Riemann-Hilbert problems for poly-Hardy space on the unit ball

In this paper, we focus on a Riemann–Hilbert boundary value problem (BVP) with a constant coefficients for the poly-Hardy space on the real unit ball in higher dimensions. We first discuss the boundary behaviour of functions in the poly-Hardy class. Then we construct the Schwarz kernel and the higher order Schwarz operator to study Riemann–Hilbert BVPs over the unit ball for the poly- Hardy class. Finally, we obtain explicit integral expressions for their solutions. As a special case, monogenic signals as elements in the Hardy space over the unit sphere will be reconstructed in the case of boundary data given in terms of functions having values in a Clifford subalgebra. Such monogenic signals represent the generalization of analytic signals as elements of the Hardy space over the unit circle of the complex plane

Involvement of p300 in constitutive and HIV-1 Tat-activated expression of glial fibrillary acidic protein in astrocytes

HIV-1 Tat protein is an important pathogenic factor in HIV-1-associated neurological diseases. One hallmark of HIV-1 infection of the central nervous system (CNS) is astrocytosis, which is characterized by elevated GFAP expression in astrocytes. We have shown that Tat activates GFAP expression in astrocytes (Zhou, et al., Mol. Cell. Neurosci. 27:296, 2004) and that GFAP is an important regulator of Tat neurotoxicity (Zou, et. al., Am. J. Pathol. 171:1293, 2007). However, the underlying mechanisms for Tat-mediated GFAP up-regulation are not understood. In the current study, we reported concurrent up-regulation of adenovirus E1a-associated 300 kDa protein p300 and GFAP in Tat-expressing human astroytoma cells and primary astrocytes. We showed that p300 was indeed induced by Tat expression and HIV-1 infection and that the induction occurred at the transcriptional level through the cis-acting elements of early growth response 1 (Egr-1) within its promoter. Using siRNA, we further showed that p300 regulated both constitutive and Tat-mediated GFAP expression. Moreover, we showed that ectopic expression of p300 potentiated Tat transactivation activity and increased proliferation of HIV-1-infected astrocytes, but had little effect on HIV-1 replication in these cells. Taken together, these results demonstrate for the first time that Tat is a positive regulator of p300 expression, which in turn regulates GFAP expression, and suggest that the Tat-Egr-1-p300-GFAP axis likely contributes to Tat neurotoxicity and predisposes astrocytes to be an HIV-1 sanctuary in the CNS

An econometric evaluation framework for investment in construction safety

A growing body of empirical research has been focused on the relationship between investment and return on safety in the construction industry. However, these previous studies mainly described the accidents occurrence in terms of actual numbers, which were based on the hypothesis that when there is an investment, there will be an effect on construction safety performance and hence the number of accidents will be reduced. In reality, investment on construction safety does not guarantee in reducing the actual numbers of accident occurring in a construction project. The occurrence of accidents sometimes is out of control and indiscipline and hence remains random. Hence it presents a gap between the existing theory and the actual practice which means there is a need to develop theoretical framework that can closely model the accidents' randomness. To fill the gap existed in the previous studies, this paper presents an econometric analysis framework for evaluating the effectiveness of safety investment in construction project. The fundamental assumption is that the investment on safety can only reduce the probability of accident and the number of accidents occurring will behave as a random number in a range with some distributions, or, statistically speaking, shift the distribution of accidents. Firstly, the distribution of construction accidents will be determined by an econometric model. Then the differences in cost with and without safety risk reduction and mitigation programme will be calculated as the benefits of the investment. Individual simulations have no certainty on whether there is benefit, but by doing sufficient numbers of simulations (e.g. 10,000 or more) the distribution of return on investment (ROI) will be acquired. Detail steps for implementing the framework is provided, the results of the econometric evaluation will be made as the expected ROI and its confidence interval, due to the random nature of ROI. The framework developed in this paper will be the base and instruction for future work including using actual project data to test and validate the framework and proposing optimized safety investment models