107 research outputs found
DSMC evaluation of the Navier-Stokes shear viscosity of a granular fluid
A method based on the simple shear flow modified by the introduction of a
deterministic non-conservative force and a stochastic process is proposed to
measure the Navier-Stokes shear viscosity in a granular fluid described by the
Enskog equation. The method is implemented in DSMC simulations for a wide range
of values of dissipation and density. It is observed that, after a certain
transient period, the system reaches a hydrodynamic stage which tends to the
Navier-Stokes regime for long times. The results are compared with theoretical
predictions obtained from the Chapman-Enskog method in the leading Sonine
approximation, showing quite a good agreement, even for strong dissipation.Comment: 6 pages, 4 figures; to appear in Rarefied Gas Dynamics: 24th
International Symposium (AIP Conference Proceedings
Breakdown of Energy Equipartition in a 2D Binary Vibrated Granular Gas
We report experiments on the equipartition of kinetic energy between grains
made of two different materials in a mixture of grains vibrated in 2
dimensions. In general, the two types of grains do not attain the same granular
temperature, Tg = 1/2m v^2. However, the ratio of the two temperatures is
constant in the bulk of the system and independent of the vibration velocity.
The ratio depends strongly on the ratio of mass densities of the grains, but is
not sensitive to the inelasticity of grains. Also, this ratio is insensitive to
compositional variables of the mixture such as the number fraction of each
component and the total number density. We conclude that a single granular
temperature, as traditionally defined, does not characterize a multi-component
mixture.Comment: 4 pages, 5 figures, submitted to Physical Review Letters, updated
reference
Structural requirements for protection by small amino acids against hypoxic injury in kidney proximal tubules1
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154313/1/fsb2004015011.pd
HoMEcare aRm rehabiLItatioN (MERLIN): telerehabilitation using an unactuated device based on serious games improves the upper limb function in chronic stroke
HoMEcare aRm rehabiLItatioN (MERLIN) is an unactuated version of the robotic device ArmAssist combined with a telecare platform. Stroke patients are able to train the upper limb function using serious games at home. The aim of this study is to investigate the effect of MERLIN training on the upper limb function of patients with unilateral upper limb paresis in the chronic phase of stroke (> 6 months post stroke).
Patients trained task specific serious games for three hours per week during six weeks using an unactuated version of a robotic device. Progress was monitored and game settings were tailored through telerehabilitation. Measurements were performed six weeks pre-intervention (T0), at the start (T1), end (T2) and six weeks post-intervention (T3). Primary outcome was the Wolf Motor Function Test (WMFT). Secondary outcomes were other arm function tests, quality of life, user satisfaction and motivation.This research is part of MERLIN project (19094 and 20649) that has received funding from EIT Health. EIT Health is supported by the European Institute of Innovation and Technology (EIT), a body of the European Union receives support from the European Union´s Horizon 2020 Research and innovation program
Golexanolone improves fatigue, motor incoordination and gait and memory in rats with bile duct ligation
\ua9 2023 The Authors. Liver International published by John Wiley & Sons Ltd.Background and Aims: Many patients with the chronic cholestatic liver disease primary biliary cholangitis (PBC) show fatigue and cognitive impairment that reduces their quality of life. Likewise, rats with bile duct ligation (BDL) are a model of cholestatic liver disease. Current PBC treatments do not improve symptomatic alterations such as fatigue or cognitive impairment and new, more effective treatments are therefore required. Golexanolone reduces the potentiation of GABAA receptors activation by neurosteroids. Golexanolone reduces peripheral inflammation and neuroinflammation and improves cognitive and motor function in rats with chronic hyperammonemia. The aims of the present study were to assess if golexanolone treatment improves fatigue and cognitive and motor function in cholestatic BDL rats and if this is associated with improvement of peripheral inflammation, neuroinflammation, and GABAergic neurotransmission in the cerebellum. Methods: Rats were subjected to bile duct ligation. One week after surgery, oral golexanolone was administered daily to BDL and sham-operated controls. Fatigue was analysed in the treadmill, motor coordination in the motorater, locomotor gait in the Catwalk, and short-term memory in the Y-maze. We also analysed peripheral inflammation, neuroinflammation, and GABAergic neurotransmission markers by immunohistochemistry and Western blot. Results: BDL induces fatigue, impairs memory and motor coordination, and alters locomotor gait in cholestatic rats. Golexanolone improves these alterations, and this was associated with improvement of peripheral inflammation, neuroinflammation, and GABAergic neurotransmission in the cerebellum. Conclusion: Golexanolone may have beneficial effects to treat fatigue, and motor and cognitive impairment in patients with the chronic cholestatic liver disease PBC
Self-diffusion in dense granular shear flows
Diffusivity is a key quantity in describing velocity fluctuations in granular
materials. These fluctuations are the basis of many thermodynamic and
hydrodynamic models which aim to provide a statistical description of granular
systems. We present experimental results on diffusivity in dense, granular
shear in a 2D Couette geometry. We find that self-diffusivities are
proportional to the local shear rate with diffusivities along the mean flow
approximately twice as large as those in the perpendicular direction. The
magnitude of the diffusivity is D \approx \dot\gamma a^2 where a is the
particle radius. However, the gradient in shear rate, coupling to the mean
flow, and drag at the moving boundary lead to particle displacements that can
appear sub- or super-diffusive. In particular, diffusion appears superdiffusive
along the mean flow direction due to Taylor dispersion effects and subdiffusive
along the perpendicular direction due to the gradient in shear rate. The
anisotropic force network leads to an additional anisotropy in the diffusivity
that is a property of dense systems with no obvious analog in rapid flows.
Specifically, the diffusivity is supressed along the direction of the strong
force network. A simple random walk simulation reproduces the key features of
the data, such as the apparent superdiffusive and subdiffusive behavior arising
from the mean flow, confirming the underlying diffusive motion. The additional
anisotropy is not observed in the simulation since the strong force network is
not included. Examples of correlated motion, such as transient vortices, and
Levy flights are also observed. Although correlated motion creates velocity
fields qualitatively different from Brownian motion and can introduce
non-diffusive effects, on average the system appears simply diffusive.Comment: 13 pages, 20 figures (accepted to Phys. Rev. E
Motor neuron differentiation of iPSCs obtained from peripheral blood of a mutant TARDBP ALS patient
Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative disease, mainly affecting the motor neurons (MNs) and without effective therapy. Drug screening is hampered by the lack of satisfactory experimental and pre-clinical models. Induced pluripotent stem cells (iPSCs) could help to define disease mechanisms and therapeutic strategies as they could be differentiated into MNs, otherwise inaccessible from living humans. In this study, given the seminal role of TDP-43 in ALS pathophysiology, MNs were obtained from peripheral blood mononuclear cells-derived iPSCs of an ALS patient carrying a p.A382T TARDBP mutation and a healthy donor. Venous samples were preferred to fibroblasts for their ease of collection and no requirement for time consuming extended cultures before experimentation. iPSCs were characterized for expression of specific markers, spontaneously differentiated into primary germ layers and, finally, into MNs. No differences were observed between the mutated ALS patient and the control MNs with most of the cells displaying a nuclear localization of the TDP-43 protein. In conclusion, we here demonstrated for the first time that human TARDBP mutated MNs can be successfully obtained exploiting the reprogramming and differentiation ability of peripheral blood cells, an easily accessible source from any patient
A model for the atomic-scale structure of a dense, nonequilibrium fluid: the homogeneous cooling state of granular fluids
It is shown that the equilibrium Generalized Mean Spherical Model of fluid
structure may be extended to nonequilibrium states with equation of state
information used in equilibrium replaced by an exact condition on the two-body
distribution function. The model is applied to the homogeneous cooling state of
granular fluids and upon comparison to molecular dynamics simulations is found
to provide an accurate picture of the pair distribution function.Comment: 29 pages, 11 figures Revision corrects formatting of the figure
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