4,475 research outputs found
Influence of Hydrodynamic Interactions on the Kinetics of Colloidal Particle's Adsorption
The kinetics of irreversible adsorption of spherical particles onto a flat
surface is theoretically studied. Previous models, in which hydrodynamic
interactions were disregarded, predicted a power-law behavior for
the time dependence of the coverage of the surface near saturation.
Experiments, however, are in agreement with a power-law behavior of the form
. We outline that, when hydrodynamic interactions are considered, the
assymptotic behavior is found to be compatible with the experimental results in
a wide region near saturation.Comment: 4 pages, 1 figures, Phys. Rev. Lett. (in press
Adsorption of colloidal particles in the presence of external field
We present a new class of sequential adsorption models in which the adsorbing
particles reach the surface following an inclined direction (shadow models).
Capillary electrophoresis, adsorption in the presence of a shear or on an
inclined substrate are physical manifestations of these models. Numerical
simulations are carried out to show how the new adsorption mechanisms are
responsible for the formation of more ordered adsorbed layers and have
important implications in the kinetics, in particular modifying the jamming
limit.Comment: LaTex file, 3 figures available upon request, to appear in
Phys.Rev.Let
Examining the neuroscience evidence for sensory-driven neuroplasticity: implications for sensory-based occupational therapy for children and adolescents.
When Ayres first presented the theory of sensory integration (SI), she grounded it in the neuroscience literature. Neuroplasticity was then, and is today, considered to be at the heart of this theory. This evidence-based review sought to critically examine the basic science literature to specifically identify evidence for the assumptions and tenets of Ayres\u27 theory of SI. We reviewed literature between 1964 and 2005, within psychological, physiological, and biomedical areas, addressing neuroplasticity. The review focused on sensorimotor-based neuroplasticity; explored the data that addressed the links among sensory input, brain function, and behavior; and evaluated its relevance in terms of supporting or refuting the theoretical premise of occupational therapy using an SI framework (OT/SI) to treatment. Although direct application from basic science to OT/SI is not feasible, we concluded that there was a basis for the assumptions of Ayes\u27 SI theory
Model of correlated sequential adsorption of colloidal particles
We present results of a new model of sequential adsorption in which the
adsorbing particles are correlated with the particles attached to the
substrate. The strength of the correlations is measured by a tunable parameter
. The model interpolates between free ballistic adsorption in the limit
and a strongly correlated phase, appearing for
and characterized by the emergence of highly ordered structures. The phenomenon
is manifested through the analysis of several magnitudes, as the jamming limit
and the particle-particle correlation function. The effect of correlations in
one dimension manifests in the increased tendency to particle chaining in the
substrate. In two dimensions the correlations induce a percolation transition,
in which a spanning cluster of connected particles appears at a certain
critical value . Our study could be applicable to more general
situations in which the coupling between correlations and disorder is relevant,
as for example, in the presence of strong interparticle interactions.Comment: 6 pages, 8 EPS figures. Phys. Rev. E (in press
Quantum Drag Forces on a Sphere Moving Through a Rarefied Gas
As an application of quantum fluid mechanics, we consider the drag force
exerted on a sphere by an ultra-dilute gas. Quantum mechanical diffraction
scattering theory enters in that regime wherein the mean free path of a
molecule in the gas is large compared with the sphere radius. The drag force is
computed in a model specified by the ``sticking fraction'' of events in which a
gaseous molecule is adsorbed by the spherical surface. Classical inelastic
scattering theory is shown to be inadequate for physically reasonable sticking
fraction values. The quantum mechanical scattering drag force is exhibited
theoretically and compared with experimental data.Comment: 5 pages no figure
Geography and art: encountering place across disciplines
This article summarises a project undertaken at the Newton Park campus of Bath Spa University over 1 week in October 2015. The project provided a space for interdisciplinary collaborations between geography and art students to explore the commonalities and differences in how they saw, interpreted and creatively re-presented the campus, using a variety of methods. This article outlines the project and reflects on the processes, outcomes, and challenges of collaboration. It highlights how this approach can enhance student learning experiences, by facilitating more interdisciplinary collaboration across the sciences, arts and humanities, and social sciences. In doing so, it explores the potential and pitfalls of collaborative cultural geography in practice across disciplines
Development and Evaluation of an Adaptive Digital Module on Enzyme Kinetics
An adaptive module on basic enzyme kinetics was developed for first- and second-year university students. The module offers more assignments to students who have less knowledge of the theory than to more advanced students. The aim of the research was to investigate what influence students’ backgrounds have on their use and appreciation of this module. Both freshmen and second-year students showed a large variation in the number of assignments they needed to perform in order to finish the module, indicating that the module’s adaptive feature was exploited by all the students. Findings indicated that the prior knowledge was of influence of students’ motivation and perception of difficulty of the modul
Astrophysical Supercomputing with GPUs: Critical Decisions for Early Adopters
General purpose computing on graphics processing units (GPGPU) is
dramatically changing the landscape of high performance computing in astronomy.
In this paper, we identify and investigate several key decision areas, with a
goal of simplyfing the early adoption of GPGPU in astronomy. We consider the
merits of OpenCL as an open standard in order to reduce risks associated with
coding in a native, vendor-specific programming environment, and present a GPU
programming philosophy based on using brute force solutions. We assert that
effective use of new GPU-based supercomputing facilities will require a change
in approach from astronomers. This will likely include improved programming
training, an increased need for software development best-practice through the
use of profiling and related optimisation tools, and a greater reliance on
third-party code libraries. As with any new technology, those willing to take
the risks, and make the investment of time and effort to become early adopters
of GPGPU in astronomy, stand to reap great benefits.Comment: 13 pages, 5 figures, accepted for publication in PAS
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