Periodic Patterns and Energy States of Buckled Films on Compliant Substrates

Thin stiff films on compliant elastic substrates subject to equi-biaxial compressive stress states are observed to buckle into various periodic mode patterns including checkerboard, hexagonal and herringbone. An experimental setting in which these modes are observed and evolve is described. The modes are characterized and ranked by the extent to which they reduce the elastic energy of the film–substrate system relative to that of the unbuckled state over a wide range of overstress. A new mode is identified and analyzed having nodal lines coincident with an equilateral triangular pattern. Two methods are employed to ascertain the energy in the buckled state: an analytical upper-bound method and a full numerical analysis. The upper-bound is shown to be reasonably accurate to large levels of overstress. For flat films, except at small states of overstress where the checkerboard is preferred, the herringbone mode has the lowest energy, followed by the checkerboard, with the hexagonal, triangular, and one-dimensional modes lowering the energy the least. At low overstress, the hexagonal mode is observed in the experiments not the square mode. It is proposed that a slight initial curvature of the film may play role in selecting the hexagonal pattern accompanied by a detailed analysis. An intriguing finding is that the hexagonal and triangular modes have the same energy in the buckled state and, moreover, a continuous transition between these modes exists involving a linear combination of the two modes with no change in energy. Experimental observations of various periodic modes are discussed with reference to the energy landscape. Discrepancies between observations and theory are identified and open issues are highlighted.Engineering and Applied Science

Optimising the impact of health services research on the organisation and delivery of health services : a mixed-methods study

The research reported in this issue of the journal was funded by the HSDR programme or one of its preceding programmes as project number 16/52/21.Background The limitations of ‘knowledge transfer’ are increasingly recognised, with growing interest in ‘knowledge co-production in context’. One way of achieving the latter is by ‘embedding’ researchers in health service settings, yet how to deliver such schemes successfully is poorly understood. Objectives The objectives were to examine the nature of ‘embedded knowledge co-production’ and explore how embedded research initiatives can be designed more effectively. Design The study used four linked workstreams. Workstream 1 involved two parallel literature reviews to examine how ‘knowledge co-production’ and ‘embedded research’ are conceptualised, operationalised and discussed. In workstream 2, a scoping review of exisiting or recent ‘embedded researcher’ schemes in UK health settings was carried out. Workstream 3 involved developing four in-depth case studies on such schemes to understand their mechanisms, effectiveness and challenges. In workstream 4, insights from the other workstreams were used to provide recommendations, guidance and templates for the different ways embedded co-production may be framed and specified. The overall goal was to help those interested in developing and using such approaches to understand and address the design choices they face. Setting Embedded research initiatives in UK health settings. Data sources Data were sourced from the following: analysis of the published and grey literature (87 source articles on knowledge co-production, and 47 published reports on extant embedded research initiatives), documentation and interviews with key actors across 45 established embedded research initiatives, in-depth interviews and site observations with 31 participants over 12 months in four intensive case studies, and informal and creative engagement in workshops (n = 2) and with participants in embedded research initiatives who joined various managed discussion forums. Participants The participants were stakeholders and participants in embedded research initiatives. Results The literature reviews from workstream 1 produced practical frameworks for understanding knowledge co-production and embedded research initiatives, which, with the scoping review (workstream 2), informed the identification and articulation of 10 design concerns under three overarching categories: intent (covering outcomes and power dynamics), structures (scale, involvement, proximity and belonging) and processes (the functional activities, skills and expertise required, nature of the relational roles, and the learning mechanisms employed). Current instances of embedded research were diverse across many of these domains. The four case studies (workstream 3) added insights into scheme dynamics and life cycles, deepening understanding of the overarching categories and showing the contingencies experienced in co-producing knowledge. A key finding is that there was often a greater emphasis on embeddedness per se than on co-production, which can be hard to discern. Finally, the engaging and influencing activities running throughout (workstream 4) allowed these research-rooted insights to be translated into practical tools and resources, evidenced by peer-reviewed publications, for those interested in exploring and developing the approach. Conclusions Embedded research has a strong underpinning rationale, and more is becoming known about its design and management challenges. The tools and resources developed in this project provide a coherent evidence-informed framework for designing, operationalising and managing such schemes. It cannot yet be said with clarity that the potential benefits of embedded research are always deliverable, nor what the cost would be. Future work With the means to describe and categorise different types of embedded research initiatives, more evaluative work is now needed to examine the relative merits and costs of different designs. Funding This project was funded by the National Institute for Health Research (NIHR) Health and Social Care Delivery Research programme and will be published in full in Health and Social Care Delivery Research; Vol. 10, No. 3. See the NIHR Journals Library website for further project information.Publisher PDFPeer reviewe

Optical Lattices: Theory

This chapter presents an overview of the properties of a Bose-Einstein condensate (BEC) trapped in a periodic potential. This system has attracted a wide interest in the last years, and a few excellent reviews of the field have already appeared in the literature (see, for instance, [1-3] and references therein). For this reason, and because of the huge amount of published results, we do not pretend here to be comprehensive, but we will be content to provide a flavor of the richness of this subject, together with some useful references. On the other hand, there are good reasons for our effort. Probably, the most significant is that BEC in periodic potentials is a truly interdisciplinary problem, with obvious connections with electrons in crystal lattices, polarons and photons in optical fibers. Moreover, the BEC experimentalists have reached such a high level of accuracy to create in the lab, so to speak, paradigmatic Hamiltonians, which were first introduced as idealized theoretical models to study, among others, dynamical instabilities or quantum phase transitions.Comment: Chapter 13 in Part VIII: "Optical Lattices" of "Emergent Nonlinear Phenomena in Bose-Einstein Condensates: Theory and Experiment," edited by P. G. Kevrekidis, D. J. Frantzeskakis, and R. Carretero-Gonzalez (Springer Series on Atomic, Optical, and Plasma Physics, 2007) - pages 247-26

Clinical grade ACE2 as a universal agent to block SARS-CoV-2 variants

The recent emergence of multiple SARS-CoV-2 variants has caused considerable concern due to both reduced vaccine efficacy and escape from neutralizing antibody therapeutics. It is, therefore, paramount to develop therapeutic strategies that inhibit all known and future SARS-CoV-2 variants. Here, we report that all SARS-CoV-2 variants analyzed, including variants of concern (VOC) Alpha, Beta, Gamma, Delta, and Omicron, exhibit enhanced binding affinity to clinical grade and phase 2 tested recombinant human soluble ACE2 (APN01). Importantly, soluble ACE2 neutralized infection of VeroE6 cells and human lung epithelial cells by all current VOC strains with markedly enhanced potency when compared to reference SARS-CoV-2 isolates. Effective inhibition of infections with SARS-CoV-2 variants was validated and confirmed in two independent laboratories. These data show that SARS-CoV-2 variants that have emerged around the world, including current VOC and several variants of interest, can be inhibited by soluble ACE2, providing proof of principle of a pan-SARS-CoV-2 therapeutic

Manipulation of matter waves using Bloch and Bloch-Zener oscillations

We present theoretical and numerical results on the dynamics of ultracold atoms in an accelerated single- and double-periodic optical lattice. In the single-periodic potential Bloch oscillations can be used to generate fast directed transport with very little dispersion. The dynamics in the double-periodic system is dominated by Bloch-Zener oscillations, i.e. the interplay of Bloch oscillations and Zener tunneling between the subbands. Apart from directed transport, the latter system permits various interesting applications, such as widely tunable matter wave beam splitters and Mach-Zehnder interferometry. As an application, a method for efficient probing of small nonlinear mean-field interactions is suggested. PACS numbers: 03.65.-w, 03.75.Be, 03.75.Dg, 03.75.LmManipulation of matter waves using Bloch and Bloch-Zener oscillations 2 1