978 resultados para Small ferromagnetic particles


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An elevated particle number concentration (PNC) observed during nucleation events could play a significant contribution to the total particle load and therefore to the air pollution in the urban environments. Therefore, a field measurement study of PNC was commenced to investigate the temporal and spatial variations of PNC within the urban airshed of Brisbane, Australia. PNC was monitored at urban (QUT), roadside (WOO) and semi-urban (ROC) areas around the Brisbane region during 2009. During the morning traffic peak period, the highest relative fraction of PNC reached about 5% at QUT and WOO on weekdays. PNC peaks were observed around noon, which correlated with the highest solar radiation levels at all three stations, thus suggesting that high PNC levels were likely to be associated with new particle formation caused by photochemical reactions. Wind rose plots showed relatively higher PNC for the NE direction, which was associated with industrial pollution, accounting for 12%, 9% and 14% of overall PNC at QUT, WOO and ROC, respectively. Although there was no significant correlation between PNC at each station, the variation of PNC was well correlated among three stations during regional nucleation events. In addition, PNC at ROC was significantly influenced by upwind urban pollution during the nucleation burst events, with the average enrichment factor of 15.4. This study provides an insight into the influence of regional nucleation events on PNC in the Brisbane region and it the first study to quantify the effect of urban pollution on semi-urban PNC through the nucleation events. © 2012 Author(s).

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The purpose of this paper is to analyse how participants learn in small business advisory programmes and to explore the impact of these learning programmes on the development of reflective learning dispositions in participants. The research involves two case studies of small business advisory programmes in Queensland, a state of Australia. One involves training in the use of GPS/GIS technology amongst rural SMEs and the other seeks to develop improved management and operational capabilities in regional and metropolitan manufacturing SMEs. Face to face semi-structured interviews were conducted throughout rural, regional and metropolitan Queensland with participants, trainers and senior executives in the administering organisations that ran the programmes. Learning in these programmes occurs through a combination of interaction with others and the adoption of practice-based and learner-centred processes. The impact of the programmes on participants includes the development of reflective learning dispositions, improved confidence in learning and appreciation of the value of new knowledge to their business. The research suggests that small business training programmes have the potential to affect the development of critical reflective learning dispositions in participants which is of fundamental importance to the development of a learning or knowledge economy.

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The world is facing problems due to the effects of increased atmospheric pollution, climate change and global warming. Innovative technologies to identify, quantify and assess fluxes exchange of the pollutant gases between the Earth’s surface and atmosphere are required. This paper proposes the development of a gas sensor system for a small UAV to monitor pollutant gases, collect data and geo-locate where the sample was taken. The prototype has two principal systems: a light portable gas sensor and an optional electric–solar powered UAV. The prototype will be suitable to: operate in the lower troposphere (100-500m); collect samples; stamp time and geo-locate each sample. One of the limitations of a small UAV is the limited power available therefore a small and low power consumption payload is designed and built for this research. The specific gases targeted in this research are NO2, mostly produce by traffic, and NH3 from farming, with concentrations above 0.05 ppm and 35 ppm respectively which are harmful to human health. The developed prototype will be a useful tool for scientists to analyse the behaviour and tendencies of pollutant gases producing more realistic models of them.

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Exposure to ultrafine particles (diameter less than 100 nm) is an important topic in epidemiological and toxicological studies. This study used the average particle number size distribution data obtained from our measurement survey in major micro-environments, together with the people activity pattern data obtained from the Italian Human Activity Pattern Survey to estimate the tracheobronchial and alveolar dose of submicrometer particles for different population age groups in Italy. We developed a numerical methodology based on Monte Carlo method, in order to estimate the best combination from a probabilistic point of view. More than 106 different cases were analyzed according to a purpose built sub-routine and our results showed that the daily alveolar particle number and surface area deposited for all of the age groups considered was equal to 1.5 x 1011 particles and 2.5 x 1015 m2, respectively, varying slightly for males and females living in Northern or Southern Italy. In terms of tracheobronchial deposition, the corresponding values for daily particle number and surface area for all age groups was equal to 6.5 x 1010 particles and 9.9 x 1014 m2, respectively. Overall, the highest contributions were found to come from indoor cooking (female), working time (male) and transportation (i.e. traffic derived particles) (children).

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Evasion of apoptosis contributes to both tumourigenesis and drug resistance in non-small cell lung carcinoma (NSCLC). The pro-apoptotic BCL-2 family proteins BAX and BAK are critical regulators of mitochondrial apoptosis. New strategies for targeting NSCLC in a mitochondria-independent manner should bypass this common mechanism of apoptosis block. BRCA1 mutation frequency in lung cancer is low; however, decreased BRCA1 mRNA and protein expression levels have been reported in a significant proportion of lung adenocarcinomas. BRCA1 mutation/deficiency confers a defect in homologous recombination DNA repair that has been exploited by synthetic lethality through inhibition of PARP (PARPi) in breast and ovarian cells; however, it is not known whether this same synthetic lethal mechanism exists in NSCLC cells. Additionally, it is unknown whether the mitochondrial apoptotic pathway is required for BRCA1/PARPi-mediated synthetic lethality. Here we demonstrate that silencing of BRCA1 expression by RNA interference sensitizes NSCLC cells to PARP inhibition. Importantly, this sensitivity was not attenuated in cells harbouring mitochondrial apoptosis block induced by co-depletion of BAX and BAK. Furthermore, we demonstrate that BRCA1 inhibition cannot override platinum resistance, which is often mediated by loss of mitochondrial apoptosis signalling, but can still sensitize to PARP inhibition. Finally we demonstrate the existence of a BRCA1-deficient subgroup (11–19%) of NSCLC patients by analysing BRCA1 protein levels using immunohistochemistry in two independent primary NSCLC cohorts. Taken together, the existence of BRCA1-immunodeficient NSCLC suggests that this molecular subgroup could be effectively targeted by PARP inhibitors in the clinic and that PARP inhibitors could be used for the treatment of BRCA1-immunodeficient, platinum-resistant tumours.

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Software as a Service (SaaS) is a promising approach for Small and Medium Enterprises (SMEs) firms, in particular those that are focused on growing fast and leveraging new technology, due to the potential benefits arising from its inherent scalability, reduced total cost of ownership and the ease of access to global innovations. This paper proposes a dynamic perspective on IS capabilities to understand and explain SMEs sourcing and levering SaaS. The model is derived from combining the IS capabilities of Feeny and Willcocks (1998) and the dynamic capabilities of Teece (2007) and contextualizing it for SMEs and SaaS. We conclude that SMEs sourcing and leveraging SaaS require leadership, business systems thinking and informed buying for sensing and seizing SaaS opportunities and require leadership and vendor development for transforming in terms of aligning and realigning specific tangible and intangible assets.

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The often competing imperatives of equity, simplicity and efficiency in the income tax regime, particularly the notion of simplicity, has been most evident within Australia’s small business sector over the last decade. In an attempt to provide tax simplification and reduce the tax compliance burden faced by Australian small businesses, provisions collectively referred to as the ‘simplified tax system’ or STS were introduced. The STS was designed to provide eligible small businesses with the option of adopting a range of ‘simplified’ tax measures designed to simplify their tax affairs whilst at the same time, reducing their tax compliance costs. Ultimately, a low take-up rate and accompanying criticisms led to a remodelled and rebadged concessionary regime known as the ‘Small Business Entity’ (SBE) regime which came into effect from 1 July 2007. This paper, through a pilot study, investigates the SBE regime though the eyes of the practitioner. In line the Australian Federal Government’s objective of simplification and reduced compliance costs, the purpose of the study was to (1) determine the extent to which the SBE concessions are being adopted by tax practitioners on behalf of their clients, (2) gain an understanding as to which individual SBE tax concessions are most favoured by practitioners, (3) determine the primary motivation as to why tax practitioners recommend particular SBE concessions to their clients, and (4) canvass the opinions of practitioners as to whether they believed that the introduction of the SBE concessions had met their stated objective of reducing tax compliance costs for small businesses. The findings of this research indicate that, while there is a perception that the SBE concessions are worth embracing, contrary to the policy intent, the reasons behind adopting the concessions was the opportunity to minimise a clients’ tax liability. It was revealed that adopting particular concessions had nothing to do with compliance costs savings and, in fact, the SBE concessions merely added another layer of complexity to an already cumbersome and complex tax code, which resulted in increased compliance costs for their small businesses clients. Further, the SBE concessions allowed tax practitioners the opportunity to engage in effective tax minimisation, thereby fulfilling the client advocacy role of the tax practitioner in maximising their clients’ tax preferences.

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The prevalence of International New Ventures (INVs) has increased during the past twenty years. Nevertheless, to date there has been no general consensus within the literature on an explanation as to the rapid internationalisation of some firms. Do they follow a similar process to other firms that internationalise based on a more ‘measured’ incremental sequential process of internationalisation. This paper proposes and tests an innovation diffusion model of the internationalisation of small firm INVs and others by drawing on key innovation diffusion models from the literature. The results of this analysis indicate that the synthesised model of export adoption is effective in explaining the internationalisation process of INVs and other firms within the Queensland Food and Beverage Industry. Significantly, the features of the original innovation diffusion models developed in the consumer behaviour literature, which had limited examination within the internationalisation literature, were confirmed. This includes the ability of firms, or specifically decision-makers, to skip stages based on previous experience.

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The purpose of this study was to investigate the effect of very small air gaps (less than 1 mm) on the dosimetry of small photon fields used for stereotactic treatments. Measurements were performed with optically stimulated luminescent dosimeters (OSLDs) for 6 MV photons on a Varian 21iX linear accelerator with a Brainlab μMLC attachment for square field sizes down to 6 mm × 6 mm. Monte Carlo simulations were performed using EGSnrc C++ user code cavity. It was found that the Monte Carlo model used in this study accurately simulated the OSLD measurements on the linear accelerator. For the 6 mm field size, the 0.5 mm air gap upstream to the active area of the OSLD caused a 5.3 % dose reduction relative to a Monte Carlo simulation with no air gap. A hypothetical 0.2 mm air gap caused a dose reduction > 2 %, emphasizing the fact that even the tiniest air gaps can cause a large reduction in measured dose. The negligible effect on an 18 mm field size illustrated that the electronic disequilibrium caused by such small air gaps only affects the dosimetry of the very small fields. When performing small field dosimetry, care must be taken to avoid any air gaps, as can be often present when inserting detectors into solid phantoms. It is recommended that very small field dosimetry is performed in liquid water. When using small photon fields, sub-millimetre air gaps can also affect patient dosimetry if they cannot be spatially resolved on a CT scan. However the effect on the patient is debatable as the dose reduction caused by a 1 mm air gap, starting out at 19% in the first 0.1 mm behind the air gap, decreases to < 5 % after just 2 mm, and electronic equilibrium is fully re-established after just 5 mm.