We consider a one-parameter family of composite fields — bi-linear in the components of the stress-energy tensor — which generalise the $$ \mathrm{T}\overline{\mathrm{T}} $$ T T ¯ operator to arbitrary space-time dimension d ≥ 2. We show that they induce a deformation of the classical action which is equivalent — at the level of the dynamics — to a field-dependent modification of the background metric tensor according to a specific flow equation. Even though the starting point is the flat space, the deformed metric is generally curved for any d > 2, thus implying that the corresponding deformation can not be interpreted as a coordinate transformation. The central part of the paper is devoted to the development of a recursive algorithm to compute the coefficients of the power series expansion of the solution to the metric flow equation. We show that, under some quite restrictive assumptions on the stress-energy tensor, the power series yields an exact solution. Finally, we consider a class of theories in d = 4 whose stress-energy tensor fulfils the assumptions above mentioned, namely the family of abelian gauge theories in d = 4. For such theories, we obtain the exact expression of the deformed metric and the vierbein. In particular, the latter result implies that ModMax theory in a specific curved space is dynamically equivalent to its Born-Infeld-like extension in flat space. We also discuss a dimensional reduction of the latter theories from d = 4 to d = 2 in which an interesting marginal deformation of d = 2 field theories emerges.

This study investigates the feasibility and consequences of using complex, nonlinear geometries in the manufacturing of soft robots actuated with shape memory alloys (SMAs). Anatomically-informed shaping of the functional elements was exploited to design the components of a finger-like soft robot. The SMAs were characterised and selected to provide the device actuation. This process involved thermo-mechanical tests to obtain material parameters for a finite element method model, which was then used to carry out a comparative analysis of different actuator shapes. Additive manufacturing and multi-material integration were then exploited to manufacture the device. The soft robot actuation was characterised using a combined thermal and motion-capture-based analysis. The paper presents a shape-mediated design strategy to obtain soft actuation in an integrated multi-material through the introduction of conjugated nonlinear shapes for the constituents and a spatially-changing relationship between their sections/stiffnesses.

Objective. The evolution of new prosthetic and osteosynthesis devices has led to better outcomes and therefore more frequent surgical indications. As a consequence, an increased incidence of complications such as infections or aseptic loosening in orthopedic and trauma surgery are being recorded in general population. MicroDTTect is a quick and simple system that is useful to detect low grade or bio-film related infections. The aim of this study was to evaluate the reliability of MicroDTTect in detection of orthopedic infections compared to conventional culture of tissue samples. Methods. The population enrolled was composed of 13 patients undergoing surgery for prosthesis or osteosynthetic device failure or loosening. The MicroDTTect system and traditional culture of tissue samples were applied to identify the pathogens and compared with each other. Results. MicroDTTect had a higher sensitivity compared to conventional culture of tissue samples. Two cases resulted positive while the traditional culture sample showed a false negative result. In addition, with MicroDTTect a polymicrobial infection was identified, while with traditional methods was misdiagnosed. Conclusions. We showed that treatment of suspected implant infections using the MicroD-TTect device improves microbiological diagnosis with more sensitive results, leading to a more accurate treatment.

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