1,606 research outputs found
Brownian Dynamics of a Sphere Between Parallel Walls
We describe direct imaging measurements of a colloidal sphere's diffusion
between two parallel surfaces. The dynamics of this deceptively simple
hydrodynamically coupled system have proved difficult to analyze. Comparison
with approximate formulations of a confined sphere's hydrodynamic mobility
reveals good agreement with both a leading-order superposition approximation as
well as a more general all-images stokeslet analysis.Comment: 4 pages, 3 figures, REVTeX with PostScript figure
PRICE DISCOVERY MECHANISMS AND ALTERNATIVES FOR CANADIAN AGRICULTURE; Part I: A Review of Pricing Mechanisms in Agriculture
The purpose of this section is to review pricing mechanisms in agriculture and food. We started by constructing a taxonomy and system of classification for pricing mechanisms that is rooted in economic theory. This framework was applied to 26 pricing mechanisms observed from the following product categories: · Beef · Hogs · Grains and oilseeds · Dairy · Poultry and Eggs · Processed Food and HorticultureDemand and Price Analysis,
Anomalous interactions in confined charge-stabilized colloid
Charge-stabilized colloidal spheres dispersed in weak 1:1 electrolytes are
supposed to repel each other. Consequently, experimental evidence for anomalous
long-ranged like-charged attractions induced by geometric confinement inspired
a burst of activity. This has largely subsided because of nagging doubts
regarding the experiments' reliability and interpretation. We describe a new
class of thermodynamically self-consistent colloidal interaction measurements
that confirm the appearance of pairwise attractions among colloidal spheres
confined by one or two bounding walls. In addition to supporting previous
claims for this as-yet unexplained effect, these measurements also cast new
light on its mechanism.Comment: 8 pages, 5 figures, RevTeX4. Conference proceedings for CODEF-04,
Colloidal Dispersions in External Fields, March 29 - April 1, 200
Drag reduction obtained by modifying a standard truck
A standard two-axle truck with a box-shaped cargo compartment was tested to determine whether significant reductions in aerodynamic drag could be obtained by modifying the front of the cargo compartment. The coastdown method was used to determine the total drag of the baseline vehicle, which had a square-cornered cargo box, and of several modified configurations. Test velocities ranged from 56.3 to 94.6 kilometers per hour (35 to 60 miles per hour). At 88.5 kilometers per hour (55 miles per hour), the aerodynamic drag reductions obtained with the modified configurations ranged from 8 to 30 percent
Guidance, Flight Mechanics and Trajectory Optimization. Volume 5 - State Determination And/or Estimation
Guidance, flight mechanics, and trajectory optimizatio
Weak Long-Ranged Casimir Attraction in Colloidal Crystals
We investigate the influence of geometric confinement on the free energy of
an idealized model for charge-stabilized colloidal suspensions. The mean-field
Poisson-Boltzmann formulation for this system predicts pure repulsion among
macroionic colloidal spheres. Fluctuations in the simple ions' distribution
provide a mechanism for the macroions to attract each other at large
separations. Although this Casimir interaction is long-ranged, it is too weak
to influence colloidal crystals' dynamics.Comment: 5 pages 2 figures ReVTe
Multi-Discipline Modeling of Complete Hypersonic Vehicles Using CFD Surrogates
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143103/1/6.2017-0182.pd
Correlated particle dynamics in concentrated quasi-two-dimensional suspensions
We investigate theoretically and experimentally how the hydrodynamically
correlated lateral motion of particles in a suspension confined between two
surfaces is affected by the suspension concentration. Despite the long range of
the correlations (decaying as 1/r^2 with the inter-particle distance r), the
concentration effect is present only at short inter-particle distances for
which the static pair correlation is nonuniform. This is in sharp contrast with
the effect of hydrodynamic screening present in unconfined suspensions, where
increasing the concentration changes the prefactor of the large-distance
correlation.Comment: 13 page
Aluminum sulfate significantly reduces the skin test response to common allergens in sensitized patients
BACKGROUND: Avoidance of allergens is still recommended as the first and best way to prevent allergic illnesses and their comorbid diseases. Despite a variety of attempts there has been very limited success in the area of environmental control of allergic disease. Our objective was to identify a non-invasive, non-pharmacological method to reduce indoor allergen loads in atopic persons' homes and public environments. We employed a novel in vivo approach to examine the possibility of using aluminum sulfate to control environmental allergens. METHODS: Fifty skin test reactive patients were simultaneously skin tested with conventional test materials and the actions of the protein/glycoprotein modifier, aluminum sulfate. Common allergens, dog, cat, dust mite, Alternaria, and cockroach were used in the study. RESULTS: Skin test reactivity was significantly reduced by the modifier aluminum sulfate. Our studies demonstrate that the effects of histamine were not affected by the presence of aluminum sulfate. In fact, skin test reactivity was reduced independent of whether aluminum sulfate was present in the allergen test material or removed prior to testing, indicating that the allergens had in some way been inactivated. CONCLUSION: Aluminum sulfate was found to reduce the in vivo allergic reaction cascade induced by skin testing with common allergens. The exact mechanism is not clear but appears to involve the alteration of IgE-binding epitopes on the allergen. Our results indicate that it may be possible to diminish the allergenicity of an environment by application of the active agent aluminum sulfate, thus producing environmental control without complete removal of the allergen
A numerical study of a binary Yukawa model in regimes characteristic of globular proteins in solutions
The main goal of this paper is to assess the limits of validity, in the
regime of low concentration and strong Coulomb coupling (high molecular
charges), for a simple perturbative approximation to the radial distribution
functions (RDF), based upon a low-density expansion of the potential of mean
force and proposed to describe protein-protein interactions in a recent
Small-Angle-Scattering (SAS) experimental study. A highly simplified Yukawa
(screened Coulomb) model of monomers and dimers of a charged globular protein
(-lactoglobulin) in solution is considered. We test the accuracy of the
RDF approximation, as a necessary complementary part of the previous
experimental investigation, by comparison with the fluid structure predicted by
approximate integral equations and exact Monte Carlo (MC) simulations. In the
MC calculations, an Ewald construction for Yukawa potentials has been used to
take into account the long-range part of the interactions in the weakly
screened cases. Our results confirm that the perturbative first-order
approximation is valid for this system even at strong Coulomb coupling,
provided that the screening is not too weak (i.e., for Debye length smaller
than monomer radius). A comparison of the MC results with integral equation
calculations shows that both the hypernetted-chain (HNC) and the Percus-Yevick
(PY) closures have a satisfactory behavior under these regimes, with the HNC
being superior throughout. The relevance of our findings for interpreting SAS
results is also discussed.Comment: Physical Review E, in press (2005
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