Aerodynamic spike nozzle Patent

Constructing fluid spike nozzle to eliminate heat transfer and high temperature problems inherent in physical spike

Electron trapping effects in cadmium sulphide

This work is an attempt to determine the origin and. behaviour of the defect centres in the forbidden gap of cadmium sulphide. The methods of measurement used were thermally stimulated current and infra-red luminescence techniques. After introductory chapters on semiconductor theory and the material, cadmium sulphide, the published results on T.S.C. and infra-red luminescence measurements are surveyed and analysed. Results are then given for a series of samples with varying degrees of sulphur doping. During the work, the need for a more accurate method of T.S.C. curve analysis arose, and the curve fitting technique was developed for this purpose. It was found to have many advantages over existing techniques. The combination of T.S.C. and infra-red techniques led to the identification of the centres involved in the infrared luminescence. Important traps at O.48, 0.62 and O.84 eV below the conduction band are identified, and their photochemical reactions with the luminescent centres described. It is shown that the luminescent centres are identical with the sensitising centres

The quest for a donor: probability based methods offer help

When a patient in need of a stem cell transplant has no compatible donor within his or her closest family, and no matched unrelated donor can be found, a remaining option is to search within the patient’s extended family. This situation often arises when the patient is of an ethnic minority, originating from a country that lacks a well-developed stem cell donor program, and has HLA haplotypes that are rare in his or her country of residence. Searching within the extended family may be time-consuming and expensive, and tools to calculate the probability of a match within groups of untested relatives would facilitate the search. We present a general approach to calculating the probability of a match in a given relative, or group of relatives, based on the pedigree, and on knowledge of the genotypes of some of the individuals. The method extends previous approaches by allowing the pedigrees to be consanguineous and arbitrarily complex, with deviations from Hardy-Weinberg equilibrium. We show how this extension has a considerable effect on results, in particular for rare haplotypes. The methods are exemplified using freeware programs to solve a case of practical importance

Estimation of Parameters in DNA Mixture Analysis

In Cowell et al. (2007), a Bayesian network for analysis of mixed traces of DNA was presented using gamma distributions for modelling peak sizes in the electropherogram. It was demonstrated that the analysis was sensitive to the choice of a variance factor and hence this should be adapted to any new trace analysed. In the present paper we discuss how the variance parameter can be estimated by maximum likelihood to achieve this. The unknown proportions of DNA from each contributor can similarly be estimated by maximum likelihood jointly with the variance parameter. Furthermore we discuss how to incorporate prior knowledge about the parameters in a Bayesian analysis. The proposed estimation methods are illustrated through a few examples of applications for calculating evidential value in casework and for mixture deconvolution

In-situ Measurement of Transducer Impedance using AFE Active Termination through Analysis of Ultrasound Echoes

Measurement of transducer impedance in ultrasound systems indicates both the performance of a transducer and the presence of damaged elements and cables. Load impedance analysis is typically performed with dedicated test equipment and is a time consuming and thus expensive process, especially for high channel count systems. This paper proposes a method for the measurement of channel source impedance (transducer, coaxial cable and T/R switch) through the use of an integrated receiver analogue front end with configurable termination resistance. The proposed method is first demonstrated using a pitch-catch configuration using a separate source transducer to excite the transducer under test. Subsequently the method is demonstrated the Ultrasound Array Research Platform (UARP) and a linear array transducer in a pulse echo mode where the transducer impedance is determined through the analysis of two ultrasound echoes. The proposed method is especially suited to rapid transducer testing in the field, such as in a hospital, or where access to the transducer is not possible as in many industrial processes

Analysis of forensic DNA mixtures with artefacts

DNA is now routinely used in criminal investigations and court cases, although DNA samples taken at crime scenes are of varying quality and therefore present challenging problems for their interpretation. We present a statistical model for the quantitative peak information obtained from an electropherogram of a forensic DNA sample and illustrate its potential use for the analysis of criminal cases. In contrast with most previously used methods, we directly model the peak height information and incorporate important artefacts that are associated with the production of the electropherogram. Our model has a number of unknown parameters, and we show that these can be estimated by the method of maximum likelihood in the presence of multiple unknown individuals contributing to the sample, and their approximate standard errors calculated; the computations exploit a Bayesian network representation of the model. A case example from a UK trial, as reported in the literature, is used to illustrate the efficacy and use of the model, both in finding likelihood ratios to quantify the strength of evidence, and in the deconvolution of mixtures for finding likely profiles of the individuals contributing to the sample. Our model is readily extended to simultaneous analysis of more than one mixture as illustrated in a case example. We show that the combination of evidence from several samples may give an evidential strength which is close to that of a single-source trace and thus modelling of peak height information provides a potentially very efficient mixture analysis

Elevation resolution enhancement in 3D photoacoustic imaging using FDMAS beamforming

Photoacoustic imaging is a non-invasive and non-ionizing imaging technique that combines the spectral selectivity of laser excitation with the high resolution of ultrasound imaging. It is possible to identity the vascular structure of the cancerous tissue using this imaging modality. However, elevation and lateral resolution of photoacoustic imaging is usually poor for imaging target. In this study, three dimension filter delay multiply and sum beamforming technique (FDMAS(3D)) is used to improve the resolution and enhance the signal to noise ratio (SNR) of the 3D photoacoustic image that is created by using linear array transducer. This beamforming technique showed improvement in the elevation by 36% when its compared with three dimension delay and sum beamforming technique (DAS(3D)). In addition, it enhanced the SNR by 13 dB compared with DAS (3D)

Fort Lawton

"Fort Lawton is the most beatiful infantry post in the United States and also has a health record that is unsurpassed by most military posts in this country.

Acoustic microbubble trapping in blood mimicking fluid

Microbubble (MB) volumetric pulsations can be selectively seeded with external ultrasonic fields. The therapeutic use of this phenomenon encompass mechanical thrombolysis and targeted drug deliveries through sonoporating endothelial cells. However, expected outcomes are still plagued by low bubble concentrations and short circulation time after administration. MBs preferentially flow along the centerline of large vessels which deteriorates biological targeting methodology in the case of vascular disease treatment with MBs. Simultaneous MB imaging and trapping against high flow rates has been recently proposed by instantaneously switching optimized ultrasonic beams. Principles were previously validated by circulating MBs with purified water through a flow phantom. But differences between blood and water call for preliminary investigations with blood mimicking fluid (BMF). This study demonstrated the capability of trapping bubbles in BMF with the acoustic trap but with nearly 40% efficiency reduction over the control in water, being present by the suppressed increase of image brightness