3,044 research outputs found
Evolution of worldwide stock markets, correlation structure and correlation based graphs
We investigate the daily correlation present among market indices of stock
exchanges located all over the world in the time period Jan 1996 - Jul 2009. We
discover that the correlation among market indices presents both a fast and a
slow dynamics. The slow dynamics reflects the development and consolidation of
globalization. The fast dynamics is associated with critical events that
originate in a specific country or region of the world and rapidly affect the
global system. We provide evidence that the short term timescale of correlation
among market indices is less than 3 trading months (about 60 trading days). The
average values of the non diagonal elements of the correlation matrix,
correlation based graphs and the spectral properties of the largest eigenvalues
and eigenvectors of the correlation matrix are carrying information about the
fast and slow dynamics of correlation of market indices. We introduce a measure
of mutual information based on link co-occurrence in networks, in order to
detect the fast dynamics of successive changes of correlation based graphs in a
quantitative way.Comment: 8 pages, 11 figure
Inhibition of Arterial Allograft Intimal Hyperplasia Using Recipient Dendritic Cells Pretreated with B7 Antisense Peptide
Background. Low expression or absence of dendritic cell (DC) surface B7 molecules can induce immune tolerance or hyporesponse. Whether DCs could induce indirect allogeneic-specific cross-tolerance or hyporesponse to recipient T cells remains unclear. Methods. Generated from C3H/He mice bone marrow cells pulsed with donor antigen from C57BL/6 mice, recipient DCs were incubated with B7 antisense peptide (B7AP). Immune regulatory activities were examined in vitro by a series of mixed lymphocyte reactions. Murine allogeneic carotid artery orthotopic transplantation was performed from C57BL/6 to C3H/He. Recipients were given B7AP-treated DCs 7 days before transplantation. Allograft pathological analysis was done 2 months after transplantation. Results. B7AP-pretreated DCs markedly inhibited T-cell proliferation compared with untreated group. Pretreated T cells exhibited markedly reduced response to alloantigen versus third-party antigen. Pathological analysis of arterial allografts demonstrated significant reduction of intimal hyperplasia in B7-AP pretreated group versus control. Conclusion. Blockade of B7 molecules by B7AP could induce indirect allogeneic-specific hyporesponse and inhibit arterial allograft intimal hyperplasia, which may be involved in future strategies for human allograft chronic rejection
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