To see the other types of publications on this topic, follow the link: Magnetic survey.
Dissertations / Theses on the topic 'Magnetic survey'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Magnetic survey.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Braccio, Peter G. "Survey of trapped plasmas at the earth's magnetic equator." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28584.
Full text
2
Yee, Chin-ming. "Magnetic and gradiometer survey of a site in northeastern Lantau Island Hong Kong." Click to view the E-thesis via HKUTO, 2002. http://sunzi.lib.hku.hk/hkuto/record/B43895025.
Full text
3
Macke, Robert J. "Survey of meteorite physical properties density, porosity and magnetic susceptibility." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4653.
Full textAbstract:
Grain density and magnetic susceptibility, which have been shown to distinguish H, L and LL ordinary chondrites, also may distinguish shergottites, nakhlites and chassignites from each other, but the two groups of enstatite chondrites (EH and EL) remain indistinguishable in these properties. H chondrite finds exhibit a slight negative trend in porosity with increasing petrographic type, and all chondrite falls together exhibit a pronounced negative trend in porosity spanning all petrographic types. The overall trend corresponds roughly to a positive trend in porosities with respect to both degree of oxidation and percentage of matrix. It also corresponds to the macroporosities of analogous asteroids. These traits constrain models of conditions in the solar nebula and the formation of chondrite parent-body precursors.; The measurement of meteorite physical properties (i.e. density, porosity, magnetic susceptibility) supplements detailed chemical and isotopic analyses for small samples (thin sections or ~300 mg portions) by providing whole-rock data for samples massing in the tens of grams. With the advent of fast, non-destructive and non-contaminating measurement techniques including helium ideal-gas pycnometry for grain density, the Archimedean "glass bead" method for bulk density and (with grain density) porosity, and the use of low-field magnetometry for magnetic susceptibility, all of which rely on compact and portable equipment, this has enabled a comprehensive survey of these physical properties for a wide variety of meteorites. This dissertation reports on the results of that survey, which spanned seven major museum and university meteorite collections as well as the Vatican collection. Bulk and grain densities, porosities and magnetic susceptibilities are reported for 1228 stones from 664 separate meteorites, including several rare meteorite types that are underrepresented in previous studies. Summarized here are data for chondrites (carbonaceous, ordinary and enstatite) and stony achondrites. Several new findings have resulted from this study. From the use of a "weathering modulus" based on grain density and magnetic susceptibility to quantify weathering in finds, it is observed that the degree of weathering of ordinary chondrites is dependent on their initial porosity, which becomes reduced to less than ~8% for all finds, but for enstatite chondrites weathering actually increases porosity.ID: 029050619; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references (p. 299-311).
Ph.D.
Doctorate
Department of Physics
Sciences
4
Yee, Chin-ming, and 庾前明. "Magnetic and gradiometer survey of a site in northeastern Lantau Island Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B43895025.
Full text
5
Amin, Mohammad Mehdi, Bijan Bina, Amir Masood Samani Majd, and Hamidreza Pourzamani. "Survey of Recycled Nano Magnetic Particle in Benzene Removal from Aqueous Solution." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35596.
Full textAbstract:
The removal of benzene, a hazardous monoaromatic compound, from aqueous solution by recycled nano
magnetic particle (NM) Fe3O4 in batch condition was evaluated. Regeneration studies verified that the
benzene adsorbed by the NM could be easily desorbed by temperature. So that the benzene removal
efficiency was 98.7 % for raw NM, 97.8 % for first recycled NM and 97.4 percent for second recycled NM. It
is expected that the Fe3O4 nanoparticles with fine grain size (20-30 nm) will be used as one of effective,
convenient and low-costing methods for removal and recovery of benzene from water and wastewater.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35596
6
Wedmark, Mats. "A small scale, high resolution magnetic survey at the archaeological site of Birka, Sweden." Thesis, Uppsala universitet, Geofysik, 1999. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-303228.
Full textAbstract:
A high resolution magnetic survey was carried out at the archaeological site of Birka, situated approximately 20 km west of Stockholm. A new-generation optically pumped cesium magnetometer, G-858 from Geometrics, with a maximum sensitivity of 0.01 nT was used in the survey. An area of totally 504 m2 was covered in three windy days in September 1997 with the cesium magnetometer working in vertical-gradient mode. Remnants of the old houses, some of the oldest ditches and an earlier excavation could be seen in the gradient data after processing. Also a total-field measurement was carried out to search for the oldest defence wall at Birka. The bad positioning that followed with the continuous-scan mode made the data very difficult to process efficiently. Some processing was done in Matlab to eliminate effects that might be caused by the geology, but no substantial archaeological results emerged.This work shows that high resolution magnetic surveys can be efficient in detecting archaeological remains even in a very heterogeneous soil, provided very sensitive equipment and correct choice of method. It also emphasized the importance of good positioning in a survey.
7
Houser, Tiffany. "Assessment of Magnetic Resonance Imaging Safety: Allied Health Professional Clinical Competence." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etd/3549.
Full textAbstract:
Magnetic resonance imaging is a major advancement in the diagnostic imaging field. Most patients can tolerate an MRI however, there are some who are unable to complete a lengthy scan while lying completely still without sedatives or anesthesia. Non-MRI healthcare providers are trained to use equipment that is “unsafe” in the MRI suite due to the strong magnetic field. Staff who are not fully knowledgeable and trained in MRI safety measures can endanger staff and patients.
The purpose of this study was to determine the knowledge level of non-MRI healthcare providers regarding safety risks associated with MRI and to determine their level of satisfaction regarding the MRI safety training they received. This study concluded that non-MRI healthcare providers are knowledgeable about most of the safety hazards. They are satisfied with annual training but would like more in-depth material added to their current learning modules.
8
Bof, Marcel. "La gradientmétrie en aéromagnétisme haute sensibilité." Grenoble 1, 1986. http://www.theses.fr/1986GRE10041.
Full textAbstract:
Un systeme de deux oiseaux separes de 50m tracte sous helicoptere a ete experimente pour evaluer les problemes poses par un gradientmetre a base longue. En vol, la geometrie variable du dispositif introduit un probleme de positionnement relatif des oiseaux aborde par des techniques de reperage radioelectrique et par les moyens de la visionique. Conception d'oiseaux instrumentes pour le positionnement et l'altitude
9
Yehuwalashet, Ezra. "Gravity and Magnetic Survey, Modelling and Interpretation in the Blötberget Iron-Oxide Mining Area, Bergslagen, Sweden." Thesis, Uppsala universitet, Geofysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-305964.
Full textAbstract:
The Blötberget mining area, the focus of this MSc project, is located about 230 km northwest ofStockholm and 12 km southwest of the city of Ludvika (central Sweden). The mining area has beenknown since 1600 for its various types of mineralization particularly iron-oxide deposits (magnetite andhematite) with the mining commenced in 1944. Previous geoscientific research in the area providesdetailed information about lithological variations and structure of the bedrock near the surface.However, knowledge of the depth extent of the mineral deposits and their host rocks is limited. To shedlights on these issues and support deep mineral exploration potential in the study area, within the recentlylaunched StartGeoDelineation project, new ground gravity data, 180 data points on average 150 m apart,were collected during two field campaigns in 2015 and 2016. Aeromagnetic data were obtained fromthe Geological Survey of Sweden (SGU) to complement the ground gravity measurement interpretationsand modelling. After a careful inspection of the field gravity data, they were reduced to completeBouguer anomaly with a maximum error estimate of about 0.6 mGal due to uncertainty in theinstrumental drift, slab density, geodetic surveying, diurnal variations and terrain (or topography)correction. The Bouguer gravity data after separation of regional field (second order polynomial at theend was used) were used (~ 8 mGal range) for interpretation and 3D inverse modelling. Clear anomalouszones are noticeable in the gravity data particularly due to mineralization and a major boundaryseparating a gravity low from gravity high in the southern part of the study area likely representing afault boundary separating two different lithological units. In my study, both forward and inversemodelling using rudimentary objects/shapes and voxel-type (mesh) approach were carried out. Effect ofinitial and reference models were tested on both gravity and magnetic datasets. While the constrainedmodels have still significant ambiguity, they help to suggest structural control on the location ofmineralization and may allow estimating an excess tonnage due to the presence of mineralization in thestudy area. Due to access limitations (e.g., unable to measure on the water-filled pit) the gravity modelis sensitive to the measuring positions and constraints using known shape of mineralization was not atthe end successful to overcome this. Collecting more gravity data on the target area and repeated test of3D inversion by adjusting the inversion parameters might help to improve the final result.Gruvområdet Blötberget som denna MSc avhandling är fokuserat kring ligger 230 km från Stockholm,12 km från Ludvika, i Bergslagen. Mineralförekomster, framförallt järnmalm (magnetit och hematit)har varit kända i området sedan 1600-talet, och storskalig brytning inleddes år 1944. Tidigare geologiskaundersökningar i området har gett detaljerad information om fyndighetens ytnära litologi och struktur.Hur långt ner förekomsten och moderbergarten sträcker sig har dock varit okänt. Som del av detnystartade projektet StartGeoDelineation utfördes marknära gravimetrimätningar. Totalt 180 mätpunkter,med ett medelavstånd av 150 m, samlades in under två fältkampanjer under 2015 och 2016.Vid modellering komplementades gravimetridata med magnetometridata, insamlad under flygmätningarutförda av Sveriges geologiska undersökningar (SGU). Efter noggrann bearbetning av gravimetridatatogs den kompletta bougeranomalin fram. Det uppskattade felet är ca 0.6 mGal och är till följd avosäkerhet i korrigeringar för drift hos instrument, dygnsvariation, geodesi och topografi. Efter korrigeringav regional trend (uppskattad från 2:a ordningens pylonom, och med satt skala av 8 mGal somresultat) gjordes en 3D modell, via inversionsalgoritmer, samt en tolkning. Det står klart av framförallti gravimetridatan att det finns två avvikande zoner. Dessa indikerar mineraliseringen och en gräns i densödra delen av undersökningsområdet med gravimetridata i låg respektive höga värde. Detta återspeglartroligtvis också en förkastningszon mellan två lithologiska enheter. I denna studie har enkla geometriskaformer och voxlar (mesh) använts för bådadera forward modellering och inversionsalgoritmer. Deursprungliga och referensmodellerna testades på både dataset för gravitmetri och magnetometri. Trotsatt modellerna fortfarande visar tvetydiga resultat så kan de ändå användas för att ge förslag på struktureroch läge för mineraliseringen, och skall även kunna användas för att uppskatta tonnage. Det sistnämndakunde dock inte uppnås då punktäthet i mätdatan, till följd av att det numera vattenfyllda dagbrottet intekunde inkluderas i mätområdet, och att formen av mineraliseringen inte kunde avgränsar på etttillfredsställande sätt. För en förbättring av resultaten bör fler mätpunkter till gravimetridata samlas in iområdet så att 3D-modelleringen kan förbättras genom upprepade justeringar av inversionsparametrarna
StartGeoDelineation
10
Wade, G. A., C. Neiner, E. Alecian, H. H. Grunhunt, V. Petit, B. Batz, D. A. Bohlender, et al. "The MiMeS Survey of Magnetism in Massive Stars: Introduction and Overview." Digital Commons @ East Tennessee State University, 2015. https://dc.etsu.edu/etsu-works/2723.
Full textAbstract:
The MiMeS (Magnetism in Massive Stars) project is a large-scale, high-resolution, sensitive spectropolarimetric investigation of the magnetic properties of O- and early B-type stars. Initiated in 2008 and completed in 2013, the project was supported by three Large Program allocations, as well as various programmes initiated by independent principal investigators, and archival resources. Ultimately, over 4800 circularly polarized spectra of 560 O and B stars were collected with the instruments ESPaDOnS (Echelle SpectroPolarimetric Device for the Observation of Stars) at the Canada–France–Hawaii Telescope, Narval at the Télescope Bernard Lyot and HARPSpol at the European Southern Observatory La Silla 3.6 m telescope, making MiMeS by far the largest systematic investigation of massive star magnetism ever undertaken. In this paper, the first in a series reporting the general results of the survey, we introduce the scientific motivation and goals, describe the sample of targets, review the instrumentation and observational techniques used, explain the exposure time calculation designed to provide sensitivity to surface dipole fields above approximately 100 G, discuss the polarimetric performance, stability and uncertainty of the instrumentation, and summarize the previous and forthcoming publications.
11
Fidler, Michael L. "Three dimensional digital analysis of 2,500 square kilometers of gravity and magnetic survey data, Bellefontaine Outlier area, Ohio /." Columbus, Ohio : Ohio State University, 2003. http://hdl.handle.net/1811/6110.
Full text
12
Savostyanova, Natalia, and Valeriya Velichko. "Plastic card frauds, a survey of current relevant card and system properties." Thesis, Linköping University, Department of Electrical Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2424.
Full textAbstract:
Recently the society has been turning from the use of paper-based technologies to plastic cards in certain spheres of our life. With the emergence and proliferation of high technologies we cannot content with the security provided bypaper only. Therefore the society has chosen plastic to protect its information because it offers far more security based not only on human perception but also on machine-readable elements.
The number of plastic cards in circulation in different spheres of our everyday life increases constantly. They replace money, documents and allow easy and safe access to some services. In spite of its security the plastic card however is subjected to fraud.
Plastic card fraud results in significant losses for the various industries. Since the first appearance of plastic cards methods of committing fraud have changed dramatically. Now there is a wide range of high technologies at the disposal of criminals as well as card manufacturers.
Therefore we have put the great emphasize of this work on the analysis of the most common card technologies in the Plastic Card World, the magnetic stripe and the chip, existing crimes and main means of their committing. And we also have revealed the weak and strong sides of the prevention techniques, which are currently in use.
13
Davi, Daniela L. "A geological interpretation of a high resolution ground magnetic survey, and its relationship to a regional scale, Tumby Bay, South Australia /." Title page, contents and abstract only, 1993. http://web4.library.adelaide.edu.au/theses/09S.B/09s.bd249.pdf.
Full textAbstract:
Thesis (B. Sc.(Hons.))--University of Adelaide, Dept. of Geology and Geophysics, 1994?Two maps have overlays. National grid reference: Tumby Bay Sheet SI53-10 (1:50,0 00-III) geological map. Cover title: "A structural interpretation of a detailed ground magnetic survey, Burrawing area, Tumby Bay, South Australia. Includes bibliographical references (leaves 32-33).
14
Richardson, Paul D. "Pluton Zonation Unveiled by Gamma-ray Spectrometry and Magnetic Susceptibility; A Case Study of the Sheeprock Granite, Western, Utah." BYU ScholarsArchive, 2004. https://scholarsarchive.byu.edu/etd/209.
Full textAbstract:
A radiometric survey of the zoned 21 Ma, A-type Sheeprock granite, western Utah, combined with measurements of magnetic susceptibility and field observations were analyzed using a geographic information system. The intrusion spans 25 square km and is roughly eliptical in shape with its long axis trending northwest. Concentration maps (composed of more than 500 survey stations) of eU, eTh, texture, magnetic susceptibility, color, and joint density help to constrain magmatic and post-magmatic processes related to its chemical and physical zonation. Uranium ranges from 3.9 to 26.9 ppm (mean 12.7) and thorium from 1.7 to 125.7 ppm (mean 45.5). Similarities in spatial patterns and near normal distributions of U and Th imply minimal remobilization and secondary equilibrium of U. Relatively high magnetic susceptibility (6 to 12*10^-3 SI units), low eU and eTh, and limited whole rock chemical anayses show the southeastern part of the pluton is more mafic and most likely formed as an early cumulate. Dominant textures are porphyritic with a fine-grained matrix along the northeastern margin, coarsening to a medium-grained matrix along the southwestern margin. This transition from fine to medium-grained matrix textures is believed to be a preserved solidification front that had migrated from the roof and walls inward during cooling. Late stage magma mixing is evidenced by a string of mafic enclaves along the axis of the pluton near this solidification front. eU and eTh generally increase toward the finer-grained northeastern margin of the pluton. This has been interpreted to be the primary result of fractionation of U and Th into monazite and thorite. As mafic cumulates formed along the northeastern margin residual liquids were displaced inward. This depleted the more evolved parts of the pluton in U and Th. Beryl, a distinquishing characteristic of the most evolved portions of the pluton, is concentrated in two areas along the central axis of the intrusion. The intrusion is a cumulative of three magmatic phases, the second of which crystallized from the margins inward. Joint spacing is a major factor in controlling post-magmatic processes. The pluton has a higher density of joints (10 cm apart) near the upper margins, and fewer joints (> 1 meter apart) at lower elevations. Differential cooling and magma pressures are believed to have controlled the varying joint densities. Increased alteration, oxidation, and red-staining are more prevalent in areas of higher joint density. Magnetic susceptibility is bimodal. The high mode (5.4*10^-3 SI) is on the low end of magnetite-series granites and occurs most often in the white granite. The low mode (0.07*10^-3 SI) implies significant post-magmatic oxidation and the destruction of magnetite and correlates to the red granite. Truncated chemical and textural patterns along the pluton's northwestern margin support evidence for range front normal faulting.
15
Brady-Rawlins, Kathleen L. "The O.C. Voss Site: reassessing what we know about the Fort Ancient occupation of the central Scioto drainage and its tributaries." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1180454140.
Full text
16
Viberg, Andreas. "Remnant echoes of the past : Archaeological geophysical prospection in Sweden." Doctoral thesis, Stockholms universitet, Institutionen för arkeologi och antikens kultur, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-79239.
Full textAbstract:
The aim of this thesis has been to investigate the benefits, pitfalls and possibilities of using geophysical methods in archaeological projects. This is exemplified by surveys carried out at archaeological sites in different geographical and chronological contexts. The thesis also aims at investigating the cause for the under-use of the methods in Swedish archaeology by looking at previously conducted surveys. The methods used during these surveys have been Ground-penetrating radar (GPR), magnetometer, slingram and a kappameter. The surveys in the mountain tundra region of Lapland show that magnetic susceptibility surveys is a valuable aid in discovering heaps of fire-cracked stones and when combined with magnetometry, also hearths. GPR and magnetometer surveys within the Migration Period ringfort Sandbyborg provided the spatial layout of the fort and indicated, along with results from recent excavations and metal detections, many similarities with the ringfort Eketorp II. The non-magnetic character of the sedimentary bedrock on Öland and Gotland is suitable for magnetometer surveys and the method is also highly appropriate for the detection of the remains of high-temperature crafts. GPR surveys at St. Mary’s Dominican convent in Sigtuna produced the spatial layout of the central cloister area. The investigations also show that the geology, pedology, land use and the character of commonly occurring prehistoric remains in Sweden, in certain circumstances and in certain areas, have restricted the possibility of successfully carrying out geophysical surveys. Care must therefore be taken to choose the right instrument for the survey and to tailor the sampling density of each geophysical survey, according to the character and size of the expected archaeological remains, in order to maximize their information return. To increase the use of geophysical methods in Sweden the educational opportunities, both for surveyors and professional archaeologists, need to improve.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Manuscript.
17
Alkhatib-Alkontar, Rozan. "Magnétisme des villes circulaires du troisième millénaire avant J.C dans les marges arides de la Syrie." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAH022/document.
Full textAbstract:
À l’heure actuelle, la prospection magnétique est reconnue comme une méthode efficace pour répondre à des problématiques archéologiques en partie du fait de sa capacité à détecter les structures enfouies (bâtiments, fosses, canaux, etc,…). Elle permet de mettre en évidence et de localiser avec précision les structures et elle est donc une aide précieuse avant le début des opérations de fouilles. Notre travail rend compte de cartographies magnétiques effectuées sur trois sites archéologiques en Syrie (Al-Rawda, Sh’airat, Malhat Ed-Deru) en utilisant deux méthodes de cartographie magnétique à différents niveaux de résolution. La première méthode (à la perche) permet de couvrir de grandes surfaces rapidement et la deuxième méthode (à la luge), plus lente, permet de mieux imager les structures enfouies. Ces méthodes fournissent des plans urbanistiques des villes circulaires du troisième millénaire avant J.C. Les opérateurs de méthodes potentielles et la modélisation ont permis de caractériser la géométrie des structures aimantéesCurrently, magnetic surveying is recognized as an effective method to address archaeological issues in part because of its ability to detect buried structures (buildings, pits, channels, etc ...). It allows identifying and accurately locating structures and is therefore a valuable aid before the commencement of excavation. Our work reports on magnetic mapping done at three archaeological sites in Syria (Al-Rawda, Sh’airat, Malhat Ed-Deru) using two methods of magnetic mapping at different levels of resolution, The first method (Backpack) allows to cover large areas quickly and the second method (Sledge), slower, allows better imaging of buried structures. These methods have provided urban planning circular cities of the third millennium BC. The modeling method swapped to characterize the magnetic sources
18
Doll, Stefan. "Development of a magnetic intra-uterine manipulator." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/19935.
Full textAbstract:
Thesis (MScEng)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Uterine manipulation is integral to obtaining adequate access to the uterus during a laparoscopic procedure. A variety of mechanical manipulators have been developed to aid the surgeon with the dissection of the uterus during laparoscopic hysterectomies. Limitations of existing manipulators are that they require an additional assistant during surgery, are expensive and may cause tissue trauma to the vaginal or cervical canal. This study introduces the novel concept of a magnetic uterine manipulator, intended to overcome existing devices’ shortcomings and enabling non-invasive uterine manipulation. The first goal of the study was to investigate the strengths and weaknesses of existing mechanical manipulators and compare them to those of a magnetic device. Analysis showed that a magnetic manipulator would not be able to compete in terms of the range of motion of existing devices. A limited anteriorsagittal rotation range of 60 was seen in the magnetic manipulator compared to a range of 140 in mechanical devices. However, the magnetic manipulator could eliminate the need for an extra assistant, is reusable and thus also more economical. The second goal was to investigate which type of setup would be most successful at effective uterine manipulation. Through concept analysis a cart-on-arch system was deemed most effective. To lift an effective load of 1 N over an air-gap of 150 mm rare-earth N38 Neodymium (NdFeBr) magnets showed the most promise as magnetic actuators. FEA (Finite Element Analysis) simulations of the magnetic setup were validated experimentally which produced an acceptable MAE (mean absolute error) of 0.15 N. Furthermore, a comparative simulation study of shielded and unshielded magnets was done which concluded that shielded magnets produce a slightly higher attraction force and would be safer to use due to less magnetic flux fringing. Thirdly and lastly, potential safety hazards and risks of using magnetic actuators in surgical environments were identified. The literature research revealed that connections between magnetic fields and health risks to patients have not been conclusively proven in clinical studies to date, but nonetheless, great care should be taken in situations where the patient has a pace-maker or orthopaedic implants, as these might interact with the magnetic field. Recommendations for future work include further research into the geometry and scaling effects of magnetic shielding as well as electromagnetic actuator design. Electromagnetic actuators could replace rare-earth magnets, if coil and cooling systems are optimized, resulting in magnets that can be reversed or switched off and which are therefore easier to control and safer to handle.
AFRIKAANSE OPSOMMING: Ontwikkeling van ’n Magnetiese Intra-Uteriene Manipuleerder Baarmoedermanipulasie is van uiterste belang om sodoende voldoende toegang te kry tot die baarmoeder gedurende ’n laparoskopiese prosedure. Daar is reeds ’n verskeidenheid meganiese manipuleerders ontwikkel as hulpmiddel vir die chirurg in die ontleding van die uterus tydens laparoskopiese histerektomies. Beperkings van bestaande manipuleerders is dat ’n bykomende assistent tydens chirurgie benodig word. Die manipuleerders is ook duur en kan weefseltrauma veroorsaak aan die vaginale of servikale kanale. Die studie stel ’n nuwe konsep bekend: ’n magnetiese baarmoedermanipuleerder, gemik daarop om bestaande toestelle se tekortkominge te oorkom en nie-indringende baarmoedermanipulasie moontlik te maak. Die eerste doel van die studie was om die voordele en nadele van bestaande meganiese manipuleerders te ondersoek en dit te vergelyk met dié van die magnetiese toestel. Analise het getoon dat ’n magnetiese manipuleerder nie met bestaande toestelle sal kan kompeteer waar dit gaan om beweegruimte nie. Daar is ’n beperkte anterior-sagitale rotasiespeling van 60 in die magnetiese manipuleerder, terwyl die meganiese toestel ’n rotasiespeling van 140 het. Die magnetiese manipuleerder kan egter die nodigheid van ’n bykomende assistant uitskakel, is herbruikbaar en dus ook meer ekonomies. Die tweede doel van die studie was om die tipe opstelling wat meer suksesvol sal wees tydens doeltreffende baarmoeder manipulasie te ondersoek. Konsep-analise het getoon dat ’n "cart-on-arch"stelsel die beste sal werk. N38 Neodimium (NdFeBr) magnete het die beste vertoon as magnetiese aandrywer om ’n werklike belasting van 1 N oor ’n lugspasie van 150 mm te lig. EEA (Eindige Element Analise) simulasies van die magnetiese opstelling is eksperimenteel bekragtig en het ’n aanvaarbare gemene absolute fout (GAF) van 0.15 N gelewer. ’n Vergelykende simulasie studie het verder gewys dat beskutte magnete ’n effens hoër aantrekkingskrag oplewer en sal dus veiliger wees om te gebruik vanweë die verminderde magnetiese stromingsrand. Derdens en laastens is potensiële veiligheidsrisikos en gevare in die gebruik van magnetiese drywers in chirurgiese omgewings geïdentifiseer. Literatuurnavorsing het onthul dat die verband tussen magneetvelde en gesondheidsrisikos aan pasiënte nog nie voldoende bewys is in kliniese studies tot op datum nie. Gevalle waar pasiënte ’n pasaangeër of ortopediese inplantings het moet met groot sorg hanteer word aangesien dit dalk kan reageer met die magneetvelde. Aanbevelings vir toekomstige werk sluit verdere navorsing in in die rigting van die geometrie en die afskilferingseffek van magnetiese beskutting en ook elektromagnetiese drywer ontwerp. Elektromagnetiese drywers kan moontlik rou aarde magnete vervang indien winding en afkoelstelsels ge-optimeer word wat kan lei tot magnete wat omgekeer of afgeskakel kan word en dus makliker beheerbaar is en veiliger om te hanteer.
19
St-Laurent, Lemerle Alexandre. "Analysis of Mars Global Surveyor magnetic data : crustal and time-dependent external magnetic fields." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101653.
Full textAbstract:
In this thesis, Mars Global Surveyor mapping-phase magnetic data are used to derive a combined spherical harmonic model of both Martian crustal and time-dependent external magnetic fields.A 60-degree spherical harmonic model of the crustal magnetic anomalies is first isolated, by averaging of in-shadow data over 0.5° x 0.5° latitude and longitude bins, and covariance analysis between multiple independent models. This model is then subtracted, separately, from day-side and night-side measurements. External residual data are expended in terms of now time-dependent 30-degree spherical harmonics, using 1 year and 1/2 year periods, and with separate internal and external radial dependencies. Independent Fourier series expansions allow to validate the temporal variations of the preceding model.
As a result, I obtain, along with the crustal anomaly maps, the spatial distribution of the external fields, their steady-state features, and the amplitude maps of their yearly and half a year variations, separately for day and night sides of Mars. Although the maxima of the temporal amplitudes show good correlations with the strong crustal anomalies, there are significant differences between them.
Keywords. covariance analysis, crustal anomalies, magnetic anomalies, magnetic field, magnetosphere, Mars, Mars Global Surveyor, spherical harmonics, temporal amplitudes
20
Munschy, Marc. "Etude geophysique detaillee du point triple de rodriguez et de la zone axiale des trois dorsales associees (ocean indien)." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13057.
Full textAbstract:
L'etude geophysique detaillee (bathymetrie seabeam, gravimetrie, magnetisme) du point triple rodriguez et d'un segment de la zone axiale des trois dorsales oceaniques associees situe a environ 400 km du point triple, a permis de realiser des cartes bathymetriques, gravimetriques et magnetiques de ces quatre zones qui representent des surfaces d'environ 8500 km**(2)
21
Hegmann, Mary Jane. "Gravity and magnetic surveys over the Santa Rita Fault System, southeastern Arizona." Thesis, The University of Arizona, 1998. http://hdl.handle.net/10150/278675.
Full textAbstract:
Gravity and magnetic surveys were performed in the northeast portion of the Santa Rita Experimental Range, in southeastern Arizona, to identify faults and gain a better understanding of the subsurface geology. A total of 234 gravity stations were established, and numerous magnetic data were collected with portable and truck-mounted proton precession magnetometers. In addition, one line of very low frequency electromagnetic data was collected together with magnetic data. Gravity anomalies are used to identify two normal faults that project northward toward a previously identified fault. The gravity data also confirm the location of a second previously interpreted normal fault. Interpretation of magnetic anomaly data indicates the presence of a higher-susceptibility sedimentary unit located beneath lower-susceptibility surficial sediments. Magnetic anomaly data identify a 1-km-wide negative anomaly east of these faults caused by an unknown source and reveal the high variability of susceptibility in the Tertiary intrusive rocks in the area.
22
Al-Ghamdi, Ahmad Hamoud. "Staging of lung cancer by magnetic resonance imaging." Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326783.
Full text
23
Scaringi, Simone. "Machine learning from hard X-ray surveys : applications to magnetic cataclysmic variable studies." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/161197/.
Full textAbstract:
Within this thesis are discussed two main topics of contemporary astrophysics. The first is that of machine learning algorithms for astronomy whilst the second is that of magnetic cataclysmic variables (mCVs). To begin, an overview is given of ISINA: INTEGRAL Scouce Identifiction Network Algorithm. This machine learning algorithm, using random forests, is applied to the IBIS/ISGRI data set in order to ease the production of unbiased future soft gamma-ray source catalogues. The feature extraction process on an initial candidate list is described together with feature merging. Three trainng and testing sets are created in order to deal with the diverse time-scales encountered when dealing with the gamma-ray sky: one dealing with faint persistent source recognition, one dealing with strong persistent sources and a final one dealing with transients. For the latter, a new transient detection technique is introduced and described: the transient matrix. Finally the performance of the network is assessed and discussed using the testing set and some illustrative source examples. ISINA is also compared to the more conventional approach of visual inspection. Next mCVs are discussed, and in particular the properties arising from a hard X-ray selected sample which has proven remarkably efficient in detecting intermediate polars and asynchronous polars, two of the rarest type of cataclysmic variables (CVs). This thesis focuses particularly on the link between hard X-ray properties and spin/orbital periods. To this end, a new sample of these objects is constructed by cross-corelating candidate sources detected in INTEGRAL/IBIS observations against catalogues of known CVs. Also included in the analysis are hard X-ray Observations from Swift/BAT and SUZAKU/HXD in order to make the study more complete. It is found that most hard X-ray detected mCVs have Pspin/Porb<0.1 above the period gap. In this respect, attention is given to the very low number of detected systems in any ban between Pspin/Porb = 0.3 and Pspin/Porb = 1 and the apparent peak of the Pspin/Porb distribution at about 0.1. The observational features of the Pspin - Porb plane are discussed in the context of mCV evolution scenarios. Also presented is evidence for correlations between hard X-ray spectral hardness and Pspin, Porb and Pspin/Porb. An attempt to explain the observed correlations is made in th context of mCV evolution and accretion footpring geometrirs on the whit dwarf surface.
24
Rutnakornpituk, Metha. "Synthesis of Silicone Magnetic Fluids for Use in Eye Surgery." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/27723.
Full textAbstract:
Stable suspensions of superparamagnetic cobalt nanoparticles have been prepared in poly(dimethysiloxane) (PDMS) carrier fluids in the presence of poly[dimethylsiloxane-b-(3-cyanopropyl)methylsiloxane-b-dimethylsiloxane] (PDMS-PCPMS-PDMS) triblock copolymers as steric stabilizers. A series of the polysiloxane triblock copolymers with systematically varied molecular weights were prepared via anionic polymerization using LiOH as an initiator. These copolymers formed micelles in toluene or poly(dimethylsiloxane) (PDMS) carrier fluids and served as â nanoreactorsâ for thermal decomposition of the Co2(CO)8 precursor. The nitrile groups on the PCPMS central blocks are thought to coordinate onto the particle surface, while the PDMS endblocks protrude into the reaction medium to provide steric stability. The particle size can be controlled by adjusting the cobalt to copolymer ratio. Ordered self-assemblies of these cobalt nanoparticles are observed when the dispersions are cast from toluene. Electron diffraction spectroscopy reveals that the cobalt nanoparticles have fcc crystal structures. TEM shows non-aggregated cobalt nanoparticles with narrow size distributions, which are evenly surrounded with copolymer sheaths. However, some degree of surface oxidation was observed over time, resulting in a decrease in magnetic susceptibility.
Novel poly[dimethylsiloxane-b-methyltriethoxysilylsiloxane-b-(3-cyanopropyl) methylsiloxane-b-methyltriethoxysilylsiloxane-b-dimethylsiloxane] (PDMS-PMTEOS-PCPMS-PMTEOS-PDMS) pentablock terpolymers were prepared. These terpolymers could fill the dual role both as steric stabilizers for preparing stable cobalt nanoparticle dispersions and
precursors for the particle coating process. Silica films coated on the particles surfaces were employed to prevent the surface oxidation of the nanoparticles. Specific saturation magnetic measurement indicates that coating the nanoparticles with silica thin films can effectively inhibit the oxidation process.Ph. D.
25
Foley, Paul William Xavier. "Cardiovascular magnetic resonance in the prediction of outcome after cardiac resynchronisation therapy." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/2852/.
Full textAbstract:
Contemporary management of patients with heart failure (HF) includes treatment with cardiac resynchronisation therapy (CRT). The benefit of CRT results from several mechanisms, predominantly correction of dyssynchrony. The development of a novel method of measuring left ventricular global dyssynchrony using cardiovascular magnetic resonance (CMR), termed CMR-tissue synchronisation index (CMR-TSI) is described. A study of 225 patients with HF who underwent CMR-TSI found that HF appears synonymous with dyssynchrony. The importance of myocardial scar is illustrated in a study of 95 patients which revealed a significantly higher mortality in patients undergoing CRT who had postero-lateral (PL) scar on CMR. A study into the effects of a combination of CMR-TSI and scar imaging found that presence of either CMR-TSI >110ms or PL scar resulted in a worse outcome, whilst the presence of both was associated with the highest mortality. A final study in 148 patients allowed the development of a risk score to predict mortality from CRT on the basis of 16 candidate variables. PL scar, dyssynchrony and creatine discriminated between survivors and non-survivors and were used to derive the score. The score is discussed in the context of data derived from echocardiography and clinical studies.
26
Drew, Philip. "The clinical application of dynamic magnetic resonance imaging of the breast." Thesis, University of Hull, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322450.
Full text
27
Zaher, Summia S. "Magnetic resonance guided focused ultrasound surgery : a novel treatment for uterine fibroids." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/5948.
Full textAbstract:
Uterine fibroids are the most common tumour of the reproductive tract in women of reproductive age. Although they are benign tumours that are often asymptomatic, they may cause debilitating symptoms in many women, such as abnormal uterine bleeding, abdominal pain, increased abdominal girth, urinary frequency, constipation, pregnancy loss, dyspareunia, and in some cases infertility. Several approaches are available for the treatment of uterine fibroids. These include pharmacologic options, such as hormonal therapies and gonadotropinreleasing hormone agonists; surgical approaches, such as hysterectomy, myomectomy; myolysis, laparoscopic uterine artery occlusion, uterine artery embolisation and magnetic resonance imaging-guided focused ultrasound surgery. The choice of approach may be dictated by factors such as the patient’s desire to become pregnant in the future, the importance of uterine preservation, symptom severity, and tumour characteristics. There is however, no widely agreed therapeutic strategy. There is a widespread view that hysterectomy is overused in the UK; the Chief Medical Officer in his annual report ‘On the state of public health’ in 2005, highlighted that hysterectomy in younger women is associated with complications, hospital stays, procedure-related interference with normal life and is costly. In addition he outlined the need to reduce the number of hysterectomies. This, along with the change in cultural attitudes amongst patients, who are becoming increasingly reluctant to undergo these conventional invasive procedures, has increased the need for new treatment options. Ideally new treatment options for uterine fibroids would be minimally invasive, have long-term data demonstrating efficacy and safety, have minimal or no incidence of fibroid recurrence, be easy to perform, preserve fertility, and be cost effective. New treatment approaches are under investigation, with the goals of being effective, safe, and less invasive. MRgFUS is a non-invasive thermo-ablative hybrid technique which uses both MR and ultrasound to destroy tumours. It is an outpatient procedure, which avoids the need for an anaesthetic, has a short recovery period, and is uterine sparing. The main objective of this work was to set out the rationale for using Magnetic Resonance guided Focused Ultrasound Surgery (MRgFUS) for the treatment of uterine fibroids. In order to achieve this aim, four main bodies of work are necessary; 1) Identifying patient selection criteria and investigating mitigating techniques to increase the pool of women for whom this treatment can be offered. 2) Investigating a method designed to overcome the problem of safely treating women with abdominal scars for whom this treatment can cause potential morbidity. 3) Investigating the potentiality of using MRgFUS to prolong the tumour shrinkage effect of GnRH analogue injections. 4) Investigating the safety of MRgFUS in treating symptomatic women who wish to preserve fertility. Results: the first aim of this project was to identify patient selection criteria and to investigate methods to widen the selection criteria. In our retrospective review it was found that 74% of women presenting were deemed technically suitable to proceed with treatment and several mitigating techniques that solved current technical difficulties were identified and allowed for less restrictive MRgFUS selection criteria for treatment of symptomatic uterine fibroids. These less restrictive criteria are expected to expand the pool of patients for whom MRgFUS is a viable treatment option for uterine fibroid symptoms. The second aim was to identify a method of overcoming the problem of treating women with previous abdominal scars safely. We identified a unique method of highlighting the scar by painting it with a paramagnetic iron oxide material which clearly outlined the scar on MR scanning allowing complete avoidance of the scar using MR guidance. In this small pilot study, all women were treated safely with no skin burns. The third aim of this project looked at the potentiality of prolonging the shrinkage effect of GnRH analogues by following a course of 3 injections with MRgFUS treatment. In this prospective study of fifty women, there was a 50% reduction in the mean symptoms severity score at 6 months which was maintained for 24 months post treatment. There was an average reduction in target fibroid volume which was maintained for 24 months. The final aim of the project was to investigate the safety of using MRgFUS as a treatment option for those women who wished to preserve their fertility. In this multicentre international study, One hundred and sixteen women were recruited from five centres. There were sixty four reported pregnancies in Sixty one women, with 30 completed deliveries. There were no reported cases of uterine rupture, premature labour, abnormal placentation or placental abruption. Conclusion: There is a growing body of data from clinical trials and more than four years of clinical experience to validate the safety and efficacy of MRgFUS for the treatment of uterine fibroids. MRgFUS is a totally non-invasive outpatient procedure that is not associated with the typical surgical risks of bleeding, infection and has minimal recovery time. Additionally, the procedure allows women to address their symptoms whilst preserving the uterus. Consequently, MRgFUS is an alternative treatment option for suitable patients who have refused other interventions due to concerns about lost productivity, risks of surgical complications or future fertility.
28
Martling, Anna. "Rectal cancer : staging, radiotherapy and surgery /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-461-5/.
Full text
29
Naudé, Corus. "Target selection from airborne magnetic and radiometric data in Steinhausen area, Namibia." Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1001520.
Full textAbstract:
The eastern branch of the late Proterozoic Damara Orogenic Belt of central Namibia hosts various copper, gold, manganese and uranium deposits, but in the vicinity of Steinhausen, approximately 145 km northeast of Windhoek, the Damara Belt becomes increasingly covered by recent Kalahari cover sediments resulting in little known geology and subsequent lack of discovered economic mineral deposits. Airborne magnetic and radiometric data over the Steinhausen Study Area was enhanced through image processing and filtering to accentuate characteristics of subsurface geology that, by comparing these characteristics to known geology, aided in the interpretive mapping of lithology, structure and targets for follow-up exploration. As a result, some important observations regarding the regional lithology can be drawn. An arenaceous stratigraphic unit that includes a coarse grained, glassy quartzite below the Kuiseb Formation equates to either the eastern Damaran equivalent of the Nosib Group subjected to high grade metamorphism or, alternatively, the upper part of the pre-Damaran sequence, immediately underlying the Damara. The Kuiseb Formation within the study area is uncharacteristically varied as compared to the same formation further west along the Damaran Orogen and can be subdivided into 5 separate units based on geophysical signature. Structural features evident within the study area include the prominent Kudu and Okahandja Lineaments and straddle an area of inferred uplifted stratigraphy of possibly pre-Damara age. The Ekuja Dome (Kibaran age and host to the Omitiomire copper deposit) is also clearly discernible on the airborne magnetic data and is cross-cut by an east-northeast structural zone. Direct targets for follow-up exploration include the Rodenbeck intrusion, anomalous magnetic bodies and numerous radiometric anomalies present within the study area. Identified dome-like features are considered prospective for Omitiomire-style deposits and the Okatjuru Layered Complex is considered a possible source of copper, chromite, magnetite, ilmenite, nickel and the platinum group elements.
30
Balivada, Sivasai. "A/C magnetic hyperthermia of melanoma mediated by iron(0)/iron oxide core/shell magnetic nanoparticles : a mouse study." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/2282.
Full text
31
Nordman, David. "Forskningsbaserade Tester inom Elektromagnetism : Svenska översättningar av Brief Electricity and Magnetism Assessment (BEMA) och Conceptual Survey of Electricity and Magnetism (CSEM)." Thesis, Uppsala universitet, Fysikundervisningens didaktik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-385753.
Full textAbstract:
Svenska översättningar av Brief Electricity and Magnetism Assessment (BEMA) och Conceptual Survey of Electricity and Magnetism (CSEM) har gjorts. BEMA och CSEM är forskningsbaserade flervalsprov som testar konceptuell förståelse inom elektromagnetism och kan vara utgångspunkt för en fysikundervisning med fokus på konceptuell förståelse på flera nivåer av utbildning. Originalfigurer har använts med en figur modifierad för att förtydliga positionen av en partikel (CSEM uppgift 15). För att motivera översättningarna har det argumenterats för en konceptuell fysikundervisning i kontrast mot en traditionell. Detta gjordes utifrån Skolverket, en rapport ifrån Skolinspektionen och ett flertal publikationer inom Physics Education Research (PER). Speciellt har det argumenterats för en konceptuell fysikundervisning inom elektromagnetism genom att en översikt av de konceptuella utmaningar som området ofta innebär för elever har presenterats. Vid tillfällen har det också givits riktlinjer för hur utbildare kan gå tillväga för att bemöta dessa utmaningar. Utifrån aspekterna svårighetsindex, träffsäkerhet och reliabilitet inom Classic test Theory (CTT) kan BEMA och CSEM anses vara likvärdiga. Den som vill använda BEMA eller CSEM bör därför främst, och kanske också enbart, kolla på vilket av testerna som innehållsmässigt bäst stämmer överens med den aktuella kursen. BEMA och CSEM är innehållsmässigt väldigt lika och har flera uppgifter gemensamma, samtidigt som det finns skillnader, till exempel testar BEMA förståelse för elektriska kretsar medan CSEM inte gör det. Antar vi att BEMA och CSEM är likvärdiga utvärderingsverktyg, och eftersom båda består av ungefär lika många (31 och 32) uppgifter samt enbart flervalsfrågor, kan de användas som för- och eftertest inom samma grupp eller parallellt om två grupper ska testas inom samma kurs. Uppgifter om elektriska kretsar kan då behöva uteslutas ifrån BEMA för en bättre innehållsmässig överensstämmelse mellan proven. CTT är beroende av testgrupp, och eftersom de CTT resultaten som presenteras är baserade på amerikanska collegestudenter kan det vara lämpligt att som utbildare undersöka om BEMA och CSEM även är likvärdiga inom den kontext som de ska användas.Swedish translations of Brief Electricity and Magnetism Assessment (BEMA) and Conceptual Survey of Electricity and Magnetism (CSEM) have been made. BEMA and CSEM are research-based multiple choice tests on conceptual understanding of electromagnetic concepts. They can be used as a starting point for physics teaching with emphasis on conceptual understanding at several levels of education. Figures are from the original tests with one figure modified in order to clarify the position of a particle (CSEM question 15). In order to motivate the translations I make a case for a conceptual approach to physics teaching in contrast to a traditional. This was based on the Swedish National Agency for Education, a publication from the Swedish School Inspectorate and several publications within Physics Education Research (PER). I Specifically make a case for a conceptual approach to physics teaching within electricity and magnetism with an overview of common student difficulties. Occasionally guidelines for how educators can deal with these challenges are given. Based on the aspects difficulty, discrimination and reliability within Classic test Theory (CTT) BEMA and CSEM can be considered equivalent. Those who wish to use BEMA or CSEM should therefore mainly, and perhaps only, decide which test to use based on which test that best matches the course in terms of covered content. Contentwise BEMA and CSEM are very similar and have many questions in common. However, there are differences between them. For example, BEMA tests understanding regarding electric circuits while CSEM does not. If we assume that BEMA and CSEM are equal in quality and combine this with the fact that they are made out of almost the same amount of questions (31 and 32) that are only multiple choice, BEMA and CSEM can potentially be used as pre- and post-tests within the same group or in paralell if two groups are to be tested within the same course. In order to match the two tests in terms of content, electric circuit questions could be omitted from BEMA. CTT results depend on the tested group, and since the CTT results that are presented is based on American college students, further investigation is needed to ensure that they are equivalent also in the Swedish context.
32
Webb, Jocasta Anne. "Magnetic resonance image analysis techniques for quantification of hippocampal integrity in temporal lobe epilepsy." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367210.
Full text
33
Xie, Hui. "Magnetic resonance compatible tactile force sensing using optical fibres for minimally invasive surgery." Thesis, King's College London (University of London), 2015. http://kclpure.kcl.ac.uk/portal/en/theses/magnetic-resonance-compatible-tactile-force-sensing-using-optical-fibres-for-minimally-invasive-surgery(19b33b9c-81ae-4dd5-87a5-a0542019ad43).html.
Full textAbstract:
This thesis presents research in design, fabrication and testing of magnetic resonance (MR) compatible tactile array sensors based on light intensity modulation using optical fibres. The popularity of minimally invasive surgery (MIS) opens the field of tac-tile sensing for medical use, especially in MR environment. The departure from con-ventional sensing approaches (such as capacitive and piezoresistive) allows the devel-opment of tactile sensors which are low cost, small in size, lightweight, free from electromagnetic interference, water and corrosion resistant and capable to operate in harsh environments. In the framework of this PhD study, a number of MR compatible tactile array sensors have been developed, including uniaxial tactile array sensors and an x- and y-axis lateral contact sensor. Mathematical models for these newly-devel-oped tactile sensors have been created and verified. Force is measured through the displacement of a flexible structure with a known stiffness, modulating in turn the light intensity in the employed optical fibres. For the tactile array sensor, a 2D vision system is applied to detect light signals from all sensing elements via the optical fibres – this new approach provides a great potential for high density tactile array sensing, employing a low-cost vision sensor. For the lateral sensor, high-speed/high-sensitivity detectors are utilized to calculate contact force position and magnitude. Combined with 3D printing technology, a miniature tactile probe head capable of palpation in MIS has been designed and tested in ex vivo tissue palpation experiments. All sensor systems developed in this thesis are MR compatible and immune to electromagnetic noise. The proposed sensing structures and principles show high miniaturization and resolution capabilities, making them suitable for integration with medical tools.
34
Lin, Nancy Y. "Applications of Hyperpolarized 129-Xenon Magnetic Resonance Imaging in Pediatric Asthma." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1593268100652155.
Full text
35
Antel, Samson. "Computational analysis of magnetic resonance data assista in pre-surgical evaluation of epilepsy patients." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82820.
Full textAbstract:
This dissertation presents a series of studies aimed at applying machine learning methods to information derived from magnetic resonance (MR) based examinations in order to aid in the pre-surgical evaluation of patients with epilepsy. Two forms of epilepsy were studied: non-lesional temporal lobe epilepsy (TLE) and extra-temporal lobe epilepsy (ETLE) due to malformations of cortical development (MCD).Regarding patients with TLE, our aim was to predict outcome, in terms of reduction of seizure frequency, following surgical resection. To this end, we trained a Bayesian classifier on results from volumetric magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI), which allow rapid, non-invasive measurement of structural and metabolic data, respectively. We demonstrated that the pattern of MR markers can predict whether or not a patient with TLE will benefit from surgery.
In our studies of patients with ETLE, we focused on patients whose epilepsy was due to focal cortical dysplasia (FCD), a common form of MCD. In these patients, the identification of FCD lesions is critical in helping to direct the site of surgical resection. This is commonly performed by visual analysis of conventional MRI. The MRI characteristics of FCD are well known; however, in many patients, lesions of FCD are characterized by minor structural abnormalities that go unrecognized or are too subtle to be detected by standard radiological analysis. Thus, the objective of this part of the dissertation was to use mathematical models of the MRI characteristics of FCD as a basis for automated detection of FCD lesions. The mathematical models included first-order statistical and morphological operators which can help measure visually discernable MRI characteristics of FCD lesions, and second-order texture analysis, which can quantify information regarding tissue structure or organization not readily accessible through visual analysis. A Bayesian classifier trained on these models demonstrated a significantly increased sensitivity in lesion detection compared to standard analysis of conventional MRI.
Both components of this thesis present clinically useful techniques for applying machine learning methods to MR data to assist in the pre-surgical evaluation of epilepsy patients. These methods are intended to be used in conjunction with conventional approaches.
36
Darkazanli, Ammar. "Magnetic resonance imaging modeling and applications to fast imaging and guidance of ultrasound surgery." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186252.
Full textAbstract:
Magnetic Resonance Imaging (MRI) is the only known radiological modality that provides a diagnostic cross sectional images non-invasively in virtually any orientation without patient repositioning. The principles of MRI are based on Bloch's equations, which describe the behavior of proton molecules in the presence of a magnetic field. There are many interesting areas where MRI has contributed, such as perfusion and diffusion studies, MR angiography, cardiac studies as weIl as therapeutic applications in cancer treatment. In this dissertation two MRI related topics were investigated. First, a computer program was developed to simulate virtually any MRI pulse sequence. The phase encoding gradient pulses are also included which has proved to be very useful in predicting image artifacts and contrast behavior. The second is the application of MRI in guiding ultrasound surgery. A detailed study was performed on the sensitivity of MRI parameters to temperature changes. In-vivo studies were also performed on seven Greyhound dogs and twenty five rabbits. Temperature elevations were successfully depicted using MRI. Computer simulations were also used to study the effects of changing temperature during image acquisition.
37
Shin, Minchul. "MRI evaluation of a stented abdominal aorta of a rabbit /." Birmingham, Ala. : University of Alabama at Birmingham, 2007. https://www.mhsl.uab.edu/dt/2009r/shin.pdf.
Full textAbstract:
Thesis (M.S.)--University of Alabama at Birmingham, 2007.Title from PDF of title page (viewed October 13, 2009). Additional advisors: Brigitta C. Brott, Jack E. Lemons, Steven G. Lloyd. Includes bibliographical references (p. 28-31).
38
Chivers, David Andrew. "Long term follow up of rotator cuff Magnetic resonance imaging changes in patients who underwent acromioplasty without repair of full thickness supraspinatus tendon tears." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16535.
Full textAbstract:
Includes bibliographical referencesAim: To assess the MRI pathoanatomical changes 10 years after unrepaired full thickness supraspinatus tears in a population of patients that had acromioplasty done for symptomatic impingement with a rotator cuff tear.
39
Eley, Karen A. "Imaging the craniofacial skeleton : is MRI a viable alternative to ionising radiation?" Thesis, University of Oxford, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.711645.
Full text
40
Samaha, Mark. "Functional magnetic resonance imaging (fMRI) of the auditory cortex : an event-related study using pure tone stimulation." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33028.
Full textAbstract:
Introduction. The use of Functional Magnetic Resonance Imaging (fMRI) in studying central auditory pathways expanded our knowledge of the neurophysiology of hearing. In various studies, an array of diverse auditory stimuli has been used, including pure tones and words, in a "Block" design. Few studies, thus far, have been performed using an event-related design. None of these has used pure tone stimulation.Subjects and methods. In eight out of 13 subjects enrolled and scanned in this project, data have been acquired and processed. Binaural pure tone stimulation at 2kHz and one higher frequency at 6, 8, or 12 kHz, at 90 dB SPL was presented to all subjects, using a stroboscopic design in an attempt to eliminate cortical response to scanning noise. In addition, an unusually long time of repetition (TR) interval of 10 seconds was utilized. The aim in data processing was to generate: (a) a Peak Height Map (PHM) with selection of areas of stimulation based on the maximal response; (b) a statistical map from the raw data of the images.
Results. No consistent morphology was detected in the BOLD event-related curves, corresponding to the percentage change from baseline over time. Such curves revealed significant oscillation with marked dips below baseline, highly suggestive of an irregular noise pattern. Comparing the curves to each other, no discernible shape or similarities were noted.
Conclusion. Attempting to extract both the temporal and spatial characteristics of the cortical response to pure tone stimuli resulted in a dispersal of data over many parameters, therefore "diluting" it. This, in turn, yielded a negative result where the responses were "drowned" revealing but a noise pattern.
41
Jorstig, Stina. "On the assessment of right ventricular function using cardiac magnetic resonance imaging and echocardiography." Doctoral thesis, Örebro universitet, Institutionen för medicinska vetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-51662.
Full textAbstract:
Transthoracic echocardiography (TTE) and cardiac magnetic resonance (CMR) imaging are two commonly used imaging modalities for evaluating the size and function of the heart. There are advantages and disadvantages associated with both modalities when examining the right ventricle (RV). The RV is positioned partly behind the sternum and lung, sometimes causing shadows in the TTE images. This along with the complex shape of the RV makes volume calculations challenging by 2D TTE. CMR is considered to be the reference method for volume calculations of the ventricles. The valve separating the RV from the right atrium is however often oblique compared to the valve separating the left ventricle from the left atrium. This complicates RV volume calculations using conventional CMR short-axis stack images. The aim of this thesis was to find ways to improve the RV stroke volume and ejection fraction calculations using TTE and CMR. A method, transferring the position of the tricuspid plane from RV long-axis images to short-axis images, was developed to improve the separation of the right atrium from the RV when calculating RV stroke volumes by CMR. The method provided calculations of RV stroke volumes with good agreement to reference volumes. Further, the movements contributing to the RV stroke volume was studied aiming to find new ways of calculating RV stroke volumes and ejection fraction by TTE. A model for RV stroke volume and ejection fraction calculations was evaluated showing underestimation of stroke volumes by TTE compared to CMR, which probably depend on differences in distance measurements using the two modalities. The model provided, however, promising results for ejection fraction calculations which was validated in a study of 37 participants that covered a wide range of EF.
42
Kelley, Joshua Jed. "Maintaining Skeletal Muscle Through Eccentric Exercise after Bariatric Surgery: A Randomized Controlled Trial." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7742.
Full textAbstract:
Purpose: To investigate the effects of eccentric exercise on lower body skeletal muscle mass during rapid body mass loss induced by bariatric surgery. Methods: All participants began 6 to 8 weeks after undergoing Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG). Skeletal muscle mass (SMM) in the lower body was measured via magnetic resonance imaging (MRI); additional exercise measurements included muscular strength and functional capacity. Quality of life was measured using Short Form 36 (SF-36). Nineteen females (age = 37.6 ± 9.8 yr, height = 164.4 ± 7.2 cm, mass = 106.9 ± 15.6 kg) were randomly assigned to 1 of 3 groups: eccentric exercise (EEX; n = 6), concentric exercise (CEX; n = 7), or standard-of-care control (CON; n = 6). Exercise groups performed 30-minute lower-body exercise sessions 3 times per week for 16 weeks. Each month the exercise tests were evaluated. At the end of 16 weeks, all participants performed the final exercise tests, received a final MRI scan, and completed the SF-36 questionnaire. Results: Thirteen individuals completed the study. All groups lost mass: CON: 21.4 ± 3.7 kg (p < 0.001), CEX: 19.9 ± 4.0 kg (p = 0.001), and EEX: 21.8 ± 3.3 kg (p < 0.001). SMM decreased in all groups: CON: 0.77 ± 0.5 kg (p = 0.18), CEX: 1.19 ± 0.6 kg (p = 0.06), and EEX: 0.90 ± 0.5 kg (p = 0.09). The skeletal muscle loss in percent of total mass loss was 3.7 ± 4.1%. All measures of muscular strength showed no difference, except for a small decrease in dynamic (60°·sec-1) strength in the eccentric group. Functional capacity and physical quality of life increased significantly in all groups (p < 0.05). Conclusion: SMM loss still occurred in the lower body regardless of resistance training, but the loss was less than what was previously documented. Improved postsurgical functional capacity and physical quality of life may be due to a reduction in fat mass and maintenance of muscular strength during the period of rapid mass loss.
43
Wavreille, Vincent Alain. "Correlation Between Histopathologic, Arthroscopic and Magnetic Resonance Imaging Findings in Dogs with Medial Coronoid Disease." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397060501.
Full text
44
Steuer, Johnny. "Perioperative Myocardial Damage and Morbidity after Coronary Artery Bypass Grafting." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4199.
Full text
45
Karolyi, Daniel Roberts. "Hemodynamic wall shear stress in models of atherosclerotic plaques using phase contrast magnetic resonance velocimetry and computational fluid dynamics." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/20132.
Full text
46
Khan, Muhammad Faisal. "Non-rigid image registration for deep brain stimulation surgery." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26546.
Full textAbstract:
Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.Committee Chair: Oskar krinjar; Committee Member: Allen Tannenbaum; Committee Member: Anthony Yezzi; Committee Member: John Oshinski; Committee Member: Patricio Vela. Part of the SMARTech Electronic Thesis and Dissertation Collection.
47
Rosenstock, Tizian [Verfasser]. "Risk stratification in motor area-related glioma surgery based on navigated transcranial magnetic stimulation data / Tizian Rosenstock." Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2018. http://d-nb.info/1153768631/34.
Full text
48
Tandon, Animesh. "Dystrophin genotype-cardiac phenotype correlations in Duchenne and Becker muscular dystrophy using cardiac magnetic resonance imaging." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1396453528.
Full text
49
Jose, Arun. "Value of Baseline Cardiac Magnetic Resonance Imaging for Predicting Adverse Outcomes in Treatment-naive Pulmonary Hypertension Patients." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1560866307524617.
Full text
50
Romagnuolo, Joseph. "Magnetic resonance cholangiopancreatography (MRCP) versus endoscopic retrograde cholangiopancreatography (ERCP) for the management of patients with suspected biliary obstruction : an interim analysis of a randomized effectiveness trial." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33026.
Full textAbstract:
Background. Up to 1600 Canadians/yr suffer a serious complication due to the diagnostic test ERCP (endoscopic retrograde cholangiopancreatography) used in the management of patients with suspected biliary obstruction. MRCP (magnetic resonance cholangiopancreatography) is a new highly accurate noninvasive alternative that is not associated with any significant complications.Aims. To assess the real-life effectiveness and costs of MRCP versus ERCP in a planned interim analysis of a randomized clinical trial, in intermediate risk patients. To assist in the decision regarding study continuation versus termination.
Methods. 200 patients with a clinical and/or ultrasonographic (US) suspicion of obstruction were randomized to MRCP or ERCP, using block allocation stratified by level of obstruction. The primary endpoint was the occurrence of a negative outcome attributable to the biliopancreatic disease or procedures within 12 months of randomization. Secondary outcomes included complication-related length of stay (CRLOS), number of procedures, costs, mortality and accuracy.
Results. 102 patients were randomized to MRCP and 98 to ERCP with mean ages of 56.4 +/- 18 (SD) and 51.8 +/- 19 yrs, respectively. Median follow-up was 12 months. According to intention-to-treat analysis, 18 (17.6%) MRCP patients had a complication (CRLOS = 0.80 d/patient (excluding 1 outlier with CRLOS = 157d) versus 14 (14.3%) ERCP patients (CRLOS = 0.68d/patient); difference = 3.3% (95%CI: -7 to 13%). There were 45 fewer ERCPs but 90 extra MRCPs in the MRCP arm. ERCP was "dominant", with both marginally lower complications and lower costs by $1411/person (ITT). There was neither evidence for confounding nor effect modification.
Conclusions. In this interim analysis, it appears that a strategy that involves a screening MRCP in this group of patients is not cost-effective. The results of this primary analysis are unlikely to change with the recruitment of 200 additional patients into the trial.