Introduction of Florida Bass Alleles into Largemouth Bass Inhabiting NortheastArkansas Stream Systems

Florida bass (Micropterus floridanus) have been introduced throughout much of the southern U.S. over the past 50 years. This species readily hybridizes with the extant largemouth bass (M. salmoides). Within Arkansas, the Florida bass is currently stocked in the southern half of the state. Previous studies of a northern Arkansas hatchery and a reservoir revealed the existence of Florida bass alleles in each. Other studies in Oklahoma and Texas have revealed the presence of Florida bass alleles in stream systems proximal to lakes stocked. Our goal was to investigate, using microsatellite analysis of 7 diagnostic loci, the presence of Florida bass alleles in 8 northeastern Arkansas streams to determine if Florida bass or hybrids had escaped from private farm ponds as compared to stocked reservoirs. We found rare instances of Florida bass alleles in most drainages, consistent with previous studies demonstrating a lack of containment of Florida bass once stocked. In Cane Creek, which flows adjacent to privately stocked farm ponds, one-third of the individuals had Florida bass alleles

Constraints on Variant Axion Models

A particular class of variant axion models with two higgs doublets and a singlet is studied. In these models the axion couples either to the $u$-quark or $t$-quark or both, but not to $b$, $c$, $s$, or $d$. When the axion couples to only one quark the models possess the desirable feature of having no domain wall problem, which makes them viable candidates for a cosmological axion string scenario. We calculate the axion couplings to leptons, photons and nucleons, and the astrophysical constraints on the axion decay constant $v_a$ are investigated and compared to the DFSZ axion model. We find that the most restrictive lower bound on $v_a$, that from SN1987a, is lowered by up to a factor of about 30, depending on the model and also the ratio of the vacuum expectation values of the higgs doublets. For scenarios with axionic strings, the allowed window for $v_a$ in the $u$ quark model can be more than two orders of magnitude. For inflationary scenarios, the cosmological upper bound on $v_a/N$, where $N$ is the QCD anomaly factor, is unaffected: however, the variant models have $N$ either 3 or 6 times smaller than the DFSZ model.Comment: 21pp RevTeX, 1 eps fig, uses graphics style, typo corrected, and corrected file sent this time. To appear in Physical Review

Dimming Supernovae without Cosmic Acceleration

We present a simple model where photons propagating in extra-galactic magnetic fields can oscillate into very light axions. The oscillations may convert some of the photons departing a distant supernova into axions, making the supernova appear dimmer and hence more distant than it really is. Averaging over different configurations of the magnetic field we find that the dimming saturates at about 1/3 of the light from the supernovae at very large redshifts. This results in a luminosity-distance vs. redshift curve almost indistinguishable from that produced by the accelerating Universe, if the axion mass and coupling scale are m ~ 10^-16 eV, M ~ 4 10^11 GeV. This phenomenon may be an alternative to the accelerating Universe for explaining supernova observations.Comment: 11 pages, LaTex, 2 figures included. Comments on effects of refraction within galaxies and references adde

A Search for leptophilic Z_(l) boson at future linear colliders

We study the possible dynamics associated with leptonic charge in future linear colliders. Leptophilic massive vector boson, Z_(l), have been investigated through the process e^(+)e^(-) -> mu^(+)mu^(-). We have shown that ILC and CLIC will give opportunity to observe Z_(l) with masses up to the center of mass energy if the corresponding coupling constant g_(l) exceeds 10^(-3).Comment: 12 pages, 10 figure

A complete 3D numerical study of the effects of pseudoscalar-photon mixing on quasar polarizations

We present the results of three-dimensional simulations of quasar polarizations in the presence of pseudoscalar-photon mixing in the intergalactic medium. The intergalactic magnetic field is assumed to be uncorrelated in wave vector space but correlated in real space. Such a field may be obtained if its origin is primordial. Furthermore we assume that the quasars, located at cosmological distances, have negligible initial polarization. In the presence of pseudoscalar-photon mixing we show, through a direct comparison with observations, that this may explain the observed large scale alignments in quasar polarizations within the framework of big bang cosmology. We find that the simulation results give a reasonably good fit to the observed data.Comment: 15 pages, 8 figures, significant changes, to appear in EPJ

Fossil energy in economic growth: A study of the energy direction of technical change, 1950-2012

Climate change mitigation challenges national economies to increase productivity while reducing fossil energy consumption. Fossil energy-saving technical change has been assumed to accomplish this, yet empirical evidence is scarce. This paper investigates the long-run relationship between the rate and direction of technical change with respect to fossil energy and labor in the world economy. Growth rates of labor productivity and the fossil energy-labor ratio are examined for more than 95 of world output between 1950 and 2012. The average elasticity of the energy-labor ratio with respect to labor productivity is close to one, implying highly energy-using technical change, but no trade-o between factor productivity growth rates. This stylized fact suggests the importance of a cheap, abundant energy supply for robust global growth, and a more important role for renewable energy. Integrated assessment models do not incorporate this restriction which may result in poorly speci ed baseline scenarios

Decadal changes in fire frequencies shift tree communities and functional traits

Global change has resulted in chronic shifts in fire regimes. Variability in the sensitivity of tree communities to multi-decadal changes in fire regimes is critical to anticipating shifts in ecosystem structure and function, yet remains poorly understood. Here, we address the overall effects of fire on tree communities and the factors controlling their sensitivity in 29 sites that experienced multi-decadal alterations in fire frequencies in savanna and forest ecosystems across tropical and temperate regions. Fire had a strong overall effect on tree communities, with an average fire frequency (one fire every three years) reducing stem density by 48% and basal area by 53% after 50 years, relative to unburned plots. The largest changes occurred in savanna ecosystems and in sites with strong wet seasons or strong dry seasons, pointing to fire characteristics and species composition as important. Analyses of functional traits highlighted the impact of fire-driven changes in soil nutrients because frequent burning favoured trees with low biomass nitrogen and phosphorus content, and with more efficient nitrogen acquisition through ectomycorrhizal symbioses. Taken together, the response of trees to altered fire frequencies depends both on climatic and vegetation determinants of fire behaviour and tree growth, and the coupling between fire-driven nutrient losses and plant traits

Metabolic Rift or Metabolic Shift? Dialectics, Nature, and the World-Historical Method

Abstract In the flowering of Red-Green Thought over the past two decades, metabolic rift thinking is surely one of its most colorful varieties. The metabolic rift has captured the imagination of critical environmental scholars, becoming a shorthand for capitalism’s troubled relations in the web of life. This article pursues an entwined critique and reconstruction: of metabolic rift thinking and the possibilities for a post-Cartesian perspective on historical change, the world-ecology conversation. Far from dismissing metabolic rift thinking, my intention is to affirm its dialectical core. At stake is not merely the mode of explanation within environmental sociology. The impasse of metabolic rift thinking is suggestive of wider problems across the environmental social sciences, now confronted by a double challenge. One of course is the widespread—and reasonable—sense of urgency to evolve modes of thought appropriate to an era of deepening biospheric instability. The second is the widely recognized—but inadequately internalized—understanding that humans are part of nature

A Net Energy Analysis of the Global Agriculture, Aquaculture, Fishing and Forestry System

The global agriculture, aquaculture, fishing and forestry (AAFF) energy system is subject to three unsustainable trends: (1) the approaching biophysical limits of AAFF; (2) the role of AAFF as a driver of environmental degradation; and (3) the long-term declining energy efficiency of AAFF due to growing dependence on fossil fuels. In response, we conduct a net energy analysis for the period 1971–2017 and review existing studies to investigate the global AAFF energy system and its vulnerability to the three unsustainable trends from an energetic perspective. We estimate the global AAFF system represents 27.9% of societies energy supply in 2017, with food energy representing 20.8% of societies total energy supply. We find that the net energy-return-on-investment (net EROI) of global AAFF increased from 2.87:1 in 1971 to 4.05:1 in 2017. We suggest that rising net EROI values are being fuelled in part by ‘depleting natures accumulated energy stocks’. We also find that the net energy balance of AAFF increased by 130% in this period, with at the same time a decrease in both the proportion of rural residents and also the proportion of the total population working in AAFF—which decreased from 19.8 to 10.3%. However, this comes at the cost of growing fossil fuel dependency which increased from 43.6 to 62.2%. Given the increasing probability of near-term fossil fuel scarcity, the growing impacts of climate change and environmental degradation, and the approaching biophysical limits of global AAFF, ‘Odum’s hoax’ is likely soon to be revealed