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Stay on Target: Population Projections and Microsimulation Design
Get PDFEven though standard cohort component models are relatively easy to comprehend, designing simulations to match expected population estimates and projections in multiple countries and over long spans of time is surprisingly challenging. We identify microsimulation design options that replicate United Nations population estimates and projections in three countries (Norway, United States, and India) over a 150-year time span. The design adapts the United Nations cohort component model, which implies a certain ordering of demographic events, and uses either cohorts or age groups to assign risk. We design four simple microsimulations that use United Nations demographic statistics as exogenous variables. One model adjusts event ordering and assignment of risk by age, called the Split Fertility design, and one model does not. Each model operates in either one- or five-year steps. The Split Fertility design has less than one percent divergence in total births, deaths, and population in all three countries. The simpler design produces varying magnitudes of divergence, as large as 20% in India. The Split Fertility design is suitable for simulations that seek to maintain population dynamics in multiple countries, whether operating in one- or five-year steps. The Split Fertility design is ideal for comparative simulations that adapt demographic statistics from cohort component models. Development of the design highlights the flexibility of simulations and the importance of careful interpretation of exogenous statistics in simulation design.publishedVersio
A System Perspective on Implementation and Usage of the Da Vinci Technology at a Large Norwegian Regional Hospital
Get PDFThe aim of this research paper is to identify advantages and barriers to implementation and usage of robotic-assisted surgery (RAS), specifically the Da Vinci robot, at a larger regional hospital in Norway and from a multiple stakeholder perspective. The identified advantages and barriers are connected to the socio-technical system framework SEIPS, thereby establishing a broader contextual system perspective on RAS implementation and usage. Our findings both align and extend upon existing human factors and ergonomics (HFE) knowledge on RAS in the operating room. In terms of specific future directions, we believe that a pressing concern for both management and current HFE research involving RAS implementation and usage relates to exploring and accounting for the close connections between the organization itself and the external stakeholders that exert a considerable influence on the internal work system and processes and the ability to achieve cost-efficiency and safety levels. We further conclude that the SEIPS framework can be a powerful tool in drawing or eliciting the larger contextual picture of RAS implementation and usage, and we encourage further HFE research to explore its application in different contexts to improve the current knowledge base.publishedVersio
Simulating offshore hydrogen production via PEM electrolysis using real power production data from a 2.3 MW floating offshore wind turbine
Get PDFThis work presents simulation results from a system where offshore wind power is used to produce hydrogen via electrolysis. Real-world data from a 2.3 MW floating offshore wind turbine and electricity price data from Nord Pool were used as input to a novel electrolyzer model. Data from five 31-day periods were combined with six system designs, and hydrogen production, system efficiency, and production cost were estimated. A comparison of the overall system performance shows that the hydrogen production and cost can vary by up to a factor of three between the cases. This illustrates the uncertainty related to the hydrogen production and profitability of these systems. The highest hydrogen production achieved in a 31-day period was 17 242 kg using a 1.852 MW electrolyzer (i.e., utilization factor of approximately 68%), the lowest hydrogen production cost was 4.53 $/kg H2, and the system efficiency was in the range 56.1–56.9% in all cases.publishedVersio
Mikroplast og miljøgifter i vann, jord og insekter på Lisle Lyngøy (delrapport 3)
No full textRapporten er en delrapport fra arbeidspakke 3 i hovedprosjektet «Hvordan Plast og Plastrydding påvirker Økosystemet på Lisle Lyngøy».Delrapporten konsentrerer seg om mengder og kilder til marin forsøpling, mikroplast og miljøgifter på den ubebodde øyen Lisle Lyngøy der plast har akkumulert i flere tiår. Vi har observert og kartlagt marin plastforsøpling, og også tatt prøver av vann, jordsmonn, bunnsediment og insekter for innhold av plast, mikroplast og miljøgifter. Biodiversitet i insektsamfunnet i tjernet er også beskrevet. Det ble gjort en opprydding etter miljøundersøkelsene som ble utført første år av prosjektet, og endringen ett år etter rydding er beskrevet med hensyn til mengde mikroplast, miljøgifter i vann og biodiversitet i insektsamfunnet.Handelens Miljøfon
Trends in physical health complaints among adolescents from 2014 – 2019: Considering screen time, social media use, and physical activity
Get PDFThe rising rates of physical and mental health complaints among adolescents observed in many countries have coincided with an increased time spent on screen-based devices, including social media use. We sought to document recent trends in physical health complaints (PHC) and whether co-occurring trends in screen time, social media use, and physical activity may account for these trends. To achieve these aims, we used data from the nationwide Ungdata surveys conducted annually at the municipality level in Norway, comprising 419,934 adolescents aged 13–18 from six survey years (2014–2019). Six items assessed PHC, including neck and shoulder pain, headache, and abdominal pain, during the past month. To account for the nesting structure of Ungdata, and to exploit the variation within and between municipalities, we used multilevel analyses with adolescents nested in municipality-years (n = 669), nested in municipalities (n = 345). We found a small to moderate linear increase in number of PHC among boys and girls from 2014 to 2019. Screen time and social media use moderately attenuated the trend for girls, and to a lesser extent for boys. Screen time and social media use were further positively associated with PHC across the between and within-municipality levels, and social media use was more strongly associated with PHC for girls than boys across all levels of analysis. A similar pattern emerged when considering each symptom individually. The results suggest that the prevalence of PHC rose in tandem with a group-level shift towards higher screen time and social media use. Moreover, the results indicate that higher screen time and social media use may have led to changes in the youth culture with potential consequences for adolescents’ well-being.publishedVersio
Food anticipatory behaviour on European seabass in sea cages: activity-, positioning-, and density-based approaches
Get PDFFarmed fish like European seabass (Dicentrarchus labrax) anticipate meals if these are provided at one or multiple fixed times during the day. The increase in locomotor activity is typically known as food anticipatory activity (FAA) and can be observed several hours prior to feeding. Measuring FAA is often done by demand feeders or external sensors such as cameras or light curtains. However, purely locomotor-activity-based FAA may provide an incomplete view of feeding and prefeeding behaviour. Here, we show that FAA can be measured through passive acoustic telemetry utilising three different approaches and suggest that adding more means to food anticipation detection is beneficial. We compared the diving behaviour, acceleration activity, and temperature of 22 tagged individuals over the period of 12 days and observed FAA through locomotor activity, depth position, and density-based unsupervised clustering (i.e., DBSCAN). Our results demonstrate that the position- and density-based methods also provide expressions of anticipatory behaviour that can be interchangeable with locomotor-driven FAA or precede it. We, therefore, support a unified framework for food anticipation: FAA should only describe locomotor-driven FAA. Food anticipatory positioning (FAP) should be a term for position-based (P-FAP) and density-based (D-FAP) methods for food anticipation. Lastly, FAP, together with the newly defined FAA, should become part of an umbrella term that is already in use: food anticipatory behaviour (FAB). Our work provides data-driven approaches to each FAB category and compares them with each other. Furthermore, accurate FAB windows through FAA and FAP can help increase fish welfare in the aquaculture industry, and the more approaches available, the more flexible and more robust the usage of FAB for a holistic view can be achieved.Food anticipatory behaviour on European seabass in sea cages: activity-, positioning-, and density-based approachespublishedVersio
Induced Currents in the Lining and Steel Shell of Submerged Arc Furnaces
Get PDFNumerical models in 2D and 3D are used to study induced currents in the lining and steel shell of large three-phase submerged arc furnaces. The alternating currents supplied through the electrodes cause a significant amount of induced power in the furnace lining and shell. The induced currents flow in three large loops with an accumulation of current near the top of the steel shell between the electrodes. The net result is a thermal loss with heat dissipated at the surface. Furthermore, such accumulation may cause potentially damaging hot spots in the steel. If this persists over a long time, the shell may thin and deteriorate and, in worst-case scenarios, the shell may be cracked or punctured. The influence of an electrically conducting lining and the effect of subdividing the shell in insulated sections have been studied. It is shown that an electrically conducting lining will have a significant shielding effect on the steel shell. The induced currents are considerably reduced in the steel, and “pushed into” the lining. The size of current loops in the shell can be restricted by subdividing the steel into sections with insulation between each section. Such modification is detrimental. Strong opposing currents will be formed on each side of the insulating gaps, leading to higher current concentrations and increasing the risk of hot spots on the steel shell. In addition, the heat loss due to induced currents in the steel will be enhanced.Induced Currents in the Lining and Steel Shell of Submerged Arc FurnacespublishedVersio
Magnitude, Trends, and Variability of the Global Ocean Carbon Sink From 1985 to 2018
Get PDFThis contribution to the RECCAP2 (REgional Carbon Cycle Assessment and Processes) assessment analyzes the processes that determine the global ocean carbon sink, and its trends and variability over the period 1985–2018, using a combination of models and observation-based products. The mean sea-air CO2 flux from 1985 to 2018 is −1.6 ± 0.2 PgC yr−1 based on an ensemble of reconstructions of the history of sea surface pCO2 (pCO2 products). Models indicate that the dominant component of this flux is the net oceanic uptake of anthropogenic CO2, which is estimated at −2.1 ± 0.3 PgC yr−1 by an ensemble of ocean biogeochemical models, and −2.4 ± 0.1 PgC yr−1 by two ocean circulation inverse models. The ocean also degasses about 0.65 ± 0.3 PgC yr−1 of terrestrially derived CO2, but this process is not fully resolved by any of the models used here. From 2001 to 2018, the pCO2 products reconstruct a trend in the ocean carbon sink of −0.61 ± 0.12 PgC yr−1 decade−1, while biogeochemical models and inverse models diagnose an anthropogenic CO2-driven trend of −0.34 ± 0.06 and −0.41 ± 0.03 PgC yr−1 decade−1, respectively. This implies a climate-forced acceleration of the ocean carbon sink in recent decades, but there are still large uncertainties on the magnitude and cause of this trend. The interannual to decadal variability of the global carbon sink is mainly driven by climate variability, with the climate-driven variability exceeding the CO2-forced variability by 2–3 times. These results suggest that anthropogenic CO2 dominates the ocean CO2 sink, while climate-driven variability is potentially large but highly uncertain and not consistently captured across different methods.publishedVersio
The Relationship Between the Global Mean Deep-Sea and Surface Temperature During the Early Eocene
Get PDFEstimates of global mean near-surface air temperature (global SAT) for the Cenozoic era rely largely on paleo-proxy data of deep-sea temperature (DST), with the assumption that changes in global SAT covary with changes in the global mean deep-sea temperature (global DST) and global mean sea-surface temperature (global SST). We tested the validity of this assumption by analyzing the relationship between global SST, SAT, and DST using 25 different model simulations from the Deep-Time Model Intercomparison Project simulating the early Eocene Climatic Optimum (EECO) with varying CO2 levels. Similar to the modern situation, we find limited spatial variability in DST, indicating that local DST estimates can be regarded as a first order representative of global DST. In line with previously assumed relationships, linear regression analysis indicates that both global DST and SAT respond stronger to changes in atmospheric CO2 than global SST by a similar factor. Consequently, this model-based analysis validates the assumption that changes in global DST can be used to estimate changes in global SAT during the early Cenozoic. Paleo-proxy estimates of global DST, SST, and SAT during EECO show the best fit with model simulations with a 1,680 ppm atmospheric CO2 level. This matches paleo-proxies of EECO atmospheric CO2, indicating a good fit between models and proxy-data.publishedVersio
Two Distinct Phases of North Atlantic Eastern Subpolar Gyre and Warming Hole Evolution under Global Warming
Get PDFThe North Atlantic subpolar gyre (SPG) plays a crucial role in determining the regional ocean surface temperature (SST), which has profound implications on the surrounding continental and coastal climate. Here, we analyze the Max Planck Institute-Grand Ensemble global warming experiments and show that the SPG can evolve in two distinct phases under continuous global warming. In the first phase, as the global mean surface temperature approaches 2-K warming, the eastern SPG intensifies in combination with a weakening Atlantic meridional overturning circulation (AMOC), accompanied by a cooling of subpolar North Atlantic SST, known as the warming hole. The associated oceanic fingerprint matches with the observations over the last 15 years, where an intensification and cooling of the eastern SPG is related to salinity reduction at the eastern side of the SPG. However, for further warming beyond 2 K, in spite of a continuous decline in the AMOC, a northward shift of the mean zonal wind extends the subtropical gyre northward with an associated disruption of the eastern SPG intensification, resulting in the cessation of the warming hole. Therefore, a shift from the initially dominating oceanic drivers to the atmospheric driver results into a two-phase evolution of the North Atlantic Ocean SPG circulation and the associated SST under continuous global warming.Two Distinct Phases of North Atlantic Eastern Subpolar Gyre and Warming Hole Evolution under Global WarmingpublishedVersio