995 research outputs found
Fast beam stacking using RF barriers
Two barrier RF systems were fabricated, tested and installed in the Fermilab
Main Injector. Each can provide 8 kV rectangular pulses (the RF barriers) at 90
kHz. When a stationary barrier is combined with a moving barrier, injected
beams from the Booster can be continuously deflected, folded and stacked in the
Main Injector, which leads to doubling of the beam intensity. This paper gives
a report on the beam experiment using this novel technology.Comment: 2007 Particle Accelerator Conference (PAC07
Use of ERTS-1 data in the educational and applied research programs of agricultural extension
There are no author-identified significant results in this report
Use of ERTS-1 data in identification, classification, and mapping of salt-affected soils in California
There are no author-identified significant results in this report
A Central Partition of Molecular Conformational Space. IV. Extracting information from the graph of cells
In previous works [physics/0204035, physics/0404052, physics/0509126] a
procedure was described for dividing the -dimensional
conformational space of a molecular system into a number of discrete cells,
this partition allowed the building of a combinatorial structure from data
sampled in molecular dynamics trajectories: the graph of cells, that encodes
the set of cells in conformational space that are visited by the system in its
thermal wandering. Here we outline a set of procedures for extracting useful
information from this structure: 1st) interesting regions in the volume
occupied by the system in conformational space can be bounded by a polyhedral
cone whose faces are determined empirically from a set of relations between the
coordinates of the molecule, 2nd) it is also shown that this cone can be
decomposed into a hierarchical set of smaller cones, 3rd) the set of cells in a
cone can be encoded by a simple combinatorial sequence.Comment: added an intrduction and reference
Rigidity analysis of HIV-1 protease
We present a rigidity analysis on a large number of X-ray crystal structures
of the enzyme HIV-1 protease using the 'pebble game' algorithm of the software
FIRST. We find that although the rigidity profile remains similar across a
comprehensive set of high resolution structures, the profile changes
significantly in the presence of an inhibitor. Our study shows that the action
of the inhibitors is to restrict the flexibility of the beta-hairpin flaps
which allow access to the active site. The results are discussed in the context
of full molecular dynamics simulations as well as data from NMR experiments.Comment: 4 pages, 3 figures. Conference proceedings for CMMP conference 2010
which was held at the University of Warwic
Studies of Mass and Size Effects in Three-Dimensional Vibrofluidized Granular Mixtures
We examine the steady state properties of binary systems of driven inelastic
hard spheres. The spheres, which move under the influence of gravity, are
contained in a vertical cylinder with a vibrating base. We computed the
trajectories of the spheres using an event-driven molecular dynamics algorithm.
In the first part of the study, we chose simulation parameters that match those
of experiments performed by Wildman and Parker. Various properties computed
from the simulation including the density profile, granular temperature and
circulation pattern are in good qualitative agreement with the experiments. We
then studied the effect of varying the mass ratio and the size ratio
independently while holding the other parameters constant. The mass and size
ratio are shown to affect the distribution of the energy. The changes in the
energy distributions affect the packing fraction and temperature of each
component. The temperature of the heavier component has a non-linear dependence
on the mass of the lighter component, while the temperature of the lighter
component is approximately proportional to its mass. The temperature of both
components is inversely dependent on the size of the smaller component.Comment: 14 Pages, 12 Figures, RevTeX
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
An integrated study of earth resources in the State of California based on ERTS-1 and supporting aircraft data
There are no author-identified significant results in this report
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A 3D printed drug delivery implant formed from a dynamic supramolecular polyurethane formulation
Using a novel molecular design approach, we have prepared a thermo-responsive supramolecular polyurethane as a matrix material for use in drug eluting implants. The dynamic supramolecular polyurethane (SPU) is able to self-assemble through hydrogen bonding and π-π stacking interactions, resulting in an addressable polymer network with a relatively low processing temperature. The mechanical properties of the SPU demonstrated the material was self-supporting, stiff, yet flexible thus making it suitable for hot-melt extrusion processing, inclusive of related 3D printing approaches. Cell-based toxicity assays revealed the SPU to be non-toxic and therefore a viable candidate as a biocompatible polymer for implant applications. To this end, the SPU was formulated with paracetamol (16 %w/w) and 4 wt% or 8 wt% poly(ethylene glycol) (PEG) as an excipient and hot melt extruded at 100 °C to afford a 3D printed prototype implant to explore the extended drug release required for an implant and the potential manipulation of the release profile. Furthermore, rheological, infra-red spectroscopy, powder X-ray diffraction and scanning electron microscopy studies revealed the chemical and physical properties and compatibility of the formulation components. Successful release of paracetamol was achieved from in vitro dissolution studies and it was predicted that the drug would be released over a period of up to 8.5 months with hydrophilic PEG being able to influence the release rate. This extended release time is consistent with applications of this novel dynamic polymer as a drug eluting implant matrix
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