While most animal-bacterial symbioses are reestablished each successive generation, the mechanisms by which the host and its potential microbial partners ensure tissue colonization remain largely undescribed. We used the model association between the squid Euprymna scolopes and Vibrio fischeri to examine this process. This light organ symbiosis is initiated when V. fischeri cells present in the...

We present a microscopic model of a disordered viscoelastic active solid, i.e., an active material whose long time behavior is elastic as opposed to viscous. It is composed of filaments, passive cross-links, and molecular motors powered by stored chemical energy, e.g., actomyosin powered by adenosine triphosphate. Our model allows us to study the collective behavior of contractile active elemen...

To model nonlinear viscous dissipative motions in solids, acoustical physicists usually add terms linear in Ė, the material time derivative of the Lagrangian strain tensor E, to the elastic stress tensor σ derived from the expansion to the third (sometimes fourth) order of the strain energy density E=E(tr E,tr E(2),tr E(3)). Here it is shown that this practice, which has been widely used in the...

Multiparticle sintering is encountered in almost all high temperature processes for material synthesis (titania, silica, and nickel) and energy generation (e.g., fly ash formation) resulting in aggregates of primary particles (hard- or sinter-bonded agglomerates). This mechanism of particle growth is investigated quantitatively by mass and energy balances during viscous sintering of amorphous a...

Asphalt is a visco-elastic material having properties of elastic solid at low temperature and viscous liquid at high temperature. Properties of asphalt binder depend upon temperature, rate of loading and aging conditions. Although asphalt binder is only 4-5 % of asphalt concrete mix by weight but it plays a vital role in defining the pavement performance. That is, pavement response is heavily d...

Introduction Conclusions References Tables Figures ◭ ◮ ◭ ◮ Back Close Full Screen / Esc Abstract Introduction Conclusions References Tables Figures ◭ ◮ ◭ ◮ Back Close Full Screen / Esc Abstract Homogeneous nucleation of ice within aqueous solution droplets and their subsequent crystallisation is thought to play a significant role in upper tropospheric ice cloud formation. It is normally assumed...

Submitted for the DFD08 Meeting of The American Physical Society Deformation of Elastic Particles in Viscous Shear Flow TONG GAO, HOWARD HU, University of Pennsylvania — The dynamics of two dimensional elastic particles in a Newtonian viscous shear flow is studied numerically. A constitutive equation is constructed for an incompressible “Neo-Hookean” elastic solid where the extra stress tensor ...

The mechanical response of Polyethylene Terephthalate (PET) in elongation is strongly dependent on temperature, strain and strain rate. Near the glass transition temperature Tg, the stress vs strain curves present a strain hardening effect vs strain under conditions of large deformations. At a given strain value, the strain rate has also an increasing influence on the stress value. The main goa...

We develop a viscous model of plate bending suitable for studying ice-sheet flexure due to subglacial lake filling and draining, and apply this model to determine the area of ice-sheet uplift surrounding a subglacial lake. The choice of a viscous model reflects our interest in Antarctic subglacial lakes, which can fill and drain on time scales of months to decades. Experiments with idealized la...

Osmotic, electrostatic, and/or hydrational swellings are essential mechanisms in the deformation behavior of porous media, such as biological tissues, synthetic hydrogels, and clay-rich rocks. Present theories are restricted to incompressible constituents. This assumption typically fails for bone, in which electrokinetic effects are closely coupled to deformation. An electrochemomechanical form...