Temporal dynamics of rod and cone photoreceptor interactions under mesopic illumination

Purpose: Photoreceptor interactions reduce the temporal bandwidth of the visual system under mesopic illumination. The dynamics of these interactions are not clear. This study investigated cone-cone and rod-cone interactions when the rod (R) and three cone (L, M, S) photoreceptor classes contribute to vision via shared post-receptoral pathways. Methods: A four-primary photostimulator independently controlled photoreceptor activity in human observers. To determine the temporal dynamics of receptoral (L, S, R) and post-receptoral (LMS, LMSR, +L-M) pathways (5 Td, 7° eccentricity) in Experiment 1, ON-pathway sensitivity was assayed with an incremental probe (25ms) presented relative to onset of an incremental sawtooth conditioning pulse (1000ms). To define the post-receptoral pathways mediating the rod stimulus, Experiment 2 matched the color appearance of increased rod activation (30% contrast, 25-1000ms; constant cone excitation) with cone stimuli (variable L+M, L/L+M, S/L+M; constant rod excitation). Results: Cone-cone interactions with luminance stimuli (LMS, LMSR, L-cone) reduced Weber contrast sensitivity by 13% and the time course of adaptation was 23.7±1ms (μ±SE). With chromatic stimuli (+L-M, S), cone pathway sensitivity was also reduced and recovery was slower (+L-M 8%, 2.9±0.1ms; S 38%, 1.5±0.3ms). Threshold patterns at ON-conditioning pulse onset were monophasic for luminance and biphasic for chromatic stimuli. Rod-rod interactions increased sensitivity(19%) with a recovery time of 0.7±0.2ms. Compared to cone-cone interactions, rod-cone interactions with luminance stimuli reduced sensitivity to a lesser degree (5%) with faster recovery (42.9±0.7ms). Rod-cone interactions were absent with chromatic stimuli. Experiment 2 showed that rod activation generated luminance (L+M) signals at all durations, and chromatic signals (L/L+M, S/L+M) for durations >75ms. Conclusions: Temporal dynamics of cone-cone interactions are consistent with contrast sensitivity loss in the MC pathway for luminance stimuli and chromatically opponent responses in the PC and KC pathway with chromatic stimuli. Rod-cone interactions limit contrast sensitivity loss during dynamic illumination changes and increase the speed of mesopic light adaptation. The change in relative weighting of the temporal rod signal within the major post-receptoral pathways modifies the sensitivity and dynamics of photoreceptor interactions.

Molecular dynamics investigation on edge stress and shape transition in graphene nanoribbons

Graphene nanoribbon (GNR) with free edges demonstrates unique pre-existing edge energy and edge stress, leading to non-flat morphologies. Using molecular dynamics (MD) methods, we evaluated edge energies as well as edge stresses for four different edge types, including regular edges (armchair and zigzag), armchair edge terminated with hydrogen and reconstructed armchair. The results showed that compressive stress exists in the regular and hydrogen-terminated edges along the edge direction. In contrast, the reconstructed armchair edge is generally subject to tension. Furthermore, we also investigated shape transition between flat and rippled configurations of GNRs with different free edges. It was found that the pre-existing stress at free edges can greatly influence the initial energy state and the shape transition.

Business research in virtual worlds : possibilities and practicalities

Purpose – It is predicted that virtual business and related research possibilities will expand significantly. In this context, the aim of this paper is to use insights from a virtual research project to present a theoretically-informed toolbox of practical suggestions to guide the conduct of virtual world business research. Design/methodology/approach – Archival evidence is presented, and data from a study conducted in Second Lifew in 2007 is interpreted through Llewellyn’s framework (physical, structural, agential, cultural and mental dimensions). Findings – With the burgeoning of virtual business applications, appropriate systems that encompass the dynamics of both the real and the virtual will need to be developed by and for accountants, auditors and business professionals. Researchers of virtual business activities will need to adapt to the physical, structural, agential, cultural and mental dimensions unique to virtual worlds. Research limitations/implications – While based on reflections from a single study in Second Life, this paper identifies possibilities for future virtual research on issues of accountability and accounting relating to virtual worlds. Practical implications – The practical toolbox will assist virtual researchers to deal with the possibilities and practicalities of conducting research in virtual worlds. Originality/value – Despite the proliferation of virtual worlds, predictions of virtual business applications, and consequent accountability and accounting implications, there is a paucity of academic literature on conducting business research in virtual settings. This prescient paper develops a conceptual framework to guide the conduct of research in virtual worlds, and identifies the unique opportunities and challenges they present.

Timing and emplacement dynamics of newly recognised mass flow deposits at ~ 8–12 ka offshore Soufrière Hills volcano, Montserrat : how submarine stratigraphy can complement subaerial eruption histories

This contribution describes two mass movement deposits (total volume ~0.5 km3) identified in seven marine cores located 8 to 15 km offshore southern Montserrat, West Indies. The deposits were emplaced in the last 35 ka and have not previously been recognised in either the subaerial or distal submarine records. Age constraints, provided by radiocarbon dating, show that an explosive volcanic eruption occurred at ca 8–12 ka, emplacing a primary eruption-related deposit that overlies a large (~0.3 km3) reworked bioclastic and volcaniclastic flow deposit, formed from a shelf collapse between 8 and 35 ka. The origin of these deposits has been deduced through the correlation of marine sediment cores, component analysis and geochemical analysis. The 8–12 ka primary volcanic deposit was likely derived from a highly-erosive pyroclastic flow from the Soufrière Hills volcano that entered the ocean and mixed with the water column forming a water-supported density current. Previous investigations of the eruption record suggested that there was a hiatus in activity at the Soufrière Hills volcano between 16 and 6 ka. The ca 8–12 ka eruptive episode identified here shows that this hiatus was shorter than previously hypothesised, and thus highlights the importance of obtaining an accurate and completemarine record of events offshore from volcanic islands and incorporating such data into eruption history reconstructions. Comparisons with the submarine deposit characteristics of the 2003 dome collapse also suggests that the ~8–12 ka eruptive episode was more explosive than eruptions from the current eruptive episode.

Principles of motor learning in ecological dynamics : a comment on functions of learning and the acquisition of motor skills (with reference to sport)

This paper provides a commentary on the contribution by Dr Chow who questioned whether the functions of learning are general across all categories of tasks or whether there are some task-particular aspects to the functions of learning in relation to task type. Specifically, they queried whether principles and practice for the acquisition of sport skills are different than what they are for musical, industrial, military and human factors skills. In this commentary we argue that ecological dynamics contains general principles of motor learning that can be instantiated in specific performance contexts to underpin learning design. In this proposal, we highlight the importance of conducting skill acquisition research in sport, rather than relying on empirical outcomes of research from a variety of different performance contexts. Here we discuss how task constraints of different performance contexts (sport, industry, military, music) provide different specific information sources that individuals use to couple their actions when performing and acquiring skills. We conclude by suggesting that his relationship between performance task constraints and learning processes might help explain the traditional emphasis on performance curves and performance outcomes to infer motor learning.

The role of representative design in talent development : a comment on “Talent identification and promotion programmes of Olympic athletes”

A recent comment in the Journal of Sports Sciences (MacNamara & Collins, 2011) highlighted some major concerns with the current structure of talent identification and development (TID) programmes of Olympic athletes (e.g. Gulbin, 2008; Vaeyens, Gullich, Warr, & Philippaerts, 2009). In a cogent commentary, MacNamara and Collins (2011) provided a short review of the extant literature, which was both timely and insightful. Specifically, they criticised the ubiquitous one-dimensional ‘physically-biased’ attempts to produce world class performers, emphasising the need to consider a number of key environmental variables in a more multi-disciplinary perspective. They also lamented the wastage of talent, and alluded to the operational and opportunistic nature of current talent transfer programmes. A particularly compelling aspect of the comment was their allusion to high profile athletes who had ‘failed’ performance evaluation tests and then proceeded to succeed in that sport. This issue identifies a problem with current protocols for evaluating performance and is a line of research that is sorely needed in the area of talent development. To understand the nature of talent wastage that might be occurring in high performance programmes in sport, future empirical work should seek to follow the career paths of ‘successful’ and ‘unsuccessful’ products of TID programmes, in comparative analyses. Pertinent to the insights of MacNamara and Collins (2011), it remains clear that a number of questions have not received enough attention from sport scientists interested in talent development, including: (i) why is there so much wastage of talent in such programmes? And (ii), why are there so few reported examples of successful talent transfer programmes? These questions highlight critical areas for future investigation. The aim of this short correspondence is to discuss these and other issues researchers and practitioners might consider, and to propose how an ecological dynamics underpinning to such investigations may help the development of existing protocols...

Whom to group with - a Bourdieusian narrative analysis of international students in an Australian university

Introduction to the topic or context and/or mapping of the literature Increasing degree-seeking, self-funded, international students from affluent Asian countries, who use English as an additional language (EAL), have contributed to cultural and linguistic diversities in Australian universities. Such diversities further posed challenges in pedagogy and assessment. In particular, these students' English proficiency and cultural attributes were highlighted as factors in productive group discussions, and equitable group assessment. The focus in the research literature thus far is on how EAL international students can better English proficiency and adaptability to group participation. However, little is known from sociological perspectives about the power relations involved in EAL students' choice of group members in group discussions.

Algorithm for queue estimation with loop detector of time occupancy in off-ramps on signalized motorways

Long traffic queues on off-ramps significantly compromise the safety and throughput of motorways. Obtaining accurate queue information is crucial for countermeasure strategies. However, it is challenging to estimate traffic queues with locally installed inductive loop detectors. This paper deals with the problem of queue estimation with the interpretation of queuing dynamics and the corresponding time-occupancy distribution over motorway off-ramps. A novel algorithm for real-time queue estimation with two detectors is presented and discussed. Results derived from microscopic traffic simulation validated the effectiveness of the algorithm and revealed some of its useful features: (a) long and intermediate traffic queues could be accurately measured, (b) relatively simple detector input (i.e., time occupancy) was required, and (c) the estimation philosophy was independent with signal timing changes and provided the potential to cooperate with advanced strategies for signal control. Some issues concerning field implementation are also discussed.

The emerging role of the Board of Directors in enterprise business technology governance

In an increasingly business technology (BT) dependent world, the impact of the extraordinary changes brought about by the nexus of mobile and cloud technologies, social media and big data is increasingly being felt in the board room. As leaders of enterprises of every type and size, board directors can no longer afford to ignore, delegate or avoid BT-related decisions. Competitive, financial and reputational risk is increased if boards fail to recognize their role in governing technology as an asset and in removing barriers to improving enterprise business technology governance (EBTG). Directors’ awareness of the need for EBTG is increasing. However, industry research shows that board level willingness to rectify the gap between awareness and action is very low or non-existent. This literature review-based research identifies barriers to EBTG effectiveness. It provides a practical starting point for board analysis. We offer four outcomes that boards might focus on to ensure the organizations they govern are not left behind by those led by the upcoming new breed of technology-savvy leaders. Most extant research looks backward for examples, examining data pre-2010, the time when a tipping point in the personal and business use of multimedia and mobile-internet devices significantly deepened the impacts of the identified nexus technology forces, and began rapidly changing the way many businesses engage with their customers, employees and stakeholders. We situate our work amidst these nexus forces, discuss the board’s role in EBTG in this context, and modernize current definitions of enterprise technology governance. The primary limitation faced is the lack of scholarly research relating to EBTG in the rapidly changing digital economy. Although we have used recent (2011 - 2013) industry surveys, the volume of these surveys and congruence across them is significant in terms of levels of increased awareness and calls for increased board attention and competency in EBTG and strategic information use. Where possible we have used scholarly research to illustrate or discuss industry findings.

What are the health needs, familial and social problems of Thai migrants in a local community in Australia? A focus group study

This study explored the health needs, familial and social problems of Thai migrants in a local community in Brisbane, Australia. Five focus groups with Thai migrants were conducted. The qualitative data were examined using thematic content analysis that is specifically designed for focus group analysis. Four themes were identified: (1) positive experiences in Australia, (2) physical health problems, (3) mental health problems, and (4) familial and social health problems. This study revealed key health needs related to chronic disease and mental health, major barriers to health service use, such as language skills, and facilitating factors, such as the Thai Temple. We concluded that because the health needs, familial and social problems of Thai migrants were complex and culture bound, the development of health and community services for Thai migrants needs to take account of the ways in which Thai culture both negatively impacts health and offer positive solutions to problems.

Molecular dynamics simulation of fracture strength and morphology of defective graphene

Different types of defects can be introduced into graphene during material synthesis, and significantly influence the properties of graphene. In this work, we investigated the effects of structural defects, edge functionalisation and reconstruction on the fracture strength and morphology of graphene by molecular dynamics simulations. The minimum energy path analysis was conducted to investigate the formation of Stone-Wales defects. We also employed out-of-plane perturbation and energy minimization principle to study the possi-ble morphology of graphene nanoribbons with edge-termination. Our numerical results show that the fracture strength of graphene is dependent on defects and environmental temperature. However, pre-existing defects may be healed, resulting in strength recovery. Edge functionalization can induce compressive stress and ripples in the edge areas of gra-phene nanoribbons. On the other hand, edge reconstruction contributed to the tensile stress and curved shape in the graphene nanoribbons.

An informal community of practice : the case of the DEHub Virtual Worlds Working Group

The DEHub Virtual Worlds Working Group has an informal membership of nearly 200 members with an interest in education and virtual worlds within the Australian and New Zealand context. Members come from a variety of academic disciplines and may be teaching or research academics, Research Higher Degree candidates, project managers, virtual world builders and developers. The group acts as an informal Community of Practice, facilitating learning and the transfer of skills through social contact, opportunities to collaborate on projects and publications, and through the sharing of knowledge and experience. This poster provides a snapshot of the activity of this highly active group.

Board age and gender diversity : a test of competing linear and curvilinear predictions

We test competing linear and curvilinear predictions between board diversity and performance. The predictions were tested using archival data on 288 organizations listed on the Australian Securities Exchange. The findings provide additional evidence on the business case for board gender diversity and refine the business case for board age diversity.

Numerical Characterization of Nanowires

In this chapter, we will present a contemporary review of the hitherto numerical characterization of nanowires (NWs). The bulk of the research reported in the literatures concern metallic NWs including Al, Cu, Au, Ag, Ni, and their alloys NWs. Research has also been reported for the investigation of some nonmetallic NWs, such as ZnO, GaN, SiC, SiO2. A plenty of researches have been conducted regarding the numerical investigation of NWs. Issues analyzed include structural changes under different loading situations, the formation and propagation of dislocations, and the effect of the magnitude of applied loading on deformation mechanics. Efforts have also been made to correlate simulation results with experimental measurements. However, direct comparisons are difficult since most simulations are carried out under conditions of extremely high strain/loading rates and small simulation samples due to computational limitations. Despite of the immense numerical studies of NWs, a significant work still lies ahead in terms of problem formulation, interpretation of results, identification and delineation of deformation mechanisms, and constitutive characterization of behavior. In this chapter, we present an introduction of the commonly adopted experimental and numerical approaches in studies of the deformation of NWs in Section 1. An overview of findings concerning perfect NWs under different loading situations, such as tension, compression, torsion, and bending are presented in Section 2. In Section 3, we will detail some recent results from the authors’ own work with an emphasis on the study of influences from different pre-existing defect on NWs. Some thoughts on future directions of the computational mechanics of NWs together with Conclusions will be given in the last section.

A critical assessment of the Australian OHS accreditation system's "Body of Knowledge (BoK)"

In response to an increasing perception of poor OHS consultancy quality amongst the Australian public, regulator and OHS professionals, the Safety Institute Australia (SIA) was tasked by the Victorian government to establish an accreditation process for OHS professionals. The OHS accreditation board decided to base its accreditation on a core "body of knowledge" (BoK), against which applicants are assesssed. While the foundation and structure of the BoK is unclear, the BoK consists of a collection of essays from a variety of invited authors. The BoK comprises about 811 pages in 34 chapters, with significant redundancy and considerable subjective components. The SIA BoK is benchmarked against two international best-practices, the German "Core Definition, Object Catalog and Research Domains of Labour Science (Ergonomics)" (Luzcak, Volpert, Raeithel & Schwier, 1989)(100 pages) and the American "Core Competency Model" for the "Master's Degree in Public Health" (Association of Schools of Public Health, 2006) (21 pages). Both "core definition" and "core competency model" are on a comparative level to the BoK. While the German expert panel consisted of 14 eminent professors, the American panel consisted of 135 members, organized in 6 groups chaired by discipline leading academics. The Australian approach employed a broad approach, where 137 professionals, consultants, emerging academics and academics contributed to 8 workshops. Both the German and the American panels maintained an open communication amongst members and with the discipline community throughout the process, whereas SIA applied an open and directed peer-review process. Moreover, the German process involved an analysis of all congress content and journal publications in the scientific domain in a set timeframe, which were then systematically clustered. These results were further expanded by structured interviews with 38 professors in the discpline, grasping their research and teaching practice. The American workgroup however assumed core scientific areas, underlying the domain. Based upon the a-priori assumption, they then established well defined competencies across all areas using a modified Delphi process. Although the BoK attempts to explore the knowledge in the OHS domain without an imposed structure in a bottom-up approach, it does not result in a structured systematic of the science. We conclude that the outcome of the German, rigorous academic approach, and the US American democratic approach under unambiguous academic leadership both outperform the Australian advocacy group approach. This product was determined for both structure and content of the taxonomy delivered through the processes.