Foot function and normal coronal plane range-of-motion at the ankle-joint-complex

An investigation was carried out into normal coronal plane range-of-motion at the ankle-joint-complex. To facilitate this, an accurate and reliable measurement rig was designed. The range of motion at the ankle joint complex was measured in one hundred subjects of both sexes (mean age 24.6, range 18-49) by applying a torque of 4Nm to an axis which deviated medially by 16 degrees. The results showed a mean equilibrium position of 19.5 degrees inverted, a mean total range of motion from the equilibrium position of 66.15 degrees, and a mean total inversion value from horizontal of 64.4 degrees. Three further experiments were carried out. The purpose of these was to examine diurnal variation in range of motion (n = 7), to examine the effect of rig axis position on the range of motion (n = 15), and to look for any difference in ankle joint complex range of motion in those patients with symptoms proximal to the ankle, and those with symptoms distal to the ankle (n = 20). Significant differences in measurement for each variable at each time interval for all subjects were observed, and significant differences in range of motion were found for each measurement, apart from inversion, when movement around different axis orientations were compared. Similar inversion values are due to the difference m equilibrium position between an axis bisecting the foot and an axis which deviates by 16 degrees medially, and a comparison of inversion values from horizontal show a mean difference of 27 degrees. No significant difference m range of motion was found in a comparison study of patients with symptoms distal and proximal to the ankle joint complex. The findings of this study have important implications both for clinical practice in the field of foot and ankle treatment, and for further research into ranges of motion at the ankle joint complex

Influences on Consumers\u27 Recycling Intentions of Compact Fluorescent Lamps—Mercury as a Factor

The purpose of the current study is to understand consumers’ behavioral intentions in situations involving both positive and negative potential impacts on the environment. The case of energy efficient Compact Fluorescent Lamps (CFLs) with their potential for mercury pollution is an example of this type of trade-off. Past studies have confirmed the usefulness of the Theory of Reasoned Action for identifying the antecedents influencing recycling rates, however, none have looked at situations where conflicting environmental trade-offs were involved. Stepwise regression analysis was used to develop a core model which explains R2=.561 of the intention to recycle. Significant antecedents include the peer group subjective norm of recycling CFLs (Beta=.661), the attitude towards recycling of CFLs (Beta=.417), the attitude towards the overall environmental friendliness of CFLs (Beta=-.344), and the attitude towards the number of sites available for recycling of CFLs (Beta=.212). Adding the impact of past recycling behavior increases the model’s explanatory power to .726. Important policy implications result from the finding that the number of people who would ‘always or usually’ recycle CFLs increased to 90% by enhancing the convenience of recycling. A significant managerial implication results from the contradictory findings that the attitude towards mercury is not significantly correlated with intentions to recycle, however the attitude towards the environmental friendliness of CFLs was negatively related to recycling intentions. This potentially indicates that there is a lack of understanding of the net positive impact of CFLs and there is potential confusion about the related environmental trade-offs. Recommendations for policy and marketing responses are suggested

Oceanic Boundary Conditions for Jakobshavn Glacier. Part II: Provenance and Sources of Variability of Disko Bay and Ilulissat Icefjord Waters, 1990–2011

Jakobshavn Glacier, west Greenland, has responded to temperature changes in Ilulissat Icefjord, into which it terminates. Basin waters in this fjord exchange with neighboring Disko Bay waters of a particular density at least once per year. This study determined the provenance of this isopycnic layer for 1990–2011 using hydrographic data from Cape Farewell to Baffin Bay. The warm Atlantic-origin core of the West Greenland Current never filled deep Disko Bay or entered the fjord basin because of bathymetric impediments on the west Greenland shelf. Instead, equal parts of Atlantic water and less-saline polar water filled the fjord basin and bathed Jakobshavn Glacier. The polar water fraction was often traceable to the East/West Greenland Current but sometimes to the colder Baffin Current. The huge annual temperature cycle on West Greenland Current isopycnals did not propagate into deep Disko Bay or the fjord basin because isopycnals over the west Greenland shelf were depressed during the warm autumn/winter phase of the cycle. Ilulissat Icefjord basin waters were anomalously cool in summer 2010. This was not because of the record low NAO index winter of 2009/10 or atmospheric anomalies over Baffin Bay but, possibly, because of high freshwater flux through the Canadian Arctic and a weak West Greenland Current in early 2010. Together, this caused cold Baffin Current water to flood the west Greenland shelf. Subpolar gyre warming associated with the NAO anomaly in winter 2009/10 was more likely responsible for the record warm Disko Bay and Ilulissat Icefjord basin waters of 2011/12

Influence of tides on melting and freezing beneath Filchner-Ronne Ice Shelf, Antarctica

An isopycnic coordinate ocean circulation model is applied to the ocean cavity beneath Filchner-Ronne Ice Shelf, investigating the role of tides on sub-ice shelf circulation and ice shelf basal mass balance. Including tidal forcing causes a significant intensification in the sub-ice shelf circulation, with an increase in melting (3-fold) and refreezing (6-fold); the net melt rate and seawater flux through the cavity approximately doubles. With tidal forcing, the spatial pattern and magnitude of basal melting and freezing generally match observations. The 0.22 m a(-1) net melt rate is close to satellite-derived estimates and at the lower end of oceanographic values. The Ice Shelf Water outflow mixes with shelf waters, forming a cold (<-1.9 degrees C), dense overflow (0.83 Sv) that spills down the continental slope. These results demonstrate that tidal forcing is fundamental to both ice shelf-ocean interactions and deep-water formation in the southern Weddell Sea. Citation: Makinson, K., P. R. Holland, A. Jenkins, K. W. Nicholls, and D. M. Holland (2011), Influence of tides on melting and freezing beneath Filchner-Ronne Ice Shelf, Antarctica, Geophys. Res. Lett., 38, L06601, doi: 10.1029/2010GL046462

Calving localization at Helheim Glacier using multiple local seismic stations

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in The Cryosphere 11 (2017): 609-618, doi:10.5194/tc-11-609-2017.A multiple-station technique for localizing glacier calving events is applied to Helheim Glacier in southeastern Greenland. The difference in seismic-wave arrival times between each pairing of four local seismometers is used to generate a locus of possible event origins in the shape of a hyperbola. The intersection of the hyperbolas provides an estimate of the calving location. This method is used as the P and S waves are not distinguishable due to the proximity of the local seismometers to the event and the emergent nature of calving signals. We find that the seismic waves that arrive at the seismometers are dominated by surface (Rayleigh) waves. The surface-wave velocity for Helheim Glacier is estimated using a grid search with 11 calving events identified at Helheim from August 2014 to August 2015. From this, a catalogue of 11 calving locations is generated, showing that calving preferentially happens at the northern end of Helheim Glacier.The authors acknowledge the support of the Arctic Division of the Office of Polar Programs under grants ARC-0806393 and ARC-1304137

Partitioning uncertainty in projections of Arctic sea ice

Improved knowledge of the contributing sources of uncertainty in projections of Arctic sea ice over the 21st century is essential for evaluating impacts of a changing Arctic environment. Here, we consider the role of internal variability, model structure and emissions scenario in projections of Arctic sea-ice area (SIA) by using six single model initial-condition large ensembles and a suite of models participating in Phase 5 of the Coupled Model Intercomparison Project. For projections of September Arctic SIA change, internal variability accounts for as much as 40%–60% of the total uncertainty in the next decade, while emissions scenario dominates uncertainty toward the end of the century. Model structure accounts for 60%–70% of the total uncertainty by mid-century and declines to 30% at the end of the 21st century in the summer months. For projections of wintertime Arctic SIA change, internal variability contributes as much as 50%–60% of the total uncertainty in the next decade and impacts total uncertainty at longer lead times when compared to the summertime. In winter, there exists a considerable scenario dependence of model uncertainty with relatively larger model uncertainty under strong forcing compared to weak forcing. At regional scales, the contribution of internal variability can vary widely and strongly depends on the calendar month and region. For wintertime SIA change in the Greenland-Iceland-Norwegian and Barents Seas, internal variability contributes 60%–70% to the total uncertainty over the coming decades and remains important much longer than in other regions. We further find that the relative contribution of internal variability to total uncertainty is state-dependent and increases as sea ice volume declines. These results demonstrate that internal variability is a significant source of uncertainty in projections of Arctic sea ice

Partitioning uncertainty in projections of Arctic sea ice

Improved knowledge of the contributing sources of uncertainty in projections of Arctic sea ice over the 21st century is essential for evaluating impacts of a changing Arctic ecosystem. Here, we consider the role of internal variability, model structure and emissions scenario in projections of Arctic sea-ice extent (SIE) by using six single model initial-condition large ensembles and a suite of models participating in Phase 5 of the Coupled Model Intercomparison Project. For projections of September Arctic SIE, internal variability accounts for as much as 60% of the total uncertainty in the next few decades, while emissions scenario dominates uncertainty toward the end of the century. Model structure accounts for approximately 70% of the total uncertainty by mid-century and declines to 20% at the end of the 21st century. For projections of wintertime Arctic SIE, internal variability contributes as much as 60% of the total uncertainty in the first few decades and impacts total uncertainty at longer lead times when compared to summer SIE. Model structure contributes the rest of the uncertainty with emissions scenario contributing little to the total uncertainty. At regional scales, the contribution of internal variability can vary widely and strongly depends on the month and region. For wintertime SIE in the GIN and Barents Seas, internal variability contributes approximately 70% to the total uncertainty over the coming decades and remains important much longer than in other regions. We further find that the relative contribution of internal variability to total uncertainty is state-dependent and increases as sea ice volume declines. These results demonstrate the need to improve the representation of internal variability of Arctic SIE in models, which is a significant source of uncertainty in future projections