54 research outputs found
Confirmation of Lagrange Hypothesis for Twisted Elastic Rod
The history of structural optimization as an exact science begins possibly
with the celebrated Lagrange problem: to find a curve which by its revolution
about an axis in its plane determines the rod of greatest efficiency. The
Lagrange hypothesis, that the optimal rod possesses the constant cross-section
was abandoned for Euler buckling problem. In this Article the Lagrange
hypothesis is proved to be valid for Greenhill's problem of torque buckling.
The corresponding isoperimetric inequality is affirmed.Comment: 4 page
Contour models of cellular adhesion
The development of traction-force microscopy, in the past two decades, has
created the unprecedented opportunity of performing direct mechanical
measurements on living cells as they adhere or crawl on uniform or
micro-patterned substrates. Simultaneously, this has created the demand for a
theoretical framework able to decipher the experimental observations, shed
light on the complex biomechanical processes that govern the interaction
between the cell and the extracellular matrix and offer testable predictions.
Contour models of cellular adhesion, represent one of the simplest and yet most
insightful approach in this problem. Rooted in the paradigm of active matter,
these models allow to explicitly determine the shape of the cell edge and
calculate the traction forces experienced by the substrate, starting from the
internal and peripheral contractile stresses as well as the passive restoring
forces and bending moments arising within the actin cortex and the plasma
membrane. In this chapter I provide a general overview of contour models of
cellular adhesion and review the specific cases of cells equipped with
isotropic and anisotropic actin cytoskeleton as well as the role of bending
elasticity.Comment: 24 pages, 9 figures. arXiv admin note: text overlap with
arXiv:1304.107
The dynamic stability and nonlinear resonance of a flexible connecting rod: Continuous parameter model
The transverse vibrations of a flexible connecting rod in an otherwise rigid slider-crank mechanism are considered. An analytical approach using the method of multiple scales is adopted and particular emphasis is placed on nonlinear effects which arise from finite deformations. Several nonlinear resonances and instabilities are investigated, and the influences of important system parameters on these resonances are examined in detail.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43330/1/11071_2004_Article_BF00162233.pd
Dividend Stickiness in Japan
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The paper describes the introduction of an emphasis on ‘personal security’ in human security thinking and practice, as part of the ultimately unsuccessful attempt to compartmentalize the pursuit of security. It reviews the past twenty years of attention to ‘personal security’: both in compartments that consider organized physical violence or threats to personal safety and property (‘citizen security’), and as parts of more wide-ranging examination of threats to fulfilment of basic needs and rights, for example in comprehensive mapping exercises undertaken in various UNDP Regional and National Human Development Reports or in studies of women’s security. The paper reflects on the complex process of opening-up conventional security thinking and practice, seeking value-added and depth without shrinking into preconceived compartments
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