Market Volatility Transmission and Central Banking: What Happened during the Subprime Crisis?

Kamel Malik Bensafta,Gervasio Semedo 한국국제경제학회 2014 International Economic Journal Vol.28 No.4

We examine market volatility spillover during calm and crisis periods. First, we define endogenous and exogenous market volatility: endogenous volatility refers to the early part of uncertainty in the market, while, exogenous volatility is not fully anticipated and occurs as a result of decisions taken by actors and institutions. Endogenous volatility is captured by the mean of the GARCH-type process. We compare market reaction to central banking for two states: outside the subprime crisis and during the subprime crisis. We evaluate the effectiveness of central banking during the crisis. We used a Multivariate GARCH model with structural breaks in variance. Our main findings confirm the American market's impact on European markets, and changes in cross-market spillover during the crisis. The results show the effect of communications, meeting days and policy decisions of the Fed on world markets.

Response of Commercial Cotton Cultivars to Fusarium solani

Kamel A. Abd-Elsalam,Moawad R. Omar,Abdel-Rheem El-Samawaty,Aly A. Aly 한국식물병리학회 2007 Plant Pathology Journal Vol.23 No.2

Twenty-nine isolates of Fusarium solani, originally isolated from diseased cotton roots in Egypt, were evaluated for their ability to cause symptoms on four genetically diverse cotton cultivars. Analysis of variance showed highly significant variance among cultivars, and isolates as well as the isolate × genotype interactions were highly significant (p < 0.0001). Although most isolates showed intermediate pathogenicity, there were two groups of isolates that showed significant differences in pathogenicity on all four cultivars. None of the cultivars were found to be immune to any of the isolates. On all cultivars, there were strong significant positive correlations between dry weight and each of preemergence damping-off, survival, and plant height. Considering 75% similarity in virulence, two groups comprising a total of 29 isolates were recognized. Ninety-three percent of the isolates have the same pathogenicity patterns with consistently low pathogenicity, and narrow diversity of virulence. Isolates Fs4 and Fs5 shared the same distinct overall virulence spectrum with consistently high pathogenicity. There was no clear-cut relationship between virulence of the isolates based on reaction pattern on 4 cultivars and each of host genotype, previous crop, and geographic origin.

Biophysical properties of PPF/HA nanocomposites reinforced with natural bone powder

Kamel, Nagwa A.,Mansour, Samia H.,Abd-El-Messieh, Salwa L.,Khalil, Wafaa A.,Abd-El Nour, Kamal N. Techno-Press 2015 Advances in materials research Vol.4 No.3

Biodegredable and injectable nanocomposites based on polypropylene fumarate (PPF) as unsaturated polyester were prepared. The investigated polyester was crosslinked with three different monomers namely N-vinyl pyrrolidone (NVP), methyl methacrylate (MMA) and a mixture of NVP and MMA (1:1 weight ratio) and was filled with 45 wt% of hydroxyapatite (HA) incorporated with different concentrations of chemically treated natural bone powder (NBP) (5, 10 and 15 wt%) in order to be used in treatment of orthopedics bone diseases and fractures. The nanocomposites immersed in the simulated body fluid (SBF) for 30 days, after the period of immersion in-vitro bioactivity of the nanocomposites was studied through Fourier transform infrared (FTIR), scanning electron microscope (SEM), energy dispersive X-ray (EDX) in addition to dielectric measurements. The degradation time of immersed samples and the change in the pH of the SBF were studied during the period of immersion.

An accelerated sequential sampling for estimating the reliability of N-parallel systems

Kamel Rekab,Yuan Cheng 한국신뢰성학회 2013 International Journal of Reliability and Applicati Vol.14 No.2

The problem of designing an experiment to estimate the reliability of a system that has N subsystems connected in series where each subsystem n has n Tn components connected in parallel is investigated both theoretically and by simulation. An accelerated sampling sheme is introduced. It is shown that the accelerated sampling scheme is asymptotically optimal as the total number of units goes to infinity. Numerical comparisons for a system that has two subsystems connected in series where each subsystem has two components connected in parallel are also given. They indicate that the accelerated sampling scheme performs better than the batch sequential sampling scheme and is nearly optimal.

Stability in nonlinear neutral Levin-Nohel integro-differential equations

Kamel Ali Khelil,Abdelouaheb Ardjouni,Ahcene Djoudi 강원경기수학회 2017 한국수학논문집 Vol.25 No.3

In this paper we use the Krasnoselskii-Burton's fixed point theorem to obtain asymptotic stability and stability results about the zero solution for the following nonlinear neutral Levin-Nohel integro-differential equation $$ x^{\prime }(t)+\int_{t-\tau (t)}^{t}a(t,s)g\left( x(s)\right) ds+c(t)x^{\prime }(t-\tau (t))=0. $$ The results obtained here extend the work of Mesmouli, Ardjouni and Djoudi [20].

Decomposition method for solving nonlinear integro-differential equations

Kamel Al-Khaled,Fathi Allan 한국전산응용수학회 2005 Journal of applied mathematics & informatics Vol.19 No.1-2

This paper outlines a reliable strategy for solving nonlinear Volterra-Fredholm integro-differential equations. The modified form of Adomian decomposition method is found to be fast and accurate. Numerical examples are presented to illustrate the accuracy of the method.

Hygrothermal effects on the behavior of reinforced-concrete beams strengthened by bonded composite laminate plates

Kamel Antar,Khaled Amara,Samir Benyoucef,Mokhtar Bouazza,Mokhtar Ellali 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.69 No.3

The purpose of this paper is to investigate the hygrothermal effects on the behavior of reinforced-concrete beams strengthened by bonded composite laminate plates (n/90 m)s. This work is based on a simple theoretical model to estimate the interfacial stresses developed between the concrete beam and the composite with taking into account the hygrothermal effect. Fibre orientation angle effects of number of 90° layers and effects of plate thickness and length on the distributions of interfacial stress in the concrete beams reinforced with composite plates have also been studied.

Does intrauterine injection of low-molecular-weight heparin improve the clinical pregnancy rate in intracytoplasmic sperm injection?

Kamel, Ahmed Mohamed,El-Faissal, Yahia,Aboulghar, Mona,Mansour, Ragaa,Serour, Gamal I,Aboulghar, Mohamed The Korean Society for Reproductive Medicine 2016 Clinical and Experimental Reproductive Medicine Vol.43 No.4

Objective: Heparin can modulate proteins, and influence processes involved in implantation and trophoblastic development. This study aimed to assess the improvement of clinical pregnancy and implantation rates after local intrauterine injection of low-molecular-weight heparin (LMWH) in patients undergoing intracytoplasmic sperm injection (ICSI). Methods: A randomised case/control design was followed in women scheduled for ICSI. The study arm was injected with intrauterine LMWH during mock embryo transfer immediately following the ovum pickup procedure, while the control arm was given an intrauterine injection with a similar volume of tissue culture media. Side effects, the clinical pregnancy rate, and the implantation rate were recorded. Results: The pregnancy rate was acceptable (33.9%) in the LMWH arm with no significant reported side effects, confirming the safety of the intervention. No statistically significant differences were found in the clinical pregnancy and implantation rates between both groups (p= 0.182 and p= 0.096, respectively). The odds ratio of being pregnant after intrauterine injection with LMWH compared to the control group was 0.572 (95% confidence interval [CI], 0.27-1.22), while the risk ratio was 0.717 (95% CI, 0.46-1.13; p= 0.146). No statistical significance was found between the two groups in other factors affecting implantation, such as day of transfer (p= 0.726), number of embryos transferred (p= 0.362), or embryo quality. Conclusion: Intrauterine injection of LMWH is a safe intervention, but the dose used in this study failed to improve the outcome of ICSI. Based on its safety, further research involving modification of the dosage and/or the timing of administration could result in improved ICSI success rates.

Sliding Mode Control Based DTC of Sensorless Parallel-Connected Two Five-Phase PMSM Drive System

Kamel, Tounsi,Abdelkader, Djahbar,Said, Barkat,Al-Hitmi, M.,Iqbal, Atif The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.3

This paper presents a sensorless direct torque control (DTC) combined with sliding mode approach (SM) and space vector modulation (SVM) to achieve mainly a high performance and reduce torque and flux ripples of a parallel-connected two five-phase permanent magnet synchronous machine (PMSM) drive system. In order to increase the proposed drive robustness and decrease its complexity and cost, the rotor speeds, rotor positions, fluxes as well as torques are estimated by using a sliding mode observer (SMO) scheme. The effectiveness of the proposed sliding mode observer in conjunction with the sliding mode control based DTC is confirmed through the application of different load torques for wide speed range operation. Comparison between sliding mode control and proportional integral (PI) control based DTC of the proposed two-motor drive is provided. The obtained speeds, torques and fluxes responses follow their references; even in low and reverse speed operations, load torques changes, and machines parameters variations. Simulation results confirm also that, the ripples of the torques and fluxes are reduced more than 3.33% and 16.66 %, respectively, and the speed overshoots and speed drops are reduced about 99.85% and 92.24%, respectively.

TECHNICAL EFFICIENCY DETERMINANTS OF THE TUNISIAN MANUFACTURING INDUSTRY: STOCHASTIC PRODUCTION FRONTIERS ESTIMATES ON PANEL DATA

KAMEL HELALI,MAHA KALAI 중앙대학교 경제연구소 2015 Journal of Economic Development Vol.40 No.2

In this paper, we analyze the development of technical efficiency in the Tunisian manufacturing sector using advanced analysis methods. The technical efficiency of the industrial sectors is measured on the basis of panel data through the bias of a classical approach and a Bayesian one, which makes the inefficiency terms change over time. This exercise helps to assess the robustness of the estimated technical efficiency compared to the choice of the estimation technique. The mean efficiency score is found to be of 77 percent and there is no evidence of a continuous increase in efficiency.