Work domain analysis and intelligent transport systems: Implications for vehicle design

This article presents a Work Domain Analysis (WDA) of the road transport system in Victoria, Australia. A series of driver information requirements and tasks that could potentially be supported through the use of Intelligent Transport Systems (ITS) are then extracted from the WDA. The potential use of ITS technologies to circumvent these information gaps and provide additional support to drivers is discussed. It is concluded that driver information requirements are currently not entirely satisfied by contemporary vehicle design and also that there are a number of driving tasks that could be further supported through the provision of supplementary systems within vehicles

Quantitative study on the effects of sugars on membrane phase transitions - preliminary investigations

It is well known that sugars and other small solutes can reduce the temperature at which membranes undergo the fluid-gel phase transition at low hydration. The mechanisms for this are now well understood [Bryant et al. Abstract No. 85]. Naively, one might expect that this ability would be a direct function of sugar concentration, and that the effects should increase as the amount of sugar increases. However, the real situation is more complex. Previous work [K.L. Koster, Y.P. Lei, M. Anderson, S. Martin, G. Bryant, Biophys. J. 78 (2000) 1932–1946.] has shown that there are two distinct mechanisms for reduction in the transition temperature: first, if the sugar concentration is too low to form a glass, then the transition temperature can be reduced to (at best) the full hydration value; and second, if a glass forms, the transition temperature can be depressed to a fixed value, largely independent of sugar concentration. However, to the authors’ knowledge there has been no systematic study of the membrane transition temperature as a function of sugar/lipid ratio and level of hydration. In this paper we present the results of such a study. We show that in the absence of a glass, the reduction in the membrane phase transition temperature reaches a maximum value at a limiting sugar:lipid ratio. Beyond that value, the addition of further sugar no longer alters the membrane phase transition temperature. We explain these results in terms of hydration forces between membranes, and comment on the implications of these results for the prevention of damage to membranes during dehydration

How much solute is needed to inhibit the fluid to gel membrane phase transition at low hydration?

We present a quantitative study of the effect of sugars on the membrane gel-fluid phase transition as a function of sugar:lipid ratio. We show that the maximum effect occurs at around 1.5 sugar rings per molecule for both mono- and di-saccharides. We present a theoretical model to try to explain these results, and discuss the assumptions inherent in the model

Effects of sugars on lipid bilayers during dehydration - SAXS/WAXS measurements and quantitative model

We present an X-ray scattering study of the effects of dehydration on the bilayer and chain-chain repeat spacings of dipalmitoylphosphatidylcholine bilayers in the presence of sugars. The presence of sugars has no effect on the average spacing between the phospholipid chains in either the fluid or gel phase. Using this finding, we establish that for low sugar concentrations only a small amount of sugar exclusion occurs. Under these conditions, the effects of sugars on the membrane transition temperatures can be explained quantitatively by the reduction in hydration repulsion between bilayers due to the presence of the sugars. Specific bonding of sugars to lipid headgroups is not required to explain this effect

Kinetics of the lamellar gel-fluid transition in phosphatidylcholine membranes in the presence of sugars

Phase diagrams are presented for dipalmitoylphosphatidylcholine (DPPC) in the presence of sugars (sucrose) over a wide range of relative humidities (RHs). The phase information presented here, determined by small angle X-ray scattering (SAXS), is shown to be consistent with previous results achieved by differential scanning calorimetry (DSC). Both techniques show a significant effect of sucrose concentration on the phase behaviour of this phospholipid bilayer. An experimental investigation into the effect of sugars on the kinetic behaviour of the gel to fluid transition is also presented showing that increasing the sugar content appears to slightly increase the rate at which the transition occurs

Phospholipid membrane protection by sugar molecules during dehydration - insights into molecular mechanisms using scattering techniques

Scattering techniques have played a key role in our understanding of the structure and function of phospholipid membranes. These techniques have been applied widely to study how different molecules (e.g., cholesterol) can affect phospholipid membrane structure. However, there has been much less attention paid to the effects of molecules that remain in the aqueous phase. One important example is the role played by small solutes, particularly sugars, in protecting phospholipid membranes during drying or slow freezing. In this paper, we present new results and a general methodology, which illustrate how contrast variation small angle neutron scattering (SANS) and synchrotron-based X-ray scattering (small angle (SAXS) and wide angle (WAXS)) can be used to quantitatively understand the interactions between solutes and phospholipids. Specifically, we show the assignment of lipid phases with synchrotron SAXS and explain how SANS reveals the exclusion of sugars from the aqueous region in the particular example of hexagonal II phases formed by phospholipids

Location of sugars in multilamellar membranes at low hydration

Severe dehydration is lethal for most biological species. However, there are a number of organisms which have evolved mechanisms to avoid damage during dehydration. One of these mechanisms is the accumulation of small solutes (e.g. sugars), which have been shown to preserve membranes by inhibiting deleterious phase changes at low hydration. Specifically, sugars reduce the gel to fluid phase transition temperatures of model lipid/water mixtures. However, there is a debate about the precise mechanism, the resolution of which hinges on the location of the sugars. In excess water, it has been observed using contrast variation SANS that the sugar concentration in the excess phase is higher than in the interlamellar region [Deme and Zemb, J. Appl. Crystallog. 33 (2000) 569]. This raises two questions regarding the location of the sugars at low hydrations: first, does the system phase separate to give a sugar/water phase in equilibrium with a lipid/water/sugar lamellar region (with different sugar concentrations); and second, is the sugar in the interlamellar region uniformly distributed, or does it concentrate preferentially either in close proximity to the lipids, or towards the center of the interbilayer region. In this paper we present the preliminary results of measurements using contrast variation SANS to determine the location of sugars in lipid/water mixtures

Aflatoxin Contamination of Groundnut: Prospects for a Genetic Solution through Conventional Breeding

Af latoxin contamination of groundnut is a serious problem in most groundnut-producing countries. The aflatoxin-producing fungi, Aspergillus flavus and A. parasiticus, can invade groundnut seed in the field before harvest, during postharvest drying and curing, and in storage. The semi-arid tropical environment is conducive to preharvest contamination when the crop experiences drought before harvest, whereas in wet and humi d areas, postharvest contamination is more prevalent. Af latoxin contamination can be minimized by adopting some cultural, produce-handling, and storage practices. However, these practices have not been widely adopted by small farmers in developing countries which contribute about 60% of the world's groundnut product ion. Cultivars resistant to seed invasion by aflatoxin-producing fungi or to aflatoxin product ion woul d be of great value to farmers in both developed and developing countries. Therefore, breeding for resistance to aflatoxin-producing fungi and/or aflatoxin product ion can play a significant role in preventing aflatoxin contamination in groundnut , consequent economic losses, and health hazards. The alleviation of aflatoxin contamination through genetic manipulation has been at tempted since the mid 1970s. In spite of the significant progress achieved to date, these efforts have not resulted in complete freedom f rom aflatoxin contamination. The current status and future prospects of genetic solutions to the aflatoxin contamination problem are briefly discussed in this paper

Integrated biological-chemical control of Botrytis gray mould of chickpea

During 1994-96, Trichoderma viride and vinclozolin were used for the integrated control of B. cinerea on chickpeas in Pantnagar, Uttar Pradesh, India

Interpersonal effects of parents and adolescents on each other’s health behaviours: a dyadic extension of the theory of planned behaviour

Objective: Interpersonal relationships are important predictors of health outcomes and interpersonal influences on behaviours may be key mechanisms underlying such effects. Most health behaviour theories focus on intrapersonal factors and may not adequately account for interpersonal influences. We evaluate a dyadic extension of the Theory of Planned Behaviour by examining whether parent and adolescent characteristics (attitudes, subjective norms, perceived behavioural control and intentions) are associated with not only their own but also each other’s intentions/behaviours. Design: Using the Actor-Partner Interdependence Model, we analyse responses from 1717 parent-adolescent dyads from the Family Life, Activity, Sun, Health, and Eating study. Main Outcome Measures: Adolescents/parents completed self-reports of their fruit and vegetable consumption, junk food and sugary drinks consumption, engagement in physical activity, and engagement in screen time sedentary behaviours. Results: Parent/adolescent characteristics are associated with each other’s health-relevant intentions/behaviours above the effects of individuals’ own characteristics on their own behaviours. Parent/adolescent characteristics covary with each other’s outcomes with similar strength, but parent characteristics more strongly relate to adolescent intentions, whereas adolescent characteristics more strongly relate to parent behaviours. Conclusions: Parents and adolescents may bidirectionally influence each other’s health intentions/behaviours. This highlights the importance of dyadic models of health behaviour and suggests intervention targets