Sökning: "Phantom model"

Visar resultat 1 - 5 av 58 avhandlingar innehållade orden Phantom model.

1. 1. Risk from radionuclides: a frog's perspective : Accumulation of 137Cs in a riparian wetland, radiation doses, and effects on frogs and toads after low-dose rate exposure

   Författare :Karolina Stark; Nils Kautsky; Petra Wallberg; Torbjörn Nylén; Michael Gilek; Dennis Woodhead; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; dose model; mass balance budget; overbank sedimentation; amphibian; phantom; thermoluminescence chip; radiosensitivity; DNA damage; Biology; Biologi;

   Sammanfattning : Threats from man-made radionuclides include waste issues, increasing number of power plants, underground bomb testing, nuclear weapons, and “dirty bombs”. Until recently the ionizing radiation protection system focused on protecting humans with an implied protection of biota. LÄS MER

3. 2. Detecting Inclusions in a Silicone Rubber Phantom Using Standing Lamb Waves and Multiple Frequency Footprints

   Författare :Ulf G Jonsson; Britt Andersson; Olof A Lindahl; Jacques Ohayon; Umeå universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Piezoelectric; Silicone rubber; Impedance; Resonance; Lamb waves; Phantom; Electronics; elektronik;

   Sammanfattning : The thesis deals with one major question: is it possible, using one piezoelectric sensor/vibrator, to detect a hard inclusion in a silicone rubber phantom? The question was approached with an open mind and the task was subdivided into three clearly identifiable parts: characterization of the piezoelectric sensor/vibrator (paper I), creating a model of the visco-elastic properties of a tissue-like material (phantom) in contact with the sensor/vibrator (paper II), and to detect the presence of a hard inclusion in the phantom (paper III). All vibrations of the sensor/vibrator and phantom was modeled using a finite element method (FEM). LÄS MER

4. 3. Phantom of the Neighbourhood : Longitudinal Studies on Area-based Conditions and Individual Outcomes

   Författare :Lars Brännström; Sten-Åke Stenberg; Tomas Korpi; Björn Halleröd; Stockholms universitet; []
   Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Neighbourhood effects; Contextual effects; Residential segregation; Sweden; Sociology; Sociologi;

   Sammanfattning : This dissertation consists of three self-contained but interrelated empirical studies focusing on theoretical, empirical and political questions in the multidisciplinary field of neighbourhood effect research. Along with a comprehensive introductory essay, each study addresses questions concerning the potential influence of neighbourhood characteristics on individual social and economic outcomes at different life stages. LÄS MER

5. 4. Ultrasonic Methods for Quantitative Carotid Plaque Characterization

   Författare :Erik Widman; Matilda Larsson; Mark L. Palmeri; KTH; Karolinska Institutet; Karolinska Institutet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Atherosclerosis; Cardiovascular Disease; Carotid Artery; Elasticity; ex vivo; in vivo; Phantom; Plaque; Polyvinyl Alcohol; Pulse Wave Imaging; Shear Wave Elastography; Speckle Tracking; Stroke; Ultrasound; Medical Technology; Medicinsk teknologi; Atherosclerosis;

   Sammanfattning : Cardiovascular diseases are the leading causes of death worldwide and improved diagnostic methods are needed for early intervention and to select the most suitable treatment for patients. Currently, carotid artery plaque vulnerability is typically determined by visually assessing ultrasound B-mode images, which is influenced by user-subjectivity. LÄS MER

7. 5. Toward increased applicability of ultrasound contrast agents

   Författare :Malin Larsson; Lars-Åke Brodin; Anna Bjällmark; Kenneth Caidahl; Jan Engvall; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Contrast agent; Contrast-to-tissue-ratio; Echocardiography; Endocardial border; Microbubbles; Multimodal; Phantom; Polymer; Ultrasound; Wall motion score index.; Teknik och hälsa; Technology and Health;

   Sammanfattning : Ultrasound is one of the most widely used modalities in medical imaging because of its high cost-effectiveness, wide availability in hospitals, generation of real-time images, and use of nonionizing radiation. However, the image quality can be insufficient in some patients. LÄS MER