Aryl hydrocarbon receptor (AhR) ligands such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and metals, such as mercury (Hg(2+)), are environmental co-contaminants and their molecular interaction may disrupt the coordinated regulation of the carcinogen-activating enzyme cytochrome P450 1A1 (CYP1A1). Therefore, we examined the effect of co-exposure to Hg(2+) and TCDD on the expression of the CYP1A1 in HepG2 cells. Our results showed that Hg(2+) significantly inhibited the TCDD-mediated induction of CYP1A1 at the mRNA, protein, and catalytic activity levels. At the transcriptional level, co-exposure to Hg(2+) and TCDD significantly decreased the TCDD-mediated induction of AhR-dependent luciferase reporter gene expression. Moreover, Hg(2+) did not affect CYP1A1 mRNA stability, while decreasing its protein half-life, suggesting the involvement of a posttranslational mechanism. Importantly, Hg(2+) increased the expression of heme oxygenase-1 (HO-1), a rate limiting enzyme in heme degradation, which coincided with further decrease in the CYP1A1 catalytic activity levels. Upon using a competitive HO-1 inhibitor, tin mesoporphyrin, heme precursor, hemin, or transfecting the HepG2 cells with siRNA for HO-1 there was a partial restoration of the inhibition of TCDD-mediated induction of CYP1A1 catalytic activity. In conclusion, we demonstrate that Hg(2+) down-regulates the expression of CYP1A1 at the transcriptional and posttranslational levels in HepG2 cells. In addition, HO-1 is involved in the modulation of CYP1A1 at the posttranslational level.

Positioning systems are one of the key elements required by location-based services (LBS). As global positioning system (GPS) was never intended for indoor environments, indoor positioning systems based on wireless local area networks (WLAN) have been proposed as a viable solution. RADAR algorithm is one of the famous indoor positioning techniques. It uses a database of predetermined fingerprints for selected locations to estimate the location of a mobile user in the signal space. Another new proposed algorithm named the Enhanced Fingerprint (EFP) uses the same principle as RADAR algorithm but with more than one fingerprint per location. In this paper we investigated the location fingerprint based algorithms by taking RADAR and EFP with more details. We evaluated these two algorithms in terms of accuracy, reliability and computation time. Experiment results show that the EFP algorithm gains 1.82 m of accuracy over RADAR algorithm, while the last one saves 75% of computation time. We found that EFP algorithm is more consistent with varying number of training samples.

A web-based online job application has become the most useful tool to access the information about the applicant, and the applicant information is accessible at the press of

a button immediately. Graduates need to work hard to get jobs that may require cost and time. Thus this study proposal to model requirement of UUM Alumni Online Jobs that provide a flexible way to access jobs. The requirement model for the alumni students would provides the alumni with the capability to input, search and receive information of jobs via the online services.

We consider a differentiated duopoly where firms invest in research and development (R&D) to reduce their production cost. The objective of this study is to derive and compare Bertrand and Cournot equilibria, and then examine the robustness of the literature's results, especially those of Qiu (1997). We find that The main results of this study are as follows: (a) Bertrand competition is more efficient if R&D productivity is low, industry spillovers are weak, or products are very different. (b) Cournot competition is more efficient if R&D productivity is high and R&D spillovers and products' degree of substitutability are not very small. (c) Cournot competition may lead to higher Outputs, higher consumer surpluses and lower prices, provided that R&D productivity is very high and spillovers and degree of substitutability of firms' products are moderate to high, (d) Cournot competition results in higher R&D Investments compared to Bertrand's. These results show that the relative efficiencies of Bertrand and Cournot equilibria are sensitive to the suggested specifications, and hence far from being robust.

We consider a differentiated duopoly where firms invest in research and development (R&D) to reduce their production cost. We show that if the firms play a one stage game, i.e., they choose R&D and price (in Bertrand game) or quantity (in Cournot game)at the same time, then the usual result stating that Bertrand competition is more efficient than Cournot competition still holds.

Using an infinite-horizon two-player differential game, we derive and compare Bertrand and Cournot equilibria for a differentiated duopoly engaging in the process of R&D competition. The main findings of this study are as follows. First, Bertrand competition is more efficient if either R&D productivity is low or products are very different. Second, Cournot competition is more efficient provided that R&D productivity is high, products are close substitutes, and spillovers are not close to zero. This last result is different from what has been obtained in the literature. Hence, this shows that considering a dynamic model and more general investment costs does have an impact on the efficiency results.

Objective: The present study investigates the effects of alprazolam (ALP) and nifedipine alone or in combination on behavior and on g-aminobutyric acid (GABA) levels, in discrete brain regions of albino rats.

Methods: The anxiolytic effect was studied using a plus maze model and brain levels of GABA were measured using high performance liquid chromatography. Four acute treatment groups of rats were used. In the first they were treated with 1% Tween 80 (1ml/kg), in the second with nifedipine (10mg/kg), in the third with ALP (2mg/kg) and in the fourth with ALP in addition to nifedipine in the respective doses. The work was carried out at the Faculty of Pharmacy of Al-Fateh University, Tripoli, Libya in the first half of 2002.

Results: The results indicate that the anxiolytic effect of ALP was not modified by nifedipine. Nifedipine by itself significantly decreased the motor activity (decrease in total lines crossed), this effect was apparently antagonized by ALP. Alprazolam administration produced an increase of GABA levels in cerebellum and striatum and a decrease in the brain stem. Nifedipine per-se had no effect on GABA levels in the brain stem but it partially antagonized ALP-induced inhibitory effect on GABA in this region. Alprazolam significantly increased GABA levels in the striatum, while nifedipine alone had no effect on neurotransmitter levels and did not modify the ALP effect in this brain region. Alprazolam or nifedipine had no significant effect on GABA levels in midbrain, cerebral cortex and whole brain. There were no significant changes in GABA levels in midbrain and whole brain with drug combination. However, the combination decreased GABA levels significantly in the cerebral cortex.

Conclusion: It may be concluded that, the anxiolytic effect of ALP possibly occurs through changes in brain GABA levels (an increase in cerebellum and striatum with a decrease in brain stem). The effect was not modified by nifedipine which per se had no affect on GABA levels in any brain area. The significant decrease in GABA levels in cerebral cortex by ALP-nifedipine combination may be due to the mutual closure of calcium channel (mentioned in literature) resulting in inhibition of the EAA-ergic input to GABA-ergic neuron.