3,230 research outputs found
Emergence of the Shackleton Range from beneath the Antarctic Ice Sheet due to glacial erosion
This paper explores the long-term evolution of a subglacial fjord landscape in the Shackleton Range, Antarctica. We propose that prolonged ice-sheet erosion across a passive continental margin caused troughs to deepen and lower the surrounding ice-sheet surface, leaving adjacent mountains exposed. Geomorphological evidence suggests a change in the direction of regional ice flow accompanied emergence. Simple calculations suggest that isostatic compensation caused by the deepening of bounding ice-stream troughs lowered the ice-sheet surface relative to the mountains by ~800m. Use of multiple cosmogenic isotopes on bedrock and erratics (26Al, 10Be, 21Ne) provides evidence that overriding of the massif and the deepening of the adjacent troughs occurred earlier than the Quaternary. Perhaps this occurred in the mid-Miocene, as elsewhere in East Antarctica in the McMurdo Dry Valleys and the Lambert basin. The implication is that glacial erosion instigates feedback that can change ice-sheet thickness, extent, and direction of flow. Indeed, as the subglacial troughs evolve over millions of years, they increase topographic relief; and this changes the dynamics of the ice sheet. © 2013 Elsevier B.V
Women in radiology: gender diversity is not a metric-it is a tool for excellence.
Women in Focus: Be Inspired was a unique programme held at the 2019 European Congress of Radiology that was structured to address a range of topics related to gender and healthcare, including leadership, mentoring and the generational progression of women in medicine. In most countries, women constitute substantially fewer than half of radiologists in academia or private practice despite frequently accounting for at least half of medical school enrolees. Furthermore, the proportion of women decreases at higher academic ranks and levels of leadership, a phenomenon which has been referred to as a "leaky pipeline". Gender diversity in the radiologic workplace, including in academic and leadership positions, is important for the present and future success of the field. It is a tool for excellence that helps to optimize patient care and research; moreover, it is essential to overcome the current shortage of radiologists. This article reviews the current state of gender diversity in academic and leadership positions in radiology internationally and explores a wide range of potential reasons for gender disparities, including the lack of role models and mentorship, unconscious bias and generational changes in attitudes about the desirability of leadership positions. Strategies for both individuals and institutions to proactively increase the representation of women in academic and leadership positions are suggested. KEY POINTS: • Gender-diverse teams perform better. Thus, gender diversity throughout the radiologic workplace, including in leadership positions, is important for the current and future success of the field. • Though women now make up roughly half of medical students, they remain underrepresented among radiology trainees, faculty and leaders. • Factors leading to the gender gap in academia and leadership positions in Radiology include a lack of role models and mentors, unconscious biases, other societal barriers and generational changes
2-Axis Electric Off-Road Bucket Seat Bases
Off-road vehicle bucket seats are currently restricted to a single position relative to the floor of the vehicle. Drivers and riders desire the ability to adjust their seat position to increase comfort and allow for a greater size range of riders to fit safely within the cabin or roll cage. To develop a viable solution, the team has gone through an extensive design process and has constructed a functioning prototype. This Final Design Report encapsulates the entire design process and concludes with recommendations for changes we would make looking both back in review as well as moving forward with further iterations of the product
10Be in Ice Cores and 14C in Tree Rings: Separation of Production and Climate Effects
Cosmogenic radionuclides are more and more used in solar activity reconstructions. However, the cosmogenic radionuclide signal also contains a climate component. It is therefore crucial to eliminate the climate information to allow a better interpretation of the reconstructed solar activity indices. In this paper the method of principal components is applied to 10Be data from two ice cores from opposite hemispheres as well as to 14C data from tree rings. The analysis shows that these records are dominated by a common signal which explains about 80% of the variance on multi decadal to multi millennial time scales, reflecting their common production rate. The second and third components are significantly different for 14C and 10Be. They are interpreted as system effects introduced by the transport of 10Be and 14C from the atmosphere where they are produced to the respective natural archives where they are stored. Principal component analysis improves significantly extraction of the production signal from the cosmogenic isotope data series, which is more appropriate for astrophysical and terrestrial studie
Early last glacial maximum in the southern Central Andes reveals northward shift of the westerlies at ~39 ka
The latitudinal position of the southern westerlies has been suggested to be a key parameter for the climate on Earth. According to the general notion, the southern westerlies were shifted equatorward during the global Last Glacial Maximum (LGM: ~24–18 ka), resulting in reduced deep ocean ventilation, accumulation of old dissolved carbon, and low atmospheric CO<sub>2</sub> concentrations. In order to test this notion, we applied surface exposure dating on moraines in the southern Central Andes, where glacial mass balances are particularly sensitive to changes in precipitation, i.e. to the latitudinal position of the westerlies. Our results provide robust evidence that the maximum glaciation occurred already at ~39 ka, significantly predating the global LGM. This questions the role of the westerlies for atmospheric CO<sub>2</sub>, and it highlights our limited understanding of the forcings of atmospheric circulation
Application of the coupling model to magnetic after effects in the Fe72Co10Nb6B12 amorphous alloy
It was shown that magnetic reluctivity measured versus time after demagnetization for pre-annealed samples
of the Fe72Co10Nb6B12 amorphous alloy exhibits highly non-exponential behavior which can be described by
the coupling model. The relaxation intensity and the coupling parameter describing correlation effects in free
volume diffusion decrease with increasing 1 h annealing temperature indicating annealing out of free volume and
formation of iron clusters in amorphous matrix
Impact of Energy Crops on Soil Management and Erosion
Energy crops are perennials that require less cultivation and inputs than conventional crops, and are low maintenance harvest crops used for biofuels
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