Entropic forces in Brownian motion

Roos, Nico

doi:10.1119/1.4894381

Cited by 36 publications

(31 citation statements)

References 13 publications

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“…As can be seen from Fig. 7C and D, in the simulations the step size distribution is well represented by a normal distribution, as expected for a process of entropic segregation (35). However, the experimental step size distribution (shown in Fig.…”

Section: Figsupporting

confidence: 76%

Chromosome Segregation in Bacillus subtilis Follows an Overall Pattern of Linear Movement and Is Highly Robust against Cell Cycle Perturbations

Najjar

Geisel

Schmidt

et al. 2020

mSphere

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Although several proteins have been identified that facilitate chromosome segregation in bacteria, no clear analogue of the mitotic machinery in eukaryotic cells has been identified. In order to investigate if recognizable patterns of segregation exist during the cell cycle, we tracked the segregation of duplicated origin regions in Bacillus subtilis for 60 min in the fastest practically achievable resolution, achieving 10-s intervals. We found that while separation occurred in random patterns, often including backwards movement, overall, segregation of loci near the origins of replication was linear for the entire cell cycle. Thus, the process of partitioning can be best described as directed motion. Simulations with entropy-driven separation of polymers synthesized by two polymerases show sudden bursts of movement and segregation patterns compatible with the observed in vivo patterns, showing that for Bacillus, segregation patterns can be modeled based on entropic forces. To test if obstacles for replication forks lead to an alteration of the partitioning pattern, we challenged cells with chemicals inducing DNA damage or blocking of topoisomerase activity. Both treatments led to a moderate slowing down of separation, but linear segregation was retained, showing that chromosome segregation is highly robust against cell cycle perturbation. IMPORTANCE We have followed the segregation of origin regions on the Bacillus subtilis chromosome in the fastest practically achievable temporal manner, for a large fraction of the cell cycle. We show that segregation occurred in highly variable patterns but overall in an almost linear manner throughout the cell cycle. Segregation was slowed down, but not arrested, by treatment of cells that led to transient blocks in DNA replication, showing that segregation is highly robust against cell cycle perturbation. Computer simulations based on entropy-driven separation of newly synthesized DNA polymers can recapitulate sudden bursts of movement and segregation patterns compatible with the observed in vivo patterns, indicating that for Bacillus, segregation patterns may include entropic forces helping to separate chromosomes during the cell cycle.

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Section: Figsupporting

confidence: 76%

Chromosome Segregation in Bacillus subtilis Follows an Overall Pattern of Linear Movement and Is Highly Robust against Cell Cycle Perturbations

Najjar

Geisel

Schmidt

et al. 2020

mSphere

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“…The force acting on price can therefore be viewed as a linear entropic force (Sokolov, 2010;Roos, 2014) with force constant k = k B T/ σ 2 , which acts to restore the price to the preferred central point.…”

Section: Quantize Thismentioning

confidence: 99%

Quantum‐tative Finance

Orrell¹

2020

Wilmott

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“…), particle velocity, and blood viscosity (3 mPa.s). In order to develop a realistic model at body temperature (37 °C), we exerted random Brownian force ( F B ) whose equations were mentioned in Roos []. These involved forces provide realistic conditions to address the steering capability of the proposed patterning scheme.…”

Section: Spatial Fourier Spectrummentioning

confidence: 99%

Magnetic field pattern synthesis and its application in targeted drug delivery: Design and implementation

Hajiaghajani

Abdolali

2018

Bioelectromagnetics

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In cancer therapy, magnetic drug targeting is considered as an effective treatment to reduce chemotherapy's side effects. The accurate design and shaping of magnetic fields are crucial for healthy cells to be immune from chemotherapeutics. In this paper, arbitrary 2-dimensional spatial patterns of magnetic fields from DC to megahertz are represented in terms of spatial Fourier spectra with sinusoidal eigenfunctions. Realization of each spatial frequency was investigated by a set of elliptical coils. Therefore, it is shown that the desired pattern was synthesized by simultaneous use of coil sets. Currents running on each set were obtained via fast and straightforward analytical Fourier series calculation. Experimentally scanned sample patterns were in close agreement with full wave analysis. Discussions include the evaluation of the Fourier series approximation error and cross-polarization of produced magnetic fields. It was observed that by employing the controlled magnetic field produced by the proposed setup, we were able to steer therapeutic particles toward the right or left half-spheres of the breast, with an efficiency of 90%. Such a pattern synthesizer may be employed in numerous human arteries as well as other bioelectromagnetic patterning applications, e.g., wireless power transfer, magnetic innervation, and tomography. Bioelectromagnetics. 39:325-338, 2018. © 2018 Wiley Periodicals, Inc.

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Entropic forces in Brownian motion

Cited by 36 publications

References 13 publications

Chromosome Segregation in Bacillus subtilis Follows an Overall Pattern of Linear Movement and Is Highly Robust against Cell Cycle Perturbations

Chromosome Segregation in Bacillus subtilis Follows an Overall Pattern of Linear Movement and Is Highly Robust against Cell Cycle Perturbations

Quantum‐tative Finance

Magnetic field pattern synthesis and its application in targeted drug delivery: Design and implementation

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