| 1. |
- Kennicutt, M. C., et al.
(författare)
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Delivering 21st century Antarctic and Southern Ocean science
- 2016
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Ingår i: Antarctic Science. - 0954-1020 .- 1365-2079. ; 28, s. 407-423
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Tidskriftsartikel (refereegranskat)abstract
- © Antarctic Science Ltd 2016.The Antarctic Roadmap Challenges (ARC) project identified critical requirements to deliver high priority Antarctic research in the 21st century. The ARC project addressed the challenges of enabling technologies, facilitating access, providing logistics and infrastructure, and capitalizing on international co-operation. Technological requirements include: i) innovative automated in situ observing systems, sensors and interoperable platforms (including power demands), ii) realistic and holistic numerical models, iii) enhanced remote sensing and sensors, iv) expanded sample collection and retrieval technologies, and v) greater cyber-infrastructure to process 'big data' collection, transmission and analyses while promoting data accessibility. These technologies must be widely available, performance and reliability must be improved and technologies used elsewhere must be applied to the Antarctic. Considerable Antarctic research is field-based, making access to vital geographical targets essential. Future research will require continent- and ocean-wide environmentally responsible access to coastal and interior Antarctica and the Southern Ocean. Year-round access is indispensable. The cost of future Antarctic science is great but there are opportunities for all to participate commensurate with national resources, expertise and interests. The scope of future Antarctic research will necessitate enhanced and inventive interdisciplinary and international collaborations. The full promise of Antarctic science will only be realized if nations act together.
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| 2. |
- Dotto, T. S., et al.
(författare)
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Ocean variability beneath Thwaites Eastern Ice Shelf driven by the Pine Island Bay Gyre strength
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- West Antarctic ice-shelf thinning is primarily caused by ocean-driven basal melting. Here we assess ocean variability below Thwaites Eastern Ice Shelf (TEIS) and reveal the importance of local ocean circulation and sea-ice. Measurements obtained from two sub-ice-shelf moorings, spanning January 2020 to March 2021, show warming of the ice-shelf cavity and an increase in meltwater fraction of the upper sub-ice layer. Combined with ocean modelling results, our observations suggest that meltwater from Pine Island Ice Shelf feeds into the TEIS cavity, adding to horizontal heat transport there. We propose that a weakening of the Pine Island Bay gyre caused by prolonged sea-ice cover from April 2020 to March 2021 allowed meltwater-enriched waters to enter the TEIS cavity, which increased the temperature of the upper layer. Our study highlights the sensitivity of ocean circulation beneath ice shelves to local atmosphere-sea-ice-ocean forcing in neighbouring open oceans.
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| 3. |
- Hogan, K. A., et al.
(författare)
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Revealing the former bed of Thwaites Glacier using sea-floor bathymetry: implications for warm-water routing and bed controls on ice flow and buttressing
- 2020
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Ingår i: Cryosphere. - : Copernicus GmbH. - 1994-0416. ; 14:9, s. 2883-2908
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Tidskriftsartikel (refereegranskat)abstract
- The geometry of the sea floor immediately beyond Antarctica's marine-terminating glaciers is a fundamental control on warm-water routing, but it also describes former topographic pinning points that have been important for ice-shelf buttressing. Unfortunately, this information is often lacking due to the inaccessibility of these areas for survey, leading to modelled or interpolated bathymetries being used as boundary conditions in numerical modelling simulations. At Thwaites Glacier (TG) this critical data gap was addressed in 2019 during the first cruise of the International Thwaites Glacier Collaboration (ITGC) project. We present more than 2000 km(2) of new multibeam echo-sounder (MBES) data acquired in exceptional sea-ice conditions immediately offshore TG, and we update existing bathymetric compilations. The cross-sectional areas of sea-floor troughs are under-predicted by up to 40% or are not resolved at all where MBES data are missing, suggesting that calculations of trough capacity, and thus oceanic heat flux, may be significantly underestimated. Spatial variations in the morphology of topographic highs, known to be former pinning points for the floating ice shelf of TG, indicate differences in bed composition that are supported by landform evidence. We discuss links to ice dynamics for an overriding ice mass including a potential positive feedback mechanism where erosion of soft erodible highs may lead to ice-shelf ungrounding even with little or no ice thinning. Analyses of bed roughnesses and basal drag contributions show that the sea-floor bathymetry in front of TG is an analogue for extant bed areas. Ice flow over the sea-floor troughs and ridges would have been affected by similarly high basal drag to that acting at the grounding zone today. We conclude that more can certainly be gleaned from these 3D bathymetric datasets regarding the likely spatial variability of bed roughness and bed composition types underneath TG. This work also addresses the requirements of recent numerical ice-sheet and ocean modelling studies that have recognised the need for accurate and high-resolution bathymetry to determine warm-water routing to the grounding zone and, ultimately, for predicting glacier retreat behaviour.
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| 4. |
- Allentoft, Morten E., et al.
(författare)
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Population genomics of post-glacial western Eurasia
- 2024
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 625:7994, s. 301-311
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Tidskriftsartikel (refereegranskat)abstract
- Western Eurasia witnessed several large-scale human migrations during the Holocene1–5. Here, to investigate the cross-continental effects of these migrations, we shotgun-sequenced 317 genomes—mainly from the Mesolithic and Neolithic periods—from across northern and western Eurasia. These were imputed alongside published data to obtain diploid genotypes from more than 1,600 ancient humans. Our analyses revealed a ‘great divide’ genomic boundary extending from the Black Sea to the Baltic. Mesolithic hunter-gatherers were highly genetically differentiated east and west of this zone, and the effect of the neolithization was equally disparate. Large-scale ancestry shifts occurred in the west as farming was introduced, including near-total replacement of hunter-gatherers in many areas, whereas no substantial ancestry shifts happened east of the zone during the same period. Similarly, relatedness decreased in the west from the Neolithic transition onwards, whereas, east of the Urals, relatedness remained high until around 4,000 bp, consistent with the persistence of localized groups of hunter-gatherers. The boundary dissolved when Yamnaya-related ancestry spread across western Eurasia around 5,000 bp, resulting in a second major turnover that reached most parts of Europe within a 1,000-year span. The genetic origin and fate of the Yamnaya have remained elusive, but we show that hunter-gatherers from the Middle Don region contributed ancestry to them. Yamnaya groups later admixed with individuals associated with the Globular Amphora culture before expanding into Europe. Similar turnovers occurred in western Siberia, where we report new genomic data from a ‘Neolithic steppe’ cline spanning the Siberian forest steppe to Lake Baikal. These prehistoric migrations had profound and lasting effects on the genetic diversity of Eurasian populations.
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| 5. |
- Bensi, M., et al.
(författare)
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Deep flow variability offshore south-west Svalbard (fram strait)
- 2019
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Ingår i: Water. - : MDPI AG. - 2073-4441. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- - Water mass generation and mixing in the eastern Fram Strait are strongly influenced by the interaction between Atlantic and Arctic waters and by the local atmospheric forcing, which produce dense water that substantially contributes to maintaining the global thermohaline circulation. The West Spitsbergen margin is an ideal area to study such processes. Hence, in order to investigate the deep flow variability on short-term, seasonal, and multiannual timescales, two moorings were deployed at ~1040 m depth on the southwest Spitsbergen continental slope. We present and discuss time series data collected between June 2014 and June 2016. They reveal thermohaline and current fluctuations that were largest from October to April, when the deep layer, typically occupied by Norwegian Sea Deep Water, was perturbed by sporadic intrusions of warmer, saltier, and less dense water. Surprisingly, the observed anomalies occurred quasi-simultaneously at both sites, despite their distance (~170 km). We argue that these anomalies may arise mainly by the effect of topographically trapped waves excited and modulated by atmospheric forcing. Propagation of internal waves causes a change in the vertical distribution of the Atlantic water, which can reach deep layers. During such events, strong currents typically precede thermohaline variations without significant changes in turbidity. However, turbidity increases during April-June in concomitance with enhanced downslope currents. Since prolonged injections of warm water within the deep layer could lead to a progressive reduction of the density of the abyssal water moving toward the Arctic Ocean, understanding the interplay between shelf, slope, and deep waters along the west Spitsbergen margin could be crucial for making projections on future changes in the global thermohaline circulation. © 2019 by the authors.
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| 6. |
- Dotto, T. S., et al.
(författare)
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Wind-Driven Processes Controlling Oceanic Heat Delivery to the Amundsen Sea, Antarctica
- 2019
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Ingår i: Journal of Physical Oceanography. - : American Meteorological Society. - 0022-3670 .- 1520-0485. ; 49:11, s. 2829-2849
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Tidskriftsartikel (refereegranskat)abstract
- Variability in the heat delivery by Circumpolar Deep Water (CDW) is responsible for modulating the basal melting of the Amundsen Sea ice shelves. However, the mechanisms controlling the CDW inflow to the region's continental shelf remain little understood. Here, a high-resolution regional model is used to assess the processes governing heat delivery to the Amundsen Sea. The key mechanisms are identified by decomposing CDW temperature variability into two components associated with 1) changes in the depth of isopycnals [heave (HVE)], and 2) changes in the temperature of isopycnals [water mass property changes (WMP)]. In the Dotson-Getz trough, CDW temperature variability is primarily associated with WMP. The deeper thermocline and shallower shelf break hinder CDW access to that trough, and CDW inflow is regulated by the uplift of isopycnals at the shelf break-which is itself controlled by wind-driven variations in the speed of an undercurrent flowing eastward along the continental slope. In contrast, CDW temperature variability in the Pine Island-Thwaites trough is mainly linked to HVE. The shallower thermocline and deeper shelf break there permit CDW to persistently access the continental shelf. CDW temperature in the area responds to wind-driven modulation of the water mass on-shelf volume by changes in the rate of inflow across the shelf break and in Ekman pumping-induced vertical displacement of isopycnals within the shelf. The western and eastern Amundsen Sea thus represent distinct regimes, in which wind forcing governs CDW-mediated heat delivery via different dynamics.
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| 7. |
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| 8. |
- Graham, Alastair G.C., et al.
(författare)
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Rapid retreat of Thwaites Glacier in the pre-satellite era
- 2022
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Ingår i: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 15, s. 706-713
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the recent history of Thwaites Glacier, and the processes controlling its ongoing retreat, is key to projecting Antarctic contributions to future sea-level rise. Of particular concern is how the glacier grounding zone might evolve over coming decades where it is stabilized by sea-floor bathymetric highs. Here we use geophysical data from an autonomous underwater vehicle deployed at the Thwaites Glacier ice front, to document the ocean-floor imprint of past retreat from a sea-bed promontory. We show patterns of back-stepping sedimentary ridges formed daily by a mechanism of tidal lifting and settling at the grounding line at a time when Thwaites Glacier was more advanced than it is today. Over a duration of 5.5 months, Thwaites grounding zone retreated at a rate of >2.1 km per year—twice the rate observed by satellite at the fastest retreating part of the grounding zone between 2011 and 2019. Our results suggest that sustained pulses of rapid retreat have occurred at Thwaites Glacier in the past two centuries. Similar rapid retreat pulses are likely to occur in the near future when the grounding zone migrates back off stabilizing high points on the sea floor.
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| 9. |
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| 10. |
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| 11. |
- Wåhlin, Anna, 1970, et al.
(författare)
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Pathways and modification of warm water flowing beneath Thwaites Ice Shelf, West Antarctica
- 2021
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:15
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Tidskriftsartikel (refereegranskat)abstract
- Thwaites Glacier is the most rapidly changing outlet of the West Antarctic Ice Sheet and adds large uncertainty to 21st century sea-level rise predictions. Here, we present the first direct observations of ocean temperature, salinity, and oxygen beneath Thwaites Ice Shelf front, collected by an autonomous underwater vehicle. On the basis of these data, pathways and modification of water flowing into the cavity are identified. Deep water underneath the central ice shelf derives from a previously underestimated eastern branch of warm water entering the cavity from Pine Island Bay. Inflow of warm and outflow of melt-enriched waters are identified in two seafloor troughs to the north. Spatial property gradients highlight a previously unknown convergence zone in one trough, where different water masses meet and mix. Our observations show warm water impinging from all sides on pinning points critical to ice-shelf stability, a scenario that may lead to unpinning and retreat.
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| 12. |
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| 13. |
- Al-Mashhadi, Ammar Nadhom Farman, et al.
(författare)
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Changes in arterial pressure and markers of nitric oxide homeostasis and oxidative stress following surgical correction of hydronephrosis in children
- 2018
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Ingår i: Pediatric nephrology (Berlin, West). - : Springer. - 0931-041X .- 1432-198X. ; 33:4, s. 639-649
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Tidskriftsartikel (refereegranskat)abstract
- Objective Recent clinical studies have suggested an increased risk of elevated arterial pressure in patients with hydronephrosis. Animals with experimentally induced hydronephrosis develop hypertension, which is correlated to the degree of obstruction and increased oxidative stress. In this prospective study we investigated changes in arterial pressure, oxidative stress, and nitric oxide (NO) homeostasis following correction of hydronephrosis.Methods Ambulatory arterial pressure (24 h) was monitored in pediatric patients with hydronephrosis (n = 15) before and after surgical correction, and the measurements were compared with arterial pressure measurements in two control groups, i.e. healthy controls (n = 8) and operated controls (n = 8). Markers of oxidative stress and NO homeostasis were analyzed in matched urine and plasma samples.Results The preoperative mean arterial pressure was significantly higher in hydronephrotic patients [83 mmHg; 95% confidence interval (CI) 80–88 mmHg] than in healthy controls (74 mmHg; 95% CI 68–80 mmHg; p < 0.05), and surgical correction of ureteral obstruction reduced arterial pressure (76 mmHg; 95% CI 74–79 mmHg; p < 0.05). Markers of oxidative stress (i.e., 11- dehydroTXB2, PGF2α, 8-iso-PGF2α, 8,12-iso-iPF2α-VI) were significantly increased (p < 0.05) in patients with hydronephrosis compared with both control groups, and these were reduced following surgery (p < 0.05). Interestingly, there was a trend for increased NO synthase activity and signaling in hydronephrosis, which may indicate compensatory mechanism(s).Conclusion This study demonstrates increased arterial pressure and oxidative stress in children with hydronephrosis compared with healthy controls, which can be restored to normal levels by surgical correction of the obstruction. Once reference data on ambulatory blood pressure in this young age group become available, we hope cut-off values can be defined for deciding whether or not to correct hydronephrosis surgically.Keywords Blood pressure . Hydronephrosis . Hypertension . Nitric oxide . Oxidative stress . Ureteral obstruction
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| 14. |
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| 15. |
- Allentoft, Morten E., et al.
(författare)
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100 ancient genomes show repeated population turnovers in Neolithic Denmark
- 2024
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 625, s. 329-337
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Tidskriftsartikel (refereegranskat)abstract
- Major migration events in Holocene Eurasia have been characterized genetically at broad regional scales1–4. However, insights into the population dynamics in the contact zones are hampered by a lack of ancient genomic data sampled at high spatiotemporal resolution5–7. Here, to address this, we analysed shotgun-sequenced genomes from 100 skeletons spanning 7,300 years of the Mesolithic period, Neolithic period and Early Bronze Age in Denmark and integrated these with proxies for diet (13C and 15N content), mobility (87Sr/86Sr ratio) and vegetation cover (pollen). We observe that Danish Mesolithic individuals of the Maglemose, Kongemose and Ertebølle cultures form a distinct genetic cluster related to other Western European hunter-gatherers. Despite shifts in material culture they displayed genetic homogeneity from around 10,500 to 5,900 calibrated years before present, when Neolithic farmers with Anatolian-derived ancestry arrived. Although the Neolithic transition was delayed by more than a millennium relative to Central Europe, it was very abrupt and resulted in a population turnover with limited genetic contribution from local hunter-gatherers. The succeeding Neolithic population, associated with the Funnel Beaker culture, persisted for only about 1,000 years before immigrants with eastern Steppe-derived ancestry arrived. This second and equally rapid population replacement gave rise to the Single Grave culture with an ancestry profile more similar to present-day Danes. In our multiproxy dataset, these major demographic events are manifested as parallel shifts in genotype, phenotype, diet and land use.
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| 16. |
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| 17. |
- Andersson, B, et al.
(författare)
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Ökad fysisk aktivitet viktigt för att bromsa sjukfrånvaron
- 2015
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Ingår i: Dagens nyheter, DN.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Försäkringskassans rapport (DN Debatt 27/11 2015) visar att sjukfrånvaron fortsätter att öka och lovar att kraftsamla i sjukförsäkringshandläggningen. Men, precis som Försäkringskassan skriver, kommer det inte att räcka för att nå regeringens mål. Regeringens åtgärdsprograms program i sju punkter för att minska sjukfrånvaron saknar en viktig komponent. Det måste kompletteras med fysisk aktivitet som ett åttonde område för att trenden ska kunna brytas, skriver 13 debattörer.
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| 18. |
- Arcalis-planas, A., et al.
(författare)
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Limited use of sea ice by the Ross seal (Ommatophoca rossii), in Amundsen Sea, Antarctica, using telemetry and remote sensing data
- 2015
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Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 38:4, s. 445-461
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Tidskriftsartikel (refereegranskat)abstract
- To understand the use and importance of the Antarctic sea ice to the Ross seal (Ommatophoca rossii), four adult females were tagged with Argos satellite transmitters in the Amundsen Sea, Antarctica. The Ross seal is the least studied of the Antarctic seal species and nothing was previously known about their behaviour in the Amundsen Sea. During almost 1 year, their movements, haul out behaviour and time spent at different temperatures were logged. By comparing their movements with daily ice maps, distances to the ice edge were calculated, and seals dependence on sea ice for resting, breeding and moulting was analysed. The tagged seals spent on average 70.8 % (range 66.8–77.8 %) of their time in the water and hauled out mainly during the moult in December–January, and in late October–mid-November during breeding. During the pelagic period, they were on average 837.5 km (range 587–1,282 km) from the ice edge indicating a fully pelagic life during several months. Their pelagic behaviour suggests that Ross seals, although being an ice obligate species, may adapt comparatively easy to climate change involving ice melting and recession and thereby potentially being less sensitive to the reduction of sea ice than other Antarctic seal species. Although nothing is known about their mating behaviour, they appear to be relatively stationary during moulting and breeding, hence requiring a small ice surface. Although previous studies in other parts of Antarctica have found similar results, still many questions remain about this peculiar species.
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| 19. |
- Becker, Jeroen H, et al.
(författare)
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ST Analysis of the Fetal Electrocardiogram in Intrapartum Fetal Monitoring: A Meta-Analysis.
- 2012
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Ingår i: Obstetrics and Gynecology. - 1873-233X. ; 119:1, s. 145-154
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Forskningsöversikt (refereegranskat)abstract
- OBJECTIVE:: To compare the effects of ST-waveform analysis in combination with cardiotocography with conventional cardiotocography for intrapartum fetal monitoring. DATA SOURCES:: We searched MEDLINE, Embase, and PubMed for randomized controlled trials (RCTs) evaluating ST-waveform analysis for intrapartum fetal monitoring. METHODS OF STUDY SELECTION:: We identified RCTs that compared ST-waveform analysis and conventional cardiotocography for intrapartum fetal monitoring of singleton pregnancies in cephalic presentation beyond 34 weeks of gestation and evaluating at least one of the following: metabolic acidosis, umbilical cord pH less than 7.15, umbilical cord pH less than 7.10, umbilical cord pH less than 7.05, umbilical cord pH less than 7.00, Apgar scores less than 7 at 5 minutes, admittance to the neonatal intensive care unit, need for intubation, presence of hypoxic ischemic encephalopathy, perinatal death, operative delivery, and number of fetal blood samplings. TABULATION, INTEGRATION, AND RESULTS:: Five RCTs, which included 15,352 patients, met the selection criteria. Random-effects models were used to estimate the combined relative risks (RRs) of ST analysis compared with conventional cardiotocography. Compared with conventional cardiotocography, ST analysis showed a nonsignificant reduction in metabolic acidosis (RR 0.72, 95% confidence interval 0.43-1.19, number needed to treat [NNT] 357). ST analysis significantly reduced the incidence of additional fetal blood sampling (RR 0.59, 95% confidence interval 0.44-0.79, NNT 11), operative vaginal deliveries (RR 0.88, 95% confidence interval 0.80-0.97, NNT 64), and total operative deliveries (RR 0.94, 95% confidence interval 0.89-0.99, NNT 64). For other outcomes, no differences in effect were seen between ST analysis and conventional cardiotocography, or data were not suitable for meta-analysis. CONCLUSION:: The additional use of ST analysis for intrapartum monitoring reduced the incidence of operative vaginal deliveries and the need for fetal blood sampling but did not reduce the incidence of metabolic acidosis at birth.
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| 20. |
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| 21. |
- Carlström, Mattias, et al.
(författare)
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Hydronephrosis causes salt-sensitive hypertension and impaired renal concentrating ability in mice
- 2007
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Ingår i: Acta Physiologica. - : Wiley. - 1748-1708 .- 1748-1716. ; 189:3, s. 293-301
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Hypertension is a common disease in the industrialized world and approximately 5% of all cases are secondary to kidney malfunction. We have recently shown that hydronephrosis due to partial unilateral ureteral obstruction (PUUO) causes salt-sensitive hypertension in rats. The mechanisms are still unclear, but appear to be intrarenal and primarily located to the diseased kidney. In the present study, we have developed a model for PUUO to study if hydronephrotic mice develop salt-sensitive hypertension. Methods: PUUO was created in 3-week-old mice (C57bl/6J). Blood pressure and heart rate were measured telemetrically in adult animals on normal and high salt diets. Metabolism cages were used to study the renal excretion of electrolytes and water. Plasma samples for renin analysis were collected and renal histological changes were evaluated. Results: All hydronephrotic animals developed salt-sensitive hypertension that correlated to the degree of hydronephrosis. In hydronephrotic animals, blood pressure increased from 114 ± 1 mmHg on normal salt diet to 120 ± 2 mmHg on high salt diet, compared with 103 ± 1 to 104 ± 1 in controls. Hydronephrotic animals showed increased diuresis and reduced ability to regulate electrolyte concentration. No differences in plasma renin concentration were found between the groups. The parenchymal weight and glomerular area of contralateral kidneys were significantly increased in the hydronephrotic animals. Histopathology of the hydronephrotic kidneys displayed areas with fibrosis, inflammation and glomerular changes. Conclusion: This study provides a model for PUUO in mice and demonstrates the presence of salt-sensitive hypertension and an impaired renal concentrating ability in mice which has not been described before.
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| 22. |
- Carlström, Mattias, et al.
(författare)
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Hydronephrosis causes salt-sensitive hypertension in rats
- 2006
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Ingår i: Journal of Hypertension. - : Ovid Technologies (Wolters Kluwer Health). - 0263-6352 .- 1473-5598. ; 24:7, s. 1437-1443
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Hypertension is a common disease in the Western world and approximately 5% of all cases are secondary to kidney malfunction. It is not clear whether unilateral hydronephrosis due to partial obstruction affects blood pressure. AIM: The aim of this study was to determine whether hypertension develops and to investigate the effects of different salt diets on the blood pressure in hydronephrotic animals. METHODS: Unilateral partial ureteral obstruction was created in 3-week-old Sprague-Dawley rats. A telemetric device was implanted 4-6 weeks later and blood pressure was measured on normal, low- and high-salt diets. Plasma samples were collected on all diets for renin analysis. RESULTS: All hydronephrotic animals developed hypertension that correlated to the degree of hydronephrosis. The blood pressure increased slowly with time and was salt sensitive. In severe hydronephrosis, blood pressure increased from 118 ± 5 mmHg on low salt to 140 ± 6 mmHg on high salt intake, compared to control levels of 82 ± 2 and 84 ± 2 mmHg, respectively. Plasma renin concentration was increased in the hydronephrotic group of animals compared to controls on all diets, but the difference was only significant on a normal salt diet, 165 ± 15 versus 86 ± 12 μGU/ml respectively. In animals with severe hydronephrosis the plasma renin levels were lower, and the changes less, than in those with mild and moderate hydronephrosis. CONCLUSION: This study demonstrates the presence of a salt-sensitive hypertension in hydronephrosis. A systemic effect of the renin-angiotensin system alone cannot be responsible for the hypertension.
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| 23. |
- Carlström, Mattias, et al.
(författare)
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Relief of chronic partial ureteral obstruction attenuates salt-sensitive hypertension in rats
- 2007
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Ingår i: Acta Physiologica. - : Wiley. - 1748-1708 .- 1748-1716. ; 189:1, s. 67-75
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The incidence of hydronephrosis due to ureteropelvic junction obstruction is approx. 0.5%. During the last decade, the management of non-symptomatic hydronephrosis has become much more conservative, but the long-term physiological consequences of this policy are not clear. Previously, we have shown that animals with chronic partial unilateral ureteral obstruction develop salt-sensitive hypertension. In this study, the effects of ipsilateral and contralateral nephrectomy and ureterovesicostomy on blood pressure were studied in hydronephrotic animals. Methods: Partial unilateral ureteral obstruction was created in 3-week-old male Sprague–Dawley rats and blood pressure was measured telemetrically 4–6 weeks later during a normal and high salt diet before and after uninephrectomy or ureterovesicostomy. Plasma samples for renin assay were collected during both diets before and after ipsilateral nephrectomy. Results: All hydronephrotic animals developed salt-sensitive hypertension, of different degrees. Before nephrectomy the plasma renin concentration was significantly higher in the hydronephrotic animals than in controls (160 ± 15 μGU mL−1 vs. 96 ± 12 μGU mL−1, respectively), but after the ipsilateral nephrectomy no differences were found between the groups. In the hydronephrotic animals both ipsilateral nephrectomy and ureterovesicostomy reduced the blood pressure and salt-sensitivity but the former still differed significantly from the controls. In contralaterally, nephrectomized hydronephrotic animals the salt-sensitive hypertension became more pronounced. Conclusion: Hydronephrosis in rats causes salt-sensitive hypertension that can be markedly reduced by removing the hydronephrotic kidney or relieving the obstruction by ureterovesicostomy. The mechanisms appear to be intrarenal and primarily located in the diseased kidney, but a secondary mechanism is also present.
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| 24. |
- Carlström, Mattias, et al.
(författare)
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Role of nitric oxide deficiency in the development of hypertension in hydronephrotic animals
- 2008
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Ingår i: American Journal of Physiology - Renal Physiology. - : American Physiological Society. - 0363-6127 .- 1522-1466 .- 1931-857X. ; 294:2, s. 362-370
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Tidskriftsartikel (refereegranskat)abstract
- Hydronephrotic animals develop renal injury and hypertension, which is associated with an abnormal tubuloglomerular feedback (TGF). The TGF sensitivity is coupled to nitric oxide (NO) in the macula densa. The involvement of reduced NO availability in the development of hypertension in hydronephrosis was investigated. Hydronephrosis was induced by ureteral obstruction in young rats. Blood pressure and renal excretion were measured in adulthood, under different sodium conditions, and before and after chronic administration of either N-G- nitro-L-arginine methyl ester (L-NAME) or L-arginine. Blood samples for ADMA, SDMA, and L-arginine analysis were taken and the renal tissue was used for histology and determination of NO synthase (NOS) proteins. TGF characteristics were determined by stop-flow pressure technique before and after administration of 7-nitroindazole (7-NI) or L-arginine. Hydronephrotic animals developed salt-sensitive hypertension, which was associated with pressure natriuresis and diuresis. The blood pressure response to L-NAME was attenuated and L-arginine supplementation decreased blood pressure in hydronephrotic animals, but not in the controls. Under control conditions, reactivity and sensitivity of the TGF response were greater in the hydronephrotic group. 7-NI administration increased TGF reactivity and sensitivity in control animals, whereas, in hydronephrotic animals, neuronal NOS (nNOS) inhibition had no effect. L-Arginine attenuated TGF response more in hydronephrotic kidneys than in controls. The hydronephrotic animals displayed various degrees of histopathological changes. ADMA and SDMA levels were higher and the renal expressions of nNOS and endothelial NOS proteins were lower in animals with hydronephrosis. Reduced NO availability in the diseased kidney in hydronephrosis, and subsequent resetting of the TGF mechanism, plays an important role in the development of hypertension.
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| 25. |
- Fällström, Karl-Evert, et al.
(författare)
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Transient bending waves in anisotropic plates studied by hologram interferometry
- 1989
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Ingår i: Experimental mechanics. - 0014-4851 .- 1741-2765. ; 29:4, s. 409-413
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Tidskriftsartikel (refereegranskat)abstract
- Propagating bending waves are studied in plates made of glass-fiber reinforced polyester. The waves are generated by the impact of a ballistic pendulum. Hologram interferometry, with a double pulsed ruby laser as light source, is used to record the out of plane motion of the waves. The interferograms have an elliptic-like symmetry for an orthotropic plate, while the wave pattern for a symmetric angle-ply reinforced plate has a symmetry about the axes of reinforcements. Experimental data are compared on one hand to analytical results obtained by assuming that the orthotropic plate can be described as if isotropic along the main axes, and on the other hand to numerical results from calculations using the finite-element method. The effective Young's modulus raised to power 1/4 is shown to be an important parameter for the description of the dispersive wave pattern. A defect in the plate alters the wave pattern in the interferograms significantly. This may have technical use.
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| 26. |
- Hernandez-Molina, F. J., et al.
(författare)
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Oceanographic processes and morphosedimentary products along the Iberian margins: A new multidisciplinary approach
- 2016
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Ingår i: Marine Geology. - : Elsevier BV. - 0025-3227. ; 378, s. 127-156
-
Tidskriftsartikel (refereegranskat)abstract
- Our understanding of bottom-currents and associated oceanographic processes (e.g., overflows, barotropic tidal currents) including intermittent processes (e.g., vertical eddies, deep sea storms, horizontal vortices, internal waves and tsunamis) is rapidly evolving. Many deep-water processes remain poorly understood due to limited direct observations, but can generate significant depositional and erosional features on both short and long term time scales. This paper represents a review work, which describes for the first time these oceanographic processes and examines their potential role in the sedimentary features along the Iberian continental margins. This review explores the implications of the studied processes, given their secondary role relative to other factors such as mass-transport and turbiditic processes, and highlights three major results: a) contourite depositional and erosional features are ubiquitous along the margins, indicating that bottom currents and associated oceanographic processes control the physiography and sedimentation; b) the position of interfaces between major water masses and their vertical and spatial variation in time specifically appears to exert primary control in determining major morphologic changes along the slope gradient, including the contourite terraces development; and c) contourites deposits exhibit greater variation than the established fades model suggests. Therefore, a consistent facies model however faces substantial challenges in terms of the wide range of oceanographic processes that can influence in their development. An integrated interpretation of these oceanographic processes requires an understanding of contourites, seafloor features, their spatial and temporal evolution, and the near-bottom flows that form them. This approach will synthesize oceanographic data, seafloor morphology, sediments and seismic images to improve our knowledge of permanent and intermittent processes around Iberia, and evaluate their conceptual and regional role in the margin's sedimentary evolution. Given their complexes, three-dimensional and temporally-variable nature, integration of these processes into sedimentary, oceanographic and climatological frameworks will require a multidisciplinary approach that includes Geology, Physical oceanography, Paleoceanography and Benthic Biology.
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| 27. |
- Hernandez Molina, Javier, et al.
(författare)
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Oceanographic processes and products around the Iberian margin: a new multidisciplinary approach : Procesos oceanográficos y sus productos alrededor del margen de Iberia: una nueva aproximación multidisciplinar
- 2015
-
Ingår i: Boletín Geológico y Minero. - 0366-0176 .- 0366-0176. ; 126:2-3, s. 279-326
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Tidskriftsartikel (refereegranskat)abstract
- Our understanding of the role of bottom-current and associated oceanographic processes (as overflows, barotropic currents, tides or intermittent processes like giant vertical eddies, deep sea storms, horizontal vortices, internal waves and tsunamis) is rapidly improving. But, most of these oceanographic deep-water processes remains poorly understood and have been rarely observed but believed to be capable of generating depositional and erosional features in many contexts at both short and long term. In present compilation we described these oceanographic processes including examples or their potential role in the sedimentation processes around the Iberia margin. Importance of these processes is highlighted and its implication discussed to demonstrate that these oceanographic processes are very important is affecting the shape and evolution of the Iberian continental margin and adjacent oceanic basins although is not still considered as important as other factors as mass-transport deposits and turbiditic processes. To have a better understanding on the implication of all these oceanographic processes connections have to be made between (contourite) sea-floor features, their spatial and temporal evolution, and the near-bottom flows that form them. The only way to achieve that in next decades is by a more intensive collaboration between specialist from Geology, Oceanography and Benthic Biology in new multi-disciplinary studies. Consequently, further multi-disciplinary approach uses oceanographic data, sea-floor morphology, sediments and seismic characterization will be essential for improve our knowledge of these permanent and intermittent processes around Iberia and evaluate their conceptual and regional role in the margins evolution over time and space.
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| 28. |
- Ketzel, M., et al.
(författare)
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Estimation and validation of PM2.5/PM10 exhaust and non-exhaust emission factors for practical street pollution modelling
- 2007
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Ingår i: Atmos. Environ.. - : Elsevier BV. ; 41, s. 9370-9385
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Tidskriftsartikel (refereegranskat)abstract
- In order to carry out efficient traffic and air quality management, validated models and PM emission estimates are needed. This paper compares current available emission factor estimates for PM10 and PM2.5 from emission databases and different emission models, and validates these against eight high quality street pollution measurements in Denmark, Sweden, Germany, Finland and Austria.The data sets show large variation of the PM concentration and emission factors with season and with location. Consistently at all roads the PM10 and PM2.5 emission factors are lower in the summer month than the rest of the year. For example, PM10 emission factors are in average 5–45% lower during the month 6–10 compared to the annual average.The range of observed total emission factors (including non-exhaust emissions) for the different sites during summer conditions are 80–130 mg km−1 for PM10, 30–60 mg km−1 for PM2.5 and 20–50 mg km−1 for the exhaust emissions.We present two different strategies regarding modelling of PM emissions: (1) For Nordic conditions with strong seasonal variations due to studded tyres and the use of sand/salt as anti-skid treatment a time varying emission model is needed. An empirical model accounting for these Nordic conditions was previously developed in Sweden. (2) For other roads with a less pronounced seasonal variation (e.g. in Denmark, Germany, Austria) methods using a constant emission factor maybe appropriate. Two models are presented here.Further, we apply the different emission models to data sets outside the original countries. For example, we apply the “Swedish” model for two streets without studded tyre usage and the “German” model for Nordic data sets. The “Swedish” empirical model performs best for streets with studded tyre use, but was not able to improve the correlation versus measurements in comparison to using constant emission factors for the Danish side. The “German” method performed well for the streets without clear seasonal variation and reproduces the summer conditions for streets with pronounced seasonal variation. However, the seasonal variation of PM emission factors can be important even for countries not using studded tyres, e.g. in areas with cold weather and snow events using sand and de-icing materials. Here a constant emission factor probably will under-estimate the 90-percentiles and therefore a time varying emission model need to be used or developed for such areas.All emission factor models consistently indicate that a large part (about 50–85% depending on the location) of the total PM10 emissions originates from non-exhaust emissions. This implies that reduction measures for the exhaust part of the vehicle emissions will only have a limited effect on ambient PM10 levels.
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| 29. |
- Kim, T. W., et al.
(författare)
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Interannual Variation of Modified Circumpolar Deep Water in the Dotson-Getz Trough, West Antarctica
- 2021
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Ingår i: Journal of Geophysical Research: Oceans. - 2169-9275. ; 126:12
-
Tidskriftsartikel (refereegranskat)abstract
- Widespread ice shelf thinning has been recorded in the Amundsen Sea in recent decades, driven by basal melting and intrusions of relatively warm Circumpolar Deep Water (CDW) onto the continental shelf. The Dotson Ice Shelf (DIS) is located to the south of the Amundsen Sea polynya, and has a high basal melting rate because modified CDW (mCDW) fills the Dotson-Getz Trough (DGT) and reaches the base of the ice shelf. Here, hydrographic data in the DGT obtained during seven oceanographic surveys from 2007 to 2018 were used to study the interannual variation in mCDW volume and properties and their causes. Although mCDW volume showed relatively weak interannual variations at the continental shelf break, these variations intensified southward and reached a maximum in front of the DIS. There, the mCDW volume was ∼8,000km3 in 2007, rapidly decreased to 4,700km3 in 2014 before rebounding to 7,300km3 in 2018. We find that such interannual variability is coherent with local Ekman pumping integrated along the DGT modulated by the presence of sea ice, and complementing earlier theories involving shelf break winds only. The interannual variability in strength of the dominant south-southeast coastal wind modulates the amplitude of Ekman upwelling along the eastern boundary of the Amundsen Sea polynya during the austral summers of the surveyed years, apparently leading to change in the volume of mCDW along the DGT. We note a strong correlation between the wind variability and the longitudinal location of the Amundsen Sea Low. © 2021. The Authors.
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| 30. |
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| 31. |
- Korlén, S., et al.
(författare)
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Leaders as intermediates between economic incentive models and professional motivation
- 2018
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Ingår i: Läkartidningen. - : Swedish Medical Association. - 0023-7205 .- 1652-7518. ; 115:22-23
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Tidskriftsartikel (refereegranskat)abstract
- The application of economic incentives to providers in health care governance is debated. Advocates argue that it drives efficiency and improvement, opponents claim that it leads to unintended consequences for patients and professionals. Research shows that incentives can increase well-defined activities and targets, but there is a lack of substantial evidence that applications in health care lead to desired outcomes. The motivational literature acknowledges internal sources of motivation as important determinants of behavior, and the literature about professions suggests that professional values of serving patient needs is a key motivator. The management literature identifies the important role of leaders in aligning external demands and rewards to staff preferences, using their own management and leadership skills. Findings in health services research confirm the vital role of leaders for successful implementation and improvement work. In sum, internal motivators and the role of leaders are important to acknowledge also when understanding how economic governance models are put into practice. Our recently published qualitative case study provides empirical examples of how clinical leaders function as intermediaries between a local care choice model, including financial incentives, and the motivation of staff. The strategies deployed by the leaders aimed to align the economic logics of the model to the professional focus on increasing patient value. The main conclusion from these empirical examples, as well as previous research, is that health care managers play a key role in aligning economic incentive models with professional values and in translating such models in to feasible tasks related to the provision of high quality care.
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| 32. |
- Kro, G A B, et al.
(författare)
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A new tool for the validation of umbilical cord acid-base data.
- 2010
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Ingår i: BJOG : an international journal of obstetrics and gynaecology. - : Wiley. - 1471-0528 .- 1470-0328. ; 117:12, s. 1544-52
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Tidskriftsartikel (refereegranskat)abstract
- To identify the distribution of carbon dioxide tension (pCO(2) ) relative to pH in validated umbilical cord acid-base data.
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| 33. |
- La, H. S., et al.
(författare)
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Zooplankton and micronekton respond to climate fluctuations in the Amundsen Sea polynya, Antarctica
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- The vertical migration of zooplankton and micronekton (hereafter 'zooplankton') has ramifications throughout the food web. Here, we present the first evidence that climate fluctuations affect the vertical migration of zooplankton in the Southern Ocean, based on multi-year acoustic backscatter data from one of the deep troughs in the Amundsen Sea, Antarctica. High net primary productivity (NPP) and the annual variation in seasonal ice cover make the Amundsen Sea coastal polynya an ideal site in which to examine how zooplankton behavior responds to climate fluctuations. Our observations show that the timing of the seasonal vertical migration and abundance of zooplankton in the seasonally varying sea ice is correlated with the Southern Annular Mode (SAM) and El Nino Southern Oscillation (ENSO). Zooplankton in this region migrate seasonally and overwinter at depth, returning to the surface in spring. During +SAM/La Nina periods, the at-depth overwintering period is shorter compared to -SAM/El Nino periods, and return to the surface layers starts earlier in the year. These differences may result from the higher sea ice cover and decreased NPP during +SAM/La Nina periods. This observation points to a new link between global climate fluctuations and the polar marine food web.
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| 34. |
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| 35. |
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| 36. |
- Lundin, Rolf A, et al.
(författare)
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Projectification Revisited/Revised
- 2015
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The original notion of projectification related to organizations and project management was straightforward. Activities formerly regarded or handled as normal matters or routines were transformed to be projects with a specific task associated with each project and a focus on efficiency in terms of time lapse and resources. However, over time the notion has appeared in a wide set of narratives.In this paper we provide examples of narratives intending to pave the way for an academic discussion aiming towards theorizing projectification processes. We include evidence of a need to see beyond the simplistic notions and also allude to meta-theory.
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| 37. |
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| 38. |
- Mazur, Aleksandra, 1983, et al.
(författare)
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An object-based SAR image iceberg detection algorithm applied to the Amundsen Sea
- 2017
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Ingår i: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257. ; 189, s. 67-83
-
Tidskriftsartikel (refereegranskat)abstract
- © 2016 The AuthorsAn object-based method for automatic iceberg detection from Advanced Synthetic Aperture Radar (ASAR) images has been developed and applied in the Amundsen Sea, Antarctica. The automatic identification is based on brightness and spatial parameters of the ASAR images at five scale levels, and was verified with manual classification in four areas chosen to represent varying environmental conditions. The presented algorithm works comparatively well with images of the ocean in freezing temperatures and strong wind conditions, common in the Amundsen Sea. The detection rate was 96.2% which corresponds to 93.2% of the icebergs area, for all seasons. The algorithm generated 3.8% errors in the form of ‘misses’ and 7.0% of ‘false alarms’, mainly caused by the presence of ice floes. The method was applied on 432 radar images acquired in 2011 under different meteorological, oceanographic and sea ice conditions. As an output a map showing the probability of finding icebergs has been created. It shows that high probability coincides with depth contours and indicates a westward drift of the bergs throughout the whole region.
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| 39. |
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| 40. |
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| 41. |
- Nilsing Strid, Emma, 1973-, et al.
(författare)
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A physiotherapy perspective on patient injuries : Learning from incident reporting
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: Patient adverse events such as accidental falls are still common in healthcare, putting not only patients but also healthcare workers (HCWs) at risk for injuries. The causes are often multifactorial and many can be predicted and prevented. However, the effectiveness of preventive programs varies, which emphasizes the need to better understand the factors that increase the risk of falls to inform intervention strategies. Learning from incident reports is one core strategy to develop a culture of safety for both patients and HCWs, but research from a physiotherapy perspective is scarce.Purpose: The aim of this retrospective study was to examine patient injuries reported over a 4-year period, and to further explore patient falls regarding situations and contributory factors putting patients at risk for fall.Methods: The Patient and Workers Safety Study (PAWSS) was conducted in a County Council of eastern Sweden, focusing on patients and HCWs injuries over a 4-year period. Data was retrieved from the Incident reporting systems during 2011-2014. This part of the study included 11006 incident reports of risks and patient injuries.Results: The majority of the 11006 reported incidents were related to medication errors, 23%, followed by incidents occurred in care processes, 22%. Patients were in mean 65 years old, 55% were women and 45% men. There was a decline in frequency of reported incidents during the four years, from 3010 incidents in 2011 to 2201 in 2014. Patient falls were reported in 17% of all incidents (n=1861), most common in care processes. These patients were in mean 78 years old, and the majority male (52%). Patients were more likely to fall in un-witnessed situations (92%), primarily when going to the toilet (25%) or just found on the floor (16%). In 8% of the fall incidents, patients were assisted by a HCW, a situation where some HCWs were injured. Contributing factors to the fall were reported in approximately 40% of the incidents. Impaired balance or muscle strength were most common (42%) followed by cognitive impairments (21%). In a few incidents, factors related to the organization, technology/tools or environment were reported as contributing to the fall. Fifteen percent of the fall incidents required treatment, and 1% resulted in death.Conclusions: Patient falls are common adverse events. Patients are more likely to fall when unassisted, and impaired balance and muscle strength are major contributing factors to patient falls. These are known risk factors which can be assessed and targeted in a fall prevention programvof which physiotherapists can play an important role. Whether a fall prevention program incorporating physiotherapists in a human factor system approach increases patient and workers safety needs to be further investigated.Implications: Incident reports capture information that provides a learning opportunity by identifying injury risk factors. The results from this study highlight patient falls as harmful for both patients and HCWs. By providing assessments of functioning, risks and tailored interventions, physiotherapists at different healthcare settings, wards and teams may play an important role in safe patient handling for both patients and HCWs.
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| 42. |
- Olivo, G., et al.
(författare)
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Immediate effects of a single session of physical exercise on cognition and cerebral blood flow: A randomized controlled study of older adults
- 2021
-
Ingår i: Neuroimage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 225
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Regular physical activity is beneficial for cognitive performance in older age. A single bout of aerobic physical exercise can transiently improve cognitive performance. Researchers have advanced improvements in cerebral circulation as a mediator of long-term effects of aerobic physical exercise on cognition, but the immediate effects of exercise on cognition and cerebral perfusion are not well characterized and the effects in older adults are largely unknown. Methods: Forty-nine older adults were randomized to a 30-min aerobic exercise at moderate intensity or relaxation. Groups were matched on age and cardiovascular fitness (VO2 max). Average Grey Matter Blood Flow (GMBF), measured by a pulsed arterial-spin labeling (pASL) magnetic resonance imaging (MRI) acquisition, and working memory performance, measured by figurative n-back tasks with increasing loads were assessed before and 7 min after exercising/resting. Results: Accuracy on the n-back task increased from before to after exercising/resting regardless of the type of activity. GMBF decreased after exercise, relative to the control (resting) group. In the exercise group, higher n-back performance after exercise was associated with lower GMBF in the right hippocampus, left medial frontal cortex and right orbitofrontal cortex, and higher cardiovascular fitness was associated with lower GMBF. Conclusion: The decrease of GMBF reported in younger adults shortly after exercise also occurs in older adults and relates to cardiovascular fitness, potentially supporting the link between cardiovascular fitness and cerebrovascular reactivity in older age.
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| 43. |
- Peleli, Maria, et al.
(författare)
-
Renal denervation attenuates NADPH oxidase-mediated oxidative stress and hypertension in rats with hydronephrosis
- 2016
-
Ingår i: American Journal of Physiology - Renal Physiology. - : American Physiological Society. - 0363-6127 .- 1522-1466 .- 1931-857X. ; 310:1, s. F43-F56
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Tidskriftsartikel (refereegranskat)abstract
- Hydronephrosis is associated with development of salt-sensitive hypertension. Studies suggest that increased sympathetic nerve activity (SNA) and oxidative stress play important roles in renovascular hypertension. This study aimed to investigate the link between renal SNA and NADPH oxidase (NOX) regulation in the development of hypertension in rats with hydronephrosis. Hydronephrosis was induced by partial unilateral ureteral obstruction (PUUO) in young rats. Sham surgery or renal denervation was performed at the same time. Blood pressure was measured during normal, high and low salt diets. Renal excretion pattern, NOX activity and expression, as well as components of RAAS were characterized. On normal salt diet, PUUO rats had elevated blood pressure compared with controls (115±3 vs 87±1 mmHg), and displayed increased urine production and lower urine osmolality. Blood pressure change in response to salt loading (salt-sensitivity) was more pronounced in the PUUO group compared with controls (15±2 vs 5±1mmHg). Renal denervation in PUUO rats attenuated hypertension (97±3mmHg) and salt-sensitivity (5±1mmHg), and normalized renal excretion pattern, whereas the degree of renal fibrosis and inflammation was not changed. NOX activity and expression, as well as renin and AT1A receptor expression, were increased in renal cortex from PUUO rats, and normalized by denervation. Plasma sodium and potassium levels were elevated in PUUO rats and normalized after renal denervation. Denervation in PUUO rats was also associated with reduced NOX expression, superoxide production and fibrosis in the heart. This study emphasizes a link between renal nerves, NOX function, and development of hypertension.
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| 44. |
- Rebesco, M., et al.
(författare)
-
Quaternary contourite drifts of the Western Spitsbergen margin
- 2013
-
Ingår i: Deep-Sea Research Part I-Oceanographic Research Papers. - : Elsevier BV. - 0967-0637. ; 79, s. 156-168
-
Tidskriftsartikel (refereegranskat)abstract
- The study of contourite drifts is an increasingly used tool for understanding the climate history of the oceans. In this paper we analyse two contourite drifts along the continental margin west of Spitsbergen, just south of the Fram Strait where significant water mass exchanges impact the Arctic climate. We detail the internal geometry and the morphologic characteristics of the two drifts on the base of multichannel seismic reflection data, sub-bottom profiles and bathymetry. These mounded features, that we propose to name Isfjorden and Bellsund drifts, are located on the continental slope between 1200 and 1800 m depth, whereas the upper slope is characterized by reduced- or non-deposition. The more distinct Isfjorden Drift is about 25 km wide and 45 km long, and over 200 ms TWT thick. We revise the 13 years-long time series of velocity, temperature, and salinity obtained from a mooring array across the Fram Strait. Two distinct current cores are visible in the long-term average. The shallower current core has an average northward velocity of about 20 cm/s, while the deeper bottom current core at about 1450 m depth has an average northward velocity of about 9 cm/s. We consider Norwegian Sea Deep Water episodically ventilated by relatively dense and turbid shelf water from the Barents Sea responsible for the accumulation of the contourites. The onset of the drift growth west of Spitsbergen is inferred to be about 1.3 Ma and related to the Early Pleistocene glacial expansion recorded in the area. The lack of mounded contouritic deposits on the continental slope of the Storfjorden is related to consecutive erosion by glacigenic debris flows. The Isfjorden and Bellsund drifts are inferred to contain the record of the regional palaeoceanography and glacial history and may constitute an excellent target of future scientific drilling. (C) 2013 Elsevier Ltd. All rights reserved.
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| 45. |
- Salami, Alireza, et al.
(författare)
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Dopamine D-2/3 Binding Potential Modulates Neural Signatures of Working Memory in a Load-Dependent Fashion
- 2019
-
Ingår i: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 39:3, s. 537-547
-
Tidskriftsartikel (refereegranskat)abstract
- Dopamine (DA) modulates corticostriatal connections. Studies in which imaging of the DA system is integrated with functional imaging during cognitive performance have yielded mixed findings. Some work has shown a link between striatal DA(measured by PET) and fMRI activations, whereas others have failed to observe such a relationship. One possible reason for these discrepant findings is differences in task demands, such that a more demanding task with greater prefrontal activations may yield a stronger association with DA. Moreover, a potential DA-BOLD association may be modulated by task performance. We studied 155 (104 normal-performing and 51 low-performing) healthy older adults (43% females) who underwent fMRI scanning while performing a working memory (WM) n-back task along with DA D-2/3 PET assessment using [C-11] raclopride. Using multivariate partial-least-squares analysis, we observed a significant pattern revealing positive associations of striatal as well as extrastriatal DA D-2/3 receptors to BOLD response in the thalamo-striatalcortical circuit, which supports WM functioning. Critically, the DA-BOLD association in normal-performing, but not low-performing, individuals was expressed in a load-dependent fashion, with stronger associations during 3-back than 1-/2-back conditions. Moreover, normal-performing adults expressing upregulated BOLD in response to increasing task demands showed a stronger DA-BOLD association during 3-back, whereas low-performing individuals expressed a stronger association during 2-back conditions. This pattern suggests a nonlinear DA-BOLD performance association, with the strongest link at the maximum capacity level. Together, our results suggest that DA may have a stronger impact on functional brain responses during more demanding cognitive tasks.
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| 46. |
- Schofield, O., et al.
(författare)
-
Moving Towards Implementation of a Southern Ocean Observing System
- 2016
-
Ingår i: Marine Technology Society Journal. - 0025-3324. ; 50:3, s. 63-68
-
Tidskriftsartikel (refereegranskat)abstract
- The Global Ocean Observing System (GOOS) is deploying a holistic system to monitor the worlds ocean; however, a major challenge is many regions are chronically under-sampled. One such region is the Southern Ocean, which is remote and a harsh region to sample. The importance of improving holistic sampling in this region is clear, given its disproportionate significance to Earth and the fact that the area is exhibiting rapid change. As the Southern Ocean is beyond the capability of any single nation, the international Southern Ocean research community recognized a need for improved international coordination, strategic planning, and eventual implementation of a Southern Ocean Observing System (SOOS). The focus of SOOS is on (1) designing a sustainable system that provides data for determining the status and change of the Southern Ocean, (2) standardizing measurements across national efforts, (3) providing a forum for opportunities to guide future investments, (4) developing a portal for open transparent access to data, and (5) supporting grassroots discussion to identify/design expeditions and technology development. This manuscript highlights current SOOS strategies to meet those needs. Critical lessons emphasize the need for providing value to users who are contributing content/strategy as volunteers and sustain a dedicated office to coordinate those efforts while providing documented value to those contributing time and expertise.
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| 47. |
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| 48. |
- Wåhlin, Anna, 1970, et al.
(författare)
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Horizontal convection in water heated by infrared radiation and cooled by evaporation : scaling analysis and experimental results
- 2010
-
Ingår i: Tellus. Series A, Dynamic meteorology and oceanography. - : Stockholm University Press. - 0280-6495 .- 1600-0870. ; 62:2, s. 154-169
-
Tidskriftsartikel (refereegranskat)abstract
- An experimental study of horizontal convection with a free surface has been conducted. Fresh water was heated from above by an infrared lamp placed at one end of a tank, and cooled by evaporation as the water moved away from the heat source. The heat radiated from the lamp was absorbed in a thin (less than 1 mm) layer next to the surface, and then advected and diffused away from the lamp region. Latent heat loss dominated the surface cooling processes and accounted for at least 80% of the energy loss. The velocity and temperature fields were recorded with PIV technology, thermometers and an infrared camera. In similarity with previous horizontal convection experiments the measurements showed a closed circulation with a gradually cooling surface current moving away from the lamp. Below the surface current the water was stably stratified with a comparatively thick and slow return current. The thickness and speed, and hence the mass transport, of the surface- and the return current increased with distance from the lamp. The latent cooling at the free surface gives a heat flux which increases with the temperature difference between the surface water and the air above it. Hence the surface temperature relaxes towards an equilibrium value, for which the heat flux is zero. The main new result is a scaling law, taking into account this relaxation boundary condition for the surface temperature. The new scaling includes a (relaxation) length scale for the surface temperature, equivalent to the distance the surface current travels before it has lost the heat that was gained underneath the lamp. The length scale increases with the forcing strength and the (molecular) thermal diffusivity but decreases with the strength of the relaxation. Numerical simulations of this problem for a shallow tank have also been performed. The velocity and temperature in the laboratory and numerical experiments agree with the scaling laws in the upper part of the tank, but not in the lower.
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| 49. |
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| 50. |
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