164 research outputs found
On the Benthic Invertebrate Megafauna at the Mid-Atlantic Ridge, in the Vicinity of the Charlie-Gibbs Fracture Zone
No full textLittle is known about the fauna that inhabits non-chemosynthetic environments associated with mid-ocean ridges. This thesis investigates a ridge and fracture zone system to assess its influence as a barrier to faunal dispersal, and as a unique bathyal habitat. It also describes the ecology of megabenthic communities inhabiting a ridge. Sites were chosen on the Mid-Atlantic Ridge in the vicinity of the Charlie-Gibbs Fracture Zone, at a target depth of 2,500 m. Four superstations were chosen north and south of the Fracture Zone, on either side of the ridge. Different productivity levels and hydrographic features were characteristic for the northern and southern sites. In order to characterise the benthic megafauna 50 ha were trawled and 32,000 m2 of seafloor were sampled with HD video footage, targeting both flat and 10 ? sloped habitats. Holothurians were the most abundant megafauna. In order to assess their evolutionary relationship 43 holothurian specimens were genetically studied by modelling five of their genes (16S, 18S, 28S, COI, H3) in a phylogenetic analysis. All four sites exhibited noticeably different faunal characteristics. The biomass was highest at the SE, and lowest at the NW site. Body sizes differed between sites for most taxa, that were sufficient in numbers to be compared between sites, most likely as a result of different adaptations to food supply. Differences in species richness were observed between the sampling methods, with the highest richness at the SE site in trawl samples, and highest at the NW and SW sites in the video survey. Species densities were highest at the northern sites with both methods. Differences in diversity were also observed, with trawl samples providing a higher taxonomic resolution than the video survey and showing highest diversity at the SE site and lowest at the NE site. Community composition was significantly different between sites. Variations in the composition of megabenthic assemblages were observed between flat and 10 ? sloped habitats, although the effect of slope appears to be site dependent. The genetic analyses revealed a close relationship between individuals from different families. The extent to which the Ridge acts as a faunal barrier was unclear as the southern sites lacked an obvious difference in community composition. Faunal differences to the north and south of the Fracture Zone, however, suggest that this feature is a barrier to dispersal. The contrasting megafaunal assemblages of the sites probably reflect a combination of environmental drivers including sediment type, phytodetrital quality, hydrography, and habitat complexity
The archangel fragment and C. S. Lewis’s world-building project
No full textIn this article, we argue that, from a few hints in the Bodleian archive and elsewhere, we have discovered C. S. Lewis’s singular attempt at an Archangelic sequel to The Screwtape Letters. By analyzing this small fragment and its contextual clues, we can hear the heaven-scented voice of this anti-Screwtape world. Through this discovery we can unlock hidden links among Lewis’s fiction project of the late 1930s and early 1940s and the ways he created the speculative worlds of those stories, including a spirit of playfulness and discovery, themes critical to his theological perspective, and potential links that draw his 1937–1945 work together into a cohesive whole. Finally, considering this fragment provides an opportunity to test the Lewis Handwriting Chart and open possibilities for further archival research
Canyons, deltas and plains: towards a unified sculptural model of location-based hypertext
No full textWith the growing ubiquity of mobile devices, new ways of sensing context and the emergence of the mobile Web, digital storytelling is escaping the confines of the desktop and intertwinging in new and interesting ways with the physical world. Mobile, location aware, narrative systems are being applied to a range of areas including tour guides, educational tools and interactive fiction. Despite this there is little understanding of how these applications are related or how they link with existing hypertext models and theory.We argue that location aware narrative systems tend to follow three patterns (canyons, deltas and plains) and that it is possible to represent all of these patterns in a conceptual sculptural hypertext model. Our model builds on a general sculptural mechansim (of pre-conditions and behaviours) to include locality and narrative transitions as first class elements, opening the possibility of standardised viewers, formats, and hybrid stories. We show how existing structures can be mapped onto this conceptual sculptural model, and how narratives defined in the model can take advantage of open data sources and sensed contextual data. To demonstrate this we present the GeoYarn system, a prototype which implements the model to create interactive, location aware narratives, using all three patterns
A Topic Modeling based Representation to Detect Tweet Locations: Example of the event "Je suis Charlie"
Get PDFPresented as poster at ISPRS Geospatial Week 2015, La Grande Motte, France, 28 September - 2 October 2015International audienceSocial Networks became a major actor in information propagation. Using the Twitter popular platform, mobile users post or relay messages from different locations. The tweet content, meaning and location, show how an event-such as the bursty one ”JeSuisCharlie”, happened in France in January 2015, is comprehended in different countries. This research aims at clustering the tweets according to the co-occurrence of their terms, including the country, and forecasting the probable country of a non-located tweet, knowing its content. First, we present the process of collecting a large quantity of data from the Twitter website. We finally have a set of 2,189 located tweets about “Charlie”, from the 7th to the 14th of January. We describe an original method adapted from the Author-Topic (AT) model based on the Latent Dirichlet Allocation (LDA) method. We define an homogeneous space containing both lexical content (words) and spatial information (country). During a training process on a part of the sample, we provide a set of clusters (topics) based on statistical relations between lexical and spatial terms. During a clustering task, we evaluate the method effectiveness on the rest of the sample that reaches up to 95% of good assignment. It shows that our model is pertinent to foresee tweet location after a learning process
The Blind Men and the Elephant: Towards an Empirical Evaluation Framework for Software Sustainability
Get PDFSoftware sustainability has been identified as one of the key challenges in the development of scientific and engineering software as we move towards new paradigms of research and computing infrastructures. However, it is suggested that sustainability is not well understood within the software engineering community, which can led to ineffective and inefficient efforts to address the concept or result in its complete omission from the software system. This paper proposes a definition of software sustainability and considers how it can be measured empirically in the design and engineering process of software systems
Developments in High-Density Cobra Fiber Positioners for the Subaru Telescope's Prime Focus Spectrometer
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Author Correction: Comprehensive analysis of chromothripsis in 2,658 human cancers using whole-genome sequencing
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INDIGENOUS LAND TENURE AND LAND USE IN ALASKA: COMMUNITY IMPACTS OF THE ALASKA NATIVE CLAIMS SETTLEMENT ACT
Get PDFThrough the utilization of qualitative methods such as archival analysis, semi-structured interviewing, comparative and extended case studies, and observation, this paper closely examines two related Alaska Native communities. Our purpose is to document the impact of the Alaska Native Claims Settlement Act of 1971 (ANCSA) on land tenure, land use, and community structure. In all, 41 interviews were conducted, focusing on the following issues: (1) the role of the tribal government in relation to the regional and village corporate structure; (2) the recent changes in traditional land uses; and (3) how group decisions are made regarding land management and distribution of resources. By locating ANCSA within a broader context of economic, political, and cultural globalization that seeks to substitute traditional collective rights in land with individual tenure in a "free market" economy, the findings of this research may carefully and cautiously be applied beyond North America to other indigenous-state struggles regarding control of land and resources.United States. -- [Alaska Native Claims Settlement Act], Indians of North America -- Legal status, laws, etc. -- Alaska, Land tenure -- Law and legislation -- Alaska, Indians of North America -- Alaska -- Claims, Indians of North America -- Land tenure -- Alaska, Indians of North America -- Alaska -- Government relations -- History, Land Economics/Use,
Schools and student achievement: more evidence from the Milwaukee parental choice program
Get PDFUsing math and reading test score gains, the author compares the achievement of students in the nonsectarian private schools participating in Milwaukee's Parental Choice Program with the achievement of students in a wide range of Milwaukee's public schools. Her results point to the need for a better understanding of what makes a school successful.Education
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