Comparison of transcutaneous ultrasound over the right flank with transrectal ultrasonography in the diagnosis of pregnancy in New Zealand dairy herds : a thesis presented in partial fulfillment of the requirements for the degree of Master of Veterinary Science at Massey University

Application of a 3.5 MHz sector transducer over the right flank allows the rapid and clear visualization of bovine pregnancy (ie: fetus, fetal membranes, fetal fluid and/or placentomes). A total of 1736 cows in ten commercial, pasture-based New Zealand dairy herds were examined for pregnancy by transcutaneous ultrasound across the right flank and transrectal ultrasound between 37 and 198 days of gestation. The gold standard was derived from calving records or examination at slaughter. The overall sensitivity of transrectal ultrasound (96.24%) was markedly higher than flank ultrasound (58.55%) and the overall probability of a correct diagnosis of pregnancy status was also significantly higher (p<0.0001). From 155 days of gestation, however, flank ultrasound represented a more accurate method of pregnancy diagnosis and the probability of a correct diagnosis was significantly higher (p<0.0001) after this gestational age. The gestational age of 225 cows from four Spring-calving dairy herds was determined and ultrasound pregnancy test recorded, to determine possible fetal characteristics able to be visualized via transcutaneous ultrasound over the right flank in order to age pregnancy during mid to late gestation. Linear or quadratic equations and curves were formulated from 60 to 198 days of gestation. The fetal characteristics of thoracic diameter, abdominal diameter or umbilical diameter can be used to age pregnancy from 60 days of gestation. Placentome height and length were not significant in the determination of gestational age

Kondo physics in a dissipative environment

We report nonperturbative results for the interacting quantum-critical behavior in a Bose-Fermi Kondo model describing a spin-1/2 coupled both to a fermionic band with a pseudogap density of states and to a dissipative bosonic bath. The model serves as a paradigm for studying the interplay between Kondo physics and low-energy dissipative modes in strongly correlated systems.Comment: 2 pages, 2 figures. Proceedings of The International Conference on Strongly Correlated Electron Systems (SCES'07), accepted for publication in Physica

Young people's beliefs about help-seeking for first episode psychosis

The importance of early intervention for positive outcomes following a first episode of psychosis (FEP) is recognised, however, there are still delays in young people seeking help. The aim of this qualitative study was to explore beliefs about help-seeking in young people who have recently experienced a FEP. Twelve participants were interviewed and transcripts were analysed using grounded theory. Five categories of beliefs were identified which contributed to the development of a preliminary model of beliefs about a need for help-seeking. Young people’s beliefs about their experiences as normal or abnormal, and about the process and outcome of help-seeking, influenced beliefs about needing help. Existing beliefs about mental health problems, and beliefs about the impact of experiences on the self were important to the meaning young people ascribed to beliefs about help-seeking. Social networks were important in the development of these beliefs. The study identified beliefs which promoted and inhibited young people’s help-seeking beliefs for FEP. Self-stigma was present prior to help-seeking. Implications for clinical interventions include education to promote help-seeking for distress and not abnormality, and to dispel myths about the help-seeking process and outcome. Further research is needed to determine which beliefs are most important to young people’s help-seeking for FEP

Magnetic impurities in gapless Fermi systems: perturbation theory

We consider a symmetric Anderson impurity model, with a soft-gap hybridization vanishing at the Fermi level with a power law r > 0. Three facets of the problem are examined. First the non-interacting limit, which despite its simplicity contains much physics relevant to the U > 0 case: it exhibits both strong coupling (SC) states (for r 1), with characteristic signatures in both spectral properties and thermodynamic functions. Second, we establish general conditions upon the interaction self-energy for the occurence of a SC state for U > 0. This leads to a pinning theorem, whereby the modified spectral function is pinned at the Fermi level for any U where a SC state exists; it generalizes to arbitrary r the familiar pinning condition for the normal r = 0 Anderson model. Finally, we consider explicitly spectral functions at the simplest level: second order perturbation theory in U, which we conclude is applicable for r 1 but not for 1/2 < r < 1. Characteristic spectral features observed in numerical renormalization group calculations are thereby recovered, for both SC and LM phases; and for the SC state the modified spectral functions are found to contain a generalized Abrikosov-Suhl resonance exhibiting a characteristic low-energy Kondo scale with increasing interaction strength.Comment: 24 pages, 7 figures, submitted to European Physical Journal

Continuous-Time Monte Carlo study of the pseudogap Bose-Fermi Kondo model

We study the pseudogap Bose-Fermi Anderson model with a continuous-time quantum Monte Carlo (CT-QMC) method. We discuss some delicate aspects of the transformation from this model to the Bose-Fermi Kondo model. We show that the CT-QMC method can be used at sufficiently low temperatures to access the quantum critical properties of these models.Comment: SCES 2010 Proceeding

Magnetic quantum phase transition in an anisotropic Kondo lattice

The quantum phase transition between paramagnetic and antiferromagnetic phases of the Kondo lattice model with Ising anisotropy in the intersite exchange is studied within the framework of extended dynamical mean-field theory. Nonperturbative numerical solutions at zero temperature point to a continuous transition for both two- and three-dimensional magnetism. In the former case, the transition is associated with critical local physics, characterized by a vanishing Kondo scale and by an anomalous exponent in the dynamics close in value to that measured in heavy-fermion CeCu_{5.9}Au_{0.1}.Comment: 4 pages, 3 figures. Version published in Phys. Rev. Let

Numerical renormalization-group study of the Bose-Fermi Kondo model

We extend the numerical renormalization-group method to Bose-Fermi Kondo models (BFKMs), describing a local moment coupled to a conduction band and a dissipative bosonic bath. We apply the method to the Ising-symmetry BFKM with a bosonic bath spectral function $\eta(\omega)\propto \omega^s$, of interest in connection with heavy-fermion criticality. For $0<s<1$, an interacting critical point, characterized by hyperscaling of exponents and $\omega/T$-scaling, describes a quantum phase transition between Kondo-screened and localized phases. Connection is made to other results for the BFKM and the spin-boson model.Comment: 4 pages, 4 figure

Local quantum critical point in the pseudogap Anderson model: finite-T dynamics and omega/T scaling

The pseudogap Anderson impurity model is a paradigm for locally critical quantum phase transitions. Within the framework of the local moment approach we study its finite-T dynamics, as embodied in the single-particle spectrum, in the vicinity of the symmetric quantum critical point (QCP) separating generalized Fermi-liquid (Kondo screened) and local moment phases. The scaling spectra in both phases, and at the QCP itself, are obtained analytically. A key result is that pure omega/T-scaling obtains at the QCP, where the Kondo resonance has just collapsed. The connection between the scaling spectra in either phase and that at the QCP is explored in detail.Comment: 12 pages, 7 figure

Soil deformations caused by soft-ground tunnelling

This thesis discusses the interaction between methods of tunnelling in soil and sources of ground loss. Two distinct phases of settlement in cohesive soils are identified. Short-term settlements are caused by loss of ground into the tunnel and long term settlements are caused by consolidation of the ground around the tunnel. A stochastic model of ground movements caused by volume loss into the tunnel is developed in order to explain in-situ observations. Consolidation settlement is estimated with the aid of flow nets developed by finite difference numerical modelling. These nets are also used to estimate the contribution of seepage to tunnel face instability. Field observations of ground movements caused by tunnelling In soft, cohesive ground were made at three sites. These measurements were taken In order not only to add to the store of case history evidence already available, but also in a direct attempt to confirm or disprove the theoretical model. Tunnelling conditions were different in each case. One tunnel was shield-driven in laminated clay, one was shield-driven with the aid of compressed air support In alluvial organic slit, and one was driven without a shield in stiff, stony clay. These case histories confirm that settlement troughs of Gaussian configuration were developed, agreeing with the stochastic model, and that long-term consolidation may develop in clay soils on the removal of compressed air support from the tunnel

Solid State NMR and Molecular Dynamics studies of solid crystal systems

Solid state systems can often exhibit dynamics on the molecular level, changing conformations, rotating or moving across a crystal structure. In this work, a combination of Nuclear Magnetic Resonance (NMR), Molecular Dynamics (MD) and Markov models are utilised to describe and explain the dynamics seen on solid crystals and pharmaceutical solvates. NMR is used first to gain an idea of the dynamics, with relaxation rates used to measure activation energies and motional models suggested to fit the data. MD simulations are performed to directly simulate the motion, with the extraction of copies of each molecule from each simulation allowing motion on timescales greater than the simulation time to be observed. The simulations are analysed utilising Markov modelling, assigning conformations to states, extracting state samples to determine the metastable conformations and calculating transition times between these states. Several of the lower diamondoids are analysed, providing descriptions of the motion and agreeing with previously suggested models of the dynamics. These also show some of the technical considerations that need to be taken into account when analysing systems using relatively short simulations. However, good agreement with experiment can still be achieved with these methods with careful planning. Two pharmaceutical solvates are also investigated, allowing a picture of the rapid solvent motion to be obtained. These pictures give some interesting avenues for further investigation, as well as showing this method can be applied to different solid systems