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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
171

Assessing locomotion in cats trained on a flat treadmill and on a ladder treadmill before and after spinal cord injury (SCI)

Escalona Castillo, Manuel Jose 09 1900 (has links)
Les effets des lésions de la moelle épinière sur la locomotion sont souvent évalués sur un tapis roulant avec une surface plane, ce qui demande peu d’implication active des structures supraspinales. L’objectif du présent travail est d’évaluer si un type d’entraînement nécessitant une plus grande part de contrôle volontaire (c.-à-d. supraspinal) pourrait améliorer la récupération de la marche chez le chat après une hémilésion unilatérale spinale au niveau thoracique (T10). Pour ce faire, pendant 6 semaines les chats ont été entrainés sur un tapis roulant conventionnel ou sur un tapis-échelle roulante, tâche requérant un placement des pattes plus précis. Les paramètres de la marche ont été évalués par cinématique et électromyographie (EMG) avant et une fois par semaine pendant 6 semaines après lésion. Nos résultats comparant la marche sur tapis conventionnel à celle sur échelle roulante montrent des différences dans les excursions angulaires et les couplages entre les membres. On observe aussi des différences dans l’amplitude des EMG notamment une augmentation de la deuxième bouffée du muscle Semitendineux (St) sur l’échelle roulante. Après l’hémilésion spinale cette bouffée disparait du côté de la lésion tandis qu’elle est maintenue du côté intact. Après l’entrainement sur échelle roulante, on observe des changements de trajectoire de la patte et une disparition du pied tombant (foot drag) qui suggèrent une amélioration du contrôle de la musculature distale. Nos résultats montrent que le patron locomoteur observé sur tapis conventionnel est influencé par le type d’entraînement procuré. De plus, certains paramètres de la locomotion suggèrent que l’entraînement sur échelle roulante, qui requiert plus de contrôle supraspinal, favorise une meilleure récupération de la marche après lésion spinale. / The effects of spinal cord lesions on locomotion in animals is often assessed on a flat surface which requires minimal supraspinal demands. Here we investigated whether locomotor training requiring more voluntary commands could improve recovery in cats after a unilateral hemisection on the left side (Thoracic 10). Cats were trained for 6 weeks on a conventional flat treadmill (FTM) or on a ‘ladder treadmill’ (LTM) requiring precise foot positioning. Locomotor parameters such as kinematics and electromyographic activity (EMG) were evaluated before and once a week for 6 weeks after spinal hemisection. There were differences in angular excursions and limb couplings when comparing walking on FTM and LTM and important changes occurred in the amplitude of EMGs such as an increased second burst in Semitendinosus (St) during LTM stepping. After the left hemisection, this burst disappeared on the left side while it was maintained on the right (non lesioned) side. With LTM training, we observed changes in limb trajectories and disappearance of foot drag of the left foot during FTM stepping suggesting a better control of distal musculature. Our results show that locomotor patterns observed during FTM stepping are influenced by different training modalities and also that training on the LTM after a spinal hemisection, demanding more supraspinal control, leads to a better stepping pattern.
172

High-field electron spin resonance in low-dimensional spin systems

Ozerov, Mykhaylo 04 May 2011 (has links)
Due to recent progress in theory and the growing number of physical realizations, low-dimensional quantum magnets continue to receive a considerable amount of attention. They serve as model systems for investigating numerous physical phenomena in spin systems with cooperative ground states, including the field-induced evolution of the ground-state properties and the corresponding rearrangement of their low-energy excitation spectra. This work is devoted to systematic studies of recently synthesized low-dimensional quantum spin systems by means of multi-frequency high-field electron spin resonance (ESR) investigations. In the spin- 1/2 chain compound (C6H9N2)CuCl3 [known as (6MAP)CuCl3] the striking incompatibility with a simple uniform S = 1/2 Heisenberg chain model employed previously is revealed. The observed ESR mode is explained in terms of a recently developed theory, revealing the important role of the alternation and next-nearest-neighbor interactions in this compound. The excitations spectrum in copper pyrimidine dinitrate [PM·Cu(NO3)2(H2O)2]n, an S = 1/2 antiferromagnetic chain material with alternating g-tensor and Dzyaloshinskii-Moriya interaction, is probed in magnetic fields up to 63 T. To study the high field behavior of the field-induced energy gap in this material, a multi-frequency pulsed-field ESR spectrometer is built. Pronounced changes in the frequency-field dependence of the magnetic excitations are observed in the vicinity of the saturation field, B ∼ Bs = 48.5 T. ESR results clearly indicate a transition from the soliton-breather to a spin-polarized state with magnons as elementary excitations. Experimental data are compared with results of density matrix renormalization group calculations; excellent agreement is found. ESR studies of the spin-ladder material (C5H12N)2CuBr4 (known as BPCB) completes the determination of the full spin Hamiltonian of this compound. ESR results provide a direct evidence for a pronounced anisotropy in this compound, that is in contrast to fully isotropic spin-ladder model employed previously for BPCB. Our observations can be of particular importance for describing the rich temperature-field phase diagram of this material. The frequency-field diagram of magnetic excitations in the quasi-two dimensional S = 1/2 compound [Cu(C4H4N2)2(HF2)]PF6 in the AFM-ordered state is studied. The AFM gap is observed directly. Using high-field magnetization and ESR results, parameters of the effective spin-Hamiltonian (exchange interaction, anisotropy and g-factor) are obtained and compared with those estimated from thermodynamic properties of this compound.
173

A global pandemic’s influence on consumer behaviour : A quantitative study on how the social constraints due to COVID-19 has affected the engagement in post-purchase behaviour

Damsjö, Evelina, Mattsson, Fanni, Olsson, Amanda January 2021 (has links)
Since the COVID-19 outbreak, countless studies have been conducted about the pandemic regarding people's physical and mental health, but there is a significant gap on the persistent effects on consumer behaviour. Hence, this thesis aimed to investigate if there is a relationship between the social constraints as a consequence of the COVID-19 pandemic and the potential increased engagement of post-purchase behaviour. The research focused exclusively on Swedish female millennials who are active social media users.    The research used a deductive approach by formulating hypotheses based on already existing theories. The explanatory design was used when aiming to investigate a causal relationship between two variables, i.e., prior to the pandemic compared to today. Further, a quantitative strategy was used by collecting primary data through a questionnaire, which thereafter was analysed through SPSS, using the paired sample t-test. To target the desired sample a convenience sampling method was used which collected a total of 226 respondents, with 197 valid participants. The sample was collected through several Facebook groups, combined with the utilizing of the authors own social media channels. Since this study aimed to measure engagement, the key concepts were converted in the survey questions to more specific terms, by a modified existing scale. Indicators were established to be able to measure the engagement under controlled conditions.   Furthermore, the results from the statistical tests resulted in a p-value to confirm or reject the null hypothesis, followed by a correlation coefficient value to determine the strength of the relationship. The empirical findings combined indicated significant evidence that because of the social constraints since the COVID-19 outbreak, there has been an increased engagement in the post-purchase behaviour on social media for Swedish female millennials. This was confirmed through a p-value of 0.000 in the t-tests for all seven hypotheses. Furthermore, all tests show correlation values between 0.449 and 0.617, which means that all the existing relationships are positive.    This means that during the period when COVID-19 has been an active societal problem with all its effects, the new living conditions have entailed an increased involvement in post-purchase behaviour on social media for Swedish female millennials. If corporations take these changed behaviours in consideration and adapt the marketing strategy accordingly, it  can contribute to increased sales as the credibility of the brand gets strengthened through the transparency that the customer base values.
174

Mécanique quantique supersymétrique et opérateurs d’échelle pour le système de Rosen-Morse

Garneau-Desroches, Simon 07 1900 (has links)
Le présent mémoire est dédié à l’étude du rôle de la mécanique quantique supersymétrique dans la construction d’opérateurs d’échelle et de leurs applications pour le système quantique de Rosen-Morse. L’aboutissement de ces travaux est contenu dans un article qui constitue le dernier chapitre du mémoire. Précisément, on motive l’échec de la réalisation des opérateurs d’échelle comme opérateurs différentiels pour le potentiel de Rosen-Morse avec les méthodes traditionnelles. On exploite la propriété d’invariance de forme dans le contexte de la mécanique quantique supersymétrique comme un outil alternatif pour offrir une première approche quantique à la réalisation des opérateurs d’échelle pour la version hyperbolique de ce potentiel. On utilise cette réalisation pour obtenir celle d’opérateurs d’échelle pour une classe particulière d’extensions rationnelles du potentiel de Rosen-Morse hyperbolique avec des techniques issues de la supersymétrie. Des états cohérents sont construits à partir des réalisations obtenues pour les différents systèmes. Certaines de leurs propriétés sont analysées et mises en comparaison. En parallèle, on utilise une transformation canonique ponctuelle pour déduire une première réalisation des opérateurs d’échelle comme opérateurs différentiels pour le système de Rosen-Morse trigonométrique. De cette réalisation sont construits des états cohérents pour lesquels des propriétés sont similairement analysées. / This master thesis is dedicated to the study of the role of supersymmetric quantum mechanics in the construction of ladder operators and of their applications for the quantum Rosen-Morse system. The results of this work are presented in an article that constitutes the last chapter of the thesis. Precisely, we motivate the failure of traditional methods in providing a realization for the Rosen-Morse ladder operators as differential operators. We provide a first quantum-based solution to this problem by using the shape invariance property in supersymmetric quantum mechanics as a tool in the construction of the ladder operators for the hyperbolic version of this potential. We use the latter realization to obtain that of a specific class of rational extensions of the hyperbolic Rosen-Morse system by means of supersymmetric techniques. Coherent states are constructed from the ladder operators obtained for the different systems. Some properties are analyzed and compared. In addition, we make use of a point canonical transformation in the derivation of the first realization of the ladder operators of the trigonometric Rosen-Morse system as differential operators. From this realization, we construct coherent states for which some properties are similarly analyzed.
175

Enzyme selectivity as a tool in analytical chemistry

Hamberg, Anders January 2007 (has links)
Enzymes are useful tools as specific analytical reagents. Two different analysis methods were developed for use in the separate fields of protein science and organic synthesis. Both methods rely on the substrate specificity of enzymes. Enzyme catalysis and substrate specificity is described and put in context with each of the two developed methods. In paper I a method for C-terminal peptide sequencing was developed based on conventional Carboxypeptidase Y digestion combined with matrix assisted laser desorption/ionization mass spectrometry. An alternative nucleophile was used to obtain a stable peptide ladder and improve sequence coverage. In paper II and III, three different enzymes were used for rapid analysis of enantiomeric excess and conversion of O-acylated cyanohydrins synthesized by a defined protocol. Horse liver alcohol dehydrogenase, Candida antarctica lipase B and pig liver esterase were sequentially added to a solution containing the O-acylated cyanohydrin. Each enzyme caused a drop in absorbance from oxidation of NADH to NAD+. The conversion and enantiomeric excess of the sample could be calculated from the relative differences in absorbance. / QC 20101108
176

Convolutional neural network based object detection in a fish ladder : Positional and class imbalance problems using YOLOv3 / Objektdetektering i en fisktrappa baserat på convolutional neural networks : Positionell och kategorisk obalans vid användning av YOLOv3

Ekman, Patrik January 2021 (has links)
Hydropower plants create blockages in fish migration routes. Fish ladders can serve as alternative routes but are complex to install and follow up to help adapt and develop them further. In this study, computer vision tools are considered in this regard. More specifically, object detection is applied to images collected in a hydropower plant fish ladder to localise and classify wild, farmed and unknown fish labelled according to the presence, absence or uncertainty of an adipose fin. Fish migration patterns are not deterministic, making it a challenge to collect representative and balanced data to train a model that is resilient to changing conditions. In this study, two data imbalances are addressed by modifying a YOLOv3 baseline model: foreground-foreground class imbalance is targeted using hard and soft resampling and positional imbalance using translation augmentation. YOLOv3 is a convolutional neural network predicting bounding box coordinates, class probabilities and confidence scores simultaneously. It divides images into grids and makes predictions based on grid cell locations and anchor box offsets. Performance is estimated across 10 random data splits and different bounding box overlap thresholds, using (mean) average precision as well as recall, precision and F1 score estimated at optimal validation set confidence thresholds. The Wilcoxon signed-ranks test is used for determining statistical significance. In experiments, the best performance was observed on wild and farmed fish, with F1 scores reaching 94.8 and 89.0 percent respectively. The inconsistent appearance of unknown fish appears harder to generalise to, with a corresponding F1 score of 65.7 percent. Soft sampling but especially translation augmentation contributed to enhanced performance and reduced variance, implying that the baseline model is particularly sensitive to positional imbalance. Spatial dependencies introduced by YOLOv3’s grid cell strategy likely produce local bias or overfitting. An experimental evaluation highlight the importance of not relying on a single data split when evaluating performance on a moderately large or custom dataset. A key challenge observed in experiments is the choice of a suitable confidence threshold, influencing the dynamics of the results. / Vattenkraftverk blockerar fiskars vandringsvägar. Fisktrappor kan skapa alternativa vägar men är komplexa att installera och följa upp för vidare anpassning och utveckling. I denna studie betraktas datorseende i detta avseende. Mer specifikt appliceras objektdetektering på bilder samlade i en fisktrappa i anslutning till ett vattenkraftverk, med målet att lokalisera och klassificera vilda, odlade och okända fiskar baserat på förekomsten, avsaknaden eller osäkerheten av en fett-fena. Fiskars migrationsmönster är inte deterministiska vilket gör det svårt att samla representativ och balanserad data för att trana en modell som kan hantera förändrade förutsättningar. I denna studie addresseras två obalanser i datan genom modifikation av en YOLOv3 baslinjemodell: klass-obalans genom hård och mjuk återanvändning av data och positionell obalans genom translation av bilder innan träning. YOLOv3 är ett convolutional neural network som simultant förutsäger avgränsnings-lådor, klass-sannolikheter och prediktions-säkerhet. Bilder delas upp i rutnätceller och prediktioner görs baserat på cellers position samt modifikation av fördefinierade avgränsningslådor. Resultat beräknas på 10 slumpmässiga uppdelningar av datan och för olika tröskelvärden för avgränsningslådors överlappning. På detta beräknas (mean) average precision, liksom recall, precision och F1 score med tröskelvärden för prediktions-säkerhet beräknat på valideringsdata. Wilcoxon signed-ranks test används för att avgöra statistisk signifikans. Bäst resultat observeras på vilda och odlade fiskar, med F1 scores som når 94.8 respektive 89.0 procent. Okända fiskars inkonsekventa utseenden verkar svårare att generalisera till, med en motsvarande F1 score på 65.7 procent. Mjuk återanvändning av data men speciellt translation bidrar till förbättrad prestanda och minskad varians, vilket pekar på att baslinjemodellen är särskilt känslig för positionell obalans. Spatiala beroenden skapade av YOLOv3s rutnäts-strategi producerar troligen lokal partiskhet eller överträning. I en experimentell utvärdering understryks vikten av multipel uppdelning av datan vid evaluering på ett måttligt stort eller egenskapat dataset. Att välja tröskelvärdet för prediktions-säkerhet anses utmanande och påverkar resultatens dynamik.
177

Developing A Translator Career Path: a New Approach to In-House Translator Development Evaluation

Alowedi, Noha 01 December 2015 (has links)
No description available.
178

Sustainable Food Systems : Leveraging Producer-Retailer Relationships

Adolfsson, Olivia January 2024 (has links)
Abstract: An unsustainable food system in Sweden, marked by power imbalances, limited opportunities for smaller producers, and a lack of collaboration, demands solutions. Many workers in the food system operate as smaller producers, while the retail sector is highly concentrated, dominated by a few major retailers. Due to their significant market share, these retailers have the potential to drive production improvements, sustainability, and innovation by actively supporting smaller producers. However, if these issues remain unaddressed, the entire food system risks becoming increasingly vulnerable to future disruptions. This thesis aims to explain the dynamics within the Swedish food value chain, focusing on the collaboration between established retailers and smaller producers. It seeks to understand how this collaboration can be improved by both parties to foster a more sustainable food system. Through qualitative semi-structured interviews employing a dual-perspective approach from both producers and retailers, it sought an understanding of both actors’ perspectives regarding their current experiences and perceptions. Both producers and retailers acknowledge the need for collaboration, but challenges persist, particularly expressed by the producers. The main theory used, The Ladder of Partnership, highlights the necessity for trust, mutual understanding, and investment in collaboration. While some companies are making efforts, more is required for a sustainable food system. Given the retailer’s market influence, they should lead by creating opportunities for smaller producers, making strategic decisions about market inclusion, and excluding less sustainable options. The thesis advocates for accountability and shared responsibility among all actors in the food system to achieve a sustainable future. The study concludes that the Swedish food value chain relies on collaboration among various actors, and without it, the system's functionality would be compromised. / Summary: Walking into a vibrant supermarket opens up a world of diverse choices, showcasing both local and global products and turning grocery shopping into a journey through the interconnected global food system. Each item on the shelf tells a story of its own, a journey from farm to fork. Just as each product on the shelf tells a story, so too does our collective effort to foster a more sustainable future. From supporting smaller producers to advocating for environmental sustainability, every decision we make has an impact, leading to the outcome dependent on our action.  This thesis aims to explain the dynamics within the Swedish food value chain, focusing on the collaboration between established retailers and smaller producers. It seeks to understand how this collaboration could be improved by both retailers and producers regarding the essential support required for fostering a more sustainable food system. Through qualitative semi-structured interviews, this study was focusing on the relationships between producers and retailers, and it sought an understanding of both actors’ perspectives regarding their current experiences and perceptions.  In Sweden, a select few major players are dominating a significant portion of the market share. An unsustainable food system in Sweden, marked by power imbalances, limited opportunities for smaller producers and a lack of collaboration, demands solutions. The entire food system risks becoming increasingly vulnerable to future disruptions if these issues remain unaddressed. The findings reveal a complex network of interconnected factors and actors. Companies operate not only as one actor, but very often as several (e.g. producers, distributor, consumers) influencing the functioning of the entire chain. In essence, the collaboration between retailers and smaller producers in the Swedish food system presents a dynamic interplay of challenges and opportunities. While both parties acknowledge the importance of working together, there are still challenges to overcome, especially from the producers' perspective of working together with retailers.   The main theory used, The Ladder of Partnership, highlights the necessity for trust, mutual understanding, and investment in collaboration. While some companies are making efforts, more is required for a sustainable food system. Given the retailer’s market influence, they should lead by creating opportunities for smaller producers, making strategic decisions about market inclusion, and excluding less sustainable options. The thesis advocates for accountability and shared responsibility among all actors in the food system to achieve a sustainable future. The study concludes that the Swedish food value chain relies on collaboration among various actors, and without it, the system's functionality would be compromised.
179

Invånarinvolvering som demokratiskt uttryck vid gestaltning av offentlig livsmiljö : En fallstudie av Helsingborgs stads projekt “Nytt stadsbibliotek” / Citizen involvement as a democratic expression in the design of public environments : A case study of Helsingborgs stad project “Nytt stadsbibliotek”

Hejdström, Fanny, Hansson, Gemila January 2024 (has links)
Dagens befolkning ställs inför många utmaningar där vikten av social hållbarhet har blivit framträdande som en av många nycklar för fungerande samhällen. Ekologisk och ekonomisk hållbarhet tillåter i många avseenden mer mätbarhet. Trots detta är social hållbarhet minst lika viktigt. Vikten av att involvera invånare och demokrati är väsentliga delar för att kunna arbeta för social hållbarhet. Följaktligen fokuserar följande diskurs på arbete och metoder kring invånarinvolvering i gestaltning av offentlig livsmiljö. Med anledning av bristen på tydliga riktlinjer samt för att förstå fördelarna med inkludering av invånare har denna uppsats formulerats. Vidare tar diskursen upp metoder och exempel från verkligheten för att vidareutveckla kompetensen och diskutera vikten av väl implementerade invånarinvolveringsprocesser vid stadsplanering och fysisk planering. Uppsatsen tar avstamp i Helsingborgs stads projekt Nytt stadsbibliotek för att undersöka involveringsmetoderna i samband med utvecklingen av stadens nya bibliotek. Vid gestaltning av arkitektur som ämnar vara en plats för befolkningen - vilka mandat får då invånarna att påverka? Denna abduktiva forskningsansats har skapats med kvalitativa metoder som tillvägagångssätt i egenskap att förstå för- och nackdelar vid involvering. Centralt för uppsatsen har intervjuer med representanter från Helsingborgs stad varit med syfte att fördjupa fallstudien samt diskutera invånarinvolvering som demokratiskt uttryck. Praktiska metoder i kombination med teori och uttalade riktlinjer lyfts upp för att analyseras samt öka kunskapen på ämnet. Trots att olika metoder av involvering inkluderar invånare i olika grader, konkluderar uppsatsen att den högsta graden av inkludering inte nödvändigtvis är den mest optimala. / The current population is faced with many challenges where the importance of social sustainability has become prominent as one of many keys to reach functioning societies. Ecological and economic sustainability are in some regard allowing for more measurability. Despite this, social sustainability is at least as important. The importance of involving citizen and democracy are essential parts of being able to work for social sustainability. Consequently, the following discourse focuses on work and methods around citizens involvement in the design of the public environment. Due to the lack of clear guidelines and in order to understand the benefits of inclusion of citizens this essay has been constructed. Furthermore, the discourse addresses methods and real-life examples to further develop the competence and discuss the importance of well-implemented citizen involvement processes in urban-and physical planning. This essay is based on Helsingborg’s project Nytt stadsbibliotek to investigate the involvement methods in connection with the development of the city’s new library. When designing architecture that aims to be a place for the citizens - what mandates do the residents get to influence? This abductive research approach has been designed with qualitative methods as a way to understand the pros and cons of involvement. Interviews with representatives from the city of Helsingborg have been crucial in the essay with the aim of deepening the case study and discussing citizen involvement as a democratic expression. Practical methods in combination with theory and declared guidelines are highlighted to be analyzed and to increase knowledge on the subject. Although different methods of involvement include citizens to different degrees, this paper concludes that the highest degree of inclusion is not necessarily the most optimal solution.
180

Adaptivní kmitočtový filtr / Adaptive frequency filter

Kříž, Petr January 2010 (has links)
The aim of this work is to design a filter of the type low–pass of order 5th with Butterworth’s approximation in the range of over-tuning 10 – 100 kHz and if it will be possible so! achieve even higher marginal frequencies. To compare two typical representatives of the frequency filters cascading and non-cascading synthesis from the viewpoint the accuracy of an! approximation function, sensitivity to the tolerance values of components, number of the components (mainly OZ) and viability, especially the possibility of electronic over-tuning in selected frequency range. On the basis of these conditions will be chosen one design, which will be realized later. Further it will be necessary to consider the possibilities of electronic over-tuning and to choose for this over-tuning suitable component, to design user management changes of marginal frequency fm by the help of keyboard + LCD and control application on the PC. For this hardware will be programmed appropriate control software. At the end of this work will be constructed appropriate device, which fullfils requirements written above and will be subjected to the laboratory measurements that verify function of this device. The constructional details of the filter are presented in the enclosure at the end of this work. At the CD are available all materials, which were created during the master’s thesis or which are necessarily concerned.

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