Vesicle shape transformations driven by confined active filaments

AbstractIn active matter systems, deformable boundaries provide a mechanism to organize internal active stresses. To study a minimal model of such a system, we perform particle-based simulations of an elastic vesicle containing a collection of polar active filaments. The interplay between the active stress organization due to interparticle interactions and that due to the deformability of the confinement leads to a variety of filament spatiotemporal organizations that have not been observed in bulk systems or under rigid confinement, including highly-aligned rings and caps. In turn, these filament assemblies drive dramatic and tunable transformations of the vesicle shape and its dynamics. We present simple scaling models that reveal the mechanisms underlying these emergent behaviors and yield design principles for engineering active materials with targeted shape dynamics.

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Dynamics of CO2 laser heated solenoids

Canadian Journal of Physics ◽

10.1139/p82-171 ◽

1982 ◽

Vol 60 (9) ◽

pp. 1247-1256 ◽

Cited By ~ 2

Author(s):

D. C. D. McKen ◽

W. Tighe ◽

R. Fedosejevs ◽

A. A. Offenberger

Keyword(s):

Laser Energy ◽

Plasma Temperature ◽

Wave Model ◽

Hydrogen Gas ◽

Pressure Balance ◽

Scaling Models ◽

Simple Scaling ◽

Gas Breakdown ◽

Long Pulse ◽

Laser Heated

Experimental results are reported for long pulse CO2 laser production and heating of magnetically confined plasma columns. The plasma column is produced by an ionizing and heating wave propagation along the axis of a linear magnetic solenoid when laser radiation is focused into hydrogen gas contained inside the solenoid. The axial behavior is found to be reasonably well described by a "bleaching" wave model which predicts column length as a function of time. Radial behavior, following a transient ionization and expansion phase, is determined by a balance of ion thermal conduction and inverse bremsstrahlung laser heating. A finite ionization time is observed at the gas breakdown front. Energy balance measurements indicate that most of the incident laser energy is effectively coupled to ionization and heating of the plasma. Temperature measurements show good agreement with predictions of simple scaling models from which pressure balance gives a density value in agreement with experiment.

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Comparison of Local, Regional, and Scaling Models for Rainfall Intensity–Duration–Frequency Analysis

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-20-0094.1 ◽

2020 ◽

Vol 59 (9) ◽

pp. 1519-1536

Author(s):

Giuseppe Mascaro

Keyword(s):

Monte Carlo ◽

High Resolution ◽

Annual Rainfall ◽

Return Periods ◽

Rain Gauges ◽

Scaling Models ◽

Simple Scaling ◽

Daily Scale ◽

Intensity Duration Frequency ◽

Rainfall Statistics

AbstractIntensity–duration–frequency (IDF) analyses of rainfall extremes provide critical information to mitigate, manage, and adapt to urban flooding. The accuracy and uncertainty of IDF analyses depend on the availability of historical rainfall records, which are more accessible at daily resolution and, quite often, are very sparse in developing countries. In this work, we quantify performances of different IDF models as a function of the number of available high-resolution (Nτ) and daily (N24h) rain gauges. For this aim, we apply a cross-validation framework that is based on Monte Carlo bootstrapping experiments on records of 223 high-resolution gauges in central Arizona. We test five IDF models based on (two) local, (one) regional, and (two) scaling frequency analyses of annual rainfall maxima from 30-min to 24-h durations with the generalized extreme value (GEV) distribution. All models exhibit similar performances in simulating observed quantiles associated with return periods up to 30 years. When Nτ > 10, local and regional models have the best accuracy; bias correcting the GEV shape parameter for record length is recommended to estimate quantiles for large return periods. The uncertainty of all models, evaluated via Monte Carlo experiments, is very large when Nτ ≤ 5; however, if N24h ≥ 10 additional daily gauges are available, the uncertainty is greatly reduced and accuracy is increased by applying simple scaling models, which infer estimates on subdaily rainfall statistics from information at daily scale. For all models, performances depend on the ability to capture the elevation control on their parameters. Although our work is site specific, its results provide insights to conduct future IDF analyses, especially in regions with sparse data.

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Stochasting modeling of planetary ring systems

International Astronomical Union Colloquium ◽

10.1017/s025292110010154x ◽

1984 ◽

Vol 75 ◽

pp. 461-469 ◽

Cited By ~ 1

Author(s):

Robert W. Hart

Keyword(s):

Maximum Entropy ◽

Ring System ◽

The Sun ◽

Ultimate State ◽

Interparticle Interactions ◽

Ring Systems ◽

First Order ◽

Planetary Ring ◽

Insight Into

ABSTRACTThis paper models maximum entropy configurations of idealized gravitational ring systems. Such configurations are of interest because systems generally evolve toward an ultimate state of maximum randomness. For simplicity, attention is confined to ultimate states for which interparticle interactions are no longer of first order importance. The planets, in their orbits about the sun, are one example of such a ring system. The extent to which the present approximation yields insight into ring systems such as Saturn's is explored briefly.

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