A moving boundary problem motivated by electric breakdown: I. Spectrum of linear perturbations

An interfacial approximation of the streamer stage in the evolution of sparks and lightning can be written as a Laplacian growth model regularized by a `kinetic undercooling' boundary condition. We study the linear stability of uniformly translating circles that solve the problem in two dimensions. In a space of smooth perturbations of the circular shape, the stability operator is found to have a pure point spectrum. Except for the zero eigenvalue for infinitesimal translations, all eigenvalues are shown to have negative real part. Therefore perturbations decay exponentially in time. We calculate the spectrum through a combination of asymptotic and series evaluation. In the limit of vanishing regularization parameter, all eigenvalues are found to approach zero in a singular fashion, and this asymptotic behavior is worked out in detail. A consideration of the eigenfunctions indicates that a strong intermediate growth may occur for generic initial perturbations. Both the linear and the nonlinear initial value problem are considered in a second paper.Comment: 37 pages, 6 figures, revised for Physica

A moving boundary model motivated by electric breakdown: II. Initial value problem

An interfacial approximation of the streamer stage in the evolution of sparks and lightning can be formulated as a Laplacian growth model regularized by a 'kinetic undercooling' boundary condition. Using this model we study both the linearized and the full nonlinear evolution of small perturbations of a uniformly translating circle. Within the linear approximation analytical and numerical results show that perturbations are advected to the back of the circle, where they decay. An initially analytic interface stays analytic for all finite times, but singularities from outside the physical region approach the interface for $t\to\infty$, which results in some anomalous relaxation at the back of the circle. For the nonlinear evolution numerical results indicate that the circle is the asymptotic attractor for small perturbations, but larger perturbations may lead to branching. We also present results for more general initial shapes, which demonstrate that regularization by kinetic undercooling cannot guarantee smooth interfaces globally in time.Comment: 44 pages, 18 figures, paper submitted to Physica

Cystic artery pseudo-aneurysm: a complication of xanthogranulomatous cholecystitis

A 54-year-old man presented for radiology with pain and a feeling of fullness in the upper abdomen and an epigastric mass. Ultrasound revealed a large cystic mass with internal echoes, lying posterior and inferior to left lobe of the liver. The gallbladder was thick-walled and contracted, and contained a calculus and echogenic sludge. A cystic structure that produced swirling flow signals on colour Doppler was demonstrated within the gallbladder. The CT scan showed a thickened gallbladder with adjacent inflammation and a 2-cm pseudo-aneurysm in its wall. High-density material was present in the gallbladder lumen, in the extra-hepatic bile ducts and around the gastrohepatic ligament. A thick haemorrhagic pus, from which Escherichia coli was cultured, was drained from the gastrohepatic collection. An elective coeliac angiogram demonstrated a solitary pseudo-aneurysm of the medial branch of the cystic artery. Selective catheterisation of this artery with a micro-catheter enabled complete exclusion of the pseudo-aneurysm by a single micro-coil. Histological examination of the gallbladder, which was ultimately removed at open cholecystectomy, demonstrated xanthogranulomatous cholecystitis

Building a circular supply chain. Achieving resilient operations with the circular economy

This is the final version. Available from the Ellen MacArthur Foundation via the link in this recordNote that Umair Tanveer (a contributing author) is listed individually in this record as he is at the University of ExeterThis paper highlights the fundamental contribution that supply chain professionals can make to the transition to a circular economy. It aims to provide a general understanding of how the circular economy and supply chain management fields are related to one another. By exploring the concept of a circular supply chain, the paper illustrates the role of supply chain professionals in operationalising circular economy initiatives within their organisations, as well as the opportunities and challenges they may encounter along the way. The paper also provides initial recommendations for and examples of companies overcoming some of these challenges, based on the experiences of supply chain professionals involved in the research. Additional research into the real-life experiences of such professionals will be needed to gain a fuller understanding of the exact changes needed to their role, and the best practices they can deploy to effectively transition to circular supply chains. This paper has been developed in collaboration with the Circular Supply Chain Network, a global community of supply chain professionals committed to accelerating the transition to circular supply chains. The content has been informed by a set of interviews conducted in the Spring of 2023, as well as insights gathered from a working group series run with supply chain professionals from the Foundation’s Network in June of 202

Distal radius fractures: a prospective study of the clinical and radiological outcomes in surgically managed patients

Background: Objective of the research was to evaluate radiological and functional outcome in fractures of the distal radius treated by various surgical methods.Methods: 89 patients with distal radius fractures were randomly divided into three groups according to a computer-generated table of randomization. 40 patients were managed by K wire fixation. 22 patients were managed by external fixator. 27 patients were managed by volar plating technique. Anatomical restoration was evaluated by posterior-anterior and lateral radiographs obtained preoperatively and at 09 months of follow up to evaluate radial height (RH), radial inclination (RI) and volar tilt (VT). Functional outcome was evaluated using Mayo scoring system.Results: According to Mayo score, in K-wire group 72.5% (n=29) patients had excellent to good outcome, 17.5% (n=7) had fair outcome while as 10% (n=4) patients had poor outcome. In external fixator group 72.7% (n=16) patients had excellent to good outcome while as 27.3% (n=6) had fair outcome. In volar plating group 81.5% (n=22) patients had excellent to good outcome while as 18.5% (n=5) had fair outcome.Conclusions: In our study we found that volar locked plating provides advantage in dorsally or volarly displaced intra-articular fractures with excellent to good radiological outcome. However, in type B (partial intra-articular fractures) fractures, volar locking compression plate (LCP) and external fixator provide almost equivocal results. Percutaneous pinning can be recommended for extra-articular or simple intra-articular fracture patterns, with a loss of volar and/or RI but without significant radial shortening

An Insight into the Application of Gradations of Circularity in the Food Packaging Industry: A Systematic Literature Review and a Multiple Case Study

This is the final version. Available on open access from MDPI via the DOI in this recordData Availability Statement: The data presented in this study are available on request from the corresponding author. The data are not publicly available due to primary data collection and to protect the identities of the participants (interviews were conducted and transcribed).Given its unsustainable growth, the food packaging industry (FPI) has become a priority industry in the circular economy. Given the academic significance attributed to the gradations of circularity in maximising resource efficiency in the food packaging industry, this paper aims to identify the current state of the application of those gradations of circularity in the FPI by finding the least and most commonly used circular strategies in the FPI. Moreover, it aims to identify the drivers of and barriers to the implementation of the gradations of circularity and the levers for overcoming such barriers through SLR using multiple case studies, namely five small-medium enterprises (SMEs) in the FPI that each represent one of the five least implemented circular strategies. The research identified that the efforts of the FPI toward adopting circular strategies were not aligned with the gradations of circularity. Based on the research findings, a lever–barrier matrix is proposed as a toolkit for SMEs planning a transition toward the circular economy or are in the transition phase

Bilateral total duplication of clavicle: First reported case

A very rare first case of bilateral duplication of the clavicle is presented here. Duplication of the clavicle has been described in only six reports based on a search of the world literature, with single case of bilateral duplication (incomplete) of clavicle being reported. The detection of anatomic anomalies are increasing with the advancement of technology in medicine field. This case is more of academic interest as it is the first case of total bilateral duplication of clavicle

Extending the scope of microscopic solvability: Combination of the Kruskal-Segur method with Zauderer decomposition

Successful applications of the Kruskal-Segur approach to interfacial pattern formation have remained limited due to the necessity of an integral formulation of the problem. This excludes nonlinear bulk equations, rendering convection intractable. Combining the method with Zauderer's asymptotic decomposition scheme, we are able to strongly extend its scope of applicability and solve selection problems based on free boundary formulations in terms of partial differential equations alone. To demonstrate the technique, we give the first analytic solution of the problem of velocity selection for dendritic growth in a forced potential flow.Comment: Submitted to Europhys. Letters, No figures, 5 page

What configurations of structures facilitate supply chain learning? A supply chain network and complexity perspective

This is the author accepted manuscript. The final version is available from Emerald via the DOI in this recordPurpose This study explores how factors arising from supply chain (SC) network and complexity work together in supply chain learning (SCL) behavior. Design/methodology/approach Fuzzy set qualitative comparative analysis, which is an emerging configurational analysis method, was adopted to examine the complex combination of five influencing factors. The data were collected using a two-stage survey. First, the authors selected seven typical firms with an awareness of SCL. Second, questionnaires were sent to the partners of the seven selected firms, and 156 valid questionnaires were obtained from 76 firms. Findings Drawing on emergent insights from the initiative, the authors find that multiple configurations of SC network and complexity lead to high SCL. Specifically, weak ties are necessary conditions of such learning, while strong ties are also conducive to this. Moreover, a moderate SC complexity is conducive to SCL. Practical implications This study enriches the understanding of SCL and provides new insights for SC management practitioners to take measures to improve it. Originality/value This study addresses the lack of in-depth understanding of the antecedent conditions of SCL in the literature. It establishes an integrated and comprehensive theoretical framework of such learning based on contingency theory. Additionally, this study incorporates ambidextrous SCL (i.e. creation capability and dispersion capacity). An overall prototype of SCL capability is proposed on SC network and complexity theory.Humanities and Social Science Funding of the Ministry of Education of ChinaChina Postdoctoral Science Foundatio

Transformative capabilities of MedTech organizations in driving circularity in the healthcare industry: Insights from multiple cases

This is the author accepted manuscript. The final version is available on open access from Elsevier via the DOI in this recordData availability: Data will be made available on request.The healthcare industry's significant environmental impact has prompted the urgent need for sustainable practices. MedTech companies play a crucial role in advancing circularity within the sector by adopting sustainable approaches to product design, resource management, and waste reduction. This research aims to explore how MedTech companies initiate and drive transformation towards circular practices and the key factors influencing their successful transition. Using a qualitative approach, four multinational MedTech companies' case studies are conducted, employing semi-structured interviews with 33 managers and healthcare professionals. The results reveal a model grounded in dynamic capabilities, comprising three stages: sensing, seizing, and transforming, guided by adaptability and flexibility. The study extends the understanding of how MedTech companies can proactively respond to environmental challenges and embrace circular economy practices. Furthermore, the model offers practical implications for MedTech companies to foster sustainable practices, optimize resources, and enhance circularity in the healthcare industry