When do Default Nudges Work?

Nudging is a burgeoning topic in science and in policy, but evidence on the effectiveness of nudges among differentially-incentivized groups is lacking. This paper exploits regional variations in the roll-out of the Covid-19 vaccine in Sweden to examine the effect of a nudge on groups whose intrinsic incentives are different: 16-17-year-olds, for whom Covid-19 is not dangerous, and 50-59-year-olds, who face a substantial risk of death or severe disease. The response is strong in the younger but absent in the older age group, consistent with the theory that nudges work best for choices that are not meaningful to the individual.Comment: 20 page

Structural magnetic resonance imaging of bipolar disorder

Bipolar disorders are illnesses with recurring episodes of elevated or depressed mood. Although most affected individuals have periods when they are free of symptoms, they carry a life-long risk of relapse. The cause of the illness has not yet been established. During the last three decades, a growing number of brain imaging studies have shown differences in brain morphology between persons with a bipolar disorder and healthy controls, though the affected brain regions have varied greatly across studies. Too small sample sizes are likely one explanation of this variability. The aims of this thesis were to investigate i) differences in brain morphology between bipolar patients and healthy controls, ii) differences between subgroups of bipolar disorder, and iii) changes in brain morphology associated with illness progression. To these ends, we collected a large sample of bipolar disorder patients and examined their brains using magnetic resonance imaging. We then made analyses on group level. In Study 1, we analyzed differences in gray matter volume between persons with bipolar disorder and healthy controls. We found lower volume in the bilateral insula and medial prefrontal cortex in the bipolar group. We also found that these two regions covary in size. In Study 2, we examined if cortical volume, thickness, and surface area differ between patients with bipolar disorder I and II. We found that bipolar I subjects had thinner rostral temporal cortex than bipolar II subjects. Many patients with bipolar disorder experience psychotic symptoms during an illness episode. In Study 3, we investigated if gray matter volume differs between patients with a history of psychosis and those without. We found lower volume in the fusiform gyrus, dorsolateral prefrontal cortex, and inferior frontal cortex in the group of patients with previous psychosis. In Study 4, we analyzed if gray matter volume was associated with the lifetime number of manic or depressive episodes, or the duration of the illness in a group of patients with bipolar I disorder without comorbidity. We found a linear negative correlation between the volume of the dorsolateral prefrontal cortex and the lifetime number of manic episodes. This cross sectional analysis could, however, not establish if the volume reduction predates the manic episodes or is an effect of manic episodes. Therefore, we re-scanned the patients after six years. In study 5, we then compared those patients who had had at least one manic episode between baseline and follow-up with those who did not. We found that the volume in the dorsolateral and inferior frontal cortex decreased in the group who had had a manic episode. In summary, the studies suggest that bipolar disorder is associated with reduced gray matter volume in brain areas responsible for emotional regulation. We also found that the brain morphology differs between subgroups of bipolar disorder. Finally, our results suggest that manic episodes cause gray matter volume reduction in regions coupled to cognitive functions that tend to be impaired in bipolar disorder

Electroconvulsive Therapy in Depression: Improvement in Quality of Life Depending on Age and Sex

Objectives It is uncertain if there are variations in the improvement of quality in life between sexes and age groups after electroconvulsive therapy (ECT). The aim of this study was to investigate how health-related quality of life changed after treatment and to examine differences in the results between sex and age groups. Methods This register-based study used data from the Swedish national quality register for ECT. The study population was patients diagnosed with depression who had received ECT. Health-related quality of life was quantified using the 3-level version the EuroQol 5-dimensional questionnaire (EQ-5D 3 L). Analysis of variance was used to compare change in EQ-5D score from pretreatment to posttreatment between sex and age groups. Results There was a statistically significant improvement in EQ-5D index score and EQ visual analog scale (VAS) score in all patient groups after ECT. The mean improvement in EQ-5D index score and EQ-VAS score ranged from 0.31 to 0.46 and 28.29 to 39.79, respectively. Elderly patients had greater improvement in EQ-5D index score and EQ-VAS score than younger patients. There was no significant difference in improvement between the sexes. The mean improvement in EQ-5D index score was 0.40 for male patients and 0.41 for female patients. Conclusions Electroconvulsive therapy had a considerable effect on health-related quality of life in patients with depression of both sexes and all age groups. The improvement was greatest in elderly patients, who more often had psychotic features. More studies are needed to investigate the long-term effects of ECT and to further explain the varying treatment results between elderly and younger patients.publishedVersio

Validity of diagnoses, treatment dates, and rating scales in the Swedish national quality register for electroconvulsive therapy

Background The Swedish national quality register for electroconvulsive therapy (Q-ECT) contains data on patients receiving treatment with electroconvulsive therapy (ECT) in Sweden. Aim This study determined the validity of diagnoses, treatment dates, and rating scales in the Q-ECT by investigating the degree of accordance between data from the Q-ECT and patient records. Materials and methods From January 2016 to December 2017, 200 treatment series were randomly selected from the Q-ECT. The corresponding patient records were requested from the treating hospitals. Data on the indicative diagnosis, dates for the first and the last ECT session, and rating scales were compared between the Q-ECT and patient records using (i) a strict and (ii) a liberal method of assessment. Using the liberal method, each variable was assessed as accordant if it belonged to the same diagnosis group, or if the dates differed by less than 1 week, or ratings differed by only 1 point on the Clinical Global Impression Scale (CGI- S), or no more than 3 points on the Montgomery Åsberg Depression Rating Scale between the Q-ECT and the patient record. Results A total of 179 patient records were received. The strict method of assessment showed an accordance of 89% or higher for all studied variables. The liberal method showed an accordance of 95% or higher. Conclusions We conclude that data on the studied variables in the Q-ECT have high validity. However, limited use of some rating scales makes the results uncertain. Measures can be taken to further improve the data quality.publishedVersio

System Identification and Tuning of Wireless Power Transfer Systems with Multiple Magnetically Coupled Resonators

We present a procedure for system identification and tuning of a wireless power transfer (WPT) system with four magnetically coupled resonators, where each resonator consists of a coil and a capacitor bank. The system-identification procedure involves three main steps: 1) individual measurement of the capacitor banks in the system; 2) measurement of the frequency-dependent two-port impedance matrix of the magnetically coupled resonators; and 3) determining the inductance of all coils and their corresponding coupling coefficients using a Bayesian approach. The Bayesian approach involves solving an optimization problem where we minimize the mismatch between the measured and simulated impedance matrix together with a penalization term that incorporates information from a direct measurement procedure of the inductance and losses of the coils. This identification procedure yields an accurate system model which we use to tune the four capacitance values to recover high system-performance and account for, e.g., manufacturing tolerances and coil displacement. For a prototype WPT system, we achieve 3.3 kW power transfer with 91 % system efficiency over an air-gap distance of approximately 20 cm

A novel atlas of gene expression in human skeletal muscle reveals molecular changes associated with aging

Background: Although high-throughput studies of gene expression have generated large amounts of data, most of which is freely available in public archives, the use of this valuable resource is limited by computational complications and non-homogenous annotation. To address these issues, we have performed a complete re-annotation of public microarray data from human skeletal muscle biopsies and constructed a muscle expression compendium consisting of nearly 3000 samples. The created muscle compendium is a publicly available resource including all curated annotation. Using this data set, we aimed to elucidate the molecular mechanism of muscle aging and to describe how physical exercise may alleviate negative physiological effects. Results: We find 957 genes to be significantly associated with aging (p <0.05, FDR = 5 %, n = 361). Aging was associated with perturbation of many central metabolic pathways like mitochondrial function including reduced expression of genes in the ATP synthase, NADH dehydrogenase, cytochrome C reductase and oxidase complexes, as well as in glucose and pyruvate processing. Among the genes with the strongest association with aging were H3 histone, family 3B (H3F3B, p = 3.4 x 10(-13)), AHNAK nucleoprotein, desmoyokin (AHNAK, p = 6.9 x 10(-12)), and histone deacetylase 4 (HDAC4, p = 4.0 x 10(-9)). We also discover genes previously not linked to muscle aging and metabolism, such as fasciculation and elongation protein zeta 2 (FEZ2, p = 2.8 x 10(-8)). Out of the 957 genes associated with aging, 21 (p <0.001, false discovery rate = 5 %, n = 116) were also associated with maximal oxygen consumption (VO2MAX). Strikingly, 20 out of those 21 genes are regulated in opposite direction when comparing increasing age with increasing VO2MAX. Conclusions: These results support that mitochondrial dysfunction is a major age-related factor and also highlight the beneficial effects of maintaining a high physical capacity for prevention of age-related sarcopenia.Peer reviewe

N-1-methylnicotinamide is a signalling molecule produced in skeletal muscle coordinating energy metabolism

Obesity is a major health problem, and although caloric restriction and exercise are successful strategies to lose adipose tissue in obese individuals, a simultaneous decrease in skeletal muscle mass, negatively effects metabolism and muscle function. To deeper understand molecular events occurring in muscle during weight-loss, we measured the expressional change in human skeletal muscle following a combination of severe caloric restriction and exercise over 4 days in 15 Swedish men. Key metabolic genes were regulated after the intervention, indicating a shift from carbohydrate to fat metabolism. Nicotinamide N-methyltransferase (NNMT) was the most consistently upregulated gene following the energy-deficit exercise. Circulating levels of N-1-methylnicotinamide (MNA), the product of NNMT activity, were doubled after the intervention. The fasting-fed state was an important determinant of plasma MNA levels, peaking at similar to 18 h of fasting and being lowest similar to 3 h after a meal. In culture, MNA was secreted by isolated human myotubes and stimulated lipolysis directly, with no effect on glucagon or insulin secretion. We propose that MNA is a novel myokine that enhances the utilization of energy stores in response to low muscle energy availability. Future research should focus on applying MNA as a biomarker to identify individuals with metabolic disturbances at an early stage.Peer reviewe

The Soluble Form of the Axl Receptor Tyrosine Kinase

The present investigation focus on the receptor Axl, which is a member of the receptor tyrosine kinase family. Axl is activated by the ligand Gas6 inducing cell growth and proliferation, but also regulate inflammation and vascular homeostasis. The Axl receptor can be cleaved outside the membrane, releasing the extracellular, soluble domain, which alone can bind Gas6, removing it from cellbound receptors. The first study focus on soluble Axl (sAxl), which is found to be secreted from several human cell lines and is present in human serum and plasma. An ELISA is developed against Axl to determine the concentration of sAxl in human circulation. Through immunoprecipitation and gel filtration, Gas6 is found to be in complex with sAxl, with sAxl present in excess of Gas6. In the second study, a number of patients with abdominal aortic aneurysms are investigated with Gas6 and sAxl ELISAs to widen our understanding of the Gas6-Axl system. In the patients, Gas6 is increased and sAxl is decreased in the patient group. Aneurysm size correlated to Gas6 concentration and inversly to sAxl concentration. The Gas6/sAxl ratio correlated even better to Aneurysm size, and 40% of all patients with large Aneurysms had higher Gas6/sAxl ratio than any in the control group. The third study investigated patients with critical limb ischemia. The patients had high Gas6 and sAxl, and both proteins correlated with several inflammatory markers. Patients with high Gas6 and sAxl had poorer prognosis with higher mortality, independent of age and gender. The fourth study assesed patients with Sepsis and related inflammatory conditions. In septic patients, Gas6 was twice the concentration observed in the controls, and sAxl was also increased. Gas6 was especially increased in patients with organ failure, patients demanding intensive care and renal support. The fifth study focused on patients with systemic lupus erythematosus, and in this material Gas6 and sAxl correlated with the disease index in those patients. Gas6 and sAxl was markedly increased in patients with glomerulonephritis and presence of anti-DNA antibodies. Altogether, the results from this thesis include that Gas6 is bound to sAxl in circulation and that Gas6 and sAxl are increased in inflammatory conditions

Traffic Sign Classification Using Computationally Efficient Convolutional Neural Networks

Traffic sign recognition is an important problem for autonomous cars and driver assistance systems. With recent developments in the field of machine learning, high performance can be achieved, but typically at a large computational cost. This thesis aims to investigate the relation between classification accuracy and computational complexity for the visual recognition problem of classifying traffic signs. In particular, the benefits of partitioning the classification problem into smaller sub-problems using prior knowledge in the form of shape or current region are investigated. In the experiments, the convolutional neural network (CNN) architecture MobileNetV2 is used, as it is specifically designed to be computationally efficient. To incorporate prior knowledge, separate CNNs are used for the different subsets generated when partitioning the dataset based on region or shape. The separate CNNs are trained from scratch or initialized by pre-training on the full dataset. The results support the intuitive idea that performance initially increases with network size and indicate a network size where the improvement stops. Including shape information using the two investigated methods does not result in a significant improvement. Including region information using pretrained separate classifiers results in a small improvement for small complexities, for one of the regions in the experiments. In the end, none of the investigated methods of including prior knowledge are considered to yield an improvement large enough to justify the added implementational complexity. However, some other methods are suggested, which would be interesting to study in future work