| 1. |
- Ydenius, Anders, et al.
(author)
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Fatal car to moose collisions : Real-world in-depth data, crash tests and potential of different countermeasures
- 2017
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In: Proceedings 25th International Technical Conference on the Enhanced Safety of Vehicles (ESV). - : NHTSA.
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Conference paper (peer-reviewed)abstract
- Vehicle collisions with large animals constitute a high risk of serious or fatal injuries, for example in northern America, Europe and Japan. In Sweden approximately 5,000 car collisions with moose occur annually. The change of velocity and acceleration is in general very low, but the car structure is not designed for collision with large animals at high speed. The objectives were to evaluate occupant response and vehicle structure in crash tests; to investigate the factors involved in real-world fatal crashes in Sweden; and to evaluate the potential of Autonomous Emergency Braking (AEB) to increase moose car collision avoidance and survivability. Five crash tests were conducted with cars with different size and characteristics, such as glass and sun roof. A moose crash dummy was impacted at 70 km/h. The Swedish Transport Administration (STA) national database of fatal collisions was used to study fatalities (n=47) in collisions with moose during the period 2005-2016. The analysis focused on collisions where the primary cause of fatality was the collision with a moose. The crash tests showed that a moose collision could be survivable at 70 km/h with an acceptable distance to the header structure. None of the tested cars had an intrusion by the moose into the occupant compartment. The results of the in-depth data analysis showed that a critical factor for a fatal injury was whether the roof was partly or completely ripped off. Downward deformation of the front header structure was also critical together with Apillar deformation. In 24% of the accidents the moose was partly or completely trapped inside the occupant compartment. In 90% of the fatal collisions it was darkness or twilight. In more than 85% of the collisions, no evidence of braking could be detected prior to collision. All of the collisions occurred on rural roads and 83% of the fatalities occurred on roads with speed limits of 90 km/h or above. In eight accident scenes there were moose fences to prevent the moose to access the road. In those accidents, however, the fence was either damaged or had open sections. The analysis of road-side area showed that in many of the moose accidents the side view was enough to allow detection of the moose by an AEB sensor. A critical issue is the ability of the sensors to detect the moose in darkness. The study of the potential for AEB with moose detection was conducted under the assumption that night vision sensors are available, such as infrared sensors or light amplifying technique. With a threshold of 70 km/h for car-moose collision survivability, the results of the analysis showed that AEB had a potential to save (~40%) 18 out of 47 lives. It is suggested that road fencing is preferable on roads with speed limits above 90 km/h, and below 100 km/h, moose AEB has a potential to avoid fatal moose crashes.
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| 2. |
- Engström, Anders, 1982-
(author)
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Aerosol-cloud interaction from an observational and modeling perspective
- 2011
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Doctoral thesis (other academic/artistic)abstract
- Clouds may respond strongly to changes in the atmospheric aerosol population, and the response of clouds to an increased global aerosol burden could to some extent mask the warming caused by enhanced greenhouse gas concentrations. However, estimates of the impact of aerosols on cloud properties are associated with large uncertainties, both because of difficulties representing the aerosol-cloud interaction within models, and because of problems of unequivocally isolating the effect of aerosols on cloud properties in observational data. This thesis focuses in part on underlying meteorological factors that significantly correlate with both aerosol and cloud properties, and on how sensitive clouds are to small variations in meteorological conditions. It was found that meteorological covariations must be taken into account when estimating the strength of the relationship between aerosols and cloud properties. By studying the response of shallow convective clouds to perturbations in meteorological conditions and aerosol concentration, it was further concluded that variations in meteorological conditions can enhance or mask the relationship between aerosols and cloud properties, making it difficult to isolate the aerosol signature from small meteorological differences. Additionally, the impact of deep convective clouds on the redistribution of aerosols within a cloud life cycle is examined. It was found that mid-tropospheric aerosols can have a substantial source in evaporating cloud droplets within deep convection. Lastly, this thesis focuses on the implications of meteorological analysis uncertainties, in part related to the difficulties of constraining meteorological variability in observational data of clouds and aerosols, but mainly the impact of analysis errors on atmospheric trajectory calculations. A method is presented to consistently estimate the uncertainty in trajectory calculations. It was concluded that the spatial and temporal trajectory error can be substantially underestimated if the analysis error is not taken into account.
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| 3. |
- Engström, Anders, 1982-, et al.
(author)
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Estimating trajectory uncertainties due to flow dependent errors in the atmospheric analysis
- 2009
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In: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 9:22, s. 8857-8867
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Journal article (peer-reviewed)abstract
- The uncertainty of a calculated trajectory is dependent on the uncertainty in the atmospheric analysis. Using the Ensemble Transform method (originally adapted for ensemble forecasting) we sample the analysis uncertainty in order to create an ensemble of analyses where a trajectory is started from each perturbed analysis. This method, called the Ensemble analysis method (EA), is compared to the Initial spread method (IS), where the trajectory receptor point is perturbed in the horizontal and vertical direction to create a set of trajectories used to estimate the trajectory uncertainty. The deviation growth is examined for one summer and one winter month and for 15 different geographical locations. We find up to a 40% increase in trajectory deviation in the mid-latitudes using the EA method. A simple model for trajectory deviation growth speed is set up and validated. It is shown that the EA method result in a faster error growth compared to the IS method. In addition, two case studies are examined to qualitatively illustrate how the flow dependent analysis uncertainty can impact the trajectory calculations. We find a more irregular behavior for the EA trajectories compared to the IS trajectories and a significantly increased uncertainty in the trajectory origin. We conclude that by perturbing the analysis in agreement with the analysis uncertainties the error in backward trajectory calculations can be more consistently estimated.
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| 4. |
- Engström, Anders, 1982-, et al.
(author)
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Modeled response in radiative properties of isolated shallow convective clouds due to perturbations in meteorological state variables and atmospheric aerosol loading
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Other publication (other academic/artistic)abstract
- The aim of the present study is to estimate the range of variability in observational data of meteorological variables permitted to determine a clear and unambiguous signal in cloud fraction and cloud albedo due to changes in aerosol concentrations. Three different cases of tropical shallow convection have been simulated using a two-dimensional cloud resolving model with aerosol-cloud interactions. For each case, 30 different small perturbations were added to the initial meteorological profiles of zonal wind, potential temperature and specific humidity. For each meteorological per- turbation an additional 14 simulations were performed with different boundary layer accumulation mode aerosol concentrations ranging from clean (50 cm-3) to polluted (1350 cm-3) conditions. A total of 5040 simulations were performed to elucidate the impact of aerosols on the simulated cloud fraction and cloud albedo and to compare this to the corresponding impact to the influence of small meteorological perturbations. For the simulated cases, we find that for cloud fraction, the aerosol signal is in general much weaker than the change due to small changes in meteorology. This was especially true for parameters that influence the relative humidity of the environment, i.e. tempera- ture and specific humidity. For cloud albedo, the aerosol signal surpasses that of the relatively small meteorological perturbations. We find up to 40% difference in cloud albedo going from clean to polluted conditions. The corresponding maximum change due to the meteorological perturbations was only 14%. We conclude that for the simulated shallow convective clouds, isolating an aerosol effect on cloud fraction is not possible if using meteorological analysis data containing errors of the same order of magnitude as the imposed meteorological perturbations. However, the meteorological constraints may be sufficient to isolate an aerosol effect on cloud albedo.
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| 5. |
- Engström, Emma, 1982-, et al.
(author)
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Applying spatial regression to evaluate risk factors for microbiological contamination of urban groundwater sources in Juba, South Sudan
- 2017
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In: Hydrogeology Journal. - : Springer Verlag. - 1431-2174 .- 1435-0157. ; 25:4, s. 1077-1091
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Journal article (peer-reviewed)abstract
- This study developed methodology for statistically assessing groundwater contamination mechanisms. It focused on microbial water pollution in low-income regions. Risk factors for faecal contamination of groundwater-fed drinking-water sources were evaluated in a case study in Juba, South Sudan. The study was based on counts of thermotolerant coliforms in water samples from 129 sources, collected by the humanitarian aid organisation Médecins Sans Frontières in 2010. The factors included hydrogeological settings, land use and socio-economic characteristics. The results showed that the residuals of a conventional probit regression model had a significant positive spatial autocorrelation (Moran’s I = 3.05, I-stat = 9.28); therefore, a spatial model was developed that had better goodness-of-fit to the observations. The most significant factor in this model (p-value 0.005) was the distance from a water source to the nearest Tukul area, an area with informal settlements that lack sanitation services. It is thus recommended that future remediation and monitoring efforts in the city be concentrated in such low-income regions. The spatial model differed from the conventional approach: in contrast with the latter case, lowland topography was not significant at the 5% level, as the p-value was 0.074 in the spatial model and 0.040 in the traditional model. This study showed that statistical risk-factor assessments of groundwater contamination need to consider spatial interactions when the water sources are located close to each other. Future studies might further investigate the cut-off distance that reflects spatial autocorrelation. Particularly, these results advise research on urban groundwater quality. © 2016, The Author(s).
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| 6. |
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| 7. |
- Hellman, Urban, 1966-, et al.
(author)
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Presence of hyaluronan in lung alveoli in severe Covid-19 : an opening for new treatment options?
- 2020
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In: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 295:45, s. 15418-15422
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Journal article (peer-reviewed)abstract
- Severe corona virus disease 2019 (Covid-19) is characterized by inflammation of the lungs with increasing respiratory impairment. In fatal Covid-19, lungs at autopsy have been filled with a clear liquid jelly. However, the nature of this finding has not yet been determined.The aim of the study was to demonstrate if the lungs of fatal Covid-19 contain hyaluronan as it is associated with inflammation and acute respiratory distress syndrome (ARDS) and may have the appearance of liquid jelly.Lung tissue obtained at autopsy from three deceased Covid-19 patients was processed for hyaluronan histochemistry using a direct staining method and compared with staining in normal lung tissue.Stainings confirmed that hyaluronan is obstructing alveoli with presence in exudate and plugs, as well as in thickened perialveolar interstitium. In contrast, normal lungs only showed hyaluronan in intact alveolar walls and perivascular tissue. This is the first study to confirm prominent hyaluronan exudates in the alveolar spaces of Covid-19 lungs, supporting the notion that the macromolecule is involved in ARDS caused by SARS-CoV-2. The present finding may open up for new treatment options in severe Covid-19, aiming at reducing the presence and production of hyaluronan in the lungs.
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| 8. |
- Kullgren, Anders, 1963, et al.
(author)
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The potential of vehicle and road infrastructure interventions in fatal bicyclist accidents on Swedish roads—What can in-depth studies tell us?
- 2019
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In: Traffic Injury Prevention. - : Informa UK Limited. - 1538-9588 .- 1538-957X. ; 20:sup1, s. S7-S12
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Journal article (peer-reviewed)abstract
- Objective: The objective of this article is to describe the characteristics of fatal crashes with bicyclists on Swedish roads in rural and urban areas and to investigate the potential of bicycle helmets and different vehicle and road infrastructure interventions to prevent them. The study has a comprehensive approach to provide road authorities and vehicle manufacturers with recommendations for future priorities. Methods: The Swedish Transport Administration’s (STA) in-depth database of fatal crashes was used for case-by-case analysis of fatal cycling accidents (2006–2016) on rural (n = 82) and urban (n = 102) roads. The database consists of information from the police, medical journals, autopsy reports, accident analyses performed by STA, and witness statements. The potential of helmet use and various vehicle and road infrastructure safety interventions was determined retrospectively for each case by analyzing the chain of events leading to the fatality. The potential of vehicle safety countermeasures was analyzed based on prognoses on their implementation rates in the Swedish vehicle fleet. Results: The most common accident scenario on rural roads was that the bicyclist was struck while cycling along the side of the road. On urban roads, the majority of accidents occurred in intersections. Most accidents involved a passenger car, but heavy trucks were also common, especially in urban areas. Most accidents occurred in daylight conditions (73%). Almost half (46%) of nonhelmeted bicyclists would have survived with a helmet. It was assessed that nearly 60% of the fatal accidents could be addressed by advanced vehicle safety technologies, especially autonomous emergency braking with the ability to detect bicyclists. With regard to interventions in the road infrastructure, separated paths for bicyclists and bicycle crossings with speed calming measures were found to have the greatest safety potential. Results indicated that 91% of fatally injured bicyclists could potentially be saved with known techniques. However, it will take a long time for such technologies to be widespread. Conclusions: The majority of fatally injured bicyclists studied could potentially be saved with known techniques. A speedy implementation of important vehicle safety systems is recommended. A fast introduction of effective interventions in the road infrastructure is also necessary, preferably with a plan for prioritization.
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| 9. |
- Löfqvist, Chatarina, 1964, et al.
(author)
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Association of Retinopathy of Prematurity With Low Levels of Arachidonic Acid A Secondary Analysis of a Randomized Clinical Trial
- 2018
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In: Jama Ophthalmology. - : American Medical Association (AMA). - 2168-6165. ; 136:3, s. 271-277
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Journal article (peer-reviewed)abstract
- IMPORTANCE Mice with oxygen-induced retinopathy fed matched diets except for omega-3 long-chain polyunsaturated fatty acids (LC-PUFAs) vs omega-6 LC-PUFAs demonstrate relative antiangiogenic and neuroprotective associations of omega-3 LC-PUFAs. However, supplementing preterm infants with LC-PUFAs has been inconsistent in reducing major preterm morbidities. However, few studies measured serum lipid levels after supplementation. OBJECTIVE To examine the associated risk of retinopathy of prematurity (ROP) from the levels of circulating omega-3 and omega-6 LC-PUFAs. DESIGN, SETTING, AND PARTICIPANTS This longitudinal clinical study was a further analysis of serum lipid levels from a randomized controlled trial cohort of 90 infants born at gestational age (GA) less than 28 weeks. From April 4, 2013, to September 22, 2015, cord blood samples, followed by venous blood samples, were obtained at birth and at 1, 7, 14, and 28 days after birth and then at postmenstrual age (PMA) 32, 36, and 40 weeks at the neonatal intensive care unit at Sahlgrenska University Hospital in Goteborg, Sweden. MAIN OUTCOMES AND MEASURES Serum phospholipid fatty acids were transmethylated and measured by gas chromatography-mass spectrometry. Mann-Whitney test, logistic regression Spearman rank correlation, and receiver operating characteristic curve analysis were used to compare differences between infants with no ROP and infants who developed ROP. RESULTS Serum levels from 78 infants (43 male [55%]; mean [SD] GA, 25.5 [1.4] weeks) with a known ROP outcome were evaluated. Lower area under the curve (AUC) of arachidonic acid (AA) (20: 4 omega-6) was seen in infants with a later diagnosis of ROP compared with infants with no ROP in the first month of life (mean, 34.05 [95% CI, 32.10-36.00] vs 37.15 [95% CI, 34.85-39.46]; P < .05). In addition, lower levels of AA at 32 weeks' PMA were seen in infants with later severe ROP compared with in those without ROP (mean, 7.06 [95% CI, 6.60-7.52] vs 8.74 [95% CI, 7.80-9.67]; P < .001). In logistic modeling, low postnatal serum levels of AA and GA at birth identified with a sensitivity greater than 90% of infants who developed ROP. CONCLUSIONS AND RELEVANCE Low postnatal levels of the omega-6 LC-PUFAs (AA) are strongly associated with ROP development. Evaluating postnatal AA fraction after birth in addition to GA may be useful for ROP prediction.
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| 10. |
- Najm, Svetlana, et al.
(author)
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Effects of a lipid emulsion containing fish oil on polyunsaturated fatty acid profiles, growth and morbidities in extremely premature infants: A randomized controlled trial
- 2017
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In: Clinical Nutrition ESPEN. - : Elsevier BV. - 2405-4577. ; 20, s. 17-23
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Journal article (peer-reviewed)abstract
- © 2017 The Authors Background & aims The purpose of the study was to compare the effects of the parenteral emulsion SMOFlipid ® , with 15% fish oil, with Clinoleic ® on retinopathy of prematurity (ROP) and other morbidities and growth, and to compare their impact on longitudinal serum levels of fatty acids. Retinopathy of prematurity, other morbidity and growth were correlated with each parenteral lipid supplement. Methods Ninety infants born at gestational age < 28 weeks were randomized to treatment with SMOFlipid ® or Clinoleic ® . Two thirds (66%) of the infants received parenteral nutrition for up to 14 days birth (median 8, range 2–14 days), and additional 25% of the infants received for up to 28 days after birth (median 21, range 15–28 days). Cord blood samples and then venous blood samples were obtained at ages 1, 7, 14, and 28 days and at postmenstrual age (PMA) 32, 36, and 40 weeks. Breastmilk was collected at postnatal day 7, and at PMA 32 and 40 weeks. Serum phospholipid and breastmilk total fatty acids were analyzed by gas chromatography–mass spectrometry. Treatment groups were compared with regard to ROP, bronchopulmonary dysplasia, necrotizing enterocolitis, patent ductus arteriosus sepsis and growth between birth and 36 weeks. Results Infants on SMOFlipid ® had higher fractions of omega-3 LCPUFA eicosapentaenoic acid (EPA) and slightly higher omega-3 LCPUFA docosahexaenoic acid (DHA) fraction and a decreased arachidonic acid (AA) to DHA ratio from one week after birth up to 32 postmenstrual weeks compared to infants on Clinoleic ® . Treatment groups did not differ in morbidities or growth. Conclusion Supplementation with SMOFlipid ® containing 15% fish oil during parenteral nutrition increased EPA substantially, DHA marginally, reduced AA and decreased AA to DHA ratio. It did not reduce morbidity or affect growth. Since extremely preterm infants accumulate a large deficit of DHA and AA, studies on more prolonged or different levels of DHA and AA supplementation are warranted.
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