Assessment of annual whole-body occupational radiation exposure in medical practice in Ghana (2000-09)

Occupational exposure to radiation in medical practice in Ghana has been analysed for a 10-y period between 2000 and 2009. Monitored dose data in the medical institution in Ghana from the Radiation Protection Institute's database were extracted and analysed in terms of three categories: diagnostic radiology, radiotherapy and nuclear medicine. One hundred and eighty medical facilities were monitored for the 10-y period, out of which ~98% were diagnostic radiology facilities. Only one nuclear medicine and two radiotherapy facilities have been operational in the country since 2000. During the 10-y study period, monitored medical facilities increased by 18.8%, while the exposed workers decreased by 23.0%. Average exposed worker per entire medical institution for the 10-y study period was 4.3. Annual collective dose received by all the exposed workers reduced by a factor of 4 between 2000 and 2009. This is seen as reduction in annual collective doses in diagnostic radiology, radiotherapy and nuclear medicine facilities by ~76, ~72 and ~55%, respectively, for the 10-y period. Highest annual collective dose of 601.2 man mSv was recorded in 2002 and the least of 142.6 man mSv was recorded in 2009. Annual average values for dose per institution and dose per exposed worker decreased by 79 and 67.6%, respectively between 2000 and 2009. Average dose per exposed worker for the 10-y period was least in radiotherapy and highest in diagnostic radiology with values 0.14 and 1.05 mSv, respectively. Nuclear medicine however recorded average dose per worker of 0.72 mSv. Correspondingly, range of average effective doses within the diagnostic radiology, radiotherapy and nuclear medicine facilities were 0.328-2.614, 0.383-0.728 and 0.448-0.695 mSv, respectively. Throughout the study period, an average dose per medical institution of 3 mSv and an average dose per exposed worker of 0.69 mSv were realised. Exposed workers in diagnostic radiology primarily received most of the individual annual doses >1 mSv. The entire study period had 705 instances in which exposed workers received individual annual doses >1 mSv. On thermoluminescent dosemeter (TLD) return rates, facilities in Volta and Eastern Regions recorded highest return rates of 94.3% each. Ashanti Region recorded the least TLD return rate with 76.7%.     

Implementation of dose management system at radiation protection board of Ghana Atomic Energy Commission

The dose management system (DMS) is a computer software developed by the International Atomic Energy Agency for managing data on occupational exposure to radiation sources and intake of radionuclides. It is an integrated system for the user-friendly storage, processing and control of all existing internal and external dosimetry data. The Radiation Protection Board (RPB) of the Ghana Atomic Energy Commission has installed, customised, tested and using the DMS as a comprehensive DMS to improve personnel and area monitoring in the country. Personnel dose records from the RPBs database from 2000 to 2009 are grouped into medical, industrial and education/research sectors. The medical sector dominated the list of monitored institutions in the country over the 10-y period representing ～87 %, while the industrial and education/research sectors represent ～9 and ～4 %, respectively. The number of monitored personnel in the same period follows a similar trend with medical, industrial and education/research sectors representing ～74, ～17 and ～9 %, respectively. Analysis of dose data for 2009 showed that there was no instance of a dose above the annual dose limit of 20 mSv, however, 2.7 % of the exposed workers received individual annual doses >1 mSv. The highest recorded individual annual dose and total collective dose in all sectors were 4.73 mSv and 159.84 man Sv, respectively. Workers in the medical sector received higher individual doses than in the other two sectors, and average dose per exposed worker in all sectors is 0.25 mSv.     

Oleic-acid-coated CoFe2O4 nanoparticles synthesized by co-precipitation and hydrothermal synthesis

Oleic-acid-coated CoFe₂O₄ nanoparticles were synthesized by co-precipitation and hydrothermal synthesis. The coprecipitation of the nanoparticles was achieved by the rapid addition of a strong base to an aqueous solution of cations in the presence of the oleic acid surfactant, or without this additive. The nanoparticles were also synthesized by a hydrothermal treatment of suspensions of the precipitates, coprecipitated at room temperature in the presence of the oleic acid, or without it. The influence of the synthesis conditions, such as the valence state of the iron cation in the starting aqueous solution, the temperature of the treatment and the presence of oleic acid, on the particles size was systematically studied. X-ray powder diffractometry (XRD) and transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDS) revealed that, although spinel forms at room temperature, a substantial amount of Co was incorporated within the secondary, feroxyhyte-like phase when the iron cation was in the 2+ state. In contrast, when iron was in the 3+ state, the spinel forms at elevated temperatures of approximately 60 °C. The presence of the oleic acid further increased the formation temperature for the stoichiometric spinel. Moreover, the oleic acid impeded the particles’ growth and enabled the preparation of colloidal suspensions of the nanoparticles in non-polar organic solvents. The nanoparticles’ size was successfully controlled by the temperature of the synthesis in the region where superparamagnetism dominates to the region where mono-domain ferrimagnetism dominates the magnetic properties.     

The application of thick-film technology in C-MEMS

Laminated 3D structures made using low-temperature co-fired ceramic (LTCC) technology are practical for ceramic micro-electro-mechanical systems (C-MEMS). The sensors for mechanical quantities, and/or actuators, are fundamental parts of MEMS. Thick-film resistors can be used to sense the mechanical deformations, and thick-film piezoelectric materials can be used as electro-mechanical transducers in a C-MEMS structure. The integration of these thick-film materials on LTCC substrates is in some cases difficult to realise due to interactions with the rather glassy LTCC substrates. The subject of our work is an investigation of thick-film materials for electro-mechanical transducers (sensors and actuators) and their compatibility with LTCC substrates. Resistors made with commercial thick-film resistor materials for use as sensors on LTCC substrates have been investigated and evaluated. Ferroelectric ceramic materials based on solid solutions of lead zirconate titanate (PZT) with low firing temperatures around 850°C were developed for thick-film technology and evaluated on LTCC substrates.     

TestEra: Specification-Based Testing of Java Programs Using SAT

TestEra is a framework for automated specification-based testing of Java programs. TestEra requires as input a Java method (in sourcecode or bytecode), a formal specification of the pre- and post-conditions of that method, and a bound that limits the size of the test cases to be generated. Using the method's pre-condition, TestEra automatically generates all nonisomorphic test inputs up to the given bound. It executes the method on each test input, and uses the method postcondition as an oracle to check the correctness of each output. Specifications are first-order logic formulae. As an enabling technology, TestEra uses the Alloy toolset, which provides an automatic SAT-based tool for analyzing first-order logic formulae. We have used TestEra to check several Java programs including an architecture for dynamic networks, the Alloy-alpha analyzer, a fault-tree analyzer, and methods from the Java Collection Framework.     

A system identification approach to the modelling of pulsed eddy-current systems

The purpose of this article is to present a novel approach in the modelling of pulsed eddy-current systems. Frequency-domain finite element analysis is used to build up a z-domain, finite impulse response (FIR) model. The FIR model allows excitation to be varied without need for the field analysis to be performed again. Furthermore, the proposed approach to the modelling of the system function allows unequal spacing of the frequency samples. This enables greater accuracy of the modelling in the frequency range where the magnitude or phase response of the system varies greatly. The proposed approach was validated on a pulsed remote-field eddy-current system in a ferromagnetic tube. Excellent agreement between predicted and measured response was achieved.     

Application of neural networks with orthogonal activation functions in control of dynamical systems

In this article, we present a new method for the synthesis of almost and quasi-orthogonal polynomials of arbitrary order. Filters designed on the bases of these functions are generators of generalised quasi-orthogonal signals for which we derived and presented necessary mathematical background. Based on theoretical results, we designed and practically implemented generalised first-order (k = 1) quasi-orthogonal filter and proved its quasi-orthogonality via performed experiments. Designed filters can be applied in many scientific areas. In this article, generated functions were successfully implemented in Nonlinear Auto Regressive eXogenous (NARX) neural network as activation functions. One practical application of the designed orthogonal neural network is demonstrated through the example of control of the complex technical non-linear system – laboratory magnetic levitation system. Obtained results were compared with neural networks with standard activation functions and orthogonal functions of trigonometric shape. The proposed network demonstrated superiority over existing solutions in the sense of system performances.     

Polyphenolic Composition of the Berry Skin of Six Fungus-Resistant Red Grapevine Varieties

Phenolic compound profiles were investigated by high-performance liquid chromatography-diode array detector in three vintages to assess genotypic variation in berry skins of six resistant grapevine varieties: “Cabernet Cortis,” “Chancellor,” “Léon Millot,” “Maréchal Foch,” “Monarch,” and “Regent.” The research has revealed a significant difference among the varieties in the total phenolic content, anthocyanins, flavanols, and flavan-3-ols. A clear differentiation of all varieties by means of the polyphenol profile using discriminant analyses has been achieved. “Regent” reached the significantly highest total polyphenol content, as well as total anthocyanin and total flavonol content. The polyphenol profile of “Chancellor” was quite different from all of the other studied varieties. Although being closely related, “Maréchal Foch” and “Léon Millot” showed qualitatively and quantitatively quite different polyphenol contents. No clear connection between the genetic origin of the varieties and their polyphenol profiles has been found.     

Assessing the impact of meta-model evolution: a measure and its automotive application

Software and Systems Modeling - Domain-specific meta-models play an important role in the design of large software systems by defining language for the architectural models. Such common modeling...