Adel Sharkasi

Interrelationships among international stock market indices: Europe, Asia and the Americas

In this paper, we investigate the price interdependence between seven international stock markets, namely Irish, UK, Portuguese, US, Brazilian, Japanese and Hong Kong, using a new testing method, based on the wavelet transform to reconstruct the data series, as suggested by Lee [11]. We find evidence of intra-European (Irish, UK and Portuguese) market co-movements with the US market also weakly influencing the Irish market. We also find co-movement between the US and Brazilian markets and similar intra-Asian co-movements (Japanese and Hong Kong). Finally, we conclude that the circle of impact is that of the European markets (Irish, UK and Portuguese) on both American markets (US and Brazilian), with these in turn impacting on the Asian markets (Japanese and Hong Kong) which in turn influence the European markets. In summary, we find evidence for intra-continental relationships and an increase in importance of international spillover effects since the mid 1990s, while the importance of historical transmissions has decreased since the beginning of this century.

Intravenous Glutamine Enhances COX-2 Activity Giving Cardioprotection

BACKGROUND Preconditioning, a highly evolutionary conserved endogenous protective response, provides the most powerful form of anti-infarct protection known. We investigated whether acute intravenous glutamine, through an effect on cyclooxygenase (COX)-2 and heat shock protein (HSP) 72, might induce preconditioning. MATERIALS AND METHODS Male New Zealand white rabbits (n = 28) received either 0.5 g/kg glutamine in 0.9% saline or saline only in divided doses for 3 d. The large marginal branch of the left coronary was occluded for 30 min; cardiac function was assessed during 3 h of reperfusion, and infarct size was measured. 6-Keto-PGF-1alpha, nitrate, and malonaldehyde serum levels were determined. Hearts were taken from a further group of pretreated rabbits (n = 10) to assess myocardial COX-2 and HSP72 levels. RESULTS Glutamine pretreatment resulted in a 39% reduction in infarct size (30.7 +/- 2.0% versus 50.4 +/- 2.1% controls; P < 0.01). Myocardial COX-2 levels were significantly elevated with pretreatment (P < 0.05) and were mirrored by higher serum 6-keto-PGF-1alpha levels prior to ischemia (69 +/- 13 versus 18 +/- 21 pg/mL in controls, P = 0.027). There was no significant difference in myocardial HSP72 or serum nitrate levels following pretreatment, or malonaldehyde levels during reperfusion. CONCLUSIONS Glutamine pretreatment confers anti-infarct protection through up-regulation of COX-2, a key mediator of delayed preconditioning protection. Previous confirmation of its clinical safety profile at these doses suggests an acceptable strategy for inducing preconditioning for perioperative protection.

Apples and Oranges: the difference between the Reaction of the Emerging and Mature Markets to Crashes

We study here the behavior of the eigenvalues of the covariance matrices of returns for emerging and mature markets at times of crises. Our results appear to indicate that mature markets respond to crashes differently to emerging ones and that emerging markets take longer to recover than mature markets. In addition, the results appear to indicate that the second largest eigenvalue gives additional information on market movement and that a study of the behavior of the other eigenvalues may provide insight on crash dynamics.

A Study of Correlation and Entropy for Multiple Time Series

In this work we study multiple related (multivariate) time series from worldwide markets. We search for signs of coherence and/or synchronization using the main index as representative of the whole market. In order to better understand the relations between the time series we use two different techniques, entropy and variance-covariance matrices. We apply each procedure in a time dependent way to better understand the underlying dynamics of the system. We found that both methods show that world markets, regardless of their maturity status (mature or emergent), are behaving more and more alike over the last years. The simultaneous use of correlation and entropy to study multivariate time series is a promising approach in the sense that they capture different aspects of the collective system dynamics.