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- Callaghan, Terry V., et al.
(författare)
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A new climate era in the sub-Arctic : Accelerating climate changes and multiple impacts
- 2010
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 37:14, s. L14705-
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Tidskriftsartikel (refereegranskat)abstract
- Climate warming in the Swedish sub-Arctic since 2000 has reached a level at which statistical analysis shows for the first time that current warming has exceeded that in the late 1930' s and early 1940' s, and has significantly crossed the 0 degrees C mean annual temperature threshold which causes many cryospheric and ecological impacts. The accelerating temperature increase trend has driven similar trends in the century-long increase in snow thickness, loss of lake ice, increases in active layer thickness, lake water TOC (total organic carbon) concentrations and the assemblages of diatoms, and changes in tree-line location and plant community structure. Some of these impacts were not evident in the first warm period of the 20th Century. Changes in climate are associated with reduced temperature variability, particularly loss of cold winters and cool summers, and an increase in extreme precipitation events that cause mountain slope instability and infrastructure failure. The long term records of multiple, local environmental factors compiled here for the first time provide detailed information for adaptation strategy development while dramatic changes in an environment particularly vulnerable to climate change highlight the need to adopt global mitigation strategies.
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| 4. |
- Moen, V, et al.
(författare)
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Hyponatremia complicating labour-rare or unrecognised? A prospective observational study
- 2009
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Ingår i: BJOG-AN INTERNATIONAL JOURNAL OF OBSTETRICS AND GYNAECOLOGY. - : Wiley. - 1470-0328 .- 1471-0528. ; 116:4, s. 552-561
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the occurrence of hyponatraemia following delivery, with a hypothesis that hyponatraemia has a high prevalence in labouring women. Prospective observational study. Consultant-led delivery suite in County Hospital, Kalmar, Sweden. A total of 287 pregnant women at term (37 full gestational weeks). Oral fluids were allowed during labour. Blood samples were collected on admission, after delivery, and from the umbilical artery and vein. Hyponatraemia defined as plasma sodium <= 130 mmol/l after delivery. Hyponatraemia was found in 16 (26%) of the 61 mothers who received more than 2500 ml of fluid during labour. Two-thirds of fluids were orally ingested. Decrease in plasma sodium concentration during labour correlated with duration of labour and the total fluid volume administered. Analysis by multivariate logistic regression showed that hyponatraemia was significantly correlated with fluid volume (P < 0.001) but not with oxytocin administration or epidural analgesia. Hyponatraemia correlated significantly with prolonged second stage of labour, instrumental delivery, and emergency caesarean section for failure to progress (P = 0.002). Hyponatraemia is not uncommon following labour. Tolerance to a water load is diminished during labour; therefore, even moderate fluid volumes may cause hyponatraemia. Women should not be encouraged to drink excessively during labour. Oral fluids, when permitted, should be recorded, and intravenous administration of hypotonic fluids should be avoided. When abundant drinking is unrecognised or intravenous fluid administration liberal, life-threatening hyponatraemia may develop. The possibility that hyponatraemia may influence uterine contractility merits further investigation.
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| 7. |
- Wennmalm, Stefan, et al.
(författare)
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Interferometry and fluorescence detection for simultaneous analysis of labeled and unlabeled nanoparticles in solution
- 2012
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 134:48, s. 19516-19519
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Tidskriftsartikel (refereegranskat)abstract
- A novel fluctuation spectroscopy technique based on interferometry is described. The technique, termed scattering interference correlation spectroscopy (SICS), autocorrelates the signals from the forward-scattered and transmitted laser light from nanoparticles (NPs) in solution. SICS has two important features: First, for unlabeled NPs with known refractive index, it analyzes not only the diffusion coefficient but also the effective cross section and concentration in a single measurement. Second, it can be combined with fluorescence correlation spectroscopy (FCS) for simultaneous analysis of labeled and unlabeled NPs. SICS is here demonstrated on unlabeled M13 phages and on unlabeled NPs with diameters of 210 nm down to 26 nm. It is also shown how the combination of SICS and FCS can be used to determine the fraction of fluorescent NPs in a mixture and estimate Kd from a single binding measurement.
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| 8. |
- Da Silva, Adrien
(författare)
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Aspects of material and heat transfer in drop- and powder-based laser additive manufacturing
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Additive Manufacturing became a major research topic and part of industrial production in the past years. Numerous techniques now allow to build 3D structures with a wide choice of materials. When it comes to processing of metals, a laser beam is often used as a heat source to melt either a wire or powder. Novel approaches of material deposition are also developed, such as Laser Droplet Generation, which could potentially be applied to Additive Manufacturing. During the process, the laser beam light is partly absorbed by the material, and is then converted to heat, which can induce melting and even vaporization. Additive Manufacturing presents several processing challenges, such as the recoil pressure acting on the drops and powder particles that affects their trajectory. Storage and recycling of the powders is also an important aspect since the powder properties are changed through aging. Another challenge is the adjustment of process parameters according to varying deposition conditions, where the use of process monitoring techniques is crucial.Therefore, this thesis aims at better understanding (i) the effects of recoil pressureon metal drops and powder particles, (ii) powder aging and its effects on the process, and (iii) process optimisation and stability via monitoring. In the six adjoined papers, high-speed imaging and thermal imaging were used to observe laser Additive Manufacturing processes involving both metal drops and powders. The videos enabled to observe drop detachments, measure trajectories, plot powder density maps, quantify powder catchment in the melt pool, measure themelt pool geometry, detect oxides, and extract cooling rates. The experimental results were supplemented with material analysis and theoretical calculations of thermodynamics, recoil pressure and surface tension.These studies allowed to conclude that the recoil pressure induced by laser irradiation on a drop or a powder particle can have some significant effect such as acceleration, change of trajectory, or disintegration. However, these effects seem to be considerably lower than what theoretical models predict. It was also found that the recoil pressure can be used to accurately detach drops from a wire, which was utilised as a new material deposition method for Additive Manufacturing. In Directed Energy deposition, it was showed that aging of the aluminium powder feedstock should be avoided since it induces high porosity, high dilution and decreased mechanical properties. Finally, to guarantee a defect-free deposition during the whole process, it was demonstrated that a thermal camera can be used to monitor the melt pool size, which allows to apply appropriate laser power adjustments to compensate for changing building conditions.
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| 9. |
- Hultström, Michael, 1978-
(författare)
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Neurohormonal interactions on the renal oxygen delivery and consumption in haemorrhagic shock-induced acute kidney injury
- 2013
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Ingår i: Acta Physiologica. - : Wiley. - 1748-1708 .- 1748-1716. ; 209:1, s. 11-25
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Forskningsöversikt (refereegranskat)abstract
- Haemorrhagic shock is a common cause of acute kidney injury, which is a major risk factor for developing chronic kidney disease. The mechanism is superficially straightforward. An arterial pressure below the kidney's autoregulatory region leads to a direct reduction in filtration pressure and perfusion, which in turn cause renal failure with reduced glomerular filtration rate (GFR), and AKI because of hypoxia. However, the kidney's situation is further worsened by the hormonal and neural reactions to reduced perfusion pressure. There are three major systems working to maintain arterial pressure in shock: Sympathetic signaling, the renin-angiotensin-system, and vasopressin. These work to retain electrolytes and water, and to increase peripheral resistance and cardiac output. In the kidney the increased electrolyte reabsorption consumes oxygen. At the same time, at the signaling level seen in shock, all of these hormones reduces renal perfusion, and thereby oxygen delivery. This creates an exaggerated hypoxic situation that is liable to worsen the AKI. The present review will examine this mechanistic background and identify a number of areas that require further studies. At this time the ideal treatment of haemorrhagic shock appears to be slow fluid resuscitation, possibly with hyperosmolar sodium, low chloride, and no artificial colloids. From the standpoint of the kidney, renin-angiotensin system inhibitors appear fruitful for further study.
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