VandenBerg, Alfons H.M., November 2017. Fragmentation as a novel propagation strategy in an Early Ordovician graptolite. Alcheringa 42, 1–9. ISSN 0311-5518.
Catenagraptus communalis gen. nov. sp. nov. is a late Floian (Early Ordovician) graptolite from Victoria, Australia, only found as fragments, with each fragment resembling an assemblage of uniserial tubarium-like structures (pseudotubaria) connected by threads (aulons). Individual pseudotubaria consist of a fallosicula and a stipe, both of which are linked by aulons to other pseudotubaria. Adjacent pseudotubaria are in a parent–offspring relationship. Aulons can be generated from both the proximal and distal extremities of fallosiculae, and from the ends of stipes. The aulons are interpreted to have been grown by the zooid that occupied either the fallosicula or the terminal theca of the stipe. Aulons were pathways for a zooid that built a fallosicula at the end of the aulon. This process was repeated to form the assemblage. None of the assemblages contain a true sicula, which suggests that the assemblages present evidence of a new, asexual propagation strategy that involved fragmentation and dispersal. As this interpretation is radical, other models explored are partial sclerotization and modified sicular spines.
The initiation of hydraulic fractures during fluid injection in deep formations can be either engineered or induced unintentionally. Upon injection of CO2, the pore fluids in deep formations can be changed from oil/saline water to CO2 or CO2 dominated. The type of fluid is important not only because the fluid must fracture the rock, but also because rocks saturated with different pore fluids behave differently. We investigated the influence of fluid properties on fracture propagation behavior by using the cohesive zone model in conjunction with a poroelasticity model. Simulation results indicate that the pore pressure fields are very different for different pore fluids even when the initial field conditions and injection schemes (rate and time) are kept the same. Low viscosity fluids with properties of supercritical CO2 will create relatively thin and much shorter fractures in comparison with fluids exhibiting properties of water under similar injection schemes. Two significant times are recognized during fracture propagation: the time at which a crack ceases opening and the later time point at which a crack ceases propagating. These times are very different for different fluids. Both fluid compressibility and viscosity influence fracture propagation, with viscosity being the more important property. Viscosity can greatly affect hydraulic conductivity and the leak‐off coefficient. This analysis assumes the in‐situ pore fluid and injected fluid are the same and the pore space is 100% saturated by that fluid at the beginning of the simulation. 相似文献
Much scholarly work on the literary culture of the early Qing dynasty has focused on notions of memory, trauma, and nostalgia. In contrast, this essay investigates the "contemporary operas" (shishi xiqu) of the seventeenth-century Suzhou playwright Li Yu to argue for the importance of the notion of"the present day." How is this notion of the present day given dramatic form in Li Yu's operas and what implications does this interest in the contemporary have for the broader cultural scene of the early Qing dynasty? This paper will answer these questions by investigating one dramatic technique favored by Li Yu: the inclusion of snippets of rumor and "news" reports into the play. By including such contemporary media reports, Li Yu not only generates a constantly evolving sense of the present, he also projects this sense of immediacy beyond the fiction of the stage into the "reality" of the audience, creating a form of opera eminently suited for both reflecting and producing local Suzhou activism, as evidenced in Li Yu's most famous work, Qing zhong pu (Registers of the pure and loyal), a work chronicling the popular Suzhou protests of the mid-1620s and Wanli yuan (Reunion over ten thousand miles), which stages the dissolution and reintegration of family and empire right after the fall of the Ming. 相似文献
Tuvalu, a place whose image in the ‘West’ is as a small island state, insignificant and remote on the world stage, is becoming remarkably prominent in connection with the contemporary issue of climate change‐related sea‐level rise. My aim in this paper is to advance understanding of the linkages between climate change and island places, by exploring the discursive negotiation of the identity of geographically distant islands and island peoples in the Australian news media. Specifically, I use discourse analytic methods to critically explore how, and to what effects, various representations of the Tuvaluan islands and people in an Australian broadsheet, the Sydney Morning Herald, emphasize difference between Australia and Tuvalu. My hypothesis is that implicating climate change in the identity of people and place can constitute Tuvaluans as .tragic victims. of environmental displacement, marginalizing discourses of adaptation for Tuvaluans and other inhabitants of low‐lying islands, and silencing alternative constructions of Tuvaluan identity that could emphasize resilience and resourcefulness. By drawing attention to the problematic ways that island identities are constituted in climate change discourse in the news media, I advocate a more critical approach to the production and consumption of representations of climate change. 相似文献