The 1962 and 1970 Huascarán mass movements, originated as rock/ice falls from the mountain's North Peak, transformed into higher-volume high-velocity mud-rich debris flows by incorporation of snow ...from the surface of a glacier below Huascarán and the substantial entrainment of morainic and colluvial material from slopes below the glacier terminus. Water for fluidization of the entrained material originated in the melting of incorporated snow and the liberation of soil moisture contained within the entrained materials. Eyewitness reports indicate very high mean velocities for the events; 17–35 m/s (1962) and 50–85 m/s (1970). The runout distances and velocity profiles of both events were simulated using DAN/W. Both mass movements continued downstream in the Rio Santa as debris floods (aluviones) that in 1970 reached the Pacific at a distance of 180 km. In strong contrast to publications in the geosciences literature, 1961 Peru Census data indicates that the death toll of the 1970 event is ca. 6000 and that total life loss in the two events did not exceed 7000 people.
Oceanic emissions of dimethyl sulfide (CH.sub.3 SCH.sub.3, DMS) have long been recognized to impact aerosol particle composition and size, the concentration of cloud condensation nuclei (CCN), and ...Earth's radiation balance. The impact of oceanic emissions of methanethiol (CH.sub.3 SH, MeSH), which is produced by the same oceanic precursor as DMS, on the volatile sulfur budget of the marine atmosphere is largely unconstrained. Here we present direct flux measurements of MeSH oceanic emissions using the eddy covariance (EC) method with a high-resolution proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToFMS) detector and compare them to simultaneous flux measurements of DMS emissions from a coastal ocean site. Campaign mean mixing ratios of DMS and MeSH were 72 ppt (28-90 ppt interquartile range) and 19.1 ppt (7.6-24.5 ppt interquartile range), respectively. Campaign mean emission fluxes of DMS (F.sub.DMS) and MeSH (F.sub.MeSH) were 1.13 ppt m s.sup.-1 (0.53-1.61 ppt m s.sup.-1 interquartile range) and 0.21 ppt m s.sup.-1 (0.10-0.31 ppt m s.sup.-1 interquartile range), respectively. Linear least squares regression of observed MeSH and DMS flux indicates the emissions are highly correlated with each other (R.sup.2 =0.65) over the course of the campaign, consistent with a shared oceanic source. The campaign mean DMS to MeSH flux ratio (F.sub.DMS :F.sub.MeSH) was 5.5 ± 3.0, calculated from the ratio of 304 individual coincident measurements of F.sub.DMS and F.sub.MeSH . Measured F.sub.DMS :F.sub.MeSH was weakly correlated (R.sup.2 =0.15) with ocean chlorophyll concentrations, with F.sub.DMS :F.sub.MeSH reaching a maximum of 10.8 ± 4.4 during a phytoplankton bloom period. No other volatile sulfur compounds were observed by PTR-ToFMS to have a resolvable emission flux above their flux limit of detection or to have a gas-phase mixing ratio consistently above their limit of detection during the study period, suggesting DMS and MeSH are the dominant volatile organic sulfur compounds emitted from the ocean at this site.
A large rock avalanche occurred at 03:27:30 PDT, 6 August 2010, in the Mount Meager Volcanic Complex southwest British Columbia. The landslide initiated as a rock slide in Pleistocene rhyodacitic ...volcanic rock with the collapse of the secondary peak of Mount Meager. The detached rock mass impacted the volcano's weathered and saturated flanks, creating a visible seismic signature on nearby seismographs. Undrained loading of the sloping flank caused the immediate and extremely rapid evacuation of the entire flank with a strong horizontal force, as the rock slide transformed into a debris flow. The disintegrating mass travelled down Capricorn Creek at an average velocity of 64 m s−1, exhibiting dramatic super-elevation in bends to the intersection of Meager Creek, 7.8 km from the source. At Meager Creek the debris impacted the south side of Meager valley, causing a runup of 270 m above the valley floor and the deflection of the landslide debris both upstream (for 3.7 km) and downstream into the Lillooet River valley (for 4.9 km), where it blocked the Lillooet River river for a couple of hours, approximately 10 km from the landslide source. Deposition at the Capricorn–Meager confluence also dammed Meager Creek for about 19 h creating a lake 1.5 km long. The overtopping of the dam and the predicted outburst flood was the basis for a night time evacuation of 1500 residents in the town of Pemberton, 65 km downstream. High-resolution GeoEye satellite imagery obtained on 16 October 2010 was used to create a post-event digital elevation model. Comparing pre- and post-event topography we estimate the volume of the initial displaced mass from the flank of Mount Meager to be 48.5 × 106 m3, the height of the path (H) to be 2183 m and the total length of the path (L) to be 12.7 km. This yields H/L = 0.172 and a fahrböschung (travel angle) of 9.75°. The movement was recorded on seismographs in British Columbia and Washington State with the initial impact, the debris flow travelling through bends in Capricorn Creek, and the impact with Meager Creek are all evident on a number of seismograms. The landslide had a seismic trace equivalent to a M = 2.6 earthquake. Velocities and dynamics of the movement were simulated using DAN-W. The 2010 event is the third major landslide in the Capricorn Creek watershed since 1998 and the fifth large-scale mass flow in the Meager Creek watershed since 1930. No lives were lost in the event, but despite its relatively remote location direct costs of the 2010 landslide are estimated to be in the order of $10 M CAD.
Abstract Background Providing supported self-management for people with asthma can reduce the burden on patients, health services and wider society. Implementation, however, remains poor in routine ...clinical practice. IMPlementing IMProved Asthma self-management as RouTine (IMP 2 ART) is a UK-wide cluster randomised implementation trial that aims to test the impact of a whole-systems implementation strategy, embedding supported asthma self-management in primary care compared with usual care. To maximise opportunities for sustainable implementation beyond the trial, it is necessary to understand how and why the IMP 2 ART trial achieved its clinical and implementation outcomes. Methods A mixed-methods process evaluation nested within the IMP 2 ART trial will be undertaken to understand how supported self-management was implemented (or not) by primary care practices, to aid interpretation of trial findings and to inform scaling up and sustainability. Data and analysis strategies have been informed by mid-range and programme-level theory. Quantitative data will be collected across all practices to describe practice context, IMP 2 ART delivery (including fidelity and adaption) and practice response. Case studies undertaken in three to six sites, supplemented by additional interviews with practice staff and stakeholders, will be undertaken to gain an in-depth understanding of the interaction of practice context, delivery, and response. Synthesis, informed by theory, will combine analyses of both qualitative and quantitative data. Finally, implications for the scale up of asthma self-management implementation strategies to other practices in the UK will be explored through workshops with stakeholders. Discussion This mixed-methods, theoretically informed, process evaluation seeks to provide insights into the delivery and response to a whole-systems approach to the implementation of supported self-management in asthma care in primary care. It is underway at a time of significant change in primary care in the UK. The methods have, therefore, been developed to be adaptable to this changing context and to capture the impact of these changes on the delivery and response to research and implementation processes.
Dry deposition of ozone (O3) to the ocean surface and the ozonolysis of organics in the sea surface microlayer (SSML) are potential sources of volatile organic compounds (VOCs) to the marine ...atmosphere. We use a gas chromatography system coupled to a Vocus proton-transfer-reaction time-of-flight mass spectrometer to determine the chemical composition and product yield of select VOCs formed from ozonolysis of coastal seawater collected from Scripps Pier in La Jolla, California. Laboratory-derived results are interpreted in the context of direct VOC vertical flux measurements made at Scripps Pier. The dominant products of laboratory ozonolysis experiments and the largest non-sulfur emission fluxes measured in the field correspond to Vocus CxHy+ and CxHyOz+ ions. Gas chromatography (GC) analysis suggests that C5–C11 oxygenated VOCs, primarily aldehydes, are the largest contributors to these ion signals. In the laboratory, using a flow reactor experiment, we determine a VOC yield of 0.43–0.62. In the field at Scripps Pier, we determine a maximum VOC yield of 0.04–0.06. Scaling the field and lab VOC yields for an average O3 deposition flux and an average VOC structure results in an emission source of 10.7 to 167 Tg C yr−1, competitive with the DMS source of approximately 20.3 Tg C yr−1. This study reveals that O3 reactivity to dissolved organic carbon can be a significant carbon source to the marine atmosphere and warrants further investigation into the speciated VOC composition from different seawater samples and the reactivities and secondary organic aerosol (SOA) yields of these molecules in marine-relevant, low NOx conditions.
Organic emissions from coastal waters play an important but poorly understood role in atmospheric chemistry in coastal regions. A mesocosm experiment focusing on facilitated biological blooms in ...coastal seawater, SeaSCAPE (Sea Spray Chemistry and Particle Evolution), was performed to study emission of volatile gases, primary sea spray aerosol, and formation of secondary marine aerosol as a function of ocean biological and chemical processes. Here, we report observations of aerosol-phase benzothiazoles in a marine atmospheric context with complementary measurements of dissolved-phase benzothiazoles. Though previously reported dissolved in polluted coastal waters, we report the first direct evidence of the transfer of these molecules from seawater into the atmosphere. We also report the first gas-phase observations of benzothiazole in the environment absent a direct industrial, urban, or rubber-based source. From the identities and temporal dynamics of the dissolved and aerosol species, we conclude that the presence of benzothiazoles in the coastal water (and thereby their emissions into the atmosphere) is primarily attributable to anthropogenic sources. Oxidation experiments to explore the atmospheric fate of gas-phase benzothiazole show that it produces secondary aerosol and gas-phase SO2, making it a potential contributor to secondary marine aerosol formation in coastal regions and a participant in atmospheric sulfur chemistry.
To evaluate the clinical effectiveness and cost-effectiveness of proton pump inhibitors (PPIs) in the prevention and treatment of acute upper gastrointestinal (UGI) haemorrhage, as well as to compare ...this with H2-receptor antagonist (H2RA), Helicobacter pylori eradication (in infected patients) or no therapy, for the prevention of first and/or subsequent bleeds among patients who continue to use non-steroidal anti-inflammatory drugs (NSAIDs). Also to evaluate the clinical effectiveness of PPI therapy, compared with other treatments, for the prevention of subsequent bleeds in patients who had previously experienced peptic ulcer (PU) bleeding.
Electronic databases and major conference proceedings were searched up to February 2006.
Data were collected from the systematic reviews addressing each research objective. These were then entered into an economic model to compare the costs and quality-adjusted life-days of alternative management strategies over a 28-day period for patients who have had UGI bleeding. A Markov model with a Monte Carlo simulation used data from the systematic reviews to identify the most cost-effective treatment strategy for the prevention of UGI bleeding (first and subsequent) among NSAID users using an outcome of costs per quality-adjusted life-years (QALYs) over a lifetime from age 50 years.
PPI treatment initiated after endoscopic diagnosis of PU bleeding significantly reduced re-bleeding and surgery compared with placebo or H2RA. Although there was no evidence of an overall effect of PPI treatment on all-cause mortality, PPIs significantly reduced mortality in subgroups when studies conducted in Asia were examined in isolation or when the analysis was confined to patients with high-risk endoscopic findings. PPI treatment initiated prior to endoscopy in UGI bleeding significantly reduced the proportion of patients with stigmata of recent haemorrhage (SRH) at index endoscopy compared with placebo or H2RA, but there was no evidence that PPI treatment affected clinically important outcomes. Giving oral PPI both before and after endoscopy, with endoscopic haemostatic therapy (EHT) for those with major SRH, is preferred to all others on cost-effectiveness grounds at any threshold over 25,000 pounds per QALY, even if only short-term effects are taken into account, and at any threshold over 200 pounds per life-year gained if long-term effects are included. The risk of NSAID-induced endoscopic gastric and duodenal ulcers was reduced by standard doses of PPI and misoprostol, and double doses of H2RAs. Standard doses of H2RAs reduced the risk of endoscopic duodenal ulcers. PPIs reduced NSAID-induced dyspepsia. PPIs were superior to misoprostol in preventing recurrence of NSAID-induced endoscopic duodenal ulcers, but PPIs were comparable to misoprostol in preventing the recurrence of NSAID-induced endoscopic gastric ulcers. Full-dose misoprostol reduced bleeding, perforation or gastric outlet obstruction due to NSAID-induced ulcers, but misoprostol was poorly tolerated and associated with frequent adverse effects. H. pylori eradication treatment was equally effective with PPI treatment for the primary or secondary prevention of endoscopic ulcers in NSAID users. H. pylori eradication treatment was more effective than placebo for the primary prevention of endoscopic PU and for the prevention of re-bleeding from PU in NSAID users. With regard to primary and secondary prevention of bleeding PU in NSAID users, the two most cost-effective strategies are H. pylori eradication alone, and H. pylori eradication followed by misoprostol (substituted by a PPI, if misoprostol is not tolerated) at an additional 4810 pounds per QALY. In patients who had previously experienced a bleed from a PU, re-bleeding was less frequent after H. pylori eradication therapy than after non-eradication antisecretory therapy, whether or not the latter was combined with long-term maintenance antisecretory therapy.
PPI treatment compared with placebo or H2RA reduces mortality following PU bleeding among patients with high-risk endoscopic findings, and reduces re-bleeding rates and surgical intervention. PPI treatment initiated prior to endoscopy in UGI bleeding significantly reduces the proportion of patients with SRH at index endoscopy but does not reduce mortality, re-bleeding or the need for surgery. The strategy of giving oral PPI before and after endoscopy, with EHT for those with major SRH, is likely to be the most cost-effective. Treatment of H. pylori infection was found to be more effective than antisecretory therapy in preventing recurrent bleeding from PU. H. pylori eradication alone or eradication followed by misoprostol (with switch to PPI, if misoprostol is not tolerated) are the two most cost-effective strategies for preventing bleeding ulcers among H. pylori-infected NSAID users, although the data cannot exclude PPIs also being cost-effective. Further large randomised controlled trials are needed to address areas such as PPI administration prior to endoscopic diagnosis, different doses and administration of PPIs, as well as the primary and secondary prevention of UGI bleeding.
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