Doppler lidar observations of sensible heat flux and intercomparisons with a ground-based energy balance station and WRF model output

This is an open access article - Copyright @ 2009 E. Schweizerbart'sche VerlagsbuchhandlungDuring the Convective and Orographically induced Precipitation Study (COPS), a scanning Doppler lidar was deployed at Achern, Baden-Wüttemberg, Germany from 13th June to 16th August 2007. Vertical velocity profiles ('rays') through the boundary layer were measured every 3 seconds with vertical profiles of horizontal wind velocity being derived from performing azimuth scans every 30 minutes. During Intense Observation Periods radiosondes were launched from the site. In this paper, a case study of convective boundary layer development on 15th July 2007 is investigated. Estimates of eddy dissipation rate are made from the vertically pointing lidar data and used as one input to the velocity-temperature co-variance equation to estimate sensible heat flux. The sensible heat flux values calculated from Doppler lidar data are compared with a surface based energy balance station and output from the Weather Research and Forecasting (WRF) model.Funding is obtained from NER

Characterisation and Evaluation of Poly(2- Methacryloyl-oxy) Ethyl Phosphorylcholine - Poly(2-Diisopropyl-amino) Ethyl Methacrylate (PMPC-PDPA) Self-Assembly for Biomedical Applications

Drug Delivery Systems (DDS) can be used to improve the effectiveness of therapeutic small molecules by enabling specific targeting, lower doses and reduced side effects. Polymersomes are a fully synthetic, non-toxic DDS capable of entrapping, delivering and releasing a therapeutic cargo inside mammalian cells. Improvements to the production and purification processes for polymersomes may improve their efficiency as a DDS. The aim of this thesis was to investigate the formation of dispersed pH responsive PMPC-PDPA polymersomes specifically for drug delivery applications. Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), potentiometry and turbidity measurements were used to characterise polymersomes and their formation. The effects of sample temperature on the formation of polymersomes by pH increase was studied with the aim of controlling polymersome size. Four copolymers were used, each with identical PMPC block lengths and different PDPA block lengths. It was found that the smallest copolymer investigated(PMPC25-PDPA47) formed micelles, while the remaining three copolymers with varying lengths favoured the formation of polymersomes. Additionally, a shift in the copolymer acid dissociation constant was observed using potentiometry and a trend of smaller particles being formed at higher temperatures (30-50°C) and shorter PDPA block length (PDPA47-94) was also observed. Morphological analysis revealed the formation of polymersomes, micelles and complex structures known as genus particles. Across the four copolymers, micelles were generally formed at the higher temperatures (50°C), while genus structures were formed at low temperatures (<15°C) and polymersomes formed at intermediate temperatures (20-37°C).Genus particles were then studied further as there are only a handful of publications on experimentally observed genus particles formed from amphiphiles. It was observed via morphological analysis that both the number of genus events (holes) and the size of the particles increased with decreasing temperature. The theory that these structures were formed by the addition of 9 extra copolymer chains to the outside of already formed polymersomes was tested by mixing dissolved unimers with formed polymersomes at low temperatures. The resulting structures were not full genus particles but there were noticeable differences in the particle topologies compared to polymersome-only samples. The relationship between temperature and polymersome formation was also explored further by driving the formation via a temperature increase as opposed to a pH increase. This was conducted using a spectrophotometer with an inbuilt temperature control unit so that formation was measured in situ via an increase in sample turbidity. Formation through temperature change was achieved by maintaining sample pH and increasing the temperature, then TEM was used to confirm the formation of polymersomes. Finally, an improved calculation of encapsulation efficiency was produced by incorporating the measured size distribution data obtained from DLS into the estimation. An automated Size Exclusion Chromatography (SEC) system was also set up to compare the purification against currently used bench-top systems. Samples processed using the automated system and the improved calculation could be used to more accurately predict the encapsulation of a hydrophilic compound and as a point of reference for encapsulation experiments. This work demonstrates the high degree of flexibility associated with the formation process of PMPC-PDPA polymersomes and related structures for drug delivery applications. Future work would include further characterisation of genus particles, in vitro delivery studies and experimental validation of the encapsulation model

Quantifying the Topology of Large-Scale Structure

We propose and investigate a new algorithm for quantifying the topological properties of cosmological density fluctuations. We first motivate this algorithm by drawing a formal distinction between two definitions of relevant topological characteristics, based on concepts, on the one hand, from differential topology and, on the other, from integral geometry. The former approach leads one to concentrate on properties of the contour surfaces which, in turn, leads to the algorithms CONTOUR2D and CONTOUR3D familiar to cosmologists. The other approach, which we adopt here, actually leads to much simpler algorithms in both two and three dimensions. (The 2D algorithm has already been introduced to the astronomical literature.) We discuss the 3D case in some detail and compare results obtained with it to analogous results using the CONTOUR3D algorithm.Comment: 10 pages, LaTex using mn.sty, 3 figures available on request from [email protected]; MNRAS, in pres

Markers of risk in patients with acute coronary syndrome treated by percutaneous coronary intervention

Background - The clinical diagnosis and categorisation of Acute Coronary Syndrome (ACS) has changed repeatedly over the last decade as have routine treatment strategies. Hypothesis - that adverse clinical events following PCI, may be predicted from the identification of markers of risk at the time of PCI. Methods - Informed consent was obtained from 968 patients fulfilling detailed inclusion and exclusion criteria surrounding a diagnosis of ACS requiring PCI. Standard medical ACS care was provided. PCI operators, techniques, methods and any decision to treat followed usual practice. Data collection took place at the time of intervention and during active follow-up. Blood sample were collected at baseline and 4 and 12 hours after PCI, being processed and refrigerated. Platelet function was assessed at baseline using the VerifyNow test method. Results – Data collection was over a median follow-up time of 3.56 years. Patients were aged 27 to 90 years and a majority were male (75%). Angiographic complications occurred in 13.2% and total complications in 17.1%. A majority (844; 86%) had neither restenosis nor subsequent unplanned revascularization. Recurrent ACS was 6.7% for year 1 and 1.8% additionally for each year thereafter. Stent thrombosis was observed in 18 (1.8%) cases. Bleeding occurred in 9% across the entire follow-up period, being greatest in the first 12 months. Platelet reactivity was highly variable and optimal with regard to outcome in the range of 179 to 243 (Platelet Reactivity Units PRU). Cardiac biomarkers were commonly elevated after PCI but procedural MI was very rare. H-FABP at baseline was strongly predictive of outcome. Conclusion – Adverse clinical events following PCI, such as stent thrombosis, bleeding and in-stent restenosis, may be predicted from the identification of markers of risk at the time of PCI, particularly by the use of risk scores, platelet function testing and measuring biomarker levels

Modeling Ka-band low elevation angle propagation statistics

The statistical variability of the secondary atmospheric propagation effects on satellite communications cannot be ignored at frequencies of 20 GHz or higher, particularly if the propagation margin allocation is such that link availability falls below 99 percent. The secondary effects considered in this paper are gaseous absorption, cloud absorption, and tropospheric scintillation; rain attenuation is the primary effect. Techniques and example results are presented for estimation of the overall combined impact of the atmosphere on satellite communications reliability. Statistical methods are employed throughout and the most widely accepted models for the individual effects are used wherever possible. The degree of correlation between the effects is addressed and some bounds on the expected variability in the combined effects statistics are derived from the expected variability in correlation. Example estimates are presented of combined effects statistics in the Washington D.C. area of 20 GHz and 5 deg elevation angle. The statistics of water vapor are shown to be sufficient for estimation of the statistics of gaseous absorption at 20 GHz. A computer model based on monthly surface weather is described and tested. Significant improvement in prediction of absorption extremes is demonstrated with the use of path weather data instead of surface data

Are patients willing participants in the new wave of community-based medical education in regional and rural Australia?

Community-based medical education is escalating to meet the increased demand for quality clinical education in expanded settings and patient participation is vital to the sustainability of this endeavour. This study aimed to investigate patients’ views on being used as an educational resource in medical student teaching, and whether they are being under- or over-used

Quinone synthesis and a visual introduction to column chromatography : an undergraduate experiment

An introductory normal phase column chromatography experiment is described and evaluated for second year undergraduate chemistry laboratory class. The experiment involves a nucleophilic substitution yielding a crude mixture of reactant and one product, both of which are brightly colored and contrasting, creating a clearly visual separation when purified using column chromatography. A student survey was conducted which showed that 75.4% of students (n = 53, approximately 50% of year group) agreed or strongly agreed that the experiment worked well for them, and 88.7% agreed or strongly agreed that the experiment was enjoyable. Every student was also assessed in the lab on their practical technique, with the year group achieving an average of 72.1% in this assessment

Speleothem growth intervals reflect New Zealand montane vegetation response to temperature change over the last glacial cycle

Flowstone speleothem growth beneath Mount Arthur, New Zealand shows a clear relationship to vegetation density and soil development on the surface above. Flowstone does not currently form beneath sub-alpine Nothofagus forest above ca. 1000–1100 m altitude but U-Th dating shows it has formed there during past intervals of warmer-than-present conditions including an early–mid Holocene optimum and the last interglacial from ca. 131–119 ka. Some flowstones growing beneath ca. 600 m surface altitude, currently mantled with dense broadleaf-podocarp forest, grew during full glacial conditions, indicating that local tree line was never below this altitude. This implies that Last Glacial Maximum annual temperature was no more than ca. 4 °C cooler than today. Flowstone growth appears to be a robust indicator of dense surface vegetation and well-developed soil cover in this setting, and indicates that past interglacial climates of MIS 7e, 5e, the early–mid Holocene and possibly MIS 5a were more conducive to growth of trees than was the late Holocene, reflecting regional temperature changes similar in timing to Antarctic temperature changes. Here, flowstone speleothem growth is a sensitive indicator of vegetation density at high altitude, but may respond to other factors at lower altitudes