The effects of predator presence on insect behavior: consequences for individual fitness, population growth and pest suppression in agroecosystems

Organisms respond to the presence of foraging predators with a variety of antipredator strategies including escape responses, microhabitat shifts, and the restriction of conspicuous activities such as movement, foraging, and reproduction. Although these effects have been well-documented in aquatic systems, relatively little information is available about their impacts in terrestrial systems. In addition, because conceptual models of predator-prey interactions form the basis of our understanding of pest suppression in agroecosystems, information regarding the impact of predator presence on economically important pest insects may help us to better understand the qualities embodied by successful biological control agents. In this two-part study, I examined the impacts of predator presence on the feeding activity of insects in garden test systems. In the first part, a series of experiments paired pest insects with single, spider species to measure the relative contributions of direct mortality and predator-induced reductions of feeding activity to reductions in crop damage. Direct mortality accounted for approximately 15% of the observed reduction in crop damage while predator-presence effects accounted for an additional 10-40% depending on the system. In the second part of this study, I present a detailed examination of a single system in which predator-presence effects proved to be important. An individual-based computer simulation of the fifth larval instar of the small, white cabbage butterfly, Pieris rapae L. was developed in conjunction with Dr. Gary Huxel of the University of California at Davis. This simulation incorporated experimentally-derived estimates of feeding activity and growth under predation pressure. The simulation was nm at three different predator densities to evaluate the impact of predator-presence effects on population growth. At high densities, predators significantly lengthen the maturation time for fifth-instar P. rapae larvae resulting in probable losses of fitness and slowed population growth. These effects are discussed within the context of their ecological and evolutionary significance, as well as their implications for the biological control of insect pests in agroecosystems

Electronic ticketing systems as a mechanism for travel behaviour change? Evidence from Sydney’s Opal Card

Smartcard and other forms of electronic ticketing have become integral to modern public transport systems. While aggregate ridership figures have generally been positive, little is known about the drivers behind these changes because of a lack of travel information on individuals before and after implementation of such systems. This working paper presents analysis from a naturalistic travel behaviour study of inner-city Sydney residents that coincided with the phased introduction of the Opal smartcard system. Using a differences-in-differences methodology, results indicate significant reductions in car use of around 10 minutes/day with commensurate increases in train use and incidental walking. This trend holds across income groups and is more pronounced for older residents. Results add further weight to the merits of simplifying ticket purchasing as part of a package of policy measures designed to increase public transport usage

Aero engine compressor cooling by water injection - Part 2: Performance and emission reductions

Take-off and climb up to 3000 ft are the flight segments in which the aero-engine experiences the highest operating temperatures, which are known to be accompanied by a high production rate of Nitrogen Oxides (NOx). This contaminant has negative health implications on the human population, vegetation and wildlife that is in frequent proximity or exposure. Water injection into the compressor offers the possibility of reducing NOx. Nevertheless, limited studies have focused on the emissions reduction potentials and the wider questions of the influence of engine type and of wide-ranging ambient conditions. This study continues from Part 1 and explores the implications of the studied ambient conditions on the overall respective engine systems and their consequent emission reduction. An in-house gas turbine performance simulation software has been implemented to model and simulate the engine performance. For the emissions estimation, correlations were made from the information provided by the Engine Emissions Data Bank to quantify the reductions in Nitrogen Oxides. The 2 and 3-spool engine models investigated demonstrated significant reductions in compressor discharge and turbine inlet temperatures due to water injection. In this condition, the rotational speeds of the compressors are seen to be reduced to counter the mass flow augmenting effect of water injection and to satisfy the fixed thrust constraint. This along with lower compressor specific work brings about an improvement in the specific fuel consumption (5.3% and 7.8%, respectively) and general performance at low and high ambient temperatures. A higher advantage was seen for the 3-spool engine over the 2-spool as shown. Significant reductions in Nitrogen Oxide emissions of over to 50% are also demonstrated

Power Sector Opportunities for Reducing Carbon Dioxide Emissions: Colorado

President Obama announced a national climate plan in June 2013 and directed the U.S. Environmental Protection Agency (EPA) to set carbon pollution standards for the power sector. Once EPA establishes those standards, states will implement their own plans for achieving those reductions. In this fact sheet, WRI examines existing tools Colorado can use to reduce power plant emissions

Automated Circuit Diagnosis using First Order Logic Tools

While Numerous Diagnostic Expert Systems Have Been Successfully Developed in Recent Years, They Are Almost Uniformly based on Heuristic Reasoning Techniques (I.e., Shallow Knowledge) in the Form of Rules. This Paper Reports on an Automated Circuit Diagnostic Tool based on Reiter\u27s Theory of Diagnosis. in Particular, this is a Theory of Diagnosis based on Deep Knowledge (I.e., Knowledge based on Certain Design Information) and using First Order Logic as the Representation Language. the Inference Mechanism Which is Incorporated as Part of the Diagnostic Tool is a Refutation based Theorem Prover using Rewriting Systems for Boolean Algebra Developed by Hsiang. Consequently, the Diagnostic Reasoning Tool is Broadly based on Reiter\u27s Model but Incorporates Complete Sets of Reductions for Boolean Algebra to Reason over Equa-Tional Descriptions of the Circuits to Be Analyzed. the Refutational Theorem Prover Uses an Associative Commutative Identity Unification Algorithm Described by Hsiang but Requires Additional Focusing Techniques in Order to Be Appropriate for Diagnosing Circuits. a Prototype Version of the Mainline Diagnostic Program Has Been Developed and Has Been Successfully Demonstrated on Several Small but Nontrivial Combinational Circuit Examples

Can the U.S. Get There from Here?

Climate change impacts in the United States are increasingly evident and come with steep economic and social costs. The frequency and intensity of extreme weather events has increased in recent years, bringing record-breaking heat, heavy precipitation, coastal flooding, severe droughts, and damaging wildfires.According to the National Oceanic and Atmospheric Administration (NOAA), weather-related damages in the United States were $60 billion in 2011, and are expected to be significantly greater in 2012.The mounting costs convey an unmistakable urgency to address climate change by reducing greenhouse gas emissions (GHGs). This report examines pathways for GHG reductions in the United States through actions taken at the federal and state levels without the need for new legislation from the U.S. Congress

Power Sector Opportunities for Reducing Carbon Dioxide Emissions: Illinois

President Obama announced a national climate plan in June 2013 and directed the U.S. Environmental Protection Agency (EPA) to set carbon pollution standards for the power sector. Once EPA establishes those standards, states will implement their own plans for achieving those reductions. In this fact sheet, WRI examines existing tools Illinois can use to reduce power plant emissions

Power Sector Opportunities for Reducing Carbon Dioxide Emissions: Minnesota

President obama announced a national climate plan in June 2013 and directed the U.S. Environmental Protection agency (EPa) to set carbon pollution standards for the power sector. once EPa establishes those standards, states will implement their own plans for achieving those reductions. In this fact sheet, WRI examines existing tools Minnesota can use to reduce power plant emissions