Marino Arroyo's blog

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Paper on the mechanics of motility of a family of unicellular organisms called euglenids

Dear colleagues,

I wanted to draw your attention to a paper published last year in PNAS

where we analyze physical aspects of how euglenoids move

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PhD positions at the UPC-BarcelonaTech in Computational Mechanics/Numerical Analysis

Six PhD positions are available at the Laboratory of Computational Methods and Numerical Analysis ( of the Universitat Politècnica de Catalunya-BarcelonaTech ( in Spain.

The four-year PhD fellowships cover the full tuition, a monthly stipend, and health insurance.

Details about the different positions can be found at

The main research areas of the doctoral positions are:

- Reliable and robust model reduction for real-time simulations

- Phase field modeling and simulation of fracture in active materials and of biomembranes

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Assistant professor positions in Computational Mechanics in Barcelona

The Universitat Politècnica de Catalunya (UPC, ) opens tenure-track assistant professor positions in Computational Mechanics. Please follow this link for more information.

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Postdoc positions in Barcelona: modeling and simulation in biophysics

We have several postdoctoral positions open, funded by an European Research Council Starting Grant. We look for candidates with a PhD in Engineering, Physics, Chemistry, or
Applied/Computational Mathematics. In addition to excellent communication skills, initiative and an inclination for inter-disciplinary research, experience or interest in preferably more than two of the following areas is required:

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Multiwalled carbon nanotubes: the thicker, the softer

I. Arias and M. Arroyo, Size-Dependent Nonlinear Elastic Scaling of Multiwalled Carbon Nanotubes, Phys. Rev. Lett. 100, 085503 (2008).

Size matters for the mechanics of multiwalled carbon nanotubes (MWCNTs). It has been known for some time that MWCNTs often wrinkle under deformation exhibiting the so-called rippling deformation pattern, which makes MWCNTs much softer. Through large-scale multiscale simulations we have characterized with a power law the softer wrinkled response, and showed that the transition strain between the super-stiff behavior attributed to MWCNTs and this softer regime scales as the inverse of the tube diameter. Thus, the tera Pascal Young’s modulus can be fully exploited in devices and materials only for moderately sized tubes. Similarly, in interpreting experiments or designing devices, the classical Euler-Bernouilli beam theory can only be applied to such tubes. The elasticity of thicker tubes is nonlinear, typically display mixtures of wrinkled and unwrinkled sections, and often exhibit hysteretic mechanical behavior.

See for a related post.

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Two four-year doctoral fellowships at the LaCàN Research group (, Universitat Politècnica de Catalunya (UPC, Barcelona, Spain).

These two fellowships, funded by the Spanish Ministry of Science and Education ("beca FPI"), coverfull tuition, a monthly stipend and provide funds for short international research stays. The starting date is expected in the Summer-Fall 2008.

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Rippling and a phase-transforming mesoscopic model for multiwalled carbon nanotubes

Dear colleagues, 

I would like to share the following paper, in press in the Journal of the Mechanics and Physics of Solids. It can be found at the publisher's web at

 A preprint is also attached below.


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Maximum-Entropy approximants Matlab routines

Dear iMechanica colleagues,

I would like to announce that Matlab routines implementing the maximum-entropy approximation schemes presented in

Marino Arroyo and Michael Ortiz, “Local maximum-entropy approximation schemes: a seamless bridge between finite elements and meshfree methods”, International Journal for Numerical Methods in Engineering, 65:2167–2202 (2006).

can be downloaded from

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