Tensile properties of graphene nanotube hybrid structures : a molecular dynamics study

Graphene has been reported with record-breaking properties which have opened up huge potential applications. A considerable research has been devoted to manipulate or modify the properties of graphene to target a more smart nanoscale device. Graphene and carbon nanotube hybrid structure (GNHS) is one of the promising graphene derivates, while their mechanical properties have been rarely discussed in literature. Therefore, such a studied is conducted in this paper basing on the large-scale molecular dynamics simulation. The target GNHS is constructed by considering two separate graphene layers that being connected by single-wall carbon nanotubes (SWCNTs) according to the experimental observations. It is found that the GNHSs exhibit a much lower yield strength, Young’s modulus, and earlier yielding comparing with a bilayer graphene sheet. Fracture of studied GNHSs is found to fracture located at the connecting region between carbon nanotubes (CNTs) and graphene. After failure, monatomic chains are normally observed at the front of the failure region, and the two graphene layers at the failure region without connecting CNTs will adhere to each other, generating a bilayer graphene sheet scheme (with a layer distance about 3.4 Å). This study will enrich the current understanding of the mechanical performance of GNHS, which will guide the design of GNHS and shed lights on its various applications.

Did socio-ecological factors drive the spatiotemporal patterns of pandemic influenza A (H1N1)?

BACKGROUND Pandemic influenza A (H1N1) has a significant public health impact. This study aimed to examine the effect of socio-ecological factors on the transmission of H1N1 in Brisbane, Australia. METHODOLOGY We obtained data from Queensland Health on numbers of laboratory-confirmed daily H1N1 in Brisbane by statistical local areas (SLA) in 2009. Data on weather and socio-economic index were obtained from the Australian Bureau of Meteorology and the Australian Bureau of Statistics, respectively. A Bayesian spatial conditional autoregressive (CAR) model was used to quantify the relationship between variation of H1N1 and independent factors and to determine its spatiotemporal patterns. RESULTS Our results show that average increase in weekly H1N1 cases were 45.04% (95% credible interval (CrI): 42.63-47.43%) and 23.20% (95% CrI: 16.10-32.67%), for a 1 °C decrease in average weekly maximum temperature at a lag of one week and a 10mm decrease in average weekly rainfall at a lag of one week, respectively. An interactive effect between temperature and rainfall on H1N1 incidence was found (changes: 0.71%; 95% CrI: 0.48-0.98%). The auto-regression term was significantly associated with H1N1 transmission (changes: 2.5%; 95% CrI: 1.39-3.72). No significant association between socio-economic indexes for areas (SEIFA) and H1N1 was observed at SLA level. CONCLUSIONS Our results demonstrate that average weekly temperature at lag of one week and rainfall at lag of one week were substantially associated with H1N1 incidence at a SLA level. The ecological factors seemed to have played an important role in H1N1 transmission cycles in Brisbane, Australia.

Science of winning soccer : emergent pattern-forming dynamics in association football

Quantitative analysis is increasingly being used in team sports to better understand performance in these stylized, delineated, complex social systems. Here we provide a first step toward understanding the pattern-forming dynamics that emerge from collective offensive and defensive behavior in team sports. We propose a novel method of analysis that captures how teams occupy sub-areas of the field as the ball changes location. We used the method to analyze a game of association football (soccer) based upon a hypothesis that local player numerical dominance is key to defensive stability and offensive opportunity. We found that the teams consistently allocated more players than their opponents in sub-areas of play closer to their own goal. This is consistent with a predominantly defensive strategy intended to prevent yielding even a single goal. We also find differences between the two teams' strategies: while both adopted the same distribution of defensive, midfield, and attacking players (a 4:3:3 system of play), one team was significantly more effective both in maintaining defensive and offensive numerical dominance for defensive stability and offensive opportunity. That team indeed won the match with an advantage of one goal (2 to 1) but the analysis shows the advantage in play was more pervasive than the single goal victory would indicate. Our focus on the local dynamics of team collective behavior is distinct from the traditional focus on individual player capability. It supports a broader view in which specific player abilities contribute within the context of the dynamics of multiplayer team coordination and coaching strategy. By applying this complex system analysis to association football, we can understand how players' and teams' strategies result in successful and unsuccessful relationships between teammates and opponents in the area of play.

Competing together : assessing the dynamics of team-team and player-team synchrony in professional association football

This study investigated movement synchronization of players within and between teams during competitive association football performance. Cluster phase analysis was introduced as a method to assess synchronies between whole teams and between individual players with their team as a function of time, ball possession and field direction. Measures of dispersion (SD) and regularity (sample entropy – SampEn – and cross sample entropy – Cross-SampEn) were used to quantify the magnitude and structure of synchrony. Large synergistic relations within each professional team sport collective were observed, particularly in the longitudinal direction of the field (0.89 ± 0.12) compared to the lateral direction (0.73 ± 0.16, p < .01). The coupling between the group measures of the two teams also revealed that changes in the synchrony of each team were intimately related (Cross-SampEn values of 0.02 ± 0.01). Interestingly, ball possession did not influence team synchronization levels. In player–team synchronization, individuals tended to be coordinated under near in-phase modes with team behavior (mean ranges between −7 and 5° of relative phase). The magnitudes of variations were low, but more irregular in time, for the longitudinal (SD: 18 ± 3°; SampEn: 0.07 ± 0.01), compared to the lateral direction (SD: 28 ± 5°; SampEn: 0.06 ± 0.01, p < .05) on-field. Increases in regularity were also observed between the first (SampEn: 0.07 ± 0.01) and second half (SampEn: 0.06 ± 0.01, p < .05) of the observed competitive game. Findings suggest that the method of analysis introduced in the current study may offer a suitable tool for examining team’s synchronization behaviors and the mutual influence of each team’s cohesiveness in competing social collectives.

Reluctantly virtual : modelling copyright industry dynamics

During the evolution of the music industry, developments in the media environment have required music firms to adapt in order to survive. Changes in broadcast radio programming during the 1950s; the Compact Cassette during the 1970s; and the deregulation of media ownership during the 1990s are all examples of changes which have heavily affected the music industry. This study explores similar contemporary dynamics, examines how decision makers in the music industry perceive and make sense of the developments, and reveals how they revise their business strategies, based on their mental models of the media environment. A qualitative system dynamics model is developed in order to support the reasoning brought forward by the study. The model is empirically grounded, but is also based on previous music industry research and a theoretical platform constituted by concepts from evolutionary economics and sociology of culture. The empirical data primarily consist of 36 personal interviews with decision makers in the American, British and Swedish music industrial ecosystems. The study argues that the model which is proposed, more effectively explains contemporary music industry dynamics than music industry models presented by previous research initiatives. Supported by the model, the study is able to show how “new” media outlets make old music business models obsolete and challenge the industry’s traditional power structures. It is no longer possible to expose music at one outlet (usually broadcast radio) in the hope that it will lead to sales of the same music at another (e.g. a compact disc). The study shows that many music industry decision makers still have not embraced the new logic, and have not yet challenged their traditional mental models of the media environment. Rather, they remain focused on preserving the pivotal role held by the CD and other physical distribution technologies. Further, the study shows that while many music firms remain attached to the old models, other firms, primarily music publishers, have accepted the transformation, and have reluctantly recognised the realities of a virtualised environment.

The Use of Ecological Design to Achieve Sustainable Development in Queensland, Australia

This series of technical papers arose out of the action by a private entrepreneur to initiate a process beyond mere regulatory compliance in order to achieve best environmental practice at proposed large new visitor gateways to Australia’s Great Barrier Reef. Because of the complexity of issues involved at such urbanized downstream sites, the range of topics covered is wide – though still only those considered at this juncture to be of management priority. Included on this platform is one introductory paper reviewing the history of environmental management in the field in Queensland, and three papers which seek to appreciate the main techniques by which government contributes to the solutions viz. through the national park, threatened species list, and environmental impact assessment. The history paper was designed to allow the present series to be considered in broad context as well as performance to date. The work emphasizes that much of the fertile land that must be sustained nowadays lies in the province of the private sector, and that the initiative to create any new cost-effective paradigm in ecologically-sustainable practices lies mostly in their hands. In all instances, this strategic approach to large-scale property planning is through ecological design – using field case studies around the immediate biophysical catchment of the development, with attendant focus on the associated legal catchment (the actual development site) and the social catchment (the effective land managers). The first of these has given rise to a document termed a Regional Landscape Strategy, its implementation planned in concert with an Environmental Impact Assessment of the site and with a Strategic Regional Initiative (still being tested in the field) for community engagement. The first document takes into account the aspirations of government as expressed in its broad-scale regional plans.

Introducing dynamics : a new approach to "new media" [Editorial]

The term ‘‘new media’’ has been in play for decades now, and one might be forgiven for wondering how much longer digital forms and platforms can really be called ‘‘new,’’ or even what the scholarship of new media contributes to knowledge. Is it possible to say new things about new media? We think so. This Companion not only demonstrates the variety, salience, and importance of new media studies but also proposes a distinctive approach to the topic : an approach we call ‘‘new media dynamics.’’ In this view, what’s interesting about ‘‘new media’’ is not novelty as such but dynamism. Capitalism, technology, social networks, and media all evolve and change, sometimes to our delight, sometimes our dismay. This incessant process of disruption, renewal, and eventual (if often partial) replacement is now one of humanity’s central experiences. This cutting-edge collection brings together a stellar array of the world’s top researchers, cultural entrepreneurs, and emerging scholars to give the dynamics of new media their first full-length, multidisciplinary, historical, and critical treatment. Across 34 chapters, an international line-up of the very best authors reflects on the historical, technical, cultural, and political changes that underlie the emergence of new media, as existing patterns and assumptions are challenged by the forces of ‘‘creative destruction’’ and innovation, both economic and cultural. At the same time they show that familiar themes and problems carry through from ‘‘old’’media – questions of identity, sexuality, politics, relationships, and meaning.

Agricultural production and the ecological question

Environmental degradation is a worldwide phenomenon. It is manifested in the clearing of forests, polluted waterways, soil erosion, the loss of biodiversity, the presence of chemicals in the ecosystem and a host of other concerns. Modern agricultural practices have been implicated in much of this degradation. This chapter explores the connections between the form of agricultural production undertaken in advanced nations – so called ‘productivist’ or ‘high-tech’ farming – and environmental degradation. It is argued, first, that the entrenchment of productivist agriculture has placed considerable, and continuing, pressures on the environment and, second, that while there are both new options for a more sustainable agriculture and new policies being proposed to tackle the existing problem, the underlying basis of productivist agriculture remains largely unchallenged. The prediction is that environmental degradation will continue unabated until more dramatic (and possibly less palatable) measures are taken to alter the behaviour of producers and the trajectory of farming and grazing industries throughout the world.

Impact of passenger group dynamics on an airport evacuation process using an agent-based model

The safety of passengers is a major concern to airports. In the event of crises, having an effective and efficient evacuation process in place can significantly aid in enhancing passenger safety. Hence, it is necessary for airport operators to have an in-depth understanding of the evacuation process of their airport terminal. Although evacuation models have been used in studying pedestrian behaviour for decades, little research has been done in considering the evacuees’ group dynamics and the complexity of the environment. In this paper, an agent-based model is presented to simulate passenger evacuation process. Different exits were allocated to passengers based on their location and security level. The simulation results show that the evacuation time can be influenced by passenger group dynamics. This model also provides a convenient way to design airport evacuation strategy and examine its efficiency. The model was created using AnyLogic software and its parameters were initialised using recent research data published in the literature.

Ecological design with respect to the environment of large-scale marina developments in Queensland

Ecological principles have been employed to assist in the sustainability of a suite of 'gateway' marinas currently being developed in Queensland. Tasks included (a) location and fostering of core remnant native vegetation areas, (b) understanding the dynamic patterns of region behaviour using the ecological strategies employed by key flora and fauna species, (c) promoting those native wildlife species best characterising the region, and (d) allocating management actions along elongated buffer zones to the catchment headwaters (rather than only peripheral to the property). The design of infrastructure and its relationship to sustainable landscape development is lacking such a response int eh planning and detailing of new marinas. This paper distinguishes between the practice of landscape ecology and the design of ecological landscapes, offering examples of the principles of the latter in support of the concept of ecological landscape practice.

Exploring board dynamics : director participation during board meetings

Despite board meetings representing the main arena where directors discharge their duties and make critical corporate decisions, we know little about what occurs in the boardroom. Consequently, there is increasing academic interest in understanding how meetings are run and how directors participate. This study contributes to this emerging literature by exploring the impact of board meeting arrangements on directors’ interactions and perceptions of meeting effectiveness. We video-taped board meetings at two Australian corporations operating in the same industry and use an in-depth analysis of interactions and board processes to reveal that a rather small difference in meeting arrangements (i.e. the timing and length of meetings) had a significant influence on interaction patterns. Specifically, given significant amounts of environmental turbulence in the sector, director inclusiveness and participation were reduced as time pressure increased due to shorter meetings, lowering director perceptions of meeting effectiveness.

Dynamics of affordances and implications for design

Affordance is an important concept in HCI. There are various interpretations of affordances but it has been difficult to use this concept for design purposes. Often the treatment of affordances in the current HCI literature has been as a one-to-one relationship between a user and an artefact. According to our views, affordance is a dynamic, always emerging relationship between a human and his environment. We believe that the social and cultural contexts within which an artefact is situated affect the way in which the artefact is used. Using a Structuration Theory approach, we argue that affordances need also be treated at a much broader level, encompassing social and cultural aspects. We suggest that affordances should be seen at three levels: single user, organizational (or work group) and societal. Focusing on the organizational level affordances, we provide details of several important factors that affect the emergence of affordances.

Ecological consequences of fragmentation and deforestation in an urban landscape : a case study

Landscape change is an ongoing process even within established urban landscapes. Yet, analyses of fragmentation and deforestation have focused primarily on the conversion of non-urban to urban landscapes in rural landscapes and ignored urban landscapes. To determine the ecological effects of continued urbanization in urban landscapes, tree-covered patches were mapped in the Gwynns Falls watershed (17158.6 ha) in Maryland for 1994 and 1999 to document fragmentation, deforestation, and reforestation. The watershed was divided into lower (urban core), middle (older suburbs), and upper (recent suburbs) subsections. Over the entire watershed a net of 264.5 of 4855.5 ha of tree-covered patches were converted to urban land use-125 new tree-covered patches were added through fragmentation, 4 were added through reforestation, 43 were lost through deforestation, and 7 were combined with an adjacent patch. In addition, 180 patches were reduced in size. In the urban core, deforestation continued with conversion to commercial land use. Because of the lack of vegetation, commercial land uses are problematic for both species conservation and derived ecosystem benefits. In the lower subsection, shape complexity increased for tree-covered patches less than 10 ha. Changes in shape resulted from canopy expansion, planted materials, and reforestation of vacant sites. In the middle and upper subsections, the shape index value for tree-covered patches decreased, indicating simplification. Density analyses of the subsections showed no change with respect to patch densities but pointed out the importance of small patches (≤5 ha) as "stepping stone" to link large patches (e. g., ≥100 ha). Using an urban forest effect model, we estimated, for the entire watershed, total carbon loss and pollution removal, from 1994 to 1999, to be 14,235,889.2 kg and 13,011.4 kg, respectively due to urban land-use conversions.

Molecular dynamics simulation of mechanical behavior of osteopontin-hydroxyapatite interfaces

Bone is characterized with an optimized combination of high stiffness and toughness. The understanding of bone nanomechanics is critical to the development of new artificial biological materials with unique properties. In this work, the mechanical characteristics of the interfaces between osteopontin (OPN, a noncollagenous protein in extrafibrillar protein matrix) and hydroxyapatite (HA, a mineral nanoplatelet in mineralized collagen fibrils) were investigated using molecular dynamics method. We found that the interfacial mechanical behaviour is governed by the electrostatic attraction between acidic amino acid residues in OPN and calcium in HA. Higher energy dissipation is associated with the OPN peptides with a higher number of acidic amino acid residues. When loading in the interface direction, new bonds between some acidic residues and HA surface are formed, resulting in a stick-slip type motion of OPN peptide on the HA surface and high interfacial energy dissipation. The formation of new bonds during loading is considered to be a key mechanism responsible for high fracture resistance observed in bone and other biological materials.