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1. The mathematics of thin structures

   https://doi.org/10.1090/qam/1628  

   Babadjian, Jean-François; Di Fratta, Giovanni; Fonseca, Irene; Francfort, Gilles; Lewicka, Marta; Muratov, Cyrill (March 2023, Quarterly of Applied Mathematics)

   This article offers various mathematical contributions to the behavior of thin films. The common thread is to view thin film behavior as the variational limit of a three-dimensional domain with a related behavior when the thickness of that domain vanishes. After a short review in Section 1 of the various regimes that can arise when such an asymptotic process is performed in the classical elastic case, giving rise to various well-known models in plate theory (membrane, bending, Von Karmann, etc…), the other sections address various extensions of those initial results. Section 2 adds brittleness and delamination and investigates the brittle membrane regime. Sections 4 and 5 focus on micromagnetics, rather than elasticity, this once again in the membrane regime and discuss magnetic skyrmions and domain walls, respectively. Finally, Section 3 revisits the classical setting in a non-Euclidean setting induced by the presence of a pre-strain in the model. 

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2. Mechanically Programming the Cross-Sectional Shape of Soft Growing Robotic Structures for Patient Transfer

   Osele, G; Barhydt, K; Sullivan, T; Asada, H; Okamura, A (October 2025, IEEE)

   Pneumatic soft everting robotic structures have the potential to facilitate human transfer tasks due to their ability to grow underneath humans without sliding friction and their utility as a flexible sling when deflated. Tubular structures naturally yield circular cross-sections when inflated, whereas a robotic sling must be both thin enough to grow between a human and their resting surface and wide enough to cradle the human. Recent works have achieved flattened cross-sections by including rigid components into the structure, but this reduces conformability to the human. We present a method of mechanically programming the cross-section of soft everting robotic structures using flexible strips that constrain radial expansion between points along the outer membrane. Our method enables simultaneously wide and thin inflated profiles, and maintains the full multi-axis flexibility of traditional slings when deflated. We develop and validate a model relating geometric design specifications to fabrication parameters, and experimentally characterize their effects on growth rate. Finally, we prototype a soft growing robotic sling system and demonstrate its use for assisting a single caregiver in bed-to-chair patient transfer. 

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3. Building a universal orientation system for thin sections

   https://doi.org/doi.org/10.1016/j.jsg.2018.09.019  

   Tikoff, Basil; Chatzaras, Vasileios; Newman, Julie; Roberts, Nicolas (January 2019, Journal of structural geology)

   We present an orientation system for thin sections used for microanalysis, applicable to both billets and cores. The orientation system enables spatially referenced observations and consists of three parts. First, we establish a reference corner that is the uppermost corner of the sample on the thin section, in its original geographic orientation in the field or laboratory setting. This corner is tied to a right-hand coordinate system, in which all reference axes point downward. A geographic direction-based, rather than uppermost corner-based, convention for a reference corner can be substituted for projects that utilize sub-horizontally oriented thin sections. The reference corner - combined with orientation metadata - define a unique position of the thin section in geographic space. Second, we propose a system of small saw cuts (notches) that minimizes the number of notches required on the sample, to distinguish both the reference corner and the orientation of the thin section relative to fabric (e.g., foliation/lineation), if present. The utility of a notching standard is that it provides an inherent doublecheck on thin section orientation and facilitates sharing between users. Third, we develop a grid system in order to locate features of interest on the thin section, relative to the reference corner. Any of these systems – referencing, notching, and gridding – can be used independently. These systems are specifically designed to work with digital data systems, which are currently being developed, allowing researchers to share microstructural data with each other and facilitating new types of big data science in the field of structural geology. 

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4. Depositional history of Devonian and Mississippian rocks from southern Mongolia: Stratigraphic and sedimentologic framework of a volcanic arc system

   https://doi.org/10.1007/s12549-025-00649-2  

   Königshof, Peter; Carmichael, Sarah K; Waters, Johnny A; Munkhjargal, Ariuntogos; Gonchigdorj, Sersmaa (September 2025, Palaeobiodiversity and Palaeoenvironments)

   Abstract This report provides a detailed description of Devonian and Carboniferous formations in the Shinejinst area, southern Mongolia and places them into a regional context. Based on more than 120 thin sections, polished slabs, and field observations a detailed sedimentological/facies study provides information on the depositional development of an island arc system. This study forms a more detailed survey of the same section as our recent overview publication, which contained an updated conodont biostratigraphy of the Shinejinst area. The Shinejinst region is compared with rocks of the coeval Bayankhoshuu Ruins section further in the east. Both sections exhibit differences in the rock record, which can be explained by facies differences due to different settings, but both sections show similarities and interactions, which are mainly driven by regional tectonics and eustatic sea-level changes. Whereas the eastern section (Bayankhoshuu Ruins section) records more deep-water environments, the western section (Shinejinst section) is characterised mainly by shallow-water carbonate ramp successions. In the eastern section subduction started in the Early Devonian and volcanic activity had its most productive phase during the Givetian and lasted in both sections into the Mississippian, when final amalgamation of the arc system with an unknown arc or microcontinent took place. Both sections likely belong to the same island arc terrane, the Mandalovoo Terrane. This area is characterised by very complex geology, and these results will provide a useful framework for any future geologic mapping of the region. This publication is a contribution to the Special Series on “The Central Asian Orogenic Belt (CAOB) during Late Devonian: New insights from southern Mongolia” published in this journal. 

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5. Dissipative dark matter on FIRE – I. Structural and kinematic properties of dwarf galaxies

   https://doi.org/10.1093/mnras/stab2042  

   Shen, Xuejian; Hopkins, Philip F; Necib, Lina; Jiang, Fangzhou; Boylan-Kolchin, Michael; Wetzel, Andrew (August 2021, Monthly Notices of the Royal Astronomical Society)

   null (Ed.)

   ABSTRACT We present the first set of cosmological baryonic zoom-in simulations of galaxies including dissipative self-interacting dark matter (dSIDM). These simulations utilize the Feedback In Realistic Environments galaxy formation physics, but allow the dark matter to have dissipative self-interactions analogous to standard model forces, parametrized by the self-interaction cross-section per unit mass, (σ/m), and the dimensionless degree of dissipation, 0 < fdiss < 1. We survey this parameter space, including constant and velocity-dependent cross-sections, and focus on structural and kinematic properties of dwarf galaxies with $$M_{\rm halo} \sim 10^{10-11}{\, \rm M_\odot }$$ and $$M_{\ast } \sim 10^{5-8}{\, \rm M_\odot }$$. Central density profiles (parametrized as ρ ∝ rα) of simulated dwarfs become cuspy when $$(\sigma /m)_{\rm eff} \gtrsim 0.1\, {\rm cm^{2}\, g^{-1}}$$ (and fdiss = 0.5 as fiducial). The power-law slopes asymptote to α ≈ −1.5 in low-mass dwarfs independent of cross-section, which arises from a dark matter ‘cooling flow’. Through comparisons with dark matter only simulations, we find the profile in this regime is insensitive to the inclusion of baryons. However, when $$(\sigma /m)_{\rm eff} \ll 0.1\, {\rm cm^{2}\, g^{-1}}$$, baryonic effects can produce cored density profiles comparable to non-dissipative cold dark matter (CDM) runs but at smaller radii. Simulated galaxies with $$(\sigma /m) \gtrsim 10\, {\rm cm^{2}\, g^{-1}}$$ and the fiducial fdiss develop significant coherent rotation of dark matter, accompanied by halo deformation, but this is unlike the well-defined thin ‘dark discs’ often attributed to baryon-like dSIDM. The density profiles in this high cross-section model exhibit lower normalizations given the onset of halo deformation. For our surveyed dSIDM parameters, halo masses and galaxy stellar masses do not show appreciable difference from CDM, but dark matter kinematics and halo concentrations/shapes can differ. 

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