Scattering theory for the Laplacian on manifolds with bounded curvature

In this paper we study the behaviour of the continuous spectrum of the Laplacian on a complete Riemannian manifold of bounded curvature under perturbations of the metric. The perturbations that we consider are such that its covariant derivatives up to some order decay with some rate in the geodesic distance from a fixed point. Especially we impose no conditions on the injectivity radius. One of the main results are conditions on the rate of decay, depending on geometric properties of the underlying manifold, that guarantee the existence and completeness of the wave operators.Comment: 45 page

The Making of an Arctic Naturalist

One of the greatest impressions of my life was my first visit to Greenland. I was a mere boy at that time, only sixteen years old .... This visit to Greenland changed my life. I lost my heart to the Arctic and realized that I must return to learn more of the secrets behind the Polar beauty. This was not my birth as a naturalist, to be sure, since from early boyhood I had wanted to study nature and its creatures, but during this Greenland trip I received a special challenge: my endeavours were now directed towards a distinct though faraway goal. ... When in 1925 at the age of sixteen I joined Schiøler's Greenland expedition I had been a member of the Danish Ornithological Society and the Danish Natural History Society for two years, admittedly an extraordinarily young member. ... I was interested in most animal groups, although favouring birds and various marine invertebrates. During that time I made the acquaintance of Dr. C. G. Johs. Petersen, director of the "Biological Station", in those days the Danish institute for marine biological research. ... I spent many evenings in Dr. Petersen's home, learning and discussing marine zoology. I was seriously inclined to choose that field, rather than ornithology, as my future specialty, until I met Ejler Lehn Schiøler, and one year later received the offer to accompany him to Greenland. Schiøler was a remarkable man. He was a banker who became very wealthy but in his spare time he was an ardent student of ornithology and succeeded in gathering a collection of more than 25,000 skins of western palearctic birds, besides skeletons and eggs. He built a large museum for his collections with an ornithological library. ... Naturally, I admired this great scientist, and in his study, when he showed me his birds and told me about the problems they posed, I gradually decided to be an ornithologist. When we left for Greenland in 1925, altogether five men, in order to collect and study the birds of the west coast, it was still the old regime. The native population lived literally under stone-age conditions, mildly ruled by the patriarchal Danish government. The Greenlanders had not changed their ancient Eskimo-like habits, living in turf-houses, wearing their seal-skin kamiks and anoraqs, and sailing in kayaks and umiaks. While writing this I am sitting in a hotel in one of the modern Greenland cities, with factories, canneries, noisy motor traffic on the broad streets and in the busy harbour, certainly a far cry from the conditions during my first visit almost 50 years ago. The primitive life of the Eskimos was, of course, something quite extraordinary for a school-boy who had just left his books. I tried to learn as much as possible about these people and their country in the short time, less than four months, in which we stayed in Greenland, and succeeded to a degree. The main thing, however, was the bird life. Series of practically all Greenland species were secured. ... I think it was the solemnity which fascinated me so much, a solemnity effected by the extreme quietness and the purity and severity of the country. ... I felt myself in a forgotten world, remote and lonely, resting in quietness, untouched by man, unspoiled. I could move around hour after hour; nothing disturbed the impression of beauty, and the changing horizons seemed endless. Here I was nearer nature's heart than anywhere else, and here I sensed a strange harmony. I admit that not all people would feel that way. ... the Arctic is so extremely simple and clear! Everything unnecessary has been removed; here there are no forests, no houses, no people; only the very backbone of nature is left. From a biological viewpoint it is significant that the number of animal and plant species is so reduced that their ecology, their mutual relationship, their adaptations to the environment are much easier to study in the polar than in the tropical regions. ... All this makes the Arctic in some respects the ideal working ground for a biologist. ... This rapport with the arctic regions has brought continuing richness and rejuvenation to my life. I have been true to my first love, and I have made several later visits to the far north; it still provides a challenge and an inspiration. By many regarded as a godforsaken waste, the polar regions are to me a place where the divine manifestation is more apparent than in other parts of the world

Ml-based porosity modeling tested on synthetic and subsurface data

This thesis investigates if synthetic porosity models are useful as a basis for comparison between machine learning (ML) approaches to porosity prediction. In addition to the ML methods, the sequential gaussian simulation (SGS) geostatistical method is used as a bench- mark. The synthetic models are porosity and impedance cubes constructed from the F3 dataset (offshore Netherlands) well-logs, to mimic specific geological geometries including a sedimentary wedge and a normal fault. Based on the performance of the different methods on the synthetic models, a porosity prediction is performed on the actual F3 dataset as well. The prediction methods discussed are SGS, and ML methods such as KNN-regression, lasso-regression, random forest-regression, and shallow neural network. The geostatistical and geophysical methods are run using Petrel, and the ML methods using Python. ML methods are better at minimizing the error while missing much of the detail of the SGS method. However, for the F3 dataset, random forest appears to capture more details than the other methods. The synthetic models provided a better basis for comparison of the different methods, however the workflow requires improvement

Review of Measures to Enhance Cost-Efficiency in CCS Wells

Carbon capture and storage is considered an essential method to mitigate climate change and global warming. In order to accelerate the deployment of CCS and make it more profitable, the costs associated with it must be reduced. The European Union has put a cap on the CO2 market through the EU ETS allowance price, which means that the levelized costs per tonne of CO2 captured and stored can’t exceed this amount. The potential cost reduction by substituting expensive 25 Cr tubing with GRE lined carbon steel has been examined and was found to give a cost reduction of 0.4-0.6 % per tonne of CO2 stored. Although this may seem like an insignificant reduction, the global scale of things will still make this significant. Furthermore, simplification and tailor-made equipment will also contribute to necessary revenue for this emerging industry

The Greenland Bird-Banding System

Describes program of Ministeriet for Gronland and Universitetets Zoologiske Museum, Kobenhavn, initiated in 1946, with note of earlier banding by Dr. Bertelsen (reported in AB. No. 1475). Settlement and outpost managers (approx. 80) organize local banding on standard instructions in Eskimo and Danish (illus.) and forward records at end of season to the Museum. A total of 30,215 birds were ringed during 1946-1954, and 2,474 recovered, mostly shot and mostly (2,291) in Greenland. Data are tabulated for species (39), also recovery percentages for the more common forms. Migration routes disclosed are briefly discussed. An arctic tern, banded in Disko and recovered in Natal 18,000 km distant in less than three months, is signalized as the longest flight recorded by banding. Addendum offers further recovery data (abroad) and first results from East Greenland banding initiated in 1955

The Role of Top-Down and Bottom-Up Processing in Auditory False Perceptions: A Signal Detection Analysis

There is a tendency in the literature to find people with a high hallucination proneness to have significantly lower response bias but no significant difference for sensitivity compared to people with low hallucination proneness, when performing a signal detection theory (SDT) task. However, results have varied across studies, and the relation is poorly understood. We wanted to increase our understanding by investigating the effect of different levels of semantic expectation and different types of noise on hallucinatory reports among those with high and low hallucination proneness. A large student sample was screened using a revised version of the Launay-Slade Hallucination Scale (LSHS). Students with high and low hallucination proneness were asked to take part in the second phase of the study. In this phase they performed an auditory SDT task where both the semantic expectation of sentences and the noise were manipulated. Participants also completed measures of perception anomalies (Cardiff Anomalous Perceptions Scale), fantasy proneness (Creative Experiences Questionnaire), suggestibility (Multidimensional Iowa Suggestibility Scale), aberrant salience (Aberrant Salience Inventory), and encoding style (Encoding Style Questionnaire). Results showed that participants in the high hallucination proneness group had a lower response bias compared to participants in the low hallucination proneness group when there was a combination of a high level of semantic expectation and Bergen noise. This suggests that both bottom-up and topdown factors are needed to elicit auditory hallucinatory experiences. Furthermore, hallucination proneness, aberrant salience and encoding style all had significant, negative correlations with response bias, indicating that they could all be implicated in the occurrence of auditory hallucinatory experiences.Det er en tendens i litteraturen til å finne at folk med høy hallusinasjonstendens har signifikant lavere respons bias, men ingen signifikant forskjell for sensitivitet sammenlignet med folk med lav hallusinasjonstendens, når de utfører en signaldeteksjonsoppgave. Til tross for den generelle tendensen har resultatene variert på tvers av studier, og forholdet er lite forstått. Vi ønsker å øke vår forståelse ved å undersøke effekten av ulike nivåer av semantisk forventning og ulike typer støy, på hallusinasjonsrapporter blant personer med høy og lav hallusinasjonstendens. Et stort utvalg studenter ble forhåndstestet ved å bruke en revidert versjon av Launay-Slade Hallucination Scale (LSHS). Studentene med høy og lav hallusinasjonstendens ble spurt om å ta del i den andre fasen av studien. I denne fasen utførte de en auditiv signaldeteksjonsoppgave hvor både den semantiske forventningen til setningene og støyen var manipulert. Deltakerne utførte også målinger av persepsjonsavvik (Cardiff Anomalous Perceptions Scale), fantasitendens (Creative Experiences Questionnaire), suggestibilitet (Multidimensional Iowa Suggestibility Scale), avvikende betydning (Aberrant Salience Inventory), og innkodingsstil (Encoding Style Questionnaire). Resultatene viste at deltakere i høy hallusinasjonstendensgruppen hadde en lavere respons bias sammenlignet med lav hallusinasjonstendensgruppen når det var en kombinasjon av høyt nivå av semantisk forventning og Bergenstøy. Dette peker på at både bottom-up og top-down faktorer er nødvendige for å fremkalle auditive hallusinasjons-opplevelser. Videre hadde hallusinasjonstendens, avvikende betydning og innkodingsstil alle signifikante negative korrelasjoner med respons bias, noe som indikerer at de alle ser ut til å være impliserte i forekomsten av auditive hallusinasjons-opplevelser.Masteroppgave i psykologiMAPSYK36

Patients’ preferences for management of deep occlusal, initial occlusal and root carious lesions

Introduction: Evidence-based dentistry is a threefold method of working as a dentist. The threefold method is clinical experience, evidence-based research and patients’ preferences. The purpose of this study was to investigate patient’s preferences for management of different carious lesions; initial occlusal carious lesions, deep occlusal carious lesions, and root carious lesions, and if there was any relationship between patient’s preferences and their characteristics. Methods: This cross-sectional study consisted of a questionnaire and case vignettes. The questionnaire included questions about gender, age, population in home town, dental history, modified dental anxiety score and the ten-item personality score. The case vignettes consisted of description of two management options for each of three types of carious lesions: stepwise excavation and selective excavation for deep occlusal carious lesions, fissure sealant and fluoride/hygiene regimen for initial occlusal carious lesions, and filling and fluoride/hygiene- regimen for root carious lesions. We used convenient sampling to recruit participants at Pingvinhotellet, a hotel dedicated for patients and next of kin, at the University Hospital in North of Norway in Tromsø. There were 168 persons who were asked to participate, and 147 persons responded to case vignettes and questionnaires. Out of these 7 answers were excluded, which gave us 140 answers to analyze. The response rate was 88%. The results were analyzed using univariable and a multivariable binary logistic regression analysis. Results: There were 65 men and 75 women that participated in the study. Out of them, 75 (53,6%) respondents preferred selective excavation and 65 (46,4%) preferred stepwise excavation when presented to the vignettes describing deep occlusal carious lesion. There were 86 (61,4%) respondents that preferred fissure sealant and 54 (38,6%) that preferred fluoride/hygiene regimen when presented to the vignettes describing initial occlusal carious lesion. There were 91 (65%) of the respondents that preferred filling and 49 (35%) that preferred fluoride varnish/ hygiene regimen when presented to the vignettes describing root carious lesion. For initial occlusal carious lesions, the multivariable binary logistic regression analysis showed that there was a statistically significant association between not having the same dentist or dental hygienist for three years or more versus having the same dentist for 3 years or more, and preference for fluoride varnish/hygiene regimen (OR 2.644, 95%CI 1.112- 6.287). For root carious lesions, the analysis showed that the personality trait “agreeable” test was statistical significantly associated with the preference of operative management alternative (OR 0.562, 95%CI 0.358- 0.882). In addition, there was a statistically significant association between preference of fluoride varnish/hygiene regimen and having a PhD academic degree versus primary school education (OR 10.620, 95%CI 1.062- 106.170). Conclusion: Regarding deep occlusal carious lesions, participants equality preferred both management option, while for initial occlusal and root carious lesions almost two third of the participants preferred more invasive management options, fissure sealing and filling, respectively. There was a statistically significant association between the preferred management of initial occlusal carious lesions; preferring fluoride varnish/hygiene regimen and not having the same dentist for three years or more. It was also a significant association between the preferred management of root carious lesions; preference of the filling associated with having the personality trait “agreeable”. Also, for root carious lesions there was a significant association between preferring fluoride varnish/hygiene regimen and having a PhD academic degree. The results in this study may open up for a connection and a dialogue with a patient and this may lead to let the patient feel that they are participating in the decision-making of management of different types of carious lesions, which in itself is an important part of practicing evidence-based dentistry. There is a need for more qualitative design research in order to understand which patient characteristics are important in decision making. In addition, there is a need for more research to find out if and which management associated factors are important to people to find their preferences for a particular management

Strong Privacy Protection in Electronic Voting

We give suggestions for protection against adversaries with access to the voter's equipment in voting schemes based on homomorphic encryption. Assuming an adversary has complete knowledge of the contents and computations taking place on the client machine we protect the voter's privacy in a way so that the adversary has no knowledge about the voter's choice. Furthermore, an active adversary trying to change a voter's ballot may do so, but will end up voting for a random candidate. To accomplish the goal we assume that the voter has access to a secondary communication channel through which he can receive information inaccessible to the adversary. An example of such a secondary communication channel is ordinary mail. Additionally, we assume the existence of a trusted party that will assist in the protocol. To some extent, the actions of this trusted party are verifiable