Partition Function Zeros of an Ising Spin Glass

We study the pattern of zeros emerging from exact partition function evaluations of Ising spin glasses on conventional finite lattices of varying sizes. A large number of random bond configurations are probed in the framework of quenched averages. This study is motivated by the relationship between hierarchical lattice models whose partition function zeros fall on Julia sets and chaotic renormalization flows in such models with frustration, and by the possible connection of the latter with spin glass behaviour. In any finite volume, the simultaneous distribution of the zeros of all partition functions can be viewed as part of the more general problem of finding the location of all the zeros of a certain class of random polynomials with positive integer coefficients. Some aspects of this problem have been studied in various branches of mathematics, and we show how polynomial mappings which are used in graph theory to classify graphs, may help in characterizing the distribution of zeros. We finally discuss the possible limiting set as the volume is sent to infinity.Comment: LaTeX, 18 pages, hardcopies of 15 figures by request to [email protected], CERN--TH-7383/94 (a note and a reference added

The Road to Stueckelberg's Covariant Perturbation Theory as Illustrated by Successive Treatments of Compton Scattering

We review the history of the road to a manifestly covariant perturbative calculus within quantum electrodynamics from the early semi-classical results of the mid-twenties to the complete formalism of Stueckelberg in 1934. We chose as our case study the calculation of the cross-section of the Compton effect. We analyse Stueckelberg's paper extensively. This is our first contribution to a study of his fundamental contributions to the theoretical physics of twentieth century.Comment: This paper is a "working-physicist" version of a paper to be published in Studies in History and Philosophy of Modern Physic

Restoration of Legacy Trees as Roosting Habitat for \u3cem\u3eMyotis\u3c/em\u3e Bats in Eastern North American Forests

Most eastern North American Myotis roost in forests during summer, with species forming maternity populations, or colonies, in cavities or crevices or beneath the bark of trees. In winter, these bats hibernate in caves and are experiencing overwinter mortalities due to infection from the fungus Pseudogymnoascus destructans, which causes white-nose syndrome (WNS). Population recovery of WNS-affected species is constrained by the ability of survivors to locate habitats suitable for rearing pups in summer. Forests in eastern North America have been severely altered by deforestation, land-use change, fragmentation and inadvertent introduction of exotic insect pests, resulting in shifts in tree distributions and loss of large-diameter canopy-dominant trees. This paper explores patterns in use of tree roosts by species of Myotis across Canada and the United States using meta-data from published sources. Myotis in western Canada, the Northwest, and Southwest selected the largest diameter roost trees and also supported the largest maximum exit counts. Myotis lucifugus, M. septentrionalis and M. sodalis, three species that inhabit eastern forests and which are currently experiencing region-wide mortalities because of WNS, selected roosts with the smallest average diameters. Recovery efforts for bark- and cavity-roosting Myotis in eastern North American forests could benefit from management that provides for large-diameter trees that offer more temporally-stable structures for roosting during the summer maternity season

Extracting information from non adiabatic dynamics: excited symmetric states of the Bose-Hubbard model

Using Fourier transform on a time series generated by unitary evolution, we extract many-body eigenstates of the Bose-Hubbard model corresponding to low energy excitations, which are generated when the insulator-superfluid phase transition is realized in a typical experiment. The analysis is conducted in a symmetric external potential both without and with and disorder. A simple classification of excitations in the absence disorder is provided. The evolution is performed assuming the presence of the parity symmetry in the system rendering many-body quantum states either symmetric or antisymmetric. Using symmetry-breaking technique, those states are decomposed into elementary one-particle processes.Comment: inv. talk at 5th Workshop on Quantum Chaos and Localization Phenomena, Warsaw 201

A Survey of Bats in Wayne National Forest, Ohio

Author Institution: Ohio Cooperative Wildlife Research Unit, The Ohio State UniversityDistribution, abundance, habitat selection, and activity of bats in Wayne National Forest, Ohio, were studied during the winters and summers of 1979 and 1980. Methods included winter surveys of abandoned mines and mist netting of riparian sites in summer. Four species of bats were found hibernating in 23 of 65 coal mine shafts examined, and big brown bats, Epteskus fuscus, were most abundant. Mines with long tunnel systems had significantly higher temperatures than those with shorter systems, but humidity did not differ between mine types. Big brown bats chose the cooler mines and in general showed the greatest tolerance of climatic extremes. Eight species of bats totaling 261 individuals were captured by mist netting at 163 riparian locations in 5 watersheds. Little brown bats, Myotis lucifugus, comprised 56% of all bats captured. Big brown bats (14%), eastern pipistrels, Pipistrellus subflavus (13%), and red bats, Lasiurus borealis (13%), were the next most abundant species in mist net samples. No Indiana bats, Myotis sodalis, were captured. Big brown bats preferred to forage in forested habitats. Activity for most species was highest soon after sunset, but activity in big brown bats peaked 0.5 hr later than in the other species

Effects of Reproductive Condition, Roost Microclimate, and Weather Patterns on Summer Torpor Use by a Vespertilionid Bat

A growing number of mammal species are recognized as heterothermic, capable of maintaining a high-core body temperature or entering a state of metabolic suppression known as torpor. Small mammals can achieve large energetic savings when torpid, but they are also subject to ecological costs. Studying torpor use in an ecological and physiological context can help elucidate relative costs and benefits of torpor to different groups within a population. We measured skin temperatures of 46 adult Rafinesque\u27s big-eared bats (Corynorhinus rafinesquii) to evaluate thermoregulatory strategies of a heterothermic small mammal during the reproductive season. We compared daily average and minimum skin temperatures as well as the frequency, duration, and depth of torpor bouts of sex and reproductive classes of bats inhabiting day-roosts with different thermal characteristics. We evaluated roosts with microclimates colder (caves) and warmer (buildings) than ambient air temperatures, as well as roosts with intermediate conditions (trees and rock crevices). Using Akaike\u27s information criterion (AIC), we found that different statistical models best predicted various characteristics of torpor bouts. While the type of day-roost best predicted the average number of torpor bouts that bats used each day, current weather variables best predicted daily average and minimum skin temperatures of bats, and reproductive condition best predicted average torpor bout depth and the average amount of time spent torpid each day by bats. Finding that different models best explain varying aspects of heterothermy illustrates the importance of torpor to both reproductive and nonreproductive small mammals and emphasizes the multifaceted nature of heterothermy and the need to collect data on numerous heterothermic response variables within an ecophysiological context

Effect of Reclamation Technique on Mammal Communitites Inhabiting Wetlands on Mined Lands in East-Central Ohio

Author Institution: Department of Forestry, University of Kentucky; Wildlife Technology Program and Department of Biology, The Pennsylvania State UniversityMammal communities were studied from May through August, 1988 to 1990, at four wetland sites in Coshocton and Muskingum counties, OH. Sites represented varying degrees of disturbance from mining activity and subsequent reclamation techniques, including a wetland constructed to treat mine water drainage. Each site was composed of a series of three cattail (Typba latifolid) cells for a balanced experimental design. Mammals were inventoried with snap trap removal grids and midday surveys for signs of activity. Mammal diversity and richness was highest at the constructed wetland and lowest at the site established with traditional reclamation procedures. Predictable patterns of land use disturbance for species presence/absence were observed with some alpha diversity (habitat specific) species being absent (i.e., tree squirrels) and gamma diversity (wide-ranging) species such as mustelids occurring rarely. Beta diversity species (habitat generalists) like woodchucks (Marmota monax) and white-tailed deer (Odocoileus virginianus) were common at all sites. The white-footed mouse (Peromyscus leucopus) was the small mammal captured most frequently, being the most abundant small mammal at the constructed wetland and the undisturbed site, with meadow voles (Microtus pennsylvanicus) most prevalent at the remaining sites. These results suggest that a wetland constructed for the treatment of mine water drainage can provide secondary benefits as habitat for a variety of mammal species

Shifts in Assemblage of Foraging Bats at Mammoth Cave National Park Following Arrival of White-Nose Syndrome

The arrival of white-nose syndrome (WNS) to North America in 2006, and the subsequent decline in populations of cave-hibernating bats have potential long-term implications for communities of forest-dwelling bats in affected regions. Severe declines in wintering populations of bats should lead to concomitant shifts in the composition and relative abundance of species during the staging, maternity, and swarming seasons in nearby forested habitats. We examined capture rates of bats collected in mist nets from 2009 to 2016 to evaluate summer patterns in abundance of species pre- and post-arrival of WNS to Mammoth Cave National Park, KY. The data demonstrated a significant change in overall relative abundances. Myotis septentrionalis (Northern Long-eared Myotis) was the most commonly captured species pre-WNS but declined to 18.5% of its original abundance. Nycticeius humeralis (Evening Bat), uncommonly caught in mist nets pre-WNS, demonstrated the largest increase in capture success following arrival of WNS to the Park, followed by Eptesicus fuscus (Big Brown Bat) and Lasiurus borealis (Eastern Red Bat). These data suggest that losses of cave-hibernating bats to WNS may be leading to a restructuring of foraging bat assemblages in nearby forested habitats, with species less affected by WNS potentially exploiting niche space vacated by bats succumbing to infection with WNS