The road not taken by a traveling drop
We have successfully explained the time-dependent behavior of the traffic of discrete objects within a simple network. Although our study focuses on the dynamic behavior of micron-sized liquid droplets at a fork, the reasoning behind the model we derived may be employed in confronting other challenges, from planning vehicular traffic in modern cities to routing data over the internet. Our results concerning droplet traffic at a bifurcation should provide a breakthrough for the development of the type of lab-on-a-chip technology used nowadays. For example, in high-throughput screening for drug development, the use of passive control, sorting, and storage of individual droplets, would eliminate the need for complicated micromechanical valves or pumps. The model derived in our paper, which describes the periodic dynamic behavior of droplets travelling in a splitting channel, provides rules for the "choice" of which path to follow. These selection rules are successfully compared to simulations and experiments.
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LT12935
The Clapping Book: wind-driven oscillations in a stack of elastic sheets
We present a hybrid experimental and theoretical study on the oscillatory behavior exhibited by multiple thin sheets under aerodynamic loading. Our clapping book consists of a stack of paper, clamped at the downstream end, placed in a wind tunnel with steady flow. As pages lift off , they accumulate onto a bent stack held up by the wind. The book collapses shut once the elasticity and weight of the pages overcome the aerodynamic force. The process then repeats periodically. We develop a theoretical model that predictively describes this robust oscillatory behavior.
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LU12503
Hawking radiation from ultrashort laser pulse filaments
Event horizons of astrophysical black holes and gravitational analogues have been predicted to excite the quantum vacuum and give rise to the emission of quanta, known as Hawking radiation. We experimentally create such a gravitational analogue using ultrashort laser pulse filaments and our measurements demonstrate a spontaneous emission of photons that confirms theoretical predictions.
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LS12383
Modeling Online Popularity
The purpose of this paper is to offer a massive quantitative, global, and longitudinal analysis of the processes driving the acquisition of popularity in the online world. To this end the study analyzes large-scale datasets that are representative of the Web by capturing the online behaviors of millions of people and sheds light for the first time onto the manner in which collective attention manifest itself through bursts which are both violent in magnitude and unpredictable – much like online earthquakes. However, the model provided is capable of reproducing all of the observed dynamics of online popularity through a mechanism that causes sudden, nonlinear bursts of collective attention. Given the increasing number of activities carried out online and the effect that large-scale opinion formation has on important phenomena like public policy, culture, and advertising profits, such a quantitative picture of online human activity will only become more pertinent in the coming years.
