Gliomas constitute 36% of all primary brain tumors and 81% of all primary malignant brain tumors. The overall prognosis in patients with gliomas depends mainly on the location and histologic grade of the tumor.<p>The World Health Organization classification of gliomas is the primary basis for guiding therapy and assessing overall prognosis in gliomas. This classification system, based on histological features, often falls short of predicting therapeutic response of individual tumors within the same histological grade. Yet, it still remains the grading method for both research and clinical prospects.<p>Unlike any other organ the brain has multiple protective layers such as the skull that ensure a homeostatic environment. The resulting reduced access to the brain and the absence of plasmatic brain tumor markers bring neuroimaging in a central position in diagnosis and management of brain tumors. Moreover, neuroimaging has evolved from a purely morphologic investigation into a diagnostic tool that allows characterization of particular physical alterations within brain tissue. Understanding the relationship between the physical characteristics of tumor tissue, studied by MR imaging, and biological characteristics of the tumor is therefore important for the appropriate integration of neuroimaging in brain tumor management. The general objective of this work is to define the relationship between physiologybased MR imaging and biological features of glial tumors. Diffusion and perfusionweighted imaging, physiologybased MR techniques provide the data based on physical characteristics of the tissues. Diffusion weighted imaging (DWI) allows the measurement of water molecules diffusivity within the brain tissue by means of apparent diffusion coefficient (ADC) measurements. Perfusion weighted imaging (PWI) is based on changes of MR signal during the passage of contrast material through the intravascular space and allows hemodynamic measurements such as those of cerebral blood volume (CBV)within the brain tissue.<p>Highgrade diffuse gliomas are currently differentiated from low grade diffuse gliomas by increased cellularity with nuclear atypia, mitotic activity, endothelial proliferation and necrosis. Components of the extracellular matrix and angiogenesis constitute some other features of gliomas, which have established links with oncogenic processes that influence the proliferative and infiltrative potentials of these tumors. We have specifically targeted these features in our comparative studies with the working hypothesis that physiologybased MR measurements, obtained in vivo, might provide information that is pertinent in terms of tumor malignancy.<p>We chose to approach the biology of brain tumors in two ways: in vivo, by means of metabolic imaging techniques such as positron emission tomography (PET) and ex vivo, by means of histological and immunohistochemical analyses of tumor specimens.<p>Many studies have investigated the relation between ADC values and cellularity in gliomas. The underlining theory is based on the premise that water diffusivity within the 9 extracellular compartment is inversely related to the content and attenuation of the constituents of the intracellular space. Therefore when cellularity increases, intracellular space volume increases with a relative reduction of the extracellular space, leading to restricted diffusion of water molecules. However other factors may affect the value of ADC in gliomas such as the extracellular matrix which contains various amounts of hydrophilic macromolecules susceptible to change water molecules diffusivity. Hyaluronic acid is one highly hydrophilic component of the extracellular matrix of gliomas and its level of expression changes significantly during the progression to anaplasia in gliomas. Our hypothesis was that hyaluronan may influence ADC values in high and low grade gliomas.<p>We demonstrated a positive correlation between ADC values and the immunohistochemical level of hyaluronan in glial tumors.<p>Previous studies have confirmed the utility of positron emission tomography using C11 Methionine (PETMET) as a prognostic tool in patients with gliomas. Higher MET uptake is associated with greater proliferative potential and a higher level of malignancy in gliomas.<p>The increased aminoacid uptake in gliomas seems to reflect increased transport mediated by aminoacid carriers located in the endothelial cell membrane. Our hypothesis was that CBV measurements, index of tumor vascularity, may be related to tumor aminoacid metabolism.<p>We found a positive correlation between maximum CBV values and maximum MET uptake values in gliomas.<p>A limitation to these preliminary studies was lack of direct correlation between MRbased measurements and histologic and metabolic data. Indeed, glial tumors are known for their remarkable tissue heterogeneity across different grades, within the same grade, and even within a single given tumor. Therefore we used image coregistration and stereotactic biopsies to further assess the relationship between MRbased imaging data and both metabolic and histologic analysis.<p>The second part of our studies was based on measurements at the exact same localization on both MR and PET images where biopsy specimens were performed. We found a local relationship between CBV and MET uptake values. Both measurements correlated with mitotic activity and endothelial proliferation; two features of tumor aggressiveness.<p>In order to quantify tumor cellularity and tumor angiogenesis, we respectively measured cell density and vessel density using immunohistochemical markers to identify vessels. We found a regional relationship between CBV and cell density, as well as vessel density in gliomas whereas no correlation was found regionally between ADC and cell density.<p>We concluded that CBV measurements may be used locally as indices of angiogenesis and cellularity in gliomas; whereas local ADC measurements are more variable and may not be used as a marker of cellularity in heterogeneous tumors such as gliomas. / Doctorat en Sciences médicales / info:eu-repo/semantics/nonPublished

Acute appendicitis is a common cause of abdominal surgery in children, and is the result of appendiceal luminal obstruction and subsequent inflammation. The clinical presentation is often variable, allowing imaging to play a central role in disease identification and characterization. Ultrasound is often the modality of choice for diagnosis of appendicitis in children. Ready availability and lack of ionizing radiation are attractive features of sonography, though operator dependence is a potential barrier. Computed tomography (CT) was historically the preferred modality in children, as in adults, but recent awareness of the risks of radiation has reduced its usage. The purpose of this article is to detail the imaging findings of appendicitis in children. The discussion will focus on typical signs of appendicitis seen on ultrasound, CT, and magnetic resonance imaging. Considerations for percutaneous drainage by interventional radiology will also be presented. Finally, the evolution of imaging algorithms for appendicitis will be discussed.

Immobilisation has been one of the common forms of treatments for orthopaedic injuries and diseases. Immobilisation of injured limbs using dynamic splinting is routinely recommended by clinicians for fast healing as it promotes blood flow and provides the require stability. There are several dynamic splints available in the market that make use of different materials and mechanical elements. This research was set out to investigate the applicability of Magneto-Rheological(MR) fluids for the development of a smart fabric for orthopaedic splints. The fabric would be woven with hollow fibres containing MR fluid, which will change stiffness in an applied magnetic field. The concept was tested by measuring changes in the stiffness of silicone tubings in two different diameters filled with MR fluid, under different magnetic flux densities. The corresponding changes in stiffness of a preliminary fabric specimen built with woven tubings and cast liner was also investigated. The magnetic field was created after a set of detailed experimental and numerical analyses (Finite Element Method). It was found that although the electromagnets are much more versatile and easier to control for a required magnitude of magnetic flux density, they were found to be unsatisfactory due to their weight, bulk, and substantial requirement of batterie power. Permanent magnets offered a much better solution. After detailed preliminary analyses, an array of 21 neodymium magnets was chose for the experiments, which provided the required magnitude and uniformity of the magnetic field. The specimens were loaded in steps by small weights, and the resulting deflection was measured using an optical deformation analysis system. The equivalent Young’s modulus was found to increase from 16 MPa to 122 MPa under an average magnetic flux density of 0.0139 Tesla, which is an in- crease of 70%. A finite-element (FE) model of the single tubing test set up was developed and validated against the experimental results. The FE analysis was extended to the fabric specimens. The difference between the experimental and numerical results for the single tubing was as small as 2.5%, and 9.2% for the fabric. Furthermore, a preliminary numerical model and analysis of the hand was developed, which set the basis in the development of a further numerical analysis in the final development of the fabric. Upon the completion of the tests and simulation, it was concluded that a woven fabric made up of hollow fibres containing MR fluid can be an effective dynamic splint over a small area such as the wrist. However a fully functional product would require further research.

Proton MR spectroscopy is a non-invasive tool for measuring in vivo concentrations of several metabolites. The aim of this thesis was to test its applicability and reliability in neurosurgical praxis. In the first part of the study multiple MR spectroscopy methods were applied in a group of patients after surgery and oncologic treatment for high-grade glioma to test which method performed best in discriminating recurrent tumor from radionecrosis in the presence of a new enhancing lesion. The best diagnostic yield was achieved by comparison of choline, creatine and lactate between lesion and contralateral side (sensitivity 93.3%, specificity 78.6%). Creatine was significantly decreased in patients compared to controls. The inhibiting effect of ongoing oncologic treatment on cerebral and tumoral metabolism makes differential diagnosis trickier. Therefore, a diagnosis of radionecrosis assessed during ongoing radio- and chemotherapy should be confirmed after its completion. In the second part of the study MR spectroscopy data was compared with MR hippocampal volumetry and transcranial doppler examination in a cohort of patients with unilateral occlusion of the internal carotid artery. The N-acetylaspartate/choline ratio and hippocampal volume were significantly lower in both hemispheres of patients...

While literary critics acknowledge the amoral and criminal behavior of Thomas Ripley, the antihero in Patricia Highsmith’s Ripliad series, many critics fail to recognize Highsmith’s parables in connection to ethical responsibility to the Other and guilt because of falling into complete despair. By examining Ripley’s character through an ethical lens, I contend that Ripley’s inability to connect with others disallows him from engaging in moral behavior that would establish basic responsibility for others. This results in a repetitive cycle of criminality that leads to inner turmoil and a sickness of the spirit. This thesis analyzes the parables in Highsmith’s novels by applying Emmanuel Levinas’s ethics in relation with Soren Kierkegaard’s conception of human existence. Ripley lives a lonely existence because he is unaware of his ethical dilemma, covets wealth at all costs, and fails to recognize that his division from society is at the root of his infinite despair. / Includes bibliography. / Thesis (MA)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

This thesis deals with the removal of noise in speech recordings that have been recorded in an MRI environment. For this purpose, the Nvidia RTX Voice technology, the VST plug-in module Noisereduce and a self-designed method of subtractive de-noising of recordings are used. A program with a simple graphical interface in Python is implemented within the work to retrieve the recordings and then de-noise them using the proposed methods. The work includes measurements in a magnetic resonance environment with two microphones. The quality of the processed recordings is tested within the program using the STOI (Short-Time Objective Intelligibility Measure) method as well as the subjective analysis method within listening tests.

This thesis deals with the design of the magnetorheological (MR) clutch. The extensive literature research with particular conclusions to each design variant of MR clutches or brakes has been done in the first part of the thesis. The second part of the thesis describes the design of the actual MR clutch based on the results of the analytical calculation of the magnetic circuit. Finally, the experiments verifying the function of the key segments of the clutch, and the whole clutch are summarized in the third part of the thesis.

Quantum chemical methods have been used to model a variety of p- and f-block chemical species to gain insight about their energetic and spectroscopic properties. As well, the studies have provided understanding about the utility of the quantum mechanical approaches employed for the third-row and lanthanide species. The multireference ab initio correlation consistent Composite Approach (MR-ccCA) was utilized to predict dissociation energies for main group third-row molecular species, achieving energies within 1 kcal mol-1 on average from those of experiment and providing the first demonstration of the utility of MR-ccCA for third-row species. Multireference perturbation theory was utilized to calculate the electronic states and dissociation energies of NdF2+, providing a good model of the Nd-F bond in NdF3 from an electronic standpoint. In further work, the states and energies of NdF+ were determined using an equation of motion coupled cluster approach and the similarities for both NdF2+ and NdF were noted. Finally, time-dependent density functional theory and the static exchange approximation for Hartree-Fock in conjunction with a fully relativistic framework were used to calculate the L3 ionization energies and electronic excitation spectra as a means of characterizing uranyl (UO22+) and the isoelectronic compounds NUO+ and UN2.

Bakgrund: Värmepåverkan vid magnetkameraundersökningar är ett känt fenomen som påverkar patienterna och temperaturmätningar kan vara missvisande. Antalet undersökningar ökar, fler patienter med och utan implantat kommer för diagnostisering, detta kräver att personalen har bra rutiner och kunskap för att förhindra brännskador. Syftet: Syftet med studien var att beskriva faktorer som påverkar uppvärmning av patienten vid magnetkameraundersökningar. Metod: Studien har genomförts som en allmän litteraturöversikt där elva artiklar inkluderats. Resultat: Tre kategorier har identifierats: tekniska aspekter, riskgrupper och bristande rutiner. Resultatet visar att det totala SAR-värdet inte är tillförlitligt vilket kan öka risken för lokala brännskador, i synnerhet för riskgrupper som har ökad risk för uppvärmning. I händelse av att röntgensjuksköterskan inte väljer rätt anpassat protokoll vid en undersökning finns det risk för ökad uppvärmning samt att positioneringar av patient, spole och kablar är viktigt för att förhindra brännskador. Ett bra teamarbete, kommunikation och kunskap om uppvärmning vid magnetkameraundersökningar leder till ökad patientsäkerhet. Slutsats: Studiens resultat visar att uppvärmningen har en stor betydelse på magnetkameraundersökningar och att adekvat mätutrustning ska användas. Uppvärmningen kan minskas genom olika omvårdnadsåtgärder som kan vara att inte bädda in patienten samt öka styrkan på fläktar i magnetkameran.

Mixed Reality(MR) tillåter en visuell representation av virtuella objekt i det mänskliga synfältet. Genom att visualisera virtuella objekt kan befintliga arbetsmetoder förenklas och även utvidgas med saker som annars inte vart möjligt. Examensarbetet kommer att titta på hur Mixed Reality kan tillämpas för en arbetsorder, där man med Mixed Reality visualiserar en arbetsorders position baserat på sfäriska koordinater. Examensarbetet kommer även att titta på hur ett befintligt arbetsflöde för en arbetsorder kan representeras och interageras med.För att uppnå detta behövs det särskilt utredas om hur man relativt en given position för arbetsorder tar fram en position för användaren och placerar ut objektet relativt användaren och arbetsordern.Särskilt måste även interaktionsmöjligheter undersökas där en arbetsorder skall presenteras för en användare, och även ge användaren möjlighet att uppdatera arbetsorderns status. För att uppnå ett mätbart resultat så tas en applikation fram för en HoloLens 2-enhet, där de metoder som implementeras demonstrerar om målen har uppnåtts.Applikationen skapas i Unity med hjälp av Mixed Reality ToolKit.Applikationen i HoloLensen inhämtar positionsdata från en Android-klient då HoloLensen saknar möjlighet att inhämta positionsdata baserat på sfäriska koordinater.En modul som läser in QR-koder för att skapa en ankarpunkt tillämpades, där ankarpunkten sedan används för att placera ut och spara markörobjekt relativt ankarpunktens position.En checklista tas fram för att visa på hur statusrapportering kan utföras i Mixed Reality utan att kräva textinmatning. Resultatet visar på att det är fullt möjligt att inhämta GPS-data till en HoloLens och rita ut objekt baserat på dess koordinat relativt användaren.Lämpligheten att enbart använda GPS-data för positionering anses inte lämpligt om målet är att representera arbetsorderns position mer utförligt än en grov uppskattning, och en metod bestående av GPS-data och Azure Spatial Anchors föreslås för en mer precis positionering.Resulterande applikation visar även på att man med HoloLens kan visa en arbetsorder och dess innehåll samtidigt som man med en checklista för arbetsordern markerar delmoment som utförda och på så sätt skapar ett exempel på ett arbetsflöde utan tidskrävande inmatningar. En meny för markörer tas fram som visar att det är möjligt att med hög precision markera objekt relativt arbetsorderns QR-kod. / Mixed Reality (MR) allows a visual representation of virtual objects in the human field of vision. By visualizing virtual objects, existing working methods can be simplified and even expanded with methods that would not otherwise be possible. The project will look at how Mixed Reality can be applied to a work order, where Mixed Reality visualizes the position of a work order based on cartesian coordinates. The project will also look at how an existing workflow for a work order can be represented and interacted with.To achieve this, it is necessary to investigate in particular how to receive the position for an user relative to a given position for a work order, and place the object relative to the user and the work order.In particular, the possibilities to interact must also be investigated. A user should be able to read a work order, and also have the ability to update the status of the work order. To achieve a measurable result, an application is developed for a HoloLens 2-device, where the methods selected to be implemented demonstrate if the goals have been achieved.The application is created in Unity using the Mixed Reality ToolKit.The application in HoloLensen gets position data from an Android client as the HoloLensen does not have the ability to collect position data based on cartesian coordinates.A module that reads QR codes to create an anchor point is also applied, where the anchor point is then used to place and save marker objects relative to the position of the anchor point.A checklist is created to show how status of the work order can be updated in Mixed Reality without requiring text input. The results show that it is possible to obtain GPS data for a HoloLens and visualize objects based on its coordinates relative to the user.The suitability to use only GPS data for positioning is not considered appropriate if the goal is to represent the position of the work order in more detailed manner than a rough estimate, and a method consisting of GPS data and Azure Spatial Anchors is proposed for a more precise positioning.The resulting application also shows that the HoloLens can display a work order and its content. By using a checklist to mark steps as completed, its possible to create a work flow without requiering time-consuming inputs. A menu for markers is also produced which shows that it is possible to mark objects with high precision relative to the QR code of the work order.