295 research outputs found

    Electrosynthesis and characterisation of functionalised poly(indoles)

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    Kierkegaard's critique of rationalism

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    I. KIERKEGAARD'S LIFE AND WORKS: A "DEFENSE" OF MAN • II. THE DEVELOPMENT OF RATIONALISM: DESCARTES TO HEGEL • III. KIERKEGAARD'S CONCEPTION OF RATIONALISM • IV. DISSOLUTION: 'THE CROWD' • V. RECONSTRUCTION: 'THE INDIVIDUAL' • NOTES TO TEXT • BIBLIOGRAPH

    Putting Randomized Compiler Testing into Production (Artifact)

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    This artifact accompanies our experience report for our compiler testing technology transfer project: taking the GraphicsFuzz research project on randomized metamorphic testing of graphics shader compilers, and building the necessary tooling around it to provide a highly automated process for improving the Khronos Vulkan Conformance Test Suite (CTS) with test cases that expose fuzzer-found compiler bugs, or that plug gaps in test coverage. The artifact consists of two Dockerfiles and associated files that can be used to build two Docker containers. The containers include our main tool for performing fuzzing: gfauto. The containers allow the user to fuzz SwiftShader, a software Vulkan implementation, finding 4 bugs. The user will also perform some line coverage analysis of SwiftShader using our tools to synthesize a small test that increases line coverage. Ubuntu, gfauto, SwiftShader, and other dependencies inside the Docker containers are fixed at specific versions, and all random seeds are set to specific values. Thus, all examples should reproduce faithfully on any machine

    GPUVerify: A Verifier for GPU Kernels

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    We present a technique for verifying race- and divergence-freedom of GPU kernels that are written in mainstream ker-nel programming languages such as OpenCL and CUDA. Our approach is founded on a novel formal operational se-mantics for GPU programming termed synchronous, delayed visibility (SDV) semantics. The SDV semantics provides a precise definition of barrier divergence in GPU kernels and allows kernel verification to be reduced to analysis of a sequential program, thereby completely avoiding the need to reason about thread interleavings, and allowing existing modular techniques for program verification to be leveraged. We describe an efficient encoding for data race detection and propose a method for automatically inferring loop invari-ants required for verification. We have implemented these techniques as a practical verification tool, GPUVerify, which can be applied directly to OpenCL and CUDA source code. We evaluate GPUVerify with respect to a set of 163 kernels drawn from public and commercial sources. Our evaluation demonstrates that GPUVerify is capable of efficient, auto-matic verification of a large number of real-world kernels

    Auto-extinction of engineered timber

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    Engineered timber products are becoming increasingly popular in the construction industry due to their attractive aesthetic and sustainability credentials. Cross-laminated timber (CLT) is one such engineered timber product, formed of multiple layers of timber planks glued together with adjacent layers perpendicular to each other. Unlike traditional building materials such as steel and concrete, the timber structural elements can ignite and burn when exposed to fire, and thus this risk must be explicitly addressed during design. Current design guidance focusses on the structural response of engineered timber, with the flammability risk typically addressed by encapsulation of any structural timber elements with the intention of preventing their involvement in a fire. Exposed structural timber elements may act as an additional fuel load, and this risk must be adequately quantified to satisfy the intent of the building regulations in that the structure does not continue burning. This can be achieved through timber’s natural capacity to auto-extinguish when the external heat source is removed or sufficiently reduced. To address these issues, a fundamental understanding of auto-extinction and the conditions necessary to achieve it in real fire scenarios is needed. Bench-scale flammability studies were undertaken in the Fire Propagation Apparatus to explore the conditions under which auto-extinction will occur. Critical conditions were determined experimentally as a mass loss rate of 3.48 ± 0.31 g/m2s, or an incident heat flux of ~30 kW/m2. Mass loss rate was identified as the better criterion, as critical heat flux was shown by comparison with literature data to be heavily dependent on apparatus. Subsequently, full-scale compartment fire experiments with exposed timber surfaces were performed to determine if auto-extinction could be achieved in real fire scenarios. It was demonstrated that auto-extinction could be achieved in a compartment fire scenario, but only if significant delamination of the engineered timber product could be prevented. A full-scale compartment fire experiment with an exposed back wall and ceiling achieved auto-extinction after around 21 minutes, at which point no significant delamination of the first lamella had been observed. Experiments with an exposed back and side wall, and experiments with an exposed back wall, side wall, and ceiling underwent sustained burning due to repeated delamination, and an increased quantity of exposed timber respectively. Firepoint theory was used to predict the mass loss rate as a function of external heat flux and heat losses, and was successfully applied to the bench-scale experiments. This approach was then extended to the full-scale compartment fire experiment which achieved auto-extinction. A simplified approach based on experimentally obtained internal temperature fields was able to predict auto-extinction if delamination had not occurred – predicting an extinction time of 20-21 minutes. This demonstrates that the critical mass loss rate of 3.48 ± 0.31 g/m2s determined from bench-scale experiments was valid for application to full-scale compartment fire experiments. This was further explored through a series of reduced-scale compartment fire experiments, demonstrating that auto-extinction can only reliably be achieved if burnout of the compartment fuel load is achieved before significant delamination of the outer lamella takes place. The quantification of the auto-extinction phenomena and their applicability to full-scale compartment fires explored herein thus allows greater understanding of the effects of exposed timber surfaces on compartment fire dynamics

    Feeling clumsy and curious. A collective reflection on experimenting with poetry as an unconventional method

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    In this paper, we offer a collective, multi-vocal reflection on using poetry for research purposes. These were reflections on an online sub-plenary session organized as a workshop, which was held at the European Group for Organization Studies conference in 2021. During this workshop, the first three authors presented a step-by-step method for doing poetic inquiry and invited participants to apply it to their own empirical data or research praxis. The method was created in response to the marginalization of affect and embodiment in mainstream research in organization studies. Poetic inquiry aims to formulate specific practices of “writing differently” that assist researchers in their attempts to analyze and articulate their findings in embodied and affec-tive ways. In this paper, we describe the method and bring together multi-vocal reflections from the participants and organizers of the workshop on the affects of poetic inquiry and the (ethical) questions that it poses.Publisher PDFPeer reviewe

    Does shear wave ultrasound independently predict axillary lymph node metastasis in women with invasive breast cancer?

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    Shear wave elastography (SWE) shows promise as an adjunct to greyscale ultrasound examination in assessing breast masses. In breast cancer, higher lesion stiffness on SWE has been shown to be associated with features of poor prognosis. The purpose of this study was to assess whether lesion stiffness at SWE is an independent predictor of lymph node involvement. Patients with invasive breast cancer treated by primary surgery, who had undergone SWE examination were eligible. Data were retrospectively analysed from 396 consecutive patients. The mean stiffness values were obtained using the Aixplorer(®) ultrasound machine from SuperSonic Imagine Ltd. Measurements were taken from a region of interest positioned over the stiffest part of the abnormality. The average of the mean stiffness value obtained from each of two orthogonal image planes was used for analysis. Associations between lymph node involvement and mean lesion stiffness, invasive cancer size, histologic grade, tumour type, ER expression, HER-2 status and vascular invasion were assessed using univariate and multivariate logistic regression. At univariate analysis, invasive size, histologic grade, HER-2 status, vascular invasion, tumour type and mean stiffness were significantly associated with nodal involvement. Nodal involvement rates ranged from 7 % for tumours with mean stiffness <50 kPa to 41 % for tumours with a mean stiffness of >150 kPa. At multivariate analysis, invasive size, tumour type, vascular invasion, and mean stiffness maintained independent significance. Mean stiffness at SWE is an independent predictor of lymph node metastasis and thus can confer prognostic information additional to that provided by conventional preoperative tumour assessment and staging

    Characterisation of QTL-linked and genome-wide restriction site-associated DNA (RAD) markers in farmed Atlantic salmon

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    Background: Restriction site-associated DNA sequencing (RAD-Seq) is a genome complexity reduction technique that facilitates large-scale marker discovery and genotyping by sequencing. Recent applications of RAD-Seq have included linkage and QTL mapping with a particular focus on non-model species. In the current study, we have applied RAD-Seq to two Atlantic salmon families from a commercial breeding program. The offspring from these families were classified into resistant or susceptible based on survival/mortality in an Infectious Pancreatic Necrosis (IPN) challenge experiment, and putative homozygous resistant or susceptible genotype at a major IPN-resistance QTL. From each family, the genomic DNA of the two heterozygous parents and seven offspring of each IPN phenotype and genotype was digested with the SbfI enzyme and sequenced in multiplexed pools. Results: Sequence was obtained from approximately 70,000 RAD loci in both families and a filtered set of 6,712 segregating SNPs were identified. Analyses of genome-wide RAD marker segregation patterns in the two families suggested SNP discovery on all 29 Atlantic salmon chromosome pairs, and highlighted the dearth of male recombination. The use of pedigreed samples allowed us to distinguish segregating SNPs from putative paralogous sequence variants resulting from the relatively recent genome duplication of salmonid species. Of the segregating SNPs, 50 were linked to the QTL. A subset of these QTL-linked SNPs were converted to a high-throughput assay and genotyped across large commercial populations of IPNV-challenged salmon fry. Several SNPs showed highly significant linkage and association with resistance to IPN, and population linkage-disequilibrium-based SNP tests for resistance were identified. Conclusions: We used RAD-Seq to successfully identify and characterise high-density genetic markers in pedigreed aquaculture Atlantic salmon. These results underline the effectiveness of RAD-Seq as a tool for rapid and efficient generation of QTL-targeted and genome-wide marker data in a large complex genome, and its possible utility in farmed animal selection programs

    Loss of Tet1 associated 5-hydroxymethylcytosine is concomitant with aberrant promoter hypermethylation in liver cancer

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    Aberrant hypermethylation of CpG islands (CGI) in human tumors occurs predominantly at repressed genes in the host tissue, but the preceding events driving this phenomenon are poorly understood. In this study, we temporally tracked epigenetic and transcriptomic perturbations which occur in a mouse model of liver carcinogenesis. Hypermethylated CGI events in the model were predicted by enrichment of the DNA modification 5-hydroxymethylcytosine (5hmC) and the histone H3 modification H3K27me3 at silenced promoters in the host tissue. During cancer progression, CGI underwent hypo-hydroxymethylation prior to hypermethylation, whilst retaining H3K27me3. In livers from mice deficient in Tet1, a tumor suppressor involved in cytosine demethylation, we observed a similar loss of promoter core 5hmC, suggesting that reduced Tet1 activity at CGI may contribute to epigenetic dysregulation observed during hepatocarcinogenesis. Consistent with this possibility, mouse liver tumors exhibited reduced Tet1 protein levels. Similar to humans, DNA methylation changes at CGI in mice did not appear to be direct drivers of hepatocellular carcinoma progression, rather, dynamic changes in H3K27me3 promoter deposition correlated strongly with tumor-specific activation and repression of transcription. Overall, our results suggest that loss of promoter-associated 5hmC in liver tumors licenses reprogramming of DNA methylation at silent CGI during progression
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