Inferring a Property of a Large System from a Small Number of Samples

Inferring the value of a property of a large stochastic system is a difficult task when the number of samples is insufficient to reliably estimate the probability distribution. The Bayesian estimator of the property of interest requires the knowledge of the prior distribution, and in many situations, it is not clear which prior should be used. Several estimators have been developed so far in which the proposed prior us individually tailored for each property of interest; such is the case, for example, for the entropy, the amount of mutual information, or the correlation between pairs of variables. In this paper, we propose a general framework to select priors that is valid for arbitrary properties. We first demonstrate that only certain aspects of the prior distribution actually affect the inference process. We then expand the sought prior as a linear combination of a one-dimensional family of indexed priors, each of which is obtained through a maximum entropy approach with constrained mean values of the property under study. In many cases of interest, only one or very few components of the expansion turn out to contribute to the Bayesian estimator, so it is often valid to only keep a single component. The relevant component is selected by the data, so no handcrafted priors are required. We test the performance of this approximation with a few paradigmatic examples and show that it performs well in comparison to the ad-hoc methods previously proposed in the literature. Our method highlights the connection between Bayesian inference and equilibrium statistical mechanics, since the most relevant component of the expansion can be argued to be that with the right temperature.

Life Cycle and Techno-Economic Assessment Templates for Emerging Carbon Management Technologies

Technologies that valorize carbon dioxide are becoming an increasingly relevant component of the portfolio of solutions necessary to mitigate and reverse climate change. Assessing the environmental and economic characteristics of these technologies early in their developmental trajectories can help technologists either efficiently accelerate emissions reductions and commercialization or realize potential infeasibility and direct resources toward better opportunities. To aid in such assessments, this article constructs a typology of carbon removal and utilization technologies and identifies specific pathways in need of early-stage life cycle assessment (LCA) and techno-economic assessment (TEA) templates. Based on published literature and project experience, example LCA and TEA templates are developed for high-priority pathways with relatively low technology readiness levels including direct air capture, chemical synthesis, algae products, carbonated concrete, and carbonated aggregates. The templates attempt to capture the most important elements of early-stage LCA and TEA in an easily understandable and usable manner that still allows for reliable, order-of-magnitude estimations and hotspot analysis. Opportunities for other practitioners to use and build upon the templates are also discussed.

Interstellar Objects Follow the Collapse of Molecular Clouds

Interstellar objects (ISOs), the parent population of 1i/‘Oumuamua and 2i/Borisov, are abundant in the interstellar medium of the Milky Way. This means that the interstellar medium, including molecular-cloud regions, has three components: gas, dust, and ISOs. From observational constraints of the field density of ISOs drifting in the solar neighborhood, we infer that a typical molecular cloud of 10 pc diameter contains some 1018 ISOs. At typical sizes ranging from hundreds of meters to tens of kilometers, ISOs are entirely decoupled from the gas dynamics in these molecular clouds. Here we address the question of whether ISOs can follow the collapse of molecular clouds. We perform low-resolution simulations of the collapse of molecular clouds containing initially static ISO populations toward the point where stars form. In this proof-of-principle study, we find that the interstellar objects definitely follow the collapse of the gas—and many become bound to the new-forming numerical approximations to future stars (sinks). At minimum, 40% of all sinks have one or more ISO test particles gravitationally bound to them for the initial ISO distributions tested here. This value corresponds to at least 1010 actual ISOs being bound after three initial freefall times. Thus, ISOs are a relevant component of star formation. We find that more massive sinks bind disproportionately large fractions of the initial ISO population, implying competitive capture of ISOs. Sinks can also be solitary, as their ISOs can become unbound again—particularly if sinks are ejected from the system. Emerging planetary systems will thus develop in remarkably varied environments, ranging from solitary to richly populated with bound ISOs.

Progress of EASICS Validation Experiments and Code Comparison of R5, RCC-MRX and ASME III Division V

The “Establishing AMR Structural Integrity Codes and Standards for UK GDA” (EASICS) project was established in 2019 to help support the acceptance of Advanced Modular Reactors, or AMRs, which are typically based on high temperature Generation IV reactors. The EASICS project is aiming to provide guidance on the requirements for codes and standards for the design of AMRs for use in the UK, to ensure that state-of-the art knowledge will be brought to bear on developing the required design and assessment methodologies. The EASICS project started in July 2019 and is looking to complete by December 2021. To support this aim, the work presented in this paper provides an overview of two interacting aspects of the programme. The first is to perform validation tests for high temperature creep-fatigue assessments of a plant relevant component. The second aspect is to use these results, to provide a comparison of internationally recognised approaches for the assessment of high temperature (creep regime) components. This approach will be repeated for two other case scenarios deemed to be plant relevant components. This paper builds upon the initial overview paper presented at the 2020 conference providing an update on progress. One of the cases presented herein, described as the Thin Walled Welded Pipe Test uses specialist testing of a plant relevant component under high temperature loading conditions is underway with some initial results available. The validation testing includes both fatigue tests and creep-fatigue tests on 316H welded thin section tubes. The tubes have been subjected to strain-controlled tension/compression (R-ratio of −1), with some including a displacement controlled dwell. The tests are being conducted at 525°C. An update to the progress of these tests is included herein. To help enhance interaction with the code bodies, and to understand the impact of differences in the approaches, comparative assessments have been performed when adopting R5, ASME Section III Div 5 and RCC-MRx. One comparison will be based around the tests detailed above (tube test). A further assessment comparison will consider the Evasion mock-up tests provided by CEA (sodium based thermal shock tests). The third assessment case is loosely based around a plant relevant assessment within one of the UK Advanced Gas Reactors (AGRs). This paper provides an overview of the results from all these cases using R5, ASME Section III Div 5 and RCC-MRx. The subsequent discussions covers results, differences and potential impact to the codes which will all help to inform a guidance document to support assessing AMRs within a UK regulatory framework.

Decomposition and optimization of linear structures using meta models

Monolithic optimization of large mechanical systems can be expensive and cumbersome. Drivers of computational cost and integration effort are, e.g., the size of the design problem and the number of different components, models, and disciplines. Distributed optimization schemes decompose large problems into smaller subproblems; however, they typically require intense coordination effort. This paper proposes an approach for complete decoupling by decomposing a monolithic optimization into independent optimization subproblems that can be solved without need for coordination. This is accomplished by sampling the space of component performance, here represented by eigenvalues and eigenvectors of stiffness matrices, and establishing meta models that map the relevant component performance values onto feasibility and mass estimates. The optimization procedure consists of two steps: First, a system optimization problem is solved by assigning stiffness requirements to components that are approximately feasible and mass-optimal. Second, the component optimization problems are solved independently of each other such that stiffness requirements are satisfied. As information on feasibility and mass is provided during system optimization by meta models, the approach will be referred to as informed decomposition. The effectiveness of the approach is demonstrated by minimizing the mass of a simple two-component linear structure subject to a requirement on total stiffness. This is done for three different component models, a beam with constant cross-section, a beam with varying cross-sections, and an arbitrary 2-dimensional body, using parametric and topology optimization, respectively. The approach produces results that are at most 1 % heavier than the results obtained by monolithic optimization.

Preposition Pied Piping and Stranding in Academic and Popular Nigerian English Writing

This paper examined preposition pied piping and stranding in academic and popular Nigerian English writing with a view to determining their pattern of occurrence. Preposition placement has not been studied in Nigerian English and in specific genres. The 160 246-word relevant component of ICE-Nigeria was the sub-corpus used, and the Systemic Theory guided the study. Analysed using a multi-layered qualitative approach, the data comprised 112 cases of pied piping, 64 of stranding and 4 of doubling. Pied piping was dominant over stranding in Academic Writing (78 percent v 22 percent), and stranding was 1.7 times more frequent in Popular Writing than in Academic Writing. Though evenly distributed in Popular Writing (44 each), pied piping was about twice as frequent as stranding in Popular Natural Sciences while stranding was virtually non-existent in Academic Natural Sciences. Whereas to-infinitive and passive clauses were stranding favourite sites (21 and 15 respectively), only in wh-relative clauses did pied piping operate and in which was the prominent sequence. In Academic Writing prepositions were pied-piped and stranded at an average of 3.83 and 1.82 per form respectively, but the rates were 3.31 and 3.1 in Popular Writing. Whereas in was the most pied-piped preposition and was 5.2 times more likely to be pied-piped than stranded, up was the most stranded form and its stranding relative to pied piping was infinitely more. Subtle differences in the genres’ degree of formality explain the disparities in the distribution of pied piping and stranding in the sub-corpus analysed.

From driverless dilemmas to more practical commonsense tests for automated vehicles

For the first time in history, automated vehicles (AVs) are being deployed in populated environments. This unprecedented transformation of our everyday lives demands a significant undertaking: endowing complex autonomous systems with ethically acceptable behavior. We outline how one prominent, ethically relevant component of AVs—driving behavior—is inextricably linked to stakeholders in the technical, regulatory, and social spheres of the field. Whereas humans are presumed (rightly or wrongly) to have the “common sense” to behave ethically in new driving situations beyond a standard driving test, AVs do not (and probably should not) enjoy this presumption. We examine, at a high level, how to test the common sense of an AV. We start by reviewing discussions of “driverless dilemmas,” adaptions of the traditional “trolley dilemmas” of philosophy that have sparked discussion on AV ethics but have limited use to the technical and legal spheres. Then, we explain how to substantially change the premises and features of these dilemmas (while preserving their behavioral diagnostic spirit) in order to lay the foundations for a more practical and relevant framework that tests driving common sense as an integral part of road rules testing.

ADAM10 hyperactivation acts on piccolo to deplete synaptic vesicle stores in Huntington’s disease

Synaptic dysfunction and cognitive decline in Huntington’s disease (HD) involve hyperactive A disintegrin and metalloproteinase domain-containing protein 10 (ADAM10). To identify the molecular mechanisms through which ADAM10 is associated with synaptic dysfunction in HD, we performed an immunoaffinity purification-mass spectrometry (IP-MS) study of endogenous ADAM10 in the brains of wild-type and HD mice. In the normal brain, proteins implicated in synapse organization, synaptic plasticity, and vesicle and organelles trafficking interact with ADAM10, suggesting that it may act as a hub protein at the excitatory synapse. Importantly, the ADAM10 interactome is enriched in presynaptic proteins and ADAM10 coimmunoprecipitates with piccolo (PCLO), a key player in the recycling and maintenance of synaptic vesicles (SVs). In contrast, reduced ADAM10/PCLO immunoprecipitation occurs in the HD brain, with decreased density of SVs in the reserve and docked pool at the HD presynaptic terminal. Conditional heterozygous deletion of ADAM10 in the forebrain of HD mice reduces active ADAM10 to wild-type level, and normalizes ADAM10/PCLO complex formation and SVs density and distribution. The results indicate that presynaptic ADAM10 and PCLO are a relevant component of HD pathogenesis.

Overview on Well-being Theories and the Role of Individual Responsibility

This paper aims to make a theoretical review on the main approaches to Well-being and also introduce the subject of Responsibility as an element to be considered in this discussion. Thus, three theories of well-being are presented: the Mainstream Economics, the Happiness Economics and The Capability Approach. Each of them provides considerations about what matters for people’s life and social development. However, none of them contemplates individual responsibility as a relevant component for development. And only The Capability Approach takes account of responsibility, but without furthering the subject. In this sense, the theme of responsibility is defended as having an important role for development and well-being, and could be incorporated by The Capability Approach.