Active Brownian motion with intermittent direction reversals is common in bacteria like Myxococcus xanthus and Pseudomonas putida. We show that, for such a motion in two dimensions, the presence of the two timescales set by the rotational diffusion constant D_{R} and the reversal rate γ gives rise to four distinct dynamical regimes: (I) t≪min(γ^{-1},D_{R}^{-1}), (II) γ^{-1}≪t≪D_{R}^{-1}, (III) D_{R}^{-1}≪t≪γ^{-1}, and (IV) t≫max(γ^{-1}, D_{R}^{-1}), showing distinct behaviors. We characterize these behaviors by analytically computing the position distribution and persistence exponents. The position distribution shows a crossover from a strongly nondiffusive and anisotropic behavior at short times to a diffusive isotropic behavior via an intermediate regime, II or III. In regime II, we show that, the position distribution along the direction orthogonal to the initial orientation is a function of the scaled variable z∝x_{⊥}/t with a nontrivial scaling function, f(z)=(2π^{3})^{-1/2}Γ(1/4+iz)Γ(1/4-iz). Furthermore, by computing the exact first-passage time distribution, we show that a persistence exponent α=1 emerges due to the direction reversal in this regime.

Download full-text PDF

Source
http://dx.doi.org/10.1103/PhysRevE.104.L012601DOI Listing

Publication Analysis

Top Keywords

position distribution
12
active brownian
8
brownian motion
8
distribution persistence
8
motion directional
4
directional reversals
4
reversals active
4
motion intermittent
4
intermittent direction
4
direction reversals
4

Similar Publications

Individuals diagnosed with Castleman disease (CD) and TAFRO syndrome (characterized by thrombocytopenia, anasarca, fever, bone marrow fibrosis, and organomegaly) displays a wide range of clinical symptoms, including varying patterns of lymph node enlargement, systemic inflammation, and impaired organ function. Some patients may present with both CD and TAFRO syndrome concurrently. A retrospective study conducted across multiple centers in Japan examined 321 cases to determine if the quantity and position of swollen lymph nodes could forecast the clinical progression and intensity of these conditions.

View Article and Find Full Text PDF

In developing tissues, the number, position, and differentiation of cells must be coordinately controlled to ensure the emergence of physiological function. The epidermis of the Xenopus embryo contains thousands of uniformly distributed multiciliated cells (MCCs), which grow hundreds of coordinately polarized cilia that beat vigorously to generate superficial water flow. Using this model, we uncovered a dual role for the conserved centriolar component Odf2, in MCC apical organization at the cell level, and in MCC spatial distribution at the tissue level.

View Article and Find Full Text PDF

Effects of routine postural repositioning on the distribution of lung ventilation and perfusion in mechanically ventilated patients.

Intensive Crit Care Nurs

January 2025

Department of Intensive Care Medicine, Hospital Universitario de La Princesa, Madrid, Spain; Centro de investigación en red CIBERES de enfermedades respiratorias, Instituto de Salud, Carlos III, Madrid, Spain. Electronic address:

Objectives: To analyse the effects on respiratory function, lung volume and the regional distribution of ventilation and perfusion of routine postural repositioning in mechanically ventilated critically ill patients.

Methods: Prospective descriptive physiological study. We evaluated gas-exchange, lung mechanics, and Electrical Impedance Tomography (EIT) determined end-expiratory lung impedance and regional ventilation and perfusion distribution in five body positions: supine-baseline (S1); first lateralisation at 30° (L1); second supine position (S2), second contralateral lateralisation (L2) and third final supine position (S3).

View Article and Find Full Text PDF

Purpose: The fixation method commonly employed worldwide for treating unstable fractures of the posterior pelvic ring is the percutaneous iliosacral screw technique. However, prolonged operation time and frequent fluoroscopies result in surgical risks. This study aimed to investigate whether a new triangulation method could reduce operative and fluoroscopy times and increase the accuracy of screw placement.

View Article and Find Full Text PDF

Purpose: To use swept-source optical coherence tomography angiography (SS-OCTA) to investigate the alterations in retinal vascular density (VD) in patients presenting with congenital unilateral trochlear nerve palsy.

Methods: The medical records of patients diagnosed with congenital unilateral trochlear nerve palsy and those of a healthy control group were reviewed retrospectively. Comprehensive ocular examinations and SS-OCTA imaging were conducted.

View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!