The XMM Newton spectra of the 2012 outburst of the black-hole candidate 4U 1630-47 revisited

Recent XMM-Newton observations of the black-hole candidate 4U 1630-47 during the 2012 outburst revealed three relativistically Doppler-shifted emission lines that were interpreted as arising from baryonic matter in the jet of this source. Here we reanalyse those data and find an alternative model that, with less free parameters than the model with Doppler-shifted emission lines, fits the data well. In our model we allow the abundance of S and Fe in the interstellar material along the line of sight to the source to be non solar. Among other things, this significantly impacts the emission predicted by the model at around 7.1 keV, where the edge of neutral Fe appears, and renders the lines unnecessary. The fits to all the 2012 XMM-Newton observations of this source require a moderately broad emission line at around 7 keV plus several absorption lines and edges due to highly ionised Fe and Ni, which reveal the presence of a highly-ionised absorber close to the source. Finally, our model also fits well the observations in which the lines were detected when we apply the most recent calibration files, whereas the model with the three Doppler-shifted emission lines does not.Comment: 8 pages, 6 figure

Exploring online brand choice at the SKU level : the effects of internet-specific attributes

E-Commerce research shows that existing studies on online consumer choice behavior has focused on comparative studies of channel or store choice (online or offline), or online store choice (different e-tailers). Relatively less effort has been devoted to consumers’ online brand choice behavior within a single e-tailer. The goal of this research is to model online brand choice, including generating loyalty variables, setting up base model, and exploring the effects of Internet-specific attributes, i.e., order delivery, webpage display and order confirmation, on online brand choice at the SKU level. Specifically, this research adopts the Multinomial Logit Model (MNL) as the estimation methods. To minimize the model bias, the refined smoothing constants for loyalty variables (brand loyalty, size loyalty, and SKU loyalty) are generated using the Nonlinear Estimation Algorithm (NEA). The findings suggest that SKU loyalty is a better predictor of online brand choice than brand loyalty and size loyalty. While webpage display has little effect on the brand choice, order delivery has positive effect on the choice. Online order confirmation turns out to be helpful in choice estimation. Moreover, online consumers are not sensitive to net price of the alternatives, but quite sensitive to price promotion. These results have meaningful implications for marketing promotions in the online environment and suggestions for future research

Mathematical modelling of bone remodelling in mechanical, electro-magnetic fields at the cellular level

The skeleton is a metabolically active organ that undergoes continuous remodelling throughout life. At the cellular level, bone remodelling is an organised process whereby osteoclasts remove old bone and osteoblasts replace them with newly formed bone. The osteoclasts and osteoblasts work together in a coupled manner within a so-called 'basic multicellular unit' (BMU). Bone remodelling helps to repair microdamages in bone matrix, preventing the accumulation of old bone. It also plays an important role in maintaining plasma calcium homeostasis. The regulation of bone remodelling is both systemic and local. The most important systemic regulator is parathyroid hormone (PTH), which has been used as a therapy to treat osteoporosis in clinics; however, the underlying mechanism by which PTH is regulated is still not clear. As far as local regulation of bone remodelling is concerned, the discovery of the RANKIRANKL/OPG pathway is significant to the understanding of the interaction between osteoclastic cells and osteoblastic cells in BMU. A large number of therapeutic drugs and other stimuli have been found to apply their effects via RANKIRANKL/OPG. Mechanical stimulus has significant influence on bone remodelling. Disuse or lack of loading causes bone remodelling with bone resorption dominating bone formation and thus a loss of bone mass or density. Conversely, overuse or increased loading causes bone mass or density to increase. Additionally, loadings with different characteristics such as frequency, number of loading cycles in a session and rest time between loading bouts affects bone remodelling differently. However, the underlying mechanisms are not fully understood despite a great deal of experimental work in this field. Pulsed electro-magnetic fields (PEMF) devices have been widely used in clinics to treat bone fracture non-union and shorten the recovery period of fracture. Despite the clinical success, it is still not clear how PEMF stimulus interacts with cells, factors or molecules that are involved in bone remodelling. This thesis will use a computational system biology approach to address the issues proposed above. Computational system biology is a systems biology approach that integrates experimental and computational research in order to understand complex biological systems such as bone remodelling. Based on the latest experimental results and mathematical advances, a mathematical model of bone remodelling at the cellular level is developed with PTH included. Building on this platform model, mechanical stimulus and PEMF are taken into account. Thus, their effects on bone remodelling and the underlying control mechanisms at the cellular level are investigated. The work in the thesis will further current understanding of bone remodelling at the cellular level. The quantitative analysis using our model will help pharmacological and non-pharmacological therapies developments, which eventually benefit patients who suffer from bone loss diseases such as osteoporosis

Design of Hapten Synthesis and Antibody Characterization of G-group Aflatoxins

Food and feed contamination with Aflatoxins pose a serious threat to human health and animal husbandry development and has caused widespread concern, among them, G-group Aflatoxins as the main pollutant has attracted more and more attention. In order to establish a rapid, sensitive, specific and efficient immunoassay method for G-group aflatoxins, this study aimed to designed to synthesize 3 immunogens and coating antigens and identified by UV and SDS-PAGE. Then used to immunize Balb/c mice with prepared of three immunogen the titers were determined by indirect ELISA and the sensitivity was determined by competitive indirect ELISA (icELISA), the specificity was assessed by the cross-reaction test (CR). The results of UV and SDS-PAGE showed that the three immunogens and the corresponding coated antigens were successfully synthesized and the best one was SA method among three synthesis methods of G-group AF artificial antigen and its conjugation ratio of AFG1 to BSA was about 5.64∶1. The immune efficacy of SA method was the best, its AFG1 pAb had high titers of 1∶(6.4×103) by indirect ELISA, a good sensitivity with the 50 % inhibition concentration(IC50) of 13.6 μg/kg－1 to AFG1 by blocking ELISA and a high CR to AFG2 of 82.19 %, it showed high specificity for other aflatoxins. The experimental results not only obtained the ideal G group aflatoxin antibody, but also established a substance and technology foundation for G group aflatoxin immunization methods, and can be referenced in the similar tests