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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.
21

Strategy to tag Actin II in Plasmodium berghei

Cinarli, Pembe January 2018 (has links)
Malaria is a disease that is caused by parasite called Plasmodium spp. and trasmitted by female Anopheles mosquitoes to the host. The disease has great impact around the world and there are half a million deaths and several hundred million infections every year. Studies revealed that there are two actin isoforms in the parasite, actin I and actin II. Absence of actin II has severe effect on the development of the parasite in the mosquito but the molecular function is still unknown. Identification of interacting proteins is of great importance to understand further the function of the protein. To achieve this goal actin II has to be enriched and this required a tagged version of the protein. In this project purification of the protein was to be achieved through biotinylation. In this method the protein of interest is biotinylated by BirA ligase in the cell and is then purified by , streptavidin. The project involved transfection of vector for Plasmodium berghei, containing the BirA gene and a stage-specific promoter (cdpk4). The construct was integrated in the chromosomal locus Sil6 and introduced to wild-type and actin II knock out parasites. Genotyping by PCR revealed integration of the insert in wild type parasites and phenotypic anaylsis showed no difference between BirA wild type and wild type control parasites. The expression of the BirA ligase in the parasite was investigated with Western blot but no signal was detected.
22

Effects of a fish farm on downstream macroinvertebrates

Thoresson, Joakim January 2018 (has links)
The number of fish farms is increasing worldwide tomeet the global demand for fish used as a food source for humans. The WorldBank predicts that by 2030, 62 percent of all consumed fish globally will beproduced in fish farms. Due to this increasing demand for fish, fish farming isa growing business and the numbers of fish farms are increasing. Today, thereare fish farms situated in more than one hundred municipalities in rural partsof Sweden. Fish farms may besituated in hydropower plant reservoirs, which have been foundto be suitable locations for cage fish farming. However, environmental concernshave been raised regarding excess dissolved nutrients from fish farms thatmight enrich downstream ecosystems. The source of this enrichment is primarilyfish feces and uneaten fish feed, which contain both nitrogen and phosphorus. The overall objective of this study is to evaluate the effects of a largefish farm located in north-central Sweden on the downstream river ecosystem. Todo this, I compared benthic macroinvertebrate diversity, functional feedinggroup representation, community composition, and indices of biotic integritybetween a site downstream of a fish farm and a nearby (control) reach withoutan upstream fish farm. No significant difference between these sites wasobserved for any metric accept for the species richness, but due to the lowreplication results should be interpreted with caution. Further studies areneeded to assess the possible impact of fish farms on the water quality andecological health of rivers.
23

Relation between herbivore abundance, herbivore diversity and vegetation diversity

Lundgren, Andreas January 2018 (has links)
No description available.
24

Fatigue analysis - system parameters optimization

Markgren, Hanna January 2018 (has links)
For a mechanical system exposed to repeated cyclic loads fatigue is one of the most common reasons for the system to fail. However fatigue failure calculations are not that well developed. Often when fatigue calculations are made they are done with standard loads and simplified cases. The fatigue life is the time from start of use until the system fails due to fatigue and there does exist some building blocks to calculate the fatigue life. The aim for this project was to put these building blocks together in a workflow that ca be used for calculations of the fatigue life. The workflow was built so that it should be easy to follow for any type of me- chanical system. The start of the workflow is the load history of the system. This is then converted into a stress history that is used for the calculations of the fatigue life. Finally the workflow was tested with two test cases to see if it was possible to use. In Algoryx Momentum the model for each case was set up and then the load history was extracted for each time step during the simulation. To convert the load history to stress history FEM calculations was needed, this was however not a part of this project so the constants to convert loads to stress was given. Then with the stress history in place it was possible to calculate the fatigue life. The results from both test cases were that it was possible to follow every step of the workflow and by this use the workflow to calculate the fatigue life. The second test also showed that with an optimization the system was improved and this resulted in a longer lifetime. To conclude the workflow seems to work as expected and is quite easy to follow. The result given by using the workflow shows the fatigue life, which was the target for the project. However, to be able to evaluate the workflow fully and understand how well the resluts can be trusted a comparison with empiric data would be needed. Still the results from the tests are that the workflow seem to give reasonable results when calculating fatigue life.
25

Radiation exposure to personnel during fluoroscopic procedures : Strålningsmiljö för personal under genomlysningsarbete

Eriksson, Olof January 2018 (has links)
There are about 17 million X-ray procedures performed in Sweden every year. Various methods are used to determine the risk for the patient, and for the staff. The objective of this project was to map X-ray scatter coming out of a patient as a result of interactions between the radiation and body tissue during certain medical procedures that involve fluoroscopy. Flouroscopy is a type of X-ray imaging method that generates a moving picture which allows an operator to view in-body procedures live. A successfully created map of the radiation field can work as a tool for risk analysis concerning the dose of radiation of which the medical staff is exposed to, this parameter will later be described as the effective dose (E). The effective dose is a tool for assessment of the risk of developing lethal cancer due to radiation exposure. This report will also investigate the radiation that reaches the eye lens of the staff, since the maximum recommended dosage for the eye lens has been lowered recently when it was discovered that the eye lens was more sensitive to radiation than previously known. In this report data was collected from radiation exposure situations, and it was concluded that distance is a good protector against radiation, which agree well with theory discussed in the report. Another theory which was discussed in the paper states that positions behind the X-ray tube will be exposed to the highest amount of radiation, this was also proven. The measured data from investigating protective equipment showed that the equipment in place was effective. / <p>The author changed last name to Folkunger due to marriage shortly after this publication.</p>
26

Volume calculation of the thyroid gland from SPECT images based on Monte Carlo simulations

Niklas, Palmqvist January 2018 (has links)
In this study the volume determination which is a part of the doseplanning for patients with thyrotoxicosis was investigated. The aim was to find an accurate method to determine the active volume with single photon emission tomography (SPECT) which in several studies have shown better results than with the currently used method planar scintigraphy (PS). This was implemented on the Xeleris 3.1 by General Electric (GE) at the University Hospital of Umeå (NUS). The examination time with SPECT is required not to be significantly longer than the examination time with PS. Despite the relatively short examination time, the accuracy of the volume determination should be more accurate. This was analyzed with a true value of the volume, conducted with Monte Carlo simulations of digital anthropomorphic phantoms. It is also important that the developed method is user friendly. The study included ten patients with thyrotoxicosis from which, relative activity uptakes were measured. These uptakes were specified in 22 digital XCAT phantoms which were random sampled with respect to phantom mass. The Monte Carlo program "simulating medical imaging nuclear detectors" (simind) was used to simulate the SPECT-system. The projection images were ordered subset expectation maximization (OSEM) reconstructed and Butterworth filtered. Unfiltered images were used to compare volume calculations with filtered ones. The volume of the thyroid was segmented using threshold values applied to all voxels in the image-sets and the optimization of the thresholds was conducted by numerical calculations. The results in this study shows that the best choice of intensity threshold value is 21.1(24)% of the maximum voxel value for all phantoms. The threshold is valid for OSEM iteration number five and unfiltered image-sets. Butterworth filtered images were less suitable to use than unfiltered images when the thyroid volume was calculated with data from SPECT-simulations of phantoms.
27

Investigation of developmental neurotoxic effects of exposure to a combination of methylmercury and chlorpyrifos

Forslund, Annica January 2018 (has links)
No description available.
28

Using Boosted Decision Trees in the Search for Heavy Neutral Higgs Bosons in the ATLAS Experiment

El Faham, Hesham January 2018 (has links)
A search for heavy neutral Higgs bosons in the τ_μ τ_had channel is presented. The analysis was performed using approximately 32 fb^−1 of 13 TeV proton-proton collision data with the ATLAS detector and improves upon earlier ATLAS searches through the use of Boosted Decision Trees (BDT).
29

Optimizing fuel cell channel geometry to favour water transport / Optimera bränslecellkanalgeometri for att gynna vattentransport

Linder, Tom January 2017 (has links)
No description available.
30

Dyonic supersymmetric solutions in supergravity

Rødland, Lukas January 2017 (has links)
No description available.

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