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Theory of secure network coding
No full textIn this tutorial paper, we focus on the basic theory of linear secure network coding. Our goal is to present fundamental results and provide preliminary knowledge for anyone interested in the area. We first present a model for secure network coding and then a necessary and sufficient condition for a linear network code to be secure. Optimal methods to construct linear secure network codes are also provided. For further investigation of the secure properties of linear network codes, we illuminate different secure criteria and requirements, with a few alternative models.
NRM engagement between remote dryland communities and government agencies: success factors from Australia
No full textThe management of dryland environments involves the interaction of multiple government agencies and citizens, and is required to respond to a wide range of responsibilities and aspirations for a given region. This paper focuses on the characteristics of engagement between management agencies and citizens in a dryland region, presented here as a series of success factors. These factors are based on empirical research carried out in the Lake Eyre Basin in Australia, one of the world’s largest inwardly draining basins. The results reinforce generic and dryland-specific factors supporting successful community engagement. The former, such as building trust, working in partnership, supporting community champions, and maintaining transparency, are necessary but insufficient for achieving successful community engagement in the case study region. In addition, community engagement in the case study region also required respecting the extreme conditions and extraordinary variability of the Basin and committing to longer timeframes even if the outcomes of community engagement are slow to accrue, in order to take advantage of opportunities in more prosperous times.
Method for the generation of surface-bound nanoparticle density gradients
No full textWe report a novel, versatile method for generating number density gradients of individual gold (Au) and silver (Ag) nanoparticles by a two-step method. First, a chemical gradient of amine surface functional groups is deposited by plasma copolymerization. Second, a density gradient of nanoparticles is formed by the immersion of the chemical gradient in solutions of nanoparticles. Chemical characterization by X-ray photoelectron spectroscopy and morphological analysis by atomic force microscopy shows that nanoparticle density closely follows the change in nitrogen surface concentration across the gradients. We also demonstrate that it is possible to control the slope of the gradients by using nanoparticle solutions of different concentrations. Important for technological and research applications, this method can be used with nanoparticles of various sizes and different materials. In addition, the use of plasma deposition allows such gradients to be generated on any type of substrate.
Transport of copper as affected by titania nanoparticles in soil columns
No full textThe effects of TiO2 nanoparticles on the transport of Cu through four different soil columns were studied. For two soils (HB and DX), TiO2 nanoparticles acted as a Cu carrier and facilitated the transport of Cu. For a third soil (BJ) TiO2 nanoparticles also facilitated Cu transport but to a much lesser degree, but for a fourth soil (HLJ) TiO2 nanoparticles retarded the transport of Cu. Linear correlation analysis indicated that soil properties rather than sorption capacities for Cu primary governed whether TiO2 nanoparticlesfacilitated Cu transport. The TiO2-associated Cu of outflow in the Cu-contaminated soil columns was significantly positively correlated with soil pH and negatively correlated with CEC and DOC. During passage through the soil columns 46.6e99.9% of Cu initially adsorbed onto TiO2 could be “stripped” from nanoparticles depending on soil, where Cu desorption from TiO2 nanoparticles increased with decreasing flow velocity and soil pH.
Periconceptional nutrition and the early programming of a life of obesity or adversity
No full textWomen entering pregnancy with a high body weight and fat mass have babies at increased risk of becoming overweight or obese in childhood and later life. It is not known, whether exposure to a high level of maternal nutrition before pregnancy and exposure to a high transplacental nutrient supply in later pregnancy act through similar mechanisms to program later obesity. Using the pregnant sheep we have shown that maternal overnutrition in late pregnancy results in an upregulation of PPARg activated genes in fetal visceral fat and a subsequent increase in the mass of subcutaneous fat in the postnatal lamb. Exposure to maternal overnutrition during the periconceptional period alone, however, results in an increase in total body fat mass in female lambs only with a dominant effect on visceral fat depots. Thus the early programming of later obesity may result from ‘two hits’, the first occurring as a result of maternal overnutrition during the periconceptional period and the second occurring as a result of increased fetal nutrition in late pregnancy. Whilst a short period of dietary restriction during the periconceptional period reverses the impact of periconceptional overnutrition on the programming of obesity, it also results in an increased lamb adrenal weight and cortisol stress response, together with changes in the epigenetic state of the insulin like growth factor 2 (IGF2) gene in the adrenal. Thus, not all of the effects of dietary restriction in overweight or obese mother in the periconceptional period may be beneficial in the longer term.
Towards creative case based reasoning
No full textCase Based Reasoning (CBR) solves new problems by re-using the old solutions in similar contexts. However, repetition of previous solutions in new situations is not creative and thus becomes an issue to CBR, considering the fact that creativity is required to solve new problems. The majority of existing CBR applications is still used for solving routine problems. Consequently, this paper firstly identifies the possible root causes that may restrict the CBR method to be applied into creative problem-solving tasks. Then, in order to address the CBR issue in creativity, a concept of Creative Case Based Reasoning (CCBR) is proposed, which not only re-highlights the importance of creativity in CBR, but also serves as an initiative for exploring the CBR’s potential in generating creative solutions. Finally, this paper is summarised with concluding remarks.