Large single crystals, as nearly perfect as possible, are required for magnetic resonance studies of the solid state. A limited number of substances occur naturally in crystals of sufficient size or purity for this type of experiment. Most of the nuclear magnetic resonance work done to date on single crystals has been performed using naturally occurring crystals. Section I of this thesis describes methods used to grow suitable crystals artificially, thus extending the scope of the magnetic resonance experiments. The orthorhombic sodium dihydrogen orthophosphate dehydrate has been produced in large single crystals which were used subsequently in the study of the nuclear magnetic resonance absorption spectrum of Na-23 in this crystal. The spectrum was observed as the crystal was rotated about the three crystallographic axes which are mutually perpendicular for the orthorhombic case. A maximum of twelve lines were observed when neither of the crystallographic axes were perpendicular to the external magnetic field. The number of lines was reduced to six when one of the axes was made perpendicular to the field, while only three lines were observed when two crystallographic axes were made perpendicular to the external magnetic field. These observed numbers of lines were interpreted by assuming four Na-23 sites, possessing identical eigenvalues and differing only in their orientation. These four sites are related by three mutually perpendicular two-fold rotation axes, each of which must be parallel to one of the three crystallographic axes. This interpretation is in complete accord with the space group P222 assigned to NaH2PO42H2O from morphological data. The complete set of properties of the quadruple coupling tensor was determined at each of the Na-23 sites. The value of the quadruple coupling constant (eQ Φzz)/h where Q is the nuclear quadruple moment and Φzz is the largest principle value of the electric field gradient tensor is: 1179.0 ± 0.5 kc/sec. The value of the asymmetry parameter η defined as (Φxx – Φyy)/Φzz is: 0.466 ± 0.005. The table of the direction cosines of the principle axes of the electric field gradient tensor with respect to the crystallographic axes appear in Table VII. / Thesis / Master of Science (MSc)

published_or_final_version / abstract / Orthopaedics and Traumatology / Doctoral / Doctor of Philosophy

The best for PhD thesis in the Faculties of Arts, Architecture, Business & Economics, Education, Law and Social Sciences (Universityof Hong Kong), Li Ka Shing prize, 2006-2007 / published_or_final_version / abstract / Psychology / Doctoral / Doctor of Philosophy

In the work undertaken here, NMR has been used to ascertain the structure of some 1,2,4-triazoles. The investigation provides information concerning the structure of potentially tautomeric triazoles such as hydroxy- and aminotriazole. Connected with this aspect of triazole chemistry is the larger problem of mesohydric tautomerism. The present study also yields information for a comparison of substituent effects in triazoles, N-heteroaromatic substances and benzene.

No description available.

For the nervous system, there is evidence of relative shortening of the spinal cord, reflected by both reduced cord length to vertebral column ratio and a change in cross-sectional morphology of the cord. The cerebellar tonsils are low-lying in AIS subjects while significant regional volume differences in the brain are also evident between AIS subjects and controls. / From the results of this series of study, AIS girls are found to have morphological difference in multiple aspects when compared with age- and sex-matched normal controls. / Idiopathic scoliosis is a common worldwide problem and has been treated for many decades; however, there still remain uncertain areas about this disorder. Its involvement and impact on different parts of the human body remain underestimated due to lack of technology in imaging for objective assessment in the past. / In the skeletal system, AIS girls have generalized osteopenia and abnormal growth of the appendiceal skeleton. For the axial skeleton, abnormal ossification patterns have been found affecting both the longitudinal growth and axial growth pattern of the vertebral column. There is overgrowth of the anterior vertebral column, reversed asymmetry of the neural arch and smaller pedicle at the concavity of the scoliotic curve in AIS, suggestive of asynchronous growth between membraneous and endochondral ossifications. In the skull, both calvarium and basicranium are found have regional difference (including foramen magnum) between AIS subjects and controls, which is again probably reflecting a systemic process of asynchronous growth between membraneous and endochondral ossification. / It was concluded that the hypothesis "In adolescent idiopathic scoliosis, advanced magnetic resonance imaging techniques can be used to identify systemic features which are suggestive of asynchronous neuro-osseous growth of the disorder" was confirmed. (Abstract shortened by UMI.) / Taking together, the abnormalities in the skeletal system and nervous system are likely to be inter-related and reflecting a systemic process of asynchronous neuro-osseous growth. The above findings help to explain a number of well documented neurological abnormalities in AIS: Anatomically, there is increased incidence of Chiari malformation and syringomyelia in AIS subjects, while functionally, abnormal somatosensory evoked potential (SSEP) results, impaired postural balance, poor performance on combined visual and proprioceptive testing and spatial orientation testing as well as reports of abnormal nystagmus response to caloric testing are known to be associated with AIS. / The advances in imaging technique and image analysis technology have provided a novel approach for the understanding of the phenotypic presentation of neuro-osseous changes in AIS subjects as compared with normal controls. Dynamic imaging also assists in functional assessment of pulmonary function and respiratory mechanism in AIS subjects. / The hypothesis to be tested in this series of studies is: "In adolescent idiopathic scoliosis, advanced magnetic resonance imaging techniques can be used to identify systemic features which are suggestive of asynchronous neuro-osseous growth of the disorder". This thesis was based on a series of eight studies which were aimed to explore the "unknown" anatomical features in the skeletal and neural systems in AIS by the application of new advanced technique of MR imaging and sophisticated image analysis programs. / We are the first group who has undertaken a comprehensive morphological assessment of the skeletal and nervous systems in AIS subjects based on imaging findings which have not been reported previously. For the first time in literature, the spinal cord and vertebral column, brain and skull were thoroughly analyzed in AIS subjects and compared with age- and sex-matched normal controls. Detailed correlations with clinical information, neurological tests have also been made. As an appendix, MR imaging findings of the pulmonary system in AIS, including the lung, chest wall and diaphragms are also presented at the end of the thesis. / Chu Chiu-wing, Winnie. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 0976. / Thesis (M.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 248-267). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / School code: 1307.

No description available.

Using Graphic Processor Unit (GPU) to process the parallel operation via Compute Unified Device Architecture (CUDA) is a new technology in recent years. In the past, the GPU has been used in parallel operation but it was not easy for programming so that it couldn¡¦t be widely used in applications. CUDA is the newly-developed environment based on C language mainly for improving the complexity in programming with CUDA. The applications of GPU with CUDA has been expending to various fields gradually due to support of IEEE floating point as well as its lower cost in hardware while comparing to the super computers. Magnetic Resonance Spectroscopy (MRS) has the feature of non-invasive to probe the concentration distributed of metabolites in vivo. It can assist doctor in clinical diagnosis. The Magnetic Resonance Spectroscopy Imaging (MRSI) is imaging by many Signal Voxel Spectroscopy (SVS) to become multi-dimension MRS image. In MRSI, it can offer more information than SVS. CUDA are applied to MR image widely such as accelerating the image reconstruction and promoting the image quality, but in MRS it is seldom for the related application. In this paper, we using the CUDA to applied in MRS, the MRSI data pre-processing, to accelerate the spatial location in MRSI. In this work, we firstly use random data with different dimensions: 1D (one-dimension), 2D and 3D to evaluate the performance of Fourier transformation by using CUDA. We also finally apply some GE 2D/3D MRSI data to see how the acceleration of using CUDA works. Our results show that the acceleration rate of Fastest Fourier Transform (FFT) with CUDA in 1D, 2D and 3D random data largely increases as the data size increases. In the experiment of 2D/3D MRSI data, we find that using CUDA for accelerating the MRSI RAW-file generating procedure would avoid the data moving times, and it is not good for CUDA 1D FFT with parallel architecture while too small data amount processing in kernel. Therefore, how to solve the relationship between MRSI data format with CUDA FFT library and how to decrease the data moving time will discuss in the study.

LCModel, which is performed on Linux, has been widely used for quantitative analysis of MRS. Its interface, LCMgui, converts MRS data of various formats to RAW file for LCModel analysis automatically. In this work, we had a web-based MRS analysis tool for GE MRS, GE MRS with Phase-Array and GE 2D-MRSI and improve the capability of web-based MRS analysis tool for GE 3D-MRSI, Siemens MRS/MRSI, and Philips MRS/MRSI. Meanwhile, T2 correction has been involved in the absolute quantification with LCModel. With the same echo-time, the different T2 value of each metabolite results in different degree of signal decay. In order to correct and make absolute concentrations more accurate, we exploit a factor to correct effect of different T2. Two groups of MRS data (TE = 35 and 272 ms) have been studied for comparison.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 126-139). Available also in a digital version from Dissertation Abstracts.