Time scales and modes of reef lagoon infilling in the Maldives and controls on the onset of reef island formation

Faro are annular reefs, with reef flats near sea level and lagoons of variable depth, characteristic of both the perimeter and lagoons of Maldivian (Indian Ocean) atolls. Their geomorphic development remains largely unknown, but where faro lagoons (termed velu in Maldivian) have infilled and support reef islands, these provide precious habitable land. Understanding the timing and modes of velu infilling is thus directly relevant to questions about reef island development and vulnerability. Here we use a chronostratigraphic data set obtained from a range of atoll-interior faro with partially to fully filled velu (including those with reef islands) from Baa (South Maalhosmadulu) Atoll, Maldives, to determine time scales and modes of velu infilling, and to identify the temporal and spatial thresholds that control reef island formation. Our data suggest a systematic relationship between faro size, velu infilling, and island development. These relationships likely vary between atolls as a function of atoll lagoon depth, but in Baa Atoll, our data set indicates the following faro-size relationships exist: (1) faros <∼0.5 km2 have velu that were completely infilled by ca. 3000 calibrated years B.P. (cal yr B.P.) with islands having established on these deposits by ca. 2.5 cal kyr B.P.; (2) faros >0.5 km2 but <∼1.25 km2 have velu in late stages of infill, may support unvegetated sand cays and, given sufficient sand supply, may evolve into larger, more permanent islands; and (3) faros >∼1.25 km2 have unfilled (deeper) velu which might only infill over long time scales and which are thus unlikely to support new island initiation. These new observations, when combined with previously published data on Maldivian reef island development, suggest that while the velu of the largest faro are unlikely to fill over the next few centuries (at least), other faro with near-infilled velu may provide important foci for future reef-island building, even under present highstand (and slightly rising) sea levels

Mindful Escapism

This thesis examines the art work included in Kench Weathers’ MFA thesis exhibition. This work explores major themes such as the sacred, contemplation, optical illusion and paradox. The installations involve multiple three-dimensional geometric shapes that are formed with steel tubing (welded together). These works have various inspiration; both contemporary secular and sacred and are influenced by sacred paradox, both visual and ideological. The mixture of the two-dimensional with the three-dimensional creates multistable perception within the viewer. The work introduces visual and perceptual distortions of depth and dimensionality. These forms are nonrepresentational but act as a catalyst for the viewer. I create to escape, in hopes the viewer will have a similar cognitive experience. One could compare the aesthetic to minimalism wherein art objects focus on a pure form of the idea. My art is about arrangement and object and how they are presented and perceived by the viewer

Evaluating the development and effectiveness of grit and growth mindset among high school students in a computer programming project

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science Johannesburg 2016.This dissertation investigates grit “passion and perseverance” for a long-term goal and growth mindset in grade 11 high school students as they code a non-trivial pro-gramming project in Java over a six-week period. Students are often challenged by the complexities of programming and can be overwhelmed when they encounter errors causing them to give up and not persevere. The programming project includes scaffolding with frequent feedback to increase the motivation of students. The study used mixed methods research that used both quantitative and qualitative data to find answers to the research questions. Whilst the correlation between grit, mindset and the project results were moderate, that students submitted their project numerous times showed an indication to perseverance. The data gathered from the interviews further indicated that the students’ perseverance led them to employ their own prob-lem-solving strategies when they encounter problems.MT 201

Terrigenous sediment-dominated reef platform infilling: an unexpected precursor to reef island formation and a test of the reef platform size-island age model in the Pacific

Low-lying coral reef islands are considered highly vulnerable to climate change, necessitating an improved understanding of when and why they form, and how the timing of formation varies within and among regions. Several testable models have been proposed that explain inter-regional variability as a function of sea-level history and, more recently, a reef platform size model has been proposed from the Maldives (central Indian Ocean) to explain intra-regional (intra-atoll) variability. Here we present chronostratigraphic data from Pipon Island, northern Great Barrier Reef (GBR), enabling us to test the applicability of existing regional island evolution models, and the platform size control hypothesis in a Pacific context. We show that reef platform infilling occurred rapidly (~4–5 mm yr−1) under a “bucket-fill” type scenario. Unusually, this infilling was dominated by terrigenous sedimentation, with platform filling and subsequent reef flat formation complete by ~5000 calibrated years BP (cal BP). Reef flat exposure as sea levels slowly fell post highstand facilitated a shift towards intertidal and subaerial-dominated sedimentation. Our data suggest, however, a lag of ~1500 yr before island initiation (at ~3200 cal BP), i.e. later than that reported from smaller and more evolutionarily mature reef platforms in the region. Our data thus support: (1) the hypothesis that platform size acts to influence the timing of platform filling and subsequent island development at intra-regional scales; and (2) the hypothesis that the low wooded islands of the northern GBR conform to a model of island formation above an elevated reef flat under falling sea levels

A qualitative study of the development of a multidisciplinary case conference review methodology to reduce involved margins in pelvic exenteration surgery for recurrent rectal cancer

Aim Pelvic exenteration surgery remains the only curative option for recurrent rectal cancer. Microscopically involved surgical margins (R1) are associated with a higher risk of local recurrence and decreased survival. Our study aimed to develop a post hoc multidisciplinary case conference review and investigate its potential for identifying areas for improvement. Method Results Patients who underwent pelvic exenteration surgery for recurrent rectal cancer with R1 resections at a tertiary referral centre between April 2014 and January 2016 were retrospectively reviewed from a prospectively maintained database. Patients with non-rectal cancers or who underwent palliative surgery were excluded. Cases, imaging and histopathology were evaluated by a dedicated panel including colorectal surgeons, an abdominal radiologist and a gastrointestinal pathologist. R1 resections were reported in 32 of 110 pelvic exenterations. Patients with other tumours were excluded and one patient had a palliative resection. Nine male patients with 11 exenterations were included with a median age of 56 years. All patients had positive soft tissue margins, and one patient also had an involved bony margin. Failures were due to (interdisciplinary) communication problems, specific management of tumour biology (multifocality, spiculated tumours), which can lead to radiological undercalling, and inadequate surgical technical planning. In hindsight, surgery would have been withheld from one patient. Conclusion A retrospective multidisciplinary case evaluation of pelvic exenteration patients with involved surgical margins led to a list of recommendations which included the need to plan for wider surgical soft tissue resections and improvement in interdisciplinary communication. Lessons learned may increase clear margin rates in future resections

The nature and origin of the minialbumin found in cadmium-poisoned animals

No Abstract

Mapping 2007-08 Tuition And Fees In Higher Education

Using data sets from US News & World Report and the Association to Advance Collegiate Schools of Business, this paper isolates 10 factors that account for 90 percent of the variation in tuition and fees across 523 institutions of higher learning in the United States.  It is hoped that the results will give guidance to schools by quantifying the costs and benefits of making a given change to their tuition and fee structure.&nbsp

Model Skill and Sensitivity for Simulating Wave Processes on Coral Reefs Using a Shock-Capturing Green-Naghdi Solver

International audienceWave flume data from published benchmark experiments were used to extensively evaluate numerical model skill and sensitivity for applying a shock-capturing Green-Naghdi (GN) model to simulate nonlinear wave transformation processes on complex coral reefs. Boussinesq-type models that utilise nonlinear shallow water equations (NSWEs) to represent wave breaking and dissipation hold significant potential for understanding coastal hazards associated with global environmental change and sea-level rise. These fully nonlinear phase-resolving models typically require a threshold condition to switch from dispersive equations to shock-capturing NSWEs in areas of active wave breaking. However, limited information exits regarding how this splitting approach influences the behaviour of different surf-zone processes that contribute to wave runup and inundation on coral reefs. This paper presents a comprehensive analysis of model sensitivity to explore how input parameters that control wave breaking and dissipation influence the behaviour of sea-swell (SS) waves, infragravity (IG) waves, wave setup, runup and solitary waves on coral reefs. Results show that each wave process exhibits unique sensitivity to the free-surface slope threshold (B) that is used to represent areas of active wave breaking by locally switching from the weakly-dispersive GN equations to the shock-capturing NSWEs. However, accurate representation of all wave processes can be achieved if the wave-face steepens to at least 35 degrees (B ≥ 0.7) before breaking is initiated. Results from this research support and encourage the use of nonlinear phase-resolving wave models as tools for academic research, coastal management, coastal engineering and hazard forecasting on atoll and fringing reef environments

Implications of reef ecosystem change for the stability and maintenance of coral reef islands

This is the author's post-print version of an article published in Global Change Biology, Vol. 17, pp. 3679 – 3696. Copyright © Wiley-Blackwell 2011. The definitive version is available at www3.interscience.wiley.comCoral reef islands are among the most vulnerable environments on Earth to climate change because they are low lying and largely constructed from unconsolidated sediments that can be readily reworked by waves and currents. These sediments derive entirely from surrounding coral reef and reef flat environments and are thus highly sensitive to ecological transitions that may modify reef community composition and productivity. How such modifications – driven by anthropogenic disturbances and on-going and projected climatic and environmental change – will impact reef island sediment supply and geomorphic stability remains a critical but poorly resolved question. Here, we review the unique ecological–geomorphological linkages that underpin this question and, using different scenarios of environmental change for which reef sediment production responses can be projected, explore the likely resilience of different island types. In general, sand-dominated islands are likely to be less resilient than those dominated by rubble grade material. However, because different islands typically have different dominant sediment constituents (usually either coral, benthic foraminifera or Halimeda) and because these respond differently to individual ecological disturbances, island resilience is likely to be highly variable. Islands composed of coral sands are likely to undergo major morphological change under most near-future ecological change scenarios, while those dominated by Halimeda may be more resilient. Islands composed predominantly of benthic foraminifera (a common state through the Pacific region) are likely to exhibit varying degrees of resilience depending upon the precise combination of ecological disturbances faced. The study demonstrates the critical need for further research bridging the ecological–geomorphological divide to understand: (1) sediment production responses to different ecological and environmental change scenarios; and (2) dependant landform vulnerability