Introduction

Vertebrate species have been introduced to almost all parts of the world for thousands of years. Within the United States and its territories alone, over 1000 vertebrate species have been introduced since the early sailing ships explored the world. This includes at least 86 species of mammals, 127 species of birds, 126 species of reptiles, 53 species of amphibians, and over 673 species of fish (Witmer and Fuller 2011). Many of these species were native to the United States, but were moved to novel regions, often unintentionally or intentionally by humans. While invasive vertebrates have been introduced to all parts of the world, in this book, we focus on introduced terrestrial vertebrates in the United States and its territories, and the intention is to provide an overview of the complexity and challenges associated with managing invasive species within the United States. Often, the management of invasive species and the prevention of new species becoming established is largely a function of the regulatory framework established within a specific country. In this book, although historical management successes and failures are discussed, the focus is on current effective management options and potential future developments to minimize the effects of invasive species and prevent their spread into new areas. Although plants and animals have been introduced into new areas for centuries, the increased volume of worldwide trade and transportation has accelerated the rate of species introductions over the last 150 years. Animals are introduced for many reasons, both purposeful and accidental. Intentional introductions include both legal and illegal activities such as the production of food and fur, work animals, sport hunting opportunities, companion animals, aesthetics, pets, pet trade propagation, religious purposes, and pest control. Accidental introductions occur because of stowaways in transport vehicles, hitchhikers or stowaways in or on other commodities, escapees, and, in some cases, because of range expansion of a species, often facilitated by human activities and land use. For example, a tropical storm is thought to have brought the cattle egret Bubulcus ibis to North America (Florida initially) from the Caribbean islands after they had crossed the Atlantic Ocean from Europe and Africa. However, it may have been agricultural land use that allowed its subsequent rapid range expansion westward across North America. Likewise, habitat fragmentation stemming from anthropogenic land use has facilitated the expansion of coyotes (Canis latrans) across the Eastern United States and far south into Central America over the last several decades, reaching areas where the species formerly did not occur

An individual-based model of canid populations: modelling territoriality and social structure

The management of canid populations has been at the forefront of wildlife management worldwide for much of the last century. Effective management depends on the ability to integrate species biology, the environmental aspects upon which those populations depend, and the factors controlling species abundance. Further, managing canid populations requires consideration of territoriality and dominance, which may have a significant effect on population dynamics. To better understand the effect of social structure on canid populations, we developed an individual-based computer model using Swarm to mimic natural coyote population dynamics. We selected the Swarm simulation environment because it is ideally suited for creating a system of multiple interacting agents with variable schedules and hierarchies. Swarm was a software platform that allows the user to describe generic individuals and behaviours, link those behaviours in each concurrent time step, and assemble behaviours and objects in a hierarchical framework. This model stands apart from previous modelling efforts because it explicitly incorporates behavioral features, such as dominance and territoriality, as major determinates of species demography into a simple model. Individual variation, such as status within territorial social groups and age-based reproduction are incorporated, but assumptions typically associated with most demographic models are not needed. The simple population model with few parameters not only closely resembled ‘real world’ populations but also helped us understand population dynamics that emerged from model. The sensitivity analysis revealed that the model was largely insensitive to individual parameter estimates and could be used to guide management of territorial animal populations with social structure. The model output variables closely matched the mean and range of values reported in the literature of wild populations for population size, proportion of females breeding, offspring survival and litter size. The variation of model output was similar to the variation recorded in field studies. Further, population dynamics reported from field studies emerged from the model and may help to explain the mechanisms responsible for this variation. This type of model could also provide insights into potential management alternatives for other canid species or other species with similar social structure

Foreword

The effects of invasive vertebrate species on agriculture, human health and safety, and the environment are a growing concern around the world. The number of incidents of invasive species causing harm continues to climb with increased worldwide travel and transportation of goods. The focus for many decades was on invasive pathogens, plants, and invertebrates because they can greatly affect human and animal health and food supplies. In recent years, invasive vertebrate species, such as rats, feral pigs, and feral cats, have garnered more attention because the magnitude of their impacts have been repeatedly highlighted in the media. In response, better methods of prevention, detection, and management of invasive species have been developed. For example, several eradications of invasive vertebrates on islands have been successful, although management on mainland settings is generally much more challenging

A New Approach to Understanding Canid Populations Using an Individual-based Computer Model: Preliminary Results

Ensuring the welfare of wild canid populations depends upon the ability to integrate species biology, the environmental aspects upon which those populations depend, and the factors controlling species abundance. Toward this end, we developed an individual-based computer model using Swarm to mimic natural coyote populations. Swarm is a software platform that allows the user to describe individual behaviors for all individuals, link those behaviors in each concurrent time step, and assemble behaviors and objects in a hierarchical framework. Our model stands apart from previous modeling efforts because it relies on field data and explicitly incorporates behavioral features, such as dominance and territoriality, as major determinates of species demography. Individual variation, such as status within territorial social groups and age-based reproduction are assumed, but assumptions typically associated with most demographic models are not needed. The eventual goal is to incorporate other environmental components such as prey abundance and/or competing carnivores. This type of model could also provide insights into potential management alternatives for when the gray wolf is removed from endangered status in Minnesota

Evaluating the effects of management on territorial populations using Swarm

For centuries, coyotes have been controlled to protect livestock and/or enhance game populations. The intensity of control has varied widely and many types of control techniques have been used. The effects of these control techniques need to be evaluated to effectively resolve conflicts among agencies and interest groups, to fulfill legal requirements, and to aid the development of new strategies for managing populations. However, the influence of these techniques on coyote population size and structure is largely unknown. Furthermore, management decisions are often required before experimental tests can be developed and conducting requisite experimental programs on meaningful scales are logistically prohibitive. Therefore, we developed an individual-based computer model using Swarm to evaluate the effects of various control techniques on age structure including selective removal, random removal, and denning. This model is part of a larger effort to fully evaluate the effect of current management strategies on coyote populations and to eventually link this population model to a depredation model. Selective and random removal resulted in younger age structures, whereas denning produced population age structures similar to an unexploited population

Investigations in Gallium Removal

Gallium present in weapons plutonium must be removed before it can be used for the production of mixed-oxide (MOX) nuclear reactor fuel. The main goal of the preliminary studies conducted at Texas A and M University was to assist in the development of a thermal process to remove gallium from a gallium oxide/plutonium oxide matrix. This effort is being conducted in close consultation with the Los Alamos National Laboratory (LANL) personnel involved in the development of this process for the US Department of Energy (DOE). Simple experiments were performed on gallium oxide, and cerium-oxide/gallium-oxide mixtures, heated to temperatures ranging from 700--900 C in a reducing environment, and a method for collecting the gallium vapors under these conditions was demonstrated

The Application of Ultrasonics in Non-Destructive Testing: A Review of Some of the Research at University College London

This paper presents a review of some of the research projects at University College London which use ultrasonic waves in non-destructive testing. The projects covered include a low-frequency scanning acoustic microscope, a new dark-field acoustic microscope, an update on finite difference model studies of wave propagation and scattering, developments in mode-conversion techniques for defect characterisation, a new high-resolution acoustic field sampling probe and a resume of the work on Zn0 transducers

Hydrodynamic dispersion within porous biofilms

Many microorganisms live within surface-associated consortia, termed biofilms, that can form intricate porous structures interspersed with a network of fluid channels. In such systems, transport phenomena, including flow and advection, regulate various aspects of cell behavior by controlling nutrient supply, evacuation of waste products, and permeation of antimicrobial agents. This study presents multiscale analysis of solute transport in these porous biofilms. We start our analysis with a channel-scale description of mass transport and use the method of volume averaging to derive a set of homogenized equations at the biofilm-scale in the case where the width of the channels is significantly smaller than the thickness of the biofilm. We show that solute transport may be described via two coupled partial differential equations or telegrapher's equations for the averaged concentrations. These models are particularly relevant for chemicals, such as some antimicrobial agents, that penetrate cell clusters very slowly. In most cases, especially for nutrients, solute penetration is faster, and transport can be described via an advection-dispersion equation. In this simpler case, the effective diffusion is characterized by a second-order tensor whose components depend on (1) the topology of the channels' network; (2) the solute's diffusion coefficients in the fluid and the cell clusters; (3) hydrodynamic dispersion effects; and (4) an additional dispersion term intrinsic to the two-phase configuration. Although solute transport in biofilms is commonly thought to be diffusion dominated, this analysis shows that hydrodynamic dispersion effects may significantly contribute to transport

The GLM-spectrum:A multilevel framework for spectrum analysis with covariate and confound modelling

The frequency spectrum is a central method for representing the dynamics within electrophysiological data. Some widely used spectrum estimators make use of averaging across time segments to reduce noise in the final spectrum. The core of this approach has not changed substantially since the 1960s, though many advances in the field of regression modelling and statistics have been made during this time. Here, we propose a new approach, the General Linear Model (GLM) Spectrum, which reframes time averaged spectral estimation as multiple regression. This brings several benefits, including the ability to do confound modelling, hierarchical modelling, and significance testing via non-parametric statistics. We apply the approach to a dataset of EEG recordings of participants who alternate between eyes-open and eyes-closed resting state. The GLM-Spectrum can model both conditions, quantify their differences, and perform denoising through confound regression in a single step. This application is scaled up from a single channel to a whole head recording and, finally, applied to quantify age differences across a large group-level dataset. We show that the GLM-Spectrum lends itself to rigorous modelling of within- and between-subject contrasts as well as their interactions, and that the use of model-projected spectra provides an intuitive visualisation. The GLM-Spectrum is a flexible framework for robust multilevel analysis of power spectra, with adaptive covariate and confound modelling

Going places

Journeys. We all make them. Often they take us to exotic places. Sometimes they take us even further. They might take us through time. Or they might take us into a new way of life. There are times too, when we go all over the world and back again only to find that home is, after all, where it’s all happening. This book contains stories about many different types of journey. We hope you will enjoy travelling into it and finding a world that suits you