute of Physics Publishing, 2008)
    We combine electron irradiation experiments in a transmission electron microscope with kinetic Monte Carlo simulations to determine the mobility of interstitial carbon atoms in single-walled carbon nanotubes. We measure the irradiation dose necessary to cut nanotubes repeatedly with a focused electron beam as a function of the separation between the cuts and at different temperatures. As the cutting speed is related to the migration of displaced carbon atoms trapped inside the tube and to their recombination with vacancies, we obtain information about the mobility of the trapped atoms and estimate their migration barrier to be about 0.25 eV. This is an experimental confirmation of the remarkably high mobility of interstitial atoms inside carbon nanotubes, which shows that nanotubes have potential applications as pipelines for the transport of carbon atoms.
  • Greenleaf, Allan; Kurylev, Yaroslav; Lassas, Matti; Uhlmann, Gunther (Institute of Physics Publishing, 2008)
  • Koponen, T. K; Paananen, Tomi; Martikainen, Jani-Petri; Bakhtiari, M. R; Törmä, T (Institute of Physics Publishing, 2008)
    We study the phase diagram of an imbalanced two-component Fermi gas in optical lattices of 1-3 dimensions (1D-3D), considering the possibilities of the Fulde-Ferrel-Larkin-Ovchinnikov (FFLO), Sarma/breached pair, BCS and normal states as well as phase separation, at finite and zero temperatures. In particular, phase diagrams with respect to average chemical potential and the chemical potential difference of the two components are considered, because this gives the essential information about the shell structures of phases that will occur in the presence of an additional (harmonic) confinement. These phase diagrams in 1D, 2D and 3D show in a striking way the effect of Van Hove singularities on the FFLO state. Although we focus on population imbalanced gases, the results are relevant also for the (effective) mass imbalanced case. We demonstrate by LDA calculations that various shell structures such as normal-FFLO-BCS-FFLO-normal, or FFLO-normal, are possible in presence of a background harmonic trap. The phases are reflected in noise correlations: especially in 1D the unpaired atoms leave a clear signature of the FFLO state as a zero-correlation area ('breach') within the Fermi sea. This strong signature occurs both for a 1D lattice as well as for a 1D continuum. We also discuss the effect of Hartree energies and the Gorkov correction on the phase diagrams.