46 research outputs found
ΠΠ΅ΡΠΎΠ΄ΠΈΡΠ½Ρ Π²ΠΊΠ°Π·ΡΠ²ΠΊΠΈ Ρ ΠΊΠΎΠ½ΡΡΠΎΠ»ΡΠ½Ρ Π·Π°Π²Π΄Π°Π½Π½Ρ Π· ΠΊΡΡΡΡ "ΠΠΈΡΠΎΠΊΠΎΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ½Ρ ΡΠ΅ΠΏΠ»ΠΎΡΠ΅Ρ Π½ΠΎΠ»ΠΎΠ³ΡΡΠ½Ρ ΡΡΡΠ°Π½ΠΎΠ²ΠΊΠΈ"
ΠΠΈΡΠΎΠΊΠΎΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ½Ρ ΠΏΡΠΎΡΠ΅ΡΠΈ Ρ ΠΎΡΠ½ΠΎΠ²Π½ΠΈΠΌΠΈ ΡΠΎΠ±ΠΎΡΠΈΠΌΠΈ ΠΏΡΠΎΡΠ΅ΡΠ°ΠΌΠΈ Π² ΡΡΠ΄Ρ ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΡΡΠ½ΠΈΡ
Π²ΠΈΡΠΎΠ±Π½ΠΈΡΡΠ², ΡΠ°ΠΊΠΈΡ
, ΡΠΊ Π²ΠΈΡΠΎΠ±Π½ΠΈΡΡΠ²ΠΎ ΠΊΠΎΠΊΡΡ, ΡΠ°Π²ΡΠ½Ρ, ΡΡΠ°Π»Ρ ΡΠ° ΠΊΠΎΠ»ΡΠΎΡΠΎΠ²ΠΈΡ
ΠΌΠ΅ΡΠ°Π»ΡΠ², Π²ΠΈΠΏΠ°Π» ΠΊΠ΅ΡΠ°ΠΌΡΠΊΠΈ Ρ Π²ΠΎΠ³Π½Π΅ΡΡΠΈΠ²ΡΠ², Π²ΠΈΠΏΠ°Π» Π²βΡΠΆΡΡΠΈΡ
ΠΌΠ°ΡΠ΅ΡΡΠ°Π»ΡΠ², Π²Π°ΡΡΠ½Π½Ρ ΡΠΊΠ»Π°, Π²ΠΈΡΠΎΠΊΠΎΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ½Π΅ Π½Π°Π³ΡΡΠ²Π°Π½Π½Ρ Π·Π»ΠΈΡΠΊΡΠ², ΠΎΡΡΠΈΠΌΠ°Π½Π½Ρ Π°Π³Π»ΠΎΠΌΠ΅ΡΠ°ΡΡ, ΡΠ΅ΡΠΎΡΠΏΠ»Π°Π²ΡΠ² ΡΠ° ΡΠ½. Π£ ΠΏΡΠΎΡΠ΅ΡΡ Π²ΠΈΠ²ΡΠ΅Π½Π½Ρ Π΄ΠΈΡΡΠΈΠΏΠ»ΡΠ½ΠΈ Β«ΠΠΈΡΠΎΠΊΠΎΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ½Ρ ΡΡΡΠ°Π½ΠΎΠ²ΠΊΠΈΒ» (ΠΠ’Π£) Π½Π΅ΠΎΠ±Ρ
ΡΠ΄Π½ΠΎ ΠΎΡΠ²ΠΎΡΡΠΈ ΠΌΠ΅ΡΠΎΠ΄ΠΈ ΠΏΡΠ°ΠΊΡΠΈΡΠ½ΠΎΠ³ΠΎ ΡΠΎΠ·ΡΠ°Ρ
ΡΠ½ΠΊΡ ΡΠ΅ΠΏΠ»ΠΎΠ²ΠΎΠ³ΠΎ ΡΡΠ°Π½Ρ Π·Π»ΠΈΡΠΊΠ° Π² ΠΏΡΠΎΡΠ΅ΡΡ Π½Π°Π³ΡΡΠ²Π°Π½Π½Ρ, Π²ΠΈΠ·Π½Π°ΡΠΈΡΠΈ Π²ΠΏΠ»ΠΈΠ² ΠΎΠΊΡΠ΅ΠΌΠΈΡ
ΡΠ°ΠΊΡΠΎΡΡΠ² Π½Π° ΠΊΠ°Π»ΠΎΡΠΈΠΌΠ΅ΡΡΠΈΡΠ½Ρ, Π° Π²ΡΠ΄ΠΏΠΎΠ²ΡΠ΄Π½ΠΎ Ρ Π½Π° ΠΏΡΡΠΎΠΌΠ΅ΡΡΠΈΡΠ½y ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΡ Π³ΠΎΡΡΠ½Π½Ρ. ΠΠΌΡΡΠΈ ΡΠ°ΠΌΠΎΡΡΡΠΉΠ½ΠΎ Π²ΠΈΠ±ΡΠ°ΡΠΈ Π²ΠΎΠ³Π½Π΅ΡΡΠΈΠ²ΠΊΡ ΡΠ° ΡΠ·ΠΎΠ»ΡΡΡΠΉΠ½Ρ ΠΌΠ°ΡΠ΅ΡΡΠ°Π»ΠΈ Π΄Π»Ρ ΠΏΠ΅ΡΡ Π·Π°Π΄Π°Π½ΠΈΡ
ΡΠΎΠ·ΠΌΡΡΡΠ² Ρ ΡΠ΅ΠΏΠ»ΠΎΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΡΡΠ½ΠΈΡ
ΡΠΌΠΎΠ², ΡΠΊΠ»Π°ΡΡΠΈ ΡΠ΅ΠΏΠ»ΠΎΠ²ΠΈΠΉ Π±Π°Π»Π°Π½Ρ ΠΏΠ΅ΡΡ Ρ Π²ΠΈΠ·Π½Π°ΡΠΈΡΠΈ Π³ΠΎΠ΄ΠΈΠ½Π½Ρ, ΡΠ΅ΠΊΡΠ½Π΄Π½Ρ ΡΠ° ΠΏΠΈΡΠΎΠΌΡ Π²ΠΈΡΡΠ°ΡΡ Π·Π°Π΄Π°Π½ΠΎΠ³ΠΎ Ρ ΡΠΌΠΎΠ²Π½ΠΎΠ³ΠΎ ΠΏΠ°Π»ΠΈΠ²Π°. ΠΠ»Ρ ΡΠ΅ΡΠΌΡΡΠ½ΠΎΡ ΡΠΎΠ»ΡΠ½ΠΎΡ ΠΏΠ΅ΡΡ Π· Π΅Π»Π΅ΠΊΡΡΠΈΡΠ½ΠΈΠΌ Π½Π°Π³ΡΡΠ²Π°Π½Π½ΡΠΌ Π²ΠΈΠ·Π½Π°ΡΠΈΡΠΈ ΡΠ°Ρ ΡΠΎΠ·ΡΠ³ΡΡΠ²Ρ ΠΏΠ΅ΡΡ Π· Ρ
ΠΎΠ»ΠΎΠ΄Π½ΠΎΠ³ΠΎ ΡΡΠ°Π½Ρ ΠΏΡΠΈ Π²ΠΈΠΊΠΎΡΠΈΡΡΠ°Π½Π½Ρ Π² ΠΊΠ»Π°Π΄ΡΡ ΡΡΠ·Π½ΠΈΡ
Π²ΠΎΠ³Π½Π΅ΡΡΠΈΠ²ΡΠ². ΠΡΡΡΠ°Π²ΠΈΡΠΈ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠΈ ΡΠΎΠ·ΡΠ°Ρ
ΡΠ½ΠΊΡ Ρ ΠΎΡΡΠ½ΠΈΡΠΈ Π΅Π½Π΅ΡΠ³ΠΎΠ΅ΡΠ΅ΠΊΡΠΈΠ²Π½ΡΡΡΡ Π·Π°Ρ
ΠΎΠ΄ΡΠ². Π£ΡΡ Π·Π°Π²Π΄Π°Π½Π½Ρ ΠΎΡΠΎΡΠΌΠ»ΡΡΡΡΡΡ Π½Π° Π°ΡΠΊΡΡΠ°Ρ
ΡΠΎΡΠΌΠ°ΡΡ Π4 Π°Π±ΠΎ Π² ΠΎΠΊΡΠ΅ΠΌΠΈΡ
Π·ΠΎΡΠΈΡΠ°Ρ
Structure formation in active networks
Structure formation and constant reorganization of the actin cytoskeleton are
key requirements for the function of living cells. Here we show that a minimal
reconstituted system consisting of actin filaments, crosslinking molecules and
molecular-motor filaments exhibits a generic mechanism of structure formation,
characterized by a broad distribution of cluster sizes. We demonstrate that the
growth of the structures depends on the intricate balance between
crosslinker-induced stabilization and simultaneous destabilization by molecular
motors, a mechanism analogous to nucleation and growth in passive systems. We
also show that the intricate interplay between force generation, coarsening and
connectivity is responsible for the highly dynamic process of structure
formation in this heterogeneous active gel, and that these competing mechanisms
result in anomalous transport, reminiscent of intracellular dynamics
Collective dynamics of active cytoskeletal networks
Self organization mechanisms are essential for the cytoskeleton to adapt to
the requirements of living cells. They rely on the intricate interplay of
cytoskeletal filaments, crosslinking proteins and molecular motors. Here we
present an in vitro minimal model system consisting of actin filaments, fascin
and myosin-II filaments exhibiting pulsative collective long range dynamics.
The reorganizations in the highly dynamic steady state of the active gel are
characterized by alternating periods of runs and stalls resulting in a
superdiffusive dynamics of the network's constituents. They are dominated by
the complex competition of crosslinking molecules and motor filaments in the
network: Collective dynamics are only observed if the relative strength of the
binding of myosin-II filaments to the actin network allows exerting high enough
forces to unbind actin/fascin crosslinks. The feedback between structure
formation and dynamics can be resolved by combining these experiments with
phenomenological simulations based on simple interaction rules
Thermal conduction in cosmological SPH simulations
Thermal conduction in the intracluster medium has been proposed as a possible
heating mechanism for offsetting central cooling losses in rich clusters of
galaxies. In this study, we introduce a new formalism to model conduction in a
diffuse ionised plasma using smoothed particle hydrodynamics (SPH), and we
implement it in the parallel TreePM/SPH-code GADGET-2. We consider only
isotropic conduction and assume that magnetic suppression can be described in
terms of an effective conductivity, taken as a fixed fraction of the
temperature-dependent Spitzer rate. We also account for saturation effects in
low-density gas. Our formulation manifestly conserves thermal energy even for
individual and adaptive timesteps, and is stable in the presence of small-scale
temperature noise. This allows us to evolve the thermal diffusion equation with
an explicit time integration scheme along with the ordinary hydrodynamics. We
use a series of simple test problems to demonstrate the robustness and accuracy
of our method. We then apply our code to spherically symmetric realizations of
clusters, constructed under the assumptions of hydrostatic equilibrium and a
local balance between conduction and radiative cooling. While we confirm that
conduction can efficiently suppress cooling flows for an extended period of
time in these isolated systems, we do not find a similarly strong effect in a
first set of clusters formed in self-consistent cosmological simulations.
However, their temperature profiles are significantly altered by conduction, as
is the X-ray luminosity.Comment: 14 pages, 7 figures, accepted by MNRAS, high resolution version
available at http://www.mpa-garching.mpg.de/~jubelgas/conduction.pdf. Fixed
typos in eq. 20,22,2
Morphological Multiscale Shape Analysis of Light Micrographs
Shape analysis of light--micrographs of cell populations is important for cytotoxicity evaluation. This paper presents a morphological method for quantitative analysis of shape deformations of cells in contact to a biomaterial. After illumination normalization, a morphological multiscale segmentation yields separated cells. Shape deformation, and hence, toxicity of the substance under scrutiny, is quantified by means of compactness distribution and pattern spectrum of the population. Since the logarithmic image model is applicable to transmitted light, illumination normalization is achieved by removing the illumination component from the log--image by a tophat transform utilizing a large reconstruction filter. Subsequent thresholding and noise filtering yields connected binary cells, which are segmented by a marker--based, multiscale approach. For this, size--specific marker scales are generated removing noise and false markers. Each cell is now represented by an isolated marker. Conve..