448 research outputs found

    Solar activity and Svalbard temperatures

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    The long temperature series at Svalbard (Longyearbyen) show large variations, and a positive trend since its start in 1912. During this period solar activity has increased, as indicated by shorter solar cycles. The temperature at Svalbard is negatively correlated with the length of the solar cycle. The strongest negative correlation is found with lags 10-12 years. The relations between the length of a solar cycle and the mean temperature in the following cycle, is used to model Svalbard annual mean temperature, and seasonal temperature variations. Residuals from the annual and winter models show no autocorrelations on the 5 per cent level, which indicates that no additional parameters are needed to explain the temperature variations with 95 per cent significance. These models show that 60 per cent of the annual and winter temperature variations are explained by solar activity. For the spring, summer and fall temperatures autocorrelations in the residuals exists, and additional variables may contribute to the variations. These models can be applied as forecasting models. We predict an annual mean temperature decrease for Svalbard of 3.5\pm2 oC from solar cycle 23 to solar cycle 24 (2009-20) and a decrease in the winter temperature of \approx6 oC.Comment: 14 pages, including 5 figure

    The Effects of Perinatal Fluoxetine Exposure on Social and Non-Social Investigation Behaviors in a Novel Environment

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    Selective serotonin reuptake inhibitors (SSRIs) are increasingly prescribed as medication for various affective disorders during pregnancy. SSRIs cross the placenta and affect serotonergic neurotransmission in the fetus, but the neurobehavioral consequences for the offspring remain largely unclear. Recent research has linked perinatal SSRI exposure to alterations in both social and non-social aspects of behavior. However, this research has mainly focused on behavior within simplified environments. The current study investigates the effects of perinatal exposure to SSRIs on social and non-social investigation behaviors when the individual is introduced to a novel seminatural environment with unfamiliar conspecifics. During the perinatal period (gestational day 1 until postnatal day 21), rat dams received daily either SSRI treatment (fluoxetine 10 mg/kg) or vehicle. Four cohorts of offspring, each consisting of four males and four females, were observed in adulthood during the first hour within a seminatural environment. The results showed that perinatal fluoxetine exposure altered aspects of non-social, but not social, investigation behaviors. Both fluoxetine exposed male and female rats spent more time on walking/running than controls, while fluoxetine exposed females also walked/ran more often than control animals. Furthermore, compared to control, fluoxetine exposed female rats spent less time exploring objects and specific elements in the physical environment. We suggest that perinatal exposure to SSRI lead to a quicker, less detailed investigation strategy in novel environments, and that the alteration is most pronounced in females. Whether this effect is disadvantageous or not is yet to be revealed

    Robustness Analysis of a Class of Decentralized Control Systems

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    How dynamic capabilities have helped firms seize digital transformation during the COVID-19 pandemic

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    COVID-19 and its impact on digital transformation is a subject of great interest among many industries. This thesis aim to investigate how firms have utilized dynamic capabilities to seize digital transformation during COVID-19. Thus, this study raises two main questions, (1) how and which dynamic capabilities has been utilized, (2) and how digital transformation is seized through these capabilities. There is also discussions and analysis of the impact and ramifications caused by COVID-19. We have utilized an explorative qualitative research method to investigate these questions further. The research method is done through five semi-structured interviews with five saving banks in Norway. In order to categorize and address the questions used in our interviews we have utilized a framework of dynamic capabilities in which we have sorted the different information in three different categories. Findings indicate that the banking firms themselves somewhat have negated most of the negative effects of COVID-19. Their already existing internal dynamic capabilities and digital work approach has helped them in this regard. However, their environment consisting of customers and other third-party actors has been affected in a much larger scale. In order to protect and help their customers the bank has given them more digital accessibility and freedom. During COVID-19 most interactions with third-party actors has been conducted on digital platforms. The findings suggests that this has made interactions and meetings much more efficient for all participants. There are however concerns of the long-term effects of the digital interactions. This is connected to relational and cultural values that could be negatively affected in the long-term. COVID-19 has had a reinforcing and accelerating effect on decision making, strategy planning and implementation processes. Throughout our methodical approach we have found that several internal and external factors has affected how the banks has utilized dynamic capabilities to seize digital transformation

    Separation of Aluminum from More Noble Elements in an Electrolysis Cell with Side-by-Side Geometry

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    Currently, recycled metal is diluted with primary metal to keep the concentration of alloying elements within specification. This will be more difficult in the future, when a larger proportion of the metal is made from scrap. Particularly, there is a need for a process that can remove elements more noble than aluminum from the scrap metal. While electrolytic refining in a three-layer cell (the Hoopes process) is a possibility; the present paper presents a simpler and more flexible electrolysis cell where the anode metal (alloy) and the cathode metal (purified metal) are placed side-by-side. The principle was demonstrated in a laboratory cell. The current efficiency was above 80 pct and the specific energy consumption was about 7 kWh/kg Al. The refining effect was very good, e.g., the copper content in the 7xxx alloy used was reduced from 2.1 wt pct to less than 20 ppm. An industrial version of the cell used in the present work is suggested. The principles and design are generic and can be used for other purposes than recycling aluminum.publishedVersio

    How well do neurosurgeons predict survival in patients with high-grade glioma?

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    Due to the lack of reliable prognostic tools, prognostication and surgical decisions largely rely on the neurosurgeons’ clinical prediction skills. The aim of this study was to assess the accuracy of neurosurgeons’ prediction of survival in patients with high-grade glioma and explore factors possibly associated with accurate predictions. In a prospective single-center study, 199 patients who underwent surgery for high-grade glioma were included. After surgery, the operating surgeon predicted the patient’s survival using an ordinal prediction scale. A survival curve was used to visualize actual survival in groups based on this scale, and the accuracy of clinical prediction was assessed by comparing predicted and actual survival. To investigate factors possibly associated with accurate estimation, a binary logistic regression analysis was performed. The surgeons were able to diferentiate between patients with diferent lengths of survival, and median survival fell within the predicted range in all groups with predicted survival24 months, median survival was shorter than predicted. The overall accuracy of surgeons’ survival estimates was 41%, and over- and underestimations were done in 34% and 26%, respectively. Consultants were 3.4 times more likely to accurately predict survival compared to residents (p=0.006). Our fndings demonstrate that although especially experienced neurosurgeons have rather good predictive abilities when estimating survival in patients with high-grade glioma on the group level, they often miss on the individual level. Future prognostic tools should aim to beat the presented clinical prediction skills.publishedVersio

    Meningioma segmentation in T1-weighted MRI leveraging global context and attention mechanisms

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    Meningiomas are the most common type of primary brain tumor, accounting for approximately 30% of all brain tumors. A substantial number of these tumors are never surgically removed but rather monitored over time. Automatic and precise meningioma segmentation is therefore beneficial to enable reliable growth estimation and patient-specific treatment planning. In this study, we propose the inclusion of attention mechanisms over a U-Net architecture: (i) Attention-gated U-Net (AGUNet) and (ii) Dual Attention U-Net (DAUNet), using a 3D MRI volume as input. Attention has the potential to leverage the global context and identify features' relationships across the entire volume. To limit spatial resolution degradation and loss of detail inherent to encoder-decoder architectures, we studied the impact of multi-scale input and deep supervision components. The proposed architectures are trainable end-to-end and each concept can be seamlessly disabled for ablation studies. The validation studies were performed using a 5-fold cross validation over 600 T1-weighted MRI volumes from St. Olavs University Hospital, Trondheim, Norway. For the best performing architecture, an average Dice score of 81.6% was reached for an F1-score of 95.6%. With an almost perfect precision of 98%, meningiomas smaller than 3ml were occasionally missed hence reaching an overall recall of 93%. Leveraging global context from a 3D MRI volume provided the best performances, even if the native volume resolution could not be processed directly. Overall, near-perfect detection was achieved for meningiomas larger than 3ml which is relevant for clinical use. In the future, the use of multi-scale designs and refinement networks should be further investigated to improve the performance. A larger number of cases with meningiomas below 3ml might also be needed to improve the performance for the smallest tumors.Comment: 16 pages, 5 figures, 3 tables. Submitted to Artificial Intelligence in Medicin

    Bruk av plantevernmidler i jordbruket i 2001

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    Målsetninger om redusert helse- og miljørisiko ved bruk av plantevernmidler er nedfelt i Handlingsplan for redusert risiko ved bruk av plantevernmidler 1998-2002 (Landbruksdepartementet) og i Landbruksdepartementets miljøhandlingsplan 2001-2004. Statistisk sentralbyrå har gjennomført en postal utvalgsundersøkelse for å kartlegge bruken av plantevernmidler i jordbruket i 2001. Resultatene fra undersøkelsen vil være et hjelpemiddel for nasjonale myndigheter i arbeidet med å overvåke bruken av plantevernmidler og å nå fastsatte mål om redusert helse- og miljørisiko ved bruk av slike midler. Undersøkelsen gjaldt vekstene potet, kepaløk, hodekål, gulrot, jordbær, eple, eng og beite, bygg, havre, vårhvete, høsthvete og oljevekster. Vekstene omfattet ca. 96 prosent av det totale jordbruksarealet i drift i 2001
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