12 research outputs found

    Imperfections: using defects to program designer matter

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    Errors are everywhere, and mechanical failures are especially common: buckled grain silos and cracked support columns are, justly, seen as an issue to be avoided. But flaws can also be used to design materials with unique functionalities. In the work presented here, we use two types of imperfections to create functional structures. First, we design materials that are locally stiff or soft, depending on how they are actuated, using topological imperfections: mistakes in their underlying architecture. Second, we create structures that shape-morph, because their individual elements fail, buckle, and snap- features that should be avoided otherwise.NWO-IBiological and Soft Matter Physic

    Topological defects produce exotic mechanics in complex metamaterials

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    Biological and Soft Matter Physic

    High resolution MRI for preoperative work-up of neonates with an anorectal malformation: a direct comparison with distal pressure colostography/fistulography

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    Objective: To compare MRI and colostography/fistulography in neonates with anorectal malformations (ARM), using surgery as reference standard. Methods: Thirty-three neonates (22 boys) with ARM were included. All patients underwent both preoperative high-resolution MRI (without sedation or contrast instillation) and colostography/fistulography. The Krickenbeck classification was used to classify anorectal malformations, and the level of the rectal ending in relation to the levator muscle was evaluated. Results: Subjects included nine patients with a bulbar recto-urethral fistula, six with a prostatic recto-urethral fistula, five with a vestibular fistula, five with a cloacal malformation, four without fistula, one with a H-type fistula, one with anal stenosis, one with a rectoperineal fistula and one with a bladderneck fistula. MRI and colostography/fistulography predicted anatomy in 88 % (29/33) and 61 % (20/33) of cases, respectively (p = 0.012). The distal end of the rectal pouch was correctly predicted in 88 % (29/33) and 67 % (22/33) of cases, respectively (p = 0.065). The length of the common channel in cloacal malformation was predicted with MRI in all (100 %, 5/5) and in 80 % of cases (4/5) with colostography/fistulography. Two bowel perforations occurred during colostography/fistulography. Conclusions: MRI provides the most accurate evaluation of ARM and should be considered a serious alternative to colostography/fistulography during preoperative work-up. Key Points: • High-resolution MRI is feasible without the use of sedation or anaesthesia. • MRI is more accurate than colostography/fistulography in visualising the type of ARM. • MRI is as reliable as colostography/fistulography in predicting the level of the rectal pouch. • Colostography/fistulography can be complicated by bowel perforation

    Global maps of soil temperature.

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    Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km <sup>2</sup> resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km <sup>2</sup> pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

    Selective buckling via states of self-stress in topological metamaterials.

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    Theoretical Physic

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    Hirschsprung disease (HSCR) is a complex genetic disease characterized by absence of ganglia in the intestine. HSCR etiology can be explained by a unique combination of genetic alterations: rare coding variants, predisposing haplotypes and Copy Number Variation (CNV). Approximately 18% of patients have additional anatomical malformations or neurological symptoms (HSCR-AAM). Pinpointing the responsible culprits within a CNV is challenging as often many genes are affected. Therefore, we selected candidate genes based on gene enrichment strategies using mouse enteric nervous system transcriptomes and constraint metrics. Next, we used a zebrafish model to investigate whether loss of these genes affects enteric neuron development in vivo. This study included three groups of patients, two groups without coding variants in disease associated genes: HSCR-AAM and HSCR patients without associated anomalies (HSCR-isolated). The third group consisted of all HSCR patients in which a confirmed pathogenic rare coding variant was identified. We compared these patient groups to unaffected controls. Predisposing haplotypes were determined, confirming that every HSCR subgroup had increased contributions of predisposing haplotypes, but their contribution was highest in isolated HSCR patients without RET coding variants. CNV profiling proved that specifically HSCR-AAM patients had larger Copy Number (CN) losses. Gene enrichment strategies using mouse enteric nervous system transcriptomes and constraint metrics were used to determine plaus
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