28 research outputs found
Local Coils and Prospective Shimming for MRI of the Spinal Cord
No full textRÉSUMÉ: Plus de 85,000 de canadiens sont victimes des pathologies de la moelle épinière dont les effets peuvent impliquer des difficultés motrices, sensorielles, et fonctionnelles. Le développement de biomarqueurs quantitatifs pourrait permettre les médecins de mieux prédire les résultats de traitements médicaux pour les pathologies de la moelle épinière afin de mieux les adapter aux patients individuels. À cet effet, l'imagerie par résonance magnétique (IRM) pourrait servir grâce à sa capacité unique à générer plusieurs contrastes d'images qui, en fonction des paramètres d'acquisition, peuvent être adaptés afin de refléter diverses propriétés tissulaires et processus physiologiques. La moelle épinière présente un défi pour les techniques l'IRM avancées. Au sein de son environnent anatomique, la susceptibilité magnétique est très hétérogène, ce qui conduit à des variations importantes du champ magnétique (B0) dans la moelle épinière elle-même. Ceux-ci entraînent fréquemment une variété d'artefacts d'image tels que la perte de signal et la distorsion géométrique. De plus, en raison de sa proximité aux poumons, la moelle épinière est soumise à des variations temporelles du champ B0 liées à la respiration du patient, ce qui peut entraîner encore plus d'artefacts (par exemple, des problèmes de flou et d'incohérence de signal). De fait, plusieurs des méthodes d'IRM qui ont été développées pour le cerveau (par exemple, l'IRM fonctionnelle, l'IRM de diffusion, et l'imagerie spectroscopique) ne fonctionnent pas aussi bien au niveau de la moelle épinière. L'élimination de la variation de champ magnétique statique (généralement connue sous le nom de « shimming ») est généralement effectuée à l'aide de réseaux de grandes bobines inductives intégrées dans le scanner IRM. Bien qu'utile, la correction conventionnelle reste insuffisante pour la moelle épinière. Pour répondre aux défis de l'inhomogénéité du champ B0, ce projet comprend le développement de nouveaux appareils (des matrices de shims locaux) dédiés à la moelle épinière et de nouvelles stratégies d'optimisation (une correction prospective qui combat les effets de la respiration en temps-réel). En conséquence, des améliorations aux images écho-gradient (GRE) et échoplanaires (EPI) sont démontrées. ABSTRACT: Over 85,000 Canadians suffer from pathologies of the spinal cord—a condition that often entails motor, sensory, or functional losses. The development of quantitative imaging biomarkers could provide physicians with a better means of predicting treatment outcomes, for instance, to avoid unnecessary surgeries. To this purpose, magnetic resonance imaging (MRI) could prove useful given its ability to produce a variety of image contrasts which, by adjusting the acquisition parameters, can be tailored to reflect a range of tissue properties and physiologic functions. The spinal cord presents a challenge to advanced MRI techniques. The magnetic susceptibility of its anatomical surroundings is highly heterogeneous, which leads to significant magnetic field (B0) variation in the spinal cord itself. This frequently results in a variety of image artifacts, such as signal loss and geometric distortion. Moreover, the proximity of the spinal cord to the lungs produces significant temporal field variation during respiration which can result in additional problems such as blurred images and inconsistent signal measurements. As a result, many of the advanced MRI techniques developed for the brain (e.g., functional fMRI, diffusion, and spectroscopic imaging) remain impractical for the spinal cord. Eliminating static magnetic field variation (generally known as shimming) is commonly performed using arrays of large inductive coils integrated into the MRI scanner. While useful, conventional static shimming nevertheless remains inadequate for the spinal cord. To address the challenges of B0 field inhomogeneity, this work aims to develop new approaches to shimming to meet the particular the demands of MRI of the spinal cord. Through the use of new dedicated hardware (local shim arrays) and tailored optimization strategies (e.g. realtime/ prospective shimming to combat the effects of respiration), improvements to gradient-echo (GRE) and echo-planar images (EPI) are demonstrated
Harmonic Phase Processing In Magnetic Resonance Susceptibility Imaging
No full textThe popularity of magnetic resonance imaging (MRI) owes much to its flexibility. Sensitive to a host of different biophysical phenomena, parameters of the scan can be fine-tuned to highlight specific pathologies. One such mechanism for generating image contrast is magnetic susceptibility—the material property that defines how an object will distort an applied magnetic field such as that of the MR scanner. In functional MRI (fMRI), for instance, the unique magnetic signatures of oxygenated (diamagnetic) and deoxygenated (paramagnetic) blood are what permit the indirect measure of neuronal activity. However, rather than measuring the susceptibility itself, fMRI registers haemodynamic change as subtle gains and losses in the signal magnitude due to haem-iron induced dephasing of the proton spins. Susceptibility mapping, an emerging area in MRI, attempts to retrieve a direct measure of bulk susceptibility itself. Generally this is done, not by means of the standard magnitude image, but through the phase component of the signal which, in the idealized case, relates the magnetic field perturbation by a simple multiplicative constant. Several issues interfere with the construction of accurate susceptibility maps. Foremost is the obfuscation of the small-scale “local” field (i.e., that pertaining to susceptibility vari- ation within tissue) by the so-called “background” field, which owes predominantly to the comparatively substantial susceptibility shift between tissue and air. Whether the goal is to produce qualitatively useful images of the local field, or to map the susceptibility itself, the local field must first be isolated from the background. To isolate overlapping signals which are a priori unknown, the unique characteristics of the expected signals need to first be cod- ified. One family of methods for isolating the local field begins by asserting that, away from air-tissue interfaces, the background field should satisfy the partial differential equation of Laplace, whereas the local field should satisfy that of Poisson (viz., the background field should be harmonic, the local field non-harmonic). This classification informs a filtering technique based on the spherical mean value (SMV) property of harmonic functions: the mean of a harmonic function calculated over a spherical surface equates to the specific value taken by the function at the centre of the sphere. This thesis introduces another property of harmonic functions to the task of local field estimation: a harmonic function can be locally expressed by means of a convergent power series (viz., it is an analytic function). This property is first employed to characterize the SMV kernel as an estimator for the central field value when the field is discretized. Analysis reveals that when the field data is of a finite spatial resolution, the aim of accurate elimination of the background field via the SMV is fundamentally at odds with the aim of preserving the local field. Fortunately, given the rapid decay of the background field and its derivatives with distance from its field sources, the discrete SMV is nevertheless a robust estimator for field geometries such as those observed in the brain. In addition to the problem of finite image resolution, MR imaging of the head has finite spatial support as signal is generally absent in the skull and ever-absent in the surrounding air. The SMV cannot be used to estimate the background field wherever the spherical kernel extends beyond the edges of this support. Hence, in conventional SMV-filtering, field points within a distance from the edges equal to the radius of the employed kernel are discarded outright. This is a considerable obstacle to a number of clinical applications as it precludes analysis of features such as subdural haematomas and cortical lesions in pathologies such as multiple sclerosis. To recover local field across the edges of the brain, this study presents an extension to conventional SMV-filtering by appealing to the analytic nature of the back- ground field: by obtaining an initial SMV-estimate of the harmonic background field over a reduced inner portion of the brain, a three-dimensional Taylor expansion was performed to extend field coverage to the edges of the brain. The method is quantitatively assessed through a numerical experiment and qualitatively demonstrated on in vivo human brain data acquired at 4.7 T. Using a kernel radius typical of conventional methods, the extension recovered on average 26 % more in vivo brain volume
Psychospiritual Development of Female Adoptees Raised Within a Closed Adoption System: A Theoretical Model Within a Feminist and Jungian Perspective
No full textThis article proposes a transpersonal theoretical model suggesting that the embodiment of
the voice of the feminine is a significant catalyst for awakening the psychological and spiritual
growth and development of female adoptees. Existing Jungian and feminist theoretical
models regarding the psychological and spiritual implications for a female adoptee raised
within a closed adoption system will be discussed. The author will share her adopted voice
about her spiritual and psychological process toward finding wholeness using a hermeneutical
process of inquiry. The voices of birth mothers who relinquished their children will also be
included. Voice is then explored to be an essential component of the embodied feminine,
in turn becoming a catalyst of psychospiritual growth and developmental awakening for
female adoptees
Real-time correction of respiration-induced distortions in the human spinal cord using a 24-channel shim array
No full text
Real-time correction of respiration-induced distortions in the human spinal cord using a 24-channel shim array
No full textShim coil wire patterns for the 24-channel multi-coil "spine shim" (originally described in http://onlinelibrary.wiley.com/doi/10.1002/mrm.26354/
Tree productions of Capek's The Robber at The Vinohrady Theater
No full textThe aim of the bachelor thesis is to characterize three last stage productions of the Vinohrady theatre of the play Loupeznik by the well known playwright, author and a democrat Karel Čapek. Karel Čapek was one of the most remarkable authors of the 1920s and 1930s. The author of this thesis attempts to make a reconstruction of the last three stage productions of Loupeznik at the Vinohrady theatre based on available infomation found. The first and oldest one being stage production of 1972 by the director Frantisek Stepanek. The second one being the stage production by director Jan Novak of 1988. And the last and newest one is the stage production by director Thomas Topfer of 2015. The more detailed analysis will be provided to the first and third production respectively because of the more information available for these including the video recording of these two productions. On the other hand, for the second production very little material being available and thus to reconstruct this 1988 one based on the material was very difficult. In the order to reconstruct the productions the author bases his research upon archival theater reviews and studies in particular periodicals, photographical material from the productions and in some cases also audiovisual recordings. Other resources include also the..
Sustainable development of deltas: An international conference
No full textPREFACE Prince Claus of The Netherlands PROGRAMME \u95 Contents \u95 Introduction by Anne van Urk \u95 Conference programme \u95 Characteristics of the delta countries SUMMARIES OF KEYNOTES Future role and position of Public Works (Gerrit Blom) Sustainable development of deltas (lsmael Serageldin) The bank's approach to sustainable development of deltas: experience and lessons (Peter Sullivan) Public participation: risks and opportunities (L.E. Susskind) Public works: institutional agreement and social participation (Eduardo A. Duhalde) Technical innovation: can technology provide solutions (J. Blaauwendraad) What should Public Works Departments contribute to sustainable development in our common future (K. Topfer) Skills required by Public Works Departments in the 21st century (M.A.H. Abu-Zeid) COUNTRY/DELTA POSITION PAPERS China - Government of China Philippines - Samuel Costodio Vietnam: Red River Delta looking forward - Vu Trong Hong and Le Kim Truyen Thailand: The Chao Praya Delta and the development of Bangkok Metropolitan Region -Siripong Hungspreug, Ruengsak Suthakavatin, and Ksemsan Suwamarat Indonesia: Brantas delta and its development - Ministry of Public Works Bangladesh - A.T.M. Shamsul Huda Sri-Lanka: eroding coastlines, infrastructure and Ecosystem-based special area management - H. Nissanka R. Perera, and Jayampathy Samarakoon India: Indian economy and sustainable development - O.P. Sharma Pakistan: Indus delta - Malik Mohammad Saeed Khan Russia: St. Petersburg enters the 21st century - Yury V. Antonov Egypt: Overview of Egypt's Nile valley and delta - Abdei-Rahman M. Shalaby, Mona El-Kady, and Safwat Abdei-Dayem The Netherlands: How to continue the sustainable development in The Netherlands? Joost de Jong, Pieter Huisman, Henk Pauwels and Roxanne Powel Surinam - Ministry of Public Works, et al. Argentina: The Rfo de la Plata delta in the Argentine Republic - Presidency of the Nation, et al. VISIONS Skills and strategies needs of 'Public Works Departments': a view from the UN/Economic - UN/ECE Commission for Europe with a focus on an environmentally sustainable development of coastal areas Public Works gearing up for the 21st century - UNESCO UNIDO concept of Integrated Coastal Zone - UNIDO Management as a toolbox for environmentally sustainable development in deltas: The view of the World Meteorological Organization - WMO Capacities and skills in support of public health, the perspective of the World Health Organization - WHO The vision of the water boards - Association of Water Boards Orientability in a world in transformation - Delft Geotechnics Engineers in Public Works - KIVI Public Works in the 21st century - LWI Wanted: Support for the sustainable development of deltas - NCDO DIGITAL DELTAS for the 21st century - TNO Role and vision of contractors in coastal zone development - VBKOKWP-collectio
Ecological Aesthetics: Art in Environmental Design: Theory and Practice
No full textThe edited book juxtaposes the work of the German artist, Herman Prigann, against the work of others from Europe and the United States such as Helen and Newton Harrison, AMD and Art, and Jeroen van Westen. Articles addressing ecology and aesthetics were written by Dr. Jale Erzen, Department of Architecture, Middle East Technical University in Ankara; Prof Dr Massimo Venturi Ferriolo of the University of Salerno, Milan; and Dr Malcolm Miles of the University of Plymouth. The text closes with an overview of the issues in relation to cultural politics by Dr Klaus Topfer, former German Minister of the Environment.Collins’ chapter examines the question of aesthetics in artists’ work in the environment. The author hypothesizes that creative transformation has come unhinged from the impetus for primary authorship. Nature has come under full attack from the appetites of human culture and as a result the care for nature has become a cultural problem that must be addressed by the arts, sciences and the humanities. Working from a position of restoration ecology, the author makes a series of direct arguments for diversity as a standard aesthetic component, of social, environmental and economic systems. The text is framed within a specific history referencing scientists like E.O Wilson, and Gary Nabhan as well as environmental philosophers, landscape architects and other environmental practitioners. Also included in this text, are a series of full colour plates with descriptions presenting work done as principal investigator on “Nine Mile Run” and “3 Rivers 2nd Nature.
