Browsing by Subject "LIMITS"

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  • Rutkowski, Tomasz; Maak, Istvsn; Vepsäläinen, Kari; Trigos-Peral, Gema; Stephan, Wojciech; Wojtaszyn, Grzegorz; Czechowski, Wojciech (2019)
    Successful evacuation of a peculiar 'colony' of the wood ant Formica polyctena Forst., for years trapped within an old bunker previously used for storing nuclear weapons (see Czechowski et al. 2016), is reported. Using an experimentally installed boardwalk, the imprisoned ants managed to get through the ventilation pipe to their maternal nest on the top of the bunker. In our previous report, we left open the question of how the 'colony' could survive seemingly without food. Here we show that the 'colony' in the bunker survived and grew thanks to an influx of workers from the source nest above the bunker and mass consumption of corpses of the imprisoned nestmates.
  • Holma, Maija; Lindroos, Marko; Romakkaniemi, Atso; Oinonen, Soile (2019)
  • Oishi, Tomohiro; Kortelainen, Markus; Pastore, Alessandro (2017)
    Sensitivity of two-proton emitting decay to nuclear pairing correlation is discussed within a time-dependent three-body model. We focus on the Be-6 nucleus assuming alpha + p + p configuration, and its decay process is described as a time evolution of the three-body resonance state. For a proton-proton subsystem, a schematic density-dependent contact (SDDC) pairing model is employed. From the time-dependent calculation, we observed the exponential decay rule of a two-proton emission. It is shown that the density dependence does not play a major role in determining the decay width, which can be controlled only by the asymptotic strength of the pairing interaction. This asymptotic pairing sensitivity can be understood in terms of the dynamics of the wave function driven by the three-body Hamiltonian, by monitoring the time-dependent density distribution. With this simple SDDC pairing model, there remains an impossible trinity problem: it cannot simultaneously reproduce the empirical Q value, decay width, and the nucleon-nucleon scattering length. This problem suggests that a further sophistication of the theoretical pairing model is necessary, utilizing the two-proton radioactivity data as the reference quantities.
  • Ruuska, Toni; Heikkurinen, Pasi; Wilen, Kristoffer (2020)
    In this article, we study politics as domination. From our point of view, domination, especially in the Anthropocene, has had two vital components-power and supremacy. In order to dominate, one has to have power over others. In addition, the politics of domination, such as colonial oppression of Latin America, has required reasoning, justification, and legitimation, often connected to superiority (because of religion, society, or civilization) from the oppressor's end. Past and present political ideologies and programs, such as colonialism, imperialism, but also welfare state capitalism, neoliberalism and increasingly popular Green New Deal are examples of what we call "anthropolitics", an anthropocentric approach to politics based on domination, power, and supremacist exploitation. In contrast to the prevailing anthropolitics, this article discusses post-Anthropocene politics, characterized by localization and decentralization, as well as a steep reduction of matter-energy throughput by introducing a theoretical frame called ecological realism.
  • Hertzberg, Mark P.; Schiappacasse, Enrico D.; Yanagida, Tsutomu T. (2020)
    We discuss formation of dark matter (DM) mini-halos around primordial black holes (PBHs) and its implication on DM direct detection experiments, including axion searches. Motivated by LIGO observations, we consider f(DM) similar to 0.01as the fraction of DM in PBHs with masses 10M(circle dot) - 70M(circle dot). In this case, we expect the presence of dressed PBHs after Milky Way halo formation with mini-halo masses peaked around M-halo similar to(50 - 55)M-PBH. We analyze the effect of tidal forces acting on dressed PBHs within the Milky Way galaxy. In the solar neighborhood, the mini-halos are resistant against tidal disruption from the mean-field potential of the galaxy and encounters with stars, but they undergo a small level of disruption caused by disk shocking. The presence of mini-halos around LIGO-motivated PBHs today could reduce by half the local dark matter background. High-resolution simulations are encouraged. If the proposed scenario is realized, chances of direct detection of DM would decrease. (C) 2020 The Authors. Published by Elsevier B.V.
  • Hindmarsh, Mark; Rummukainen, Kari; Weir, David J. (2017)
    We perform the first numerical simulations of necklaces in a non-Abelian gauge theory. Necklaces are composite classical solutions which can be interpreted as monopoles trapped on strings, rather generic structures in a Grand Unified Theory. We generate necklaces from random initial conditions, modeling a phase transition in the early Universe, and study the evolution. For all cases, we find that the necklace system shows scaling behavior similar to that of a network of ordinary cosmic strings. Furthermore, our simulations indicate that comoving distance between the monopoles or semipoles along the string asymptotes to a constant value at late times. This means that, while the monopole-to-string energy density ratio decreases as the inverse of the scale factor, a horizon-size length of string has a large number of monopoles, significantly affecting the dynamics of string loops. We argue that gravitational wave bounds from millisecond pulsar timing on the string tension in the Nambu-Goto scenario are greatly relaxed.
  • Batista, Romina; Olsson, Urban; Andermann, Tobias; Aleixo, Alexandre; Ribas, Camila Cherem; Antonelli, Alexandre (2020)
    To elucidate the relationships and spatial range evolution across the world of the bird genus Turdus (Aves), we produced a large genomic dataset comprising ca 2 million nucleotides for ca 100 samples representing 53 species, including over 2000 loci. We estimated time-calibrated maximum-likelihood and multispecies coalescentphylogenies and carried out biogeographic analyses. Our results indicate that there have been considerably fewer trans-oceanic dispersals within the genus Turdus than previously suggested, such that the Palaearctic clade did not originate in America and the African clade was not involved in the colonization of the Americas. Instead, our findings suggest that dispersal from the Western Palaearctic via the Antilles to the Neotropics might have occurred in a single event, giving rise to the rich Neotropical diversity of Turdus observed today, with no reverse dispersals to thePalaearctic or Africa. Our large multilocus dataset, combined with dense species-level sampling and analysed under probabilistic methods, brings important insights into historical biogeography and systematics, even in a scenario of fast and spatially complex diversification.
  • Westerbom, Mats; Mustonen, Olli; Jaatinen, Kim; Kilpi, Mikael; Norkko, Alf (2019)
    Examining changes in abundance and demographic rates at species distribution margins may provide the first signs of broader species responses to environmental change. Still, the joint impact of space and time have remained relatively unstudied in most marginal regions. In order to examine the influence of climate variability on mussel distribution patterns, we monitored three sublittoral and marginal blue mussel (Mytilus trossulus) populations, spaced along a salinity gradient. Densities and biomasses peaked toward the saltier parts of the study area and showed relatively larger variations toward the low saline edge. Temporally, the areas showed a consistent increase in abundance after a synchronized large-scale recruitment event, which was followed by a decline in population size, occurring much faster toward the very range edge. Salinity, temperature, winter severity, and wave exposure explained most of the spatiotemporal variation in mussel abundances and adults showed positive effects on recruit abundance. We show empirically that the dynamics of edge populations are not driven by large changes in climate variables but that small spatial and temporal changes in key environmental variables have large and non-linear population level effects. Our results also show that fluctuating recruitment is a key factor for population stability affecting the storage potential of marginal populations, which dramatically decrease toward the edge. Our study provides a window into future population patterns and processes that drive marginal mussel populations in an altered sea characterized by rising temperature and declining salinity.
  • Byrnes, Christian T.; Hindmarsh, Mark; Young, Sam; Hawkins, Michael R. S. (2018)
    Making use of definitive new lattice computations of the Standard Model thermodynamics during the quantum chromodynamic (QCD) phase transition, we calculate the enhancement in the mass distribution of primordial black holes (PBHs) due to the softening of the equation of state. We find that the enhancement peaks at approximately 0.7 M-circle dot, with the formation rate increasing by at least two orders of magnitude due to the softening of the equation of state at this time, with a range of approximately 0.3 M-circle dot <M <1.4 M-circle dot at full width half-maximum. PBH formation is increased by a smaller amount for PBHs with masses spanning a large range, 10(-3) M-circle dot <M-PBH <10(3) M-circle dot, which includes the masses of the BHs that LIGO detected. The most significant source of uncertainty in the number of PBHs formed is now due to unknowns in the formation process, rather than from the phase transition. A near scale-invariant density power spectrum tuned to generate a population with mass and merger rate consistent with that detected by LIGO should also produce a much larger energy density of PBHs with solar mass. The existence of BHs below the Chandresekhar mass limit would be a smoking gun for a primordial origin and they could arguably constitute a significant fraction of the cold dark matter density. They also pose a challenge to infiationary model building which seek to produce the LIGO BHs without overproducing lighter PBHs.
  • Garate-Escamilla, Homero; Hampe, Arndt; Vizcaino-Palomar, Natalia; Robson, T. Matthew; Garzon, Marta Benito (2019)
    Aim To better understand and more realistically predict future species distribution ranges, it is critical to account for local adaptation and phenotypic plasticity in populations' responses to climate. This is challenging because local adaptation and phenotypic plasticity are trait-dependent and traits covary along climatic gradients, with differential consequences for fitness. Our aim is to quantify local adaptation and phenotypic plasticity of vertical and radial growth, leaf flushing and survival across the range of Fagus sylvatica and to estimate the contribution of each trait to explaining the species' occurrence. Location Europe. Time period 1995-2014; 2070. Major taxa studied Fagus sylvatica L. Methods We used vertical and radial growth, flushing phenology and mortality of F. sylvatica L. recorded in the BeechCOSTe52 database (>150,000 trees). Firstly, we performed linear mixed-effect models that related trait variation and covariation to local adaptation (related to the planted populations' climatic origin) and phenotypic plasticity (accounting for the climate of the plantation), and we made spatial predictions under current and representative concentration pathway (RCP 8.5) climates. Secondly, we combined spatial trait predictions in a linear model to explain the occurrence of the species. Results The contribution of plasticity to intraspecific trait variation is always higher than that of local adaptation, suggesting that the species is less sensitive to climate change than expected; different traits constrain beech's distribution in different parts of its range: the northernmost edge is mainly delimited by flushing phenology (mostly driven by photoperiod and temperature), the southern edge by mortality (mainly driven by intolerance to drought), and the eastern edge is characterized by decreasing radial growth (mainly shaped by precipitation-related variables in our model); considering trait covariation improved single-trait predictions. Main conclusions Population responses to climate across large geographical gradients are dependent on trait x environment interactions, indicating that each trait responds differently depending on the local environment.
  • GREAT-Network; CardShock Investigators; Kimmoun, Antoine; Duarte, Kevin; Harjola, Veli-Pekka; Tarvasmäki, Tuukka; Lassus, Johan; Jurkko, Raija; Tolppanen, Heli; Nieminen, Markku S.; Järvinen, Kristiina; Nieminen, Tuomo; Pulkki, Kari; Soininen, Leena; Sund, Reijo; Tierala, Ilkka; Tolonen, Jukka; Varpula, Marjut (2022)
    Aims Optimal outcome after cardiogenic shock (CS) depends on a coordinated healing response in which both debris removal and extracellular matrix tissue repair play a crucial role. Excessive inflammation can perpetuate a vicious circle, positioning leucocytes as central protagonists and potential therapeutic targets. High levels of circulating Triggering Receptor Expressed on Myeloid cells-1 (TREM-1), were associated with death in acute myocardial infarction confirming excessive inflammation as determinant of bad outcome. The present study aims to describe the association of soluble TREM-1 with 90-day mortality and with various organ injuries in patients with CS. Methods and results This is a post-hoc study of CardShock, a prospective, multicenter study assessing the clinical presentation and management in patients with CS. At the time of this study, 87 patients had available plasma samples at either baseline, and/or 48 h and/or 96-120 h for soluble TREM-1 (sTREM-1) measurements. Plasma concentration of sTREM-1 was higher in 90-day non-survivors than survivors at baseline [median: 1392 IQR: (724-2128) vs. 621 (525-1233) pg/mL, p = 0.008), 48 h (p = 0.019) and 96-120 h (p = 0.029). The highest tertile of sTREM-1 at baseline (threshold: 1347 pg/mL) was associated with 90-day mortality with an unadjusted HR 3.08 CI 95% (1.48-6.42). sTREM-1 at baseline was not associated to hemodynamic parameters (heart rate, blood pressure, use of vasopressors or inotropes) but rather with organ injury markers: renal (estimated glomerular filtration rate, p = 0.0002), endothelial (bio-adrenomedullin, p = 0.018), myocardial (Suppression of Tumourigenicity 2, p = 0.002) or hepatic (bilirubin, p = 0.008). Conclusion In CS patients TREM-1 pathway is highly activated and gives an early prediction of vital organ injuries and outcome. [GRAPHICS] .
  • Nousiainen, J.; Rajani, Chang; Kasper, Markus; Helin, T.; Haffert, S. Y.; Verinaud, C.; Males, J. R.; Van Gorkom, K.; Close, L. M.; Long, J. D.; Hedglen, A. D.; Guyon, O.; Schatz, Lili; Kautz, Markus; Lumbres, J.; Rodack, A.; Knight, J. M.; Miller, Richard K. (2022)
    Context. The direct imaging of potentially habitable exoplanets is one prime science case for the next generation of high contrast imaging instruments on ground-based, extremely large telescopes. To reach this demanding science goal, the instruments are equipped with eXtreme Adaptive Optics (XAO) systems which will control thousands of actuators at a framerate of kilohertz to several kilohertz. Most of the habitable exoplanets are located at small angular separations from their host stars, where the current control laws of XAO systems leave strong residuals. Aims. Current AO control strategies such as static matrix-based wavefront reconstruction and integrator control suffer from a temporal delay error and are sensitive to mis-registration, that is, to dynamic variations of the control system geometry. We aim to produce control methods that cope with these limitations, provide a significantly improved AO correction, and, therefore, reduce the residual flux in the coronagraphic point spread function (PSF). Methods. We extend previous work in reinforcement learning for AO. The improved method, called the Policy Optimization for Adaptive Optics (PO4AO), learns a dynamics model and optimizes a control neural network, called a policy. We introduce the method and study it through numerical simulations of XAO with Pyramid wavefront sensor (PWFS) for the 8-m and 40-m telescope aperture cases. We further implemented PO4AO and carried out experiments in a laboratory environment using Magellan Adaptive Optics eXtreme system (MagAO-X) at the Steward laboratory. Results. PO4AO provides the desired performance by improving the coronagraphic contrast in numerical simulations by factors of 3-5 within the control region of deformable mirror and PWFS, both in simulation and in the laboratory. The presented method is also quick to train, that is, on timescales of typically 5-10 s, and the inference time is sufficiently small (