Regional methods for evaluating the effects of flow alteration on stream ecosystems

2012 Summer.Includes bibliographical references.Three stand-alone chapters explore the development and implementation of regional flow-ecology methods. Ecohydrology is an interdisciplinary field that brings together specialized research in hydrology, hydraulics, geomorphology and ecology. My dissertation reflects the need for interdisciplinary knowledge, tackling issues as diverse as low flows for trout (Chapter 2) to peak flows for cottonwood (Chapter 3). A regional-scale view unifies these investigations, with Chapter 1 establishing the scientific foundation and management objectives for regional flow-ecology methods. Summary Chapter 1 - To balance the benefits of dams and water diversions against society's expectations for the natural environment, flow managers require scientific advice on the ecosystem response to flow alteration. The methods selected to investigate the ecosystem effects of flow alteration (e.g., PHABSIM - Physical Habitat Simulation) should reflect the scale of flow management and the information requirements of flow managers. In addition, a hierarchical habitat framework provides an ecological foundation for the development and implementation of flow-ecology methods, because ecosystem response to flow is constrained by large-scale processes. This can be put into practice using hydrogeomorphic classification to define the higher-level physical processes (e.g., sediment transport, disturbance) that dictate the mechanisms of biotic response to flow. Regional flow-ecology methods provide a vehicle for incorporating prior knowledge and hydrogeomorphic processes into flow management at both regional and local scales. Chapter 2 - Changes in hydraulic habitat (depth and velocity) with flow can be predicted using intensive reach-specific methods, such as PHABSIM. I used existing PHABSIM data to develop GHMs (Generalized Habitat Models) that predict trout habitat-flow curves for unsurveyed streams of the southern Rocky Mountains. Predicted habitat was significantly correlated with the abundance of large brown trout (P40% flow reduction). Historic photographs revealed that narrowleaf in the Middle Park area (Colorado) have increased in abundance since dam closure, colonizing previously bare gravel bars. That narrowleaf appear less sensitive to flow alteration than plains cottonwood could reflect different species traits (e.g., alternative sources of disturbance for root suckering by narrowleaf), together with the many physical transitions from plains to mountains that are associated with the species transition

Enthalpies of formation of lanthanide oxyapatite phases

A family of lanthanide silicates adopts an oxyapatite-like structure with structural formula Ln9.33∎0.67(SiO4)6O2 (Ln 4 La, Sm, Nd, Gd, ∎ = vacancy). The enthalpies of solution, DHS, for these materials and their corresponding binary oxides were determined by high-temperature oxide melt solution calorimetry using molten 2PbO·B2O3 at 1078 K. These data were used to complete thermodynamic cycles to calculate enthalpies of formation from the oxides, ΔHs f-oxides (kJ/mol): La9.33∎0.67(SiO4)6O2 = −776.3 ± 17.9, Nd9.33∎0.67(SiO4)6O2 = −760.4 ± 31.9, Sm9.33∎0.67(SiO4)6O2 = −590.3 ± 18.6, and Gd9.33∎0.67(SiO4)6O2 = −446.9 ± 21.9. Reference data were used to calculate the standard enthalpies of formation from the elements, ΔH0 f (kJ/mol): La9.33∎0.67(SiO4)6O2 = −14611.0 ± 19.4, Nd9.33∎0.67(SiO4)6O2 = −14661.5 ± 32.2, Sm9.33∎0.67(SiO4)6O2 = −14561.7 ± 20.8, and Gd9.33∎0.67(SiO4)6O2 = −14402.7 ± 28.2. The formation enthalpies become more endothermic as the ionic radius of the lanthanide ion decreases

Chain length dependence of the polymer-solvent critical point parameters

We report grand canonical Monte Carlo simulations of the critical point properties of homopolymers within the Bond Fluctuation model. By employing Configurational Bias Monte Carlo methods, chain lengths of up to N=60 monomers could be studied. For each chain length investigated, the critical point parameters were determined by matching the ordering operator distribution function to its universal fixed-point Ising form. Histogram reweighting methods were employed to increase the efficiency of this procedure. The results indicate that the scaling of the critical temperature with chain length is relatively well described by Flory theory, i.e. \Theta-T_c\sim N^{-0.5}. The critical volume fraction, on the other hand, was found to scale like \phi_c\sim N^{-0.37}, in clear disagreement with the Flory theory prediction \phi_c\sim N^{-0.5}, but in good agreement with experiment. Measurements of the chain length dependence of the end-to-end distance indicate that the chains are not collapsed at the critical point.Comment: 13 Pages Revtex, 9 epsf embedded figs. gzipped tar file. To appear in J. Chem. Phy

The universality class of the electroweak theory

We study the universality class and critical properties of the electroweak theory at finite temperature. Such critical behaviour is found near the endpoint m_H=m_{H,c} of the line of first order electroweak phase transitions in a wide class of theories, including the Standard Model (SM) and a part of the parameter space of the Minimal Sypersymmetric Standard Model (MSSM). We find that the location of the endpoint corresponds to the Higgs mass m_{H,c} = 72(2) GeV in the SM with sin^2 theta_W = 0, and m_{H,c} < 80 GeV with sin^2 theta_W = 0.23. As experimentally m_H > 88 GeV, there is no electroweak phase transition in the SM. We compute the corresponding critical indices and provide strong evidence that the phase transitions near the endpoint fall into the three dimensional Ising universality class.Comment: 35 pages, 15 figure

Exploratory and Collaborative Learning Scenarios in Virtual World using Unity-based Technology

This paper focuses on learning tools developed for the integration in virtual learning worlds that enable instructors to create in-world scenarios more easily. The tools were implemented in consideration of several learning concepts on exploratory, collaborative and challenge-based approaches. It elaborates on the design and development of a virtual world project on two platforms, namely Unity and Open Wonderland which is based on an Egyptian learning world. Users explore the world to find, explore and discard information. Through the process of identification and elimination a story is formed. Users can share information and collaborate with other users in- world and the tasks are supported by tools embedded in the virtual world, such as Textchat, Itemboard and Chatbot. The virtual world in Unity has addressed some of the issues raised in Open Wonderland such as the graphics enhancements, level of interactivities and lessons learned from the first prototype

Housing works : assessing the impact of housing association employment support

Social housing providers in the UK have a long history of delivering support to their residents beyond housing, including providing employment related assistance. A small but growing area of research investigates the role of employment support outside the mainstream welfare system. However, little is known about the support provided, the impact it has on individuals’ prospects in the labour market, and related outcomes for housing providers, the taxpayer and wider society. As increasing numbers of people are expected to engage in work search and other work preparation activities in exchange for continued receipt of welfare benefits, the impact of housing provider employment support needs to be better understood. The membership of Give us a Chance (GUAC) have, as housing associations, been involved in a range of initiatives to improve the employment and life chance outcomes of their residents, including working with employment support organisations and the voluntary and community sector. However, there is considerable variation in the way that housing association employment support is currently provided, and a wide range of tools and measures are used to show the value of these initiatives, from specific organisational measures through to more generic approaches, such as the Housing Associations’ Charitable Trust (HACT) measures and the New Economy Cost Benefit Analysis (CBA) model. Hence, it is often difficult to compare the value of projects based on different approaches and measured using different tools. This research had two key aims: to contribute to an understanding of what helps people to move closer to, enter or sustain employment and to demonstrate the value of housing association investment in employment related support for residents. The project had the following linked objectives: 1. Provide a review of housing association employment related support activity; 2. Undertake a review of the impact measures currently used for employment related support across the social housing sector; and 3. Provide an understanding of ‘what works’ in terms of employment related support and the measures used among GUAC members

Density depletion and enhanced fluctuations in water near hydrophobic solutes: identifying the underlying physics

We investigate the origin of the density depletion and enhanced density fluctuations that occur in water in the vicinity of an extended hydrophobic solute. We argue that both phenomena are remnants of the critical drying surface phase transition that occurs at liquid-vapor coexistence in the macroscopic planar limit, ie. as the solute radius $R_s\to\infty$. Focusing on the density profile $\rho(r)$ and a sensitive spatial measure of fluctuations, the local compressibility profile $\chi(r)$, we develop a scaling theory which expresses the extent of the density depletion and enhancement in compressibility in terms of $R_s$, the strength of solute-water attraction $\varepsilon_s$, and the deviation from liquid-vapor coexistence $\delta\mu$. Testing the predictions against results of classical density functional theory for a simple solvent and Grand Canonical Monte Carlo simulations of a popular water model, we find that the theory provides a firm physical basis for understanding how water behaves at a hydrophobe.Comment: 5 pages, 4 figures. To appear in Phys. Rev. Let