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#mechanics

4 posts2 participants0 posts today
Public
Rxiv mechanobio

📰 "Equilibrium Conserving Neural Operators for Super-Resolution Learning"
arxiv.org/abs/2504.13422 #Physics.Comp-Ph #Mechanics #Matrix #Cs.Lg

arXiv logo
arXiv.orgEquilibrium Conserving Neural Operators for Super-Resolution LearningNeural surrogate solvers can estimate solutions to partial differential equations in physical problems more efficiently than standard numerical methods, but require extensive high-resolution training data. In this paper, we break this limitation; we introduce a framework for super-resolution learning in solid mechanics problems. Our approach allows one to train a high-resolution neural network using only low-resolution data. Our Equilibrium Conserving Operator (ECO) architecture embeds known physics directly into the network to make up for missing high-resolution information during training. We evaluate this ECO-based super-resolution framework that strongly enforces conservation-laws in the predicted solutions on two working examples: embedded pores in a homogenized matrix and randomly textured polycrystalline materials. ECO eliminates the reliance on high-fidelity data and reduces the upfront cost of data collection by two orders of magnitude, offering a robust pathway for resource-efficient surrogate modeling in materials modeling. ECO is readily generalizable to other physics-based problems.
Public
Rxiv mechanobio

📰 "Structure and function of vimentin in the generation and secretion of extracellular vimentin in response to inflammation"
doi.org/doi:10.1186/s12964-025
pubmed.ncbi.nlm.nih.gov/402515
#Mechanics #Vimentin

BioMed CentralStructure and function of vimentin in the generation and secretion of extracellular vimentin in response to inflammation - Cell Communication and SignalingThe canonical functions of vimentin in cell mechanics and migration have been recently expanded by the discovery of new roles for extracellular vimentin (ECV) in immune responses to infection, injury and cancer. In contrast with the predominantly filamentous form of intracellular vimentin, ECV exists largely as soluble oligomers. The release of ECV from intact cells is dependent on mechanisms that regulate the assembly and disassembly of intracellular vimentin, which are influenced by discrete post-translational modifications. In this review we highlight the processes that promote the conversion of intracellular and insoluble vimentin filaments to ECV and secretion mechanisms. Insights into the regulation of ECV release from stromal and immune cells could provide new diagnostic and therapeutic approaches for assessing and controlling inflammatory diseases.
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Pustam | पुस्तम | পুস্তম🇳🇵

A cycloidal pendulum - one suspended from the cusp of an inverted cycloid - is isochronous, meaning its period is constant regardless of the amplitude of the swing. Please find the proof using energy methods: Lagrange's equations (in the images attached to the reply).

Background:
The standard pendulum period of 2πL/g or frequency g/L holds only for small oscillations. The frequency becomes smaller as the amplitude grows. If you want to build a pendulum whose frequency is independent of the amplitude, you should hang it from the cusp of a cycloid of a certain size, as shown in the gif. As the string wraps partially around the cycloid, the effect decreases the length of the string in the air, increasing the frequency back up to a constant value.

In more detail:
A cycloid is the path taken by a point on the rim of a rolling wheel. The upside-down cycloid in the gif can be parameterized by (x,y)=R(θ−sin⁡θ,−1+cos⁡θ), where θ=0 corresponds to the cusp. Consider a pendulum of length L=4R hanging from the cusp, and let α be the angle the string makes with the vertical, as shown (in the proof).

GIF
#Pendulum#Cycloid#Period
Public
CyanCqueak

My son pulled out a textbook at his tutoring centre and asked me to do this question.

Moving past the odd statement that the object is at rest when the forces aren't balanced, when I resolve the weight of the I get a net force along the slope of 2N, assuming a friction coefficient of 0.

The friction coefficient would need to be greater than 1 for the object to be at rest with the initial applied forces.

Textbook says the answer is 0. Am I missing something? #maths #mechanics

Public
Rxiv mechanobio

📰 "Spatial patterning of contractility by a mechanogen gradient underlies Drosophila gastrulation"
biorxiv.org/content/10.1101/20 #Mechanics #Cell

bioRxiv · Spatial patterning of contractility by a mechanogen gradient underlies Drosophila gastrulationDuring development cell deformations are spatially organized, however, how cellular mechanics is spatially controlled is unclear. Spatial control of cell identity often determines local cellular mechanics in a two-tiered mechanism. Theoretical studies also proposed that molecular gradients, so called 'mechanogens', spatially control mechanics. We report evidence of such a 'mechanogen' required for Drosophila gastrulation. We show that the GPCR ligand Fog, expressed in the posterior endoderm, diffuses and acts in a concentration-dependent manner to activate actomyosin contractility at a distance during a wave of tissue invagination. While Fog is uniformly distributed in the extracellular space, it forms a surface-bound gradient that activates Myosin-II via receptor oligomerization. This activity gradient self-renews as the wave propagates and is shaped by both receptor endocytosis and a feedback mechanism involving adhesion to the vitelline membrane by integrins. This exemplifies how chemical, mechanical and geometrical cues underly the emergence of a self-organized mechanogen activity gradient. ### Competing Interest Statement The authors have declared no competing interest.
Public
Rxiv mechanobio

📰 "Retinotopic Mechanics derived using classical physics"
arxiv.org/abs/2109.11632 #Physics.Bio-Ph #Mechanics #Q-Bio.Nc #Dynamics #Cell

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arXiv.orgRetinotopic Mechanics derived using classical physicsThe concept of a cell$'$s receptive field is a bedrock in systems neuroscience, and the classical static description of the receptive field has had enormous success in explaining the fundamental mechanisms underlying visual processing. Borne out by the spatio-temporal dynamics of visual sensitivity to probe stimuli in primates, I build on top of this static account with the introduction of a new computational field of research, retinotopic mechanics. At its core, retinotopic mechanics assumes that during active sensing receptive fields are not static but can shift beyond their classical extent. Specifically, the canonical computations and the neural architecture that supports these computations are inherently mediated by a neurobiologically inspired force field (e.g.,$R_s\propto \sim 1 /ΔM$). For example, when the retina is displaced because of a saccadic eye movement from one point in space to another, cells across retinotopic brain areas are tasked with discounting the retinal disruptions such active surveillance inherently introduces. This neural phenomenon is known as spatial constancy. Using retinotopic mechanics, I propose that to achieve spatial constancy or any active visually mediated task, retinotopic cells, namely their receptive fields, are constrained by eccentricity dependent elastic fields. I propose that elastic fields are self-generated by the visual system and allow receptive fields the ability to predictively shift beyond their classical extent to future post-saccadic location such that neural sensitivity which would otherwise support intermediate eccentric locations likely to contain retinal disruptions is transiently blunted.
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