| 1. |
- Alam, Assad, et al.
(författare)
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Cooperative driving according to Scoop
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- KTH Royal Institute of Technology and Scania are entering the GCDC 2011 under the name Scoop –Stockholm Cooperative Driving. This paper is an introduction to their team and to the technical approach theyare using in their prototype system for GCDC 2011.
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| 2. |
- Sepp, Hanna, et al.
(författare)
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Children's nutrient intake at preschool and at home
- 2001
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Ingår i: Acta Paediatrica. - : Wiley. - 0803-5253 .- 1651-2227. ; 90:5, s. 483-491
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Tidskriftsartikel (refereegranskat)abstract
- A preschool-based dietary survey, using 7-d records, was carried out in a suburb of Stockholm. The aim was to assess the intake of food and the quality of the diet of preschool children aged 3-5 y at preschool and at home, and to compare the dietary intake with the Swedish dietary recommendations for preschool children. The respective mean intakes of protein, fat, carbohydrates and sucrose, expressed as a percentage of total energy intake were 14, 38, 50 and 9 at preschool, and at home 14, 36, 52 and 12 on weekdays, 14, 34, 55 and 16 on weekend days. The mean intakes of seven vitamins and minerals were low only for selenium as compared with the recommended level. No differences were found in nutrient density between diet at preschool and diet at home, with the exception of dietary fibre (higher at preschool). On weekdays there was a significantly higher nutrient density for calcium, zinc, selenium, vitamin A, riboflavin, vitamin C and dietary fibre compared with weekend days. Conclusion: The average intakes of energy and nutrients per meal at preschool compared with the recommended levels for children aged 4-6 y were low for all meals (breakfast, lunch and afternoon snack). This, however, was compensated for by home meals.
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| 3. |
- Andersson, Tommy, et al.
(författare)
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Women and men sexually violated by closely related perpetrators over a lifespan : Prevalence, revictimization, and association to adverse childhood conditions and experiences
- 2020
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Ingår i: Children and youth services review. - : Elsevier. - 0190-7409 .- 1873-7765. ; 113
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Tidskriftsartikel (refereegranskat)abstract
- Background: Being sexually violated by a perpetrator to whom one has strong emotional and social ties may be exceedingly traumatic as it involves a serious betrayal and violation of basic trust.Objective: To examine the prevalence and revictimization of this type of sexual violence in childhood, adolescence, and adulthood and its covariance with adverse psychosocial conditions and experiences in childhood.Participants and setting: A representative sample of 10,337 Swedish women and men aged 18–74.Method: A combined online and postal survey. Attrition bias was adjusted for by a calibration and weighting procedure based on official register information. Logistic regression was applied to calculate odds ratios (OR) and adjusted odds ratios (AOR).Results: The results showed that 25% of the women and 7% of the men had been sexually violated by closely related perpetrators at some time in their life. Victimization in childhood generated an OR of 4.3 (p < .001) for revictimization in adulthood. Most psychosocial indicators of an adverse childhood situation were significantly linked (OR) to victimization of sexual violence, but insignificant when controlling for the influence of confounders (AOR). The importance of the total burden of psychosocial childhood adversity was illustrated in that 12% of women and 2% of men without indicators of an adverse childhood situation were sexually victimized in adulthood, while the corresponding figures for those reporting at least nine aspects of an adverse childhood situation were 47% and 15%, respectively.Conclusion: The importance of integrating sexual victimization into a holistic psychosocial context in prevention and treatment was emphasized.
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| 4. |
- Braun, Matthias, et al.
(författare)
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Changes of glacial front positions of Vestfonna (Nordaustlandet, Svalbard)
- 2011
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Ingår i: Geografiska Annaler. Series A, Physical Geography. - : Informa UK Limited. - 0435-3676 .- 1468-0459. ; 93:4, s. 301-310
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Tidskriftsartikel (refereegranskat)abstract
- Glaciers in Svalbard have shown considerable mass loss in recent years with a reported acceleration in the western and southern parts of the archipelago. However, for the ice cap Vestfonna, in northeastern Svalbard, climatic mass balance modelling has suggested almost balanced conditions over a period of nine years (2000–2009). A slightly positive geodetic mass balance (1990–2005) has been reported from a comparison of laser altimetry to older DEMs. A heterogeneous situation has been depicted for the various catchments, and hence changes in glacier extent can reveal additional information of glacier status, in particular when dealing with surge-type glaciers. We analysed a 34-year data record of multi-spectral satellite imagery in order to study changes in glacier frontal positions of the ice cap Vestfonna. A consistent pattern of almost steady retreat of the southern and north-eastern outlet glaciers of the ice cap is observed while Franklinbreen, the only major outlet glacier draining towards the north-west shows re-advance. This is consistent with an observed speed up and potential upcoming surge of this outlet. The glacier retreat on the southern coast also agrees with ICESat elevation change measurements. However, due to the glacier response time no direct relations between frontal retreat and surface mass balance can be drawn from the short observation period. The heterogeneous pattern of changes with on-going dynamic adjustments in some areas make the ice cap Vestfonna an ideal test site for future monitoring activities including novel techniques like differential interferometry from bi-static SAR systems.
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| 5. |
- Campbell, Ian, et al.
(författare)
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The evolution of surface flow stripes and stratigraphic folds within Kamb Ice Stream : why don't they match?
- 2008
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Ingår i: Journal of Glaciology. - : International Glaciological Society. - 0022-1430 .- 1727-5652. ; 54:186, s. 421-427
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Tidskriftsartikel (refereegranskat)abstract
- Flow stripes seen in satellite imagery of ice streams and ice shelves are caused by surface undulations with kilometer-scale spacing and meter-scale relief and generally indicate current or recent fast ice flow. On a similar scale, folding of internal ice stratigraphy depicted in cross-flow icepenetrating radar profiles is also a common occurrence in ice streams, suggesting a possible relationship between the two sets of features. We have traced surface flow stripes in RADARSAT and MODIS imagery on Kamb Ice Stream, West Antarctica, from the onset of streaming flow into the near-stagnant trunk. We compare the morphology and evolution of the surface flow stripes to the folds seen in the internal stratigraphy in cross-ice-stream radar profiles. We find essentially no correspondence in the observed locations or spacings between the radar internal layer folds at depths greater than 100 m and the flow stripes on the surface. The gap in the radar data and the surface mappings in the top 100m of firn prevents a precise depiction of how the flow stripes and fold patterns at depth diverge. We explore hypotheses about how flow stripes and internal stratigraphic folds can originate and evolve differently as ice flows downstream. We suggest that flow stripes are subject to surface processes that can modify their morphology independently of the internal stratigraphy, leading to changes in the pattern of flow stripes relative to the internal layers below.
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| 6. |
- Charalampidis, Charalampos, 1983-
(författare)
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Climatology and firn processes in the lower accumulation area of the Greenland ice sheet
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Greenland ice sheet is the largest Northern Hemisphere store of fresh water, and it is responding rapidly to the warming climate. In situ observations document the changing ice sheet properties in the lower accumulation area, Southwest Greenland. Firn densities from 1840 meters above sea level retrieved in May 2012 revealed the existence of a 5.5-meter-thick, near-surface ice layer in response to the recent increased melt and refreezing in firn. As a consequence, vertical meltwater percolation in the extreme summer 2012 was inefficient, resulting in surface runoff. Meltwater percolated and refroze at six meters depth only after the end of the melt season. This prolonged autumn refreezing under the newly accumulated snowpack resulted in unprecedented firn warming with temperature at ten meters depth increased by more than four degrees Celsius. Simulations confirm that meltwater reached nine meters depth at most. The refrozen meltwater was estimated at 0.23 meters water equivalent, amounting to 25 % of the total 2012 ablation.A surface energy balance model was used to evaluate the seasonal and interannual variability of all surface energy fluxes at that elevation in the years 2009 to 2013. Due to the meltwater presence at the surface in 2012, the summer-averaged albedo was significantly reduced (0.71 in 2012; typically 0.78). A sensitivity analysis revealed that 71 % of the subsequent additional solar radiation in 2012 was used for melt, corresponding to 36 % of the total 2012 surface lowering. This interplay between melt and firn properties highlights that the lower accumulation area of the Greenland ice sheet will be responding rapidly in a warming climate.
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| 7. |
- Clemenzi, Ilaria, et al.
(författare)
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Impact of snow distribution modelling for runoff predictions
- 2023
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Ingår i: Nordic Hydrology. - : IWA Publishing. - 0029-1277 .- 1996-9694. ; 54:5, s. 633-647
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Tidskriftsartikel (refereegranskat)abstract
- Snow in the mountains is essential for the water cycle in cold regions. The complexity of the snow processes in such an environment makes it challenging for accurate snow and runoff predictions. Various snow modelling approaches have been developed, especially to improve snow predictions. In this study, we compared the ability to improve runoff predictions in the Överuman Catchment, Northern Sweden, using different parametric representations of snow distribution. They included a temperature-based method, a snowfall distribution (SF) function based on wind characteristics and a snow depletion curve (DC). Moreover, we assessed the benefit of using distributed snow observations in addition to runoff in the hydrological model calibration. We found that models with the SF function based on wind characteristics better predicted the snow water equivalent (SWE) close to the peak of accumulation than models without this function. For runoff predictions, models with the SF function and the DC showed good performances (median Nash–Sutcliffe efficiency equal to 0.71). Despite differences among the calibration criteria for the different snow process representations, snow observations in model calibration added values for SWE and runoff predictions.
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| 8. |
- Dow, Christine F., et al.
(författare)
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Modeling of subglacial hydrological development following rapid supraglacial lake drainage
- 2015
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Ingår i: Journal of Geophysical Research - Earth Surface. - 2169-9003 .- 2169-9011. ; 120:6, s. 1127-1147
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Tidskriftsartikel (refereegranskat)abstract
- The rapid drainage of supraglacial lakes injects substantial volumes of water to the bed of the Greenland ice sheet over short timescales. The effect of these water pulses on the development of basal hydrological systems is largely unknown. To address this, we develop a lake drainage model incorporating both (1) a subglacial radial flux element driven by elastic hydraulic jacking and (2) downstream drainage through a linked channelized and distributed system. Here we present the model and examine whether substantial, efficient subglacial channels can form during or following lake drainage events and their effect on the water pressure in the surrounding distributed system. We force the model with field data from a lake drainage site, 70 km from the terminus of Russell Glacier in West Greenland. The model outputs suggest that efficient subglacial channels do not readily form in the vicinity of the lake during rapid drainage and instead water is evacuated primarily by a transient turbulent sheet and the distributed system. Following lake drainage, channels grow but are not large enough to reduce the water pressure in the surrounding distributed system, unless preexisting channels are present throughout the domain. Our results have implications for the analysis of subglacial hydrological systems in regions where rapid lake drainage provides the primary mechanism for surface-to-bed connections.
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| 9. |
- Doyle, Sam H, et al.
(författare)
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Ice tectonic deformation during the rapid in situ drainage of a supraglacial lake on the Greenland Ice Sheet
- 2013
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Ingår i: The Cryosphere. - : Copernicus GmbH. - 1994-0416 .- 1994-0424. ; 7:1, s. 129-140
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Tidskriftsartikel (refereegranskat)abstract
- We present detailed records of lake discharge, ice motion and passive seismicity capturing the behaviour and processes preceding, during and following the rapid drainage of a 4 km2 supraglacial lake through 1.1-km-thick ice on the western margin of the Greenland Ice Sheet. Peak discharge of 3300 m3 s−1 coincident with maximal rates of vertical uplift indicates that surface water accessed the ice–bed interface causing widespread hydraulic separation and enhanced basal motion. The differential motion of four global positioning system (GPS) receivers located around the lake record the opening and closure of the fractures through which the lake drained. We hypothesise that the majority of discharge occurred through a 3-km-long fracture with a peak width averaged across its wetted length of 0.4 m. We argue that the fracture's kilometre-scale length allowed rapid discharge to be achieved by combining reasonable water velocities with sub-metre fracture widths. These observations add to the currently limited knowledge of in situ supraglacial lake drainage events, which rapidly deliver large volumes of water to the ice–bed interface.
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| 10. |
- Doyle, Samuel H., et al.
(författare)
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Persistent flow acceleration within the interior of the Greenland ice sheet
- 2014
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 41:3, s. 899-905
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Tidskriftsartikel (refereegranskat)abstract
- We present surface velocity measurements from a high-elevation site located 140km from the western margin of the Greenland ice sheet, and similar to 50km into its accumulation area. Annual velocity increased each year from 51.780.01myr(-1) in 2009 to 52.920.01myr(-1) in 2012a net increase of 2.2%. These data also reveal a strong seasonal velocity cycle of up to 8.1% above the winter mean, driven by seasonal melt and supraglacial lake drainage. Sole et al. (2013) recently argued that ice motion in the ablation area is mediated by reduced winter flow following the development of efficient subglacial drainage during warmer, faster, summers. Our data extend this analysis and reveal a year-on-year increase in annual velocity above the equilibrium line altitude, where despite surface melt increasing, it is still sufficiently low to hinder the development of efficient drainage under thick ice. Key Points Ice flow in the accumulation area accelerated year-on-year between 2009 and 2012 The acceleration correlates with the inland expansion of supraglacial lakes This dynamic response contrasts with observations from the ablation zone
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