The Politics of Union and Citizenship: The Evolution of British Constitutional Policy Towards Malaya and Singapore 1942-1948.

World War II, by unleashing new forces, had precipitated a reappraisal of British policy towards Malaya; it also afforded British planners an opportunity to rationalise the pre-war structures which had kept Malaya constitutionally disunited and racially divided. Isolated in their offices in Whitehall, Colonial Office officials devised the Malayan Union policy, embracing in a "union" all the Malay States and including, from the Straits Settlements, Penang and Malacca but excluding Singapore, which developed as a separate constitutional entity although the possibility of a future "fusion" with the proposed Malayan Union was not discounted; the new arrangements envisaged also the creation of a form of "common citizenship" that would confer political rights to Malaya's non-Malay population. When the war ended, the British proceeded, as planned, to implement the Malayan Union scheme in April 1946 only to replace it with the Federation of Malaya in February 1948; the provisions for citizenship were also significantly "tightened" by 1948 to include only a smaller number of non-Malays. The decision to scrap the Malayan Union, however, was taken by early July 1946, barely three months after its inception. This study traces the origins of the Colonial Office's plans for "union" and "citizenship", examines the assumptions which had guided British planners and how these had been overturned by post-war developments, and discusses the interaction of historical forces which led eventually to the demise of the Malayan Union and the creation of the Federation in 1948. It analyses also the separate political development of Singapore and the attempts to unite the Island with the Mainland, a process which succeeded, in retrospect, only briefly in 1963 and only then to result in separation again in 1965

Microvessel structure formation in a 3D perfused co-culture of rat hepatocytes and liver endothelial cells

Thesis (Ph. D.)--Massachusetts Institute of Technology, Biological Engineering Division, 2006.Includes bibliographical references (leaves 108-122).Many liver physiological and pathophysiological behaviors are not adequately captured by current in vitro hepatocyte culture methods. A 3D perfused microreactor previously demonstrated superior hepatic functional maintenance than conventional 2D cultures, and was hypothesized to provide an environment favorable to endothelial cell maintenance and morphogenesis. This dissertation focuses on characterizing the 3D perfused co-culture of primary hepatocyte fraction with primary rat liver endothelial isolate. Scanning electron microscopy revealed significantly higher numbers of pore-like structures on the co-culture tissue surface resembling liver sinusoids compared to cultures containing only the hepatocytes fraction (mono-culture). EGFP-labeled endothelial cells proliferated moderately and organized into microvessel-like structures as observed by in situ multi-photon microscopy. By mixing female endothelial cells with male hepatocytes, the female cell population increased from initially -7% on day 1 to -12% on day 13, as determined by quantitative PCR on genomic DNA. The maintenance and morphogenesis of endothelial cells were not observed in parallel 2D collagen gel sandwich cultures. Immunohistochemistry further confirmed the presence of sinusoidal endothelia within the 3D co-culture tissue, as well as other non-parenchymal cells in both 3D mono-culture and co-culture.(cont.) Global transcriptional profiling confirmed the loss of endothelia in 2D culture as the comparison between mono-culture and co-culture showed substantial differential expression levels only in the 3D format. The majority of the genes expressed substantially higher in 3D co-culture than mono-culture was found to be endothelia-specific. A group of key liver metabolism genes, however, do not show significant expression differences between the 3D cultures. This study concludes that the 3D perfused microreactor maintains non-parenchymal cells better than the 2D format, and the retention of non-parenchymal cells in the primary hepatocyte fraction likely contributes to the maintenance of key hepatic function gene expression. Additional endothelial cells organize into microvessel-like structures in this environment, but exert little influence on the gene expression of most key liver transcription factors and metabolism enzymes. Therefore 3D cultures may eliminate the need of co-cultures for applications focusing on metabolic behaviors of hepatocytes, and 3D endothelial-hepatocyte co-cultures may prove useful in studies where proper endothelium structure is required, such as cancer metastasis.by Albert J. Hwa.Ph.D

The impact of system matrix dimension on small FOV SPECT reconstruction with truncated projections

Purpose: A dedicated cardiac hybrid single photon emission computed tomography (SPECT)/CT scanner that uses cadmium zinc telluride detectors and multiple pinhole collimators for stationary acquisition offers many advantages. However, the impact of the reconstruction system matrix (SM) dimension on the reconstructed image quality from truncated projections and 19 angular samples acquired on this scanner has not been extensively investigated. In this study, the authors aimed to investigate the impact of the dimensions of SM and the use of body contour derived from adjunctive CT imaging as an object support in reconstruction on this scanner, in relation to background extracardiac activity. Methods: The authors first simulated a generic SPECT/CT system to image four NCAT phantoms with various levels of extracardiac activity and compared the reconstructions using SM in different dimensions and with/without body contour as a support for quantitative evaluations. The authors then compared the reconstructions of 18 patient studies, which were acquired on a GE Discovery NM570c scanner following injection of different radiotracers, including 99mTc-Tetrofosmin and 123I-mIBG, comparing the scanner\u27s default SM that incompletely covers the body with a large SM that incorporates a patient specific full body contour. Results: The simulation studies showed that the reconstructions using a SM that only partially covers the body yielded artifacts on the edge of the field of view (FOV), overestimation of activity and increased nonuniformity in the blood pool for the phantoms with higher relative levels of extracardiac activity. However, the impact on the quantitative accuracy in the high activity region such as the myocardium, was subtle. On the other hand, an excessively large SM that enclosed the entire body alleviated the artifacts and reduced overestimation in the blood pool, but yielded slight underestimation in myocardium and defect regions. The reconstruction using the larger SM with body contour yielded the most quantitatively accurate results in all the regions of interest for a range of uptake levels in the extracardiac regions. In patient studies, the SM incorporating patient specific body contour minimized extracardiac artifacts, yielded similar myocardial activity, lower blood pool activity, and subsequently improved myocardium-to-blood pool contrast (p\u3c0.0001) by an average of 7% (range 0%-18%) across all the patients, compared to the reconstructions using the scanner\u27s default SM. Conclusions: Their results demonstrate that using a large SM that incorporates a CT derived body contour in the reconstruction could improve quantitative accuracy within the FOV for clinical studies with high extracardiac activity

Transformer-based Dual-domain Network for Few-view Dedicated Cardiac SPECT Image Reconstructions

Cardiovascular disease (CVD) is the leading cause of death worldwide, and myocardial perfusion imaging using SPECT has been widely used in the diagnosis of CVDs. The GE 530/570c dedicated cardiac SPECT scanners adopt a stationary geometry to simultaneously acquire 19 projections to increase sensitivity and achieve dynamic imaging. However, the limited amount of angular sampling negatively affects image quality. Deep learning methods can be implemented to produce higher-quality images from stationary data. This is essentially a few-view imaging problem. In this work, we propose a novel 3D transformer-based dual-domain network, called TIP-Net, for high-quality 3D cardiac SPECT image reconstructions. Our method aims to first reconstruct 3D cardiac SPECT images directly from projection data without the iterative reconstruction process by proposing a customized projection-to-image domain transformer. Then, given its reconstruction output and the original few-view reconstruction, we further refine the reconstruction using an image-domain reconstruction network. Validated by cardiac catheterization images, diagnostic interpretations from nuclear cardiologists, and defect size quantified by an FDA 510(k)-cleared clinical software, our method produced images with higher cardiac defect contrast on human studies compared with previous baseline methods, potentially enabling high-quality defect visualization using stationary few-view dedicated cardiac SPECT scanners.Comment: Early accepted by MICCAI 2023 in Vancouver, Canad

A High Resolution CMOS Imager With Active Pixel Using Capacitively Coupled Bipolar Operation

The active pixel sensor technology promises high performance than conventional CCD imagers. This paper reports a new high resolution CMOS imager with one transistor active pixel sensing based on capacitor-coupled bipolar action. The base capacitor is pulsed negatively for image integration and positively for image sensing. The pixel size is 5.9um x 5.9um (on 0.8um design rule). The prototype imager has an array of 480 x 640 and operating at 5v Vcc. This active pixel structure is promising for future high-performance and high-density imagers in the information highway era

Reflective tilted fiber bragg grating refractometer based on strong cladding to core recoupling

A novel in-fiber structure for power-referenced refractometry with the capability to measure surrounding refractive index (SRI) as low as 1.33 is proposed and demonstrated. A short optical fiber stub containing a weakly tilted Bragg grating is spliced to another fiber with a large lateral offset. The reflection from this structure occurs in two well-defined wavelength bands, the Bragg reflected core mode and the cladding modes. The cladding modes reflect different amounts of power as the SRI changes, while the core-mode reflection from the same weakly tilted FBG remains unaffected by the SRI. The power reflected in the core mode band can be used as a reliable reference to cancel out any possible power fluctuations. The proposed refractometer with improved sensitivity for low SRI measurement together with the tip-reflection sensing feature, is a good candidate for sensing in chemical and biological applications

Symmetries and Fixed Point Stability of Stochastic Differential Equations Modeling Self-Organized Criticality

A stochastic nonlinear partial differential equation is built for two different models exhibiting self-organized criticality, the Bak, Tang, and Wiesenfeld (BTW) sandpile model and the Zhang's model. The dynamic renormalization group (DRG) enables to compute the critical exponents. However, the nontrivial stable fixed point of the DRG transformation is unreachable for the original parameters of the models. We introduce an alternative regularization of the step function involved in the threshold condition, which breaks the symmetry of the BTW model. Although the symmetry properties of the two models are different, it is shown that they both belong to the same universality class. In this case the DRG procedure leads to a symmetric behavior for both models, restoring the broken symmetry, and makes accessible the nontrivial fixed point. This technique could also be applied to other problems with threshold dynamics.Comment: 19 pages, RevTex, includes 6 PostScript figures, Phys. Rev. E (March 97?

2-loop Functional Renormalization Group Theory of the Depinning Transition

We construct the field theory which describes the universal properties of the quasi-static isotropic depinning transition for interfaces and elastic periodic systems at zero temperature, taking properly into account the non-analytic form of the dynamical action. This cures the inability of the 1-loop flow-equations to distinguish between statics and quasi-static depinning, and thus to account for the irreversibility of the latter. We prove two-loop renormalizability, obtain the 2-loop beta-function and show the generation of "irreversible" anomalous terms, originating from the non-analytic nature of the theory, which cause the statics and driven dynamics to differ at 2-loop order. We obtain the roughness exponent zeta and dynamical exponent z to order epsilon^2. This allows to test several previous conjectures made on the basis of the 1-loop result. First it demonstrates that random-field disorder does indeed attract all disorder of shorter range. It also shows that the conjecture zeta=epsilon/3 is incorrect, and allows to compute the violations, as zeta=epsilon/3 (1 + 0.14331 epsilon), epsilon=4-d. This solves a longstanding discrepancy with simulations. For long-range elasticity it yields zeta=epsilon/3 (1 + 0.39735 epsilon), epsilon=2-d (vs. the standard prediction zeta=1/3 for d=1), in reasonable agreement with the most recent simulations. The high value of zeta approximately 0.5 found in experiments both on the contact line depinning of liquid Helium and on slow crack fronts is discussed.Comment: 32 pages, 17 figures, revtex