Design of an angular radial robotic stingray

The propeller is the primary propulsion method for underwater vehicles. It is relatively simple to implement and generally uses rotational motion from the drive through to the propeller. However, it is difficult to seal a high speed propeller shaft from water ingress. As an alternative we can look at nature's own underwater inhabitants and study their locomotive methods.

Integrating multibeam backscatter angular response, mosaic and bathymetry data for benthic habitat mapping

Multibeam echosounders (MBES) are increasingly becoming the tool of choice for marine habitat mapping applications. In turn, the rapid expansion of habitat mapping studies has resulted in a need for automated classification techniques to efficiently map benthic habitats, assess confidence in model outputs, and evaluate the importance of variables driving the patterns observed. The benthic habitat characterisation process often involves the analysis of MBES bathymetry, backscatter mosaic or angular response with observation data providing ground truth. However, studies that make use of the full range of MBES outputs within a single classification process are limited. We present an approach that integrates backscatter angular response with MBES bathymetry, backscatter mosaic and their derivatives in a classification process using a Random Forests (RF) machine-learning algorithm to predict the distribution of benthic biological habitats. This approach includes a method of deriving statistical features from backscatter angular response curves created from MBES data collated within homogeneous regions of a backscatter mosaic. Using the RF algorithm we assess the relative importance of each variable in order to optimise the classification process and simplify models applied. The results showed that the inclusion of the angular response features in the classification process improved the accuracy of the final habitat maps from 88.5% to 93.6%. The RF algorithm identified bathymetry and the angular response mean as the two most important predictors. However, the highest classification rates were only obtained after incorporating additional features derived from bathymetry and the backscatter mosaic. The angular response features were found to be more important to the classification process compared to the backscatter mosaic features. This analysis indicates that integrating angular response information with bathymetry and the backscatter mosaic, along with their derivatives, constitutes an important improvement for studying the distribution of benthic habitats, which is necessary for effective marine spatial planning and resource management.

Ontogeny of long distance migration

The movements of some long-distance migrants are driven by innate compass headings that they follow on their first migrations (e.g., some birds and insects), while the movements of other first-time migrants are learned by following more experienced conspecifics (e.g., baleen whales). However, the overall roles of innate, learned, and social behaviors in driving migration goals in many taxa are poorly understood. To look for evidence of whether migration routes are innate or learned for sea turtles, here for 42 sites around the world we compare the migration routes of >400 satellite-tracked adults of multiple species of sea turtle with ∼45 000 Lagrangian hatchling turtle drift scenarios. In so doing, we show that the migration routes of adult turtles are strongly related to hatchling drift patterns, implying that adult migration goals are learned through their past experiences dispersing with ocean currents. The diverse migration destinations of adults consistently reflected the diversity in sites they would have encountered as drifting hatchlings. Our findings reveal how a simple mechanism, juvenile passive drift, can explain the ontogeny of some of the longest migrations in the animal kingdom and ensure that adults find suitable foraging sites.

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.

Enhancing learning for distance students in an Undergraduate engineering course through real-time web-conferencing

On-line education in engineering has attracted a great deal of interest in recent years. One of the difficulties faced in an on-line engineering program is how to ensure effective communication between lecturers and students, and among the students themselves.Techniques common ten years ago such as email, lecture notes posted to websites, and telephone conversations, are now seen as archaic when compared with opportunities offered by more modern communication technologies, such as real-time web-conferencing.We present our efforts to use the web-conferencing software Elluminate-Live! for delivering tutorials, discussion classes, and even laboratory practicals to groups of students studying engineering off-campus, including students posted overseas. Examples are given from two disciplines. We then compare student feedback across all engineering subjects over the years 2012-2013. Our results show that students welcome web-conferencing as a very effectivemeans to deliver classes to distance students and improve their learning experience.

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.

Engineering Distance Education at Deakin University Australia

Increasing numbers of engineering departments are interested in offering their programs by distanceeducation. These schools grabble with several difficulties and issues associated with distance education:course structure, communication with students, delivery of course material, delivery of exams,accreditation, equity between on-campus and off-campus students, and especially the delivery ofpractical training.In the early 1990’s, Deakin University faced these same problems when it commenced teachingundergraduate engineering by distance education. It now offers a full Bachelor of Engineering degreein both on-campus and off-campus mode, with majors that include civil, mechanical,electrical/electronics, and mechatronics. Student cohorts are approximately 72% on-campus, 28% offcampus.Accredited by Engineers Australia and part of the Washington Accord, Deakin has adapted toadvances in communications technology and changes in education design. The future direction of theSchool includes an emphasis on design-oriented, project-based learning and “flipping the classroom”.As a result, differences between the more traditional off-campus and on-campus cohorts are becomingincreasingly blurred.

The influence of fiber diameter, fabric attributes and environmental conditions on wetness sensations of next-to-skin knitwear

This study investigated the relationships between the sensations of sweaty, damp, muggy and clingy, as assessed by human response from wearer trial garment assessment, and fiber type, fiber, yarn and fabric properties and instrumental fabric measurements of next-to-skin knitwear. Wearer trial assessment of 48 fabrics followed a strict 60 minute protocol including a range of environmental conditions and levels of exercise. Adjusted mean weighted scores were determined using linked garments. Instrumental fabric handle measurements were determined with the Wool HandleMeter (WHM) and Wool ComfortMeter. Data were analyzed using forward stepwise general linear modeling. Mean fiber diameter (MFD) affected the sweaty, damp, muggy and clingy sensation responses accounting for between 23.5% and 56.2% of the variance of these sensations. In all cases, finer fibers were associated with lower sensation scores (preferred). There were also effects of fiber type upon sweaty, muggy and clingy scores, with polyester fiber fabrics having higher scores (less preferred) compared with fabrics composed of wool, particularly for peak sweaty scores in hot and active environments. Attributes such as fabric density, yarn linear density, knitting structure and finishing treatments, but not fabric thickness, accounted for some further variance in these attributes once MFD had been taken into account. This is explained as finer fibers have a greater surface area for any given mass of fiber and so finer fibers can act as a more effective sink for moisture compared with coarser fibers. No fabric handle parameter or other attribute of fiber diameter distribution was significant in affecting these sensation scores.

Long-distance endozoochorous dispersal of submerged macrophyte seeds by migratory waterbirds in northern Europe - a critical review of possibilities and limitations

We review whether migratory Anatidae, i.e., swans, geese and ducks, could be acting as vectors for dispersal of Zostera, Ruppia and Potamogeton propagules by endozoochory (carrying seeds in their guts). We list six prerequisites that must all be fulfilled, if successful dispersal should occur. Several Anatidae species feed on these macrophytes, and undertake rapid long-distance movements, making dispersal possible. We identify four problems, which in combination leads us to conclude that long-distance dispersal events are likely to be rare. (i) Most long-distance movements are out of phase with the reproductive efforts of the plants, and if birds arrive at sites when plants still bear seeds, they are likely to depart well after seed stocks have been depleted. (ii) Seed transport by birds will usually be uni-directional, from north to south on autumn migrations. (iii) Most of the gut contents of migratory birds are likely to have been discarded within 300 km of departure. (iv) In many cases, birds will arrive in habitats seriously different from those they departed, i.e., any seeds carried along will have low chances of surviving in their new site. We suggest that northbound dispersal by endozoochory can only occur during spring if waterbirds feed on seeds that have not been depleted and remained frozen down or buried in sediments, or during moult- or post-moult migrations. Moult migration takes place in summer in phase with the reproductive efforts of the plants. Also epizoochorous dispersal (external attachment) is subject to restrictions i, ii and iv.

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.

Metabolic constraints on long-distance migration in birds

The flight range of migrating birds depends crucially on the amount of fuel stored by the bird prior to migration or taken up en route at stop-over sites. However, an increase in body mass is associated with an increase in energetic costs, counteracting the benefit of fuel stores. Water imbalance, occurring when water loss exceeds metabolic water production, may constitute another less well recognised problem limiting flight range. The main route of water loss during flight is via the lungs; the rate of loss depends on ambient temperature, relative humidity and ventilatory flow and increases with altitude. Metabolite production results in an increased plasma osmolality, also endangering the proper functioning of the organism during flight. Energetic constraints and water-balance problems may interact in determining several aspects of flight behaviour, such as altitude of flight, mode of flight, lap distance and stop-over duration. To circumvent energetic and water-balance problems, a bird could migrate in short hops instead of long leaps if crossing of large ecological barriers can be avoided. However, although necessitating larger fuel stores and being more expensive, migration by long leaps may sometimes be faster than by short hops. Time constraints are also an important factor in explaining why soaring, which conserves energy and water, occurs exclusively in very large species: small birds can soar at low speeds only. Good navigational skills involving accurate orientation and assessment of altitude and air and ground speed assist in avoiding physiological stress during migration.

Energetics of fattening and starvation in the long-distance migratory garden warbler, Sylvia borin, during the migratory phase

Garden warblers (Sylvia borin) were subjected to starvation trials during their autumnal migratory phase in order to simulate a period of non-stop migration. Before, during and after this treatment the energy expenditure, activity, food intake and body mass of the subjects were monitored. Assimilation efficiency was constant throughout the experiments. The catabolized (during starvation) and deposited body tissue (during recovery) consisted of 73% fat. Basal metabolic rate was decreased during the starvation period and tended to a gradual increase during the recovery period. The reduced basal metabolic rate can possibly be attributed to a reduced size/function of the digestive system, which is consistent with the sub-maximal food intake immediately after resuming the supply of food to the experimental birds. The observed reductions in basal metabolic rate during starvation and activity during recovery can be viewed as adaptations contributing to a higher economization of energy supplies. The experimental birds were unable to eat large quantities of food directly after a period of starvation leading to a comparatively low, or no increase in body mass. Such a slow mass increase is in agreement with observations of migratory birds on arrival at stop-over sites.

Effect of electrospinning parameters and polymer concentrations on mechanical-to-electrical energy conversion of randomly-oriented electrospun poly(vinylidene fluoride) nanofiber mats

Poly(vinylidene fluoride) (PVDF) nanofiber mats prepared by an electrospinning technique were used as an active layer for making mechanical-to-electric energy conversion devices. The effects of PVDF concentration and electrospinning parameters (e.g. applied voltage, spinning distance), as well as nanofiber mat thickness on the fiber diameter, PVDF β crystal phase content, and mechanical-to-electrical energy conversion properties of the electrospun PVDF nanofiber mats were examined. It was interesting to find that finer uniform PVDF fibers showed higher β crystal phase content and hence, the energy harvesting devices had higher electrical outputs, regardless of changing the electrospinning parameters and PVDF concentration. The voltage output always changed in the same trend to the change of current output whatever the change trend was caused by the operating parameters or polymer concentration. Both voltage and current output changes followed a similar trend to the change of the β crystal phase content in the nanofibers. The nanofiber mat thickness influenced the device electrical output, and the maximum output was found on the 70 μm thick nanofiber mat. These results suggest that uniform PVDF nanofibers with smaller diameters and high β crystal phase content facilitate mechanical-to-electric energy conversion. The understanding obtained from this study may benefit the development of novel piezoelectric nanofibrous materials and devices for various energy uses.