Designing ICT systems in the developing world is perceived to be a challenge. But is this really a challenge if we use state-of-the-art development methods? Will the fact that most standards and heuristics are made in the western world render them useless as tools of making modern computer software for the underdeveloped world? In this thesis I will analyze the findings of a software development project I did for my employer, National Center for Fetal Medicine (NCFM) at St. Olav’s Hospital in Trondheim, Norway. In this project we used a user centered development process as defined in ISO 9142-210 to make and test the prototype of an ultrasound help system. We tested the system using two different user groups: midwives in KwaZulu-Natal participating in an ultrasound teaching and training program held by NCFM and midwives in Trondheim, Norway, receiving a post-qualification course in ultrasound diagnostics also held by NCFM at the Norwegian University of Science and Technology (NTNU) in Trondheim. I will analyze the test results and then do an evaluation of the methods used – both the user-centered design process and the usability methods to see if the methods have worked in my project.

The propagation mechanism of signals for multiple input multiple output (MIMO) channels can be explained via a random matrix. Random matrix theory is a very powerful tool to understand behaviour of such channels and analyse their performance measure of MIMO systems. In this work we study: The asymptotic eigenvalue distribution and the mutual information of a multiuser (MU) multiple-input multiple output (MIMO) channel with a certain fraction of users experiencing line-of-sight. It shows that the AED of the channel matrix decomposes into two separate bulks for practically relevant parameter choices and differs very much from the common assumption of independent identically distributed (iid) entries which induces the quarter circle law. This happens even without antenna correlation at either side of the channel. In order to tackle this problem the paper makes use of recent developments in free probability theory which allow to deal with complex-valued eigenvalue distributions of non-Hermitian matrices. Moreover to understand behaviour of MIMO channels we derived asymptotic complex-valued eigenvalue distributions of practically relevant channels models by means of their respective square equivalent and singular equivalent of channel matrices. Finally we derived an explicit mutual information formula which allows us calculate the mutual information (in general) analytically in high signal-to noiseratio (SNR) regime for numerous practical important scenarios. Furthermore the numerical result shows that, high-SNR approximation draws reliable portrait even for quite moderate SNR level.

Reverberation is defined as equally-spaced, bright linear echoes resulting from reflection from specular-type interfaces. They are provoked by the acoustic Impedance change between the tissue and transducer front surface. B. Angelsen developed a mathematical approach to correct this ultrasound artifact by coupling the ultrasound transducer with an ideal electrical load in order to obtain zero reflection coefficients on the transducer from face [1]. However, when analyzing Impedance spectroscopy this approach cannot be achieved by using passive electronics in most simulated cases. Active impedance may be seen as a trend to improve image quality. This research therefore implements and simulates methods for active impedance synthesis [5] and applies Particle Swarm Optimization to the proposed electronics. Finally, the simulations are compared through a LAB experiment.

The commonly used simulation method Field II, which is based on the spatial impulse response approach, has excellent accuracy in linear domain. However the computational time can be up to many days for one simulation. One of the solutions to this problem is a convolution-based methodology called COLE. It is much faster than Field II and has very good approximation. It generates the data by reducing multi-dimensional convolution model to multiple single-dimensional convolutions. This thesis is about implementing COLE on the FieldSim 3 platform and using it for blood flow imaging. This platform is written in MATLAB with object-oriented programming and it is now under development at department of circulation and medical imaging. Both Field II and real scanner have been used to compare with COLE. The simulated phantom for both simulators was a straight tube with scatterers moving inside, whereas a string phantom was used to get the data from the scanner. The computational time of COLE with 2D Doppler mode scan in FieldSim 3 achieved 85 times faster than Field II. The plotted PW Doppler spectra and the 2D power spectra showed that the velocity resolutions of both simulators were at the same level. COLE had higher noise floor than Field II and scanner in Doppler mode scan. COLE had relatively high sampling frequency requirement compared with Field II. If the sampling frequency was not high enough, COLE would produce side lobes in the PW Doppler spectra.

Understanding intracellular processing of gene vectors will help to improve vector design in gene therapy. Chitosan nanoparticles have been previously identied as safe and non toxic gene vector. Linear chitosan oligomer (LCO) and self branched trisaccharide chitosan oligomer (SBTCO) have been shown to be able to pack DNA, balancing betweencomplexation and intracellular unpacking . However, the transfection ecacies of thesetwo chitosans diers considerably with the level of transgene expression higher for SBTCOcompared to LCO. SBTCO have been recently reported to be taken up solely by caveolaemediated endocytosis (CvME) while LCO uses both clathrin mediated endocytosis (CME)and CvME.In the present study, the CvME was studied. An immunostaining protocol for detectionof caveolin (cav) was established. Polyplexes of SBTCO seemed to trigger the formationof more caveosomes than did LCO polyplexes. SBTCO polyplexes were more localisedin the caveosome than LCO polyplexes at 3 hours incubation period. These ndingssuggested that SBTCO polyplexes delivers more DNA into the cell than LCO polyplexesand that SBTCO polyplexes are processed intracellularly solely via the CvME pathway.Likewise, it suggested LCO polyplexes have preferred intracellular processing pathwaywhich is not CvME. Collectively, these results demonstrated that SBTCO is protectedfrom the degradative endosome and might therefore be an ecient and good tool to delivertherapeutic DNA.

The presence of hypoxia in tumors has been related to poor prognosis and low overall survival. In particular, cyclic hypoxia has been related to higher metastatic potential. Hence, it is important to study the mechanisms involved in the response of tumors when these experience cyclic hypoxia. In this work A-07-GFP human melanoma xenografts with dorsal window chambers were used as a model to study the effects of exposure to cyclic hypoxia on tumor growth and on the morphology and function of the tumor vascular networks. First-pass imaging of a fluorescent tracer was used to study the function of tumor vasculature, and tumor vascular morphology was assessed by producing vascular masks from high-resolution images. Vascular morphology was described by quantification of vascular length density, vascular area fraction, interstitial distance and vessel diameter. The function of the tumor vasculature was assessed by quantification of the blood supply times (BSTs). It was found that exposure to cyclic hypoxia resulted in higher vascular densities, a trend towards higher BST values and decreased growth rate in the tumors. The results could be associated with enhanced angiogenesis in the tumors that received the cyclic hypoxia treatment due to overexpression of pro-angiogenic genes regulated by HIF-1α.