Comparison test of website use with mobile phone and laptop computer

The study compared user performance and subjective ratings between a mobile phone and laptop computer for accessing the internet. Twenty four participants were required to carry out two equivalent sets of 5 tasks, one set of tasks with a mobile phone and the other set with a laptop. It was found that the task times for the mobile phone were higher than those of the laptop for all tasks but only significantly different for two of the task pairs. The most important reason for this result seemed to be the difference in size of the screens on each device. Participants were also asked to rate the difficulty of each task performed on both laptop and phone. Interestingly, participants did not rate the difficulty of using the mobile phone significantly higher than for the laptop. This seemed to be because of lower expectations when using the mobile phone, good dexterity in zooming in and out of the screen, and spending less time reviewing each page on the phone than on the laptop before moving on another page

The role of intracellular signaling in the stripe formation in engineered <i>Escherichia coli</i> populations

<div><p>Recent experiments showed that engineered <i>Escherichia coli</i> colonies grow and self-organize into periodic stripes with high and low cell densities in semi-solid agar. The stripes develop sequentially behind a radially propagating colony front, similar to the formation of many other periodic patterns in nature. These bacteria were created by genetically coupling the intracellular chemotaxis pathway of wild-type cells with a quorum sensing module through the protein CheZ. In this paper, we develop multiscale models to investigate how this intracellular pathway affects stripe formation. We first develop a detailed hybrid model that treats each cell as an individual particle and incorporates intracellular signaling via an internal ODE system. To overcome the computational cost of the hybrid model caused by the large number of cells involved, we next derive a mean-field PDE model from the hybrid model using asymptotic analysis. We show that this analysis is justified by the tight agreement between the PDE model and the hybrid model in 1D simulations. Numerical simulations of the PDE model in 2D with radial symmetry agree with experimental data semi-quantitatively. Finally, we use the PDE model to make a number of testable predictions on how the stripe patterns depend on cell-level parameters, including cell speed, cell doubling time and the turnover rate of intracellular CheZ.</p></div

Autogenous Metallic Pipe Leak Repair in Potable Water Systems

Copper and iron pipes have a remarkable capability for autogenous repair (self-repair) of leaks in potable water systems. Field studies revealed exemplars that metallic pipe leaks caused by nails, rocks, and erosion corrosion autogenously repaired, as confirmed in the laboratory experiments. This work demonstrated that 100% (<i>N</i> = 26) of 150 μm leaks contacting representative bulk potable water in copper pipes sealed autogenously via formation of corrosion precipitates at 20–40 psi, pH 3.0–11.0, and with upward and downward leak orientations. Similar leaks in carbon steel pipes at 20 psi self-repaired at pH 5.5 and 8.5, but two leaks did not self-repair permanently at pH 11.0 suggesting that water chemistry may control the durability of materials that seal the leaks and therefore the permanence of repair. Larger 400 μm holes in copper pipes had much lower (0–33%) success of self-repair at pH 3.0–11.0, whereas all 400 μm holes in carbon steel pipes at 20 psi self-repaired at pH 4.0–11.0. Pressure tests indicated that some of the repairs created at 20–40 psi ambient pressure could withstand more than 100 psi without failure. Autogenous repair has implications for understanding patterns of pipe failures, extending the lifetime of decaying infrastructure, and developing new plumbing materials

Schematic illustration of the front speed, wavelength, height ratio and density ratio.

<p>Schematic illustration of the front speed, wavelength, height ratio and density ratio.</p

Concentric stripe patterns in 2D predicted by the PDE model.

<p>(A) spatial density plots at <i>t</i> = 2.5h, <i>t</i> = 6.5h, <i>t</i> = 8.5h, <i>t</i> = 10.5h and <i>t</i> = 12.5h. (B) Dynamics of the cell density in the radial direction predicted by the PDE model. (C) Dynamics of the cell density in the radial direction measured in experiments. (C) Reproduced from Fig. S3 in SOM of Liu et al, Science, Vol 334, 238–241, 2011 [<a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1006178#pcbi.1006178.ref012" target="_blank">12</a>]. Parameters used here are either directly taken from Tables <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1006178#pcbi.1006178.t001" target="_blank">1</a>–<a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1006178#pcbi.1006178.t003" target="_blank">3</a> or calculated using the conversion formulas.</p

Online_Appendices – Supplemental material for Creating Democratic Citizens: Political Effects of the Internet in China

<p>Supplemental material, Online_Appendices for Creating Democratic Citizens: Political Effects of the Internet in China by Narisong Huhe, Min Tang and Jie Chen in Political Research Quarterly</p

Dependence of intracellular signaling on total CheZ.

<p>(A) <i>Y</i>_<i>p</i> as a function of <i>Z</i>_<i>t</i> and <i>m</i>. (B) the stationary methylation level <i>m</i>* as a function of <i>Z</i>_<i>t</i>; (C) the stationary CheYp concentration given different <i>Z</i>_<i>t</i>. Parameter values are the same as in <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1006178#pcbi.1006178.t001" target="_blank">Table 1</a>.</p

Huhe_Replication_Data – Supplemental material for Creating Democratic Citizens: Political Effects of the Internet in China

<p>Supplemental material, Huhe_Replication_Data for Creating Democratic Citizens: Political Effects of the Internet in China by Narisong Huhe, Min Tang and Jie Chen in Political Research Quarterly</p

The cell density profile for different CheZ turnover rate <i>κ</i>.

<p>(A) Spatial density plots at <i>t</i> = 20h with <i>κ</i> = 0.1, 0.6, 1, 10, respectively. (B) Dependence of the front speed and wavelength on <i>κ</i>. (C) Dependence of the height ratio and density ratio on <i>κ</i>. (D) Plots of <i>ρ</i>(<i>ξ</i>, 20) for <i>κ</i> = 0.6 and 10. All other parameters are the same as in <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1006178#pcbi.1006178.g007" target="_blank">Fig 7</a>.</p

Parameters for AHL and the nutrient.

<p>Parameters for AHL and the nutrient.</p