A Study on Onset of Liquid Entrainment in Low Pressure Depressurization System of Advanced Passive Pressurized Water Reactors

The low-pressure depressurization system (LPDS) of advanced passive pressurized water reactors (PWRs) is designed to provide depressurization of the reactor coolant system during a small break loss-of-coolant accident (LOCA). The liquid entrainment to the LPDS is important for the safety case of the advanced passive PWRs due to the significant increase of the pressure loss and the depressurization rate versus mass loss characteristics. The existing experimental researches on the liquid entrainment at LPDS have been reviewed, and the intermittent entrainment mechanism and the continuous entrainment mechanism are identified. The intermittent entrainment is closely related to the flow regime transition from the horizontal stratified flow to the intermittent flow in the hot leg where the LPDS port is located. The horizontal stratification model previously developed for the FULL SPECTRUM LOCA evaluation model has been assessed against the entrainment onset data in the available LPDS entrainment experiments, i.e., the ATLATS air–water experiment, the ADETEL air–water and steam–water experiments, and the full-scale FATE air–water experiment. The prediction matches the measure data well especially in the full-scale FATE experiments. The comparison results also confirmed the scalability of the horizontal stratification model with the applicability of the horizontal stratification criterion to the full-scale PWR condition. The uncertainty factors that impact the depressurization system entrainment onset are discussed for the future improvements. This work provides the direction to accurately model the entrainment onset for LPDS and improve the simulation of LOCA in advanced passive PWRs.

Experimental addition of nitrogen to a whole forest ecosystem at Gårdsjön, Sweden (NITREX): Nitrate leaching during 26 years of treatment

Chronic high deposition of nitrogen (N) to forest ecosystems can lead to increased leaching of inorganic N to surface waters, enhancing acidification and eutrophication. For 26 years nitrogen has been added as ammonium nitrate (NH₄NO₃) at 40 kg N ha^-1 yr^-1 to a whole forested catchment ecosystem at Gårdsjön, Sweden, to experimentally simulate the transition from a N-limited to N-rich state. Over the first 10 years of treatment there was an increasing amount of nitrate (NO₃^-) and to a lesser extent ammonium (NH₄⁺) lost in runoff, but then N leaching stabilised, and for the subsequent 16 years the fraction of N added lost in runoff remained at 9%. NO₃^- concentrations in runoff were low in the summer during the first years of treatment, but now are high throughout the year. High frequency sampling showed that peaks in NO₃^- concentrations generally occurred with high discharge, and were enhanced if high discharge coincided with occasions of N addition. Approximately 50% of the added N has gone to the soil. The added N is equivalent to 140 years of ambient N deposition. At current ambient levels of N deposition there thus appears to be no immediate risk of N saturation at this coniferous forest ecosystem, and by inference to other such N-limited forests in Scandinavia.

Effects of multiple stresses hydropower, acid deposition and climate change on water chemistry and salmon populations in the River Otra, Norway

Many surface waters in Europe suffer from the adverse effects of multiple stresses. The Otra River, southernmost Norway, is impacted by acid deposition, hydropower development and increasingly by climate change. The river holds a unique population of land-locked salmon and anadromous salmon in the lower reaches. Both populations have been severely affected by acidification. The decrease in acid deposition since the 1980s has led to partial recovery of both populations. Climate change with higher temperatures and altered precipitation can potentially further impact fish populations. We used a linked set of process-oriented models to simulate future climate, discharge, and water chemistry at five sub-catchments in the Otra river basin. Projections to year 2100 indicate that future climate change will give a small but measureable improvement in water quality, but that additional reductions in acid deposition are needed to promote full restoration of the fish communities. These results can help guide management decisions to sustain key salmon habitats and carry out effective long-term mitigation strategies such as liming. The Otra River is typical of many rivers in Europe in that it fails to achieve the good ecological status target of the EU Water Framework Directive. The programme of measures needed in the river basin management plan necessarily must consider the multiple stressors of acid deposition, hydropower, and climate change. This is difficult, however, as the synergistic and antagonistic effects are complex and challenging to address with modelling tools currently available.

Assessment of Device-Related Thrombus and Associated Clinical Outcomes With the WATCHMAN Left Atrial Appendage Closure Device for Embolic Protection in Patients With Atrial Fibrillation (from the PROTECT-AF Trial)

Left atrial appendage closure with the WATCHMAN device is an alternative to anticoagulation for stroke prevention in selected patients with atrial fibrillation (AF). LA device-related thrombus (DRT) is poorly defined and understood. We aimed to (1) develop consensus echocardiographic diagnostic criteria for DRT; (2) estimate the incidence of DRT; and (3) determine clinical event rates in patients with DRT. In phase 1 (training), a training manual was developed and reviewed by 3 echocardiographers with left atrial appendage closure device experience. All available transesophageal (TEE) studies in the WATCHMAN left atrial appendage system for embolic protection in patients with atrial fibrillation (PROTECT-AF) trial patients with suspected DRT were reviewed in 2 subsequent phases. In phase 2 (primary blind read), each reviewer independently scored each study for DRT, and final echo criteria were developed. Unanimously scored studies were considered adjudicated, whereas all others were reevaluated by all reviewers in phase 3 (group adjudication read). DRT was suspected in 35 of 485 patients by the site investigator, the echocardiography core laboratory, or both; 93 of the individual TEE studies were available for review. In phase 2, 3 readers agreed on 67 (72%) of time points. Based on phases 1 and 2, 5 DRT criteria were developed. In phase 3, studies without agreement in phase 2 were adjudicated using these criteria. Overall, at least 1 TEE was DRT positive in 27 (5.7%) PROTECT-AF patients. Stroke, peripheral embolism, or cardiac/unexplained death occurred in subjects with DRT at a rate of 3.4 per 100 patient-years follow-up. In conclusion, DRT were identified on at least 1 TEE in 27 PROTECT-AF patients, indicating a DRT incidence of 5.7%. Primary efficacy events in patients with DRT occurred at a rate of 3.4 per 100 patient-years follow-up, intermediate in frequency between event rates previously reported for the overall device and warfarin arms in PROTECT-AF.

Modelling inorganic nitrogen in runoff: Seasonal dynamics at four European catchments as simulated by the MAGIC model

Nitrogen (N) deposition is globally considered as a major threat to ecosystem functioning with important consequences for biodiversity, carbon sequestration and N retention. Lowered N retention as manifested by elevated concentrations of inorganic N in surface waters indicates ecosystem N saturation. Nitrate (NO3) concentrations in runoff from semi-natural catchments typically show an annual cycle, with low concentrations during the summer and high concentrations during the winter. Process-oriented catchment-scale biogeochemical models provide tools for simulation and testing changes in surface water and soil chemistry in response to changes in sulphur (S) and N deposition and climate. Here we examine the ability of MAGIC to simulate the observed monthly as well as the long-term trends over 10-35 years of inorganic N concentrations in streamwaters from four monitored headwater catchments in Europe: Čertovo Lake in the Czech Republic, Afon Gwy at Plynlimon, UK, Storgama, Norway and G2 NITREX at Gårdsjön, Sweden. The balance between N inputs (mineralization+deposition) and microbial immobilization and plant uptake defined the seasonal pattern of NO3 leaching. N mineralization and N uptake were assumed to be governed by temperature, described by Q10 functions. Seasonality in NO3 concentration and fluxes were satisfactorily reproduced at three sites (R2 of predicted vs. modelled concentrations varied between 0.32 and 0.47 and for fluxes between 0.36 and 0.88). The model was less successful in reproducing the observed NO3 concentrations and fluxes at the experimental N addition site G2 NITREX (R2=0.01 and R2=0.19, respectively). In contrast to the three monitored sites, Gårdsjön is in a state of change from a N-limited to N-rich ecosystem due to 20 years of experimental N addition. At Gårdsjön the measured NO3 seasonal pattern did not follow typical annual cycle for reasons which are not well understood, and thus not simulated by the model.

CAPSULE

The MAGIC model is able to simulate NO3 leaching on a monthly as well as an annual basis, and thus to reproduce the seasonal and short-term variations in N dynamics.

Abstract 142: Primary Endpoint Results from a Community-Based Registry Evaluating the Use of a Blood-Based Age/Sex/Gene Expression Test in Patients Presenting with Symptoms Suggestive of Obstructive Coronary Artery Disease: the PRESET Registry (A Registry to Evaluate Patterns of Care Associated with the Use of Corus® CAD in Real World Clinical Care Settings)

Background: Patients with symptoms suggestive of obstructive coronary artery disease (CAD) frequently undergo unnecessary testing and procedures. Approximately $5.9 billion/year is spent on non-invasive and invasive cardiac testing among non-diabetic patients in the US without a prior revascularization or myocardial infarction, yet clinicians are often unable to confidently determine the primary etiology of symptoms suggestive of obstructive CAD. A previously validated blood-based test, incorporating age, sex, and gene expression levels into an algorithmic score, has been shown to have a 96% NPV and can inform the current likelihood of CAD in a symptomatic patient.

Objective: The objective of the PRESET Registry is to evaluate the use of an age/sex/gene expression score (ASGES) and its effects on medical decision-making, with a focus on referrals to cardiology or advanced cardiac testing, in a community-based cardiovascular registry.

Methods: The prospective PRESET Registry (NCT01677156) enrolled stable, non-acute adult patients without a history of CAD from 21 US primary care practices from September 2012 to August 2014. Primary care clinicians provided the pre- and post-ASGES diagnosis and evaluation plan for each patient. Demographics, clinical factors, and ASGES results (predefined as low [ASGES ≤15] or elevated [ASGES >15]) were collected, as were management plans post-ASGES testing, including referrals to cardiology or further functional/anatomic (ETT, MPI, CTCA, stress echo, ICA) cardiac testing. Patients were followed to 30 days post-ASGES for the primary analysis of the association between ASGES and subsequent cardiac testing. Up to 1 year follow-up will be conducted for all patients.

Results: Among the evaluable cohort of 718 patients, 369 (51%) were women, the median age was 58 and the median BMI was 30. The median ASGES was 18 (range, 1-40), and 310 patients (43%) had low scores. Thirty days after testing, 27 of 310 (9%) patients with low scores were referred to cardiology or advanced diagnostic testing, while 143 of 408 (35%) patients with elevated scores were referred (OR 0.18, p<0.0001). With regard to adverse outcomes, there were 2 events (stroke/TIA) overall, which were judged to be unrelated to the study procedure.

Conclusion: In this analysis of a community-based cardiovascular registry, the age/ex/gene expression test was adopted in clinical practice and associated with a statistically significant and clinically relevant effect on medical decision making in patients presenting with typical or atypical symptoms suggestive of obstructive CAD. The use of the ASGES test showed clinical utility in helping clinicians efficiently and safely rule out obstructive CAD as the cause of their patients’ symptoms, thereby minimizing potentially unnecessary referral of low risk patients to cardiology and further cardiac diagnostic testing.

Assessing recovery from acidification of European surface waters in the year 2010: evaluation of projections made with the MAGIC model in 1995

In 1999 we used the MAGIC (Model of Acidification of Groundwater In Catchments) model to project acidification of acid-sensitive European surface waters in the year 2010, given implementation of the Gothenburg Protocol to the Convention on Long-Range Transboundary Air Pollution (LRTAP). A total of 202 sites in 10 regions in Europe were studied. These forecasts can now be compared with measurements for the year 2010, to give a "ground truth" evaluation of the model. The prerequisite for this test is that the actual sulfur and nitrogen deposition decreased from 1995 to 2010 by the same amount as that used to drive the model forecasts; this was largely the case for sulfur, but less so for nitrogen, and the simulated surface water [NO3(-)] reflected this difference. For most of the sites, predicted surface water recovery from acidification for the year 2010 is very close to the actual recovery observed from measured data, as recovery is predominantly driven by reductions in sulfur deposition. Overall these results show that MAGIC successfully predicts future water chemistry given known changes in acid deposition.

Modelling phosphorus loading and algal blooms in a Nordic agricultural catchment-lake system under changing land-use and climate

A model network comprising climate models, a hydrological model, a catchment-scale model for phosphorus biogeochemistry, and a lake thermodynamics and plankton dynamics model was used to simulate phosphorus loadings, total phosphorus and chlorophyll concentrations in Lake Vansjø, Southern Norway. The model network was automatically calibrated against time series of hydrological, chemical and biological observations in the inflowing river and in the lake itself using a Markov Chain Monte-Carlo (MCMC) algorithm. Climate projections from three global climate models (GCM: HadRM3, ECHAM5r3 and BCM) were used. The GCM model HadRM3 predicted the highest increase in temperature and precipitation and yielded the highest increase in total phosphorus and chlorophyll concentrations in the lake basin over the scenario period of 2031-2060. Despite the significant impact of climate change on these aspects of water quality, it is minimal when compared to the much larger effect of changes in land-use. The results suggest that implementing realistic abatement measures will remain a viable approach to improving water quality in the context of climate change.

Amines and amine-related compounds in surface waters: a review of sources, concentrations and aquatic toxicity

This review compiles available information on the concentrations, sources, fate and toxicity of amines and amine-related compounds in surface waters, including rivers, lakes, reservoirs, wetlands and seawater. There is a strong need for this information, especially given the emergence of amine-based post-combustion CO2 capture technologies, which may represent a new and significant source of amines to the environment. We identify a broad range of anthropogenic and natural sources of amines, nitrosamines and nitramines to the aquatic environment, and identify some key fate and degradation pathways of these compounds. There were very few data available on amines in surface waters, with reported concentrations often below detection and only rarely exceeding 10 μg/L. Reported concentrations for seawater and reservoirs were below detection or very low, while for lakes and rivers, concentrations spanned several orders of magnitude. The most prevalent and commonly detected amines were methylamine (MA), dimethylamine (DMA), ethylamine (EA), diethylamine (DEA) and monoethanolamine (MEAT). The paucity of data may reflect the analytical challenges posed by determination of amines in complex environmental matrices at ambient levels. We provide an overview of available aquatic toxicological data for amines and conclude that at current environmental concentrations, amines are not likely to be of toxicological concern to the aquatic environment, however, the potential for amines to act as precursors in the formation of nitrosamines and nitramines may represent a risk of contamination of drinking water supplies by these often carcinogenic compounds. More research on the prevalence and toxicity of amines, nitrosamines and nitramines in natural waters is necessary before the environmental impact of new point sources from carbon capture facilities can be adequately quantified.

Modeling past and future acidification of Swedish lakes

Decades of acid deposition have caused acidification of lakes in Sweden. Here we use data for 3000 lakes to run the acidification model MAGIC and estimate historical and future acidification. The results indicate that beginning in about 1920 a progressively larger number of lakes in Sweden fell into the category of "not naturally acidified" (∆pH > 0.4). The peak in acidification was reached about 1985; since then many lakes have recovered in response to lower levels of acid deposition. Further recovery from acidification will occur by the year 2030 given implementation of agreed legislation for emissions of sulphur (S) and nitrogen (N) in Europe. But the number of catchments with soils being depleted in base cations will increase slightly. MAGIC-reconstructed history of acidification of lakes in Sweden agrees well with information on fish populations. Future acidification of Swedish lakes can be influenced by climate change as well as changes in forest harvest practices.

Modelling soil nitrogen: the MAGIC model with nitrogen retention linked to carbon turnover using decomposer dynamics

We present a new formulation of the acidification model MAGIC that uses decomposer dynamics to link nitrogen (N) cycling to carbon (C) turnover in soils. The new model is evaluated by application to 15-30 years of water chemistry data at three coniferous-forested sites in the Czech Republic where deposition of sulphur (S) and N have decreased by >80% and 40%, respectively. Sulphate concentrations in waters have declined commensurately with S deposition, but nitrate concentrations have shown much larger decreases relative to N deposition. This behaviour is inconsistent with most conceptual models of N saturation, and with earlier versions of MAGIC which assume N retention to be a first-order function of N deposition and/or controlled by the soil C/N ratio. In comparison with earlier versions, the new formulation more correctly simulates observed short-term changes in nitrate leaching, as well as long-term retention of N in soils. The model suggests that, despite recent deposition reductions and recovery, progressive N saturation will lead to increased future nitrate leaching, ecosystem eutrophication and re-acidification.

Reducing cardiorenal risk through combination therapy with a direct renin inhibitor

Interruption of the renin-angiotensin-aldosterone system (RAAS) cascade with angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), or more recently direct renin inhibitors (DRIs) is a safe and effective antihypertensive strategy that is in routine clinical use. The clinical utility of these agents in cardiorenal end-organ protection is increasingly being recognized. Although both ACE inhibitors and ARBs demonstrate substantial benefit in patients with cardiovascular and/or renal disease, considerable evidence indicates that they only partially suppress the RAAS pathway due to feedback upregulation of plasma renin activity. With the goal of providing more comprehensive RAAS blockade, combination ACE inhibitor/ARB therapy has been evaluated. However, this approach has not shown the anticipated improvements in composite cardiovascular and renal outcomes and appears to be associated with significant toxicity. Due to a unique mechanism of action, the combination of a DRI with an ACE inhibitor or ARB may represent an effective end-organ-protective therapeutic strategy.

Chemical and biological recovery of Lake Saudlandsvatn, a formerly highly acidified lake in southernmost Norway, in response to decreased acid deposition

We studied acid-sensitive organisms in Lake Saudlandsvatn in southernmost Norway in relation to acidification: brown trout (Salmo trutta), the caddisfly Hydropsyche siltalai and the zooplankter Daphnia longispina. The study lake was highly acidified with episodic pH depressions <5.0 in the 1970s and 1980s, and sulphur (S) deposition five times greater than the critical load. Chemical recovery following reduced deposition of S became evident in the late 1990s, when the pH increased to 5.5-6.0. By 2000, S deposition had decreased to the critical load. The lake sustained a good brown trout population until the early 1980s, but then it started to decline and nearly went extinct ten years later. Severe recruitment failures were found in most years prior to 1995, both in the inlet and outlet stream. However, since 2003 a marked recovery of the brown trout population has occurred in the lake. During the 1980s, the H. siltalai disappeared from the lake tributaries. In 1996, the species reappeared, and increased highly in abundance from 2000 and onwards. The first post-acidification record of D. longispina from net hauls in Lake Saudlandsvatn was in 2002. Palaeolimnological data confirmed their presence prior to acidification. Any significant recovery in all three organism groups coincided with an acid-neutralizing capacity (ANC) of >20 μeq L⁻¹ and toxic inorganic aluminium of <30 μg L⁻¹. Projections made with the MAGIC model indicate that unless further reductions in deposition of S are made, the ANC will fluctuate around the ANC survival threshold for the biological elements described. Thus, full biological recovery will not occur in the near future.

Nitrogen leaching and acidification during 19 years of NH₄NO₃ additions to a coniferous-forested catchment at Gårdsjön, Sweden (NITREX)

The role of nitrogen (N) in acidification of soil and water has become relatively more important as the deposition of sulphur has decreased. Starting in 1991, we have conducted a whole-catchment experiment with N addition at Gårdsjön, Sweden, to investigate the risk of N saturation. We have added 41 kg N ha(-1) yr(-1) as NH(4)NO(3) to the ambient 9 kg N ha(-1) yr(-1) in fortnightly doses by means of sprinkling system. The fraction of input N lost to runoff has increased from 0% to 10%. Increased concentrations of NO(3) in runoff partially offset the decreasing concentrations of SO(4) and slowed ecosystem recovery from acid deposition. From 1990-2002, about 5% of the total N input went to runoff, 44% to biomass, and the remaining 51% to soil. The soil N pool increased by 5%. N deposition enhanced carbon (C) sequestration at a mean C/N ratio of 42-59 g g(-1).

Modeling future acidification and fish populations in Norwegian surface waters

Despite great progress made in the past 25 years, acid deposition continues to cause widespread damage to the environment in Europe and eastern North America. Legislation to limit emissions of sulfur and nitrogen compounds in Europe is now under revision. The most recent protocol was based in part on the critical loads concept. The new protocol may also take into consideration the time delays between dose and response inherent in natural ecosystems. Policy decisions to reduce adverse effects on ecosystems entail a trade-off: quick response will require deeper cuts in emissions and thus higher costs, whereas lower costs with lesser cuts in emissions will give slower response. Acidification of lakes and damage to fish populations in Norway is used as an example. Under current legislation for emission reductions, surface waters will continue to slowly recover, but for many decades lakes in about 18% of Norway will continue to have water quality insufficient to support healthy populations of brown trout and other indicator organisms. Additional emission reductions can speed up the rate and degree of recovery.

Effect of climate change on fluxes of nitrogen from the Tovdal River basin, Norway, to adjoining marine areas

The mass transport model TEOTIL was used to project nitrate (NO3) fluxes from the Tovdal River basin, southernmost Norway, given four scenarios of climate change. Forests, uplands, and open water currently account for 90% of the NO3 flux. Climate scenarios for 2071-2100 suggest increased temperature by 2-4 degrees C and precipitation by 3-11%. Climate experiments and long-term monitoring were used to estimate future rates of nitrogen (N) leaching. More water will run through the terrestrial catchments during the winter but less will run in the spring. The annual NO3 flux from the Tovdal River to the adjoining Topdalsfjord is projected to remain unchanged, but with more NO3 delivered in the winter and less in the spring. Algal blooms in coastal waters can be expected to occur earlier in the year. Major sources of uncertainty are in the long-term fate of N stored in soil organic matter and the impacts of forest management.

Effect of climate change on flux of N and C: air-land-freshwater-marine links: synthesis

Projected climate change might increase the deposition of nitrogen by about 10% to seminatural ecosystems in southern Norway. At Storgama, increased precipitation in the growing season increased the fluxes of total organic carbon (TOC) and total organic nitrogen (TON) in proportion to the water flux. In winter, soil temperatures near 0 degrees C, common under a snowpack, induced higher runoff of inorganic nitrogen (N) and lower runoff of TOC. By contrast, soil temperatures below freezing, caused by little snow accumulation (expected in a warmer world), reduced runoff of inorganic N, TON, and TOC. Long-term monitoring data showed that reduced snowpack can cause either decreased or increased N leaching, depending on interactions with N deposition, soil temperature regime, and winter discharge. Seasonal variation in TOC was mainly climatically controlled, whereas deposition of sulfate and nitrate (NO3) explained the long-term TOC increase. Upscaling to the river basin scale showed that the annual flux of NO3 will remain unchanged in response to climate change projections.

Projected stream water fluxes of NO3 and total organic carbon from the Storgama headwater catchment, Norway, under climate change and reduced acid deposition

Fluctuations in the 20-year record of nitrate (NO3) and total organic carbon (TOC) concentrations and fluxes in runoff at the small headwater catchment Storgama, southern Norway, were related to climate and acid deposition. The long-term decline in NO3 related to reduced NO3 deposition and increased winter discharge, whereas the long-term increase in TOC related to reduced sulfur deposition. Multiple regression models describing long-term trends and seasonal variability in these records were used to project future concentrations given scenarios of climate change and acid deposition. All scenarios indicated reduced NO3 fluxes and increased TOC fluxes; the largest projected changes for the period 2071-2100 were -86% and +24%, respectively. Uncertainties are that the predicted future temperatures are considerably higher than the historical record. Also, nonlinear responses of ecosystem processes (nitrogen [N] mineralization) to temperature, N-enrichment of soils, and step-changes in environmental conditions may affect future leaching of carbon and N.

Manipulation of snow in small headwater catchments at Storgama, Norway: effects on leaching of inorganic nitrogen

We have manipulated the winter-time soil temperature regime of small headwater catchments in a montane heathland area of southern Norway to study the possible effects on concentrations and fluxes of inorganic nitrogen in runoff. The experiments included extra insulation of soils in two catchments to prevent subzero temperatures during winter, and removal of snow in two other catchments to promote soil frost. Increased soil temperatures during winter increased the springtime concentrations and fluxes of ammonium (NH4) and nitrate (NO3) in runoff. By contrast, snow removal with development of significant soil frost showed no systematic effects on mean concentrations or fluxes of inorganic N. The results from our experiments suggest that warmer soils during winter caused by exceptionally mild winters, or alternatively a heavy snowpack, imply a greater risk for inorganic N leaching in this region than a possible increase of soil frost events because of reduced snow cover.

Use of (15)N-labelled nitrogen deposition to quantify the source of nitrogen in runoff at a coniferous-forested catchment at Gårdsjön, Sweden

To determine the source of dissolved inorganic nitrogen (N) in runoff, approx. 35kg N enriched with the stable isotope (15)N (2110 per thousand delta(15)N) was added to a mature coniferous forested catchment for one whole year. The total N input was approx. 50kg ha(-1) year(-1). The enrichment study was part of a long-term whole-catchment ammonium nitrate addition experiment at Gårdsjön, Sweden. The (15)N concentrations in precipitation, throughfall, runoff and upper forest floor were measured prior to, during, and 3-9years following the (15)N addition. During the year of the (15)N addition the delta(15)N level in runoff largely reflected the level in incoming N, indicating that the leached NO(3)(-) came predominantly from precipitation. Only 1.1% of the incoming N was lost during the year of the tracer addition. The cumulative loss of tracer N over a 10-year period was only 3.9% as DIN and 1.1% as DON.

Increased nitrogen in runoff and soil following 13 years of experimentally increased nitrogen deposition to a coniferous-forested catchment at Gårdsjön, Sweden

Beginning in 1991, we have added nitrogen (N) to the 0.5-ha, N-poor, coniferous-forested catchment G2 NITREX at Gårdsjön, Sweden, to investigate the consequences of chronic elevated N deposition. We have added 40 kg N ha-1 yr-1 in fortnightly doses of NH4NO3 to the ambient 15 kg N ha-1 yr-1 by means of a sprinkling system. NO3 concentrations in runoff increased during 13 years from<1 to 70 microeq L-1, and in 2004 comprised about 10% of N input. Inhibition of NO3 immobilisation due to increased availability of NH4 might explain the increased leaching of NO3. C and N pools in the forest floor increased but C/N ratio has not changed. The increase in NO3 leaching thus occurred independently of change in C/N ratio. The results from Gårdsjön demonstrate that increased leaching of inorganic N and decrease in C/N ratio respond to increased N deposition at greatly different time scales.

Modelling the effect of climate change on recovery of acidified freshwaters: relative sensitivity of individual processes in the MAGIC model

The MAGIC model was used to evaluate the relative sensitivity of several possible climate-induced effects on the recovery of soil and surface water from acidification. A common protocol was used at 14 intensively studied sites in Europe and eastern North America. The results show that several of the factors are of only minor importance (increase in pCO(2) in soil air and runoff, for example), several are important at only a few sites (seasalts at near-coastal sites, for example) and several are important at nearly all sites (increased concentrations of organic acids in soil solution and runoff, for example). In addition changes in forest growth and decomposition of soil organic matter are important at forested sites and sites at risk of nitrogen saturation. The trials suggest that in future modelling of recovery from acidification should take into account possible concurrent climate changes and focus specially on the climate-induced changes in organic acids and nitrogen retention.

Linked models to assess the impacts of climate change on nitrogen in a Norwegian river basin and FJORD system

Dynamically downscaled data from two Atmosphere-Ocean General Circulation Models (AOGCMs), ECHAM4 from the Max-Planck Institute (MPI), Germany and HadAm3H from the Hadley Centre (HAD), UK, driven with two scenarios of greenhouse gas emissions (IS92a and A2, respectively) were used to make climate change projections. These projections were then used to drive four effect models linked to assess the effects on hydrology, and nitrogen (N) concentrations and fluxes, in the Bjerkreim river basin (685-km(2)) and its coastal fjord, southwestern Norway. The four effect models were the hydrological model HBV, the water quality models MAGIC, INCA-N and the NIVA FJORD model. The downscaled climate scenarios project a general temperature increase in the study region of approximately 1 degrees C by 2030-2049 (MPI IS92a) and approximately 3 degrees C by 2071-2100 (HAD A2). Both scenarios imply increased winter precipitation, whereas the projections of summer and autumn precipitation are quite different, with the MPI scenario projecting a slight increase and the HAD scenario a significant decrease. As a response to increased winter temperature, the HBV model simulates a dramatic reduction of snow accumulation in the upper parts of the catchment, which in turn lead to higher runoff during winter and lower runoff during snowmelt in the spring. With the HAD scenario, runoff in summer and early autumn is substantially reduced as a result of reduced precipitation, increased temperatures and thereby increased evapotranspiration. The water quality models, MAGIC and INCA-N project no major changes in nitrate (NO(3)(-)) concentrations and fluxes within the MPI scenario, but a significant increase in concentrations and a 40-50% increase in fluxes in the HAD scenario. As a consequence, the acidification of the river could increase, thus offsetting ongoing recovery from acidification due to reductions in acid deposition. Additionally, the increased N loading may stimulate growth of N-limited benthic algae and macrophytes along the river channels and lead to undesirable eutrophication effects in the estuarine area. Simulations made by the FJORD model and the HAD scenario indicate that primary production in the estuary might increase up to 15-20%, based on the climate-induced changes in river flow and nitrate concentrations alone.

Newer molecular approaches to detect known viruses and previously unrecognized viruses in cell substrates

The theme of this brief presentation is that there are tremendous advances not only in PCR-based detection but in other novel ways of detecting viruses and other agents. Much of the research is now being driven by the bio-defence agenda. Somehow those with manufacturing and regulatory responsibilities have to keep abreast of these developments and incorporate them as they become available into defining the safety of cell substrates. I am concerned that these techniques are and may remain academic research tools without validation or standardization, and that individual academic laboratories will not develop the capacity and special skills necessary to satisfy regulatory requirements, but that there is a tremendous research incentive in this area that needs to be linked with the development of safe prophylactic and therapeutic biologicals. With that, I will finish what I would consider as a report rather than an original talk.

Long-term trends and spatial variability in nitrate leaching from alpine catchment-lake ecosystems in the Tatra Mountains (Slovakia-Poland)

Relationships between catchment characteristics of 31 alpine lakes and observed trends in lake water concentrations of nitrate were evaluated in the Tatra Mountains. Nitrate concentrations increased from background levels <4 microeql(-1) in the 1930s to maxima (up to 55 microeql(-1)) in the 1980s, after which they declined to 4-44 microeql(-1) by the late 1990s. In-lake nitrate concentrations correlated negatively with parameters characterising catchment-weighted mean pools (CWM; kgm(-2)) of soil, i.e. with percent land cover with meadow and soil depth, and positively with grade of terrain, annual precipitation, and the highest elevation in the catchment. The CWM pool of soil and annual precipitation explained together 65% of the current spatial variability in nitrate concentrations. Denitrification and direct N deposition on surface area explained 14% of the variability. Increased atmospheric N deposition and declining net N retention in soils were responsible for long-term changes in nitrate concentrations. Long-term decline in %N retention in soils decreased along with the estimated decline in C:N ratios (from 21 to 18 on average during the last 70 years). An empirical model linking nitrate concentrations in different types of alpine Tatra Mountain lakes to four independent variables (CWM soil pool, annual precipitation, increased N deposition, and average trend in soil C:N ratios) explained 80% of the observed spatial and temporal nitrate variability over the period 1937-2000.

Therapies for Preventing Heart Failure

Heart failure is an increasingly common syndrome. Despite numerous advances in the treatment of patients with established heart failure, the prevalence and economic burden of the disease will continue to escalate as long as the number of patients with heart failure continues to increase. Much effort has been directed at developing and refining expensive therapies for the small number of patients with advanced heart failure; these efforts will offer little benefit to public health. Simple preventive strategies have been shown to reduce the likelihood of heart failure. Widespread use of these strategies would result in substantial improvement in community health and reduction in societal cost for a disease that will otherwise prove increasingly burdensome.

Terrestrial ecosystem recovery--modelling the effects of reduced acidic inputs and increased inputs of sea-salts induced by global change

The reduced emissions of acidifying sulfur and nitrogen in Europe since the late 1970s will be further reduced when the Gothenburg protocol is fully implemented by 2010. Here we address the consequences for the recovery of acidified terrestrial ecosystems using the acidification model MAGIC applied to 3 large-scale "clean rain" experiments, the so-called roof experiments at Risdalsheia, Norway; Gårdsjön, Sweden, and Klosterhede, Denmark. Implementation of the Gothenburg protocol will initiate recovery of the soils at all 3 sites by rebuilding base saturation. The rate of recovery is small and base saturation increases less than 5% over the next 30 years. A climate-induced increase in storm severity will increase the sea-salt input to the ecosystems. This will provide additional base cations to the soils and more than double the rate of the recovery, but also lead to strong acid pulses following high sea-salt inputs as the deposited base cations exchange with the acidity stored in the soil. Future recovery of soils and runoff at acidified catchments will thus depend on the amount and rate of reduction of acid deposition, and in the case of systems near the coast, the frequency and intensity of sea-salt episodes as well.

A radiation-shielding device for craniofacial implant placement

The use of radiation shields in the head and neck cancer patient receiving adjuvant radiation therapy is a treatment alternative for protecting anticipated prosthetic implant sites. Shields can be fabricated easily as part of an interdisciplinary treatment protocol. In this article, the methods used to fabricate an extraoral radiation shield are described, and a patient treatment that illustrates possible uses of the shield for both extraoral and intraoral sites is presented.

Modification of a Super-Sep bottle for paint-on application of a separating medium used in flasking dentures

Modifying a Super-Sep bottle by adding a brush to the lid for paint-on use allows for the precise application of the separating medium used when flasking dentures. Super-Sep offers many advantages over other commonly used separating mediums: It is virtually dimensionless, allowing for better accuracy; it dries quickly and functions best on moist stone; and it can be poured against immediately. The latter fact means less time is needed before the subsequent layers of stone can be applied when denture flasking.

Prosthodontic management of periodontally compromised patient

The fabrication and placement of a conventional immediate denture following extraction of periodontally compromised, non-restorable remaining teeth is a method that is frequently used to help restore form and function in an esthetically pleasing manner. This technique demands knowledge in applied basic sciences and prosthodontic principles. Accurate diagnosis and scrupulous treatment planning help the dentist address the patient's needs.

Effect of evaporation and mixing technique on die spacer thickness: a preliminary study

STATEMENT OF PROBLEM

Casting relief is required for proper seating of castings to allow for luting agent thickness. The application of die spacer to the die is the most common method of obtaining casting relief. Die spacer film thicknesses that are outside the ideal range of 25 to 40 microm can cause clinical problems. Thickness can be affected by the separation of die spacer constituents, which may not be reconstituted by mixing, in the bottle and by the evaporation of volatile components while the bottle is open.

PURPOSE

The purpose of this study was to determine the effects of component evaporation and die spacer mixing technique on applied die spacer thickness.

MATERIAL AND METHODS

Bottles of Gold Tru-fit die spacer were left open for 0, 1, 4, 8, and 24 hours at 22 degrees C. Spacer solutions were shaken either by hand per the manufacturer's directions or on a dental vibrator for 1 minute. One even brush stroke of spacer was applied to clean glass slides. Three die spacer films were made for each combination of time and mixing technique. Eighteen thickness measurements per sample at various sites were recorded with profilometer tracings. Statistical differences were determined with a 2-way ANOVA.

RESULTS

Handshaking provided greater die spacer thickness, which increased with the time that the bottle was open. Vibration provided lower thickness with no statistical increase with time.

CONCLUSION

Insufficient agitation caused lower film thickness. Excessive evaporation caused higher film thickness.

Surface water acidification in the South Pennines I. Current status and spatial variability

The South Pennines, an area of acid-sensitive geology at the centre of a major industrial region, have undergone perhaps the most severe historic exposure to sulphur and nitrogen deposition in the UK. This study addresses a lack of existing research on the region by presenting the findings of a survey of 62 surface waters sampled during a 1-week period in April 1998. Results indicate that acidification in the region is acute; 27 of the sampled surface waters had a negative acid neutralising capacity (ANC) and 28 had a pH below 5.0. Minimum recorded pH values were below 4.0. Non-marine sulphate levels were extremely high (median 222 microeq/1), and widespread high nitrate concentrations (median 41 microeq/1) suggest that soils in the region as a whole may be at an advanced stage of nitrogen saturation. A consistent relationship was identified between site acidity and the balance between the major weathering-derived cations, calcium and magnesium, and sulphate. This could in turn be linked to catchment soil type and land use, with the most acidic conditions occurring in peat-dominated catchments, where weathering is minimal and the influence of atmospheric deposition most pronounced. Percentage of peat in each catchment was the single best predictor of surface water acidity. Nitrate concentrations, although not a dominant control on acidity, varied significantly according to land use. Elevated concentrations were observed in catchments containing forestry, due to enhanced deposition inputs, and in catchments containing improved land, linked to fertiliser use. Ammonium concentrations, although low at most catchments, were a significant component of the inorganic nitrogen total in a number of surface waters draining waterlogged peat catchments.

Clinical decision making in patients with congestive heart failure: the role of thoracic electrical bioimpedance

Optimizing appropriate pharmacologic therapy in patients with congestive heart failure has been difficult due to a lack of easily obtainable hemodynamic information to guide the approach to the patient. Recently, thoracic electrical bioimpedance has allowed reliable outpatient determination of these hemodynamic variables, potentially allowing tailored adjustment of therapy in patients with cardiac dysfunction. Case studies are presented in which bioimpedance data were important contributing factors in optimizing patient management. Utilization of this new technology to individualize patient therapy should lead to improved outcomes and more efficient use of health care resources. (c)2000 by CHF, Inc.

A technique to create appropriate abutment tooth contours for removable partial dentures

A technique is presented for using light-cured composite resin to create desirable contours on abutment teeth for the retention and support of removable partial dentures. The desired tooth shape is created on a diagnostic cast, captured in a clear temporary splint material, and formed in resin on the abutment teeth with the splint acting as a matrix.

Multidisciplinary treatment for an implant retained auricular prosthesis rehabilitation

Retention of a facial prosthesis is the most important factor in creating a useful prosthesis for the patient. This paper presents a detailed case study of an auricular defect that was rehabilitated using two types of prosthetic retention: adhesive and osseointegration. We present the patient selection criteria, the surgical considerations prior to implant placement, retention component selection, prosthetic fabrication techniques and patient management after prosthetic delivery. The osseointegrated prosthesis made a large improvement in the patient's quality of life.