31 research outputs found
Misinformation and polarisation in a political context
No full textThis study examines the role of social media, most notably X (formerly Twitter), and its rolein relation to the spread of misinformation, heightening polarisation, and threateningdemocratic values.Focusing on social medias role leading up to the Capitol Storming, January 6, 2021, theresearch highlights how digital platforms facilitate the rapid spreading of emotionallycharged and misleading content. Misinformation, amplified by the attention economy, thriveson content that provokes strong reactions, such as urgency and anger, which promotesengagement and visibility.The findings highlight the erosion of deliberative democracy, as misinformation dominatespublic discourse, suppressing fact-based dialogue and promoting ideological content. Socialmedia’s algorithms are designed to prioritise engagement over accuracy, further exacerbatingthese dynamics by amplifying divisive and false content, and deepening polarisation. Thisproject concludes that the spread of misinformation through social media poses a significantchallenge to democratic governance, necessitating critical reforms to digital platforms and adeeper understanding of semiotics role in shaping public perception
Early option exercise: Never say never
No full textAbstractA classic result by Merton (1973) is that, except just before expiration or dividend payments, one should never exercise a call option and never convert a convertible bond. We show theoretically that this result is overturned when investors face frictions. Early option exercise can be optimal when it reduces short-sale costs, transaction costs, or funding costs. We provide consistent empirical evidence, documenting billions of dollars of early exercise for options and convertible bonds using unique data on actual exercise decisions and frictions. Our model can explain as much as 98% of early exercises by market makers and 67% by customers
Financial Frictions: Implications for Early Option Exercise and Realized Volatility
No full textA call option on a stock is a common and widely used derivative. On an average trading day in 2015, more than 800,000 such options traded on the Chicago Board Options Exchange, the largest options exchange in the United States. Each option grants its owner the right to buy 100 of a specific stock at a pre-specified price, no later than a pre-specified date. For example, an option can grant the right to buy 100 General Electric shares for USD 31 each no later than October 21, 2016. An interesting issue is determining when an option is optimally exercised. Merton (1973) shows that in a world without frictions, a call option should never be exercised early, but only at expiration or just before the underlying stock pays a dividend. Chapter one of this thesis shows that suffciently severe frictions can make early exercise optimal. Short-sale costs especially represent an important driver of early exercise. Chapter two shows that when option owners exercise early, it predicts stock returns, consistent with option owners acting on private information. Chapter three does not include options but shows that demand shifts in the shorting market for stocks predict the volatility of the affected stocks, which is consistent with increases in differences of opinions among market participants
Implications for Early Option Exercise and Realized Volatility
No full textA call option on a stock is a common and widely used derivative. On an average trading day in
2015, more than 800,000 such options traded on the Chicago Board Options Exchange, the largest
options exchange in the United States. Each option grants its owner the right to buy 100 of a
specific stock at a pre-specified price, no later than a pre-specified date. For example, an option
can grant the right to buy 100 General Electric shares for USD 31 each no later than October 21,
2016. An interesting issue is determining when an option is optimally exercised. Merton (1973)
shows that in a world without frictions, a call option should never be exercised early, but only at
expiration or just before the underlying stock pays a dividend. Chapter one of this thesis shows that
suffciently severe frictions can make early exercise optimal. Short-sale costs especially represent
an important driver of early exercise. Chapter two shows that when option owners exercise early, it
predicts stock returns, consistent with option owners acting on private information. Chapter three
does not include options but shows that demand shifts in the shorting market for stocks predict
the volatility of the affected stocks, which is consistent with increases in differences of opinions
among market participants
Instrumentering, Modellering og Regulering af AAU-BOT1
No full textThe aim of this master's thesis is to equip the humanoid robot AAU-BOT1 with sensors, model and control it such that it can obtain static gait. AAU-BOT1 has human proportions and features 17 actuated degrees of freedom. To enable AAU-BOT1 to obtain static gait, an instrumentation strategy has been proposed and implemented. Furthermore a software platform is developed to complete the instrumentation. Models of the DC-motors, kinematics, inverse kinematics and the dynamics of AAU-BOT1 have been made. By utilizing the inverse kinematic model, static gait trajectories are developed. The remaining models are utilized to create two different control strategies. The first control strategy is based on a Linear Quadratic Gaussian controller(LQG), which controls the posture of the robot based on the dynamic model. The second control strategy is based on classical PID controllers, and utilizes the build in features of the digital DC motor amplifiers. Both control strategies contains a balance controller, that is used to maintain stability during walk. It is furthermore decided to develop a virtual representation of the AAU-BOT1 for test purposes. The LQG controller strategy with the proposed trajectories was tested on the virtual AAU-BOT1 but the controller could not stabilize the robot sufficiently. The second control strategy was successful and the virtual robot is able to walk with the proposed trajectories and maintain stability at the same time. The second control strategy was only partially implemented on the physical AAU-BOT1 and showed promising results of obtaining static walk
How repeated time to event (RTTE) modelling of opioid requests after surgery may improve future post-operative pain management.
No full textTitle: How Repeated Time To Event (RTTE) modelling of opioid requests after surgery may improve future post-operative pain management Author: Rasmus Vestergaard Juul (1) Sten Rasmussen (2) Mads Kreilgaard (1) Ulrika S. H. Simonsson (3) Lona Louring Christrup (1) Trine Meldgaard Lund (1) Institution: (1) Dept. of Drug Design and Pharmacology, University of Copenhagen, Denmark (2) Orthopaedic Surgery Research Unit, Aalborg University Hospital, Denmark (3) Dept. of Pharmaceutical Biosciences, Uppsala University, Sweden Type: Poster: Drug/Disease modelling – CNSObjectives: Amount of opioid (eg. morphine) required by patients after surgery is often used as a surrogate measure for pain intensity in post-operative pain. However, the dynamic development of pain intensity over time is often ignored when investigating new analgesic treatments for post-operative pain1. This work included a Repeated Time to Event (RTTE) modelling2 approach of repeated opioid request in order to increase the understanding of pain breakthrough patterns in severe surgeries and improve patients’ pain management.Methods: 68 patients (F:45,M:23, Age:76±15) were included from a population receiving surgery after hip fracture at Orthopaedic Department, Aalborg University Hospital, Denmark during the period May-Dec 2012. Morphine administration times (estimated precision: ±5mins), formulations and doses were extracted from medical journals in the hospitalization period or until 96 hours after surgery. RTTE modelling was performed in NONMEM 7.2 with Pirana, PsN and Xpose- and ggplot2 libraries for R3,4. Weibull and Gompertz distributions were investigated as hazard models. Visual Predictive Check (VPC) of Kaplan Meier survival curves as well objective function value was used to evaluate the model fit.Results: A base RTTE model based on a Weibull distribution fitted the pooled data. However, VPCs showed that morphine request was not adequately described by the base models on all surgery types. This suggests that pain events do not occur in similar patterns in different surgeries. The developed RTTE model provide a base for investigation of surgery specific, drug concentration related, population specific and/or time-varying covariates of opioid requests and pain events.Conclusions: A framework has been developed based on RTTE modelling that may help improve future pain management by 1) Identification of surgery specific patterns in pain events and 2) Evaluation of concentration related effects of opioids.References:[1] McQuay et al. 2008. Br J Anaesth. 101(1):69-76 [2] Plan et al. 2011. J Pharmacol Exp Ther. 339(3):878-85[3] Keizer et al 2013. CPT Pharmacometrics Syst Pharmacol. 26;2:e50[4] Wickham 2009. ggplot2: elegant graphics for data analysis. Springer.<br/
Risk of major adverse cardiovascular events, severe hypoglycemia and all-cause mortality for popular anti-hyperglycemic dual and triple therapies for type 2 diabetes management – a cohort study of all Danish users
No full textRisk of Major Adverse Cardiovascular Events, Severe Hypoglycemia, and All-Cause Mortality for Widely Used Antihyperglycemic Dual and Triple Therapies for Type 2 Diabetes Management:A Cohort Study of All Danish Users
No full textOBJECTIVE: The vast number of antihyperglycemic medications and growing amount of evidence make clinical decision making difficult. The aim of this study was to investigate the safety of antihyperglycemic dual and triple therapies for type 2 diabetes management with respect to major adverse cardiovascular events, severe hypoglycemia, and all-cause mortality in a real-life clinical setting.RESEARCH DESIGN AND METHODS: Cox regression models were constructed to analyze 20 years of data from the Danish National Patient Registry with respect to effect of the antihyperglycemic therapies on the three end points.RESULTS: A total of 66,807 people with type 2 diabetes were treated with metformin (MET) plus a combination of second- and third-line therapies. People on MET plus sulfonylurea (SU) had the highest risk of all end points, except for severe hypoglycemia, for which people on MET plus basal insulin (BASAL) had a higher risk. The lowest risk of major adverse cardiovascular events was seen for people on a regimen including a glucagon-like peptide 1 (GLP-1) receptor agonist. People treated with MET, GLP-1, and BASAL had a lower risk of all three end points than people treated with MET and BASAL, especially for severe hypoglycemia. The lowest risk of all three end points was, in general, seen for people treated with MET, sodium-glucose cotransporter 2 inhibitor, and GLP-1.CONCLUSIONS: Findings from this study do not support SU as the second-line treatment choice for patients with type 2 diabetes. Moreover, the results indicate that adding a GLP-1 in people treated with MET and BASAL could be considered, especially if those people suffer from severe hypoglycemia.</p
Population pharmacokinetic modelling of morphine, gabapentin and their combination in the rat
No full textPurpose: The combination of morphine and gabapentin seems promising for the treatment of postoperative and neuropathic pain. Despite the well characterised pharmacodynamic interaction, little is known about possible pharmacokinetic interactions. The aim of this study was to evaluate whether co-administration of the two drugs leads to modifications of their pharmacokinetic profiles. Methods: The pharmacokinetics of morphine, morphine-3-glucuronide and gabapentin were characterised in rats following subcutaneous injections of morphine, gabapentin or their combination. Non-linear mixed effects modelling was applied to describe the pharmacokinetics of the compounds and possible interactions. Results: The plasma-concentration-time profiles of morphine and gabapentin were best described using a three- and a one-compartment disposition model respectively. Dose dependencies were found for morphine absorption rate and gabapentin bioavailability. Enterohepatic circulation of morphine-3-glucuronide was modelled using an oscillatory model. The combination did not lead to pharmacokinetic interactions for morphine or gabapentin but resulted in an estimated ~31% diminished morphine-3-glucuronide formation. Conclusions: The finding of a lack of pharmacokinetic interaction strengthens the notion that the combination of the two drugs leads to better efficacy in pain treatment due to interaction at the pharmacodynamic level. The interaction found between gabapentin and morphine-3-glucuronide, the latter being inactive, might not have any clinical relevance.PurposeThe combination of morphine and gabapentin seems promising for the treatment of postoperative and neuropathic pain. Despite the well characterised pharmacodynamic interaction, little is known about possible pharmacokinetic interactions. The aim of this study was to evaluate whether co-administration of the two drugs leads to modifications of their pharmacokinetic profiles.MethodsThe pharmacokinetics of morphine, morphine-3-glucuronide and gabapentin were characterised in rats following subcutaneous injections of morphine, gabapentin or their combination. Non-linear mixed effects modelling was applied to describe the pharmacokinetics of the compounds and possible interactions.ResultsThe plasma-concentration-time profiles of morphine and gabapentin were best described using a three- and a one-compartment disposition model respectively. Dose dependencies were found for morphine absorption rate and gabapentin bioavailability. Enterohepatic circulation of morphine-3-glucuronide was modelled using an oscillatory model. The combination did not lead to pharmacokinetic interactions for morphine or gabapentin but resulted in an estimated ~33% diminished morphine-3-glucuronide formation.ConclusionsThe finding of a lack of pharmacokinetic interaction strengthens the notion that the combination of the two drugs leads to better efficacy in pain treatment due to interaction at the pharmacodynamic level. The interaction found between gabapentin and morphine-3-glucuronide, the latter being inactive, might not have any clinical relevance
