Through Spherical Harmonics, one can describe complex gravitational fields. However as the order and degree of the spherical harmonics increases, the computation speed rises exponentially. In addition, for onboard applications of spherical harmonics, the processors are radiation hardened in order to mitigate negative effects of the space environment on electronics. But, those processors have outdated processing speeds, resulting in a slower onboard spherical harmonic program. This thesis examines a partial solution to the slow computation speed of spherical harmonics programs. The partial solution was to supplant the gravity models in the flight software. The spherical harmonics gravity model can be replaced by a hybrid model, a mass concentrations model and a secondary (lesser degree or order) spherical harmonics model. That hybrid model can lead to greater processing speeds while maintaining the same level of accuracy. To compute the mass values for the mass concentration model, a potential estimation scheme was selected. In that scheme, mass values were computed by minimizing the integral of the difference between the correct and the estimated potential. The best hybrid model for the 8 degree and 8 order, 15 degree and 15 order, and 30 degree and 30 order lunar potential fields is developed following three different approaches: potential zeros method, gravitational anomalies method, and iterative method. Afterwards, the accuracy and computation time of the models are measured and compared to the primary spherical harmonic lunar model. In the aftermath, while the best hybrid model for all three cases was able to run faster than the primary spherical harmonic model, it was unable to be sufficiently accurate to replace the primary spherical harmonic model. The mass estimation scheme is severely hindered by the condition number and convergence issues resulting in inaccurate estimates for the mass values for a given distribution. It is recommended to alleviate the condition number error by eliminating the inverse in the mass estimation scheme. Other recommendations include fixing the convergence error, investing in software and hardware development, and focusing on other hybrid research objectives.

Most part of my thesis is devoted to efficient automated logic synthesis of oracle processors. These Oracle Processors are of interest to several modern technologies, including Scheduling and Allocation, Image Processing and Robot Vision, Computer Aided Design, Games and Puzzles, and Cellular Automata, but so far the most important practical application is to build logic circuits to solve various practical Constraint Satisfaction Problems in Intelligent Robotics. For instance, robot path planning can be reduced to Satisfiability. In short, an oracle is a circuit that has some proposition of solution on the inputs and answers yes/no to this proposition. In other language, it is a predicate or a concept-checking machine. Oracles have many applications in AI and theoretical computer science but so far they were not used much in hardware architectures. Systematic logic synthesis methodologies for oracle circuits were so far not a subject of a special research. It is not known how big advantages these processors will bring when compared to parallel processing with CUDA/GPU processors, or standard PC processing. My interest in this thesis is only in architectural and logic synthesis aspects and not in physical (technological) design aspects of these circuits. In future, these circuits will be realized using reversible, nano and some new technologies, but the interest in this thesis is not in the future realization technologies. We want just to answer the following question: Is there any speed advantage of the new oracle-based architectures, when compared with standard serial or parallel processors?

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BACKGROUND: Schizophrenia is a diverse disorder comprising positive, negative, and cognitive symptoms. While several cognitive domains have been alleged to influence symptom severity and quality of life, impaired information processing speed (IPS) is the most profoundly affected and is present even before a diagnosis of a psychotic disorder. Although extensively studied, reliable and reproducible pathological neural circuitry leading to cognitive dysfunction has yet to be fully identified or understood. OBJECTIVE: Our study seeks to identify the neurobiological connections responsible for diminished processing speed in a group of patients with psychotic disorders and a group of individuals at risk to develop a psychotic disorder. METHODS: This data-driven evaluation of resting-state fMRI data and cognitive testing considers two populations: one cohort of adults diagnosed with psychotic disorders and another cohort of individuals identified as being at risk for developing psychotic disorders (ShangHai At-Risk for Psychosis). The images were processed and evaluated using multivariate pattern analysis (MVPA) to compare brain connectivity to information processing speed. The MVPA calculations generated a map to determine the regions where brain connectivity has the strongest correlation to information processing speed as measured by the Brief Assessment in Cognition for Schizophrenia (BACS). RESULTS: The results of the cognitive assessments demonstrate that information processing speed (IPS) is the most impaired domain of cognition in adults with psychotic disorders. Multivariate distance matrix regression (MDMR) was used to identify the cerebellum as the specific brain location where connectivity was most strongly correlated to information processing speed. Specifically, the cerebellar (CBM) connectivity to the dorsal medial prefrontal cortex (dmPFC) exhibited the strongest positive correlation with IPS. The cohort of individuals diagnosed with a psychotic disorder (n = 103) exhibited a moderately strong relationship (r = 0.396, p = 0.000036) between the CBM-dmPFC coactivation and IPS. This finding was then replicated in the SHARP dataset. The clinical high risk sample (n = 137) also identified the CBM-dmPFC circuit as the strongest correlation to information processing speed (r=0.39, p = 0.000002057). Furthermore, the CBM-dmPFC circuit relationship to IPS became stronger as we considered the most impaired subjects. Individuals who would go on to be diagnosed with a psychotic disorder (converters, n = 19) exhibited the strongest relationship between CBM-dmPFC and information processing speed (r = 0.56, p = 0.01). CONCLUSIONS: The reduction in functional connectivity between cerebellum and dmPFC appears to be critically related to the generalized decrease in information processing speed in patients with psychotic disorders and patients at risk of developing a psychotic disorder in the future. The finding is reproduced in two culturally, linguistically, and geographically disparate populations. Interestingly, the finding demonstrates a link between the functional dysconnectivity and cognitive dysfunction in the years before and during the onset of a diagnosis of a psychotic disorder. The research indicates a diagnostic role for assessing information processing speed to identify prodromal patients at risk of developing a psychotic disorder. Finally, the identification of a specific neurological circuit related to impaired cognition would provide a therapeutic target to alleviate cognitive deficits in patients with psychotic disorders in the future.

Learning and memory impairments are among the most common and enduring cognitive consequences of traumatic brain injury (TBI). Researchers have yet to reach a consensus with regard to the basic cognitive mechanism underlying new learning and memory disturbances after TBI. The purpose of the present study was to investigate the current views regarding the cognitive processes thought to explain impairments in verbal learning and memory subsequent to brain injury. Specifically, this study sought to examine the roles of the central executive component of working memory and processing speed in verbal learning ability following TBI. Latent variable structural equation modeling (SEM) was used to analyze the data of 70 post-acute care TBI patients between the ages of 16 and 65, who completed a full neuropsychological evaluation. Results indicated that verbal learning and memory difficulties following TBI were explained primarily in terms of the central executive aspects of working memory, after accounting for the relative contributions of processing speed in the model. The direct effect of processing speed on verbal learning and memory was not significant when working memory was taken into account in the model. Rather, the effects of processing speed on verbal learning ability were largely indirect through the central executive component of working memory. Results highlight the importance of both working memory and processing speed in supporting verbal learning and memory processes after TBI. Practical implications for targeting remediation efforts and directing approaches to memory rehabilitation are discussed in light of the study’s findings. / text

The study examines language, memory and reading skills in children from two private schools in Victoria, British Columbia. Phonological processing and word-level decoding were significantly correlated, suggesting that familiarity with letters and their associated sounds are important for word-level reading. Phonological processing and decoding skill performance were significantly correlated with STM span and not WM span, suggesting that word-level decoding is not attentionally demanding for this sample of children. Decoding speed was inversely related to STM span; faster reading times and larger STM spans were highly predictive of one another. The children’s WM and STM task performance were relatively similar and may be reflective of efficient strategy use, such as word recognition, which reduces attention for processing in WM.

The purpose with the study is to provide a basis for an implementable, improved returns management process. This will help to obtain an empirical result for Lager 157 and to fill any scientific knowledge gap. The study has been divided into two research questions that are of a hierarchical nature. The authors first want to map the return process in order to then make suggestions for improvements using collected data along with collected theory. Method – A single case study has been conducted because the authors are studying a process and want a more in-depth knowledge. The study is carried out on Lager 157, who is active in fashion retailing and has a pronounced strategy for omnichannels, where they use both stores and e-commerce. Because the study only is made on one company, the external validity will be low. But the authors will compare collected theory with the empirics, which will increase the external validity. The literature has been collected through different sources, such as; databases, snowballing and recommendations from teachers and fellow students. The methods for collecting data has been; interviews, observations and document studies. Triangulation of data has ensured that the collected data is correct. Findings – The authors have, together with data and theory, provided a basis on how the study company could improve their returns management. The basis stated is that a web-based return registration should be implemented early in the process but also that the stores should use the same ERP as they do in the e-commerce department. These suggestions are based on that the study company should highlight activities such as gatekeeping and return avoidance, which leads to an improved returns management. Because of these changes, the company can increase their process speed but also improve their process integration and take a step towards fully integrated omni channels. Implications –The study has provided with both empirical and scientific implications. The study company has, from the results, got an overview of their returns management but also been provided with suggestions that can lead to an improved returns management in the future. In the results, the study company can also see which effects these suggestions could have and see how the new returns management could look like compared to have it looked before. During the literature study, the authors found that research connected to omni channels and the focused area were missing. Based on this the authors have created a model which illustrates what the companies should prioritize. Because the study only is made on one single company, the authors thinks that there is room for further research where the model could be evaluated and evolved to fit a greater number of companies. Limitations – Because of a time limit of the study, a single case study was considered to be of high relevance. It gave the authors the opportunity to use different methods to collect data in order to strengthen the results obtained. The external validity would have been higher if an multi case study would have been conducted with a quantitative approach. The interviews where following a semi-structured structure because the authors wanted to gather a large amount of information and leave space for follow-up questions. The observations were unstructured in order to make sure that the observation object where acting naturally. On the other hand, a structured observation would have shown differences and deviations in the activities. The document studies were only used to find out which type of data that the study company did collect. This could have been more extensive in a quantitative focus on the study. / Syfte – Syftet med studien är att ta fram underlag för en implementerbar, förbättrad returprocess. Detta skall bidra till att få fram ett empiriskt resultat åt Lager 157 samt att fylla igen eventuella vetenskapliga kunskapsgap. Studien har delats in i två forskningsfrågor av en hierarkisk karaktär. Författarna vill först kartlägga returprocessen för att i sedan ta fram underlag för förbättringar med hjälp av insamlade data tillsammans med insamlad teori. Metod – En enfallsstudie har genomförts då författarna ämnar studera en process och vill ha en mer djupgående kunskap. Studien är genomförd på Lager 157 som är verksamma inom mode och har en uttalad strategi för omnihandel, där de använder sig av både butiker och e-handel. Då studien enbart är genomförd på ett fallföretag så kommer den externa validiteten vara låg. Däremot ämnar författarna jämföra insamlad teori med empirin, vilket stärker den externa validiteten. Författarna har samlat in litteratur genom olika tillvägagångssätt, såsom; databassökningar, snöbollsmetoden samt rekommendationer ifrån handledare och medstudenter. De metoder som har använts för att samla in data är; intervjuer, observationer och dokumentstudier. Triangulering av data har säkerställt att den insamlade data är korrekt. Resultat – Tillsammans med insamlade data och teori har författarna tagit fram underlag för hur fallföretaget skulle kunna förbättra sin process. Det underlag som tagits fram är dels att en webbaserad returregistrering bör implementeras tidigt i flödet samt att butikerna och e- handeln bör använda sig av samma affärssystem. Detta underlag har sin grund i att fallföretaget bör lyfta fram aktiviteter så som gatekeeping och return avoidance, vilket leder till en förbättrad returprocess. Effekterna anses bidra till att fallföretaget kan öka sin bearbetningshastighet men också förhöja sin processintegration och ta ett steg mot en fullt integrerad omnihandel. Implikationer – Studien har både tagit fram empiriska och vetenskapliga implikationer. Dels har fallföretaget utifrån studiens resultat fått en överblick i hur returprocessen ser ut men också fått ett underlag med åtgärdsförslag som kan leda till en förbättrad returprocess i framtiden. I studiens resultat kan fallföretaget se vilka effekter detta kan mynna ut i men också hur det nya flödet skulle komma att se ut i de båda kanalerna. Då forskning inom omnihandel kopplat till det studerade området ansågs saknas så har författarna tagit fram en modell som illustrerar vad företag bör prioritera. På grund av att studien enbart är genomförd på ett företag anser forskarna att det finns ett tillfälle för vidare forskning, där modellen kan utvärderas och utvecklas för att passa ett större antal företag. Begränsningar – Då författarna har en tidsbegränsning kopplat till arbetet ansåg författarna att en enfallstudie var av högst relevans. Detta gav även möjligheten för författarna att ta användning av olika datainsamlingstekniker för att stärka de resultat som tagits fram. Om en flerfallstudie hade genomförts med mer kvantitativ datainsamling hade det gett en mer överblickande bild, vilket skulle kunna stärka den externa validiteten. De intervjuer som genomfördes följde en semistrukturerad struktur då författarna ämnade att samla in en stor mängd information och där utrymme fanns för följdfrågor. De observationer som genomfördes var ostrukturerade för att säkerställa att observationsobjekten betedde sig naturligt. Däremot hade en strukturerad observation visat på skillnader och avvikelser i aktiviteterna. Dokumentstudierna användes enbart för att säkerställa vilken typ av data som samlades in i dagsläget och kunde ha varit mer omfattande vid en kvantitativ inriktning på studien.

Due to various shortcomings of the visual system, some visual stimuli can only be identified with 100% accuracy if they are shown for a certain amount of time. This time can be measured using the Inspection Time (IT) paradigm. In an IT task, a “pi” figure with differing leg lengths is typically presented briefly (e.g., 20-200 ms) and is then immediately masked to prevent retinal afterimages. Participants are subsequently required to choose which of the two legs was longer. The objective of this task is to determine the shortest amount of time the pi figure needs to be shown for it to be perceived with 80% accuracy. Given that visual processing has been shown to be altered during and /or prior to a movement, the present experiment sought to test how the requirement to perform a motor task affected IT. Twenty-eight participants took part in the experiment, which was comprised of three conditions: no-movement (NM), peak velocity (PV), and foreperiod (FP). In the NM condition, participants grasped a manipulandum and engaged in the IT paradigm. At the end of every trial, participants verbally stated which leg they believed was longest. In the PV condition participants made a rapid movement to a target, and the IT stimulus was presented when their limb reached peak velocity. Finally in the FP condition the IT stimulus was presented during foreperiod (FP). In all three conditions the IT stimulus was randomly presented from between 15-105 ms (in 15 ms increments) and masked for 400 ms. Results showed no significant differences on the IT task between the NM and FP conditions, suggesting no visual upregulation during foreperiod. However, IT performance was significantly poorer in the PV condition in comparison to both the NM and FP condition, suggesting a visual downregulation at that particular movement kinematic.