The N_f^3 g^6 term in the pressure of hot QCD

We determine the first independent part of the g^6 coefficient in the weak coupling expansion of the QCD pressure at high temperatures, the one proportional to the maximal power of the number of quark flavors N_f. In addition to introducing and developing computational methods that can be used in evaluating other parts of the expansion, our calculation provides a result that becomes dominant in the limit of large N_f and a fixed effective coupling g_{eff}^2 = g^2 N_f/2.Comment: 9 pages, 2 figures, revtex, v2: minor modifications and additional reference

Cold Quark Matter

We perform an O(alpha_s^2) perturbative calculation of the equation of state of cold but dense QCD matter with two massless and one massive quark flavor, finding that perturbation theory converges reasonably well for quark chemical potentials above 1 GeV. Using a running coupling constant and strange quark mass, and allowing for further non-perturbative effects, our results point to a narrow range where absolutely stable strange quark matter may exist. Absent stable strange quark matter, our findings suggest that quark matter in compact star cores becomes confined to hadrons only slightly above the density of atomic nuclei. Finally, we show that equations of state including quark matter lead to hybrid star masses up to M~2M_solar, in agreement with current observations. For strange stars, we find maximal masses of M~2.75M_solar and conclude that confirmed observations of compact stars with M>2M_solar would strongly favor the existence of stable strange quark matter.Comment: 51 pages, 11 figures, v2: minor modifications and additional reference

Can signs of eutrophication be found in the mesozooplankton of Seili, Archipelago Sea?

In this study, we evaluate whether it is possible to distinguish the effects of eutrophication from other, i.e. hydrographical, factors affecting zooplankton. We illustrate our arguments with examples from an old set of zooplankton data which includes 9-year records on mesozooplankton and hydrography collected from Seili, off the south coast of Finland. The present study shows that hydrographic changes override or mask, at least in the time period studied, possible eutrophication effects

Dimensional reduction of the Standard Model coupled to a new singlet scalar field

We derive an effective dimensionally reduced theory for the Standard Model augmented by a real singlet scalar. We treat the singlet as a superheavy field and integrate it out, leaving an effective theory involving only the Higgs and SU(2)(L) x U(1)(y) gauge fields, identical to the one studied previously for the Standard Model. This opens up the possibility of efficiently computing the order and strength of the electroweak phase transition, numerically and nonperturbatively, in this extension of the Standard Model. Understanding the phase diagram is crucial for models of electroweak baryogenesis and for studying the production of gravitational waves at thermal phase transitions.Peer reviewe

Longitudinal perspective on cryptocurrency trading and increased gambling problems : a 3 wave national survey study

Objectives: Cryptocurrency trading has gained popularity over the last few years. Trading is facilitated by online platforms that enable 24/7 trading. Cryptocurrency trading is potentially attractive to gamblers, and it may increase their gambling problems. Furthermore, cryptocurrency trading might be a particularly harmful activity for those gambling offshore. We investigated whether cryptocurrency trading predicts excessive gambling over time. We also analyzed how cryptocurrency trading combined with offshore gambling is associated with excessive gambling. Study design: This was a population-based longitudinal survey study. Methods: We surveyed a sample of Finnish people aged 18–75 years (N = 1022, 51.27% male) at three time points in 6-month intervals: April 2021 (T1), October to November 2021 (T2), and April to May 2022 (T3). Of the original T1 respondents, 66.80% took part in T2 and T3. Outcome measure was excessive gambling using the Problem Gambling Severity Index, and the predictor was cryptocurrency trading. We adjusted models for onshore and offshore gambling online, excessive gaming (Internet Gaming Disorder Test), excessive internet use (Compulsive Internet Use Scale), excessive alcohol use (Alcohol Use Disorders Identification Test), and sociodemographic background factors. We used multilevel regression models to investigate within-person and between-person effects. Results: Cryptocurrency trading has increased in popularity over time. Within-person changes in cryptocurrency trading predicted increased excessive gambling. Excessive gambling was also generally more common among cryptocurrency traders. The full model that was adjusted for the number of confounding factors showed that cryptocurrency trading had a within-person effect on excessive gambling. Of the confounding factors, offshore online gambling, excessive gaming, and excessive internet use had within-person effects on excessive gambling. Offshore and onshore online gamblers and excessive gamers showed more excessive gambling than others. Those participants who were both cryptocurrency traders and offshore gamblers showed significantly higher rate of excessive gambling than others. Conclusions: Cryptocurrency trading is a risky activity and associated with a higher rate of excessive gambling over time. Such activity is especially risky among offshore online gamblers, who could view cryptocurrency trading as another form of gambling or as a way to make money for gambling. Policymakers and counselors should be aware of the risks of cryptocurrency trading.publishedVersionPeer reviewe

Climate-induced hydrography change favours small-bodied zooplankton in a coastal ecosystem

In the Baltic Sea, the climate change is expected to reduce salinity and increase temperature, and shift mesozooplankton communities towards dominance of small-bodied brackish-water taxa and cause a decline in large-bodied marine taxa. Here, we analyse environmental monitoring data, collected in a coastal area in the northern Baltic Archipelago Sea during May–September, 1967––2013, for trends and relationship between mesozooplankton biomass anomalies, salinity and temperature. During the study period, the surface water temperature increased and salinity decreased. Since the mid-1980s, the community was dominated by small-bodied brackish-water taxa whereas large-bodied calanoid copepods and marine taxa were mostly scarce or absent from the samples. The observed decline of marine taxa was related to the decline in salinity and, to some extent, to the increase of temperature. The brackish-water taxa were, for the most part, positively influenced by the temperature increase, although possibly other direct or indirect factors, not considered in this study, were also influencing the dynamics. This study adds to the knowledge of a possible on-going shift in the food web structure towards smaller-sized species and emphasizes the significance of long-term environmental monitoring in understanding the dynamics in plankton communities</p

Spinning Dragging Strings

We use the AdS/CFT correspondence to compute the drag force experienced by a heavy quark moving through a maximally supersymmetric SU(N) super Yang-Mills plasma at nonzero temperature and R-charge chemical potential and at large 't Hooft coupling. We resolve a discrepancy in the literature between two earlier studies of such quarks. In addition, we consider small fluctuations of the spinning strings dual to these probe quarks and find no evidence of instabilities. We make some comments about suitable D7-brane boundary conditions for the dual strings.Comment: 25 pages, 4 figures; v2 refs added; v3 to appear in JHEP, clarifying comment

Host--parasite models on graphs

The behavior of two interacting populations, ``hosts''and ``parasites'', is investigated on Cayley trees and scale-free networks. In the former case analytical and numerical arguments elucidate a phase diagram, whose most interesting feature is the absence of a tri-critical point as a function of the two independent spreading parameters. For scale-free graphs, the parasite population can be described effectively by Susceptible-Infected-Susceptible-type dynamics in a host background. This is shown both by considering the appropriate dynamical equations and by numerical simulations on Barab\'asi-Albert networks with the major implication that in the termodynamic limit the critical parasite spreading parameter vanishes.Comment: 10 pages, 6 figures, submitted to PRE; analytics redone, new calculations added, references added, appendix remove

Oxygen and carbon isoscapes for the Baltic Sea: Testing their applicability in fish migration studies

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Menelaus' theorem, Clifford configurations and inversive geometry of the Schwarzian KP hierarchy

It is shown that the integrable discrete Schwarzian KP (dSKP) equation which constitutes an algebraic superposition formula associated with, for instance, the Schwarzian KP hierarchy, the classical Darboux transformation and quasi-conformal mappings encapsulates nothing but a fundamental theorem of ancient Greek geometry. Thus, it is demonstrated that the connection with Menelaus' theorem and, more generally, Clifford configurations renders the dSKP equation a natural object of inversive geometry on the plane. The geometric and algebraic integrability of dSKP lattices and their reductions to lattices of Menelaus-Darboux, Schwarzian KdV, Schwarzian Boussinesq and Schramm type is discussed. The dSKP and discrete Schwarzian Boussinesq equations are shown to represent discretizations of families of quasi-conformal mappings.Comment: 26 pages, 9 figure