Relationships between synoptic-scale transport and interannual variability of inorganic cations in surface snow at Summit, Greenland: 1992-1996

Version of RecordTo fully utilize the long-term chemical records retrieved from central Greenland ice cores, specific relationships between atmospheric circulation and the variability of chemical species in the records need to be better understood. This research examines associations between the variability of surface snow inorganic cation chemistry at Summit, Greenland (collected during 1992-1996 summer field seasons) and changes in air mass transport pathways and source regions, as well as variations in aerosol source strength. Transport patterns and source regions are determined through 10-day isentropic backward air mass trajectories during a 1 month (late May to late June) common season over the 5 years. Changes in the extent of exposed continental surfaces in source regions are evaluated to estimate aerosol-associated calcium and magnesium ion source strength, while forest fire activity in the circumpolar north is investigated to estimate aerosol ammonium ion source strength. During the 1995 common season, 3 times more calcium and magnesium accumulated in the snowpack than the other study years. Also, an increasing trend of ammonium concentration was noted throughout the 5 years. Anomalous transport pathways and velocities were observed during 1995, which likely contributed to the high levels of calcium and magnesium. Increased forest fire activity in North America was concurrent with increased levels of ammonium and potassium, except for 1996, when ion levels were above average and forest fire activity was below average. Because of the ubiquitous nature of soluble ions, we conclude that it is very difficult to establish a quantitative link between the ion content of snow and firn at Summit and changes in aerosol source regions and source strength.Slater, J. F., Dibb, J. E., Keim, B. D., & Kahl, J. D. w. (2001). Relationships between synoptic-scale transport and interannual variability of inorganic cations in surface snow at Summit, Greenland: 1992-1996. Journal of Geophysical Research 106(D18), 20,897-20,91

Ultrasonography in the detection of fetal abnormalities in early pregnancy

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In-depth study of ‘decoupling point’ as a reference model: an application for health service supply chain

This paper reports the findings from a case study research about in-depth analysis of ‘decoupling point’ as a reference model to address a particular management dilemma. Managers from a health service organisation contacted the researchers to investigate possible causes of a managerial dilemma where managers and clinical professionals were not able to agree on a satisfactory decision. Researchers designed a decoupling point reference model where decision-making was taking place to decide which particular process would be chosen for treatment. Clinical professionals were favouring a particular process because of health benefits to patients, whereas managers were more inclined to support a different process, which seemed to bring better outcomes for the organisation. The decoupling point implied applying a hybrid strategy where lean and agile paradigms coexisted so that particular operational views of these different groups of professionals could be taken into account simultaneously. The current performance management system indicated some limitations in the sense that it did not include relevant knowledge of the processes that the reference model suggested. The paper concluded that reference models have potential to offer benefits if considered as tools of process-driven analysis for service organisations. They could serve to find out about potential conflict between different professional groups, as well as indicating the limitations or weaknesses of other critical aspects of management such as measuring of performance and allocations of resources so that better integration across all facets of the service could be achieved

Protected carotid-artery stenting versus endarterectomy in high-risk patients

BACKGROUND: Carotid endarterectomy is more effective than medical management in the prevention of stroke in patients with severe symptomatic or asymptomatic atherosclerotic carotid-artery stenosis. Stenting with the use of an emboli-protection device is a less invasive revascularization strategy than endarterectomy in carotid-artery disease. METHODS: We conducted a randomized trial comparing carotid-artery stenting with the use of an emboli-protection device to endarterectomy in 334 patients with coexisting conditions that potentially increased the risk posed by endarterectomy and who had either a symptomatic carotid-artery stenosis of at least 50 percent of the luminal diameter or an asymptomatic stenosis of at least 80 percent. The primary end point of the study was the cumulative incidence of a major cardiovascular event at 1 year--a composite of death, stroke, or myocardial infarction within 30 days after the intervention or death or ipsilateral stroke between 31 days and 1 year. The study was designed to test the hypothesis that the less invasive strategy, stenting, was not inferior to endarterectomy. RESULTS: The primary end point occurred in 20 patients randomly assigned to undergo carotid-artery stenting with an emboli-protection device (cumulative incidence, 12.2 percent) and in 32 patients randomly assigned to undergo endarterectomy (cumulative incidence, 20.1 percent; absolute difference, -7.9 percentage points; 95 percent confidence interval, -16.4 to 0.7 percentage points; P=0.004 for noninferiority, and P=0.053 for superiority). At one year, carotid revascularization was repeated in fewer patients who had received stents than in those who had undergone endarterectomy (cumulative incidence, 0.6 percent vs. 4.3 percent; P=0.04). CONCLUSIONS: Among patients with severe carotid-artery stenosis and coexisting conditions, carotid stenting with the use of an emboli-protection device is not inferior to carotid endarterectomy