published_or_final_version / Civil Engineering / Master / Master of Philosophy

Not available / text

Syfte: Syftet var att undersöka om det fanns någon skillnad i läshastighet med hjälp utav ett färgat filter (overlay) framför en text. Det undersöktes också om det var någon skillnad i ändringen av läshastighet mellan två olika åldersgrupper, en där deltagarna var över 18 år och en grupp där deltagarna var under 18 år gamla. Metod: Studien bestod av ett antal kliniska tester, klarade deltagarna normalvärdena för dessa tester fick de läsa ett lästest i en minut där antalet ord istället räknades och antecknades. Ett overlay valdes sedan och deltagaren läste då ett andra test i en minut där det också räknades ord och antecknades för att se om det fanns någon skillnad mellan läsningarna. Färgen och vilken sida på overlayet som valdes antecknades. Resultat: En signifikant skillnad mellan att läsa med och utan overlay fanns (p < 0,001). I de båda åldersgrupperna skedde en ökning av läshastighastigheten med hjälp utav ett overlay. Ökningen i den yngre åldersgruppen var 7,3 % med hjälp av overlay och i gruppen där deltagarna var över 18 år var förbättringen 6,1 %. I de båda grupperna fanns det också ett fåtal deltagare som läste saktare med overlay. Slutsats: Överlag visar detta att overlays kan hjälpa till att öka läshastigheten både hos barn och vuxna. Valet av färg på overlays skiljde sig åt mellan grupperna. / The aim of this study was to investigate if there was any difference in the reading speed with a coloured overlay when it was used on top of the text of a newly developed swedish reading test. The study also investigated if there were any differences in the change of reading speed between two different age groups. The study consisted of a number of clinical tests, the tests were visual aquity assessment for near and distance, colour vision and stereopsis. If the participants managed the normal values for these tests they were allowed to read a swedish reading test out loud three times for one minute each. The first time was for learning the structure of the reading test, the second time was read without overlay and the third time was read with an overlay. In the last two times the number of words were counted and noted. There was a significant difference in the reading speed with and without overlay (p < 0.001). In both the age groups there was an increase in reading speed when the overlay was used. The increase was 7.3 % with overlay in the younger age group and in the group where the participants were over 18 years old, the increase was 6.1 %. In both of the groups there was a small number of people whose reading speed was reduced when using an overlay. Overall this study shows that overlays can increase the reading speed in both children and adults. The chosen colour on the overlay differed between the two groups.

published_or_final_version / Management Studies / Master / Master of Philosophy

In this dissertation we consider several limiting criteria forn-dimensional diffusion processes defined as solutions of stochasticdifferential equations. Our main interest is in criteria for polynomialand exponential rates of convergence to the steady state distributionin the total variation norm. Resulting criteria should place assumptionsonly on the coefficients of the elliptic differentialoperator governing the diffusion.Coupling of Harris chains is one of the main methods employed in thisdissertation.

One of the most important aspects of coastal management and planning programs that needs to be investigated is shoreline dynamics. Long-term coastal analysis uses historical data to identify the sectors along the coast where the shoreline position has changed. Among the information that can be obtained from these studies are the general trend of coasts, either advancing or retreating. The erosion or accretion rates at each location can be used to forecast future shoreline positions. The current techniques used to study shoreline evolution are generally based on transects perpendicular to a baseline at selected points. But these techniques proved to be less efficient along more complex shorelines, and need to be refined. A new and more reliable method, the topologically constrained transect method (TCTM), was developed for this study and tested using data available for three sectors of the Texas Gulf Coast. Output data generated from TCTM also allowed performing shoreline evolution analysis and forecasting based on historical positions. Using topological constrained transects, this study provides a new method to estimate total areas of accretion or erosion at each segment of the coastline. Reliable estimates of future gains or losses of land along the coast will be extremely useful for planning and management decisions, especially those related to infrastructure and environmental impacts, and in the development of coastal models. Especially important is the potential to quickly identify areas of significant change, which eliminates the need for preliminary random sample surveying, and concentrate higher-resolution analyses in the most significant places. The results obtained in this research using the new methodology show that the Texas coast generally experiences erosion, with anthropogenic factors responsible for accretion. Accretion areas are located near coastal infrastructure, especially jetties that block the along shore sediment transport. The maximum erosion rate obtained in the study area is 5.48 m/year. This value helps make us aware of the powerful dynamic of the sector.

Sex-specific calls are used in male-male agonistic encounters and male-female courtship in many animal species. The ring-tailed lemur (Lemur catta) is a gregarious Malagasy strepsirhine with twenty-two distinct vocalizations for adults, including two male-specific vocalizations and an additional vocalization with male-specific functions: the howl, the squeal, and the purr. Proposed intra-sexual agonistic functions for these three vocalizations have never been empirically tested. This study’s purpose was to investigate the functions of howling, squealing, and purring in the ring-tailed lemur, and to assess the relationships between the rates of these vocalizations and male dominance. From March to July 2010, I collected 600 hours of total data and 480 hours of focal data on male ring-tailed lemurs aged three and older at Beza Mahafaly Special Reserve, Madagascar. I observed each male continuously for 30 minutes at a time and noted behaviours including all vocalizations and all agonism using one–zero sampling at 2.5-min intervals. I calculated male dominance rank and vocalization rates from these data. My results indicated that male dominance rank is correlated with male purring rate and with squealing rate, but not with howling rate. Male purring rate increased during intra-sexual agonism and was associated with aggression in agonistic encounters. Squealing rate increased during male-male agonism and indicated both aggression and submission in male-male encounters. Howling rate increased during inter-group encounters and a greater number of males participated in multi-male howling choruses when non-group members were present. Purring and squealing are agonistic vocalizations and used in male-male agonism in the ring-tailed lemur, while howling is used in inter-group encounters.

Sex-specific calls are used in male-male agonistic encounters and male-female courtship in many animal species. The ring-tailed lemur (Lemur catta) is a gregarious Malagasy strepsirhine with twenty-two distinct vocalizations for adults, including two male-specific vocalizations and an additional vocalization with male-specific functions: the howl, the squeal, and the purr. Proposed intra-sexual agonistic functions for these three vocalizations have never been empirically tested. This study’s purpose was to investigate the functions of howling, squealing, and purring in the ring-tailed lemur, and to assess the relationships between the rates of these vocalizations and male dominance. From March to July 2010, I collected 600 hours of total data and 480 hours of focal data on male ring-tailed lemurs aged three and older at Beza Mahafaly Special Reserve, Madagascar. I observed each male continuously for 30 minutes at a time and noted behaviours including all vocalizations and all agonism using one–zero sampling at 2.5-min intervals. I calculated male dominance rank and vocalization rates from these data. My results indicated that male dominance rank is correlated with male purring rate and with squealing rate, but not with howling rate. Male purring rate increased during intra-sexual agonism and was associated with aggression in agonistic encounters. Squealing rate increased during male-male agonism and indicated both aggression and submission in male-male encounters. Howling rate increased during inter-group encounters and a greater number of males participated in multi-male howling choruses when non-group members were present. Purring and squealing are agonistic vocalizations and used in male-male agonism in the ring-tailed lemur, while howling is used in inter-group encounters.

The incidence of restenosis has been shown to be correlated with the overstretching of the arterial wall during an angioplasty procedure. It has been proposed that slow balloon inflation results in lower intramural stresses, therefore minimizing vascular injury and restenosis rate. The analysis of the biomechanics of the arterial tissue might contribute to understand which factors trigger restenosis. However, few mechanical data are available on human arteries because of the difficulty of testing artery samples often obtained from autopsy while arteries are still considered "fresh". Various solutions mimicking the physiological environment have been used to preserve artery samples from harvesting to testing. In vitro mechanical testing is usually preferred since it is difficult to test arteries in vivo. Uniaxial and biaxial testing has been used to characterize anisotropic materials such as arteries, although methodological aspects are still debated. Several objectives were formulated and analyzed during the making of this thesis. In one study, the effect of deformation rate on the mechanical behavior of arterial tissue was investigated. The effect of several preservation methods, including cryopreservation, on the mechanical properties of porcine thoracic aortas was also analyzed. Finally, the differences in the mechanical behavior between three different types of sample geometry and boundary conditions were compared under uniaxial and equi-biaxial testing. Thoracic aortas were harvested within the day of death of pigs from a local slaughterhouse. Upon arrival, connective tissue was removed from the external wall of the artery. Then the artery was cut open along its length and cut out in rectangular samples for uniaxial testing, and square and cruciform samples for biaxial testing. Samples belonging to the freezing effect study were preserved for two months at -20°C and -80°C in isotonic saline solution, Krebs-Henseleit solution with 1.8 M dimethylsulfoxide, and dipped in liquid nitrogen. Samples belonging to the deformation rate effect study were tested uniaxially and equi-biaxially at deformation rates from 10 to 200 %/s. The uniaxial and biaxial experiments were simulated with the help of an inverse finite element software. The use of inverse modeling to fit the material properties by taking into account the non-uniform stress distribution was demonstrated. A rate-dependent isotropic hyperelastic constitutive equation, derived from the Mooney-Rivlin model, was fitted to the experimental results (i.e. deformation rate study). In the proposed model, one of the material parameters is a linear function of the deformation rate. Overall, inverse finite element simulations using the proposed constitutive relation accurately predict the mechanical properties of the arterial wall. In this thesis, it was found that easier attachment of samples (rectangular and cruciform) is accomplished using clamps rather than hooks. It was also found that the elastic behavior of arteries is nonlinear and non-isotropic when subjected to large deformations. Characterization of the arterial behavior at large deformations over a higherdeformation range was achieved using cruciform samples. The mechanical properties of arteries did not significantly change after preservation of arteries for two months. Under uniaxial and biaxial testing, loading forces were reduced up to 20% when the deformation rate was increased from 10 to 200 %/s, which is the opposite to the behaviour seen in other biological tissues. The differences observed in the mechanical behavior of fresh and thawed samples were not significant, independently of the storing medium or freezing temperature used. The lack of significant differences observed in the freezing study was likely due to the small number of samples tested per storing group. Further studies are required to clarify the impact of cryopreservation on extracellular matrix architecture to help tailor an optimized approach to preserve the mechanical properties of arteries. From the results obtained in the deformation rate study, it is concluded that the stiffness of arteries decreases with an increase in the deformation rate. In addition, the effect of deformation rate was observed to be higher than the effect of anisotropy. The inverse relationship between stiffness and deformation rate raises doubts on the hypothesized relationship between intramural stress, arterial injury, and restenosis.

The aim of the study: to identify the effect of pedaling rate of cyclists to the indices of vegetative systems during consistently increasing workload. Hypothesis. We claimed that the rate of pedaling will have impact on some indices of cyclists’ vegetative systems during consistently increasing workload. The objectives 1. To evaluate the effect of pedaling rate to indices of maximal aerobic power. 2. To evaluate the effect of pedaling rate to indices of anaerobic metabolism threshold. 3. To identify the effect of pedaling rate to the efficiency of aerobic work. Subjects: 7 Lithuanian cyclists – the members of the selected. Their age: 18,1±2,04 years, height: 178±6,4 cm, and body mass 71,6±8,4 kg. The methods of the study: 1) the identification of aerobic fitness during the consistently increasing workload on the veloergometer with different pedaling rates (70, 90, 110 rpm). The warming-up was performed (10 min with the 50 W power). The initial testing load (20 W) was increased every 5 s, consistently by 2 W. The load was increased until the fatigue. After that the subject rested in lying position for 5 minutes. The workload was applied once a day; 3 tests were conducted during a week. 2) The first (VeT1) and the second (VeT2) ventilatory thresholds were determined according to the dependence of lungs ventilation and also of ventilatory oxygen and CO2 equivalents on the power of the work. After 5 minutes of the rest period the capillary blood samples were taken from the... [to full text]