Migration of breast cancer cells : understanding the roles of volume exclusion and cell-to-cell adhesion

We study MCF-7 breast cancer cell movement in a transwell apparatus. Various experimental conditions lead to a variety of monotone and nonmonotone responses which are difficult to interpret. We anticipate that the experimental results could be caused by cell-to-cell adhesion or volume exclusion. Without any modeling, it is impossible to understand the relative roles played by these two mechanisms. A lattice-based exclusion process random-walk model incorporating agent-to-agent adhesion is applied to the experimental system. Our combined experimental and modeling approach shows that a low value of cell-to-cell adhesion strength provides the best explanation of the experimental data suggesting that volume exclusion plays a more important role than cell-to-cell adhesion. This combined experimental and modeling study gives insight into the cell-level details and design of transwell assays.

Differential roles of the pRb and Arf/p53 pathways in murine naevus and melanoma genesis

We report on a systematic analysis of genotype-specific melanocyte (MC) UVR responses in transgenic mouse melanoma models along with tumour penetrance and comparative histopathology. pRb or p53 pathway mutations cooperated with NrasQ61K to transform MCs. We previously reported that MCs migrate from the follicular outer root sheath into the epidermis after neonatal UVR. Here, we found that Arf or p53 loss markedly diminished this response. Despite this, mice carrying these mutations developed melanoma with very early age of onset after neonatal UVR. Cdk4R24C did not affect the MC migration. Instead, independent of UVR exposure, interfollicular dermal MCs were more prevalent in Cdk4R24C mice. Subsequently, in adulthood, these mutants developed dermal MC proliferations reminiscent of superficial congenital naevi. Two types of melanoma were observed in this model. The location and growth pattern of the first was consistent with derivation from the naevi, while the second appeared to be of deep dermal origin. In animals carrying the Arf or p53 defects, no naevi were detected, with all tumours ostensibly skipping the benign precursor stage in progression.

From social butterfly to engaged citizen: Urban informatics, social media, ubiquitous computing, and mobile technology to support citizen engagement

Web applications such as blogs, wikis, video and photo sharing sites, and social networking systems have been termed ‘Web 2.0’ to highlight an arguably more open, collaborative, personalisable, and therefore more participatory internet experience than what had previously been possible. Giving rise to a culture of participation, an increasing number of these social applications are now available on mobile phones where they take advantage of device-specific features such as sensors, location and context awareness. This international volume of book chapters will make a contribution towards exploring and better understanding the opportunities and challenges provided by tools, interfaces, methods and practices of social and mobile technology that enable participation and engagement. It brings together an international group of academics and practitioners from a diverse range of disciplines such as computing and engineering, social sciences, digital media and human-computer interaction to critically examine a range of applications of social and mobile technology, such as social networking, mobile interaction, wikis, twitter, blogging, virtual worlds, shared displays and urban sceens, and their impact to foster community activism, civic engagement and cultural citizenship.

A two-compartment mechanochemical model of the roles of transforming growth factor-beta and tissue tension in dermal wound healing

The repair of dermal tissue is a complex process of interconnected phenomena, where cellular, chemical and mechanical aspects all play a role, both in an autocrine and in a paracrine fashion. Recent experimental results have shown that transforming growth factor-beta (TGF-beta) and tissue mechanics play roles in regulating cell proliferation, differentiation and the production of extracellular materials. We have developed a 1D mathematical model that considers the interaction between the cellular, chemical and mechanical phenomena, allowing the combination of TGF-beta and tissue stress to inform the activation of fibroblasts to myofibroblasts. Additionally, our model incorporates the observed feature of residual stress by considering the changing zero-stress state in the formulation for effective strain. Using this model, we predict that the continued presence of TGF-beta in dermal wounds will produce contractures due to the persistence of myofibroblasts; in contrast, early elimination of TGF-beta significantly reduces the myofibroblast numbers resulting in an increase in wound size. Similar results were obtained by varying the rate at which fibroblasts differentiate to myofibroblasts and by changing the myofibroblast apoptotic rate. Taken together, the implication is that elevated levels of myofibroblasts is the key factor behind wounds healing with excessive contraction, suggesting that clinical strategies which aim to reduce the myofibroblast density may reduce the appearance of contractures.

From reader to writer : citizen journalism as news produsage

Today, participatory or citizen journalism – journalism which enables readers to become writers – exists online and offline in a variety of forms and formats, operates under a number of editorial schemes, and focusses on a wide range of topics from the specialist to the generic, and the micro-local to the global. Key models in this phenomenon include veteran sites Slashdot and Indymedia, as well as news-related Weblogs; more recent additions into the mix have been the South Korean OhmyNews, which in 2003 was “the most influential online news site in that country, attracting an estimated 2 million readers a day” (Gillmor, 2003a, p. 7), with its new Japanese and international offshoots, as well as the Wikipedia with its highly up-to-date news and current events section and its more recent offshoot Wikinews, and even citizen-produced video news as it is found in sites such as YouTube and Current.tv.

Citizen journalism and everyday life : a case study of Germany's myHeimat.de

The impact of citizen journalism on the established journalism industry, and its role in the future news media mix, remain key topics in current journalism studies research, not least in the context of the current crisis facing many news organisations around the globe. The centrality of this issue is also reflected in the substantial number of ‘citizen journalism’ monographs and collections published across the last few years (see for example Paterson & Domingo, 2008; Boler, 2008; Allan & Thorsen, 2009; Neuberger, Nuernbergk, & Rischke, 2009; Gordon, 2009; Russell & Echchaibi, 2009; Meikle & Redden, forthcoming). With relatively few notable exceptions, much of the research and wider public discussion surrounding the citizen journalism phenomenon has employed a relatively narrow definition of the term, with many researchers focussing on citizen journalism projects which provide mainly political news and commentary, and on their role in influencing the political process especially in countries like the U.S.

News produsage in a pro-am mediasphere : why citizen journalism matters

The rise to prominence of citizen journalism is usually described as a paradigm shift in the relationship between news organizations and their audiences – ‘citizen’ or ‘amateur’ journalists are positioned as inherently different from, and possibly in competition with, ‘professional’ journalists. Some journalists in the industry have taken up this theme, and are at pains to distinguish their professional, supposedly objective and accountable practices from what they describe as the opinionated and partisan ‘armchair journalism’ of amateurs, while some citizen journalists, in turn, give as good at they get and describe the professionals as lackeys of their corporate masters who (willingly or unwittingly) fall prey to political and commercial spin. In fact, the very terminology we use to describe both sides creates the impression that professionals are not also citizens, and that citizen journalists are incapable of having professional skills and knowledges; in reality, of course, the lines between them are much less clear.

G4C2C : enabling citizen engagement at arms' length from government

The recognition that Web 2.0 applications and social media sites will strengthen and improve interaction between governments and citizens has resulted in a global push into new e-democracy or Government 2.0 spaces. These typically follow government-to-citizen (g2c) or citizen-to-citizen (c2c) models, but both these approaches are problematic: g2c is often concerned more with service delivery to citizens as clients, or exists to make a show of ‘listening to the public’ rather than to genuinely source citizen ideas for government policy, while c2c often takes place without direct government participation and therefore cannot ensure that the outcomes of citizen deliberations are accepted into the government policy-making process. Building on recent examples of Australian Government 2.0 initiatives, we suggest a new approach based on government support for citizen-to-citizen engagement, or g4c2c, as a workable compromise, and suggest that public service broadcasters should play a key role in facilitating this model of citizen engagement.

The citizen's voice : Albert Hirschman's Exit, Voice and Loyalty and its contribution to media citizenship debates

This paper analyses Albert Hirschman's Exit, Voice and Loyalty (Hirschman 1970) as a basis for understanding the relationship between media and citizenship. It considers the significance of Hirschman's concept of voice in relation to media policy, media participation through user-created content, and the rise of 'citizen media' and 'citizen journalism'. It associates these developments with a 'de-centering' of both media practice and media studies, as considered by Couldry (2006a, 2006b). It concludes by suggesting that voice and participation, rather than citizenship, may constitute a more suitable foundation for understanding new digital media initiatives.

Citizen consultation from above and below : the Australian perspective

Citizen engagement and e‐government initiatives in Australia remain somewhat underdeveloped, not least for a number of fundamental structural reasons. Fledgling initiatives can be divided into a number of broad categories, including top‐down government consultation through blogs and similar experimental online sites operated by government departments; bottom‐up NGO‐driven watchdog initiatives such as GetUp!’s Project Democracy site, modelled on projects established in the UK; and a variety of more or less successful attempts by politicians (and their media handlers) to utilise social networking tools to connect with constituents while bypassing the mainstream media. This chapter explores these initiatives, and discusses the varying levels of success which they have found to date.

Citizen journalism : a primer :when news takes to the Internet

This paper identifies factors underpinning the emergence of citizen journalism, including the rise of Web 2.0, rethinking journalism as a professional ideology, the decline of ‘high modernist’ journalism, divergence between elite and popular opinion, changing revenue bases for news production, and the decline of deference in democratic societies. It will connect these issues to wider debates about the implications of journalism and news production increasingly going into the Internet environment.