2,313 research outputs found

    Relationships of Soil Acidity and Air Temperature to the Wind and Vegetation at Prudhoe Bay, Alaska

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    Investigations in the Prudhoe Bay vicinity suggest that prevailing winds from the east combined with the shape of the coastline and a source of calcareous materials in the Sagavanirktok River delta cause distinct patterns of soil reaction and temperature. Areas downwind from the river have basic soil pH values ranging from 7.1 to 8.4, whereas wet tundra sites outside the path of loess-laden winds have acidic values ranging from 5.3 to 7.0. The winds also affect the local climate by blowing moist cold air and fog further inland in the western part of the Prudhoe Bay oil field. Air temperatures are correlated with distance to the ocean measured in the direction of the prevailing wind vector. The temperature differences also influence the depth of the active layer. The differences in pH and temperatures affect the vegetation of the region. The areas with basic soils show relative abundance of calciphiles, whereas areas with lower pH values have acidophilous plants. Lower temperatures near the coast affect the distribution of many taxa as well as the phenology and stature of the vegetation

    Combining Research and Education: Bioclimatic Zonation along a Canadian Arctic Transect

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    Scientists and students from five countries combined research and education in an investigation of bioclimatic zonation along a Canadian Arctic transect, from Amund Ringnes Island and Ellesmere Island in the north to the Daring Lake research camp at the southern edge of the tundra in Nunavut. We addressed three important needs in Arctic science: 1) to integrate education and research, 2) to provide field experiences for undergraduates, and 3) to foster international collaboration. We describe five subzones within the Arctic tundra zone. Subzones are defined by the vegetation typical of mesic environments at low elevations and the dominant growth forms of vegetation in these environments. Subzonal boundaries coincide with the northern limits of several species of woody plants with distinct upright or prostrate growth forms, and ultimately with the northern limit of woody plant species. The five subzones, A-E, from north to south, are characterized by dominant growth form: (A) cushion forb, (B) prostrate dwarf shrub, (C) hemiprostrate dwarf shrub, (D) erect dwarf shrub, and (E) low shrub.Des chercheurs et des étudiants de cinq pays ont combiné recherche et éducation dans une étude portant sur la zonation bioclimatique le long d'un transect de l'Arctique canadien, allant de l'île Amund Ringnes et de l'île d'Ellesmere au nord, au camp de recherche du lac Daring situé en bordure sud de la toundra au Nunavut (Canada). On a tenu compte de trois besoins majeurs dans la science de l'Arctique, soit ceux: 1) d'intégrer l'éducation et la recherche; 2) d'offrir aux étudiants de premier cycle des expériences sur le terrain, et 3) de promouvoir la collaboration internationale. On décrit cinq sous-zones à l'intérieur de la zone de toundra de l'Arctique. Les sous-zones sont définies par la végétation typique des milieux à régime d'humidité constant à basse altitude ainsi que par la forme de croissance dominante dans ces habitats. Les limites des sous-zones correspondent aux limites septentrionales de plusieurs espèces de plantes ligneuses ayant des formes de croissance particulières verticales ou procombantes, et en fin de compte à la limite septentrionale des espèces de plantes ligneuses. Les cinq sous-zones (A-E), établies du nord au sud, sont caractérisées par une forme de croissance dominante: A) herbe non graminéenne en coussinet; B) arbuste nain déprimé; C) arbuste nain semi-déprimé; D) arbuste nain dressé, et E) arbuste

    Data on the number and frequency of scientific literature citations for established medulloblastoma cell lines

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    This article collates information about the number of scientific articles mentioning each of the established medulloblastoma cell lines, derived through a systematic search of Web of Science, Scopus and Google Scholar in 2016. The data for each cell line have been presented as raw number of citations, percentage share of the total citations for each search engine and as an average percentage between the three search engines. In order to correct for the time since each cell line has been in use, the raw citation data have also been divided by the number of years since the derivation of each cell line. This is a supporting article for a review of in vitro models of medulloblastoma published in “in vitro models of medulloblastoma: choosing the right tool for the job” (D.P. Ivanov, D.A. Walker, B. Coyle, A.M. Grabowska, 2016) [1]

    Effects of Crude and Diesel Oil Spills on Plant Communities at Prudhoe Bay, Alaska, and the Derivation of Oil Spill Sensitivity Maps

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    Crude oil was spilled on six of the major Prudhoe Bay plant communities at an intensity of 12 l/m². The communities occurred along a topographic-moisture gradient. The reaction of the major species of the various communities was recorded one year following the spills. Sedges and willows showed substantial recovery from crude oil spills. Mosses, lichens, and most dicotyledons showed little or no recovery. On a very wet plot with standing water, the vegetation showed total recovery one year following the spill. Dry plots, on the other hand, showed very poor recovery. Dryas integrifolia M. Vahl, the most important vascular species on dry sites, was killed. Identical experiments using diesel oil rather than crude oil showed all species except an aquatic moss to be killed. A sensitivity index for the communities was calculated on the basis of the percentage cover of the resistant species divided by the original total plant cover of the community. With this information an oil spill sensitivity map for an area of Prudhoe Bay was constructed using a vegetation map as a base. Using the crude oil data from Prudhoe Bay together with some from the literature, a predictive sensitivity map was also constructed for an accidental crude oil spill at nearby Franklin Bluffs. In this example all the community types are considered to have moderate to excellent recovery potential. Implications of the experiments and the mapping exercises for oil spill contingency planning are discussed

    Extension parallel to the rift zone during segmented fault growth: application to the evolution of the NE Atlantic

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    The mechanical interaction of propagating normal faults is known to influence the linkage geometry of first-order faults, and the development of second-order faults and fractures, which transfer displacement within relay zones. Here we use natural examples of growth faults from two active volcanic rift zones (Koa`e, island of Hawai`i, and Krafla, northern Iceland) to illustrate the importance of horizontal-plane extension (heave) gradients, and associated vertical axis rotations, in evolving continental rift systems. Second-order extension and extensional-shear faults within the relay zones variably resolve components of regional extension, and components of extension and/or shortening parallel to the rift zone, to accommodate the inherently three-dimensional (3-D) strains associated with relay zone development and rotation. Such a configuration involves volume increase, which is accommodated at the surface by open fractures; in the subsurface this may be accommodated by veins or dikes oriented obliquely and normal to the rift axis. To consider the scalability of the effects of relay zone rotations, we compare the geometry and kinematics of fault and fracture sets in the Koa`e and Krafla rift zones with data from exhumed contemporaneous fault and dike systems developed within a > 5×104 km2 relay system that developed during formation of the NE Atlantic margins. Based on the findings presented here we propose a new conceptual model for the evolution of segmented continental rift basins on the NE Atlantic margins

    Development and Assessment of a Patient-Centered Care Curriculum

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    The purpose of this paper is to chronicle the development and implementation of a pilot offering of the patient-centered care (PCC) curriculum sponsored by a partnership of schools of allied health and nursing and a local health care system. The objective of this interdisciplinary track is to increase the competency of allied health and nursing graduates to function in health care teams in both PCC and non-PCC hospital environments, thus improving the effectiveness of patient care. The elective track consists of two courses; a third course is under consideration. Students and faculty participating in the elective track were surveyed to assess their attitudes toward change and patient-centered care. Generally, participants believed that they could work well together but were not convinced of the viability of the PCC. Although the curriculum is still in its implementation stage and the nursing participation became minimal, this study aids in understanding opinions of nursing and allied health faculty and students regarding a new PCC curriculum

    Quasi-particle Lifetimes in a d_{x^2-y^2} Superconductor

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    We consider the lifetime of quasi-particles in a d-wave superconductor due to scattering from antiferromagnetic spin-fluctuations, and explicitly separate the contribution from Umklapp processes which determines the electrical conductivity. Results for the temperature dependence of the total scattering rate and the Umklapp scattering rate are compared with relaxation rates obtained from thermal and microwave conductivity measurements, respectively.Comment: 14 pages, 4 figure

    Culture of surfclams Spisula solidissima sp., in coastal Georgia: nursery culture

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    Peer-reviewedGrowth of the Atlantic surfclam, Spisula solidissima solidissima, was compared with that of the southern Atlantic surfclam, Spisula solidissima similis. All experimental animals were reared in upweller units at 20°C and fed cultured algae on a daily basis. Over the 14 wk of the study, the Atlantic surf clams grew markedly better (8.9-mm increase in shell length and a 1,103% increase in biomass) than the southern Atlantic surfclams (6.6-mm increase in shell length and 573% mcrease in biomass). Mortality for both groups was negligible. The mean shell lengths attained for the Atlantic surfclams (15.3 mm) and the southern Atlantic surfclams (13 mm) at the conclusion of the study were large enough to ensure good growth and survival on relocation to a field growout environment. The growth patterns obtained under similm growth conditions further highlight some basic life history differences between these subspecies, which were apparent from other studies
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