Hydrogen, single-carbon compounds, and thermal regime in the oceanic ultramafic-dominated lithosphere: insights from a deep borehole on the Atlantis Massif

Water that flows through permeable ultramafic rocks produces high abundances of molecular hydrogen (H2), methane (CH4), and other small organic molecules. Such products can fuel life in the rocky subseafloor, be extracted for energy, and may have played a role in pre-biological chemical synthesis on early Earth or other planetary bodies. The International Ocean Discovery Program drilled a new 1268-m-deep borehole (U1601C) into serpentinized mantle with minor gabbroic rocks on the Atlantis Massif, ∼800-m north of the Lost City hydrothermal field (30°N, Mid-Atlantic Ridge). Measured temperatures of the disturbed borehole reached 91.3 °C, and equilibrated temperatures of the deepest section are estimated to be between 110 – 140 °C. Water collected every ∼ 5-m during drilling operations had H2 concentrations that were regularly > 200 nM and spiked to > 10 µM at multiple depths. In these waters, carbon monoxide was only present in deeper, hotter sections, and potentially associated with gabbroic intrusions into the peridotite host. Open borehole fluids were sampled after drilling and samples recovered from the deepest portion contained elevated short-lived 222-Radon and strontium isotope ratios similar to Lost City fluids, pointing to the presence of in situ subseafloor formation waters that have equilibrated with the host rock. The deepest samples were actively degassing upon recovery and contained 740 ± 360 µM H2, 340 ± 36 µM CH4, and 25.5 µM ∑formate (= formate and formic acid). The shallowest fluids from the open borehole also contain micromolar H2 and ∑formate concentrations, the presence of which cannot be attributed to the upward migration of the deeper, higher concentration fluids. We interpret these data as reflecting two distinct and interconnected regimes of fluid flow and composition. Deep waters that are channelized along faults, lithologic contacts, and other high permeability pathways host high H2 and CH4 concentrations plus micromolar ∑formate that closely mirror the chemistry and isotopic signatures of LCHF vent fluids. Pervasive fluid flow permeates the mesh texture and microfracture network of the serpentinized peridotite and sustains H2 and ∑formate even in the shallowest subseafloor intervals at mild temperatures. These findings demonstrate that both focused and pervasive fluid flow contribute to the transport, and potentially the generation, of reduced volatiles and C1 compounds within the Atlantis Massif

Digital television flexibility: A survey of Australians with disability

Flexibility for many viewers comes from digital technologies and their interaction with television broadcasting. Significantly, as television is switched to digital transmissions, viewers with disability have the potential to experience flexibility in the form of accessibility features such as audio descriptions, captions, lip-reading avatars, signing avatars, spoken subtitles and clean audio. This flexibility may in fact provide some people with access to television for the first time. This exploratory study reports results from an online survey of Australians with disabilities conducted during the final months of the simulcast period before analogue signals were switched off in 2013. While captioning emerged as the most desired accessibility feature, differences surfaced when the data were broken into specific impairment types. This article highlights the importance of digital flexibility specific to impairment type, and locates people with disability as a significant group to consider as more changes take place around digital television broadcasting via the NBN

Television's transition to the Internet: Disability accessibility and broadband-based TV in Australia

Whereas entertainment has featured negatively in the broader NBN debate currently occurring in Australia, within the disability sector it has been recognised as revolutionary. Government, industry and technical analysts describe digital television, particularly that delivered via broadband, as potentially enabling to people with vision and hearing impairments through the more widespread provision of accessibility features such as audio description and closed captions. This article interrogates the approach to accessibility taken by two case studies of broadband-based television: Netflix and catch-up TV. Netflix, which is not officially available in Australia, is often presented as the future of television, while catch-up services provide an example of the current broadband-based television paradigm in this country. Although accessibility features may be available on broadcast television or DVD release, each of these forms of broadband-based television has either previously (Netflix) or currently (catch-up) stripped accessible functions to stream online. The discussion reflects on both activist interventions of people with disability and the industry standards