Network failures can originate from or be located in any one of several network layers as described by the OSI model. This investigation focuses on the role of physical topological design parameters in determining network reliability and performance as can be expected from the point of view of a typical client-server based connection in an Ethernet local area network. This type of host-to-host IP connection is found in many commercial, military and industrial network based systems. Using Markov modelling techniques reliability and performability models are developed for common network topologies based on the redundancy mechanism provided by IEEE spanning tree protocols. The models are tested and validated using the OPNET network simulation environment. The reliability and performability metrics calculated from the derived models for different topologies are compared leading to the following conclusions. The reliability of the entry-nodes into a redundant network is a determining factor in connection availability. Redundancy mechanisms must be extended from the entry-node to the connecting hosts to gain a significant benefit from redundant network topologies as network availability remains limited to three-nines. The hierarchical mesh network offers the highest availability (sevennines) and performability. Both these metrics can be accurately predicted irrespective of the position of the entry-node in the mesh. Ring networks offer high availability (five to sevennines) and performability if the ring remains small to medium sized, however for larger rings (N≥32) the availability is highly dependant on the relative position of the entry-node in the ring. Performability also degrades significantly as the ring size increases. Although star networks offer predictable and high performability the availability is low (four-nines) because of the lack of redundancy. The star should therefore not be used in IP networked systems requiring more than four-nines availability. In all the topologies investigated the reliability and performability can be increased significantly by introducing redundant links instead of single links interconnecting the various nodes, with the star topology availability increasing from four-nines to seven-nines and performance doubling. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2014

Network failures can originate from or be located in any one of several network layers as described by the OSI model. This investigation focuses on the role of physical topological design parameters in determining network reliability and performance as can be expected from the point of view of a typical client-server based connection in an Ethernet local area network. This type of host-to-host IP connection is found in many commercial, military and industrial network based systems. Using Markov modelling techniques reliability and performability models are developed for common network topologies based on the redundancy mechanism provided by IEEE spanning tree protocols. The models are tested and validated using the OPNET network simulation environment. The reliability and performability metrics calculated from the derived models for different topologies are compared leading to the following conclusions. The reliability of the entry-nodes into a redundant network is a determining factor in connection availability. Redundancy mechanisms must be extended from the entry-node to the connecting hosts to gain a significant benefit from redundant network topologies as network availability remains limited to three-nines. The hierarchical mesh network offers the highest availability (sevennines) and performability. Both these metrics can be accurately predicted irrespective of the position of the entry-node in the mesh. Ring networks offer high availability (five to sevennines) and performability if the ring remains small to medium sized, however for larger rings (N≥32) the availability is highly dependant on the relative position of the entry-node in the ring. Performability also degrades significantly as the ring size increases. Although star networks offer predictable and high performability the availability is low (four-nines) because of the lack of redundancy. The star should therefore not be used in IP networked systems requiring more than four-nines availability. In all the topologies investigated the reliability and performability can be increased significantly by introducing redundant links instead of single links interconnecting the various nodes, with the star topology availability increasing from four-nines to seven-nines and performance doubling. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2014

Cities throughout Europe, including Växjö, a college city in the south of Sweden, have been developing and managing their city brands actively to attract young talents and students. Växjö has been a destination for students from Sweden and all over the world to study in Linnaeus University (LNU). However, the city, and according to its managers, has not been able to keep students in it after completing their studies. There are many previous studies that focus on destination and place marketing in general, however, only a few highlight the topic of city brands and branding.   This research has been conducted in order to explore the factors that can contribute to Linnaeus University students’ (customers) satisfaction with the city of Växjö, and examine the relationship between Customer satisfaction and Customer retention and Intention to switch in relative to Växjö. Qualitative and quantitative methods have been used. The primary data for this research has been collected through an online questionnaire survey from 84 LNU students who fitted the target sample criteria, and 6 semi-structured interviews. The findings of this research suggest that majority of the students are satisfied with Växjö as they take their current situation as students into consideration, however, they have shown a low rate of city retention, and a high rate of intention to switch to another place in future. The results are limited to the city of Växjö.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper describes the status of the Edwards Digital Switch (EDS) [1] and the success of the Digital Switch Sustainment Program (DSSP); a multi-service program aimed at cost-effective means for providing maintenance and development of an advanced digital switching system. This digital communications switching system is deployed at the mission control centers of Edwards AFB, Eglin AFB, and China Lake Naval Air Warfare Center (NAWC). Each system provides the test ranges with mission-critical voice communications and Time Space Position Information (TSPI) switching. Through user-friendly Graphical User Interfaces (GUIs), the switch provides exceptional resource management of radios, telephones, user positions, secure communications, radars, trackers, 4-wire Ear & Mouth (E&M) devices, subscriber services, and other equipment. Developed using commercial equipment, such as the Lucent Technologies Digital Access and Cross-Connect System (DACS) II, the digital switch can integrate and interface with the technologies of other test ranges and customers. The DSSP sustaining engineering contract, a $10M contract awarded in 1997, is a multi-service effort in supporting cost effective maintenance and enhancement for the systems’ software and hardware. Eglin and China Lake have agreed to participate in a Digital Switch Working Group (DSWG) to ensure that this configuration management is in place and that all players follow the same system migration path. These ranges and other interested ranges that agree to purchase systems off the contract and participate in the working group will continue to derive benefits by reducing overhead and eliminating the duplication of effort involved in separate endeavors.

Statistical mechanics has been applied to a wide range of systems in physics, biology, medicine and even anthropology. This theory has been recently used to model the complex biochemical processes of gene expression and regulation. In particular, genetic networks offer a large number of interesting phenomena, such as multistability and oscillatory behaviour, that can be modelled with statistical mechanics tools. In the first part of this thesis we introduce gene regulation, genetic switches, and the colonization of a spatially structured media. We also introduce statistical mechanics and some of its useful tools, such as the master equation and mean- field theories. We present simple examples that are both pedagogical and also set the basis for the study of more complicated scenarios. In the second part we consider the exclusive genetic switch, a fundamental example of genetic networks. In this system, two proteins compete to regulate each other's dynamics. We characterize the switch by solving the stationary state in different limits of the protein binding and unbinding rates. We perform a study of the bistability of the system by examining its probability distribution, and by applying information theory techniques. We then present several versions of a mean field theory that offers further information about the switch. Finally, we compute the stationary probability distribution with an exact perturbative approach in the unbinding parameter, obtaining a valid result for a wide range of parameters values. The techniques used for this calculation are successfully applied to other switches. The topic studied in the third part of the thesis is the propagation of a trait inside an expanding population. This trait may represent resistance to an antibiotic or being infected with a certain virus. Although our model accounts for different examples in the genetic context, it is also very useful for the general study of a trait propagating in a population. We compute the speed of expansion and the stationary population densities for the invasion of an established and an expanding population, finding non-trivial criteria for speed selection and interesting speed transitions. The obtained formulae for the different wave speeds show excellent agreement with the results provided by simulations. Moreover, we are able to obtain the value of the speeds through a detailed analysis of the populations, and establish the requirements for our equations to present speed transitions. We finally apply our model to the propagation in a position-dependent fitness landscape. In this situation, the growth rate or the maximum concentration depends on the position. The amplitudes and speeds of the waves are again successfully predicted in every case.

Large-scale changes are common in genomes, and are often associated with pathological disorders. In the work presented in this dissertation, I provide insights into how inverted repeat sequences in budding yeast fuse during replication. Fusion leads to the formation of dicentric chromosomes, a translocation, and other chromosomal rearrangements.Using extensive genetics and some molecular analyses, I demonstrate that dicentric chromosomes are key intermediates in genome instability of a specific chromosome in budding yeast. I provide three pieces of evidence that is consistent with this conclusion. First, I detect a recombination fusion junction that is diagnostic of a dicentric chromosome (using a PCR technique). Second, I show a strong correlation between the amount of the dicentric fragment and the frequency of instability of the entire chromosome. Third, I demonstrate that a mutant known to stabilize dicentric chromosomes suppress instability. Based on these observations, I conclude that dicentric chromosomes are intermediates in causing genome instability in this system.Next, we demonstrate that fusion of inverted repeats is general. Both endogenous and synthetic nearby inverted repeats can fuse. Using genetics, I also show that many DNA repair and checkpoint pathways suppress fusion of nearby inverted repeats and genome instability. Based on our analysis, we propose a novel mechanism for fusion of inverted repeats that we term `faulty template switching.'Lastly, I discuss two genes that are necessary for fusion of nearby inverted repeats. I identified a mutant of the Exonuclease 1 (Exo1) and a mutant of anaphase inhibitor securin (Pds1) that suppress nearby inverted repeat fusion and genome instability. Studies of Exo1 and Pds1 provide us with insights into the molecular mechanisms of fusion.Our finding that nearby inverted repeats can fuse to form dicentric chromosomes that lead to genome instability may have great implications. The generality of this fusion reaction raises the possibility that dicentric chromosomes formed by inverted repeats can lead to genome instability in mammalian cells, and thereby contribute to a cancer phenotype.

No description available.

Forskningsproblem: Det har uppmärksammats en ökad oro bland Big 4-byråerna över den tilltagande konkurrensen på revisionsmarknaden och tendensen att bolag väljer att byta revisionsbyrå mer frekvent. Det finns ett behov i att förklara varför bolag väljer att frivilligt byta revisionsbyrå. Syfte: Syftet med studien är att förklara varför bolag frivilligt väljer att byta revisionsbyrå. Metod 15 hypoteser härleds utifrån befintlig forskning och teori inom området för revisionsbyråbyten. Dessa prövas genom en kombinerad enkät- och dokumentstudie av totalt 100 bolag för perioden mellan 2010-2014. Resultat: Av studiens totalt 100 bolag visade det sig att 33 bolag (33 %) bytt revisionsbyrå under perioden mellan 2010-2014. 14 av studiens 15 hypoteser förkastas i hypotesprövningen. Kunskapsbidrag: I den statistiska analysen visas variablerna revisionskostnad, byte av ledning, bristfälligt samarbete och tredje parts påtryckningar bli signifikanta i att förklara ett byte av revisionsbyrå. Endast variabeln bristfälligt samarbete uppvisar dock ett korrekt förutspått samband, där ett ökat bristfälligt samarbete mellan revisor och bolagsledning ökar sannolikheten för ett byte av revisionsbyrå. / Problem: Increased concern regarding an enlarged competition and more frequent audit firm switching behavior has been noticed among the Big 4-audit firms. There is a need to explain why companies voluntarily choose to switch audit firm. Purpose: The aim of the study is to explain why companies voluntarily choose to switch audit firm. Method: 15 hypothesis are derived from existent research and theory in the area of audit firm switching. They are tested through a combined survey- and document study of 100 companies during the period of 2010-2014. Results: The study showed that 33 out of 100 companies (33 %) switched their audit firm during the period of 2010-2014. 14 out of 15 hypothesis are rejected in the study. Contribution: The statistical analysis showed that the variables audit fee, change in management, inadequate working relationship and third party influences are significant in explaining an audit firm switch. However, the only variable to show a correctly predicted relationship is inadequate working relationship, which implicates that an increased inadequate working relationship between the auditor and management leads to an increased probability of an audit firm switch.

Recent evidence suggests that when performing reach-and-grasp actions on day-to-day objects, lift-actions are faster to execute relative to use-actions, and that a “use-on-lift” interference occurs and produces switch costs when changing actions from using to then lifting (Jax & Buxbaum, 2010; Osiurak & Badets, 2016). Such findings result from paradigms that include the sudden appearance of objects, requiring participants to react quickly to the features of the object, independent of the functionality of the objects. Because of the importance this topic has to day-to-day interactions with objects, the following four experiments were executed with objects continuously visible to participants. When imitating images of hand actions on objects, participants showed no differences in the initiation time of use- and lift-actions, suggesting that no systematic differences exist between these two actions. Using this as a baseline, we compared a more generative approach, as when actions are instructed by auditory sentences. In this case, we see that switching actions is difficult, switching objects is even more difficult, and that use-actions are modestly faster than lift-actions; the reverse of what previous research shows. In a third experiment modelled after the paradigm used in studies producing rapid lift- and slowed use-actions, we showed that use-actions are actually facilitating lift-actions. Further, we demonstrate that having a use-action goal in mind provides the knowledge required to perform a lift-action, and that use-actions are again faster than lift-actions. These results are a critical addition to the task-switching literature on the cognitive control of motor processes associated with hand actions as distinctions are made between non-naturalistic and realistic settings relevant to day-to-day interactions with objects. We show that use-actions facilitate lift-actions and that, in realistic settings, both use- and lift-actions require access to stored knowledge. / Graduate / 0633 / hvanmook@uvic.ca

Since the discovery of conducting polymers three decades ago the field of organic electronics has evolved rapidly. Organic light emitting diodes have already reached the consumer market, while organic solar cells and transistors are rapidly maturing. One of the great benefits with this class of materials is that they can be processed from solution. This enables several very cheap production methods, such as printing and spin coating, and opens up the possibility to use unconventional substrates, such as flexible plastic foils and paper. Another great benefit is the possibility of tailoring the molecules through carefully controlled synthesis, resulting in a multitude of different functionalities. This thesis reports how charge transport can be altered in solid-state organic electronic devices, with specific focus on memory applications. The first six chapters give a brief review of the field of solid-state organic electronics, with focus on electronic properties, resistance switch mechanisms and systems. Paper 1 and 3 treat Rose Bengal switch devices in detail – how to improve these devices for use in cross-point arrays as well as the origin of the switch effect. Paper 2 investigates how the work function of a conducting polymer can be modified to allow for better electron injection into an organic light emitting diode. The aim of the work in papers 4 and 5 is to understand the behavior of switchable charge trap devices based on blends of photochromic molecules and organic semiconductors. With this in mind, charge transport in the presence of traps is investigated in paper 4 and photochromic molecules is investigated using quantum chemical methods in paper 5. / Elektroniska komponenter har traditionellt sett tillverkats av kisel ellerandra liknande inorganiska material. Denna teknologi har förfinats intillperfektion sedan mitten av 1900-talet och idag har kiselkretsar mycket högprestanda. Tillverkningen av dessas kretsar är dock komplicerad och är därförkostsam. Under 1970-talet upptäcktes att organiska polymerer (dvs plast) kanleda ström under vissa förutsättningar. Genom att välja lämplig polymer ochbehandla den med vissa kemikalier (så kallad dopning) kan man varieraledningsförmågan från isolerande till nästintill metallisk. Det öppnarmöjligheten för att skapa elektroniska komponenter där dessa organiskamaterial utgör den aktiva delen istället för kisel. En av de stora fördelarna medorganiska material är att de vanligtvis är lösliga i vanliga lösningsmedel. Det göratt komponenter kan tillverkas mycket enkelt och billigt genom att användakonventionell tryckteknik, där bläcket har ersatts med lösningen av detorganiska materialet. Det gör också att komponenterna kan tillverkas påokonventionella ytor såsom papper, plast eller textil. En annan spännandemöjlighet med organiska material är att dess funktioner kan skräddarsys genomvälkontrollerad kemisk syntes på molekylär nivå. Inom forskningsområdetOrganisk Elektronik studerar man de elektroniska egenskaperna i de organiskamaterialen och hur man kan använda dessa material i elektroniskakomponenter. Vi omges idag av apparater och applikationer som kräver att data sparas,som till exempel digitala kameror, datorer och mobiltelefoner. Eftersom det finnsett stort intresse från konsumenter för nya smarta produkter ökar behovet avmobila lagringsmedia med stor lagringskapacitet i rasande fart. Detta harsporrat en intensiv utveckling av större och billigare fickminnen, hårddiskar ochminneskort. Många olika typer av minneskomponenter baserade på organiskamaterial har föreslagits de senaste åren. I vissa fall har dessa påståtts kunna erbjuda både billigare och större minnen än vad dagens kiselteknologi tillåter.En typ av organiska elektroniska minnen baseras på en reversibel ochkontrollerbar förändring av ledningsförmågan i komponenten. En informationsenhet – en så kallad bit – kan då lagras genom att till exempel koda en högledningsförmåga som en ”1” och en låg ledningsförmåga som en ”0”. Den härdoktorsavhandlingen är ett försök till att öka förståelsen för sådanaminneskomponenter. Minneskomponenter bestående av det organiska materialet Rose Bengalmellan metallelektroder har undersökts. Egenskaper för system bestående avmånga sådana komponenter har beräknats. Vidare visas att minnesfenomenetinte härstammar i det organiska materialet utan i metallelektroderna.Tillsammans med studier av andra forskargrupper har det här resultatetbidragit till en debatt om huruvida minnesmekanismerna i andra typer avkomponenter verkligen beror på det organiska materialet.Olika sätt att ändra transporten av laddningar i organiska elektroniskasystem har undersökts. Det visas experimentellt hur överföringen av laddningarmellan metallelektroder och det organiska materialet kan förbättras genom attmodifiera metallelektroderna på molekylär nivå. Vidare har det studeratsteoretiskt hur laddningar kan fastna (så kallad trapping) i organiska materialoch därmed påverka ledningsförmågan i materialet.En speciell typ av organiska molekyler ändrar sin struktur, och därmedegenskaper, reversibelt när de belyses av ljus av en viss våglängd, så kalladefotokroma molekyler. Denna förändring kan användas till att ändraledningsförmågan genom en komponent och därmed skulle man kunna användamolekylerna i en minneskomponent. I den sista delen av avhandlingen användskvantkemiska metoder för att beräkna egenskaperna hos dessa molekyler för attöka förståelsen för hur de kan användas i minneskomponenter.