Full tomographic reconstruction of 2D vector fields using discrete integral data

Vector field tomography is a field that has received considerable attention in recent decades. It deals with the problem of the determination of a vector field from non-invasive integral data. These data are modelled by the vectorial Radon transform. Previous attempts at solving this reconstruction problem showed that tomographic data alone are insufficient for determining a 2D band-limited vector field completely and uniquely. This paper describes a method that allows one to recover both components of a 2D vector field based only on integral data, by solving a system of linear equations. We carry out the analysis in the digital domain and we take advantage of the redundancy in the projection data, since these may be viewed as weighted sums of the local vector field's Cartesian components. The potential of the introduced method is demonstrated by presenting examples of vector field reconstruction

A national register for surveillance of inherited disorders: beta thalassaemia in the United Kingdom

OBJECTIVE: To demonstrate the value of a national register for surveillance of services for an inherited disorder. METHODS: Data from the United Kingdom Thalassaemia Register and the United Kingdom Register of Prenatal Diagnosis for Haemoglobin Disorders were combined in a database; these registers include all fetuses known to have been diagnosed with beta thalassaemia major, beta thalassaemia intermedia, or haemoglobin E/beta thalassaemia in the United Kingdom. Data were extracted to show outcomes (selective abortion or live birth) of all fetuses and the status of those born with a disorder (alive, dead, successful bone marrow transplant, or lost to follow-up) by parents' region of residence and ethnicity. FINDINGS: At the end of 1999 the register included 1074 patients, 807 of whom were alive and residing in the United Kingdom. A successful bone marrow transplant has been performed for 117 out of 581 (20%) patients born since 1975. Residents of Pakistani origin are now the main group at risk in the United Kingdom, replacing residents of Cypriot origin. This has led to a marked shift in the need for services from the south-east of England to the Midlands and the north of England. Despite the acceptability of prenatal diagnosis, the proportion of affected births remains 50% higher than would be expected, reflecting a widespread failure to deliver timely screening and counselling to carriers. Even though effective treatment is available the annual number of deaths is rising, indicating that better tolerated treatments are needed. CONCLUSION: A national diagnosis register is a powerful instrument for monitoring the treatment and prevention of inherited disorders and for highlighting correctable shortcomings. In view of the increasing possibilities for genetic screening there is a strong case for central funding for such databases within modern health services

Sampling bounds for 2-D vector field tomography

The tomographic mapping of a 2-D vector field from line-integral data in the discrete domain requires the uniform sampling of the continuous Radon domain parameter space. In this paper we use sampling theory and derive limits for the sampling steps of the Radon parameters, so that no information is lost. It is shown that if Δx is the sampling interval of the reconstruction region and xmax is the maximum value of domain parameter x, the steps one should use to sample Radon parameters ρ and θ should be: Δρ≤ Δx/√2 and Δθ≤Δx/((√2+2)|xmax|). Experiments show that when the proposed sampling bounds are violated, the reconstruction accuracy of the vector field deteriorates. We further demonstrate that the employment of a scanning geometry that satisfies the proposed sampling requirements also increases the resilience to noise

Μελέτη και καταγραφή των μεθόδων ιατρικής συμμόρφωσης και στατιστική ανάλυση του επιπέδου συμμόρφωσης των ασθενών μέσω mobile εφαρμογών

149 σ.Η παρούσα διπλωματική έχει ως στόχο να παρουσιάσει αρχικά την έννοια της "κινητής" υγείας (mobile health), καθώς και βασικές έννοιες και τεχνολογίες που συνδέονται με αυτήν. Θα αναλυθεί η σχέση της με τη βελτίωση της ποιότητας της υγείας και ειδικότερα με τη φαρμακευτική συμμόρφωση των ασθενών μέσω εφαρμογών (mobile applications) που έχουν αναπτυχθεί για έξυπνα τηλέφωνα (smartphones). Θα γίνει μια εκτενής αναφορά σε προγράμματα mHealth που έχουν πραγματοποιηθεί σε χώρες του αναπτυσσόμενου κόσμου, εστιάζοντας στα τεχνολογικά μέσα με τα οποία υλοποιήθηκαν όπως επίσης και στο σκοπό για τον οποίο έγιναν και στα αποτελέσματα που επέφερε η εφαρμογή τους. Πέρα από αυτές τις αναφορές, θα δοθεί ιδιαίτερη βαρύτητα στην έννοια της φαρμακευτικής συμμόρφωσης και τις παραμέτρους που σχετίζονται με αυτήν. Θα πραγματοποιηθεί μελέτη των σχετικών εφαρμογών για κινητά και λεπτομερής στατιστική ανάλυση των χαρακτηριστικών και των αποτελεσμάτων τους. Θα αξιολογηθούν οι εφαρμογές αυτές ως προς το επίπεδο συμμόρφωσης που κρίνεται ότι προσφέρουν ώστε να αναδυθούν οι καλύτερες και επικρατέστερες εφαρμογές και θα συγκριθούν μεταξύ τους ενδελεχώς προκειμένου να καταγραφούν τα πλεονεκτήματα και οι ελλείψεις που έχουν.The present thesis aims at first to present the meaning of mobile health, as well as the principles and the technologies which are related with it. We analyze mobile health's relation with the enhancement of the quality health level and especially with the patients' medication adherence through mobile applications for smartphones. We make an extensive report to mHealth projects which have been made in developing countries and we focus on the technological means which were used for it, as well as on the purpose for which the projects were made and on their outcome. Apart from these reports, we pay great attention to the meaning of medication adherence and its related parametres. We study relative mobile applications and we make a detailed statistical analysis of their characteristics and results. We rate these apps according to their offered compliance level, in order to present the best and most well-known apps. We compare the apps with each other in order to record their advantages and their lack of functionality which they probably have.Πέτρου Μαρί

Improved 2-D vector field reconstruction using virtual sensors and the Radon transform

This paper describes a method that allows one to recover both components of a 2-D vector field based on boundary information only, by solving a system of linear equations. The analysis is carried out in the digital domain and takes advantage of the redundancy in the boundary data, since these may be viewed as weighted sums of the local vector field’s Cartesian components. Furthermore, a sampling of lines is used in order to combine the available measurements along continuous tracing lines with the digitised 2-D space where the solution is sought. A significant enhancement in the performance of the proposed algorithm is achieved by using, apart from real data, also boundary data obtained at virtual sensors. The potential of the proposed method is demonstrated by presenting an example of vector field reconstruction

Virtual sensors for 2D vector field tomography

We consider the application of tomography to the reconstruction of 2-D vector fields. The most convenient sensor configuration in such problems is the regular positioning along the domain boundary. However, the most accurate reconstructions are obtained by sampling uniformly the Radon parameter domain rather than the border of the reconstruction domain. This dictates a prohibitively large number of sensors and impractical sensor positioning. In this paper, we propose uniform placement of the sensors along the boundary of the reconstruction domain and interpolation of the measurements for the positions that correspond to uniform sampling in the Radon domain. We demonstrate that when the cubic spline interpolation method is used, a 60 times reduction in the number of sensors may be achieved with only about 10% increase in the error with which the vector field is estimated. The reconstruction error by using the same sensors and ignoring the necessity of uniform sampling in the Radon domain is in fact higher by about 30%. The effects of noise are also examined