8,581 research outputs found

    The first comprehensive description of the biodiversity and biogeography of Antarctic and Sub-Antarctic intertidal communities

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    Aim To describe the distribution of biodiversity and biogeographical patterns of intertidal organisms in southern temperate and polar waters. We hypothesized that there would be differences in community structure between the Antarctic, which is most affected by ice, and the sub-Antarctic and other neighbouring regions. We also hypothesized that rafting and West Wind Drift will be the significant drivers of biogeographical patterns. Additionally, the size, age, isolation, volcanic or glacial history of a region and the presence of large, beach dwelling, mammals and birds would all play a role in determining the level of biodiversity observed. Location South Atlantic, Indian and Pacific Oceans and the Southern Ocean. Methods We examined all available intertidal records from the Antarctic and sub-Antarctic with additional data from neighbouring regions for comparison and context. We compiled 3902 occurrences of 1416 species of high southern latitude intertidal organisms from 229 locations and used PRIMER 6 to perform multivariate statistical analyses. Results The Antarctic and sub-Antarctic are shown to be distinct biogeographical regions, with patterns driven by a small number of widely distributed species. These wide-ranging molluscs and macroalgae dominate the biogeographical structure of the Southern Ocean intertidal, most likely as a result of rafting in the Antarctic Circumpolar Current. East Antarctic intertidal habitats are potentially isolated by the Ross and Weddell Sea ice shelves but represent a great unknown in this biogeographical scheme. Main Conclusions The view that the Antarctic intertidal is a lifeless desert does not hold true, with Antarctic Peninsula intertidal communities being richer and more diverse than those in southern South America and the sub-Antarctic islands. Changing conditions in the Antarctic and sub-Antarctic intertidal mean that a representative baseline is needed (acquired through standardized and quantitative sampling) to assess future changes and to detect any invasive species

    An experimental and finite element study of the low-cycle fatigue failure of a galvanised steel lighting column

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    This paper presents the results of a low-cycle fatigue test on a lighting column. The wind induced vibration phenomena responsible for low cycle fatigue in such structures is discussed and the failure mechanism is examined. It was initially thought that poor quality weld detail was the major influence on the fatigue life of such columns. However, the significant role of the galvanised coating in the failure process is also highlighted. The experimental results are compared with those from a detailed 3D finite element model. Various methods of calculating hot-spot stresses at welded joints are examined and use of a simple peak stress removal approach is shown to produce significantly different values compared with the other methods examined

    Practical applications of small-angle neutron scattering.

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    Recent improvements in beam-line accessibility and technology have led to small-angle neutron scattering (SANS) becoming more frequently applied to materials problems. SANS has been used to study the assembly, dispersion, alignment and mixing of nanoscale condensed matter, as well as to characterise the internal structure of organic thin films, porous structures and inclusions within steel. Using time-resolved SANS, growth mechanisms in materials systems and soft matter phase transitions can also be explored. This review is intended for newcomers to SANS as well as experts. Therefore, the basic knowledge required for its use is first summarised. After this introduction, various examples are given of the types of soft and hard matter that have been studied by SANS. The information that can be extracted from the data is highlighted, alongside the methods used to obtain it. In addition to presenting the findings, explanations are provided on how the SANS measurements were optimised, such as the use of contrast variation to highlight specific parts of a structure. Emphasis is placed on the use of complementary techniques to improve data quality (e.g. using other scattering methods) and the accuracy of data analysis (e.g. using microscopy to separately determine shape and size). This is done with a view to providing guidance on how best to design and analyse future SANS measurements on materials not listed below

    The Allocation of Merit Pay in Academia: A Case Study

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    This paper investigates whether the widespread awarding of faculty merit pay at a large public university accurately reflects productivity. We show that pairwise voting on a quality standard by a committee can in theory be consistent with observed allocation patterns. However, the data indicate only nominal adherence to a quality standard. Departments with more severe compression issues are more likely to award merit pay as a countermeasure and some departments appear to be motivated by nonpecuniary incentives. Much of the variance in merit pay allocation remains unexplained. These results suggest reform is needed to improve transparency in the merit system.merit, faculty compensation

    Precision teaching and fluency: the effects of charting and goal-setting on skaters’ performance

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    This research involved three successive studies where precision teaching methods were used to increase roller skaters performance rates of basic skating skills. The first study compared precision teaching methods both with and without the use of charting in a group design, and compared both within-subject and betweensubject differences for 12 skaters. Results showed that charting did not increase performance rates over that seen when charting was not used. The second study was a group design which compared two different types of goals, or performance aims, on skaters‟ performance. No difference was found between the two groups of 5 skaters when one group used a fixed, difficult goal and a second used a flexible, easier goal. In the final study, a single-subject design was used and 8 skaters completed a control condition where no goals were set before a goal was introduced for 4 skaters. It was found that an immediate increase in performance rates occurred following the introduction of the goal. Overall these three studies showed that skaters improved their performance rates over sessions, even in the absence of charting and/or goals, demonstrating that precision teaching can be applied to the sport of roller skating

    Surrogate Accelerated Bayesian Inversion for the Determination of the Thermal Diffusivity of a Material

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    Determination of the thermal properties of a material is an important task in many scientific and engineering applications. How a material behaves when subjected to high or fluctuating temperatures can be critical to the safety and longevity of a system's essential components. The laser flash experiment is a well-established technique for indirectly measuring the thermal diffusivity, and hence the thermal conductivity, of a material. In previous works, optimization schemes have been used to find estimates of the thermal conductivity and other quantities of interest which best fit a given model to experimental data. Adopting a Bayesian approach allows for prior beliefs about uncertain model inputs to be conditioned on experimental data to determine a posterior distribution, but probing this distribution using sampling techniques such as Markov chain Monte Carlo methods can be incredibly computationally intensive. This difficulty is especially true for forward models consisting of time-dependent partial differential equations. We pose the problem of determining the thermal conductivity of a material via the laser flash experiment as a Bayesian inverse problem in which the laser intensity is also treated as uncertain. We introduce a parametric surrogate model that takes the form of a stochastic Galerkin finite element approximation, also known as a generalized polynomial chaos expansion, and show how it can be used to sample efficiently from the approximate posterior distribution. This approach gives access not only to the sought-after estimate of the thermal conductivity but also important information about its relationship to the laser intensity, and information for uncertainty quantification. We also investigate the effects of the spatial profile of the laser on the estimated posterior distribution for the thermal conductivity

    Das Briefgeheimnis: Ingeborg Bachmann and Paul Celan's Poetics of Correspondence

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    Ingeborg Bachmann and Paul Celan are two of the foremost German-language poets of the post-1945 era. Celan, a Jewish poet whose parents were murdered in the Holocaust, and Bachmann, the Austrian daughter of a National Socialist, both sought a way to write after atrocity. Both writers struggled to use German as a poetic medium in their poetry and prose, as language appeared to have been poisoned through its association with National Socialism. Wider cultural concerns such as Theodor Adorno's dictum that to write poetry after Auschwitz is barbaric influenced the post-catastrophic literary landscape. In 1958, Celan famously compared writing poetry after 1945 to sending out a message in a bottle. This metaphor characterizes his dialogic approach to writing poetry. Famously, Bachmann and Celan carried out a poetic dialogue in their published work as they shared motifs and themes which they reinterpreted in their own works. From the time that Bachmann and Celan first met in Vienna in 1948, they began exchanging letters and poetry until Celan's death in 1970. In 2008, the letters that Bachmann and Celan exchanged between 1948 and 1967 were published for the first time in the volume Herzzeit. These letters provide new insights into the authors' struggle to find a viable mode of expression after 1945, and how they sought to overcome these problems through constructing a dialogue. This thesis will argue that Bachmann and Celan continued their poetic dialogue in some of the letters and that these letters serve as a poetic form in their own right

    How a Computer-Assisted Instructional Program Affects the Reading Fluency of a Selected Group of 2nd Grade Students

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    This study examined the effectiveness of Headsprout Early Reading to augment fluency abilities for second grade students in an urban public school system. Headsprout, a Computer-Assisted Instruction program (CAI), provided internet-based reading instruction based on the National Reading Panel\u27s recommendations. All second grade students were assessed to determine who would use the program. Second grade students who participated in Headsprout sessions were compared with second grade students who did not use Headsprout. All participants were assessed again at the end of the study.Analysis of the students\u27 gains was conducted using a Repeated Measures Analysis of Variance (R-ANOVA). It revealed that the participants showed more growth from their entry benchmark and exit benchmark scores than from their entry benchmark and mid-entry benchmark scores. Results of a Regression-Discontinuity Data design approach analysis showed an observable discontinuity between the mean averages for the treatment group and control group. Overall, results were more significant for those studentswho had participated in the program

    Pricing and Time on the Market for Residential Properties in a Major U.K. City

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    The pricing and length of time to sell single-family residential properties is a function of the interaction between buyer and seller behavior. This study estimates value effects in relation to the time on the market for residential properties within the Belfast (U.K).metropolitan area. Three distinctive characteristics of market are highlighted. First, the majority of sales are at a premium to the list price. Second, different factors influence time on the market for premium and discount sales. Third, the marketing period is examined for three events: listing to sales agreement, sales agreement to completion, and listing to completion.

    Evaluation of low vision services on the quality of life of individuals with age-related macular degeneration

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    Background: Age-related macular degeneration (ARMD) is a major cause of irreversible visual loss in the elderly and a significant threat to their quality of life. Although low vision services often improve the functional outcomes of individuals with macular disease, it remains unclear whether or not they have any impact on quality of life. The principal aim of this study was to determine the effect of a hospital-based low vision clinic on the quality of life of individuals with ARMD. Methods: Forty patients with ARMD attended the low vision clinic at Milton Keynes University Hospital. Quality of life was measured with the vision-specific Low Vision Quality of Life (LVQOL) questionnaire and the general health EuroQol (EQ-5D-5L) questionnaire. Measures were completed at baseline (time zero, T0), and at three- (T3) and six-month (T6) follow-up visits. Results: The near visual acuity of individuals attending the low vision clinic for the first time improved significantly between visits T0 and T3 (p=0.005), reflecting the practiced use of their newly-dispensed low vision aids. As expected, there was no significant change in near acuity over this time period for existing patients. For both new and existing patients, a significant increase in LVQOL score was evident between visits T0 and T3, with a further significant improvement between T3 and T6. Similarly, there was a significant decrease in EQ-5D-5L questionnaire scores between visits T0 and T6. Conclusions: The higher LVQOL scores obtained at the end of the study period (T6) provide evidence that low vision services at Milton Keynes University Hospital served to improve patient quality of life. The reduction in EQ-5D-5L scores over the same time period suggests that low vision services also provide for an improvement in general health-related quality of life. Impact: The findings support the cause of low vision services to improve not only the vision and functional outcomes of individuals with macular disease but also their quality of life. Moreover, the findings suggest that a more efficient allocation of resources at low vision clinics may be possible through the standardisation of patient follow-up frequency
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