Anyons on Higher Genus Surfaces - a Constructive Approach

We reconsider the problem of anyons on higher genus surfaces by embedding them in three dimensional space. From a concrete realization based on three dimensional flux tubes bound to charges moving on the surface, we explicitly derive all the representations of the spinning braid group. The component structure of the wave functions arises from winding the flux tubes around the handles. We also argue that the anyons in our construction must fulfil the generalized spin-statistics relation.Comment: 8 pages, LaTex, 2 figures available on request ([email protected]), USITP-93-1

Design and evaluation of a distributed control architecture over switched Ethernet in active filters

The area of power quality has received more and more attention during the last decade. Poor power quality is a growing problem, especially for the industry because it has a negative effect on production efficiency, power consumption and equipment life-span. Active filters are one of the more widespread solutions to these problems. An active filter is often sized and installed to compensate a specific load, based on a preceding power quality measurement. Often one system is not enough and multiple parallel systems must be used. This thesis investigates if it is possible to design a distributed control system where a number of filters work together and communicate using a switched Ethernet network. Such a distributed system can offer advantages such as better coordination and simplified configuration and operation. In the resulting distributed system the control tasks are split into two groups, power quality controllers and hardware controllers. The power quality controllers are executed by a master control computer and the resulting setpoint is distributed through the network to a number of slaves. The distributed system has been tested both through simulations and in a real-world implementation. Based on these tests it can be concluded that the distributed system works and that its performance is only marginally affected compared to the original system

Methods to reduce capital tied up in Stora Enso Bioenergy terminal stocks

Stora Enso Bioenergi AB producerar, köper och säljer skogsbränsle till i huvudsak energibolag och skogsindustriföretag. Marknaden för biobränsle är starkt säsongsbetonad och den största efterfrågan infinner sig under den kalla delen av året, mellan oktober och april. Det innebär att behovet av produktionsresurser får en mycket ojämn fördelning över året. Genom att använda terminallager kan behovet av produktionsresurser fördelas under en längre period. Det medför dock en hög kapitalbindning i terminallagren. En för hög kapitalbindning är inte optimalt bland annat eftersom kapitalet alternativt skulle kunna investeras i något annat, där det skulle ge en högre avkastning. Detta examensarbete syftar därmed till att utveckla en metod för att minska kapitalbindningen i Stora Enso bioenergis terminallager. Studien är avgränsad till att omfatta distrikt sydöst då det väntas ge en god avspegling av hela företagets terminalanvändning. En nulägesanalys har genomförts genom informella intervjuer med anställda, litteratursökning och genom insamling och analys av data över terminalflöden. Analysen av terminalanvändningen visar att distrikt sydöst har en lageromsättningshastighet uppgående till 2,3 gånger per år i terminallagren. Beräknat på distriktets samtliga leveranser, inkluderat de leveranser som går direkt till kund, är lageromsättningshastigheten 8,1 gånger per år. Under högsäsongen, mellan oktober och april, lagras materialet i genomsnitt 14,6 veckor på terminal innan det levereras till kunden. Beräkningar visar att lagerföringskostnaden i genomsnitt uppgår till omkring 13,2 kronor per lagrad kubikmeter. Det tyder på att så länge extrakostnaden för att höja flisningskapaciteten understiger 13,2 kronor per kubikmeter är det ekonomiskt lönsamt att använda extra kapacitet istället för terminallagring. För kunder med specifika krav som försörjs från Åtvidabergs terminal visar beräkningar att den optimala tillredningskvantiteten för år 2010 är 1 394 MWh under perioden november till mars och 423 MWh under övrig tid. En stängning av Virserums terminal föreslås. Detta beräknas att ge en besparing av administrativa och fasta kostnader uppgående till omkring 50 000 kronor. Vidare föreslås en sammanslagning av antalet sortiment som lagras på terminal samt en minskning av lagernivåerna på barkstation Kisa. Sammanlagt väntas åtgärderna minska kapitalbindningen i terminallagren med omkring 680 000 kronor. Kapitalbindningen i terminallagren bör övervakas genom att mäta och sätta upp måltal i syfte att öka lageromsättningshastigheten på varje terminal

The Potential Role of Ammonia as Marine Fuel-Based on Energy Systems Modeling and Multi-Criteria Decision Analysis

To reduce the climate impact of shipping, the introduction of alternative fuels is required. There is a range of different marine fuel options but ammonia, a potential zero carbon fuel, has recently received a lot of attention. The purpose of this paper is to assess the prospects for ammonia as a future fuel for the shipping sector in relation to other marine fuels. The assessment is based on a synthesis of knowledge in combination with: (i) energy systems modeling including the cost-effectiveness of ammonia as marine fuel in relation to other fuels for reaching global climate targets; and (ii) a multi-criteria decision analysis (MCDA) approach ranking marine fuel options while considering estimated fuel performance and the importance of criteria based on maritime stakeholder preferences. In the long-term and to reach global GHG reduction, the energy systems modeled indicate that the use of hydrogen represents a more cost-effective marine fuel option than ammonia. However, in the MCDA covering more aspects, we find that ammonia may be almost as interesting for shipping related stakeholders as hydrogen and various biomass-based fuels. Ammonia may to some extent be an interesting future marine fuel option, but many issues remain to be solved before large-scale introduction

Development of a pressure-measuring device to optimize compression treatment of lymphedema and evaluation of change in garment pressure with simulated wear and tear.

The use of compression garments in treating lymphedema following treatment of genital (penis, testes, uterus, cervical) and breast cancer treatment is a well-established practice. Although compression garments are classified in compression classes, little is known about the actual subgarment pressure exerted along the extremity. The aims of this study were to establish an in vitro method for measuring subgarment pressure along the extremity and to analyze initial and over time subgarment pressure of compression garments from three manufacturers. The measurements were performed with I-scan(®) (Tekscan Inc.) pressure measuring equipment once a week during a period of 4 weeks. Wear and tear was simulated by washing and putting on the garments on plastic legs every day. There was a statistically significant difference between the garments of some of manufacturers. There was no difference between garments from the same manufacturer. No significant decrease of subgarment pressure was observed during the trial period. The study demonstrated that Tekscan pressure-measuring equipment could measure subgarment pressure in vitro. The results may indicate that there was a difference in subgarment pressure exerted by garments from different manufacturers and that there was no clear decrease in subgarment pressure during the first four weeks of usage

Psychometric testing of a Swedish version of the Apathy Evaluation Scale

Background: Apathy, a prevalent and clinically relevant symptom in neurodegenerative disease, is often evaluated by the instrument Apathy Evaluation Scale (AES). However, this instrument has not been translated into Swedish, halting clinical and research efforts. Furthermore, previous studies lack analyses of some basic properties, such as the legitimacy of a total score, or have analysed dimensionality by questionable methods.Aim: To translate and psychometrically evaluate a Swedish version of the AES.Method: The AES was translated, and its psychometric properties were tested in the Swedish BioFINDER study, including cognitively well elderly, and subjects with mild cognitive or parkinsonian symptoms. Psychometric analyses were conducted according to classical test theory (CTT) and aimed to resemble those performed in the English original study by Marin et al. in 1991. Dimensionality was additionally analysed on a matrix of polychoric correlations and parallel analyses.Results: Data indicate that the Swedish AES performs satisfactorily regarding data completeness, scaling assumptions, targeting, and reliability. Principal component analyses (with parallel analysis) of polychoric correlation matrices identified a single component. Convergent and discriminative validity correlations accorded with a priori expectations.Conclusions: The study provides initial support that this Swedish AES performs similarly to the English original, and exhibits acceptable psychometric properties according to CTT, including supported unidimensionality, and may be adopted for use in clinical and research settings.Keywords: Apathy, Apathy Evaluation Scale (AES), neurodegenerative disease, neuropsychiatric assessment, psychometric

Järnväg på bro - Är det lönsamt att bygga järnväg på bro istället för på marken?

The thesis questions whether it is possible to justify an elevated railway solution instead of using cut and fill techniques. The report describes the construction techniques followed by different socio-economic effects such as maintenance, barrier effect and land claims. Construction time and construction costs for a number of traditional railway and elevated railway projects are presented in the report. An assessment of the socio-economic impact along with construction costs is made to answer this question

Alterations of matrix metalloproteinases in the healthy elderly with increased risk of prodromal Alzheimer's disease

INTRODUCTION: Matrix metalloproteinases (MMP) are believed to be involved in the pathologic processes behind Alzheimer's disease (AD). In this study, we aimed to examine the cerebrospinal fluid (CSF) levels of MMPs and tissue inhibitors of metalloproteinase-1 (TIMP-1) in individuals with AD dementia and cognitively healthy elderly individuals, and to investigate their relationship with established CSF biomarkers for Alzheimer's disease.METHODS: CSF was collected from 38 individuals with AD dementia and 34 cognitively healthy elderly individuals. The CSF was analyzed for MMP-1, MMP-3, MMP-9, TIMP-1, beta-amyloid1-42 (Abeta42), total tau protein (T-tau) and phosphorylated tau protein (P-tau). MMP/TIMP-1 ratios were calculated. APOE genotype was determined for the participants.RESULTS: AD patients had higher MMP-9/TIMP-1 ratios and lower TIMP-1 levels compared to cognitively healthy individuals. In AD patients, the MMP-9/TIMP-1 ratio correlated with CSF T-tau, a marker of neurodegeneration. Interestingly, the cognitively healthy individuals with risk markers for future AD, i.e. AD-supportive CSF biomarker levels of T-tau, P-tau and Abeta42 or the presence of the APOE epsilon4 allele, had higher CSF MMP-3 and MMP-9 levels and higher CSF MMP-3/TIMP-1 ratios compared to the healthy individuals without risk markers. The CSF levels of MMP-3 and -9 in the control group also correlated with the CSF T-tau and P-tau levels.CONCLUSIONS: This study indicates that MMP-3 and MMP-9 might be involved in early pathogenesis of AD and that MMPs could be associated with neuronal degeneration and formation of neurofibrillary tangles even prior to development of overt cognitive dysfunction