2,217 research outputs found

    Std fimbriae-fucose interaction increases Salmonella-induced intestinal inflammation and prolongs colonization

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    Author summary The intestinal epithelium is a crucial biological interface, interacting with both commensal and pathogenic microorganisms. It’s lined with heavily glycosylated proteins and glycolipids which can act as both attachment sites and energy sources for intestinal bacteria. Fut2, the enzyme governing epithelial α1,2-fucosylation, has been implicated in the interaction between microbes and intestinal epithelial cells. Salmonella is one of the most important bacterial gastrointestinal pathogens affecting millions of people worldwide. Salmonella possesses fimbrial and non-fimbrial adhesins which can be used to adhere to host cells. Here we show that Salmonella expresses Std fimbriae in the gastrointestinal tract in vivo and exploit Std fimbriae to bind fucosylated structures in the mucus and on the intestinal epithelium. Furthermore, we demonstrate that the Std fimbriae-fucose interaction is necessary for bacterial colonization of the intestine and for triggering intestinal inflammation. These data lend new insights into bacterial adhesion-epithelial interactions which are essential for bacterial pathogenesis and key factors in determining tissue tropism and host susceptibility to infectious disease

    Intersecting Knowledge Fields and Integrating Data-Driven Computational Design en Route to Performance-Oriented and Intensely Local Architectures

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    This paper discusses research by design efforts in architectural education, focused on developing concepts and methods for the design of performance-oriented and intensely local architectures. The pursued notion of performance foregrounds the interaction between a given architecture and its local setting, with consequences not only for the design product but also for the related processes by which it is generated. Integrated approaches to data-driven computational design serve to generate such designs. The outlined approach shifts the focus of design attention away from the delivery of finite architectural objects and towards an expanded range of architecture-environment interactions that are registered, instrumentalised and modulated over time. This paper examines ongoing efforts in integrating specific architectural goals and approaches, computational data-driven design methods and generative design processes, based on a range of context-specific and often real-time data sets. The work discussed is produced in the context of the Research Centre for Architecture and Tectonics (RCAT) and the Advanced Computational Design Laboratory (ACDL) at the Oslo School of Architecture and Design

    Preventing Catastrophic Failure of Microfibrillar Adhesives in Compliant Systems Based on Statistical Analysis of Adhesive Strength

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    Adhesives based on fibrillar surface microstructures have shown great potential for handling applications requiring strong, reversible, and switchable adhesion. Recently, the importance of the statistical distribution of adhesive strength of individual fibrils in controlling the overall performance was revealed. Strength variations physically correspond to different interfacial defect sizes, which, among other factors, are related to surface roughness. For analysis of the strength distribution, Weibull's statistical theory of fracture was introduced. In this study, the importance of the statistical properties in controlling the stability of attachment is explored. Considering the compliance of the loading system, we develop a stability criterion based on the Weibull statistical parameters. It is shown that when the distribution in fibril adhesive strength is narrow, the global strength is higher but unstable detachment is more likely. Experimental variation of the loading system compliance for a specimen of differing statistical properties shows a transition to unstable detachment at low system stiffness, in good agreement with the theoretical stability map. This map serves to inform the design of gripper compliance, when coupled with statistical analysis of strength on the target surface of interest. Such a treatment could prevent catastrophic failure by spontaneous detachment of an object from an adhesive gripper. © 2021 The Authors. Published by American Chemical Society

    Aluminium extrusion analysis by the finite volume method

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    Present work proposes a novel numerical scheme to calculate stress and velocity fields of metal flow in axisymmetric extrusion process in steady state. Extrusion of aluminium is one main metal forming process largely applied in manufacturing bars and products with complex cross section shape. The upper-bound, slab, slip-line methods and more recently the numerical methods such as the Finite Element Method have been commonly applied in aluminium extrusion analysis. However, recently in the academy, the Finite Volume Method has been developed for metal flow analysis: literature suggests that extrusion of metals can be modelled by the flow formulation. Hence, metal flow can be mathematically modelled such us an incompressible non linear viscous fluid, owing to volume constancy and varying viscosity in metal forming. The governing equations were discretized by the Finite Volume Method, using the Explicit MacCormack Method in structured and collocated mesh. The MacCormack Method is commonly used to simulate compressible fluid flow by the finite volume method. However, metal plastic flow and incompressible fluid flow do not present state equations for the evolution of pressure, and therefore, a velocity-pressure coupling method is necessary to obtain a consistent velocity and pressure fields. The SIMPLE Method was applied to attain pressure-velocity coupling. This new numerical scheme was applied to forward hot extrusion process of an aluminium alloy. The metal extrusion velocity fields achieved fast convergence and a good agreement with experimental results. The MacCormack Method applied to metal extrusion produced consistent results without the need of artificial viscosity as employed by the compressible flow simulation approaches. Therefore, present numerical results also suggest that MacCormack method together with SIMPLE method can be applied in the solution of metal forming processes in addition to the traditional application for compressible fluid flow

    Generative AI in Idea Development: The Role of Numeric and Visual Feedback

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    Human creativity is a crucial factor in developing innovative ideas. Many ideas are being generated, but only a few receive feedback, as creating feedback is a costly and time-consuming effort in innovation. While feedback promises higher idea quality, previous work requires human experts with domain expertise. Generative AI could provide automated feedback and is expected to transform creative work. This short paper presents an experimental series in which we let humans collaborate with generative AI to develop ideas. Based on dual-coding and media synchronicity theory, we conceptualize numerical and visual feedback to overcome cognitive barriers. We manipulate feedback modalities and timing to personalize the interaction. Our contributions provide evidence on when and why specific co-creative arrangements between humans and generative AI are favorable

    Contact Aging Enhances Adhesion of Micropatterned Silicone Adhesives to Glass Substrates

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    The transfer of biological concepts into synthetic micropatterned adhesives has recently enabled a new generation of switchable, reversible handling devices. Over the last two decades, many design principles have been explored that helped to understand the underlying mechanics and to optimize such adhesives for certain applications. An aspect that has been overlooked so far is the influence of longer hold times on the adhesive contacts. Exemplarily, the pull‐off stress and work of separation of a micropatterned adhesive specimen are enhanced by factors 3 and 6, respectively, after 1000 min in contact with a glass substrate. In addition to such global measures, the increase of adhesion of all individual micropillars is analyzed. It is found that contact aging varied across the microarray, as it drastically depends on local conditions. Despite great differences on the micropillar scale, the adhesion of entire specimens increased with very similar power laws, as this is determined by the mean contact ageing of the individual structures. Overall, contact aging must be critically evaluated before using micropatterned adhesives, especially for long‐term fixations and material combinations that are chemically attractive to each other

    Dietary and serum tyrosine, white matter microstructure and inter-individual variability in executive functions in overweight adults: Relation to sex/gender and age

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    Tyrosine (tyr), the precursor of the neurotransmitter dopamine, is known to modulate cognitive functions including executive attention. Tyr supplementation is suggested to influence dopamine-modulated cognitive performance. However, results are inconclusive regarding the presence or strength and also the direction of the association between tyr and cognitive function. This pre-registered cross-sectional analysis investigates whether diet-associated serum tyr relates to executive attention performance, and whether this relationship is moderated by differences in white matter microstructure. 59 healthy, overweight, young to middle-aged adults (20 female, 28.3 ± 6.6 years, BMI: 27.3 ± 1.5 kg/m2) drawn from a longitudinal study reported dietary habits, donated blood and completed diffusion-weighted brain magnetic resonance imaging and the attention network test. Main analyses were performed using linear regressions and non-parametric voxel-wise inference testing. Confirmatory analyses did neither support an association between dietary and serum tyr nor a relationship between relative serum tyr/large neutral amino acids (LNAA) levels or white matter microstructure and executive attention performance. However, exploratory analyses revealed higher tyr intake, higher serum tyr and better executive attention performance in the male sex/gender group. In addition, older age was associated with higher dietary tyr intake and lower fractional anisotropy in a widespread cluster across the brain. Finally, a positive association between relative serum tyr/LNAA and executive attention performance was found in the male sex/gender group when accounting for age effects. Our analysis advances the field of dopamine-modulated cognitive functions by revealing sex/gender and age differences which might be diet-related. Longitudinal or intervention studies and larger sample sizes are needed to provide more reliable evidence for links between tyr and executive attention

    Trauma Therapy and The Need for Cross Cultural Competence

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    This project addresses the relevance of cross cultural competence for work in trauma therapy. I begin with a review of the literature on approaches to trauma therapy, identifying similarities and differences in key approaches, and comparing outcomes where that information is available. I then review a variety of cross cultural variations in mental health conditions and symptoms, attempting to roughly position each within the ethnic group or groups in which the variation is mostly likely to be found. Finally, I review the very small existing literature examining the impact of culturally sensitive approaches to trauma therapy in several non-Western ethnic groups. I conclude by highlighting the relevance of cross cultural competence for meeting the needs of patients with trauma from cultures around the globe, who must be considered in the context of their own cultural values, beliefs, and expectations in order to yield the greatest therapeutic effects
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