Road salt emissions: A comparison of measurements and modelling using the NORTRIP road dust emission model

AbstractDe-icing of road surfaces is necessary in many countries during winter to improve vehicle traction. Large amounts of salt, most often sodium chloride, are applied every year. Most of this salt is removed through drainage or traffic spray processes but a certain amount may be suspended, after drying of the road surface, into the air and will contribute to the concentration of particulate matter. Though some measurements of salt concentrations are available near roads, the link between road maintenance salting activities and observed concentrations of salt in ambient air is yet to be quantified. In this study the NORTRIP road dust emission model, which estimates the emissions of both dust and salt from the road surface, is applied at five sites in four Nordic countries for ten separate winter periods where daily mean ambient air measurements of salt concentrations are available. The model is capable of reproducing many of the salt emission episodes, both in time and intensity, but also fails on other occasions. The observed mean concentration of salt in PM10, over all ten datasets, is 4.2 μg/m3 and the modelled mean is 2.8 μg/m3, giving a fractional bias of −0.38. The RMSE of the mean concentrations, over all 10 datasets, is 2.9 μg/m3 with an average R2 of 0.28. The mean concentration of salt is similar to the mean exhaust contribution during the winter periods of 2.6 μg/m3. The contribution of salt to the kerbside winter mean PM10 concentration is estimated to increase by 4.1 ± 3.4 μg/m3 for every kg/m2 of salt applied on the road surface during the winter season. Additional sensitivity studies showed that the accurate logging of salt applications is a prerequisite for predicting salt emissions, as well as good quality data on precipitation. It also highlights the need for more simultaneous measurements of salt loading together with ambient air concentrations to help improve model parameterisations of salt and moisture removal processes

EVerT: Cryotherapy versus salicylic acid for the treatment of verrucae - a randomised controlled trial

OBJECTIVE: To compare the clinical effectiveness and cost-effectiveness of cryotherapy using liquid nitrogen versus patient daily self-treatment with 50% salicylic acid for the treatment of verrucae (plantar warts). DESIGN: A multicentre, pragmatic, open, two-armed randomised controlled trial with an economic evaluation. Randomisation was simple, with the allocation sequence generated by a computer in a 1 : 1 ratio. SETTING: Podiatry clinics, university podiatry schools and primary care in England, Scotland and Ireland. PARTICIPANTS: Patients were eligible if they presented with a verruca which, in the opinion of the health-care professional, was suitable for treatment with both salicylic acid and cryotherapy, and were aged 12 years and over. INTERVENTIONS: Cryotherapy using liquid nitrogen delivered by a health-care professional compared with daily patient self-treatment with 50% salicylic acid (Verrugon, William Ransom & Son Plc, Hitchin, UK) for a maximum of 8 weeks. MAIN OUTCOME MEASURES: The primary outcome was complete clearance of all verrucae at 12 weeks. Secondary outcomes were complete clearance of all verrucae at 12 weeks, controlling for age, whether or not the verrucae had been previously treated and type of verrucae, with a second model to explore the effect of patient preferences, time to clearance of verrucae, clearance of verrucae at 6 months, number of verrucae at 12 weeks and patient satisfaction with the treatment RESULTS: In total, 240 eligible patients were recruited, with 117 patients allocated to the cryotherapy group and 123 to the salicylic acid group. There was no evidence of a difference in clearance rates between the treatment groups in the primary outcome [17/119 (14.3%) in the salicylic acid group vs 15/110 (13.6%) in the cryotherapy group; p = 0.89]. The results of the study did not change when controlled for age, whether or not the verrucae had been previously treated and type of verrucae, or when patient preferences were explored. There was no evidence of a difference in time to clearance of verrucae between the two groups [hazard ratio (HR) 0.80, 95% confidence interval (CI) 0.51 to 1.25; p = 0.33] or in the clearance of verrucae at 6 months (33.7% cryotherapy vs 30.5% salicylic acid). There was no evidence of a difference in the number of verrucae at 12 weeks between the two groups (incidence rate ratio 1.08, 95% CI 0.81 to 1.43; p = 0.62). Nineteen participants reported 28 adverse events, 14 in each group, with two treatment-related non-serious adverse events in the cryotherapy group. Cryotherapy was also associated with higher mean costs per additional healed patient (£101.17, 95% bias-corrected and accelerated CI £85.09 to £117.26). The probability of cryotherapy being cost-effective is 40% for a range of willingness-to-pay thresholds of £15,000-30,000 per patient healed. CONCLUSIONS: There is no evidence for a difference in terms of clearance of verrucae between cryotherapy and salicylic acid (at both 12 weeks and 6 months), number of verrucae at 12 weeks and time to clearance of verrucae. Cryotherapy was associated with higher mean costs per additional healed patient compared with salicylic acid. TRIAL REGISTRATION:Current Controlled Trials ISRCTN18994246. FUNDING: This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 15, No. 32. See the HTA programme website for further project information

Systematics of Heavy Quark Production at HERA

We discuss heavy quark and quarkonium production in various kinematic regions at the HERA ep collider. In contrast to fixed target experiments, collider kinematics allows the possibility of detailed measurements of particle production in the proton fragmentation region. One thus can study parton correlations in the proton Fock states materialized by the virtual photon probe. We discuss various configurations of inelastic electron-proton scattering, including peripheral, diffractive, and deep inelastic processes. In particular, we show that intrinsic heavy quark Fock states can be identified by the observation of quarkonium production at large $x_F$ and a low mean transverse momentum which is insensitive to the virtuality $Q^2$ of the photon.Comment: 17 pages, postscript. To obtain a copy of this paper send e-mail to [email protected]

A Unified Model of Exclusive ρ0\rho^0, ϕ\phi and \jpsi Electroproduction

A two-component model is developed for diffractive electroproduction of $\rho^0$, $\phi$ and \jpsi, based on non-perturbative and perturbative two-gluon exchange. This provides a common kinematical structure for non-perturbative and perturbative effects, and allows the role of the vector-meson vertex functions to be explored independently of the production dynamics. A good global description of the vector-meson data is obtained.Comment: 30 pages, 35 figure

The European Photon Imaging Camera on XMM-Newton: The MOS Cameras

The EPIC focal plane imaging spectrometers on XMM-Newton use CCDs to record the images and spectra of celestial X-ray sources focused by the three X-ray mirrors. There is one camera at the focus of each mirror; two of the cameras contain seven MOS CCDs, while the third uses twelve PN CCDs, defining a circular field of view of 30 arcmin diameter in each case. The CCDs were specially developed for EPIC, and combine high quality imaging with spectral resolution close to the Fano limit. A filter wheel carrying three kinds of X-ray transparent light blocking filter, a fully closed, and a fully open position, is fitted to each EPIC instrument. The CCDs are cooled passively and are under full closed loop thermal control. A radio-active source is fitted for internal calibration. Data are processed on-board to save telemetry by removing cosmic ray tracks, and generating X-ray event files; a variety of different instrument modes are available to increase the dynamic range of the instrument and to enable fast timing. The instruments were calibrated using laboratory X-ray beams, and synchrotron generated monochromatic X-ray beams before launch; in-orbit calibration makes use of a variety of celestial X-ray targets. The current calibration is better than 10% over the entire energy range of 0.2 to 10 keV. All three instruments survived launch and are performing nominally in orbit. In particular full field-of-view coverage is available, all electronic modes work, and the energy resolution is close to pre-launch values. Radiation damage is well within pre-launch predictions and does not yet impact on the energy resolution. The scientific results from EPIC amply fulfil pre-launch expectations.Comment: 9 pages, 11 figures, accepted for publication in the A&A Special Issue on XMM-Newto

Preferential regulation of stably expressed genes in the human genome suggests a widespread expression buffering role of microRNAs

In this study, we comprehensively explored the stably expressed genes (SE genes) and fluctuant genes (FL genes) in the human genome by a meta-analysis of large scale microarray data. We found that these genes have distinct function distributions. miRNA targets are shown to be significantly enriched in SE genes by using propensity analysis of miRNA regulation, supporting the hypothesis that miRNAs can buffer whole genome expression fluctuation. The expression-buffering effect of miRNA is independent of the target site number within the 3'-untranslated region. In addition, we found that gene expression fluctuation is positively correlated with the number of transcription factor binding sites in the promoter region, which suggests that coordination between transcription factors and miRNAs leads to balanced responses to external perturbations

The XMM-Newton Serendipitous Source Catalogue

We describe the production, properties and scientific potential of the XMM-Newton catalogue of serendipitous X-ray sources. The first version of this catalogue is nearing completion and is planned to be released before the end of 2002.Comment: Proceedings of the "X-ray surveys, in the light of the new observatories" workshop, Astronomische Nachrichten, in the press (4 pages, 3 eps figures, uses an.cls

Addressing the threat of climate change to agriculture requires improving crop resilience to short-term abiotic stress

Climate change represents a serious threat to global agriculture, necessitating the development of more environmentally resilient crops to safeguard the future of food production. The effects of climate change are appearing to include a higher frequency of extreme weather events and increased day-to-day weather variability. As such, crops which are able to cope with short-term environmental stress, in addition to those that are tolerant to longer term stress conditions are required . It is becoming apparent that the hitherto relatively little studied process of post-stress plant recovery could be key to optimizing growth and production under fluctuating conditions with intermittent transient stress events. Developing more durable crops requires the provision of genetic resources to identify useful traits through the development of screening protocols. Such traits can then become the objective of crop breeding programmes. In this study, we discuss these issues and outline example research in leafy vegetables that is investigating resilience to short-term abiotic stress