2,969 research outputs found
Drag forces at the ice-sheet bed and resistance of hard-rock obstacles: the physics of glacial ripping
No full textGlacial ripping involves glaciotectonic disintegration of rock hills and extensive removal of rock at the ice-sheet bed, triggered by hydraulic jacking caused by fluctuating water pressures. Evidence from eastern Sweden shows that glacial ripping caused significant subglacial erosion during the final deglaciation of the Fennoscandian ice sheet, distinct from abrasion and plucking (quarrying). Here we analyse the ice drag forces exerted onto rock obstacles at the base of an ice sheet, and the resisting forces of such rock obstacles: glaciotectonic disintegration requires that ice drag forces exceed the resisting forces of the rock obstacle. We consider rock obstacles of different sizes, shapes and fracture patterns, informed by natural examples from eastern Sweden. Our analysis shows that limited overpressure events, unfavourable fracture patterns, low-transmissivity fractures, slow ice and streamlined rock hamper rock hill disintegration. Conversely, under fast ice flow and fluctuating water pressures, disintegration is possible if the rock hill contains subhorizontal, transmissive fractures. Rock steps on previously smooth, abraded surfaces, caused by hydraulic jacking, also enhance drag forces and can cause disintegration of a rock hill. Glacial ripping is a physically plausible erosion mechanism, under realistic glaciological conditions prevalent near ice margins
Juvenile problem/needs analysis : Oregon
No full textsubmitted to: Youth Development Division, Oregon Department of Education ; submitted by: Adrian J. Johnson, M.S.W. Lisa M. Lucas, B. A. Juliette R. Mackin, Ph.D.Title from PDF cover (viewed on February 1, 2023).This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Mode of access: Internet from the Oregon Government Publications Collection.Text in English
G 2(2) as the automorphism group of the octonionic root system of E 7
No full textKarsch F, Koca M. G 2(2) as the automorphism group of the octonionic root system of E 7. Journal of Physics, A: Mathematical and General. 1990;23(21):4739-4750.A simple method is suggested for the construction of the seven-dimensional representation of the adjoint Chevalley group G 2(2), the automorphism group of the octonionic root system of E 7. The maximal subgroups of G 2(2) preserving the octonionic root systems of the maximal subgroups of E 7 are identified. Possible implications in physics are discussed
Retracted article: Students' learning styles and academic performance in Readings in Philippine History: Basis for a proposed course syllabus enhancement
No full textThe article entitled “Students’ learning styles and academic performance in Readings in Philippine History: Basis for a proposed course syllabus enhancement” (Volume 4, Issue 1, December 2022, pp. 45-51) written by Adrian Ote, Margie M. Lepangge, Nobelen Joy M. Marsonia, Sheena Joy C. Pagran, Jennilyn C. Se, and Jason A. Romero has been retracted at the request of the Corresponding Author
Extractive Reserves: Building Natural Assets in the Brazilian Amazon
No full textIn the Amazon rainforest, Brazil's rubber tappers were the first social group to challenge the predatory development model that is threatening ecological disaster there. Their strategy to set up “extractive reserves”—conservation areas where the local population can harvest non-timber forest products—is examined in “Extractive Reserves: Building Natural Assets in the Brazilian Amazon,” by Anthony Hall.
Transcriptomic and proteomic response of the organohalide respiring bacterium Desulfoluna spongiiphila to growth with 2,6-dibromophenol as electron acceptor
No full textPeer reviewe
Approaches to uncertain or imprecise rules: a survey
No full textWith this paper we present a brief overview of selected prominent approaches to rule frameworks and formal rule languages for the representation of and reasoning with uncertain or imprecise knowledge. This work covers selected probabilistic and possibilistic logics, as well as implementations of uncertainty and possibilistic reasoning in rule engine software
Trapping of Hot Carriers in the Forksheet FET Wall: A TCAD Study
No full textsponsorship: The work of M. Vandemaele was supported by the Ph.D. Fellowship of the Research Foundation Flanders (Belgium) under Grant 11A3621N. The review of this letter was arranged by Editor S. Hall. (Corresponding author: M. Vandemaele.) (Research Foundation Flanders (Belgium)|11A3621N)status: Publishe
Past and future impact of glacial erosion in Forsmark and Uppland : final report
No full textThe following report constitutes a final report of a comprehensive study on denudation and glacial
erosion conducted at Forsmark and in the surrounding Uppland province, Sweden, between 2015 and
2019. The aim was to quantify the amount of past denudation at the Forsmark site and the broader
Uppland region, with special focus on glacial erosion, by employing a range of methodologies. The
methods included geomorphological mapping and analysis of the bedrock surface and Quaternary
deposits, cosmogenic exposure dating, bedrock fracture mapping, and shallow bedrock stress modelling.
The results were also used together with results from a long-term climate modelling study to
quantify the potential amount of glacial erosion at Forsmark over the coming one million years.
The study was initiated by Jens-Ove Näslund (SKB) and it was jointly designed by Jens-Ove Näslund,
Adrian Hall (Stockholm University), Karin Ebert (Södertörn University), Bradley Goodfellow
(Stockholm University, SGU), Clas Hättestrand (Stockholm University), Jakob Heyman (University
of Gothenburg) and Arjen Stroeven (Stockholm University). Adrian Hall coordinated the scientific
work within the study, and also conducted the studies on long-term burial and erosion history
(Chapter 2) and glacial erosion (Chapter 4). Karin Ebert developed the digital elevation models of
the unconformity and derived the glacial erosion estimates derived from summit erosion surfaces.
Bradley Goodfellow contributed across the project and conducted the study of topographic stress
perturbation, with mathematical modelling by Seulgi Moon (University of California, Los Angeles)
(Chapter 3). Clas Hättestrand developed geomorphological maps of the unconformity and of glacial
bedforms. Maarten Krabbendam (British Geological Survey) contributed to Chapter 2 on the longterm
burial and erosion history and to Chapter 4 on glacial erosion and mapped landforms associated
with glacial ripping in Uppland. Sample site selection and cosmogenic nuclide sample collection was
carried out by Jakob Heyman, Bradley Goodfellow, Arjen Stroeven, Marc Caffee and Adrian Hall.
Jakob Heyman conducted the modelling of cosmogenic nuclide erosion and burial histories. Bradley
Goodfellow was involved in cosmogenic nuclide sample preparation at Purdue University. Reporting
and interpretation of cosmogenic nuclide results in Chapter 5 was done by Jakob Heyman, Arjen
Stroeven and Bradley Goodfellow. All authors contributed to the final revision of the report.
The study includes several additional important contributions. Marc Caffee (Purdue University) was
responsible for all cosmogenic isotope laboratory analyses and guided and participated in the discussions
of interpretation of results (Chapter 5). Stephen Martel (University of Hawaii) and Taylor
Perron (Massachusetts Institute of Technology) were involved in the fracture mapping and modelling
(Chapter 3). Mikis van Boeckel (Stockholm University) produced many of the figures in the report
from digital elevation model data from the Swedish mapping, cadastral and land registration authority
(Lantmäteriet) and SGU.
In connection to the present study, two additional studies have been performed employing similar
methods (e.g. geomorphological analysis and cosmogenic exposure dating) for studying the sub-
Cambrian unconformity in the Trollhättan area in south-western Sweden. The two associated studies
will be published in separate reports (Goodfellow et al. 2019, Hall et al. 2019a).
The results will be used, together with other published scientific information, for constructing future
scenarios of climate and climate-related processes in SKB’s work on assessing long-term safety of
nuclear waste repositories in Sweden. The safety assessments performed for the planned repository
for spent nuclear fuel in Forsmark, Sweden, cover a total time span of one million years. Since this
time span covers the timescales relevant for glacial cycles, the effect of future glacial erosion needs
to be analysed in the safety assessments. In this context, the present study provides important results
on the potential amount of glacial erosion that may be expected in the topographical, geological, and
glaciological setting of the Forsmark site. A separate study models changes in climate over the next
1 million years and has been published ahead of this report (Lord et al. 2019)
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