Proactive or Reactive? Optimal Management of an Invasive Forest Pest in a Spatial Framework

This paper offers a preliminary investigation into the conditions under which it might be optimal to engage in proactive management of a non-timber forest resource in the presence of an invasive species whose spread is unaffected by management action. Proactive management is defined as treating an uninfected area in order to encourage healthy ecosystem function, given that the arrival of the invasive is inevitable. Inspired by the problem of white pine blister rust in the Rocky Mountain west, the model was solved under varying assumptions concerning the scale of management action, benefit and costs, the discount rate, and uncertainty of spread. Results showed that proactive strategies tended to be optimal when, ceteris paribus, a) more resources are available for treatment; b) the costs of treatment are rapidly increasing in forest health, or conversely, the benefits of healthy and unhealthy stands are relatively similar; and c) the discount rate is low. The introduction of uncertainty did not significantly affect the likelihood of a proactive management strategy being optimal, but did show that the conditional probabilities of infection play important role in the decision of which uninfected stand should be treated if a choice is available to the manager.Crop Production/Industries, Resource /Energy Economics and Policy,

The Evolution of the Cosmic Microwave Background

We discuss the time dependence and future of the Cosmic Microwave Background (CMB) in the context of the standard cosmological model, in which we are now entering a state of endless accelerated expansion. The mean temperature will simply decrease until it reaches the effective temperature of the de Sitter vacuum, while the dipole will oscillate as the Sun orbits the Galaxy. However, the higher CMB multipoles have a richer phenomenology. The CMB anisotropy power spectrum will for the most part simply project to smaller scales, as the comoving distance to last scattering increases, and we derive a scaling relation that describes this behaviour. However, there will also be a dramatic increase in the integrated Sachs-Wolfe contribution at low multipoles. We also discuss the effects of tensor modes and optical depth due to Thomson scattering. We introduce a correlation function relating the sky maps at two times and the closely related power spectrum of the difference map. We compute the evolution both analytically and numerically, and present simulated future sky maps.Comment: 23 pages, 11 figures; references added; one figure dropped and minor changes to match published version. For high-resolution versions of figures and animations, see http://www.astro.ubc.ca/people/scott/future.htm

The process of responding to personality items: Inconsistent responses to repeated presentation of identical items

A promising approach to understanding the processes involved when subjects respond to personality items is provided by the investigation of the causes of inconsistent responses when subjects answer the same item on two occasions. Among these causes are the properties of the item. Previous item research focused almost exclusively on properties which are not highly specific to the item, such as endorsement rate (ER) and social desirability scale value (SDSV). Although past studies found that items with `extreme' SDSVs and/or ERs elicit fewer inconsistencies, these studies ignored more item-specific properties such as item content and item ambiguity. The present study demonstrates that contrary results regarding consistency may be obtained when more item-specific properties are taken into consideration. These results are interpreted as evidence that certain kinds of item content can increase the indecision and conflict that characterize some subjects' response processes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26953/1/0000519.pd

Investigation into Nanocomposites for Applications in Lightning Strike Protection

The United States Air Force is continually researching ways to reduce costs associated with aircraft maintenance and improve operational safety. This study focuses on creating a systems engineering process to develop an Integrated Structural Health Monitoring System (ISHMS). The overarching process was then applied to design a conceptual ISHMS for a real-world scenario involving the F-15. Sensor selection, integration and testing were explored in detail using frequency response methods to detect structural damage. Testing was accomplished using a simplified structural specimen with Monitoring & Evaluation Technology Integration System (METIS) disk nodes attached at various locations. Two different METIS disk operation modes were utilized; pulse-echo and pitch-catch. Simulated and actual damage were introduced to the specimen allowing comparison between baseline and damaged tests. Comparative analysis validated the capabilities of frequency response sensors to detect damage. This analysis demonstrates that structural health monitoring systems using frequency response methods may be promising in the aerospace sector

Uranium(VI) Release from Contaminated Vadose Zone Sediments: Estimation of Potential Contributions from Dissolution and Desorption

A key difficulty in developing accurate, science-based conceptual models for remediation of contaminated field sites is the proper accounting of multiple coupled geochemical and hydrologic processes. An example of such a difficulty is the separation of desorption and dissolution processes in releasing contaminants from sediments to groundwaters; very few studies are found in the literature that attempt to quantify contaminant release by these two processes. In this study, the results from several extraction techniques, isotopic exchange experiments, and published spectroscopic studies were combined to estimate the contributions of desorption and dissolution to U(VI) release from contaminated sediments collected from the vadose zone beneath former waste disposal ponds in the Hanford 300-Area (Washington state). Vertical profiles of sediments were collected at four locations from secondary pond surfaces down to, and slightly below, the water table. In three of the four profiles, uranium concentration gradients were observed in the sediments, with the highest U concentrations at the top of the profile. One of the vertical profiles contained sediments with U concentrations up to 4.2x10-7 mol/g (100 ppm). U(VI) release to artificial groundwater solutions and extracts from these high-U concentrations sediments occurred primarily from dissolution of precipitated U(VI) minerals, including the mineral metatorbernite, [Cu(UO2PO4)2⋅8H2O]. At the bottom of this profile, beneath the water table, and in all three of the other profiles, U concentrations were \u3c5.88x10-8 mol/g (14 ppm), and U(VI) release to artificial groundwater solutions occurred primarily due to desorption of U(VI). When reacted in batch experiments with artificial groundwater solutions with compositions representative of the range of chemical conditions in the underlying aquifer, all samples released U(VI) at concentrations greater than regulatory limits within a few hours. A semi-mechanistic surface complexation model was developed to describe U(VI) adsorption on sediments collected from near the water table, as a function of pH, alkalinity, and Ca and U(VI) concentrations, using ranges in these variables relevant to groundwater conditions in the aquifer. Dilute (bi)carbonate solution extractions and uranium isotopic exchange methods were capable of estimating adsorbed U(VI) in samples where U(VI) release was predominantly due to U(VI) desorption; these techniques were not effective at estimating adsorbed U(VI) where U(VI) release was affected by dissolution of U(VI) minerals. The combination of extraction and isotopic exchange results, spectroscopic studies, and surface complexation modeling allow an adequate understanding for the development of a geochemical conceptual model for U(VI) release to the aquifer. The overall approach has generic value for evaluating the potential for release of metals and radionuclides from sediments that contain both precipitated and adsorbed contaminant speciation

Senior Theses: Department of Physical Sciences

1993 Fall Semester Senior Theses for the class Physical Science 471: Petrologic Classification of Igneous and Metamorphic Rocks by Frank Baldridge X -Ray Analysis of Cave Sediments From Pigeon Water Cave of Northeastern Pine Mountain by Billy B. Stapleton The Correlation of Stream-deposited Breccias In Bat Cave, Carter Caves, Kentucky by James Bond Jointing and Faulting in Selected Areas of Eastern Kentucky by Mark A. Blai

A New Extension of the Binomial Error Model for Responses to Items of Varying Difficulty in Educational Testing and Attitude Surveys

We put forward a new item response model which is an extension of the binomial error model first introduced by Keats and Lord. Like the binomial error model, the basic latent variable can be interpreted as a probability of responding in a certain way to an arbitrarily specified item. For a set of dichotomous items, this model gives predictions that are similar to other single parameter IRT models (such as the Rasch model) but has certain advantages in more complex cases. The first is that in specifying a flexible two-parameter Beta distribution for the latent variable, it is easy to formulate models for randomized experiments in which there is no reason to believe that either the latent variable or its distribution vary over randomly composed experimental groups. Second, the elementary response function is such that extensions to more complex cases (e.g., polychotomous responses, unfolding scales) are straightforward. Third, the probability metric of the latent trait allows tractable extensions to cover a wide variety of stochastic response processes

Determining Customary International Law Relative to the Conduct of Hostilities in Non-international Armed Conflicts

In 1987, the 6th annual American Red Cross-Washington College of Law Conference on International Humanitarian Law convened to discuss the 1977 Protocols Additional to the 1949 Geneva Conventions. This article outlines the proceedings of the various workshops, serving as a richly detailed scholarly source for a significant historical event