A review of human sensory dynamics for application to models of driver steering and speed control.

In comparison with the high level of knowledge about vehicle dynamics which exists nowadays, the role of the driver in the driver-vehicle system is still relatively poorly understood. A large variety of driver models exist for various applications; however, few of them take account of the driver's sensory dynamics, and those that do are limited in their scope and accuracy. A review of the literature has been carried out to consolidate information from previous studies which may be useful when incorporating human sensory systems into the design of a driver model. This includes information on sensory dynamics, delays, thresholds and integration of multiple sensory stimuli. This review should provide a basis for further study into sensory perception during driving.This work was supported by the UK Engineering and Physical Sciences Research Council (EP/P505445/1) (studentship for Nash).This is the published version. It first appeared from Springer at http://dx.doi.org/10.1007/s00422-016-0682-x

Polybridge Season 3: Ecosystem effects of polychaete-assisted sand filters

This study is an extension of research undertaken in the first two seasons of the Polybridge Project (2013-2016: for results see Palmer et al., 2016), which sought to investigate operational aspects of polychaete-assisted sand filters (PASF) when deployed for scaled prawn farm recirculation at the Bribie Island Research Centre (BIRC). The aims of the present work were to assess its functionality with increased organic loading rates provided by higher prawn stocking densities than previously trialled, and to assess the ecological effects on this integrated farming system when using PASF to initially fill ponds for a range of biosecurity purposes. Using prawn postlarval stocking densities in excess of 44 m-2, prawn production of up to 12 tonnes ha-1 was achieved without discharge of any wastewater during the production season (2015-16). However, the average production for the two ponds was 9.4 tonnes ha-1, which was lower than in the previous season (9.9 tonnes ha-1 in 2014/15) which used a lower prawn stocking density (37.5 postlarvae m-2). The prawns and worms produced were again healthy and of high commercial quality and value, but slower prawn growth (particularly after 140 d) and lower worm survival limited overall production in the fully-recirculated system. There were also several concerning aspects to this closed-system approach that need to be highlighted. Firstly, nutrient levels in the pond waters rose to particularly high levels, and some of the more toxic parameters, such as ammonia, reached critical levels that could be considered dangerous for routine prawn culture operations. Worm production in the PASF beds also suffered from the very rich wastewaters in the integrated system, and the capacity of PASF to filter water via percolation was limited by excessive sand clogging and a build-up of organic matter on the upper surface of the sand beds. The resultant excessive anoxic conditions created in the sand beds appeared to reduce worm productivity which, in turn, reduced their sand cleansing actions, for an overall lower functionality in terms of nutrient (and particularly nitrogen) removal rates. Alternatively, within the confines of the overall study, there were no significant deleterious effects on worm production or nutrient removal efficacies from using the PASF beds to initially fill the prawn production pond. The apparent effect of this on pond plankton communities was: 1) to slow the development of copepod populations; and 2) change the assemblage of algal species in the first few weeks after filling. This slower development of natural feed organisms in the PASF-filled pond may have provided lower survival of the particularly-young (PL 13) prawn seedstock used to stock the pond. Importantly however, there may be several potential remedies to this issue. These include management for a longer period for bloom development after fill and before stocking, and assuming a greater reliance on artificial feeds more suited to small prawns. As expected, this pond-fill strategy appeared to beneficially help exclude some problematic algal species, and greatly reduced barnacle fouling, though tube worm fouling did not appear overly affected. The project successfully demonstrated a third successive season of zero-water discharge from an integrated prawn/ worm production system, though ultimately, the water in ponds with some residual nutrients were discharged. The expansion of prawn farming in Australia is limited by nutrient discharge issues, and biosecurity measures are also of increasing interest to this industry. In this legacy project, polychaete-assisted sand filters are further demonstrated to hold potential for biosecurity controls whilst minimising nutrient discharge

Reverse graded relaxed buffers for high Ge content SiGe virtual substrates

An innovative approach is proposed for epitaxial growth of high Ge content, relaxed Si1−xGex buffer layers on a Si(001) substrate. The advantages of the technique are demonstrated by growing such structures via chemical vapor deposition and their characterization. Relaxed Ge is first grown on the substrate followed by the reverse grading approach to reach a final buffer composition of 0.78. The optimized buffer structure is only 2.8 µm thick and demonstrates a low surface threading dislocation density of 4×106 cm−2, with a surface roughness of 2.6 nm. The buffers demonstrate a relaxation of up to 107%

Interaction specificity between leaf-cutting ants and vertically transmitted Pseudonocardia bacteria

BACKGROUND : The obligate mutualism between fungus-growing ants and microbial symbionts offers excellent opportunities to study the specificity and stability of multi-species interactions. In addition to cultivating fungus gardens, these ants have domesticated actinomycete bacteria to defend gardens against the fungal parasite Escovopsis and possibly other pathogens. Panamanian Acromyrmex echinatior leaf-cutting ants primarily associate with actinomycetes of the genus Pseudonocardia. Colonies are inoculated with one of two vertically transmitted phylotypes (Ps1 or Ps2), and maintain the same phylotype over their lifetime. We performed a cross-fostering experiment to test whether co-adaptations between ants and bacterial phylotypes have evolved, and how this affects bacterial growth and ant prophylactic behavior after infection with Escovopsis. RESULTS : We show that Pseudonocardia readily colonized ants irrespective of their colony of origin, but that the Ps2 phylotype, which was previously shown to be better able to maintain its monocultural integrity after workers became foragers than Ps1, reached a higher final cover when grown on its native host than on alternative hosts. The frequencies of major grooming and weeding behaviors co-varied with symbiont/host combinations, showing that ant behavior also was affected when cuticular actinomycete phylotypes were swapped. CONCLUSION : These results show that the interactions between leaf-cutting ants and Pseudonocardia bear signatures of mutual co-adaptation within a single ant population.http://www.biomedcentral.com/bmcevolbiolhb201

Sperm mixing in the polyandrous leaf-cutting ant Acromyrmex echinatior

The insemination of queens by sperm from multiple males (polyandry) has evolved in a number of eusocial insect lineages despite the likely costs of the behavior. The selective advantages in terms of colony fitness must therefore also be significant and there is now good evidence that polyandry increases genetic variation among workers, thereby improving the efficiency of division of labor, resistance against disease, and diluting the impact of genetically incompatible matings. However, these advantages will only be maximized if the sperm of initially discrete ejaculates are mixed when stored in queen spermathecae and used for egg fertilization in a “fair raffle.” Remarkably, however, very few studies have addressed the level of sperm mixing in social insects. Here we analyzed sperm use over time in the highly polyandrous leaf-cutting ant Acromyrmex echinatior. We genotyped cohorts of workers produced either 2 months apart or up to over a year apart, and batches of eggs laid up to over 2 years apart, and tested whether fluctuations in patriline distributions deviated from random. We show that the representation of father males in both egg and worker cohorts does not change over time, consistent with obligatorily polyandrous queens maximizing their fitness when workers are as genetically diverse as possible

Climate, Conflict and Society: Changing Responses to Weather Extremes in Nineteenth Century Zululand

Changing climates affect human societies differently depending on societal structures, cultural perceptions and their relative vulnerability and resilience. In this study, we explore the complex relationship between climate, conflict and society in nineteenth century Zululand. The paper first reviews current debates surrounding the links between climatic change, societal transformation and the rise of the Zulu Kingdom from the late-eighteenth to early-nineteenth centuries. It then considers new empirical evidence relating to conflict and socio-economic changes at a local scale in Zululand from the early-mid-nineteenth century onwards, using a combination of unpublished archival materials written by missionaries and other observers, together with oral histories and traditions. Our analysis highlights how changing precipitation patterns, especially towards drier conditions, may have contributed to changes in societal responses, including dominant narratives about rain-control, the migration and dissolution of society, and conflicts and unrest. We suggest that temporal differences in these responses were contingent upon the role of leaders, power structures, and the willingness and ability of leaders to yield this power. The case of nineteenth century Zululand exemplifies the complexity of environment-society interactions, and strengthens the call for a thorough scrutiny of the narratives of social unrest in specific socio-cultural contexts

Reconstructing eight decades of genetic variation in an isolated Danish population of the large blue butterfly Maculinea arion

<p>Abstract</p> <p>Background</p> <p>Fragmentation of terrestrial ecosystems has had detrimental effects on metapopulations of habitat specialists. <it>Maculinea </it>butterflies have been particularly affected because of their specialized lifecycles, requiring both specific food-plants and host-ants. However, the interaction between dispersal, effective population size, and long-term genetic erosion of these endangered butterflies remains unknown. Using non-destructive sampling, we investigated the genetic diversity of the last extant population of <it>M. arion </it>in Denmark, which experienced critically low numbers in the 1980s.</p> <p>Results</p> <p>Using nine microsatellite markers, we show that the population is genetically impoverished compared to nearby populations in Sweden, but less so than monitoring programs suggested. Ten additional short repeat microsatellites were used to reconstruct changes in genetic diversity and population structure over the last 77 years from museum specimens. We also tested amplification efficiency in such historical samples as a function of repeat length and sample age. Low population numbers in the 1980s did not affect genetic diversity, but considerable turnover of alleles has characterized this population throughout the time-span of our analysis.</p> <p>Conclusions</p> <p>Our results suggest that <it>M. arion </it>is less sensitive to genetic erosion via population bottlenecks than previously thought, and that managing clusters of high quality habitat may be key for long-term conservation.</p