Investigation of energy dissipation and capture through fission measurements

Fusion of atomic nuclei is a process in which two nuclei overcome their mutual Coulomb repulsion and merge together to form a single nucleus. Although the concept of nuclear fusion has been known for almost a century, only the more recent development of precision experimental measurements and new theoretical ideas demonstrated how essential it is to consider quantum superposition effects. It is now recognised that fusion cross sections at energies below and close to the barrier can only be understood if the colliding nuclei are considered to be in a coherent superposition of their internal states. The coupled channels model, which considers the coupling between the internal structure and the relative motion of the two colliding nuclei, has emerged as the most successful model of fusion. However, experimental measurements of fusion cross sections at energies above the barrier consistently fall below model predictions, the deviation appearing to increase with increasing charge product. These observations have led to a closer scrutiny of the way fusion is modelled. Currently, the colliding nuclei are considered to remain in coherent superposition right until the separation inside the barrier where fusion is simulated by imposing a boundary condition by imposing the incoming wave boundary condition. Thus the dissipation of kinetic energy that leads to fusion is not modelled explicitly. The question is whether energy dissipation starts even at larger separations, which can lead to some of the kinetic energy being lost well before separations at which fusion is simulated in the model. Such processes can potentially reduce fusion as the colliding nuclei will have less kinetic energy at the barrier. In this work, factors leading to the reduction of fusion in heavy ion collisions are explored, in particular, focus on the role energy dissipation plays in such reaction outcomes. To probe energy dissipative processes, a series of experiments were conducted using the 14UD tandem accelerator and superconducting LINAC at the Heavy Ion Accelerator facility at the Australian National University. In these experiments, a range of projectiles bombarded fissile targets at various beam energies. Reaction outcomes were detected in coincidence using the CUBE binary fission spectrometer. A systematic study of transfer-fission, fusion-fission and quasifission was carried out through the analysis of each reaction's kinematic properties and timescales. Additionally, a new method for determining quasifission cross sections was developed and used to extract cross sections. In this work, transfer-fission has been used as a proxy for energy dissipative processes since fission following transfer can only occur if the system formed following transfer has an excitation energy higher than the fission barrier. Transfer-fission was found to increase relative to total fission as a function of charge product. For each reaction, the proportion decreased as a function of energy relative to the capture barrier energy. It is suggested that fusion is suppressed by transfer reactions as the charge product increases, and that self-consistent models of fusion need to properly take into account energy dissipation even outside the barrier in order to accurately predict fusion probabilities for heavy ion reactions

Propyl gallate inhibits adipogenesis by stimulating extracellular signal-related kinases pathway in human adipose tissue-derived mesenchymal stem cells

Biological Sciences ProgramMesencymal stem cells (MSCs) are isolated from various mesenchymal tissues and differentiate into osteoblast, myocyte, and adipocyte. MSCs are easily obtained without ethical issue, and modulation of MSCs differentiation applies to various therapies. Moreover, the significance of modulating factor in MSCs differentiation is on the rise, we identified Propyl gallate, which can regulate differentiation of MSCs. PG is used as an additives in various foods that has antioxidant and anti-inflammatory effects. Although the function of PG is well identified in different cell types, it is unknown that PG has an effect on stem cell differentiation. We demonstrate that PG suppresses adipocyte differentiation in human adipose tissue-derived mesenchymal stem cells (hAMSCs) by reduced lipid droplets accumulation. Further, PG reduced expression of adipocyte-specific markers, including PPAR-??, C/EBP-??, adipocyte fatty acid-binding protein and lipoprotein lipase. PG inhibited adipogenesis of hAMSCs through ERK pathway and the inhibition was recovered in response to blockage of ERK activation. Collectively these results demonstrate unusual function of PG on adipocyte differentiation in hAMSCs and PG inhibits adipocyte differentiation through ERK signaling pathway and decrease of PPAR-?? activity.ope

Sulfonated polysulfone desalination membranes by melt extrusion

This dissertation discusses preparation and transport property characterization of sulfonated polysulfone desalination membranes by melt processing. One route to melt processing of high glass transition temperature polyelectrolytes, such as disulfonated poly(arylene ether sulfone) (BPS), involves mixing a plasticizer with the polymer. In this study, poly(ethylene glycol) (PEG) was used as a plasticizer for BPS. Currently, most ion containing membranes used for desalination, electrodialysis, etc. are prepared using solvent-based processing, which is costly and environmentally unfriendly. The goal of this study has been to conduct a fundamental exploration of processing conditions useful for preparing desalination membranes without the use of solvents. Long term, this research may has the foundation for melt processing to prepare desalination membranes having equivalent or better separation properties as those of conventional solution processed membranes.Chemical Engineerin

Biology of deep-sea calanoid copepod genus Pleuromamma with particular references to phylogeny, pore signatures, moulting and life history.

The pore signature of calanoid copepods is of increasing interest in phylogenetic and biogeographical studies. Some recent studies have been restricted to the urosome on the assumption that most of the species-specific information resides there. The present study tests that assumption in eight Pleuromamma species by assessing the signatures of the cephalosome, metasome and urosome separately in each species. Most of the species- specific information is in the urosome, but a significant proportion also resides in the cephalosome and a lesser component in the metasome. Changes in the pore signatures between the species parallel changes in other morphological characters. The pore signatures shed further light on the phylogeny of the Pleuromamma species which had been diffuse in studies of conventional morphology of this genus. Interspecific differences in the pore signatures occur as early as copepodid III. Sexual differences in the pore signature are found in copepodid IV and are primarily evident in the urosome of the adult. The species-specific components of the urosomal signature are greater in the female than in the male. In general, the degree of the intraspecific variation in the pore signature increases with increasing number of the total integumental pores and is limited to 10% or less of the total. Inter- and intraspecific variation are an expression of the phylogenetic grouping of species, or generic similarities between the species within the genus. In calanoid copepods, external and internal morphological changes associated with the intermoult cycle in Pleuromamma robusta conform with those in other crustaceans. Early stages of the intermoult cycle are the completion of the integumental structure and somatic tissue after the previous ecdysis and late stages are in preparation for the next ecdysis. Adult copepods do not moult, but progress through part of the moult cycle exhibited by earlier copepodid stages. Changes in the integumental structure were evident as increases in the thickness of the cuticle throughout the period of the intermoult cycle, which also affect the body appearance of copepodids such as soft and hard bodies. The different body appearance is of great use for studies of population dynamics, e.g. detection of the timing of the population reconstruction, overlapping generations, the identifjcation of the newly recruited stock and the seasonal changes of the recruitment rate. The Rockall Trough population of P. robusta produces three generations per year. The peak of reproduction of this species was in September and was followed by a hiatus of reproduction in November. In addition, significant relationships between day and night vertical distribution of individuals of copepodid V and adults at different stages of the intermoult cycle In P. robusta were found in relation to their mating behaviour

The Effects of Merger and Acquisition on the Price of Insurance and Firm Performance in the U.S. Property-Liability Insurance Industry

Although the economic motivation and efficiency effects of mergers and acquisitions (M & As) in the insurance industry have been discussed, none of the prior studies have addressed the relationship between M & A activity and insurance price change. In addition, little is known about the effect of diversification on the differences in insurance price across lines. The main objective of the dissertation is to provide evidence on these issues. A secondary objective is to investigate the relationship between M & A activity and insurer’s efficiency and financial performance. We also examine various firm characteristics that affect insurance price differences across lines and that influence insurer’s efficiency and performance. We conduct fixed effects model regressions to test our hypotheses using unbalanced panel data over the sample period 1989-2004. The empirical tests indicate that the price of insurance for newly formed insurers decreases following the M & As and diversified insurers charge lower prices than less diversified firms. Our result is consistent with one possible explanation that acquiring insurers reduce overall underwriting risks and more efficiently manage the frictional costs of capital through geographic and/or product line diversification by engaging in the M & As and therefore gain a competitive advantage in pricing. Our analysis also reveals a number of other interesting results. We find that insurance price is positively related to marginal capital allocation and inversely related to firm insolvency put value, suggesting the importance of incorporating insolvency risk and marginal capital costs in pricing lines of insurance business. We also find that the price of insurance is inversely related to cost efficiency, consistent with the efficiency structure hypothesis. However, the market share variable is not significant, implying that market power that can arise from M & A activity may not be a big concern for insurance regulators. In the analysis of efficiency and financial performance, we provide evidence that acquirers’ overall cost and revenue efficiency and financial performances decrease following M & As. We also find that more focused insurers outperform the diversified insurers