Title: Boolean techniques in Knowledge representation Author: Miloš Chromý Department: Department of Theoretical Computer Science and Mathematical Logic Supervisor: Doc. RNDr. Ondřej Čepek, Ph.D., Department of Theoretical Com- puter Science and Mathematical Logic Abstract: In this thesis we will investigate switch-list representations of Boolean function and we will explore the biclique satisfiable formulas. Given a truth table representation of a Boolean function f the switch-list rep- resentation of f is a list of Boolean vectors from the truth table which have a different function value than the preceding Boolean vector in the truth table. We include this type of representation in the Knowledge Compilation Map [Dar- wiche and Marquis, 2002] and argue that switch-lists may in certain situations constitute a reasonable choice for a target language in knowledge compilation. First, we compare switch-list representations with a number of standard repre- sentations (such as CNF, DNF, and OBDD) with respect to their relative suc- cinctness. As a by-product of this analysis we also give a short proof of a long standing open question from [Darwiche and Marquis, 2002], namely the incom- parability of MODS (models) and PI (prime implicates) representations. Next, using the succinctness result between...

E-commerce has seen a rapid growth the last two decades, making it easy for customers to shop wherever they are. The growth has also led to new kinds of fraudulent activities affecting the customers. To make customers feel safe while shopping online, companies like Resurs Bank are implementing different kinds of fraud filters to freeze transactions that are thought to be fraudulent. The latest type of fraud filter is based on machine learning. While this seems to be a promising technology, data and algorithms need to be tuned properly to the task at hand. This thesis project gives a proof of concept of realizing a machine learning based fraud filter for Resurs Bank. Based on a literature study, available data and explainability requirements, this work opts for a supervised learning approach based on Random Forests with a sliding window to overcome concept drift. The inherent class imbalance of the setting makes the area-under-the-receiver operating-curve a suitable metric. This approach provided promising results that a machine learning based fraud filter can add value to companies like Resurs Bank. An alternative approach on how to incorporate non-numerical features by using recurrent neural networks (RNN) was implemented and compared. The non-numerical feature was transformed by a pre-trained RNN-model to a numerical representation that reflects the features suspiciousness. This new numerical feature was then included in the Random Forest model and the result demonstrated that this approach can add valuable insight to the fraud detection field.

A common problem within positron emission tomography examinations of the brain is the motion of the patient. If the patients ́ head moves during an examination all the data acquired after the movement will not be suited for clinical use. This means that a lot of data recovered from PET is not used at all. Motion tracking during PET acquisitions of the brain is not a well explored issue within medical imaging in relation to the magnitude of the problem. Due to the radiation risks of the examination and the logistics at the hospital, a second acquisition is not preferred. Therefore a method to avoid a second acquisition would be welcome. PET data saved in list mode makes it possible to analyze the data during an examination. By calculating the center of mass of the object examined in list mode only using the raw data from PET and use it as a tracking point, it would be possible to track a motion during an acquisition. The center of mass could therefore possibly be used as a reference to connect two different time intervals on each side of the moment were the motion occurred. The raw PET data used for this project was acquired in the Nuclear Medicine Department in Karolinska University Hospital in Huddinge and covered four turns of one minute acquisitions in different positions and with two different objects that were saved in list mode. The acquisitions were analyzed with the Siemens software e7-tools and sliced into time intervals. To calculate the center of mass within these time intervals, two methods were developed. One method only used the Siemens software e7-tools and histogrammed the time of flight bin position. The other method used each event position in its sinogram to calculate a center of mass sinusoidal equation. This equation lead to coordinates describing the center of mass in a specific slice. / Ett vanligt problem inom positronemissiontomografiundersökningar av hjärnan är rörelser från patienten. Om patienten rör sitt huvud under undersökningen kommer all förvärvad data inte vara kliniskt lämpad. Detta innebär att en stor del av datan från en PET-undersökning inte används över huvud taget. Rörelsespårning under PET undersökningar av hjärnan är ett relativt outforskat ämne inom medicinsk bildgivning i relation till amplituden av problemet. På grund av strålningsrisken av un- dersökningen och logistiken på sjukhusen, är en andra bildtagning inte att föredra. Därför skulle en metod för att undvika en andra bildtagning vara uppskattad. PET-rådata sparad i list mode möjliggör analys av data inom tidsspektrat av en undersökning. Genom att beräkna det undersökta objektets barocentrum genom att enbart använda rådata sparad i list mode och använda detta som en referenspunkt, så finns en möjlighet att följa en rörelse under en undersökning. Objektets barocentrum skulle kunna fungera som en referenspunkt för att binda ihop två olika tidsegment på varsin sida om tillfället då en rörelse har skett. Rådatan som användes i detta projekt var förvärvad vid nukleärmedicinska avdelningen på Karolinska Universetetssjukhuset i Huddinge och täckte fyra stycken undersökningar på en minut vardera i olika positioner och två olika objekt som sparades i list mode. Datainsamlingarna över- sattes med Siemens-mjukvaran e7-tools och delades sedan upp i tidsegment. För att räkna ut ett barocentrum i dessa tidssegment så utvecklades två metoder. En metod använde sig enbart av Siemens-mjukvaran e7-tools och använde dess funktion ”histogramming” för att dela upp alla events time of flight position. Den andra metoden använde varje events position i dess sinogram för att beräkna en barocentrisk sinusformad funktion. Denna funktion ledde till koordinater som beskrev masscentrum i en specifik skiva.

Syftet med föreliggande studie var att undersöka hur många av orden i en lärobokserie i engelska för årskurserna 4–6 som var bland de mest frekventa orden i det engelska språket. Undersökningen genomfördes med hjälp av två engelska frekvenslistor: General Service List (GSL) och New General Service List (NGSL). NGSL är en uppdaterad version av GSL som använts i tidigare studier och därför ville jag i min studie bl.a. ta skillnaden mellan den äldre och nyare versionen i beaktande. Syftet var således att undersöka hur många av orden i lärobokserien Magic! som förekommer i GSL och NGSL, huruvida antalet unika huvudord i Magic!-seriens tre årskursböcker ökar, och hur ofta de unika huvudorden i böckerna upprepas, med särskilt fokus på substantiv, adjektiv och verb. Analysen utfördes med hjälp av ordprogrammet AntWordProfiler som skannar ord i textfiler för att sedan kategorisera orden utifrån ordlistor kopplade till programmet. Studiens resultat indikerar att samtliga böcker i Magic!-serien innehöll fler ord listade i NGSL än i GSL. Resultatet visade även att den sammanlagda förekomsten av huvudord ökade i varje lärobok, liksom antalet unika huvudord. Bland orden som repeterades minst 10 gånger fanns fler substantiv och verb än adjektiv och alla verben med minst 10 repetitioner gick att hitta i både GSL och NGSL.  Min slutsats är att de unika orden i lärobokserien Magic! överensstämmer bättre med de listade orden i NGSL än dem i GSL. En annan slutsats är att om ordkunskap hade varit ett betygskriterium i ämnet engelska skulle högre krav kunnat ställas på läroboksförfattare att utforma sina böcker med listor över de mest frekventa orden i det engelska språket i åtanke.

Please download dissertation to view abstract.

We have designed, developed, and assessed a novel preclinical positron emission tomography (PET) imaging system named ModPET. The system was developed using modular gamma cameras, originally developed for SPECT applications at the Center for Gamma Ray Imaging (CGRI), but configured for PET imaging by enabling coincidence timing. A pair of cameras are mounted on a exible system gantry that also allows for acquisition of optical images such that PET images can be registered to an anatomical reference. Data is acquired in a super list-mode form where raw PMT signals and event times are accumulated in events lists for each camera. Event parameter estimation of position and energy is carried out with maximum likelihood methods using careful camera calibrations accomplished with collimated beams of 511-keV photons and a new iterative mean-detector-response-function processing routine. Intrinsic lateral spatial resolution for 511-keV photons was found to be approximately 1.6 mm in each direction. Lists of coincidence pairs are found by comparing event times in the two independent camera lists. A timing window of 30 nanoseconds is used. By bringing the 4.5 inch square cameras in close proximity, with a 32-mm separation for mouse imaging, a solid angle coverage of ∼75% partially compensates for the relatively low stopping power in the 5-mm-thick NaI crystals to give a mea- sured sensitivity of up to 0.7%. An NECR analysis yields 11,000 pairs per second with 84 μCi of activity. A list-mode MLEM reconstruction algorithm was developed to reconstruct objects in a 88 x 88 x 30 mm field of view. Tomographic resolution tests with a phantom suggest a lateral resolution of 1.5 mm and a slightly degraded resolution of 2.5 mm in the direction normal to the camera faces. The system can also be configured to provide (99m)Tc planar scintigraphy images. Selected biological studies of inammation, apoptosis, tumor metabolism, and bone osteogenic activity are presented.

This dissertation investigates the application of list-mode data to detection, estimation, and image reconstruction problems, with an emphasis on emission tomography in medical imaging. We begin by introducing a theoretical framework for list-mode data and we use it to define two observers that operate on list-mode data. These observers are applied to the problem of detecting a signal~(known in shape and location) buried in a random lumpy background. We then consider maximum-likelihood methods for the estimation of numerical parameters from list-mode data, and we characterize the performance of these estimators via the so-called Fisher information matrix. Reconstruction from PET list-mode data is then considered. In a process we called "double maximum-likelihood" reconstruction, we consider a simple PET imaging system and we use maximum-likelihood methods to first estimate a parameter vector for each pair of gamma-ray photons that is detected by the hardware. The collection of these parameter vectors forms a list, which is then fed to another maximum-likelihood algorithm for volumetric reconstruction over a grid of voxels. Efficient parallel implementation of the algorithms discussed above is then presented. In this work, we take advantage of two low-cost, mass-produced computing platforms that have recently appeared on the market, and we provide some details on implementing our algorithms on these devices. We conclude this dissertation work by elaborating on a possible application of list-mode data to X-ray digital mammography. We argue that today's CMOS detectors and computing platforms have become fast enough to make X-ray digital mammography list-mode data acquisition and processing feasible.

Subject searching—seeking information with a subject or topic in mind—is often involved in carrying out undergraduate assignments such as term papers and research reports. It is also an important component of information literacy—the abilities and experiences of effectively finding and evaluating, and appropriately using, needed information—which universities hope to cultivate in undergraduates by the time they complete their degree programs. By exploring the subject searching of a small group of upper-level, academically successful undergraduates over a school year I sought to acquire a deeper understanding of the contexts and characteristics of their subject searching, and of the extent to which it was similar in quality to that of search and domain experts. Primary data sources for this study comprised subject searching diaries maintained by participants, and three online subject searches they demonstrated at the beginning, middle, and end of the study during which they talked aloud while I observed, followed by focused interviews. To explore the quality of study participants’ subject searching I looked for indications of advanced thinking in thoughts they spoke aloud during demonstration sessions relating to using strategy, evaluating, and creating personal understanding, which represent three of the most challenging and complex aspects of information literacy. Applying a layered interpretive process, I identified themes within several hundred instances of participants’ advanced thinking relating to these three information literacy elements, with evaluative themes occurring most often. I also noted three factors influencing the extent of similarity between the quality of participants’ advanced thinking and that of search and domain experts which reflected matters that tended to be i) pragmatic or principled, , ii) technical or conceptual, and iii) externally or internally focused. Filtered through these factors, participants’ instances of advanced thinking brought to mind three levels of subject searching abilities: the competent student, the search expert, and the domain expert. Although relatively few in number, I identified at least some advanced thinking evincing domain expert qualities in voiced thoughts of all but one participant, suggesting the gap between higher order thinking abilities of upper-level undergraduates and information literate individuals is not always dauntingly large.

Hensikt: Hensikten med undersøkelsen var å beskrive, og å oppnå større forståelse for, hvordan ventelistepasienter ved Klinikk for ortopedi og revmatologi og pasientrepresentanter fra Brukerutvalget ved St. Olavs Hospital i Trondheim oppfattet ventetiden og kontakten med sykehuset i påvente av undersøkelse og behandling. Kunnskapen skal brukes til å forbedre informasjonen til og kommunikasjonen med ventelistepasientene. Metode: Datainnsamling ble gjort ved 24 individuelle intervju med pasienter fra ventelistene og et gruppeintervju med pasienter i en offisiell rolle som medlemmer av sykehusets Brukerutvalg. Analysen av intervjuene ble gjort med fenomenografisk tilnærming. Resultat: To sammenhengende hovedtema fremkom, der tema om Daglig liv som ventelistepasient dominerte over tema om Informasjon og kommunikasjon i ventetiden. De to tema ble belyst med seks hovedkategorier med til sammen 20 underkategorier som viste at ventelistepasientene opplevde en hverdag med mye smerter og hindringer i forhold til tidligere funksjonsnivå. De var lite opptatt av generell informasjon og hvordan den skriftlige informasjonen så ut. Den informasjon de hadde fått ble oppfattet som grei nok, men inneholdt ikke de opplysninger de hadde behov for. Det viktige var å få personlig, lett forståelig og forklarende informasjon av legen ved den polikliniske undersøkelsen der de eventuelt ble søkt til innleggelse og operasjon; på et tidlig tidspunkt i ventetiden få en konkret operasjonsdato å forholde seg til; få målrettet informasjon om hvordan de kunne forberede seg på operasjonen og tilrettlegge for seg selv etter operasjonen; at det var noen å komme i kontakt med hvis de ønsket det. I tillegg til samsvarende oppfatninger med ventelistepasientene var deltakerne fra Brukerutvalget mer opptatt av og kritisk til informasjonens innhold og form enn pasientene i de 24 individuelle intervjuene. Konklusjon: Pasientene ønsket kontroll over livet i ventetiden ved å få konkret og personlig informasjon om operasjonsdato, hensiktsmessige forberedelser, hva og hvordan i forhold til operasjon og rekonvalesens. Først når dette var oppfylt kunne de vise en begrenset interesse for informasjonens utforming / Aim: The aim of the study was to describe and achieve a greater understanding of how patients on the waiting list for surgery at the Department of Orthopaedic Surgery and Rheumatology and the group of patient representatives (Brukerutvalget) at St. Olav’s University Hospital in Trondheim experienced the waiting time and the contact with the hospital. The knowledge shall be used to improve the information to and the communication with patients on waiting list. Method: The data collection was done through 24 individual interviews with patients on waiting lists and one group interview with four of the patients having an official role as members of the hospital’s group of user representatives. The analysis of the interviews was done by a phenomenographic approach. Results: Two related main subjects appeared of which the subject of the daily life as a waiting list patient dominated over the subject of the information and communication received during the waiting time. These two subjects were illustrated by six main categories and 20 subcategories which showed that the waiting list patients experienced a daily life with much pain and hindrances compared to their earlier level of functionality. They were to a small degree interested in any general information and how the general information was presented. The information they had received was conceived as satisfactory, but did not contain the information they needed. The important thing was to get personal, easy to understand and well explained information from the doctor during the visit at the outpatient clinic, when they were eventually sought referred to the hospital for admission and operation, to get a fixed time for the operation early in the waiting time, to get systematic information about how to prepare for the operation and how to organize themselves after the operation, and finally that there should be a person to contact if they needed to. In addition to perceptions common with the waitinglist patients the participants from the group of user representatives were more concerned with and critical to the contents and presentation of the information than the patients from the 24 individual interviews. Conclutions: Personal and relevant information was needed to cope with the daily life. Not till the patients knew about a fixed time for the operation, appropriate preparations, the surgery and convalescence they could show a limited interest for the shaping of the information / <p>ISBN 978-91-85721-15-3</p>

One channel model that characterises multipath fading effect of a wireless channel is called Flat Rayleigh Fading channel model. Given the properties of Flat Rayleigh Fading channel, an equation to find the capacity of a Flat Rayleigh fading channel with hard decision decoding is derived. The difference of power requirement to achieve the Additive White Gaussian Noise (AWGN) capacity over a Flat Rayleigh Fading channel fading is found to increase exponentially with Es /N0 . Upper and lower bounds of error performance of linear block codes over a Flat Rayleigh Fading channel are also studied. With the condition that the excess delay of a channel is known earlier, it is shown that a correlator with shorter length, according to excess delay of the channel, can be constructed for use in wireless channel response measurements. Therefore, a rule of construction of a shorter length correlator is defined, involving concatenation of parts of a Constant Amplitude Zero Auto-Correlation (CAZAC) sequence. Simulation of [136,68,24] Double Circulant Code with Dorsch List Decoding is also done in order to evaluate error performance of the channel coding scheme over one of the IEEE Wireless Metropolitan Area Network (WirelessMAN) channel models, the Stanford University Interim Channel Model No. 5 (SUI-5) channel. Performance of the channel cod- ing was severely degraded over the SUI-5 channel when it is compared to its performance over the AWGN channel. Indoor path losses within three multifloor office buildings were investigated at 433 MHz, 869 MHz and 1249 MHz. The work involved series of extensive received signal strength measurements within the buildings for all of the considered frequencies. Results have shown that indoor path loss is higher within a square footprint building than indoor path loss in a rectangular building. Parameters of Log-Distance Path Loss and Floor Attenuation Factor Path Loss models have been derived from the measurement data. In addition, a new indoor path loss prediction model was derived to cater for path loss pre- diction within multifloor buildings with indoor atriums. The model performs with better prediction accuracy when compared with Log-Distance Path Loss and Floor Attenuation Factor Path Loss models.