Gene Drives on the Horizon National Academies of Sciences, Engineering, and Medicine; Division on Earth and Life Studies; Board on Life Sciences ...
06/2016
eBook
Odprti dostop
Research on gene drive systems is rapidly advancing. Many proposed applications of gene drive research aim to solve environmental and public health challenges, including the reduction of poverty and ...the burden of vector-borne diseases, such as malaria and dengue, which disproportionately impact low and middle income countries. However, due to their intrinsic qualities of rapid spread and irreversibility, gene drive systems raise many questions with respect to their safety relative to public and environmental health. Because gene drive systems are designed to alter the environments we share in ways that will be hard to anticipate and impossible to completely roll back, questions about the ethics surrounding use of this research are complex and will require very careful exploration.
Gene Drives on the Horizon outlines the state of knowledge relative to the science, ethics, public engagement, and risk assessment as they pertain to research directions of gene drive systems and governance of the research process. This report offers principles for responsible practices of gene drive research and related applications for use by investigators, their institutions, the research funders, and regulators.
During a severe loss of coolant accident in a nuclear reactor, steam and hydrogen are produced by the oxidation of reactor core and get distributed in the containment. A water spray system is ...employed to cool the mixture as well as to enhance the mixing of the gases to avoid hydrogen accumulation. This paper presents two-phase numerical simulations of transient vaporization of a moving spherical water droplet. The numerical model considers the variation of thermo-physical properties in both liquid- and vapor-phases, as functions of temperature and species concentrations. Multi-component diffusion and surface tension effects are also considered. The model has been validated using experimental results available in literature for hydrocarbon fuel droplet evaporation. Validated model is used to study the evaporation characteristics of moving water droplets under conditions typically observed in nuclear reactor during a loss of coolant accident. The effects of ambient temperature and hydrogen concentration on the vaporization characteristics are studied thoroughly.
This paper presents a distributed adaptive finite-time control solution to the formation-containment problem for multiple networked systems with uncertain nonlinear dynamics and directed ...communication constraints. By integrating the special topology feature of the new constructed symmetrical matrix, the technical difficulty in finite-time formation-containment control arising from the asymmetrical Laplacian matrix under single-way directed communication is circumvented. Based upon fractional power feedback of the local error, an adaptive distributed control scheme is established to drive the leaders into the prespecified formation configuration in finite time. Meanwhile, a distributed adaptive control scheme, independent of the unavailable inputs of the leaders, is designed to keep the followers within a bounded distance from the moving leaders and then to make the followers enter the convex hull shaped by the formation of the leaders in finite time. The effectiveness of the proposed control scheme is confirmed by the simulation.
Display omitted
•Understanding of the enzyme immobilization is required to optimize the processes.•Immobilization parameters and courses become critical to understand the process.•Changes in enzyme ...properties during immobilization can complicate the calculations.•Likely artifacts and problems to make these calculations are discussed.•Some advices to improve the understanding of immobilization processes are given.
Biocatalytic processes continue to find increasing application in industry. Therefore enzyme immobilization has also become of increasing importance as a means of allowing enzyme containment within reactors operating in continuous mode or else separation of enzyme after use in (fed-)batch reactors, as well as potential recycle. Whilst much has been reported in the scientific literature about enzyme immobilization methods, in many cases the protocol leads to losses in enzyme activity. In this review we outline the reasons for loss of activity during immobilization and highlight suitable diagnostic tests to elucidate the precise cause and thereby methods to restore activity. The need for standardized reporting of immobilization methods is also emphasized as a means of benchmarking alternative approaches.
The term Indo-Pacific has enjoyed growing popularity for years as a geographical and strategic construct. Increasingly, the Indo-Pacific is not conceived merely as a geographical construct, but also ...as a vital alternative to the Chinese “Belt and Road” Initiative (BRI). Conversely, Beijing views the debates over the Indo-Pacific as nothing more than an anti-Chinese containment strategy. Chinese criticism notwithstanding, the debate on the Indo-Pacific has gained traction within Europe, too. France promoted its own Indo-Pacific concept from 2018 onwards, followed by Germany in 2020 with their own Indo-Pacific Leitlinien (guidelines) that preceded the launch of the EU’s own Indo-Pacific strategy in 2021. To assess possible focus points of an emerging EU approach to the Indo-Pacific, this article evaluates strategic convergence and divergence between the so-called E2, France and Germany. It finds that Germany and France, despite their different role conceptions, converge with regard to their key objectives, planned initiatives and conceptualisations of regional order. The article also finds, however, that these contain, for the most part, very general declarations of interests and intent while also foregoing concrete strategic choices. It argues that any future EU approach to the Indo-Pacific is therefore likely to emerge around the least common denominator focus points, drawing on long-established EU approaches towards the Asia-Pacific, rather than a new, clear-cut EU approach to the Indo-Pacific.
•Hierarchized Local Sensitivity Analysis & Polynomial Chaos Expansion for structural modelling.•Application and validation based on an experimental Nuclear Containment Building.•Classification of ...influential parameters and phenomena affecting ageing structures.•Blind prediction of the structural behavior within a probabilistic framework at low cost.
This work proposes a global Stochastic Finite Element Method (SFEM) to model the effects of concrete ageing uncertainties on the serviceability and durability of large reinforced and prestressed structures with a containment role. As their modelling requires strongly non-linear, coupled and expensive calculations with a large number of parameters, adapted and efficient probabilistic strategies need to be defined aiming at a stochastic analysis within a reasonable cost and a physically admissible representativeness. In this contribution, this is achieved through four steps: (a) the definition of a well-established physical framework based on a staggered Thermo-Hydro-Mechanical + Leakage (THM-L) model; (b) the limitation of random inputs for uncertainty propagation to the most influential ones using a variance-based Hierarchized and Local Sensitivity Analysis (HLSA); (c) the construction of a THM-L response metamodel using Polynomial Chaos Expansion (PCE); (d) the reliability analysis of serviceability criteria using Crude Monte Carlo Method (CMCM) applied to the developed metamodel. For validation purposes and demonstration of achievability within a complex industrial framework, this global methodology is applied to an experimental 1:3 scaled Containment Building of a nuclear reactor. Eventually, it is shown that a complete probabilistic analysis of a physically admissible total dry air leakage rate (indicative of a nuclear containment structure’s performance) and its evolution in time are obtained within a computational time of tens of days only. Such result can provide insights and help during the decision-making process for the design, maintenance and risk assessment of large structures. For Nuclear Containment Buildings (NCB), a direct application would be the evaluation of lifespan extension based on a leakage-rate-defined criterion under operational loads.
•Effective heat capacity method simulates the PCM melting well.•Heat absorption mechanism of the PCM condenser is discussed.•PCM condenser design is optimized for nuclear safety.•Containment analysis ...is conducted when PCM condenser is used for passive cooling.•Performance of PCM condenser is evaluated compared to active spray system.
The new application of phase change material for passively cooling the containment building of a nuclear power plant provides many benefits such as minimized wall penetration, low maintenance cost, and the possibility of installation in currently operating power plants with a minimal design change. In this study, the applicability of PCM as a passive containment cooling system is verified through design and evaluation of the PCM condenser. In addition, the effective heat capacity method is verified for simulating the melting process of PCM in the condition of a reactor accident. The PCM condenser design is optimized with five design parameters; melting point, volume, heat transfer area, effective thermal conductivity, and total heat absorbed. The performance of the PCM condenser is evaluated by containment safety analysis and is compared to that of an active containment cooling system. Although the PCM condenser had a limitation for absorbing only a fixed amount of thermal energy due to the absence of an external heat sink, the PCM condenser shows better performance in the early stage after the accident initiation compared to the single spray system and finally maintains the integrity of the containment building.
Understanding the processes and mechanisms of the spatial spread of epidemics is essential for making reasonable judgments on the development trends of epidemics and for adopting effective ...containment measures. Using multi-agent network technology and big data on population migration, this paper constructed a city-based epidemic and mobility model (CEMM) to stimulate the spatiotemporal of COVID-19. Compared with traditional models, this model is characterized by an urban network perspective and emphasizes the important role of intercity population mobility and high-speed transportation networks. The results show that the model could simulate the inter-city spread of COVID-19 at the early stage in China with high precision. Through scenario simulation, the paper quantitatively evaluated the effect of control measures “city lockdown” and “decreasing population mobility” on containing the spatial spread of the COVID-19 epidemic. According to the simulation, the total number of infectious cases in China would have climbed to 138,824 on February 2020, or 4.46 times the real number, if neither of the measures had been implemented. Overall, the containment effect of the lockdown of cities in Hubei was greater than that of decreasing intercity population mobility, and the effect of city lockdowns was more sensitive to timing relative to decreasing population mobility.
•A city-based epidemic and mobility model is proposed for simulating the spatial spread of an epidemic between cities.•The effect of “city lockdowns” and “decreasing population mobility” measures were evaluated under ten scenarios.•The effect of decreasing returns to scale and distance decay of population mobility on the epidemic spread were found.
•Field test of two air-cooled data centers in different regions is conducted.•Power usage effectiveness of data center in semi-humid region is 1.21.•Data center employing indirect evaporative cooling ...achieves free cooling yearly.•Data center’s power usage effectiveness for annual free cooling can slump to 1.16.•Cooling systems consume 13.9% and 13.7% of total energy in two data centers.
Global data center electricity consumption constitutes 0.9–1.3 % of total demand, contributing to the importance of energy saving and waste heat recovery. A field test was conducted on two air-cooled data centers to assess their energy consumption and cooling system performance, providing valuable support for optimization. Power usage effectiveness (PUE) collected during peak summer conditions of conventional data center 1 varied from 1.274 to 1.291, with an extrapolated annual average of 1.2118. Analysis of energy consumption distribution indicated that information technology (IT) servers accounted for 78 % of the usage, followed by the cooling system at 13.9 %, the electrical system at 3.6 %, and auxiliary systems at 4.5 %. In contrast, data center 2, which relies on a year-round free cooling approach using indirect evaporative chillers, achieved an average PUE of 1.26 and allocated 13.8 % of its energy consumption to cooling. Notwithstanding, the efficiency of its cooling system is notably compromised by inadequate cold aisle containment and the scaling in the cooling water system. Post-optimization improvements are projected to reduce data center 2′s PUE to 1.155. Both data centers suffer from prevalent issues such as suboptimal IT load rates, improper segregation of hot and cold airflows within server rooms, and compromised cooling water quality.
PDF
