Synthetic mixed-signal computation in living cells

Living cells implement complex computations on the continuous environmental signals that they encounter. These computations involve both analogue- and digital-like processing of signals to give rise to complex developmental programs, context-dependent behaviours and homeostatic activities. In contrast to natural biological systems, synthetic biological systems have largely focused on either digital or analogue computation separately. Here we integrate analogue and digital computation to implement complex hybrid synthetic genetic programs in living cells. We present a framework for building comparator gene circuits to digitize analogue inputs based on different thresholds. We then demonstrate that comparators can be predictably composed together to build band-pass filters, ternary logic systems and multi-level analogue-to-digital converters. In addition, we interface these analogue-to-digital circuits with other digital gene circuits to enable concentration-dependent logic. We expect that this hybrid computational paradigm will enable new industrial, diagnostic and therapeutic applications with engineered cells.Fundacao para a Ciencia e a Tecnologia (Fellowship SFRH/BD/51576/2011)National Science Foundation (U.S.) (1350625)National Science Foundation (U.S.) (1124247)United States. Office of Naval Research (N000141310424)National Institutes of Health (U.S.) (New Innovator Award 1DP2OD008435)National Centers for Systems Biology (U.S.) (1P50GM098792

Small Orbits

We study both the "large" and "small" U-duality charge orbits of extremal black holes appearing in D = 5 and D = 4 Maxwell-Einstein supergravity theories with symmetric scalar manifolds. We exploit a formalism based on cubic Jordan algebras and their associated Freudenthal triple systems, in order to derive the minimal charge representatives, their stabilizers and the associated "moduli spaces". After recalling N = 8 maximal supergravity, we consider N = 2 and N = 4 theories coupled to an arbitrary number of vector multiplets, as well as N = 2 magic, STU, ST^2 and T^3 models. While the STU model may be considered as part of the general N = 2 sequence, albeit with an additional triality symmetry, the ST^2 and T^3 models demand a separate treatment, since their representative Jordan algebras are Euclidean or only admit non-zero elements of rank 3, respectively. Finally, we also consider minimally coupled N = 2, matter coupled N = 3, and "pure" N = 5 theories.Comment: 40 pages, 9 tables. References added. Expanded comments added to sections III. C. 1. and III. F.

A comparison between weakly-compressible smoothed particle hydrodynamics (WCSPH) and moving particle semi-implicit (MPS) methods for 3d dam-break flows

Lagrangian particle-based methods have opened new perspectives for the investigation of complex problems with large free-surface deformation. Some well-known particle-based methods adopted to solve non-linear hydrodynamics problems are the smoothed particle hydrodynamics (SPH) and the moving particle semi-implicit (MPS). Both methods modeled the continuum by a system of Lagrangian particles (points) but adopting distinct approaches for the numerical operators, pressure calculation, and boundary conditions. Despite the ability of the particle-based methods in modeling highly nonlinear hydrodynamics, some shortcomings, such as unstable pressure computation and high computational cost remains. In order to assess the performance of these two methods, the weaklycompressible SPH (WCSPH) parallel solver, DualSPHysics, and an in-house incompressible MPS solver are adopted in this work. Two test cases consisting of threedimensional (3D) dam-break problems are simulated, and wave heights, pressures and forces are compared with available experimental data. The influence of the artificial viscosity on the accuracy of WCSPH is investigated. Computational times of both solvers are also compared. Finally, the relative benefits of the methods for solving free-surface problems are discussed, therefore providing directions of their applicability.Comment: 26 pages, 12 figure

The demographics of decarbonizing transport: the influence of gender, education, occupation, age, and household size on electric mobility preferences in the Nordic region

Many researchers, policymakers and other stakeholders have explored and supported efforts to transition towards more sustainable forms of low-carbon mobility. Often, discussion will flow from a narrow view of consumer perceptions surrounding passenger vehicles—presuming that they act in rationalist, instrumental, and predictable patterns. In this paper, we hold that a better understanding of the social and demographic perceptions of electric vehicles (compared to other forms of mobility, including conventional cars) is needed. We provide a comparative and mixed methods assessment of the demographics of electric mobility and stated preferences for electric vehicles, drawing primarily on a survey distributed to more than 5,000 respondents across Denmark, Finland, Iceland, Norway and Sweden. We examine how gender influences preferences; how experience in the form of education and occupation shape preferences; and how aging and household size impact preferences. In doing so we hope to reveal the more complex social dynamics behind how potential adopters consider and calculate various aspects of conventional mobility, electric mobility, and vehicle-to-grid systems. In particular, our results suggest that predominantly men, those with higher levels of education in full time employment, especially with occupations in civil society or academia, and below middle age (30 to 45), are the most likely to buy them. However, our analysis also reveals other market segments where electric vehicles may take root, e.g. among higher income females and retirees/pensioners. Moreover, few respondents were orientated towards V2G, independent of their demographic attributes. Our empirical results can inform ongoing discussions about energy and transport policy, the drivers of environmental change, and deliberations over sustainability transitions

Beyond emissions and economics: rethinking the co-benefits of Nordic Electric Vehicles (EVs) and Vehicle-To-Grid (V2G)

Electric vehicles and vehicle-to-grid are one option to achieve the transition to decarbonizing society. Despite perceived advantages of cost-savings and carbon reductions, such technologies have faced various barriers that has prevented wide-scale adoption. While much literature has carefully investigated the techno-economics dimensions to electric mobility, we ask: what are the full set of benefits that EVs and V2G offer? To provide an answer, the authors conducted 227 semi-structured interviews with transportation and electricity experts from over 200 institutions across the Nordic region. Results show that there is an extensive range of benefits for both EVs and V2G, with experts suggesting 29 and 25 categories of benefits for EVs and V2G, respectively. Though the experts covered the obvious benefits of economic savings, emissions, and renewable energy integration, several other novel benefits were identified. The second and third most common discussed EV benefit was noise reduction and better performance, which are typically not widely discussed. Similarly we find that V2G benefits covered topics like vehicle-to-home and solar integration, as well as more novel benefits, like vehicle-to-telescope and emergency power backup. The article concludes with a discussion of future research and benefits in the context of energy research and analysis

Fusion within and between whorls of floral organs in Galipeinae (Rutaceae): structural features and evolutionary implications

Background and Aims Most genera of the neotropical Galipeinae (tribe Galipeeae, Rutoideae) exhibit several forms and degrees of fusion between the floral organs, including the union of petals into an apparently sympetalous corolla, the joining of the stamens among themselves and to the corolla, and the partial to complete connation of carpels. Though these and others floral traits are currently used in the circumscription of species in Galipeinae, few studies have shown in detail in which way (postgenital or congenital) and to what extent these fusions occur. To elucidate these anatomical conditions, a structural study of the flowers of the Galipeinae species was carried out. Methods Flowers of six species from three genera of Galipeinae were studied in their morphology, anatomy and development with stereomicroscopy, light microscopy and scanning electron microscopy (SEM). Key Results The floral tube is formed by synorganization of stamens with petals in all species, and exhibits three main patterns: (1) Conchocarpus heterophyllus and C. minutiflorus have a floral tube formed by marginal coherence/adherence of petals and filaments due to interwining trichomes (postgenital connection); (2) Erythrochiton brasiliensis has a tube formed by congenital fusion of petals and filaments; and (3) Galipea jasminiflora and Conchocarpus macrophyllus have a tube formed distally with the first pattern, and proximally with the second pattern. Although floral tubes seem to be homologous within Galipeinae, this is not true at the level of the family: the floral tube of Correa (from an only distantly related clade of the family) is formed by postgenital union of the petals representing a convergent structure. The gynoecium of the studied species of Galipeinae shows a great variability in the extent of fusion of carpel flanks. Even though different structures for the mature gynoecium were found in each genus, all genera show postgenitally fused carpel apices, which is related to the formation of a compitum, as described earlier for other members of Rutaceae. Conclusions The degree and diversity of fusions of floral organs in Galipeinae is unique within the order Sapindales. A study of the amount of diversification of Galipeinae in South America and comparison with other clades of Rutaceae would be of interes

Policy mechanisms to accelerate electric vehicle adoption: a qualitative review from the Nordic region

Electric vehicles are an important instrument to decarbonize transportation, offering a range of co-benefits such as reductions in local pollution, noise emissions, and oil dependency. Unfortunately, price, range, infrastructure and technological uncertainty are only some of the barriers to a faster adoption of these vehicles. To overcome these barriers, there is a broad call for public support and a growing body of primarily survey and choice experiment studies to show which policy mechanisms are effective, with mixed outcomes. In response, this paper offers a qualitative comparative analysis that draws on 227 semi-structured interviews with 257 transportation and electricity experts from 201 institutions across 17 cities within the Nordic region to discuss the reasoning and arguments behind EV incentives and policy mechanisms. A frequency analysis of the most coded responses favoured cost reduction mechanisms, in particular taxation exemptions; infrastructure support for public and apartment charging; the importance of consumer awareness, especially information campaigns; certain other specific policy measures like procurement programs and environmental zones; and more general policy principles. More in-depth, our analysis shows the debates around these mechanisms and how the pros and cons of these mechanisms differ per country, per transport segment, per phase of transition or market share, even per city. In short, this paper calls for strong stable national targets and price incentives combined with local flexibility to implement secondary benefits and more attention to awareness campaigns to advance the implementation of electric vehicles

Rethinking the spatiality of Nordic electric vehicles and their popularity in urban environments: moving beyond the city?

With a global transition to electric vehicles (EVs) slowly gaining traction, it is expedient to move the debate to issues connected to geography, space, and place. One of these emerging issues is the uptake of EVs in rural areas. This paper provides a spatial state of affairs in the Nordic region and it explores how EVs are perceived and argued to fit within rural-suburban-urban categories by users and potential adopters. To do so, it draws on a mix of original and secondary data: (1) a randomized survey among 4322 respondents, (2) 227 expert interviews, (3) eight focus groups conducted across Iceland, Denmark, Sweden, Finland and Norway, and (4) geographically mapped municipal level vehicle registrations across Norway and Sweden. This data shows that while the uptake primarily takes place in (sub)urban regions, EVs are used in rural environments, partly for self-sufficiency reasons. After acknowledging that individual choices and circumstances dictate final purchase decisions, the paper concludes that planners and researchers should be aware off and, if possible, prevent that a skewed urbanized popularity keeps people elsewhere from looking at EVs as a viable option

Reviewing Nordic transport challenges and climate policy priorities: expert perceptions of decarbonisation in Denmark, Finland, Iceland, Norway, Sweden

The five Nordic countries of Denmark, Finland, Iceland, Norway and Sweden have aggressive climate and energy policies in place and are largely on track in their decarbonisation of electricity, heat, and buildings. Transportation and mobility, however, remains a pressing challenge. This study asks: what are the greatest national and regional transport challenges facing Nordic countries? To provide an answer, the authors conducted 227 semi-structured interviews with participants from 201 institutions across seventeen cities within the Nordic region. Those interviewed represent a diverse array of stakeholders involved with transport technology, policy and practice. Although respondents identified 44 distinct transport challenges, the fossil fuel intensity of transport was by far the most frequently mentioned by than two-fifths (42%) of the expert sample. Five other challenges were also mentioned the most frequently by respondents: long travel distances (17%), the state of public transport infrastructure (16%), congestion (15%), population density (10%), and electrification of transport (10%). Interestingly, items such as costs and affordability, energy or transport efficiency, consumer knowledge and awareness, and automobile accidents were mentioned by only 3% (or less). The article concludes by what this heterogeneity and prioritization of challenges means for future Nordic research and policy

Promoting Vehicle to Grid (V2G) in the Nordic region: expert advice on policy mechanisms for accelerated diffusion

Vehicle to Grid (V2G) holds the promise of cheap, flexible, and fast-responding storage through the use of electric vehicle batteries. Unfortunately, infrastructure, battery degradation and consumer awareness are only some of the challenges to a faster development of this technology. This paper offers a qualitative comparative analysis that draws on a subsample of 227 semi-structured interviews on electric vehicles with both transportation and electricity experts from 201 institutions and 17 cities within the Nordic region to discuss the reasoning and arguments behind V2G incentives and policy mechanisms. A frequency analysis of the most coded V2G responses favoured an update of the electricity market regulation – in particular in relation to electricity taxation and aggregator markets – and support for pilot projects. However, the analysis overall implies that V2G, in contrast to EVs, is a technology for the market and by the market. One that will develop on its own over time. More in-depth, our analysis shows the debates around V2G and how its perspective differs per country, pending available frequency capacity and flexible production (hydro power). The paper calls for a further development of flexible electricity markets, support for pilot projects, and attention to information and planning