2,046 research outputs found
Monopolistic Competition with Two-Part Tariffs
Non-uniform pricing equilibria are shown to dominate uniform pricing
equilibria in free entry, monopolistically competitive markets with
identical consumers. The non-uniform pricing equilibrium is welfare
optimal. Comparisons of Cournot and non-uniform pricing equilibria in
terms of the equilibrium number of firms and sales per firm show that
the positioning of Cournot equilibria relative to the welfare optimal
configuration of firms and outputs depends on the relative curvatures of
inverse demand and average cost functions, entry-induced rotation of
inverse demand functions, and the relative price effects of changes in
own and other firms outputs. The choice between the non-uniform and
uniform pricing interpretations of equilibria in differentiated product
markets may have important implications for policy analysis
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
Looking Backwards and Looking Forwards in Contemplating the Next Rewrite of the Communications Act
Looking Backwards and Looking Forwards in Contemplating the Next Rewrite of the Communications Act
Variable temperature study of the crystal and magnetic structures of the giant magnetoresistant materials LMnAsO (L=La, Nd)
Peer reviewedPublisher PD
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
Addressing the inverse care law: how can we increase GP recruitment in areas of socioeconomic deprivation? A qualitative study of GP trainee views and experiences in the UK
Urinary ATP and visualization of intracellular bacteria: a superior diagnostic marker for recurrent UTI in renal transplant recipients?
Renal transplant recipients (RTR) are highly susceptible to urinary tract infections (UTIs) with over 50% of patients having at least one UTI within the first year. Yet it is generally acknowledged that there is considerable insensitivity and inaccuracy in routine urinalysis when screening for UTIs. Thus a large number of transplant patients with genuine urine infections may go undiagnosed and develop chronic recalcitrant infections, which can be associated with graft loss and morbidity. Given a recent study demonstrating ATP is released by urothelial cells in response to bacteria exposure, possibly acting at metabotropic P2Y receptors mediating a proinflammatory response, we have investigated alternative, and possibly more appropriate, urinalysis techniques in a cohort of RTRs.Mid-stream urine (MSU) samples were collected from 53 outpatient RTRs. Conventional leukocyte esterase and nitrite dipstick tests, and microscopic pyuria counts (in 1 ?l), ATP concentration measurements, and identification of intracellular bacteria in shed urothelial cells, were performed on fresh unspun samples and compared to âgold-standardâ bacterial culture results.Of the 53 RTRs, 22% were deemed to have a UTI by âgold-standardâ conventional bacteria culture, whereas 87%, 8% and 4% showed evidence of UTIs according to leukocyte esterase dipstick, nitrite dipstick, and a combination of both dipsticks, respectively. Intracellular bacteria were visualized in shed urothelial cells of 44% of RTRs, however only 1 of the 23 RTRs (44%) was deemed to have a UTI by conventional bacteria culture. A significant association of the âgold-standardâ test with urinary ATP concentration combined with visualization of intracellular bacteria in shed urothelial cells was determined using the Fisherâs exact test.It is apparent that standard bedside tests for UTIs give variable results and that seemingly quiescent bacteria in urothelial cells are very common in RTRs and may represent a focus of subclinical infection. Furthermore, our results suggest urinary ATP concentration combined with detection of intracellular bacteria in shed urinary epithelial cells may be a sensitive means by which to detect âoccultâ infection in RTRs
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Inserting Components into Geometries Constructed onto a Non-Standard Substrate for Electronics Packaging
Additive manufacturing (AM) has matured from its initial concept as a prototyping technique to an
industrial manufacturing process. Consequently, AM processes must meet relevant standards for
an increasing number of applications. Here, we investigate inserting components into geometries
constructed onto a silicon nitride substrate, using stereolithography (SLA), for the purpose of
electronics packaging. Compared to conventional processes, SLA avoids high temperatures and
stresses while permitting much greater flexibility to arrange components in three dimensions. This
facilitates an increased feature density and the construction of packages for use in complex spaces.
A characteristic of interest to this application, is the SLA material-substrate interaction and the
resulting quality of adhesion. The adhesion mechanism between SLA and silicon nitride is
investigated and substantially enhanced by a pre-treatment process. A process for then inserting
large and complex geometries and components into the SLA build process is identified and
compliance of the product with relevant standards is reviewed.Mechanical Engineerin
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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 Ï-Ï 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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