An Empirical Investigation of System Changes to Frame Links between Design Decisions and Ilities

Maintaining system performance in the presence of uncertainties in design and operating environments is both challenging and increasingly essential as system lifetimes grow longer. In response to perturbations brought on by these uncertainties, such as disturbances, context shifts, and shifting stakeholder needs, systems can continue to deliver value by being either robust or changeable. These lifecycle properties, sometimes called “ilities”, have been proposed as means to achieve system value sustainment in spite of changes in contexts or needs. Intentionally designing for these lifecycle properties is an active area of research, and no consensus has formed regarding how these and other “ilities” might trade off. This paper describes ongoing research that investigates empirical examples of system changes in order to characterize these changes and to develop a categorization scheme for framing and clarifying design approaches for proactively creating ilities in a system. Example categories from the data for system changes include: the perturbation trigger for the change, the type of agent executing the system change, and the valid lifecycle phase for execution. In providing a structured means to identify system change characteristics, this paper informs future research by framing possible relationships between ilities and design choices that enable them.Massachusetts Institute of Technology. Systems Engineering Advancement Research Initiativ

Quantum-enhanced metrology with the single-mode coherent states of an optical cavity inside a quantum feedback loop

In this paper, we use the nonlinear generator of dynamics of the individual quantum trajectories of an optical cavity inside an instantaneous quantum feedback loop to measure the phase shift between two pathways of light with a precision above the standard quantum limit. The feedback laser provides a reference frame and constantly increases the dependence of the state of the resonator on the unknown phase. Since our quantum metrology scheme can be implemented with current technology and does not require highly efficient single photon detectors, it should be of practical interest until highly entangled many-photon states become more readily available

Adult attachment, worry and reassurance seeking: Investigating the role of intolerance of uncertainty

Background: The adult attachment dimension of attachment anxiety has been demonstrated to be associated with a variety of anxiety symptomology, including worry, intolerance of uncertainty (IU) and reassurance seeking. A variety of research has indicated that IU is associated with level of worry and reassurance seeking. The relationships between attachment anxiety, worry, IU and threat-related reassurance seeking have not been subject to investigation. The present article reports the results of an investigation of these variables within a community sample.Methods: Three-hundred and twenty-eight participants were recruited to complete an online survey in which participants completed the Intolerance of Uncertainty Scale, the Experiences in Close Relationships Scale-Revised, the Penn State Worry Questionnaire and the Threat-related Reassurance Seeking Scale.Results:Attachment anxiety, IU and worry were correlated with threat-related reassurance seeking. Consistent with previous research, IU was found to mediate the relationship between attachment anxiety and worry. IU and worry were found to be serial-multiple mediators in the relationship between attachment anxiety and threat-related reassurance seeking.Conclusions:The results of the study suggest IU is likely to play a key role in the relationship between attachment anxiety and worry, as well as the relationship between attachment anxiety and threat-related reassurance seeking

X-ray Spectroscopy at the SuperXAS and Debye Beamlines: from in situ to Operando

Understanding structure–performance relationships are essential for the rational design of new functional materials or in the further optimization of (catalytic) processes. Due to the high penetration depth of the radiation used, synchrotron-based hard X-ray techniques (with energy > 4.5 keV) allow the study of materials under realistic conditions (in situ and operando) and thus play an important role in uncovering structure-performance relationships. X-ray absorption and emission spectroscopies (XAS and XES) give insight into the electronic structure (oxidation state, spin state) and local geometric structure (type and number of nearest neighbor atoms, bond distances, disorder) up to ~5 Å around the element of interest. In this mini review, we will give an overview of the in situ and operando capabilities of the SuperXAS beamline, a facility for hard X-ray spectroscopy, through recent examples from studies of heterogeneous catalysts, electrochemical systems, and photoinduced processes. The possibilities for time-resolved experiments in the time range from ns to seconds and longer are illustrated. The extension of X-ray spectroscopy at the new Debye beamline combined with operando X-ray scattering and diffraction and further developments of time-resolved XES at SuperXAS will open new possibilities after the Swiss Light Source upgrade mid 2025

Construction of bosonic string theory on infinitely curved Anti-de Sitter space

Free scalar field theory in the sector with a large number of particles can be interpreted as bosonic string theory on anti-de Sitter space of vanishing radius. Different ways of writing the field theory Hamiltonian translate to different ways of reparametrizing the world-sheet sigma coordinate. Adding a mass term in the field theory corresponds to cutting off the warped AdS direction, with cut-off inversely proportional to the mass. The string theory has neither tachyon, nor critical dimension.Comment: 18 pages, latex, using revte

Negotiating the inhuman: Bakhtin, materiality and the instrumentalization of climate change

The article argues that the work of literary theorist Mikhail M. Bakhtin presents a starting point for thinking about the instrumentalization of climate change. Bakhtin’s conceptualization of human–world relationships, encapsulated in the concept of ‘cosmic terror’, places a strong focus on our perception of the ‘inhuman’. Suggesting a link between the perceived alienness and instability of the world and in the exploitation of the resulting fear of change by political and religious forces, Bakhtin asserts that the latter can only be resisted if our desire for a false stability in the world is overcome. The key to this overcoming of fear, for him, lies in recognizing and confronting the worldly relations of the human body. This consciousness represents the beginning of one’s ‘deautomatization’ from following established patterns of reactions to predicted or real changes. In the vein of several theorists and artists of his time who explored similar ‘deautomatization’ strategies – examples include Shklovsky’s ‘ostranenie’, Brecht’s ‘Verfremdung’, Artaud’s emotional ‘cruelty’ and Bataille’s ‘base materialism’ – Bakhtin proposes a more playful and widely accessible experimentation to deconstruct our ‘habitual picture of the world’. Experimentation is envisioned to take place across the material and the textual to increase possibilities for action. Through engaging with Bakhtin’s ideas, this article seeks to draw attention to relations between the imagination of the world and political agency, and the need to include these relations in our own experiments with creating climate change awareness

Structural dynamics in Ni–Fe catalysts during CO₂ methanation - role of iron oxide clusters

Bimetallic Ni–Fe catalysts show great potential for CO$_{2}$ methanation concerning activity, selectivity and long-term stability even under transient reaction conditions as required for Power-to-X applications. Various contrary suggestions on the role of iron in this system on CO$_{2}$ activation have been proposed, hence, its actual task remained still unclear. In this study, we used X-ray absorption spectroscopy (XAS) combined with X-ray diffraction (XRD), XAS in combination with modulation excitation spectroscopy (MES) and density functional theory (DFT) to shed detailed light on the role of iron in a bimetallic Ni–Fe based CO$_{2}$ methanation catalyst. During catalyst activation we observed a synergistic effect between nickel and iron that led to higher fractions of reduced nickel compared to a monometallic Ni-based catalyst. By XAS–XRD combined with DFT, we found formation of FeO$_{x}$ clusters on top of the metal particles. Modulation excitation coupled XAS data complemented with DFT calculations provided evidence of a Fe$^{0}$ ⇌ Fe$^{2+}$+ ⇌ Fe$^{3+}$ redox mechanism at the interface of these FeO$_{x}$ clusters. This may promote CO$_{2}$ dissociation. This is the first time that this highly dynamic role of iron has been experimentally confirmed in bimetallic Ni–Fe based catalysts with respect to CO$_{2}$ activation during the methanation reaction and may also be at the origin of better performance of other CO$_{2}$-hydrogenation catalysts. The insight into the structural surface changes reported in this study show the dynamics of the Fe–Ni system and allow the development of realistic surface models as basis for CO$_{2}$ activation and possible intermediates in these bimetallic systems

Purely infinite simple C*-algebras that are principal groupoid C*-algebras

From a suitable groupoid G, we show how to construct an amenable principal groupoid whose C*-algebra is a Kirchberg algebra which is KK-equivalent to C*(G). Using this construction, we show by example that many UCT Kirchberg algebras can be realised as the C*-algebras of amenable principal groupoids.Comment: 20 pages, 1 picture prepared using Tik

Basement membrane ligands initiate distinct signalling networks to direct cell shape

Cells have evolved mechanisms to sense the composition of their adhesive microenvironment. Although much is known about general mechanisms employed by adhesion receptors to relay signals between the extracellular environment and the cytoskeleton, the nuances of ligand-specific signalling remain undefined. Here, we investigated how glomerular podocytes, and four other basement membrane-associated cell types, respond morphologically to different basement membrane ligands. We defined the composition of the respective adhesion complexes using mass spectrometry-based proteomics. On type IV collagen, all epithelial cell types adopted a round morphology, with a single lamellipodium and large adhesion complexes rich in actin-binding proteins. On laminin (511 or 521), all cell types attached to a similar degree but were polygonal in shape with small adhesion complexes enriched in endocytic and microtubule-binding proteins. Consistent with their distinctive morphologies, cells on type IV collagen exhibited high Rac1 activity, while those on laminin had elevated PKCα. Perturbation of PKCα was able to interchange morphology consistent with a key role for this pathway in matrix ligand-specific signalling. Therefore, this study defines the switchable basement membrane adhesome and highlights two key signalling pathways within the systems that determine distinct cell morphologies. Proteomic data are availableviaProteomeXchange with identifier PXD017913