The epidemiology of avian influenza in the Mekong River Delta of Viet Nam : a dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University

Between December 2003 and December 2012 a total of 4,349 commune-level outbreaks of highly pathogenic avian influenza (HPAI) H5N1 were recorded in domestic poultry flocks throughout Viet Nam. Throughout the same period there were 123 cases of HPAI H5N1 virus infection in humans, 61 of which were fatal. The studies presented in this thesis are largely based on data collected from a prospective cohort study of domestic poultry in 157 flocks in the Mekong River Delta of Viet Nam between December 2008 and April 2010. The first research chapter (Chapter 3) provides a description of the components and design features of an animal health decision support system for use in Viet Nam. While not explicitly used for the prospective cohort study, the motivation for development of this system was to provide a means for recording and storing animal health data so as to minimise duplication of data collection efforts. A feature of the system is the inclusion of a flexible reporting tool that provides system users with the capability of developing reports to deal with virtually any animal health issue, not just avian influenza. The intent of this system is that it will allow the Vietnamese Department of Animal Health to identify and respond to existing and emerging threats to animal health in a timely and cost-effective manner. Our descriptive analyses (Chapter 4) show that the overall incidence rate of influenza Type A and H5 virus infection in village poultry was relatively high throughout the 17-month follow up period of the prospective cohort study. This implies that interventions such as vaccination, movement controls and biosecurity measures need to be carried out continuously throughout the year rather than focusing only on the established high risk periods. Broiler ducks had an incidence rate of influenza H5 virus infection that was approximately four times greater than that of layer ducks and in-contact species. This indicates that broiler ducks should be the focus of disease surveillance and control strategies. Survival analyses, accounting for the intermittent sampling of birds throughout the follow-up period of the prospective cohort study (by interval censoring) and for the hierarchical structure of the data set were used to determine the duration of immunity to H5N1 following vaccination (Chapter 5). After adjusting for the effect of known confounders and unmeasured variation at the flock level the duration of immunity to H5N1 following vaccination was estimated to be in the order of 56 (95% CI 51 – 61) days, considerably shorter than the duration of immunity previously reported in laboratory-based studies. A multilevel logistic regression analysis carried out to identify risk factors for influenza Type A virus infection in the prospective cohort study poultry population found that the relative contribution of unmeasured flock- and bird-level factors on influenza Type A virus infection risk were approximately equal (Chapter 6). Most of the significant fixed-effects were flock-level exposures indicating that interventions to reduce the maintenance and transmission of influenza Type A virus in domestic poultry in this area of Viet Nam should be applied at the individual bird and individual flock level. Chapter 7 presents the results of a study of poultry movement events that occurred in the south of Viet Nam between September 2009 and June 2010. Poultry were more likely to be moved between communes with provincial roads and between communes with more than 1,000 poultryowning households. Assuming a causal relationship exists between a commune-to-commune poultry movement activity and HPAI H5N1 risk, a conclusion from this study was that communes more likely to be connected to others as a result of movement should be targeted for disease control and surveillance. The findings presented in each of these chapters of this thesis have broadened our knowledge of the epidemiology of not only the HPAI H5N1 subtype, but influenza Type A viruses in poultry in general. It should be stressed that the methodological techniques that have been used in this thesis can be applied to a wide range of animal health issues, not just HPAI H5N1

Outage performance analysis of non-orthogonal multiple access with time-switching energy harvesting

In recent years, although non-orthogonal multiple access (NOMA) has shown its potentials thanks to its ability to enhance the performance of future wireless communication networks, a number of issues emerge related to the improvement of NOMA systems. In this work, we consider a half-duplex (HD) relaying cooperative NOMA network using decode-and-forward (DF) transmission mode with energy harvesting (Ell) capacity, where we assume the NOMA destination (D) is able to receive two data symbols in two continuous time slots which leads to the higher transmission rate than traditional relaying networks. To analyse EH, we deploy time-switching (TS) architecture to comprehensively study the optimal transmission time and outage performance at D. In particular, we are going to obtain closed-form expressions for outage probability (OP) with optimal TS ratio for both data symbols with both exact and approximate forms. The given simulation results show that the placement of the relay (R) plays an important role in the system performance.Web of Science253918

Relativistic Hartree-Fock theory. Part I: density-dependent effective Lagrangians

Effective Lagrangians suitable for a relativistic Hartree-Fock description of nuclear systems are presented. They include the 4 effective mesons $\sigma, \omega, \rho$ and $\pi$ with density-dependent meson-nucleon couplings. The criteria for determining the model parameters are the reproduction of the binding energies in a number of selected nuclei, and the bulk properties of nuclear matter (saturation point, compression modulus, symmetry energy). An excellent description of nuclear binding energies and radii is achieved for a range of nuclei encompassing light and heavy systems. The predictions of the present approach compare favorably with those of existing relativistic mean field models, with the advantage of incorporating the effects of pion-nucleon coupling.Comment: 26 pages, 5 table

On a nonlinear heat equation associated with Dirichlet -- Robin conditions

This paper is devoted to the study of a nonlinear heat equation associated with Dirichlet-Robin conditions. At first, we use the Faedo -- Galerkin and the compactness method to prove existence and uniqueness results. Next, we consider the properties of solutions. We obtain that if the initial condition is bounded then so is the solution and we also get asymptotic behavior of solutions as. Finally, we give numerical resultsComment: 20 page

Shell Structure and ρ\rho-Tensor Correlations in Density-Dependent Relativistic Hartree-Fock theory

A new effective interaction PKA1 with $\rho$-tensor couplings for the density-dependent relativistic Hartree-Fock (DDRHF) theory is presented. It is obtained by fitting selected empirical ground state and shell structure properties. It provides satisfactory descriptions of nuclear matter and the ground state properties of finite nuclei at the same quantitative level as recent DDRHF and RMF models. Significant improvement on the single-particle spectra is also found due to the inclusion of $\rho$-tensor couplings. As a result, PKA1 cures a common disease of the existing DDRHF and RMF Lagrangians, namely the artificial shells at 58 and 92, and recovers the realistic sub-shell closure at 64. Moreover, the proper spin-orbit splittings and well-conserved pseudo-spin symmetry are obtained with the new effective interaction PKA1. Due to the extra binding introduced by the $\rho$-tensor correlations, the balance between the nuclear attractions and the repulsions is changed and this constitutes the physical reason for the improvement of the nuclear shell structure.Comment: 20 pages, 11 figures, 6 table

Pairing phase transition: A Finite-Temperature Relativistic Hartree-Fock-Bogoliubov study

Background: The relativistic Hartree-Fock-Bogoliubov (RHFB) theory has recently been developed and it provides a unified and highly predictive description of both nuclear mean field and pairing correlations. Ground state properties of finite nuclei can accurately be reproduced without neglecting exchange (Fock) contributions. Purpose: Finite-temperature RHFB (FT-RHFB) theory has not yet been developed, leaving yet unknown its predictions for phase transitions and thermal excitations in both stable and weakly bound nuclei. Method: FT-RHFB equations are solved in a Dirac Woods-Saxon (DWS) basis considering two kinds of pairing interactions: finite or zero range. Such a model is appropriate for describing stable as well as loosely bound nuclei since the basis states have correct asymptotic behaviour for large spatial distributions. Results: Systematic FT-RH(F)B calculations are performed for several semi-magic isotopic/isotonic chains comparing the predictions of a large number of Lagrangians, among which are PKA1, PKO1 and DD-ME2. It is found that the critical temperature for a pairing transition generally follows the rule $T_c = 0.60\Delta(0)$ for a finite-range pairing force and $T_c = 0.57\Delta(0)$ for a contact pairing force, where $\Delta(0)$ is the pairing gap at zero temperature. Two types of pairing persistence are analysed: type I pairing persistence occurs in closed subshell nuclei while type II pairing persistence can occur in loosely bound nuclei strongly coupled to the continuum states. Conclusions: This first FT-RHFB calculation shows very interesting features of the pairing correlations at finite temperature and in finite systems such as pairing re-entrance and pairing persistence.Comment: 13 pages, 11 figures, accepted version in Phys. Rev.

PSYCHO-PHYSIOLOGICAL CHARACTERISTICS OF MIDDLE-DISTANCE RUNNERS AGED 15-16

The scope of the article is determining the psycho-physiological characteristics of middle-distance runners aged 15-16 which play an important role in providing scientific information for the use of exercise volume and intensity. So as to align with the goals and content of the training in order to improve the athlete's athletic performance, and at the same time, overcome difficulties to achieve the goal in specialized endurance education. Identifying psychological and physiological characteristics of middle-distance athletes at the ages of 15-16 plays an important role in providing scientific information for the use of the amount of movement, intensity, and break to suit the objectives and contents of training to improve the athletic performance of athletes. At the same time, difficulties are overcome to achieve the purpose of educating professional endurance.  Article visualizations

Superheavy magic structures in the relativistic Hartree-Fock-Bogoliubov approach

We have explored the occurrence of the spherical shell closures for superheavy nuclei in the framework of the relativistic Hartree-Fock-Bogoliubov (RHFB) theory. Shell effects are characterized in terms of two-nucleon gaps $\delta_{2n(p)}$. Although the results depend slightly on the effective Lagrangians used, the general set of magic numbers beyond $^{208}$Pb are predicted to be $Z = 120$, $138$ for protons and $N = 172$, 184, 228 and 258 for neutrons, respectively. Specifically the RHFB calculations favor the nuclide $^{304}$120 as the next spherical doubly magic one beyond $^{208}$Pb. Shell effects are sensitive to various terms of the mean-field, such as the spin-orbit coupling, the scalar and effective masses.Comment: 3 figures, 1 table, and 5 page

Magicity of neutron-rich isotopes within relativistic self-consistent approaches

The formation of new shell gaps in intermediate mass neutron-rich nuclei is investigated within the relativistic Hartree-Fock-Bogoliubov theory, and the role of the Lorentz pseudo-vector and tensor interactions is analyzed. Based on the Foldy-Wouthuysen transformation, we discuss in detail the role played by the different terms of the Lorentz pseudo-vector and tensor interactions in the appearing of the $N=16$, 32 and 34 shell gaps. The nuclei $^{24}$O, $^{48}$Si and $^{52,54}$Ca are predicted with a large shell gap and zero ($^{24}$O, $^{52}$Ca) or almost zero ($^{48}$Si, $^{54}$Ca) pairing gap, making them candidates for new magic numbers in exotic nuclei. We find from our analysis that the Lorentz pseudo-vector and tensor interactions induce very specific evolutions of single-particle energies, which could clearly sign their presence and reveal the need for relativistic approaches with exchange interactions.Comment: 7 pages, 5 figures, 1 tabl