509 research outputs found

    Towards a chiral gauge theory by deconstruction in AdS5

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    We describe an implementation of a deconstructed gauge theory with charged fermions defined on an interval in five dimensional AdS space. The four dimensional slices are Minkowski, and the end slices support four dimensional chiral zero modes. In such a theory, the energy scales warp down as we move along the fifth dimension. If we augment this theory with localized neutral 4-dimensional Majorana fermions on the low energy end, and implement a Higgs mechanism there, we can arrange the theory such that the lightest gauge boson mode and the chiral mode on the wall at the high energy end are parametrically lighter than all the other states in the theory. If this semiclassical construction does not run into problems at the quantum level, this may provide an explicit construction of a chiral gauge theory. Instanton effects are expected to make the gauge boson heavy only if the resulting effective theory is anomalous.Comment: 6 pages, 3 figures, presented at Lattice2005(Chiral fermions), Dublin, July 25-30, 2005, to appear in Proceedings of Scienc

    Massive gas gangrene secondary to occult colon carcinoma

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    AbstractGas gangrene is a rare but often fatal soft-tissue infection. Because it is uncommon and the classic symptom of crepitus does not appear until the infection is advanced, prompt diagnosis requires a high index of suspicion. We present a case report of a middle-aged man who presented with acute onset lower-extremity pain that was initially thought to be due to deep vein thrombosis. After undergoing workup for pulmonary embolism, he was found to have massive gas gangrene of the lower extremity secondary to an occult colon adenocarcinoma and died within hours of presentation from multisystem organ failure

    High Frequency Sampling of TTL Pulses on a Raspberry Pi for Diffuse Correlation Spectroscopy Applications

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    Diffuse Correlation Spectroscopy (DCS) is a well-established optical technique that has been used for non-invasive measurement of blood flow in tissues. Instrumentation for DCS includes a correlation device that computes the temporal intensity autocorrelation of a coherent laser source after it has undergone diffuse scattering through a turbid medium. Typically, the signal acquisition and its autocorrelation are performed by a correlation board. These boards have dedicated hardware to acquire and compute intensity autocorrelations of rapidly varying input signal and usually are quite expensive. Here we show that a Raspberry Pi minicomputer can acquire and store a rapidly varying time-signal with high fidelity. We show that this signal collected by a Raspberry Pi device can be processed numerically to yield intensity autocorrelations well suited for DCS applications. DCS measurements made using the Raspberry Pi device were compared to those acquired using a commercial hardware autocorrelation board to investigate the stability, performance, and accuracy of the data acquired in controlled experiments. This paper represents a first step toward lowering the instrumentation cost of a DCS system and may offer the potential to make DCS become more widely used in biomedical applications.Radiation Monitoring Devices, Inc

    Assessing the efficacy of TNF-alpha inhibitors in preventing emergency and emergent colectomies

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    Background and Aim: Severe ulcerative colitis (UC) is potentially life threatening and is associated with significant morbidity. TNF-∝ inhibitors (Infliximab) were introduced in Australia for the management of medically resistant, acute, severe flares of UC in 2008. The aim of this study is to assess the efficacy of Infliximab in preventing emergent and emergency colectomies for patients with moderate to severe UC by comparing colectomy rates before and after its introduction at our institution. Methods: This was a retrospective cohort study of all patients who were admitted to the Royal Perth Hospital with a flare of UC between 2002 and 2017. Patients were divided into two cohorts: those admitted prior to the introduction of Infliximab (pre-2008) and those admitted after. We compared data between these two groups, including age, gender, length of admission, use of Infliximab, colectomy, and complications of surgery. We defined emergency surgery as requiring surgery during the index admission and emergent surgery as an operation within 54 weeks. Results: A total of 313 UC cases from 2002 to 2017 were analyzed. There was a decrease in emergency and emergent colectomies from 19.4 to 8% in the post-2008 cohort (P = 0.008). Furthermore, there was a decrease in the proportion of operations performed as emergencies, from 36 to 20%. This resulted in a significantly reduced length of stay (13.4–9.7 days, P \u3c 0.05) and complication rate (36 to 20%, P \u3c 0.05). Conclusion: Overall, the need for emergency and emergent operations has drastically reduced at our institution with the introduction of Infliximab. This study has confirmed the efficacy of Infliximab in reducing colectomy rates at our institution. © 2019 The Authors. JGH Open: An open access journal of gastroenterology and hepatology published by Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd

    Microstructure-guided numerical simulations to predict the thermal performance of a hierarchical cement-based composite material

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    This paper presents a microstructure-guided numerical homogenization technique to predict the effective thermal conductivity of a hierarchical cement-based material containing phase change material (PCM)-impregnated lightweight aggregates (LWA). Porous inclusions such as LWAs embedded in a cementitious matrix are filled with multiple fluid phases including PCM to obtain desirable thermal properties for building and infrastructure applications. Simulations are carried out on realistic three-dimensional microstructures generated using pore structure information. An inverse analysis procedure is used to extract the intrinsic thermal properties of those microstructural components for which data is not available. The homogenized heat flux is predicted for an imposed temperature gradient from which the effective composite thermal conductivity is computed. The simulated effective composite thermal conductivities are found to correlate very well with experimental measurements for a family of LWA-PCM composites considered in the paper. Comparisons with commonly used analytical homogenization models show that the microstructure-guided simulation approach provides superior results for composites exhibiting large property contrast between phases. By linking the microstructure and thermal properties of hierarchical materials, an efficient framework is available for optimizing the material design to improve thermal efficiency of a wide variety of heterogeneous materials

    Visualization of High-Dimensional Combinatorial Catalysis Data

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    The role of various techniques for visualization of high-dimensional data is demonstrated in the context of combinatorial high-throughput experimentation (HTE). Applying visualization tools, we identify which constituents of catalysts are associated with final products in a huge combinatorially generated data set of heterogeneous catalysts, and catalytic activity regions are identified with respect to pentanary composition spreads of catalysts. A radial visualization scheme directly visualizes pentanary composition spreads in two-dimensional (2D) space and catalytic activity of a final product by combining high-throughput results from five slate libraries. A glyph plot provides many possibilities for visualizing high-dimensional data with interactive tools. For catalyst discovery and lead optimization, this work demonstrates how large multidimensional catalysis data sets are visualized in terms of quantitative composition activity relationships (QCAR) to effectively identify the relevant key role of compositions (i.e., lead compositions) of catalysts

    Structurally Complex Osteosarcoma Genomes Exhibit Limited Heterogeneity within Individual Tumors and across Evolutionary Time

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    Osteosarcoma is an aggressive malignancy characterized by high genomic complexity. Identification of few recurrent mutations in protein coding genes suggests that somatic copy-number aberrations (SCNA) are the genetic drivers of disease. Models around genomic instability conflict-it is unclear whether osteosarcomas result from pervasive ongoing clonal evolution with continuous optimization of the fitness landscape or an early catastrophic event followed by stable maintenance of an abnormal genome. We address this question by investigating SCNAs in >12,000 tumor cells obtained from human osteosarcomas using single-cell DNA sequencing, with a degree of precision and accuracy not possible when inferring single-cell states using bulk sequencing. Using the CHISEL algorithm, we inferred allele- and haplotype-specific SCNAs from this whole-genome single-cell DNA sequencing data. Surprisingly, despite extensive structural complexity, these tumors exhibit a high degree of cell-cell homogeneity with little subclonal diversification. Longitudinal analysis of patient samples obtained at distant therapeutic timepoints (diagnosis, relapse) demonstrated remarkable conservation of SCNA profiles over tumor evolution. Phylogenetic analysis suggests that the majority of SCNAs were acquired early in the oncogenic process, with relatively few structure-altering events arising in response to therapy or during adaptation to growth in metastatic tissues. These data further support the emerging hypothesis that early catastrophic events, rather than sustained genomic instability, give rise to structural complexity, which is then preserved over long periods of tumor developmental time. SIGNIFICANCE: Chromosomally complex tumors are often described as genomically unstable. However, determining whether complexity arises from remote time-limited events that give rise to structural alterations or a progressive accumulation of structural events in persistently unstable tumors has implications for diagnosis, biomarker assessment, mechanisms of treatment resistance, and represents a conceptual advance in our understanding of intratumoral heterogeneity and tumor evolution

    Challenges and opportunities for agroforestry practitioners to participate in state preferential property tax programs for agriculture and forestry

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    All 50 states offer preferential property tax programs that lower the taxes paid on enrolled agricultural and/or forest lands. While agroforestry is a land-use that combines elements of both agriculture and forestry, eligibility criteria and other rules and regulations may prevent landowners from enrolling agroforestry practices in one or more of the agricultural and forestry tax programs. This pilot-scale study developed conceptual and methodological frameworks to identify the current barriers to and opportunities in preferential tax policies applicable to agroforestry practices. We conducted an extensive review of state preferential property tax programs relevant for agroforestry practices, following focus group discussions with regional experts in five selected states across the United States: North Carolina, Nebraska, Wisconsin, New York, and Oregon. Based on a systematic review of statutes and their supporting documents, we developed a database of programs, which support or create barriers to enrollment of agroforestry practitioners into the programs. We found that agricultural tax assessments were more likely to favor multi-use agriculture and forestry systems than the preferential tax assessments of forestlands in the five states. Forest farming and silvopasture, followed by alley cropping, windbreaks, and riparian forest buffers, were found to be the most common agroforestry practices allowed under preferential tax classifications in the study states. This study provides a framework for cataloging and analyzing preferential property tax-programs to document barriers and facilitators to agroforestry practices in the United States
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