Bacterial atmospheric contamination during routine dental activity

Routine dental procedures cause atmospheric bacterial contamination in the dental clinic and laboratory. This environmental hazard, quantified by the Air Microbial Index, was shown in our study to be directly related to aerosol creating instruments and ventilation.peer-reviewe

Bacterial cross-contamination between the dental clinic and laboratory during prosthetic treatment

Prosthetic treatment involves various stages in construction. This may result in cross-contamination between the dental clinic and laboratory. According to results obtained from the study, recommendations were made so as to reduce as much as possible cross-contamination, making a safer environment for the dental team and patient.peer-reviewe

Generic medicine prices and their distribution in Malta

Objectives: To analyse the composition of the private pharmaceutical retail market in Malta on the basis of the originator or generic status of available medicines and to observe the change in prices of generics and originators over time. Method: The prices of a sample (n=435) of medicines in Malta were analysed for an eight year period (2002 to 2009). The variation in price in the generic and originator segments was calculated. Thirty-one active ingredients with generics available were identified and the Average Retail Price Per Unit (ARPPU) and the Lowest Retail Price Per Unit (LRPPU) were calculated. The average discount from the originator price was calculated, per compound and also by drug class. Key Findings: The sample population contained 17.2% generic products. The mean drop in the ARPPU was of 10.87% and for the LRPPU of 21.42% for the LRPU. The average discount was 14.59% in 2002 and 37.19% in 2009. Conclusion: The number of generic medicines in Malta has increased in the last eight years, with a consequent decrease in the lowest prices available for the set of medicinal compounds.peer-reviewe

Generic medicine prices and their distribution in Malta

Objectives: To analyse the composition of the private pharmaceutical retail market in Malta on the basis of the originator or generic status of available medicines and to observe the change in prices of generics and originators over time. Method: The prices of a sample (n=435) of medicines in Malta were analysed for an eight year period (2002 to 2009). The variation in price in the generic and originator segments was calculated. Thirty-one active ingredients with generics available were identified and the Average Retail Price Per Unit (ARPPU) and the Lowest Retail Price Per Unit (LRPPU) were calculated. The average discount from the originator price was calculated, per compound and also by drug class. Key Findings: The sample population contained 17.2% generic products. The mean drop in the ARPPU was of 10.87% and for the LRPPU of 21.42% for the LRPU. The average discount was 14.59% in 2002 and 37.19% in 2009. Conclusion: The number of generic medicines in Malta has increased in the last eight years, with a consequent decrease in the lowest prices available for the set of medicinal compounds.peer-reviewe

Machine learning for galaxy morphology classification

In this work, decision tree learning algorithms and fuzzy inferencing systems are applied for galaxy morphology classification. In particular, the CART, the C4.5, the Random Forest and fuzzy logic algorithms are studied and reliable classifiers are developed to distinguish between spiral galaxies, elliptical galaxies or star/unknown galactic objects. Morphology information for the training and testing datasets is obtained from the Galaxy Zoo project while the corresponding photometric and spectra parameters are downloaded from the SDSS DR7 catalogue.peer-reviewe

Polyamine metabolism in mycorrhizal fungi

The polyamine biosynthetic enzymes arginine decarboxylase (ADC), ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (AdoMetDC), and spermidine synthase, are susceptible to inhibition by a variety of compounds originally developed for the inhibition of polyamine biosynthesis in animal cells as an approach to cancer treatment. These compounds have subsequently been used in the study of polyamine metabolism in plants, fungi, bacteria, and protozoa, with important consequences. For example, most fungi are considered to possess only ODC for the initial step in polyamine biosynthesis, whilst plants have both ODC and ADC enzymes. Therefore, specific inhibition of ornithine decarboxylation in a plant-pathogenic fungus should inhibit fungal growth without damaging tire host plant. In fact, such an approach to plant disease control has been realised. Difluoromethylarginine (DFMA) and difluoromethylornithine (DFMO) are inhibitors of ADC and ODC, respectively. Cyclohexylamine (CHA) is a spermidine synthase inhibitor, and methylglyoxal bis (guanylhydrazone) (MGBG), an inhibtor of AdoMetDC. Mycorrhizal fungi, which are intimately associated with most plants, and which are of benefit in terrestrial ecosystems, may be vulnerable to compounds affecting polyamine metabolism. This premise was investigated in the ectomycorrhizal fungi Laccaria proximo, Paxillus involutus, Hebeloma mesophaeum, and Thelephora terrestris. Furthermore, in view of the pivotal role of polyamines in organisms, the importance of polyamines in stress responses in plants, and the fact that many mycorrhizal fimgi are tolerant of industrially-polluted soils, polyamine metabolism was studied in P. involutus following exposure of the fungus to toxic metals. Exposure of L. proximo to DFMO led to decreased growth, whilst exposure of the fungus to DFMA enhanced growth. The following data indicate that L. proximo possesses both ADC and ODC activities: (1) DFMA depleted putrescine and did not inhibit ODC activity; (2) incubation of mycelium with a [U-14C]arginine substrate led to [C]putrescine formation; (3) DFMA completely inhibited the formation of polyamines from [U-14C]arginine; (4) DFMO inhibited bound biosynthetic enzyme activity and the formation of putrescine from [U-14C]ornithine. Although exposure of P. involutus to DFMO resulted in reduced growth, and reduced activities of ODC, AdoMetDC and diamine oxidase, this was not accompanied by reductions in polyamine concentrations. Indeed, spermine concentration was substantially increased. Together, these data suggest the existence of a mechanism in P. involutus to maintain intracellular concentrations of free polyamines. H. mesophaeum exhibited a notable lack of response to inhibitor treatments, the possibilities for which are discussed in Chapter 3. The substantial depletion in spermine in T. terrestris, leading to a reduction in growth, following DFMO treatment, suggests tlie importance of this polyamine for growth in T. terrestris, in common with other fungi. Radiolabelled compounds that co-chromatographed with authentic standards of cadaverine, aminopropylcadaverine (APC) and N,N' bis (3 aminopropyl)cadaverine (3 APC), were isolated from reaction mixtures after the decarboxylation of [U-14C]lysine by fungal extracts. The identity of 3 APC was confirmed by nuclear magnetic resonance spectroscopy. In subsequent work, the inhibition of AdoMetDC and spermidine synthase led to significant reductions in the recovery of radiolabelled 3 APC. Results show that a range of ectomycorrhizal and plant-pathogenic fungi can synthesise cadaverine and its higher homologues APC and 3 APC, in reactions catalysed by AdoMetDC and spermidine synthase. Furthermore, these compounds may also be synthesised from the condensation of cadaverine and L-aspartic-p-semialhehyde. Biosynthetic enzyme activity, polyamine concentrations and the rate of conversion of lysine into cadaverine were measured in P. involutus following exposure of the fungus to copper, nickel, lead, or zinc. Metal ions were accumulated in the fungus. Although the concentrations of putrescine, spermidine and spermine were affected to some extent, with copper and nickel treatments associated with reductions in spermidine concentration, these variations in polyamine concentrations did not significantly affect fungal fresh weight. Accumulation of metals in fungal tissues, and exclusion of ions from the cell by sequestration at extracellular sites, are among the mechanisms that would tend to limit metal toxicity in mycorrhizal plants

Machine learning for benthic sand and maerl classification and coverage estimation in coastal areas around the Maltese Islands

Analysis of the seabed composition over a large spatial scale is an interesting yet very challenging task. Apart from the field work involved, hours of video footage captured by cameras mounted on Remote Operated Vehicles (ROVs) have to be reviewed by an expert in order to classify the seabed topology and to identify potential anthropogenic impacts on sensitive benthic assemblages. Apart from being time consuming, such work is highly subjective and through visual inspection alone, a quantitative analysis is highly unlikely to be made. This study investigates the applicability of various Machine Learning techniques for the automatic classification of the seabed into maerl and sand regions from recorded ROV footage. ROV data collected from depths ranging between 50 m and 140 m and at 9.5 km from the northeast coastline of the Maltese Islands, is processed. Through the application of the presented technique, 5.23 GB of data corresponding to 2 h and 24 min of footage which was collected during June 2013, was initially cleaned and classified. An estimate for the percentage cover of the two benthic habitats (sandy seabed and maerl) was also computed by using artifacts encountered during the ROV survey and of known dimensions as a reference. Unlike other automatic seabed mapping techniques, the presented prototype processes video footage captured by a down-facing camera and not through acoustic backscatter. Image data is easier and much cheaper to capture. Promising results that indicate a very good degree of agreement between the true and predicted habitat type distribution values, were obtained.peer-reviewe

Genetic optimization for radio interferometer configurations

The large bandwidth and resolution specifications of today’s telescopes require the use of different types of collectors positioned over long baselines. Innovative feeds and detectors must be designed and introduced in the initial phases of development. The required level of resolution can only be achieved through a ground-breaking configuration of dishes and antennas. This work investigates the possibility of the genetic optimization of radio interferometer layouts given constraints on cable length, required UV density distribution and point-spread function. Owing to the large collecting area and the frequency range required for the Square Kilometre Array (SKA) to deliver the promised science, the configuration of the dishes within each station is an important issue. As a proof of concept, the Phase 1 specifications of this telescope are used to test the proposed framework.peer-reviewe

Control strategies for late blight in organic potato production

This report was presented at the UK Organic Research 2002 Conference. Protective copper fungicides are currently used to control late blight in most organic production systems, but approval for their use in organic farming will be revoked in 2002. Evidence suggests that organic potato production will not be reliably economic in the absence of Cu. Current controls for late blight are reviewed including: variety selection/breeding for blight resistance, diversification strategies, agronomic strategies for the management of late blight, and alternative treatments to Cu-fungicides

Novice programmers and the problem description effect.

It is often debated whether a problem presented in a straightforward minimalist fashion is better, or worse, for learning than the same problem presented with a real-life or concrete context. The presentation, contextualization, or problem description has been well studied over several decades in disciplines such as mathematics education and psychology; however, little has been published in the field of computing education. In psychology it has been found that not only the presence of context, but the type of context can have dramatic results on problem success. In mathematics education it has been demonstrated that there are non-mathematical factors in problem presentation that can affect success in solving the problem and learning. The contextual background of a problem can also impact cognitive load, which should be considered when evaluating the effects of context. Further, it has been found that regarding cognitive load, computer science has unique characteristics compared to other disciplines, with the consequence that results from other disciplines may not apply to computer science, thus requiring investigation within computer science. This paper presents a multi-national, multi-institutional study of the effects of problem contextualization on novice programmer success in a typical CS1 exercise