1,189 research outputs found

    Decoration of the truncated tetrahedron - an Archimedean polyhedron - to produce a new class of convex equilateral polyhedra with tetrahedral symmetry

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    The Goldberg construction of symmetric cages involves pasting a patch cut out of a regular tiling onto the faces of a Platonic host polyhedron, resulting in a cage with the same symmetry as the host. For example, cutting equilateral triangular patches from a 6.6.6 tiling of hexagons and pasting them onto the full triangular faces of an icosahedron produces icosahedral fullerene cages. Here we show that pasting cutouts from a 6.6.6 tiling onto the full hexagonal and triangular faces of an Archimedean host polyhedron, the truncated tetrahedron, produces two series of tetrahedral (T-d) fullerene cages. Cages in the first series have 28n(2) vertices (n >= 1). Cages in the second (leapfrog) series have 3 x 28n(2). We can transform all of the cages of the first series and the smallest cage of the second series into geometrically convex equilateral polyhedra. With tetrahedral (T-d) symmetry, these new polyhedra constitute a new class of "convex equilateral polyhedra with polyhedral symmetry". We also show that none of the other Archimedean polyhedra, six with octahedral symmetry and six with icosahedral, can host full-face cutouts from regular tilings to produce cages with the host's polyhedral symmetry

    Development of a green material for horticulture

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    Poly(lactic acid) (PLA), used as a matrix, was mixed with wood fibers, coffee grounds, fertilizer and a foaming agent to develop an ecofriendly material to be used in horticulture. For this application materials should have mechanical properties similar to PLA, increased biodegradability and a lower price than currently used materials. The new materials were prepared by melt processing in an internal mixer at 190 ° C and were characterized by several techniques. The mechanical properties of the biocomposites, measured by flexural tests, were similar to neat PLA, even with a reduction of 40 wt% of polymer. Biodegradation assessment by composting tests in an aerobic environment demonstrated that the green materials exhibited higher biodegradability than PLA. Biocomposites containing wood fibers and fertilizer were revealed to be the most suitable for horticulture application, as these can combine mechanical properties, biodegradability and fertilizer release. Moreover, this green material has two main advantages: it can be prepared using materials from natural resources, and it does not generate any residue after use.n-STeP Project, NORTE-07-0124-FEDER-000039, supported by the Programa Operacional Regional do Norte (ON.2) and PEst- C/CTM/LA0025/2013 (Strategic Project-LA 25-2013-2014

    Shaping the Future Generation: Education Works

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    https://digitalcommons.pcom.edu/bridging_gaps2016/1004/thumbnail.jp

    Burden of comorbidity in systemic lupus erythematosus in the UK, 1999–2012

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    Objective: To estimate the comorbidity associated with systemic lupus erythematosus (SLE) in the UK during 1999–2012. Methods: A retrospective cohort study using the UK Clinical Practice Research Datalink was conducted. Prevalent cases of SLE were matched by age, sex, and practice to 4 controls. The incidence of cardiovascular disease (CVD), stroke, end-stage renal failure (ESRF), cancer, osteoporosis, and infection were calculated per 1,000 person-years during the study period and compared to controls using Poisson regression to obtain incidence rate ratios (IRRs). IRRs were adjusted for baseline age, sex, body mass index, smoking status, alcohol intake, hypertension, hyperlipidemia, Charlson Index scores, and prednisolone use. Age- and sex-specific incidence rates were calculated. Results: When comparing the 7,732 prevalent cases of SLE with 28,079 matched controls, the unadjusted IRR was 1.98 (95% confidence interval [95% CI] 1.69–2.31) for CVD, 1.81 (95% CI 1.49–2.19) for stroke, 7.81 (95% CI 4.68–13.05) for ESRF, 1.28 (95% CI 1.17–1.40) for cancer, 2.53 (95% CI 2.27–2.82) for osteoporosis, and 1.49 (95% CI 1.40–1.58) for infection. After adjustment, the rates remained significantly higher in cases. Men with SLE had higher rates of CVD, stroke, and cancer, whereas women had higher rates of infection and osteoporosis. Those at younger ages were at the greatest relative risk compared with controls. Cases had significantly higher Charlson Index scores at baseline. Conclusion: People with SLE in the UK have a greater burden of comorbidity and are more likely to develop CVD, stroke, ESRF, cancer, osteoporosis, and infection than people of the same age and sex

    Prevention of Colorectal Neoplasia

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    Colorectal cancer (CRC) is one of the leading causes of cancer-related morbidity and mortality worldwide. There are well-established screening protocols involving fecal testing, radiographic, and endoscopic evaluations that have led to decreased incidence and mortality of CRC in the United States. In addition to screening for CRC, there is interest in preventing colorectal neoplasia by targeting the signaling pathways that have been identified in the pathway of dysplasia progressing to carcinoma. This review will detail the efficacy of multiple potential preventative strategies including lifestyle changes (physical activity, alcohol use, smoking cessation, and obesity); dietary factors (dietary patterns, calcium, vitamin D, fiber, folate, and antioxidants and micronutrients); and chemopreventive agents (nonsteroidal anti-inflammatory drugs, statins, metformin, bisphosphonates, and postmenopausal hormonal therapy)
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