2,953 research outputs found
The impact of future sea-level rise on the European Shelf tides
No full textThis paper investigates the effect of future sea-level rise (SLR) on the tides of the northwest European Continental Shelf. The European shelf tide is dominated by semidiurnal constituents. This study therefore focuses primarily on the changes in the M2 tidal constituent and the spring and neap tidal conditions. The validated operational Dutch Continental Shelf Model is run for the present day sea-level as well as 2 and 10 m SLR scenarios.
The M2 tidal amplitude responds to SLR in a spatially non-uniform manner, with substantial amplitude increases and decreases in both scenarios. The M2 tidal response is non-linear between 2 and 10 m with respect to SLR, particularly in the North Sea. Under the 2 m SLR scenario the M2 constituent is particularly responsive in the resonant areas of the Bristol Channel and Gulf of St. Malo (with large amplitude decreases) and in the southeastern German Bight and Dutch Wadden Sea (with large amplitude increases). Changes in the spring tide are generally greater still than those in the M2 or neap tides. With 2 m SLR the spring tidal range increases up to 35 cm at Cuxhaven and decreases up to −49 cm at St. Malo. Additionally the changes in the shallow water tides are larger than expected. With SLR the depth, wave speed and wave length (tidal resonance characteristics) are increased causing changes in near resonant areas. In expansive shallow areas SLR causes reduced energy dissipation by bottom friction. Combined these mechanisms result in the migration of the amphidromes and complex patterns of non-linear change in the tide with SLR.
Despite the significant uncertainty associated with the rate of SLR over the next century, substantial alterations to tidal characteristics can be expected under a high end SLR scenario. Contrary to existing studies this paper highlights the importance of considering the modification of the tides by future SLR. These substantial future changes in the tides could have wide reaching implications; including for example, correctly calculating design level requirements for flood defences, the availability of tidal renewable energy and dredging requirements
Impacts of hunter-gatherers on the vegetation history of the eastern vale of pickering, Yorkshire
No full textResearch is undertaken into the vegetation and human impact at three previously un-researched archaeological sites from the eastern Vale of Pickering. The vegetation history is reconstructed from the end of the Windermere Interstadial c. 13,000 (^14)C yr BP until the final Mesolithic c. 5100 (^14)C yr BP. The early Mesolithic human impact on the vegetation is assessed using a three stage statistical test to establish the internal variability in the data as well as background variations in pollen output. The results reveal that humans had a small but significant impact on the vegetation around two of the sites. Pollen preservation at the third site precluded analyses of the impacts of humans on the vegetation. The three-stage test used to test for human impact was quite successful but requires revision before any further use. On the whole the tests confirmed the findings of conventional human impact analyses. During the pre-Holocene fires occurred on a regular basis. These fires varied in location and intensity, suggesting that some of the fires were regional or large-scale, whilst others were small and very localized. A multi-causal explanation has been given for the fires. Later, during the early Mesolithic, human groups are thought to have burnt the reedswamp at the lake edges as part of an economic strategy. Star Carr is the only site that demonstrates clearance of significant areas of woodland. During the later Mesolithic the hunter-gatherers have a greater impact on the vegetation within the Vale. This is attributed to the need for more resources as a result of vegetation change and increased population levels. Unlike their counter-parts from the North York Moors, the occupants of the lowland Vale of Pickering cause no long-term change to their environment
Sampling power-law distributions
No full textPower-law distributions describe many phenomena related to rock fracture. Data collected to measure the parameters of such distributions only represent samples from some underlying population. Without proper consideration of the scale and size limitations of such data, estimates of the population parameters, particularly the exponent D, are likely to be biased. A Monte Carlo simulation of the sampling and analysis process has been made, to test the accuracy of the most common methods of analysis and to quantify the confidence interval for D. The cumulative graph is almost always biased by the scale limitations of the data and can appear non-linear, even when the sample is ideally power law. An iterative correction procedure is outlined which is generally successful in giving unbiased estimates of D. A standard discrete frequency graph has been found to be highly inaccurate, and its use is not recommended. The methods normally used for earthquake magnitudes, such as a discrete frequency graph of logs of values and various maximum likelihood formulations can be used for other types of data, and with care accurate results are possible. Empirical equations are given for the confidence limits on estimates of D, as a function of sample size, the scale range of the data and the method of analysis used. The predictions of the simulations are found to match the results from real sample D-value distributions. The application of the analysis techniques is illustrated with data examples from earthquake and fault population studies
Possible new evidence for Mid-Pleistocene glaciation in the Vale of Pickering, North Yorkshire, UK
No full textWhilst the Late Devensian glaciation (MIS2) of the Vale of Pickering is well-documented, earlier glaciations within it are not. A proposed limited glaciation in the Mid-Pleistocene, thought to be of Marine Isotope Stage 8 (MIS) age is not well constrained. This paper aims to obtain preliminary ages for two of the most prominent geomorphic features in the Vale of Pickering to see if they related to pre-Devensian glaciations. New luminescence dating by infra-red stimulation of feldspars from sand accumulations near the summit of Gallows Hill, part of the Wykeham Moraine, and from a section through poorly sorted fluvial sand and gravel on the flanks of the Hutton Buscel Terrace in Yedman Dale gave ages of 176 ± 14 ka and 156 ± 12 ka, respectively. Evidence suggests they represent a glacial incursion (MIS 6) into the Vale of Pickering blocking its eastern end and forming a pre-Devensian Glacial Lake Pickering. Whilst they could be older, this style of glaciation is very different to the limited plateau ice-field proposed for MIS 8 at the western end of the Vale of Pickering. Taken at face value, these preliminary ages suggest that the Vale of Pickering was partially glaciated in MIS 6 as part of a wider ice sheet and contemporary with the Saalian glaciation in Europe
George McClellan [1849-1913]: A Memoir read before the College of Physicians of Philadelphia, by J. Chalmers Da Costa, M.D., LL.D., Samuel D. Gross Professor of Surgery in Jefferson Medical College
No full textA memoir of Dr. George McClellan (1849-1913). Dr. McClellan was the author of the book Regional Anatomy, and grandson of George McClellan, M.D.; the founder of Jefferson Medical College
2000 Commencement Address: G. Timothy Johnson, M.D.
No full textTimothy Johnson, M.D., medical editor for ABC News will deliver the principal address and receive an honorary degree at the 154th commencement exercises at the College of the Holy Cross on Friday, May 26, beginning at 10:30 a.m. at Fitton Field.
Johnson, one of the nation’s leading medical communicators of health care information, has provided commentary on medical problems and answers for viewers since 1975. In addition to commentary on Good Morning America, Johnson provides on-air analysis of medical news for World News Tonight, Nightline and 20/20. He consults with ABC News regardingcoverage of medical news. He is also medical editor for WCVB-TV, Channel 5 in Boston.
Johnson holds joint positions in medicine at Harvard University and Massachusetts General Hospital in Boston. He is the founding editor of the Harvard Medical School Health Letter and co-editor of the Harvard Medical School Health Letter Book. He is also coeditor of the book, “Your Good Health,” published by Harvard Press, as well as co-author with former US Surgeon General Dr. C. Everett Koop of the book, “Let’s Talk,” published by Zondervan in 1992.
He originally intended to join the ministry and graduated from the North Park Seminary in 1963. Two years later he decided to enter medicine. Johnson, who is a Phi Beta Kappa graduate of Augustana College, graduated summa cum laude from Albany Medical College and holds a master’s degree in public health from Harvard University. Johnson served as an assisting minister at the Community Covenant Church in West Peabody, Mass.https://crossworks.holycross.edu/commence_address/1012/thumbnail.jp
Interview with Robert Campbell, M.D.
No full textRobert A. Campbell, M.D., talks about his military service in the Navy during World War II, his undergraduate and medical education afterward, his residency in pediatrics, and how he came to the University of Oregon Medical School in 1961. He gives a lengthy report of events during his early years under Dr. Donald Pickering, the director of the newly formed Oregon Regional Primate Research Center. He talks about his years in the Department of Pediatrics, the department's relations with Crippled Children's Division and Doernbecher Memorial Hospital for Children, his fundraising, his work in the kidney transplant program, and his own research on polyamines. Campbell also discusses the dehumanizing effect of technological advances in bedside care and what he sees in the future of medicine
Robust energy transfer mechanism via precession resonance in nonlinear turbulent wave systems
No full textA robust energy transfer mechanism is found in nonlinear wave systems, which favours transfers towards modes interacting via triads with nonzero frequency mismatch, applicable in meteorology, nonlinear optics and plasma wave turbulence. We emphasise the concepts of truly dynamical degrees of freedom and triad precession. Transfer efficiency is maximal when the triads' precession frequencies resonate with the system's nonlinear frequencies, leading to a collective state of synchronised triads with strong turbulent cascades at intermediate nonlinearity. Numerical simulations confirm analytical predictions
SOME SOCIAL AND POLITICAL VIEWS M.D. SKOBELEVS
No full textThe article analyzes social and political views of M.D. Skobelev, an outstanding military commander, a hero of the Russian-Turkish and Balkan wars¸ who contributed greatly to the entry of Central Asia (Turkestan) and other regions into the Russian Empire. The author concludes that M.D. Skobelev’s views were close to those of the Slavophiles, though they differed greatly on a number of key issues. They both considered that it was necessary to restore national identity, to consolidate Orthodoxy, to give up European values to the detriment of national ones, to search for the own development way instead of the western one, which was deadlock and destructive
The impact of future sea-level rise on the global tides
No full textTides are a key component in coastal extreme water levels. Possible changes in the tides caused by mean sea-level rise (SLR) are therefore of importance in the analysis of coastal flooding, as well as many other applications. We investigate the effect of future SLR on the tides globally using a fully global forward tidal model: OTISmpi. Statistical comparisons of the modelled and observed tidal solutions demonstrate the skill of the refined model setup with no reliance on data assimilation. We simulate the response of the four primary tidal constituents to various SLR scenarios. Particular attention is paid to future changes at the largest 136 coastal cities, where changes in water level would have the greatest impact.Spatially uniform SLR scenarios ranging from 0.5 to 10 m with fixed coastlines show that the tidal amplitudes in shelf seas globally respond strongly to SLR with spatially coherent areas of increase and decrease. Changes in the M2 and S2 constituents occur globally in most shelf seas, whereas changes in K1 and O1 are confined to Asian shelves. With higher SLR tidal changes are often not proportional to the SLR imposed and larger portions of mean high water (MHW) changes are above proportional. Changes in MHW exceed ±10% of the SLR at ~10% of coastal cities. SLR scenarios allowing for coastal recession tend increasingly to result in a reduction in tidal range. The fact that the fixed and recession shoreline scenarios result mainly in changes of opposing sign is explained by the effect of the perturbations on the natural period of oscillation of the basin. Our results suggest that coastal management strategies could influence the sign of the tidal amplitude change. The effect of a spatially varying SLR, in this case fingerprints of the initial elastic response to ice mass loss, modestly alters the tidal response with the largest differences at high latitudes
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