Results 11 to 20 of about 64,828 (125)
Hydro-osmotic instabilities in active membrane tubes [PDF]
Phys. Rev. Lett. 120, 138102 (2018), 2017 We study a membrane tube with unidirectional ion pumps driving an osmotic pressure difference. A pressure driven peristaltic instability is identified, qualitatively distinct from similar tension-driven Rayleigh type instabilities on membrane tubes.
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Genetic Neural Architecture Search for automatic assessment of human sperm images [PDF]
Expert Systems with Applications, 2021, 2019 Male infertility is a disease which affects approximately 7% of men. Sperm morphology analysis (SMA) is one of the main diagnosis methods for this problem. Manual SMA is an inexact, subjective, non-reproducible, and hard to teach process. As a result, in this paper, we introduce a novel automatic SMA based on a neural architecture search algorithm ...
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First order perturbations of the Einstein-Straus and Oppenheimer-Snyder models [PDF]
Phys.Rev.D78:084022,2008, 2008 We derive the linearly perturbed matching conditions between a Schwarzschild spacetime region with stationary and axially symmetric perturbations and a FLRW spacetime with arbitrary perturbations. The matching hypersurface is also perturbed arbitrarily and, in all cases, the perturbations are decomposed into scalars using the Hodge operator on the ...
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Light bending by the cosmological constant [PDF]
, 2021 We revisit the question of whether the cosmological constant $\Lambda$ affects the cosmological gravitational bending of light, by numerical integration of the geodesic equations for a Swiss cheese model consisting of a point mass and a compensated vacuole, in a Friedmann-Robertson-Walker background. We find that there is virtually no dependence of the
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Metric Expansion from Microscopic Dynamics in an Inhomogeneous Universe [PDF]
Communications in Theoretical Physics 54 (3) pp. 477-483 (2010), 2010 Theories with ingredients like the Higgs mechanism, gravitons, and inflaton fields rejuvenate the idea that relativistic kinematics is dynamically emergent. Eternal inflation treats the Hubble constant H as depending on location. Microscopic dynamics implies that H is over much smaller lengths than pocket universes to be understood as a local space ...
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Review on exact and perturbative deformations of the Einstein-Straus model: uniqueness and rigidity results [PDF]
, 2013 The Einstein-Straus model consists of a Schwarzschild spherical vacuole in a Friedman-Lema\^{\i}tre-Robertson-Walker (FLRW) dust spacetime (with or without \Lambda). It constitutes the most widely accepted model to answer the question of the influence of large scale (cosmological) dynamics on local systems.
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A New Type of Exact Arbitrarily Inhomogeneous Cosmology: Evolution of Deceleration in the Flat Homogeneous-On-Average Case [PDF]
Journal of Cosmology and Astroparticle Physics, JCAP01(2012)043, 2012 A new method for constructing exact inhomogeneous universes is presented, that allows variation in 3 dimensions. The resulting spacetime may be statistically uniform on average, or have random, non-repeating variation. The construction utilises the Darmois junction conditions to join many different component spacetime regions.
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Spherical steady accretion flows -- dependence on the cosmological constant, exact isothermal solutions and applications to cosmology [PDF]
Phys. Rev. D 88, 084056 (2013), 2013 We investigate spherical, isothermal and polytropic steady accretion models in the presence of the cosmological constant. Exact solutions are found for three classes of isothermal fluids, assuming the test gas approximation. The cosmological constant damps the mass accretion rate and - above certain limit - completely stops the steady accretion onto ...
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Measurement of Cytoplasmic Streaming in Chara Corallina by Magnetic Resonance Velocimetry [PDF]
, 2009 In aquatic plants such as the Characean algae, the force generation that drives cyclosis is localized within the cytoplasm, yet produces fluid flows throughout the vacuole. For this to occur the tonoplast must transmit hydrodynamic shear efficiently. Here, using magnetic resonance velocimetry, we present the first whole-cell measurements of the cross ...
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Regulatory assembly of the vacuolar proton pump VOV1-ATPase in yeast cells by FLIM-FRET [PDF]
, 2010 We investigate the reversible disassembly of VOV1-ATPase in life yeast cells by time resolved confocal FRET imaging. VOV1-ATPase in the vacuolar membrane pumps protons from the cytosol into the vacuole. VOV1-ATPase is a rotary biological nanomotor driven by ATP hydrolysis.
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