A polymer coated cicaprost-eluting stent increases neointima formation and impairs vessel function in the rabbit iliac artery

Drug-eluting stents have been successful in reducing in-stent restenosis but are not suitable for all lesion types and have been implicated in causing late stent thrombosis due to incomplete regeneration of the endothelial cell layer. In this study we implanted stents coated with cicaprost, a prostacyclin analogue with a long plasma half-life and antiproliferative effects on vascular smooth muscle cells, into the iliac arteries of rabbits. At 28-day follow-up we compared neointima formation within the stented vessels and vascular function in adjacent vessels, to assess if cicaprost could reduce restenosis without impairing vessel function. Arteries implanted with cicaprost eluting stents had significantly more neointima compared to bare metal stents. In adjacent segments of artery, endothelium-dependent relaxation was impaired by the cicaprost-eluting stent but vasodilation to an endothelium-independent vasodilator was maintained. We conclude that the presence of the polymer and sub-optimal release of cicaprost from the stent may be responsible for the increased neointma and impaired functional recovery of the endothelium observed. Further experiments should be aimed at optimising release of cicaprost and exploring different stent polymer coatings

The post-common-envelope, binary central star of the planetary nebula Hen 2-11

We present a detailed photometric study of the central star system of the planetary nebula Hen 2-11, selected for study because of its low-ionisation filaments and bipolar morphology - traits which have been strongly linked with central star binarity. Photometric monitoring with NTT-EFOSC2 reveals a highly irradiated, double-eclipsing, post-common-envelope system with a period of 0.609 d. Modelling of the lightcurve indicates that the nebular progenitor is extremely hot, while the secondary in the system is probably a K-type main sequence star. The chemical composition of the nebula is analysed, showing Hen 2-11 to be a medium-excitation non-Type I nebula. A simple photoionisation model is constructed determining abundance ratios of C/O and N/O which would be consistent with the common-envelope cutting short the AGB evolution of the nebular progenitor. The detection of a post-common-envelope binary system at the heart of Hen 2-11 further strengthens the link between binary progeny and the formation of axisymmetric planetary nebulae with patterns of low-ionisation filaments, clearly demonstrating their use as morphological indicators of central star binarity.Comment: Accepted for publication in A&A. 9 pages, 5 figures, 4 table

Spacing of Connections in Compression Flanges of Built-up Cold-formed Steel Beams

Built-up cold-formed steel sections may offer greater economy in building construction. Typical built-up sections are cellular decks or door and window header beams. A research project was initiated to determine if the current spacing criteria outlined in Section D1.2 of the AISI Specification accurately predicted the capacity of built-up sections with the cover plate in compression. This study showed that criteria No.2 of the AISI Design Specification spacing criteria is restrictive when applied to built-up cross sections in bending. All test sections continued to carry additional load after the cover plate buckled. The tests showed that as the spacing of connectors increased the moment capacity of the section decreased. An analytical procedure was developed to compute the nominal moment capacity for a range of connector spacings

Spacing of connections in compression elements for cold-formed steel members (beams)

PREFACE The spacing of connectors in compression elements of built-up flexural members was evaluated both experimentally and analytically at the University ofMissouri-Rolla (UMR) under the sponsorship of the American Iron and Steel Institute. A computational model was developed for determining the bending capacity of single-fluted sections with cover plates that do not have edge stiffeners. The results of the investigation are presented and recommendations are made for design of single-flute cross sections having cover plates without edge stiffeners. Previous research developments by Yener, at Purdue University, and Luttrell, at the University of West Virginia, were compared to the UMR experimental data, which consisted of 83 single flute built-up hat sections with and without edge stiffened cover plates. All hat sections were tested as simple span beams with cover plates in compression. The buckling behavior of edge stiffened cover plates and cover plates without edge stiffeners was investigated and discussed herein. The effective length factor and plate buckling coefficient were determined from the test results. A discussion of the correlation between the UMR experimental findings and the work of both Luttrell and Yener is presented. The UMR research validates the AISI Design Specification spacing criteria (Section D1.2) which restricts spacing to a value that will prevent any separation of the cover plate from the hat section between the connectors. This provision, however, is very conservative when applied to a section in bending because it yields very small connector spacings. The spacing of the connectors may be increased beyond that required by Section D1.2 which results in a reduction of strength. Tests have indicated that the capacity of the hat section is not diminished due to the onset of plate buckling in the cover plate. The hat section will continue to carry additional load because of the post-buckling strength provided by the cover plate. This report is based on a thesis submitted to the Faculty of the Graduate School of the University ofMissouri-Rolla in partial fulfillment of the requirements for the degree of Masters of Science in Civil Engineering. Technical guidance for this investigation was provided by the American Iron and Steel Institute\u27s Subcommittee on Flexural Members (J.N. Nunnery, Chairman) and Connections (M.Golovin, Chairman). The Subcommittees\u27 guidance is gratefully acknowledged. Thanks are also extended to H. H. Chen, D. F. Boring and S.P. Bridgewater, AISI staff, for their assistance

Electron transport properties of sub-3-nm diameter copper nanowires

Density functional theory and density functional tight-binding are applied to model electron transport in copper nanowires of approximately 1 nm and 3 nm diameters with varying crystal orientation and surface termination. The copper nanowires studied are found to be metallic irrespective of diameter, crystal orientation and/or surface termination. Electron transmission is highly dependent on crystal orientation and surface termination. Nanowires oriented along the [110] crystallographic axis consistently exhibit the highest electron transmission while surface oxidized nanowires show significantly reduced electron transmission compared to unterminated nanowires. Transmission per unit area is calculated in each case, for a given crystal orientation we find that this value decreases with diameter for unterminated nanowires but is largely unaffected by diameter in surface oxidized nanowires for the size regime considered. Transmission pathway plots show that transmission is larger at the surface of unterminated nanowires than inside the nanowire and that transmission at the nanowire surface is significantly reduced by surface oxidation. Finally, we present a simple model which explains the transport per unit area dependence on diameter based on transmission pathways results

Intra-dance variation among waggle runs and the design of efficient protocols for honey bee dance decoding

Noise is universal in information transfer. In animal communication, this presents a challenge not only for intended signal receivers, but also to biologists studying the system. In honey bees, a forager communicates to nestmates the location of an important resource via the waggle dance. This vibrational signal is composed of repeating units (waggle runs) that are then averaged by nestmates to derive a single vector. Manual dance decoding is a powerful tool for studying bee foraging ecology, although the process is time-consuming: a forager may repeat the waggle run 1- >100 times within a dance. It is impractical to decode all of these to obtain the vector; however, intra-dance waggle runs vary, so it is important to decode enough to obtain a good average. Here we examine the variation among waggle runs made by foraging bees to devise a method of dance decoding. The first and last waggle runs within a dance are significantly more variable than the middle run. There was no trend in variation for the middle waggle runs. We recommend that any four consecutive waggle runs, not including the first and last runs, may be decoded, and we show that this methodology is suitable by demonstrating the goodness-of-fit between the decoded vectors from our subsamples with the vectors from the entire dances

The planetary nebula IC 4776 and its post-common-envelope binary central star

We present a detailed analysis of IC 4776, a planetary nebula displaying a morphology believed to be typical of central star binarity. The nebula is shown to comprise a compact hourglass-shaped central region and a pair of precessing jet-like structures. Time-resolved spectroscopy of its central star reveals periodic radial velocity variability consistent with a binary system. While the data are insufficient to accurately determine the parameters of the binary, the most likely solutions indicate that the secondary is probably a low-mass main sequence star. An empirical analysis of the chemical abundances in IC 4776 indicates that the common-envelope phase may have cut short the AGB evolution of the progenitor. Abundances calculated from recombination lines are found to be discrepant by a factor of approximately two relative to those calculated using collisionally excited lines, suggesting a possible correlation between low abundance discrepancy factors and intermediate-period post-common-envelope central stars and/or Wolf-Rayet central stars. The detection of a radial velocity variability associated with binarity in the central star of IC 4776 may be indicative of a significant population of (intermediate-period) post-common-envelope binary central stars which would be undetected by classic photometric monitoring techniques.Comment: Accepted for publication in MNRA

Inefficiency as the major driver of excess costs in lung resection

BackgroundRisk-adjusted outcomes of surgical care are important for quality and cost assessments. Although cardiac surgery is commonly studied, risk-adjusted analysis of excess costs of lung resection has not been pursued.MethodsWe used 2002 to 2005 National Inpatient Sample of the Healthcare Cost and Utilization Project data to evaluate adverse outcomes and costs in elective lung resections in hospitals with more than 20 cases during that period. Adverse outcomes were inpatient death or excessive risk-adjusted postoperative stay. Logistic models were defined to predict adverse outcomes. Linear models were designed to predict costs. Hospital-specific adverse outcome rates and costs were measured to define performance outliers. Cost-effective reference hospitals were used to define total excess costs.ResultsAmong 12,182 patients at 215 hospitals undergoing lung resection, there were 336 inpatient deaths (2.8%) and 880 live discharges with prolonged risk-adjusted postoperative stay (7.2%). Predictive models for mortality and risk-adjusted postoperative stay had C statistics of 0.773 and 0.643, respectively. There were 11 ineffective hospitals (5.1%) with excessive adverse outcomes (P < .005) and 34 inefficient hospitals (15.8%) meeting quality measures but with higher than predicted costs (P < .0005). Ineffective hospitals had costs $1020 per case lower than predicted. Inefficient hospitals had costs$9978 higher than predicted.ConclusionsInefficiency is the major factor in excess inpatient costs associated with lung resection in this model. Although refinements in databases, including total physician costs and postdischarge adverse event costs, will alter models, excess costs of lung resection appear to be driven by inefficiency, not adverse outcomes