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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.
1

How does predation from fish influence the benthic invertebrates’ species composition in the Phragmites australis and Chara vegetation of Lake Takern?

Aigbavbiere, Ernest January 2011 (has links)
Predation is one of the important selective factors that regulate the species composition of benthic invertebrate communities. The study objective was to investigate the invertebrate distribution in two contrasting habitats in Lake Takern, southern Sweden, submerged Chara vegetation and emergent Phragmites australis vegetation, and to investigate the influence of predation from fish on certain invertebrates. Laboratory studies were used to estimate handling time and the intake rate (mg/sec) by the fish based on the optimal foraging model. In the field, fish and invertebrates were collected with gill nets and hand nets respectively and the fish gut content was analyzed. In total, sixteen invertebrates’ taxa were collected from the two habitats. The proportion of the invertebrate’s overlaps from each of the habitat was calculated by Renkonen index and with Sorensen diversity index. Both indices showed a similarity larger than 65%, indicating that there was no significant difference in the invertebrates’ distribution in the P. australis and the Chara habitat. The fish caught with the gill nets were: roach (Rutilus rutilus), perch (Perca fluviatilis), tench (Tinca tinca), and rudd (Scardinius erythrophthalmus). The caught perch had eaten: Asellus aquaticus, Gammarus lacustris, Corixidae, and the larvae of Chironomidae and Zygoptera.A comparison was made on the invertebrates found in the field and the ones observed from the gut of the perch, and the findings were that the invertebrates that had more occurrence in the gut were less in proportion in the benthic samples. In the laboratory experiment perch ( Perca fluviatilis) was used as the predator fish and the prey organisms were Asellus aquaticus,Gammarus pulex, and Corixidae of three size categories. The results showed that perch handling time for A.aquaticus of the different size categories, was not significantly different (p>0.05); and the same results were valid for Corixidae and G. pulex. However, the intake rate of perch across the prey and their size categories were significantly different. The handling time was not significantly different which means that the predator fish will gain more in terms of intake rate as it prey on larger size prey items, thus harmonizing with the optimum foraging theory. / MSc Ecology and Environmental Science
2

Handläggningstiden vid bygglov : En studie kring kravet i PBL 9:27 / Handling time at permits : A study of the demand in the PBL 9:27

Andersson, Karin, Carmesund, Julia January 2015 (has links)
Genom 2011 års plan- och bygglag (PBL) infördes krav på handläggningstiden för lov och förhandsbesked, vilket tidigare inte funnits i svensk lagstiftning. Enligt PBL 9:27 ska en ansökan om lov handläggas skyndsamt och sökanden ska meddelas beslut inom tio veckor från det att en komplett ansökan har kommit in till byggnadsnämnden. Syftet med kravet var att effektivisera handläggningsprocessen och minska skillnader i handläggningen mellan olika kommuner. I samband med införandet valde man att inte koppla någon sanktion till kravet med motivet att målet med en effektivare handläggningsprocess skulle uppfyllas ändå. Efter flera anmälningar till JO kan man konstatera att kommunerna i flera fall inte uppfyller kravet på en handläggningstid inom tio veckor. Eftersom det inte finns några sanktioner kopplade till kravet kan kommunerna utan risk ta den tid de anser sig behöva för handläggning. Därigenom motverkas även syftet med en enhetlig bygglovsprövning i Sverige. Syftet med studien är att undersöka hur långa handläggningstiderna är vid bygglov. Genom ett omfattande granskningsarbete av bygglovsärenden hos sju kommuner i Västra Götalands län skulle huvudfrågan om kommunerna handläggningstider uppfyller kravet i PBL 9:27 besvaras. Studien avgränsar sig till ärenden från 2014 med åtgärder gällande nybyggnation av byggnad. Materialet sammanställdes i en datamatris för respektive kommun. Utöver datamatrisen fick respektive kommun besvara ett frågeformulär angående arbetsbelastning. Syftet med formuläret var att koppla resultatet från granskningen till hur arbetssituationen såg ut för de anställda under år 2014. Av de 436 granskade ärendena var det 44 ärenden som inte uppfyllde kravet på en handläggningstid inom tio veckor, vilket motsvarar cirka 10 % av antalet granskade ärenden. Av de ärenden som inte uppfyllde kravet i PBL 9:27 var 32 fastigheter belägna inom detaljplan eller områdesbestämmelser och resterande tolv var belägna utanför detaljplanelagt område. Av de 32 ärendena vars fastigheter var belägna inom detaljplan eller områdesbestämmelse innebar 13 ärenden en liten avvikelse från gällande bestämmelser och resterande 19 överensstämde med detaljplanen eller områdesbestämmelserna. Utifrån resultatet är slutsatsen att kommunerna även fortsättningsvis behöver arbeta med sina handläggningstider. Under granskningen noterades även att det brister i kommunernas dokumentation kring viktiga datum och att kommunerna har olika syn på huruvida en ansökan ska anses vara komplett. Förslagsvis bör tydligare riktlinjer upprättas kring dokumentation och när en ansökan ska anses vara komplett. / With Swedish planning and building act (PBL) of 2011 a new demand was adopted for handling time before permits and advance rule, called PBL 9:27. Following PBL 9:27 an application for permits shall be processed promptly and the applicant shall be informed of the decision within ten weeks from the moment a complete application has been submitted to the local building committee. Previously this demand had not been included into Swedish law. The purpose of this demand was to speed up the handling time and to reduce differences in handling time between municipalities. When this demand was adopted a decision was made not to connect it with any form of sanction, should the demand not be met. The argument being that a more effective handling time would be met even without sanctions. Following several notifications to the legal ombudsman one may conclude that in several cases, municipalities do not meet the demand for a handling time within ten weeks. While there are no sanctions connected to the demand municipalities, may without any risk, take as much time they fell needed for the handling of each case. Thereby one of the key purposes of PBL 9:27, that is, reduced differences in handling time between municipalities is counteracted. The purpose of this study is to investigate whether handling time in building permit cases are in compliance with PBL 9:27. In order to answer this question building permit cases were examined thoroughly in seven municipalities in Västra Götaland County. The study has focused cases from 2014 and cases pertaining to construction of buildings. The collected information was compiled in one data matrix for each municipality. Beside of the information compiled in the data matrix each municipality answered a questionnaire focusing workload. The purpose of the questionnaire was to relate the results from the investigation of handling time to a possible explanation, that is, the workload of employees during 2014. Out of 436 examined cases 44 did not meet the demand of handling tie within ten weeks, or approximately 10 % of the cases. Of these 44 cases that did not meet PLB 9:27, 32 were real estates that were located within areas regulated by detailed municipal plans and twelve were located outside of planned areas. Out of the 32 real estates located within planned areas 13 accounted for a minor deviance from the detailed municipal plan while 19 were in compliance with the detailed plan and regulation areas. The results indicate that municipalities need to speed up their handling time for building permit cases regulated by PBL 9:27. An additional result of this study is that several municipalities have flaws in relation to documentation of significant dates. Also, municipalities tend to make different assessments of when an application is considered complete. This study suggests that clearer guidelines are adopted pertaining to documentation of cases and the demands for how to assess if an application is complete.
3

The effect of individual variability and larger carnivores on the functional response of cheetahs

Hilborn, Anne Winona 07 February 2018 (has links)
Functional response is the framework thorough which we can quantify how predator hunting behaviors such as rate of successful attack and time spent handling prey interact with prey density to determine the rate at which prey are killed. Cheetahs are mesopredators and their behavior can be shaped by the need to avoid larger predators while hunting relatively large bodied and mobile prey. I used data from 34 years of observed cheetah hunts in Serengeti National Park in Tanzania to investigate how reproductive condition, prey density, seasonality, and the proximity of larger predators affect cheetah kill rates, probability of successful attack, and time spent handling prey. Mothers with cubs had an asymptotic Type II functional response where kill rate increased but eventually leveled-off at high prey densities, while cheetahs without cubs had a dome shaped Type IV functional response where kill rates actually declined at high prey density. Probability of successful attack on prey was higher for mothers with cubs, and increased slightly with prey density. Mothers with cubs had different prey handling behavior than other cheetahs. Cheetah mothers spend longer at kills then other cheetahs despite the risk that the carcass can attract lions and hyenas that could steal the carcass and potentially kill her cubs. Mothers must make sure their cubs have sufficient time at the carcass to eat their fill, thus they minimize risk from larger predators by being vigilant. In contrast, cheetahs without cubs are unconcerned with cub predation and can eat quickly to minimize the risk of kleptoparasitism. My results show how the pressures of cub rearing and coexisting with larger carnivores differentially shape the hunting behavior of cheetahs, and suggest that intensity of mesopredator suppression may depend on individual variability. This is the first time the functional response for a large mesopredator, has been quantified and the first time a dome shaped response has been recorded in a mammal. My work shows the value in accounting for individual variability in functional response and how linking of carnivore hunting behavior to multiple species interactions advances our understanding of how classical ecological theory applies to wild ecosystems. / Ph. D.
4

Optimization of design efficiency by implementing Design for Excellence : A Case Study for Optimizing Rottne Industri AB:s current harvester cabin production / Optimering av konstruktionseffektivitet genom implementering av Design for Excellence : En fallstudie för att optimera Rottne Industri AB:s nuvarande skördarhyttsproduktion

Berggren Turesson, Adam, Holmberg, Alex January 2023 (has links)
The effects of humanity's actions on the environment have been a viral topic for many years. The efficiency of refining raw materials is crucial in reducing these effects. This thesis was thereby tasked with improving the assembly efficiency of Rottne Industri AB:s harvester cabin. Various theories were utilized to improve the design, with Design for Excellence being the most notable. By implementing a seven-step product development process, concepts could be generated and later scored based on the customer's comments and discovered issues. The authors selected the idea with the highest score and developed it until they achieved a concept meeting the product's objectives. The concept was then validated by performing simulations and calculations related to its assembly efficiency, environmental impact, and cost. The redesign resulted in an idea possessing a design efficiency 135% higher than the original, a 72% shorter assembly time, 13% less weight, a 25% reduction in greenhouse gas emissions, and a 41% reduction in assembly and material costs.

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