MULTI-ANTENNA FIXED POSITION SYSTEM FOR LESION DETECTION WITHIN PHANTOMS

This project advances the current capability of using Ultra High Frequency (UHF) antennas to detect dielectric differences within a phantom, as a prerequisite for bone fracture analysis. The following research was conducted to investigate whether the scatter parameter measurements from multiple fixed position antennas could successfully reconstruct images of a phantom with a lesion. An Ultra-WideBand (UWB) Antipodal Vivaldi Antenna (AVA) was designed to transmit frequencies between 1800MHz and 2500MHz with an end fire beam between ϕ= ±4° (confirming the main beam is directed towards the phantom). Simulations and measurements were performed using four antennas, eight antennas and sixteens antennas spaced equally within the system. For each system, three contrasting phantom scenarios were taken, a homogenous phantom, a phantom with the lesion placed at 0°, and then with the lesion placed at 90°. The reconstructed images were analysed, comparing the three tests, and showed that using a sixteen-element system, the lesion position but not size was clearly detectable. These findings confirm that a fixed position system can be used as an alternative to the current process, which then drastically reduces testing times

Multi-antenna fixed position system for lesion detection within phantoms

This project advances the current capability of using Ultra High Frequency (UHF) antennas to detect dielectric differences within a phantom, as a prerequisite for bone fracture analysis. The following research was conducted to investigate whether the scatter parameter measurements from multiple fixed position antennas could successfully reconstruct images of a phantom with a lesion. An Ultra-WideBand (UWB) Antipodal Vivaldi Antenna (AVA) was designed to transmit frequencies between 1800MHz and 2500MHz with an end fire beam between φ= ±4° (confirming the main beam is directed towards the phantom). Simulations and measurements were performed using four antennas, eight antennas and sixteens antennas spaced equally within the system. For each system, three contrasting phantom scenarios were taken, a homogenous phantom, a phantom with the lesion placed at 0°, and then with the lesion placed at 90°. The reconstructed images were analysed, comparing the three tests, and showed that using a sixteen-element system, the lesion position but not size was clearly detectable. These findings confirm that a fixed position system can be used as an alternative to the current process, which then drastically reduces testing times

Chiral Green's Functions in Superconformal Field Theory

By solving the Ward identities in a superconformal field theory we find the unique three-point Green's functions composed of chiral superfields for N = 1,2,3,4 supersymmetry. We show that the N=1 four-point function with R-charge equal to one is uniquely determined by the Ward identities up to the specification of four constants. We discuss why chiral Green's functions above three-points, with total R-charge greater than N, are not uniquely determined.Comment: 32 pages, no figures, LaTeX2e forma

Diversity and structure of human T-Cell receptor β-chain variable region genes

The nucleotide sequences of 27 T-cell receptor β cDNA clones isolated from a human peripheral lymphocyte library were determined and compared to five additional published sequences. These cDNA clones represent 22 distinct T-cell receptor β-chain variable region (Vβ) gene segment sequences, which fall into 15 different Vβ gene subfamilies, each containing six or fewer members. From this analysis, we estimate that the repertoire of expressed human Vβ genes is <59, apparently much smaller than the immunoglobulin heavy chain and light chain variable region (VH and VL) repertoires. Variability plots comparing these human Vβ regions with each other and with published mouse Vβ regions provide evidence for only four hypervariable regions homologous to those seen in comparisons of immunoglobulin V regions. Somatic hypermutation appears to be used infrequently, if at all, in these Vβ genes

A note on the Painleve analysis of a (2+1) dimensional Camassa-Holm equation

We investigate the Painleve analysis for a (2+1) dimensional Camassa-Holm equation. Our results show that it admits only weak Painleve expansions. This then confirms the limitations of the Painleve test as a test for complete integrability when applied to non-semilinear partial differential equations.Comment: Chaos, Solitons and Fractals (Accepted for publication

Biochemical diagnosis of ventricular dysfunction in elderly patients in general practice: observational study

Objective: To investigate the usefulness of measuring plasma concentrations of B type natriuretic peptide in the diagnosis of left ventricular systolic dysfunction in an unselected group of elderly people. Design: Observational study. Setting: General practice with four centres in Poole, Dorset. Participants: 155 elderly patients aged 70 to 84 years. Main outcome measures: Diagnostic characteristics of plasma B type natriuretic peptide measured by radioimmunoassay as a test for left ventricular systolic dysfunction assessed by echocardiography. Results: The median plasma concentration of B type natriuretic peptide was 39.3 pmol/l in patients with left ventricular systolic dysfunction and 15.8 pmol/l in those with normal function. The proportional area under the receiver operator curve was 0.85. At a cut-off point of 18.7 pmol/l the test sensitivity was 92% and the predictive value 18%. Conclusions: Plasma concentration of B type natriuretic peptide could be used effectively as an initial test in a community screening programme and, possibly, using a low cut-off point, as a means of ruling out left ventricular systolic dysfunction. It is, however, not a good test to “rule in” the diagnosis, and access to echocardiography remains essential for general practitioners to diagnose heart failure early