Domino: exploring mobile collaborative software adaptation

Social Proximity Applications (SPAs) are a promising new area for ubicomp software that exploits the everyday changes in the proximity of mobile users. While a number of applications facilitate simple file sharing between co–present users, this paper explores opportunities for recommending and sharing software between users. We describe an architecture that allows the recommendation of new system components from systems with similar histories of use. Software components and usage histories are exchanged between mobile users who are in proximity with each other. We apply this architecture in a mobile strategy game in which players adapt and upgrade their game using components from other players, progressing through the game through sharing tools and history. More broadly, we discuss the general application of this technique as well as the security and privacy challenges to such an approach

Optimal Energy Dissipation in Sliding Friction Simulations

Non-equilibrium molecular dynamics simulations, of crucial importance in sliding friction, are hampered by arbitrariness and uncertainties in the removal of the frictionally generated Joule heat. Building upon general pre-existing formulation, we implement a fully microscopic dissipation approach which, based on a parameter-free, non-Markovian, stochastic dynamics, absorbs Joule heat equivalently to a semi-infinite solid and harmonic substrate. As a test case, we investigate the stick-slip friction of a slider over a two-dimensional Lennard-Jones solid, comparing our virtually exact frictional results with approximate ones from commonly adopted dissipation schemes. Remarkably, the exact results can be closely reproduced by a standard Langevin dissipation scheme, once its parameters are determined according to a general and self-standing variational procedure

Can one see the fundamental frequency of a drum?

We establish two-sided estimates for the fundamental frequency (the lowest eigenvalue) of the Laplacian in an open subset G of R^n with the Dirichlet boundary condition. This is done in terms of the interior capacitary radius of G which is defined as the maximal possible radius of a ball B which has a negligible intersection with the complement of G. Here negligibility of a subset F in B means that the Wiener capacity of F does not exceed gamma times the capacity of B, where gamma is an arbitrarily fixed constant between 0 and 1. We provide explicit values of constants in the two-sided estimates.Comment: 18 pages, some misprints correcte

Towards intelligent PID control

10.1016/0005-1098(92)90002-WAutomatica2811-9ATCA

Rapid assembly of PMMA microfluidic devices with PETE membranes for studying the endothelium

Biomicrofluidic devices and organ-on-a-chip (OOC) systems with integrated membranes are often fabricated from two different thermoplastic materials but bonding of such dissimilar thermoplastics remains challenging to manufacture at scale. Here, we present a method to bond poly(methylmethacrylate) layers to a polyethylene terephthalate porous membrane to create membrane-based microfluidic devices for biological barrier modeling. By combining milling, laser cutting and chlorocarbon-based solvent bonding supported by retention grooves, we achieved a fabrication rate of 36 devices in 5 h. Chlorocarbon-based solvent bonding resulted in bond strength of ~10 J/m2 and did not adversely affect the membrane pore structure or the channel cross-sectional shape. The bonded devices were found to support long term culture of human endothelial cells that developed expected morphology and cell-cell adhesion contacts as evidenced by immunofluorescent labeling of VE-cadherin. Barrier permeability was measured to be 3.38 × 106 cm/s for 10 kDa dextran using a sampling-based method compatible with mass spectrometry and scintillation techniques and was in agreement with literature. To validate the devices for cell migration experiments, THP-1 monocytes were introduced into devices with confluent endothelial monolayers. Monocytes adhered to and migrated through the endothelium. Activation of the endothelium with TNF-α prior to introducing monocytes significantly increased monocyte adhesion. Overall, the rapid device fabrication method achieved medium-volume production rates and was found to support both cell culture and experiments associated with measuring barrier and endothelial function. This fabrication method has potential to both accelerate biomicrofluidics and OOC research in the lab and accelerate development of commercialized microfluidic membrane devices