American University in Cairo

About: American University in Cairo is a education organization based out in Cairo, Egypt. It is known for research contribution in the topics: Population & Context (language use). The organization has 2472 authors who have published 5339 publications receiving 73741 citations.

Silicon Waveguides at the Mid-Infrared

Abstract: In this paper, we propose a detailed study of various novel waveguides made using doped silicon at the mid-infrared (MIR) range. These waveguides support a plasmonic-like mode with nanoscale confinement in the MIR. We also demonstrate a simple mechanism for tuning the plasma resonance through controlling the doping level of silicon. Moreover, the dispersion characteristics of the doped silicon devices are analyzed for different applications at the MIR region. We also investigated various phenomenon such as negative dispersion, which can be utilized for slow light and metamaterial applications, and epsilon-near-zero characteristics that can be used for extraordinary transmission. The MIR dispersion is studied thoroughly for the slot structure and the rectangular shell structure. The potential for biological and environmental sensing for the aforementioned structures is investigated as well. In addition, we demonstrated the use of the waveguide as a slow light medium; this was facilitated as the dispersion relations reached giant values in the order of $10^{5}$ at the resonance.

On the Asymptotic Power of Unit Root Tests

Abstract: Closed forms for the distribution of some conventional statistics are given as a prelude to deriving their asymptotic power functions as unit root tests. In the process, an important distinction is drawn between two classes of statistics: one which relies on deterministic normalizations and the other which uses stochastic normalizations. When the data follow a driftless autoregression, a t test (which belongs to the second class) for a unit root is found to perform better than the other tests in small to moderate effective samples.

TiO2 Nanotube-Based Dye-Sensitized Solar Cell Using New Photosensitizer with Enhanced Open-Circuit Voltage and Fill Factor

Abstract: We report the synthesis and characterization of a high molar extinction coefficient ruthenium complex sensitizer (Ru (6,6′-(COOEt)2-2,2′-bpy)2(Cl)2). In conjugation with TiO2 nanotube arrays as a photoactive material and iodine/iodate redox electrolyte, we fabricated efficient dye-sensitized solar cell device showing a conversion efficiency of 3.94% measured under the air mass 1.5 global (AM1.5G) sunlight. The solar cell device showed a reasonably high open circuit voltage (0.74 V) as well as a fill factor of 0.63.