Experimental evolution gone wild

Because of their large population sizes and rapid cell division rates, marine microbes have, or can generate, ample variation to fuel evolution over a few weeks or months, and subsequently have the potential to evolve in response to global change. Here we measure evolution in the marine diatom Skeletonema marinoi evolved in a natural plankton community in CO₂-enriched mesocosms deployed in situ. Mesocosm enclosures are typically used to study how the species composition and biogeochemistry of marine communities respond to environmental shifts, but have not been used for experimental evolution to date. Using this approach, we detect a large evolutionary response to CO₂ enrichment in a focal marine diatom, where population growth rate increased by 1.3-fold in high CO₂-evolved lineages. This study opens an exciting new possibility of carrying out in situ evolution experiments to understand how marine microbial communities evolve in response to environmental change.     

A probabilistic framework for windows of opportunity: the role of temporal variability in critical transitions

The establishment of young organisms in harsh environments often requires a window of opportunity (WoO). That is, a short time window in which environmental conditions drop long enough below the hostile average level, giving the organism time to develop tolerance and transition into stable existence. It has been suggested that this kind of establishment dynamics is a noise-induced transition between two alternate states. Understanding how temporal variability (i.e. noise) in environmental conditions affects establishment of organisms is therefore key, yet not well understood or included explicitly in the WoO framework. In this paper, we develop a coherent theoretical framework for understanding when the WoO open or close based on simple dichotomous environmental variation. We reveal that understanding of the intrinsic timescales of both the developing organism and the environment is fundamental to predict if organisms can or cannot establish. These insights have allowed us to develop statistical laws for predicting establishment probabilities based on the period and variance of the fluctuations in naturally variable environments. Based on this framework, we now get a clear understanding of how changes in the timing and magnitude of climate variability or management can mediate establishment chances.     

Which games are growing bacterial populations playing?

Microbial communities display complex population dynamics, both in frequency and absolute density. Evolutionary game theory provides a natural approach to analyse and model this complexity by studying the detailed interactions among players, including competition and conflict, cooperation and coexistence. Classic evolutionary game theory models typically assume constant population size, which often does not hold for microbial populations. Here, we explicitly take into account population growth with frequency-dependent growth parameters, as observed in our experimental system. We study the in vitro population dynamics of the two commensal bacteria (Curvibacter sp. (AEP1.3) and Duganella sp. (C1.2)) that synergistically protect the metazoan host Hydra vulgaris (AEP) from fungal infection. The frequency-dependent, nonlinear growth rates observed in our experiments indicate that the interactions among bacteria in co-culture are beyond the simple case of direct competition or, equivalently, pairwise games. This is in agreement with the synergistic effect of anti-fungal activity observed in vivo. Our analysis provides new insight into the minimal degree of complexity needed to appropriately understand and predict coexistence or extinction events in this kind of microbial community dynamics. Our approach extends the understanding of microbial communities and points to novel experiments.     

Human exchange techniques for citizen participation in town revitalization

Citizen participation in design and planning can be regarded as one of the major social movements of the 1970s. Questions such as who should participate, how should they be involved, and when, are significant to designers. This paper illustrates one aspect of the participatory process: environmental awareness and how various human interaction techniques are used in different community settings. Small communities and urban neighbourhoods were selected because they have manageable scales for this type of human activity. Implicit in the examination of various participatory approaches is the recognition of an emerging new role for designers, that of structuring group efforts.     

汽车售后服务场景的用户体验设计研究

目的通过对具体的汽车售后服务场景中用户体验的深入剖析和研究,探究在服务设计中如何运用用户研究的方法和如何根据具体场景构建合理的用户研究方法论体系。方法通过在实践中运用各研究方法,验证各个方法在获取数据、洞察观点、建立设计逻辑等各个环节的作用。进而为在服务设计中,如何结合具体的服务场景合理运用用户研究方法,构建有效的研究体系提供建议。结果通过设计研究和实践验证得出在服务场景中有效的用户体验评测原则,及获取用户角色模型的推理方法。结论通过本次研究,获得在线下场景中根据场景的限制条件和需求,构建合理的方法和流程,对以后汽车售后服务系统的服务优化设计和体验设计提供良好的方法论。     

Dynamic Environmental Control in Microfluidic Single‐Cell Cultivations: From Concepts to Applications

Microfluidic single‐cell cultivation (MSCC) is an emerging field within fundamental as well as applied biology. During the last years, most MSCCs were performed at constant environmental conditions. Recently, MSCC at oscillating and dynamic environmental conditions has started to gain significant interest in the research community for the investigation of cellular behavior. Herein, an overview of this topic is given and microfluidic concepts that enable oscillating and dynamic control of environmental conditions with a focus on medium conditions are discussed, and their application in single‐cell research for the cultivation of both mammalian and microbial cell systems is demonstrated. Furthermore, perspectives for performing MSCC at complex dynamic environmental profiles of single parameters and multiparameters (e.g., pH and O₂) in amplitude and time are discussed. The technical progress in this field provides completely new experimental approaches and lays the foundation for systematic analysis of cellular metabolism at fluctuating environments.     

Rational spatio-temporal strategies for controlling a Chagas disease vector in urban environments

The rational design of interventions is critical to controlling communicable diseases, especially in urban environments. In the case of the Chagas disease vector Triatoma infestans, successful control is stymied by the return of the insect after the effectiveness of the insecticide wanes. Here, we adapt a genetic algorithm, originally developed for the travelling salesman problem, to improve the spatio-temporal design of insecticide campaigns against T. infestans, in a complex urban environment. We find a strategy that reduces the expected instances of vector return 34-fold compared with the current strategy of sequential insecticide application to spatially contiguous communities. The relative success of alternative control strategies depends upon the duration of the effectiveness of the insecticide, and it shows chaotic fluctuations in response to unforeseen delays in a control campaign. We use simplified models to analyse the outcomes of qualitatively different spatio-temporal strategies. Our results provide a detailed procedure to improve control efforts for an urban Chagas disease vector, as well as general guidelines for improving the design of interventions against other disease agents in complex environments.     

基于模块化理念的“15分钟社区生活圈”医养结合设施服务设计

目的 在老龄化社会和常态化疫情防控的背景下,针对社区设施建设提出一种模块化的15分钟社区生活圈医养结合设施服务设计。方法 基于模块化设计理念,以浙江省温州市为研究区域,通过调研走访,将社区医养设施划分为医疗模块、养老模块、防疫模块,并通过确定服务对象、选择服务内容、划分社区生活圈层级构建社区医养设施体系,为不同社区提供适合的医养结合设施设计方案。结果 以温州市锦园社区为例,提出了具体的15分钟社区生活圈医养结合设施设计方案,通过专家评审打分,结果显示所构建的设计方法具有合理性和可行性。结论 社区生活圈与医养设施的模块化设计模式,针对不同社区的医养需求,可以选择相应的医养模块单元进行组合配对,有利于提高社区医养结合设施规划的效率、社区医养服务能力和基层防疫应对能力。     

旅游导向型乡村社区导视系统策略研究

目的 探讨在乡村旅游快速发展的背景下,导视系统如何能够更好地为旅游导向型乡村社区进行服务。方法 结合具体案例成都幸福公社,通过实地调研分析社区现有导视系统存在的问题,探讨基于用户体验设计的导视系统如何满足新形态社区的需求,然后根据杰西·詹姆斯·加勒特关于用户体验设计的五个层面进行思考,提出升级优化的策略方案。结论 针对成都市幸福公社导视系统的优化策略方案包括区域的分割、节点布局的优化、导视系统具体的设计等探索。以求完善用户体验,更好地展现社区文化,丰富空间的用户体验从而保证社区的旅游热度;对其他旅游导向型乡村社区的导视系统设计研究或实践具有一定的启发意义。     

Characteristics of sulfide corrosion products on 316L stainless steel surfaces in the presence of sulfate-reducing bacteria

It has been found that microbial communities play a significant role in the corrosion process of steels exposed in aquatic and soil environments. Biomineralization influenced by microorganisms is believed to be responsible for the formation of corrosion products via complicated pathways of electron transfer between microbial cells and the metal. In this study, sulfide corrosion products were investigated for 316L stainless steel exposed to media with sulfate-reducing bacteria media for 7 weeks. The species of inorganic and organic sulfides in the passive film on the stainless steel were observed by epifluorescence microscope, environmental scanning electron microscope combined with energy dispersive spectroscopy and X-ray photoelectron spectroscopy. The transformation from metal oxides to metal sulfides influenced by sulfate-reducing bacteria is emphasized in this paper.     

Artificial Microbial Arenas: Materials for Observing and Manipulating Microbial Consortia

From the smallest ecological niche to global scale, communities of microbial life present a major factor in system regulation and stability. As long as laboratory studies remain restricted to single or few species assemblies, however, very little is known about the interaction patterns and exogenous factors controlling the dynamics of natural microbial communities. In combination with microfluidic technologies, progress in the manufacture of functional and stimuli‐responsive materials makes artificial microbial arenas accessible. As habitats for natural or multispecies synthetic consortia, they are expected to not only enable detailed investigations, but also the training and the directed evolution of microbial communities in states of balance and disturbance, or under the effects of modulated stimuli and spontaneous response triggers. Here, a perspective on how materials research will play an essential role in generating answers to the most pertinent questions of microbial engineering is presented, and the concept of adaptive microbial arenas and possibilities for their construction from particulate microniches to 3D habitats is introduced. Materials as active and tunable components at the interface of living and nonliving matter offer exciting opportunities in this field. Beyond forming the physical horizon for microbial cultivates, they will enable dedicated intervention, training, and observation of microbial consortia.     

The Role of Participation Architecture in Growing Sponsored Open Source Communities

Most research on open source software communities has focused on those that are community founded. More recently, firms have founded their own open source communities. How do sponsored open source communities differ from their autonomous counterparts? With comparative examination of 12 open source projects initiated by corporate sponsors, we identify three design parameters that together help form a participation architecture—the opportunity structure extended to potential external contributors. In exploring sponsors' community design decisions, we found that sponsored open source projects were more likely to offer transparency than they were accessibility and that this had implications for their communities' growth. We contribute theoretical constructs that offer a common basis of comparison for the future study of open source projects and illustrate how the tension between control and growth affects open source community design and creation.     

Constructor theory of life

Neo-Darwinian evolutionary theory explains how the appearance of purposive design in the adaptations of living organisms can have come about without their intentionally being designed. The explanation relies crucially on the possibility of certain physical processes: mainly, gene replication and natural selection. In this paper, I show that for those processes to be possible without the design of biological adaptations being encoded in the laws of physics, those laws must have certain other properties. The theory of what these properties are is not part of evolution theory proper, yet without it the neo-Darwinian theory does not fully achieve its purpose of explaining the appearance of design. To this end, I apply constructor theory''s new mode of explanation to express exactly within physics the appearance of design, no-design laws, and the logic of self-reproduction and natural selection. I conclude that self-reproduction, replication and natural selection are possible under no-design laws, the only non-trivial condition being that they allow digital information to be physically instantiated. This has an exact characterization in the constructor theory of information. I also show that under no-design laws an accurate replicator requires the existence of a ‘vehicle’ constituting, together with the replicator, a self-reproducer.     

Chemomechanics of complex materials: challenges and opportunities in predictive kinetic timescales

What do nanoscopic biomolecular complexes between the cells that line our blood vessels have in common with the microscopic silicate glass fiber optics that line our communication highways, or with the macroscopic steel rails that line our bridges? To be sure, these are diverse materials which have been developed and studied for years by distinct experimental and computational research communities. However, the macroscopic functional properties of each of these structurally complex materials pivots on a strong yet poorly understood interplay between applied mechanical states and local chemical reaction kinetics. As is the case for many multiscale material phenomena, this chemomechanical coupling can be abstracted through computational modeling and simulation to identify key unit processes of mechanically altered chemical reactions. In the modeling community, challenges in predicting the kinetics of such structurally complex materials are often attributed to the so-called rough energy landscape, though rigorous connection between this simple picture and observable properties is possible for only the simplest of structures and transition states. By recognizing the common effects of mechanical force on rare atomistic events ranging from molecular unbinding to hydrolytic atomic bond rupture, we can develop perspectives and tools to address the challenges of predicting macroscopic kinetic consequences in complex materials characterized by rough energy landscapes. Here, we discuss the effects of mechanical force on chemical reactivity for specific complex materials of interest, and indicate how such validated computational analysis can enable predictive design of complex materials in reactive environments.     

Environmental protection: researches in National Institute of Radiological Sciences

Some studies for radiological protection of the environment have been made at the National Institute of Radiological Sciences (NIRS). Transfer of radionuclides and related elements has been investigated for dose estimation of non-human biota. A parameter database and radionuclide transfer models have been also developed for the Japanese environments. Dose (rate)-effect relationships for survival, growth and reproduction have been investigated in conifers, Arabidopsis, fungi, earthworms, springtails, algae, duckweeds, daphnia and medaka. Also genome-wide gene expression analysis has been carried out by high coverage expression profiling (HiCEP). Effects on aquatic microbial communities have been studied in experimental ecosystem models, i.e., microcosms. Some effects were detected at a dose rate of 1 Gy day(-1) and were likely to arise from interspecies interactions. The results obtained at NIRS have been used in development of frameworks for environmental protection by some international bodies, and will contribute to environmental protection in Japan and other Asian countries.     

Performance of imaging systems analyzed with two-dimensional target

We have recently shown [Appl. Opt.51, 2739 (2012)] that performance analysis of optical imaging systems based on results obtained with classic one-dimensional (1D) resolution targets (such as the U.S. Air Force resolution target) are significantly different than those obtained with a newly proposed two-dimensional (2D) target. We hereby provide experimental evidence and show how the new 2D template can be used to correctly characterize optical imaging systems in terms of resolution and contrast. In particular, we apply the consequences of these observations to the optimal design of some 2D barcode structures.     

中国传统园林是环艺之母

自然,是人类生命的原点。中国传统园林是充满自然山水的诗意世界,是诗的空间、画的空间、虚幻的空间……在这些空间后面有着强大的诗、画,甚至神话的文本背景支持着文人们的筑园活动。艺术学体系下的环境艺术设计专业成立于1983年,宏观来看,包含室内外空间2大部分。2013年,教育部在专业目录上将其更名为环境设计。环艺设计是心物合一、哲匠互动的综合性学科,其本来目的旨在解决与人类情感和内心相关联的环境塑造问题,同时弥补了工科建筑学教育以技术和物体作为研究对象的欠缺。     

Accumulation of dead cells from contact killing facilitates coexistence in bacterial biofilms

Bacterial communities are governed by a wide variety of social interactions, some of which are antagonistic with potential significance for bacterial warfare. Several antagonistic mechanisms, such as killing via the type VI secretion system (T6SS), require killer cells to directly contact target cells. The T6SS is hypothesized to be a highly potent weapon, capable of facilitating the invasion and defence of bacterial populations. However, we find that the efficacy of contact killing is severely limited by the material consequences of cell death. Through experiments with Vibrio cholerae strains that kill via the T6SS, we show that dead cell debris quickly accumulates at the interface that forms between competing strains, preventing physical contact and thus preventing killing. While previous experiments have shown that T6SS killing can reduce a population of target cells by as much as 10⁶-fold, we find that, as a result of the formation of dead cell debris barriers, the impact of contact killing depends sensitively on the initial concentration of killer cells. Killer cells are incapable of invading or eliminating competitors on a community level. Instead, bacterial warfare itself can facilitate coexistence between nominally antagonistic strains. While a variety of defensive strategies against microbial warfare exist, the material consequences of cell death provide target cells with their first line of defence.     

Design and structural applications of stress-crack width relations in fibre reinforced concrete

The stress-crack width relationship has been shown to be the key to an understanding of fracture propagation in and mechanical behaviour in tension of fibre reinforced concrete materials and structures. A model is derived for the stress-crack width relationship for randomly oriented short fibre composites which takes hybrid fibre systems and possible fibre rupture into account. It is shown how this stress-crack width relationship can be included in a structural model for the prediction of crack widths in reinforced concrete structures. With this combination of models a rational design tool for the design of composite materials and structures has been established. It is shown how different fibre systems can be tested for structural applicability and how combined material and structural optimization can take place.     

A simple mix design method for structural lightweight aggregate concrete

Current design methods for structural lightweight aggregate concrete (SLWAC) are usually only valid for a limited range of concrete compositions that have previously been subjected to trial tests. The SLWAC mix design is more complex than that of normal weight concrete as more parameters need to be determined. Taking this into account, a simplified design method is proposed for SLWAC made with natural sand. The major advantages of the proposed method are that it is easy to apply and it can be generalized to any type of lightweight aggregate (LWA). For this, three additional design parameters are needed: the strength of LWA in concrete; the limit strength; the SLWAC potential strength. At most, two experimental mixtures are needed to determine these parameters. A biphasic model to estimate the strength of SLWAC is evaluated and high correlations are obtained. The good performance of the suggested method is demonstrated by examples of practical application and by the comparison with experimental results reported by the authors and other investigators.