Busted by the bite

Large herbivores are charismatic species known to engineer ecosystems through a variety of effects. Conflicts can sometimes arise when these effects are undesirable. However, without detailed knowledge on herbivore selectivity for landscapes, patches and plants, these positive and negative effects remain difficult to predict. Such species and sex-specific selectivity have inherent evolutionary and ecological mechanisms. In order to study such mechanisms it is important to study the partitioning of resources at multiple scales. Most studies have looked at large-scale resource partitioning (such as movement patterns) but fewer study the fine-scale levels of selectivity such as the individual bites taken by herbivores. This level of detail is, however, important because it is essentially the direct mechanism through which ecosystem effects are manifested. Specifically for the browsing herbivore guild, such fine-scale studies have largely been impractical due to forested habitats which limit direct observation of behaviors. DNA-based diagnostics are becoming more and more popular within ecology as they provide vital data to answer certain questions. In this thesis I developed two versions of a method to differentiate between five species of large herbivore browsers using trace amounts of environmental DNA left at browsed twigs. The first version uses a traditional amplification method for identifying the species of browsers and the second uses an advanced and more sensitive method for identifying the species and sex of browsers. Using environmental DNA, I determined species-specific browsing patterns across three studies. I found overall that traditional methods for attributing browsing at the species level tend to be misleading. In one study I show that although one species may be blamed for forest plantation damages, DNA evidence showed a partitioning between three herbivore species. I also document the partitioning of plant parts among different sized ungulates and show that overlap in browsing heights and bite diameters is much larger than previously assumed. In another study I experimentally verified the selectivities of free-ranging herbivores for three species of trees. This thesis thus not only develops new molecular ecological tools but also provides new insights into resource partitioning and hence the ecosystem effects of herbivores

Estimating exposure response functions using ambient pollution concentrations

This paper presents an approach to estimating the health effects of an environmental hazard. The approach is general in nature, but is applied here to the case of air pollution. It uses a computer model involving ambient pollution and temperature input to simulate the exposures experienced by individuals in an urban area, while incorporating the mechanisms that determine exposures. The output from the model comprises a set of daily exposures for a sample of individuals from the population of interest. These daily exposures are approximated by parametric distributions so that the predictive exposure distribution of a randomly selected individual can be generated. These distributions are then incorporated into a hierarchical Bayesian framework (with inference using Markov chain Monte Carlo simulation) in order to examine the relationship between short-term changes in exposures and health outcomes, while making allowance for long-term trends, seasonality, the effect of potential confounders and the possibility of ecological bias. The paper applies this approach to particulate pollution (PM10) and respiratory mortality counts for seniors in greater London (≥65 years) during 1997. Within this substantive epidemiological study, the effects on health of ambient concentrations and (estimated) personal exposures are compared. The proposed model incorporates within day (or between individual) variability in personal exposures, which is compared to the more traditional approach of assuming a single pollution level applies to the entire population for each day. Effects were estimated using single lags and distributed lag models, with the highest relative risk, RR=1.02 (1.01–1.04), being associated with a lag of two days ambient concentrations of PM10. Individual exposures to PM10 for this group (seniors) were lower than the measured ambient concentrations with the corresponding risk, RR=1.05 (1.01–1.09), being higher than would be suggested by the traditional approach using ambient concentrations

Plasma Wakefield Acceleration with a Modulated Proton Bunch

The plasma wakefield amplitudes which could be achieved via the modulation of a long proton bunch are investigated. We find that in the limit of long bunches compared to the plasma wavelength, the strength of the accelerating fields is directly proportional to the number of particles in the drive bunch and inversely proportional to the square of the transverse bunch size. The scaling laws were tested and verified in detailed simulations using parameters of existing proton accelerators, and large electric fields were achieved, reaching 1 GV/m for LHC bunches. Energy gains for test electrons beyond 6 TeV were found in this case.Comment: 9 pages, 7 figure

Efficient simulation of DC-DC switch-mode power converters by multirate partial differential equations

In this paper, Multirate Partial Differential Equations (MPDEs) are used for the efficient simulation of problems with 2-level pulsed excitations as they often occur in power electronics, e.g., DC-DC switch-mode converters. The differential equations describing the problem are reformulated as MPDEs which are solved by a Galerkin approach and time discretization. For the solution expansion two types of basis functions are proposed, namely classical Finite Element (FE) nodal functions and the recently introduced excitation-specific pulse width modulation (PWM) basis functions. The new method is applied to the example of a buck converter. Convergence, accuracy of the solution and computational efficiency of the method are numerically analyzed

Solving nonlinear circuits with pulsed excitation by multirate partial differential equations

In this paper the concept of Multirate Partial Differential Equations (MPDEs) is applied to obtain an efficient solution for nonlinear low-frequency electrical circuits with pulsed excitation. The MPDEs are solved by a Galerkin approach and a conventional time discretization. Nonlinearities are efficiently accounted for by neglecting the high-frequency components (ripples) of the state variables and using only their envelope for the evaluation. It is shown that the impact of this approximation on the solution becomes increasingly negligible for rising frequency and leads to significant performance gains.Comment: 4 pages, 7 figures, approved for publication in IEEE Transactions on Magnetic

Innovations in irrigation financing

"Financing for water projects, especially for irrigation, has been moving towards collapse in recent years due to declining donor and government funding. Some Indian states have undertaken innovative institutional reforms by setting up financially autonomous corporations to mobilise required funds from the domestic bond market. This analysis of the performance of one such corporation, Karnataka's Krishna Bhagya Jal Nigam Limited, indicates that although adequate funds were mobilised, and physical works are on schedule, the new institution did not attempt to enhance overall irrigation performance and to move towards financial sustainability of the irrigation project. This paper describes the background of this institution, its achievements, inadequacies and potential of the innovative efforts made in irrigation financing reforms." Authors' AbstractIrrigation India ,Irrigation projects India ,Finance ,Government spending policy ,

Multiscale Finite Element Modeling of Nonlinear Magnetoquasistatic Problems Using Magnetic Induction Conforming Formulations

In this paper we develop magnetic induction conforming multiscale formulations for magnetoquasistatic problems involving periodic materials. The formulations are derived using the periodic homogenization theory and applied within a heterogeneous multiscale approach. Therefore the fine-scale problem is replaced by a macroscale problem defined on a coarse mesh that covers the entire domain and many mesoscale problems defined on finely-meshed small areas around some points of interest of the macroscale mesh (e.g. numerical quadrature points). The exchange of information between these macro and meso problems is thoroughly explained in this paper. For the sake of validation, we consider a two-dimensional geometry of an idealized periodic soft magnetic composite.Comment: Paper accepted for publication in the SIAM MMS journa

California Arbitration Reform: The Aftermath

NOT TOO LONG ago, the only mandatory pre-dispute arbitration clause imposed on consumers was found in documents used to open an account in a securities brokerage firm or in a contract that Kaiser Permanente patients must sign in order to receive medical treatment. Today these imposed arbitration clauses are found everywhere, forcing individuals to forgo a civil lawsuit and pursue any legal action through arbitration. When you buy a house, take a job, open a bank account, receive health care, sign up for telecommunications service, and even purchase season football tickets, you may be required to accept a dispute resolution policy that includes mandatory arbitration. These provisions surrender your right to pursue a claim in court or be part of a class-action lawsui