The impact of acid deposition and forest harvesting on lakes and their forested catchments in south central Ontario: a critical loads approach

International audienceThe impact of acid deposition and tree harvesting on three lakes and their representative sub-catchments in the Muskoka-Haliburton region of south-central Ontario was assessed using a critical loads approach. As nitrogen dynamics in forest soils are complex and poorly understood, for simplicity and to allow comparison among lakes and their catchments, CLs (A) for both lakes and forest soils were calculated assuming that nitrate leaching from catchments will not change over time (i.e. a best case scenario). In addition, because soils in the region are shallow, base cation weathering rates for the representative sub-catchments were calculated for the entire soil profile and these estimates were also used to calculate critical loads for the lakes. These results were compared with critical loads obtained by the Steady State Water Chemistry (SSWC) model. Using the SSWC model, critical loads for lakes were between 7 and 19 meq m-2yr-1 higher than those obtained from soil measurements. Lakes and forests are much more sensitive to acid deposition if forests are harvested, but two acid-sensitive lakes had much lower critical loads than their respective forested sub-catchments implying that acceptable acid deposition levels should be dictated by the most acid-sensitive lakes in the region. Under conditions that assume harvesting, the CL (A) is exceeded at two of the three lakes and five of the six sub-catchments assessed in this study. However, sulphate export from catchments greatly exceeds input in bulk deposition and, to prevent lakes from falling below the critical chemical limit, sulphate inputs to lakes must be reduced by between 37% and 92% if forests are harvested. Similarly, sulphate leaching from forested catchments that are harvested must be reduced by between 16 and 79% to prevent the ANC of water draining the rooting zone from falling below 0 ?eq l-1. These calculations assume that extremely low calcium leaching losses (9?27 ?eq l-1) from forest soils can be maintained without any decrease in forest productivity. Calcium concentrations in the three lakes have decreased by between ?10 and 25% over the past 20 years and calculations assume that calcium concentrations in lakes can fall to around 30% of their current values without any harmful effects on biota. Both these assumptions require urgent investigation. Keywords: acid deposition, calcium, critical loads, forests, harvesting, lakes</p

Graduates from a traditional medical curriculum evaluate the effectiveness of their medical curriculum through interviews

<p>Abstract</p> <p>Background</p> <p>In 1996 The University of Liverpool reformed its medical course from a traditional lecture-based course to an integrated PBL curriculum. A project has been underway since 2000 to evaluate this change. Part of this project has involved gathering retrospective views on the relevance of both types of undergraduate education according to graduates. This paper focuses on the views of traditional Liverpool graduates approximately 6 years after graduation.</p> <p>Methods</p> <p>From February 2006 to June 2006 interviews took place with 46 graduates from the last 2 cohorts to graduate from the traditional Liverpool curriculum.</p> <p>Results</p> <p>The graduates were generally happy with their undergraduate education although they did feel there were some flaws in their curriculum. They felt they had picked up good history and examination skills and were content with their exposure to different specialties on clinical attachments. They were also pleased with their basic science teaching as preparation for postgraduate exams, however many complained about the overload and irrelevance of many lectures in the early years of their course, particular in biochemistry. There were many different views about how they integrated this science teaching into understanding disease processes and many didn't feel it was made relevant to them at the time they learned it. Retrospectively, they felt that they hadn't been clinically well prepared for the role of working as junior doctor, particularly the practical aspects of the job nor had enough exposure to research skills. Although there was little communication skills training in their course they didn't feel they would have benefited from this training as they managed to pick up had the required skills on clinical attachments.</p> <p>Conclusion</p> <p>These interviews offer a historical snapshot of the views of graduates from a traditional course before many courses were reformed. There was some conflict in the interviews about the doctors enjoying their undergraduate education but then saying that they didn't feel they received good preparation for working as a junior doctor. Although the graduates were happy with their undergraduate education these interviews do highlight some of the reasons why the traditional curriculum was reformed at Liverpool.</p

An evaluation of the performance in the UK Royal College of Anaesthetists primary examination by UK medical school and gender

<p>Abstract</p> <p>Background</p> <p>There has been comparatively little consideration of the impact that the changes to undergraduate curricula might have on postgraduate academic performance. This study compares the performance of graduates by UK medical school and gender in the Multiple Choice Question (MCQ) section of the first part of the Fellowship of the Royal College of Anaesthetists (FRCA) examination.</p> <p>Methods</p> <p>Data from each sitting of the MCQ section of the primary FRCA examination from June 1999 to May 2008 were analysed for performance by medical school and gender.</p> <p>Results</p> <p>There were 4983 attempts at the MCQ part of the examination by 3303 graduates from the 19 United Kingdom medical schools. Using the standardised overall mark minus the pass mark graduates from five medical schools performed significantly better than the mean for the group and five schools performed significantly worse than the mean for the group. Males performed significantly better than females in all aspects of the MCQ – physiology, mean difference = 3.0% (95% CI 2.3, 3.7), p < 0.001; pharmacology, mean difference = 1.7% (95% CI 1.0, 2.3), p < 0.001; physics with clinical measurement, mean difference = 3.5% (95% CI 2.8, 4.1), p < 0.001; overall mark, mean difference = 2.7% (95% CI 2.1, 3.3), p < 0.001; and standardised overall mark minus the pass mark, mean difference = 2.5% (95% CI 1.9, 3.1), p < 0.001. Graduates from three medical schools that have undergone the change from Traditional to Problem Based Learning curricula did not show any change in performance in any aspects of the MCQ pre and post curriculum change.</p> <p>Conclusion</p> <p>Graduates from each of the medical schools in the UK do show differences in performance in the MCQ section of the primary FRCA, but significant curriculum change does not lead to deterioration in post graduate examination performance. Whilst females now outnumber males taking the MCQ, they are not performing as well as the males.</p

Modelling acidification, recovery and target loads for headwater catchments in Nova Scotia, Canada

The response of twenty acid-sensitive headwater catchments in Nova Scotia to acidic deposition was investigated for the period 1850&ndash;2100 using a dynamic hydrochemical model (MAGIC: Model of Acidification of Groundwater in Catchments). To ensure robust model simulation, MAGIC was calibrated to the long-term chemical trend in annual lake observations (13&ndash;20 years). Model simulations indicated that the surface waters of all twenty catchments acidified to the 1970s but showed subsequent recovery (increases in acid neutralising capacity (ANC) and pH) as sulphate deposition decreased. However, under proposed future emissions reductions (approximately 50% of current deposition) simulated ANC and pH will not return to estimated pre-industrial levels by 2100. An ANC of 20 &mu;mol_c L^&minus;1 and pH of 5.4 were defined as acceptable chemical thresholds (or critical chemical limits) for aquatic organisms in the current study. Under the proposed emissions reductions only one catchment is predicted to remain below the critical limit for ANC by 2100; three additional catchments are predicted to remain below the critical limit for pH. Dynamic models may be used to estimate target loads, i.e., the required deposition reductions to achieve recovery within a given time. Setting target loads at approximately 30% of current depositions would allow three of the four lakes to reach the chemical criteria by 2030. In contrast to the generally good prognosis for surface waters, soils lost an average of 32% of estimated initial base saturation and recovery is estimated to be very slow, averaging 23% lower than pre-acidification levels in 2100

Views of junior doctors about whether their medical school prepared them well for work: questionnaire surveys

<p>Abstract</p> <p>Background</p> <p>The transition from medical student to junior doctor in postgraduate training is a critical stage in career progression. We report junior doctors' views about the extent to which their medical school prepared them for their work in clinical practice.</p> <p>Methods</p> <p>Postal questionnaires were used to survey the medical graduates of 1999, 2000, 2002 and 2005, from all UK medical schools, one year after graduation, and graduates of 2000, 2002 and 2005 three years after graduation. Summary statistics, chi-squared tests, and binary logistic regression were used to analyse the results. The main outcome measure was the level of agreement that medical school had prepared the responder well for work.</p> <p>Results</p> <p>Response rate was 63.7% (11610/18216) in year one and 60.2% (8427/13997) in year three. One year after graduation, 36.3% (95% CI: 34.6, 38.0) of 1999/2000 graduates, 50.3% (48.5, 52.2) of 2002 graduates, and 58.2% (56.5, 59.9) of 2005 graduates agreed their medical school had prepared them well. Conversely, in year three agreement fell from 48.9% (47.1, 50.7) to 38.0% (36.0, 40.0) to 28.0% (26.2, 29.7). Combining cohorts at year one, percentages who agreed that they had been well prepared ranged from 82% (95% CI: 79-87) at the medical school with the highest level of agreement to 30% (25-35) at the lowest. At year three the range was 70% to 27%. Ethnicity and sex were partial predictors of doctors' level of agreement; following adjustment for them, substantial differences between schools remained. In years one and three, 30% and 34% of doctors specified that feeling unprepared had been a serious or medium-sized problem for them (only 3% in each year regarded it as serious).</p> <p>Conclusions</p> <p>The vast knowledge base of clinical practice makes full preparation impossible. Our statement about feeling prepared is simple yet discriminating and identified some substantial differences between medical schools. Medical schools need feedback from graduates about elements of training that could be improved.</p

Medical graduates’ preparedness to practice: A comparison of undergraduate medical school training

Background: There is evidence that newly qualified doctors do not feel prepared to start work. This study examined views of first year Foundation doctors (F1s) regarding how prepared they felt by their undergraduate medical education for skills required during the first Foundation training year in relation to their type of training. Method: One-hundred and eighty two F1s completed a questionnaire during their first rotation of Foundation training. Analysis was conducted by type of medical school training: Problem-Based Learning (PBL), Traditional or Reformed. Results: F1s from medical schools with a PBL curriculum felt better prepared for tasks associated with communication and team working, and paperwork than graduates from the other medical school types; but the majority of F1s from all three groups felt well prepared for most areas of practice. Less than half of graduates in all three groups felt well prepared to deal with a patient with neurological/visual problems; write referral letters; understand drug interactions; manage pain; and cope with uncertainty. F1s also indicated that lack of induction or support on starting work was affecting their ability to work in some areas. Conclusions: Whilst F1s from medical schools with a PBL curriculum did feel better prepared in multiple areas compared to graduates from the other medical school types, specific areas of unpreparedness related to undergraduate and postgraduate medical training were identified across all F1s. These areas need attention to ensure F1s are optimally prepared for starting work

Structure of a bacterial cell surface decaheme electron conduit

Some bacterial species are able to utilize extracellular mineral forms of iron and manganese as respiratory electron acceptors. In Shewanella oneidensis this involves decaheme cytochromes that are located on the bacterial cell surface at the termini of trans-outer-membrane electron transfer conduits. The cell surface cytochromes can potentially play multiple roles in mediating electron transfer directly to insoluble electron sinks, catalyzing electron exchange with flavin electron shuttles or participating in extracellular intercytochrome electron exchange along “nanowire” appendages. We present a 3.2-Å crystal structure of one of these decaheme cytochromes, MtrF, that allows the spatial organization of the 10 hemes to be visualized for the first time. The hemes are organized across four domains in a unique crossed conformation, in which a staggered 65-Å octaheme chain transects the length of the protein and is bisected by a planar 45-Å tetraheme chain that connects two extended Greek key split ß-barrel domains. The structure provides molecular insight into how reduction of insoluble substrate (e.g., minerals), soluble substrates (e.g., flavins), and cytochrome redox partners might be possible in tandem at different termini of a trifurcated electron transport chain on the cell surface