Decision-Stage Method: Convergence Proof, Special Application, and Computation Experience

This paper presents a new method for obtaining exact optimal solutions for a class of discrete-variable non-linear resource-allocation problems. The new method is called the decision-state method because, unlike the conventional dynamic programming method which works only in the state space, the new method works in the state space and the decision space. It generates and retains only a fraction of the points in the state space at which the state functions are discontinuous; and thus overcomes to some extent the curse of dimensionality. It carries the cumulative decision-strongs associated with these points, and thus avoids the backtracking entailed by the conventional dynamic programming method for recovering the optimal decisions. A concise and complete statement of the method is given in Algorithm 2 and it is proved that the algorithm finds all exact optimal solutions. In addition the method is adapted for solving some problems with special structures such as block-angular or split-block-angular constraints and the resultant substantial advantages are demonstrated. The performance of Algorithm 2 on many resource-allocations problems is reported, along with investigations on many tactical decisions which have substantial impact on the performance. The performance of the computer implementation of Algorithm 2 is compared with that of the MMDP algorithm and it showed that for the class of problems at which the two are aimed, the decision-state Algorithm 2 performed better than MMDP algorithm both in terms of storage requirement and solution time. In fact, it achieved an order of magnitude saving in storage requirement.

Study of the photovoltaic effect in thin film barium titanate

The photoelectric effect in structures consisting of metal deposited barium titanate film silicon is described. A radio frequency sputtering technique is used to deposit ferroelectric barium titantate films on silicon and quartz. Film properties are measured and correlated with the photoelectric effect characteristics of the films. It was found that to obtain good quality pin hole free films, it is necessary to reduce the substrate temperature during the last part of the deposition. The switching ability of the device with internal applied voltage is improved when applied with a ferroelectric memory device

Control of the Onset of Filamentation in Condensed Media

Propagation of intense, ultrashort laser pulses through condensed media like crystals of BaF$_2$ and sapphire results in the formation of filaments. We demonstrate that the onset of filamentation may be controlled by rotating the plane of polarization of incident light. We directly visualize filamentation in BaF_2 via six-photon absorption-induced fluorescence and, concomitantly, by probing the spectral and spatial properties of white light that is generated.Comment: To appear in Phys. Rev.

IMAGING SPECIFIC ABSORPTION RATE WITH MR THERMOMETRY USING PARAMAGNETIC LANTHANIDE COMPLEXES AND IN VIVO GABA MR SPECTROSCOPY IN MOVEMENT DISORDERS

Magnetic Resonance Imaging (MRI) is a popular imaging modality due to its ability to provide excellent soft tissue contrast without exposure to ionizing radiation. It can be used for temperature monitoring (thermometry) as well as for assessing the biochemistry in vivo (MRS). This dissertation focuses separately on the development, application and quantitation issues of these two aspects of MRI

Novel players in the rescue of ß-cells from inflammation-mediated destruction in type 2 diabetes mellitus

Chronic inflammation is consequential to the etiology of both T1D and T2D. Cytokine and chemokine production by infiltrating macrophages and by ß-cells themselves in a diabetic milieu contributes to their destruction in inflamed islets and thus to progression of diabetes. In order to find potential targets for inhibition of this deleterious response of islets, the investigation of underlying mechanisms for triggering inflammation is essential. The expression of a novel family of adhesion molecules called Sialic acid-binding immunoglobulin-like lectins (Siglecs) in pancreatic islets was observed in cell type specific manner. Siglec-7, expressed on the ß-cells, was down-regulated in diabetes. Over-expression of Siglec-7 in cultured isolated islets prevented ß-cell dysfunction and apoptosis under chronic diabetic stimuli and also in diabetic islets. The protective effect of Siglec-7 was mediated by the inhibition of the NF-κB pathway and the subsequent decrease in cytokine secretion. Also, activated immune cells showed loss of Siglec-7 expression. Ultimately, restoration of Siglec-7 in stressed islets caused a reduction in the number of recruited migrating monocytes. Siglec-7 expression on ß-cells contributes to the inhibition of pro-inflammatory activation of these cells in diabetes. Restoration of Siglec-7 expression or signaling may be a potential therapeutic strategy to preserve ß-cell function and mass in the manifestation of diabetes. This strategy would not only rescue the ß-cells, but also inhibit systemic inflammation observed in T2D