A new hybrid method for Bayesian network learning With dependency constraints

A Bayes net has qualitative and quantitative aspects: The qualitative aspect is its graphical structure that corresponds to correlations among the variables in the Bayes net. The quantitative aspects are the net parameters. This paper develops a hybrid criterion for learning Bayes net structures that is based on both aspects. We combine model selection criteria measuring data fit with correlation information from statistical tests: Given a sample d, search for a structure G that maximizes score(G, d), over the set of structures G that satisfy the dependencies detected in d. We rely on the statistical test only to accept conditional dependencies, not conditional independencies. We show how to adapt local search algorithms to accommodate the observed dependencies. Simulation studies with GES search and the BDeu/BIC scores provide evidence that the additional dependency information leads to Bayes nets that better fit the target model in distribution and structure.

Caffeine increases sugar-sweetened beverage consumption in a free-living population: a randomised controlled trial

Excessive sugar-sweetened beverage (SSB) consumption has been associated with overweight and obesity. Caffeine is a common additive to SSB, and through dependence effects, it has the potential to promote the consumption of caffeine-containing foods. The objective of the present study was to assess the influence that caffeine has on the consumption of SSB. Participants (n 99) were blindly assigned to either a caffeinated SSB (C-SSB) or a non-caffeinated SSB (NC-SSB) group. Following randomisation, all participants completed a 9 d flavour-conditioning paradigm. They then completed a 28 d ad libitum intake intervention where they consumed as much or as little of C-SSB or NC-SSB as desired. The amount consumed (ml) was recorded daily, 4 d diet diaries were collected and liking of SSB was assessed at the start and end of the intervention. Participants (n 50) consuming the C-SSB had a daily SSB intake of 419 (sd 298) ml (785 (sd 559) kJ/d) over the 28 d intervention, significantly more than participants (n 49) consuming the NC-SSB (273 (sd 278) ml/d, 512 (sd 521) kJ/d) (P< 0·001). A trained flavour panel (n 30) found no difference in flavour between the C-SSB and NC-SSB (P>0·05). However, participants who consumed the C-SSB liked the SSB more than those who consumed the NC-SSB (6·3 v. 6·0 on a nine-point hedonic scale, P= 0·022). The addition of low concentrations of caffeine to the SSB significantly increases the consumption of the SSB. Regulating caffeine as a food additive may be an effective strategy to decrease the consumption of nutrient-poor high-energy foods and beverages.

Real time, perceived time and time online : a review of student experiences of time over thirty years of distance and online education

This paper examines how students use and perceive time when studying in distance education modes and what affects this perception of time and the reality of time. We examine 30 years of student involvement on distance and online education, their comments on both their learning experiences, and the technology requirements of distance education/online learning. Our University has been involved in distance education since its formation in 1974. The online technologies offer increasingly sophisticated and immersive experiences for our students, both on campus and off campus, but many of our students continue to complain of time squeeze, and fail to predict the time it will take them to complete our subjects. We research how the technologies we use for online learning are contributing to this time squeeze perception and the student's "real" time to learn.
Research is drawn from both the Australian Bureau of Statistics and surveys of our students' experiences (we have 32,000 students online, with single online classes of over 1300 students), to examine student use and perceptions of their available time to study and how the technologies used in online learning affect this.

Use of long-distance migration patterns of an endangered species to inform conservation planning for the world's largest marine protected area

Large marine protected areas (MPAs), each hundreds of thousands of square kilometers, have been set up by governments around the world over the last decade as part of efforts to reduce ocean biodiversity declines, yet their efficacy is hotly debated. The Chagos Archipelago MPA (640,000 km2) (Indian Ocean) lies at the heart of this debate. We conducted the first satellite tracking of a migratory species, the green turtle (Chelonia mydas), within the MPA and assessed the species' use of protected versus unprotected areas. We developed an approach to estimate length of residence within the MPA that may have utility across migratory taxa including tuna and sharks. We recorded the longest ever published migration for an adult cheloniid turtle (3979 km). Seven of 8 tracked individuals migrated to distant foraging grounds, often ≥1000 km outside the MPA. One turtle traveled to foraging grounds within the MPA. Thus, networks of small MPAs, developed synergistically with larger MPAs, may increase the amount of time migrating species spend within protected areas. The MPA will protect turtles during the breeding season and will protect some turtles on their foraging grounds within the MPA and others during the first part of their long-distance postbreeding oceanic migrations. International cooperation will be needed to develop the network of small MPAs needed to supplement the Chagos Archipelago MPA.

Seagrass viviparous propagules as a potential long-distance dispersal mechanism

Resilience of seagrass meadows relies on the ability of seagrass to successfully recolonise denuded areas or disperse to new areas. While seed germination and rhizome extension have been explored as modes of recovery and expansion, the contribution of seagrass viviparous propagules to meadow population dynamics has received little attention. Here, we investigated the potential of seagrass viviparous propagules to act as dispersal vectors. We performed a series of density surveys, and in situ and mesocosm-based experiments in Port Phillip Bay, VIC, Australia, using Zostera nigricaulis, a species known to produce viviparous propagules. Production of viviparous propagules was higher at sites with high wind and current exposure, compared to more sheltered environments. A number of propagules remained buoyant and healthy for more than 85 days, suggesting the capacity for relatively long-distance dispersal. Transplanted propagules were found to have improved survivorship within seagrass habitats compared to bare sediment over the short term (4 weeks); however, all propagules suffered longer-term (<100 days) mortality in field experiments. Conditions outside of meadows, including sediment scouring, reduced the likelihood of successful colonisation in bare sediment. Furthermore, sediment characteristics within meadows, such as a smaller grain size and high organic content, positively influenced propagule establishment. This research provides preliminary evidence that propagules have the potential to act as an important long-distance dispersal vector, a process that has previously gone unrecognised. Even though successful establishment of propagules may be rare, viviparous propagules show great potential for seagrass populations given they are facing global decline. © 2014 Coastal and Estuarine Research Federation.

Composition of fuel stores and digestive limitations to fuel deposition rate in the long-distance migratory thrush nightingale, Luscinia luscinia

During their autumn migratory phase, thrush nightingales (Luscinia luscinia) previously starved for 2 d were allowed to refuel under three different ambient temperature conditions (-7 degrees, 7 degrees, and 22 degrees C). During the refueling period, as well as during the preceding control and starvation periods, food intake, body mass, and feces production were monitored. In addition, daily energy expenditure was measured during the refueling period. The compilation of the energy balance during the refueling period revealed an energy density of the deposited tissue of 33.6 kJ g-1. Assuming that the deposited tissue consists of fat and protein exclusively, with energy densities of 39.6 and 5.5 kJ g-1 wet mass, respectively, we estimated the deposited tissue to consist of 82% fat and 18% wet protein (6% dry protein and 12% water). Nitrogen balances during control, starvation, and refueling phases and during a period of prolonged and complete starvation indicated that 5% of the nutrient stores consisted of dry protein. Our results support recent findings that nutrient stores for migration often contain protein in addition to fat and consequently are 15%-25% less energy rich than pure fat stores. These proteins might be stored as muscle or other functional tissue and may be required to support the extra mass of the stores and/or reflect an incapacity of the metabolic machinery to catabolize far exclusively. Fuel deposition rate was positively related with ambient temperature, whereas food intake rate was unaffected by temperature. These results indicate that the rate of fuel deposition is limited by a ceiling in food intake rate; when this ceiling is reached, fuel deposition rate is negatively affected by daily energy expenditure rate. To a certain extent, the ceiling in food intake rate varies depending on feeding conditions over the previous days. These variations in food intake capacity probably reflect the building and breakdown of gut tissues and/or gut enzyme systems and might be insensible and not evolutionary adaptive. Significant energetic costs, however, are probably associated with the maintenance of gut tissues. It is therefore feasible that changes in digestive capacity are regulated and are directed at energy economization.

Online distance education models and research implications

As a form of education, distance education is influenced by educationaltheories and ideologies. Hence, over time its various theoretical modelshave reflected varying emphases on students, both individually and ingroups, on content and process, and on administration and costs, and itsguiding philosophies have ranged from knowledge replication to knowledge creation, and from teacher direction to learner engagement. Its founding purpose was the provision of education to populations who were not able to access available residential education. The reasons were not only based on the individual situation, such as, geographic location, family commitments,work commitments, or cost factors, but also included state issues such as insufficient institutions or a lack of enrolment places, full-time funding, or sufficient staff. These factors have contributed in various ways to the growth of distance education, both historically as when distance education was a major focus in many European countries after WWII, and as a current imperative in many countries where the need and desire for education outstrips the supply through residential institutions, regardless of their fiscal capacities. Education is seen by both individuals and states as essential for the development of a better socio-economic environment, hence, distance education has become the cost-affordable means of provision for millions worldwide.Distance education, then, is framed within larger socio-economic andpolitical contexts. These are not only reflective of societal characteristics like those identified by Keegan (2000): immediacy, globalization, privatization, and industrialization, to which we added professional learning, but also reflective of current social, political, and economic circumstances, such as the sequence of global economic crises this century.Within these contexts then, the provision of distance education seldomarises from the desire of an institution alone; rather there are likely to becomplex national, local, and individual aspirations where distance education is seen as the best solution. The realization of this provision depends on the issues being addressed and the various influences on the particular configuration of design and provision. It may be publicly or privately funded; it may seek to emulate or extend educational provision in residential institutions; its focus may be on increasing access or openness or convenience.Models or designs for distance education, then, have generally arisen from consideration of these instances, in part to provide a framework for researchers and in part to provide a means to reflect on issues that the models themselves have tried to resolve and sometimes inadvertently create.