1,053 research outputs found
On the initial-value problem of the Maxwell-Lorentz equations.
We consider the Maxwell-Lorentz equations, i.e., the equation of motion of a charged dust coupled to Maxwell's equations, on an arbitrary general-relativistic spacetime. We decompose this system of equations into evolution equations and constraints, and we demonstrate that the evolution equations are strongly hyperbolic. This result guarantees that the initial-value problem of the Maxwell- Lorentz equations is well-posed. We illustrate this general result with a discussion of spherically symmetric solutions on Minkowski spacetime
A Study of Fatal Cases of Group B Meningococcal Disease Using Non-culture Multilocus Sequence Typing and porA Sequence Typing
Since the introduction of the UK MenC vaccine programme in November 1999 there has been a 97% decrease in the number of confirmed group C meningococcal disease cases. However, in the year of introduction and the subsequent two years an increase in the numbers of group B cases was noted.
Meningococcal infection may be microbiologically confirmed by culture and non culture methods. The introduction by the Meningococcal Reference Unit (MRU) of diagnostic polymerase chain reaction (PCR) testing in 1996 dramatically increased the number of cases ascertained solely by PCR, currently over 50%. Routinely cases determined by PCR only are confirmed to serogroup level and are not characterised further.
This study was carried out to investigate whether the application of non culture DNA sequence typing which had recently been developed by the Heath Protection Agency could improve surveillance of meningococcal disease, and to determine if the increase in the number of observed group B cases was associated with particular meningococcal clones.
The non culture DNA sequence typing of the porA antigen gene and of the seven genes of the Multilocus sequence typing (MLST) scheme was undertaken. Archived samples from one year before and two years following the immunisation programme, 96 samples in total, were analyzed using nested amplification and DNA sequence typing. The non culture group B fatal case data were also compared to other available molecular typing datasets.
Results showed that there was no significant change in predominating group B clones and therefore no significant epidemiological shift in the meningococci causing group B disease, including fatalities, in the years 1999-2001. It was found by the combination of culture and non culture data that the two predominating clonal complexes causing fatal disease were ST41/44 lineage3 (36.3% pre and 30.8% post immunisation) and ST269 (22.4% pre and 31.9% post immunisation). This provided reassurance that the epidemiology of group B meningococcal disease was not impacted by the group C immunisation programme, and in particular that there was no noted proliferation of the hyper invasive ST11 clonal complex among group B disease (there were no fatal ST11 group B cases pre and 4.4% post immunisation). The porA and MLST data is important for group B vaccine development, which is informed by the monitoring of population shift among group B meningococci.
In addition the non culture sequence typing methods described here have subsequently been applied to case cluster and outbreak investigation by the MRU. Incidents involving patients diagnosed by both non culture and culture methods are now able to be resolved
An exploration of the effects of radiation reaction on waves propagating through a warm plasma
Integration of a Cognitive Assessment Task into Exergame Gameplay Elements
Lack of exercise is related to a variety of health issues, including cognitive decline in older adults. Tools for encouraging regular exercise such as exergames are a useful preventative measure, but regular screening for impairment is still important. However, standard cognitive screening methods can be both time-consuming and tedious. Integrating these screening methods into a frequently played exergame is one way to enable regular screening, but requires that the integration is not obtrusive and does not interfere with the gameplay. We present an exergame in which a standard cognitive screening tool, the AX-Continuous Performance Task, is integrated into the game in a non-obstrusive fashion. As an starting step in assessing this approach, we validate the comparability of the measurement capacity of this integrated tool by assessing user performance in the test with non-impaired adults. Our results indicate that the test is comparable to the traditional form of the test when conducted within the context of a game, and is not clearly perceived as a test rather than a gameplay element by the users. However, increasing task complexity through additional gameplay elements does interfere with task performance
Customer equity management : the impact of strategy drivers and customer data management on customer equity outcomes
This research contributes to the field of customer equity by examining how important the strategy drivers of consumption and customer data management are in contributing to the value of the customer asset. A mixed methods approach focused on one sector: the Australian accommodation hotels. From this research, a deeper understanding of how to theorise, conceptualise and practice customer equity management has been achieved
Implications of the UN Sustainable Development Goals for the world's forests
The advent of the United Nations Sustainable Development Goals (SDGs) provided a framework that explicitly embedded the conservation of natural ecosystems among other development objectives. Fundamental to the SDGs is the notion that interactions can occur between their constituent goals and targets in the form of synergies and trade-offs, and that, wherever possible, the former should be promoted and the latter mitigated. Using the conservation of forests (relevant to several SDG targets) as a case study, this thesis seeks to better understand how progress in non-environmental aspects of the development agenda could facilitate or hinder this cause. Through a systematic review, I identify 63 SDG targets associated with potentially beneficial, damaging or mixed impacts on forests, and highlight how potentially damaging targets are often better researched and understood. Using open access data for 122 countries, I explore the empirical relationships between achievement of the SDGs and changes in net forest cover between 2017 and 2020. These analyses suggest that higher achievements in goals on health, education, energy, economy and industry are associated with lower net forest loss, while the processes of improving in goals on economy and climate change mitigation are associated with higher net forest loss. I present a novel framework that combines document analysis and indicator data for 24 SDG targets, to assess the possible implications of a country’s anticipated development trajectory for forests. Applying this to framework to 48 tropical countries, I highlight key areas of each country’s national development agenda that should be monitored or prioritised in order to avoid risks, seize opportunities, and provide enabling conditions for effective forest conservation. The thesis concludes with a summary of the major findings, a discussion the novel contributions and limitations of the work, and suggestions for further work that could help progress the topic further
Software Tools to Support Research on Airport Departure Planning
A simple, portable and useful collection of software tools has been developed for the analysis of airport surface traffic. The tools are based on a flexible and robust traffic-flow model, and include calibration, validation and simulation functionality for this model. Several different interfaces have been developed to help promote usage of these tools, including a portable Matlab‘ implementation of the basic algorithms; a web-based interface which provides online access to automated analyses of airport traffic based on a database of real-world operations data which covers over 250 U.S. airports over a 5-year period; and an interactive simulation-based tool currently in use as part of a college-level educational module. More advanced applications for airport departure traffic include taxi-time prediction and evaluation of “windowing” congestion control
Observation of Parity Nonconservation in Møller Scattering
We report a measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A_(PV) = [-175 ± 30(stat)± 20(syst)] X 10^(-9). This first direct observation of parity nonconservation in Møller scattering leads to a measurement of the electron’s weak charge at low energy Q^e_W = -0:053 ± 0:011. This is consistent with the standard model expectation at the current level of precision: sin^2θ_W = (M_Z)_(MS) = 0:2293 ± 0:0024(stat) ± 0:0016(syst) ± 0:0006(theory)
Synthesis, X-ray structural characterization, and DFT calculations of binuclear mixed-ligand copper(II) complexes containing diamine, acetate and methacrylate ligands
The dinuclear Cu(II) complexes [Cu(en)(MAA)(µ-CH3COO)]2 (1) and [Cu(pn)(MAA)(µ-CH3COO)]2 (2) where MAA, en and pn are methacrylate, ethylendiamine and 1,3-propylendiamine, respectively, have been synthesized and characterized by elemental analysis, FT-IR and UV-Vis spectroscopy. The structures of the complexes have been determined by single-crystal X-ray diffraction analyses. In the dinuclear complexes 1 and 2 the two copper centers are five-coordinated and exhibit distorted square pyramidal geometries. The theoretical geometries of the studied compounds have been calculated by means of density functional theory (DFT) at the B3LYP/6-311+G(d,p)/LanL2DZ level considering effective core potential (ECP)
Synthesis, X-ray Structural Characterization, and DFT Calculations of Mononuclear Nickel(II) Complexes Containing Diamine and Methacrylate Ligands
The mononuclear Ni(II) complexes [Ni(en)2(H2O)2](MAA)2 (1) and [Ni(pn)2(MAA)2] (2), where MAA, en and pn are
methacrylate, ethylendiamine and 1,3-propylendiamine, respectively, have been synthesized and characterized by elemental
analysis, FT-IR and UV–Vis spectroskopy. Structures of the complexes have been determined by single-crystal
X-ray diffraction analyses. In the nickel(II) complexes 1 and 2 nickel(II) ion is six-coordinate and has a distorted octahedral
geometry. Ni(II) is bonded to four nitrogen atoms of the two diamines and additionally to two oxygen atoms of aqua
ligand in 1, and two oxygen atoms of methacrylate ligands in 2. The theoretical geometries of the studied compounds
have been calculated by means of density functional theory (DFT) at the B3LYP/6-311+G(d,p)/LanL2DZ level and considering
effective core potential (ECP). The comparison of the results indicates that the employed DFT method yields
good agreement with experimental data
- …