TY  - JOUR
A1  - Thapa, Samudrajit
A1  - Lukat, Nils
A1  - Selhuber-Unkel, Christine
A1  - Cherstvy, Andrey G.
A1  - Metzler, Ralf
T1  - Transient superdiffusion of polydisperse vacuoles in highly motile amoeboid cells
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2  - We perform a detailed statistical analysis of diffusive trajectories of membrane-enclosed vesicles (vacuoles) in the supercrowded cytoplasm of living Acanthamoeba castellanii cells. From the vacuole traces recorded in the center-of-area frame of moving amoebae, we examine the statistics of the time-averaged mean-squared displacements of vacuoles, their generalized diffusion coefficients and anomalous scaling exponents, the ergodicity breaking parameter, the non-Gaussian features of displacement distributions of vacuoles, the displacement autocorrelation function, as well as the distributions of speeds and positions of vacuoles inside the amoeba cells. Our findings deliver novel insights into the internal dynamics of cellular structures in these infectious pathogens. Published under license by AIP Publishing.
Y1  - 2019
U6  - https://doi.org/10.1063/1.5086269
SN  - 0021-9606
SN  - 1089-7690
VL  - 150
IS  - 14
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Krapf, Diego
A1  - Lukat, Nils
A1  - Marinari, Enzo
A1  - Metzler, Ralf
A1  - Oshanin, Gleb
A1  - Selhuber-Unkel, Christine
A1  - Squarcini, Alessio
A1  - Stadler, Lorenz
A1  - Weiss, Matthias
A1  - Xu, Xinran
T1  - Spectral Content of a Single Non-Brownian Trajectory
JF  - Physical review : X, Expanding access
N2  - Time-dependent processes are often analyzed using the power spectral density (PSD) calculated by taking an appropriate Fourier transform of individual trajectories and finding the associated ensemble average. Frequently, the available experimental datasets are too small for such ensemble averages, and hence, it is of a great conceptual and practical importance to understand to which extent relevant information can be gained from S(f, T), the PSD of a single trajectory. Here we focus on the behavior of this random, realization-dependent variable parametrized by frequency f and observation time T, for a broad family of anomalous diffusions-fractional Brownian motion with Hurst index H-and derive exactly its probability density function. We show that S(f, T) is proportional-up to a random numerical factor whose universal distribution we determine-to the ensemble-averaged PSD. For subdiffusion (H < 1/2), we find that S(f, T) similar to A/f(2H+1) with random amplitude A. In sharp contrast, for superdiffusion (H > 1/2) S(f, T) similar to BT2H-1/f(2) with random amplitude B. Remarkably, for H > 1/2 the PSD exhibits the same frequency dependence as Brownian motion, a deceptive property that may lead to false conclusions when interpreting experimental data. Notably, for H > 1/2 the PSD is ageing and is dependent on T. Our predictions for both sub-and superdiffusion are confirmed by experiments in live cells and in agarose hydrogels and by extensive simulations.
KW  - Biological Physics
KW  - Interdisciplinary Physics
KW  - Statistical Physics
Y1  - 2019
U6  - https://doi.org/10.1103/PhysRevX.9.011019
SN  - 2160-3308
VL  - 9
IS  - 1
PB  - American Physical Society
CY  - College Park
ER  -