Stock Market Volatility and Weak-form Efficiency: Evidence from an Emerging Market

There exists a vast literature on modeling and estimating aggregate stock market volatility over the past decade [e.g., Choudhry (1996); Mecagni and Sourial (1999) and Kabir, et al. (2000)]. Motivations for undertaking this exercise have been varied. Many value-at-risk models for measuring market risk require the estimation of volatility parameter. Portfolio diversifications and hedging strategies also require information on volatility as a key input. Volatility is defined as tendency of the assets price to fluctuate either up or down. Increased volatility is perceived as indicating a rise in financial risk which can adversely affect investor assets and wealth. It is observed that when stock market exhibit increased volatility there is a tendency on part of the investors to lose confidence in the market and they tend to exit the market. The nexus between volatility and economic fundamentals is still a moot point. Stock prices reflect information and quicker they are in absorbing accurately new information, more efficient is the stock market in allocating resources. The increase in volatility can be attributed to absorption of new information about economic fundamentals or some expectations about them. This kind of volatility is not harmful as there is no social cost associated with it. But if increased volatility is not explained by the level indicated by the fundamental economic factors, there is a tendency that stocks will be mispriced and this will lead to misallocation of resources [Karmaka (2006)]

Anterior Cage Fixation in Spinal Injuries

Methods:  The study comprised 121 patients (98 men and 23 women) between ages 15-70 years with one spinal fracture with two or three column destruction, who underwent with expandable cage placement, between January 2005 to January 2009. Neurological status was classified using American Spinal Injury Association (ASIA) impairment scale and motor index. The fusion status and spine alignment were examined by radiological imaging. Results:  All patients in this study achieved solid fusion with significant neurologic improvement. Mean follow up time was 6 months. Neurologic status in 41 patients (pre op: ASIA-E post op-unchanged). 30 patients (pre-op: ASIA-D, post-op improved to ASIA-E). 6 patients (pre op: ASIA-B, 2 patients improved to ASIA-D and 5 patients improved to ASIA-D). Pain improved in all case and sensations were last to recover. Conclusion:  The TMC is an effective adjunct in restoring and maintaining sagittal plane alignment after thoracolumbar vertebrectomy to achieve canal decompression and in this context it provides an effective method for anterior column reconstruction. It has been found to be a rapid and safe procedure for lumber spine fusion, with a high fusion rate and clinical success with rare serious complications. Key words:  Thoracolumbar spinal trauma, Titanium Mesh Cage, Anterior Column Reconstruction of spine, Spinal stability

Analytic Solution for the Drainage of Sisko Fluid Film Down a Vertical Belt

This paper deals with the drainage of Sisko fluid film down a vertical belt. It provides an approximate solution of the resulting non-linear and inhomogeneous ordinary differential equation using perturbation method (PM) and Adomian decomposition method (ADM). Comparison of the results obtained by both methods demonstrate that these series solutions are strictly identical but ADM is easy to compute and can be extended to any higher order. The important physical quantities like velocity profile, volume flow rate, average film velocity, shear stress, force exerted by the fluid film and vorticity vector are derived. The effects of fluid behaviour index, Stokes number and Sisko fluid parameter on some of these physical quantities are observed. Furthermore, we also made a comparison between the Sisko fluid film and Newtonian fluid film

Strengthening of Continuous SCC Hollow Beams under Shear Stresses Using Warped CFRP Strips

The present paper is deal with shear strength evaluation of continuous self-compacting concrete hollow beams containing internal concrete ribs and externally strengthening by carbon fiber strips (CFRP). Six full-scale beam specimens and series of control specimens were tested. The adopted variables in this study are the number of internal concrete ribs and external U-shape CFRP strips at (45º). Experimental results show that the shear failure was the dominant failure for all tested beams. The cracking and ultimate load are reduced by about (19.6-30.6%) for the hollow beams specimens contains five and three ribs respectively compared with the reference beam. The ultimate load was increased for about (50.7%) for five internal ribs hollow beams strengthened by CFRP strips in compared with the same beams but without strengthening.  While, the ultimate load was increased for about (33.46%), for beam specimen who has three internal ribs and strengthened by CFRP, in comparison with the same beams but without strengthening. Keywords: CFRP Strips, Shear, Continuous Beam, Self-Compacting Concrete, Hollow, Rib

Flexural behavior of sustainable reactive powder concrete bubbled slab flooring elements

Voided slabs are reinforced concrete slabs in which voids allow to reduce the amount of concrete. The bubbled deck slab is a new and sustainable biaxial floor system to be used as a self-supporting concrete floor. The use of voided slabs leads to decrease the consumption of materials and improve the insulation properties for enhancing the objectives of sustainability. This study presents an investigation into the flexural behavior of sustainable Reactive Powder Concrete RPC bubbled slab flooring elements. Six one-way slabs were cast and tested up to the failure. The adopted variables in this study are: the volumetric ratio of steel fibers, type of slab; bubbled or solid, placing of reinforcement and thickness of slab. The effect of each variable on the ultimate load, deflection and strain has been discussed. The results show that increasing the percent of steel fibers from 1% to 2% in solid and bubbled slabs decreases the deflection by (18.75%) and (50%) respectively. As well as, the deflection increases by (41%) for bubbled slab compared to the solid slab. The slabs reinforced with top and bottom steel meshes show less deflection than slabs reinforced by only bottom steel mesh

On the analytic solution for the steady drainage of magnetohydrodynamic (MHD) Sisko fluid film down a vertical belt

This paper presents an analytic study for the steady drainage of magnetohydrodynamic (MHD) Sisko fluid film down a vertical belt. The fluid film is assumed to be electrically conducting in the presence of a uniform transverse magnetic field. An analytic solution for the resulting non linear ordinary differential equation is obtained using the Adomian decomposition method. The effects of various available parameters especially the Hartmann number are observed on the velocity profile, shear stress and vorticity vector to get a physical insight of the problem. Furthermore, the shear thinning and shear thickening characteristics of the Sisko fluid are discussed. The physical quantities discussed for the Sisko fluid film have also been discussed for the Newtonian fluid film and comparison between them made

Effectiveness of Connections Type on Vibration Response of Steel Beam

In a steel structure, choosing the connections type are one of the most important parameters in design consideration. How a connection type affects the vibration of steel beams has been investigated in this paper. The most effective connection type in reducing beam vibration has been highlighted. The study was conducted using different finite element models to simulate each connection type. Firstly, the model was validated by comparing its results with the results obtained by the analytical approach. In the numerical model, a linear frequency analysis was performed to determine beam natural frequency, then it has been compared with the corresponding value obtained by the Euler-Bernoulli approximations for simply supported beams. After that, two analysis procedures have been executed, steady-state analysis and transient analysis. In the steady-state analysis, a harmonic load with different frequencies was applied to the beam mid-span, while an impulsive load has been applied in the transient analysis. The results indicate that the deflection could be reduced by 72%, furthermore steady vibration of the beam can be reduced by 81% with using one of the moment connections instead of the traditional shear connection