QScience Connect - Volume 2013, Issue 1

In this paper an inhomogeneous beam with a damping distributed along the length is considered. The beam is clamped at both ends and is assumed to vibrate in a transverse direction only. The total energy of the system at any time t is estimated. Finally, an explicit form of exponential energy decay is obtained. Hence, the uniform stabilization of the system is achieved.

Background: The demography of Copts in Egypt is subject to an intense debate in the context of a dearth of analytical studies on this community. Our objective was to estimate the size of the Coptic community in Egypt, map its geographical clustering, and describe demographic, socioeconomic, and health-associated indicators. Methods: We conducted descriptive and Kulldorff spatial scan statistics analyses using the 2008 Egypt Demogra Read More

In this paper, the differential equation of a vertically falling non-spherical particle in incompressible Newtonian media is solved by homotopy analysis method (HAM). The results are analyzed using graphs and comparison tables.

The (G′/G, 1/G)-expansion method is one of the most direct and effective methods for obtaining exact traveling wave solutions of nonlinear partial differential equations (PDEs). In this paper, we construct exact travelling wave solutions of nonlinear evolution equations in mathematical physics via generalized Zakharov-Kuznetsov (ZK), modified Zakharov-Kuznetsov and Sharma–Tasso–Olver (STO) equations by (G′/G, 1/G)-expansion meth Read More

As part of the biodiversity surveys conducted by the Department of Biodiversity at the Qatar Environment and Energy Research Institute (QEERI), we can report the presence of Scaurus puncticollis Solier, 1838 in Qatar, and confirm the first record for the tribe Scaurini Billberg, 1820 in the country. We found two living specimens and remains of a third one distributed over the year (February, April and October) in three different locations of t Read More

We present a geometric argument that explains why some systems having vanishing largest Lyapunov exponent have underlying dynamic aspects which can be effectively described by the Tsallis entropy. We rely on a comparison of the generalised additivity of the Tsallis entropy versus the ordinary additivity of the BGS entropy. We translate this comparison, in metric terms, by using an effective hyperbolic metric on the configuration/phas Read More

The equations of generalized thermoelastic diffusion with four relaxation times are given. The variational principle is derived. Using Laplace transforms, a uniqueness theorem for these equations is proved. Also, a reciprocity theorem is obtained.

We report the discovery of a gecko species, the Persian leaf-toed gecko Hemidactylus persicus Anderson, 1872 (Gekkonidae) in Qatar, found on Halul Island. According to the Qatar National Biodiversity Surveys and the available international literature H. persicus was not previously recorded in Qatar. Its known range covers the north east of the Arabian Peninsula, Bahrain, the United Arab Emirates, and south western Asia. Our findings brid Read More

Ground Granulated Blast Furnace Slag (GGBFS) is a byproduct in the manufacture of pig iron, which contains almost the same chemical compositions as cement. As a new method for activation of GGBFS, a simple sonochemical route was developed to synthesize nanoparticles of GGBFS. Chemical composition of the GGBFS sample was characterized using X-ray fluorescence (XRF). Crystallinity, morphology and reactivity of the GGBFS sa Read More

Background: This study aimed to synthesize some 2′, 3′, 4′-trichlorophenyl chalcones [(E)-1-(2, 3, 4-trichlorophenyl)-3-(substituted phenyl)-2-propen-1-ones] using solvent-free sulfated Titania catalyzed aldol condensation between 2, 3, 4-trichloroacetophenone and substituted benzaldehydes under microwave irradiation. To characterize these chalcones using analytical, physical and spectroscopic data and also to study their the spectral c Read More

This study examines the environmental factors affecting the density of the exploited giant land snail species, Archachatina marginata, Achatina fulica and Limicolaria flammea in the Dassa-Zoumè district of Benin. Thirty plots of 30 m × 30 m were laid out, within four vegetation types (fallows, forest, woodlands and wood savannah). Inside each plot the numbers of each giant land snail species were counted, and soil characteristics were m Read More

Effect of thermal conductivity on gravitational instability of quantum plasma in the presence of fine dust particles has been investigated. Following the linearized stability theory and normal mode analysis, the paper established a general dispersion relation of the problem. Modified condition of Jeans gravitational instability is obtained due to quantum effect. Numerical calculations were performed to find the effect of each parameter on the Read More

This paper describes the optical limiting performance of 2D ZnO nanoflakes and plates synthesized through a simple wet chemical method. Scanning electron microscopic imaging of these nanostructures revealed the shape evolution from the nanoflakes to nanoplates as the growth duration increased from 11 h to 18 h. The nonlinear absorption is studied using open aperture Z scan technique. The process behind the nonlinear absorption is Read More

The Gulf sand gecko (Pseudoceramodactylus khobarensis Haas, 1957) is a nocturnal gecko endemic to the Arabian Gulf countries. In this study we report the presence of this species in Qatar for the first time. Our findings bridge one of the current geographic gaps in the known distribution range of this species. In Qatar, the species has been found on the mainland and on two islands occupying coastal salty habitats with shrubs. The islands ar Read More

By integrating Radio Frequency Identification (RFID) technology with Wireless Sensor Networks (WSN), it is feasible to route RFID data from readers and RFID enhanced wireless sensor nodes (WSN) into base-stations through existing WSN clustering protocols. WSNs for reducing energy consumption and improving stability period can use clustering algorithms. Clustering sensor nodes are a useful topology control technique, but these algorithm Read More

A characteristic property of esters is that, they undergo both oxidation and hydrolysis under similar conditions. Furthermore, the product of each process is an aldehyde (the product of hydrolysis is alcohol, which in turn undergoes oxidation to give an aldehyde). It is, therefore, difficult to find out which process is operative. The kinetics of the reaction offers an opportunity to resolve this uncertainty. This method is illustrated in this articl Read More

Minerals have a profound impact on reproduction. The relations between estradiol-17β (E2) and blood mineral levels have been studied mainly in human and rats, but not in quail. Therefore, the aim of this study was to test the effect of E2 on serum mineral concentrations in Japanese quail (Coturnix japonica). The study was conducted at the Seljuk University animal farm thirteen week old female Japanese quails (n = 33) were housed in ca Read More

Copper(II) complexes with novel chelator-type nucleosides: histidine modified 2′-deoxyriboadenosine (N-[(9-β-D-2′-deoxyribofuranosylpurin-6-yl)-carbamoyl]histidine) and histamine modified 2′-deoxyriboadenosine (N-[(9-beta-D-2′-deoxyribofuranosylpurin-6-yl)-carbamoyl]histamine) were studied by potentiometric and spectroscopic (UV–VIS, CD, EPR) techniques. A histidine or histamine residue was inserted in the purine part of a nucle Read More

The present work investigates forced convective heat transfer characteristics of alumina-water nanofluids in a turbulent flow regime. Nanofluids are dilute colloidal suspensions with nano-sized particles ( < 100 nm) dispersed in a basefluid. The thermal conductivity values are measured by a steady state method, using a guarded hot plate (GHP) apparatus customized for liquids. The forced convective heat transfer characteristics are eval Read More

Rod-shaped antimony sulphoiodide (SbSI) crystals were grown by utilizing elemental components of the compound. The material was characterized by X-ray diffraction (XRD), Raman and surface morphology by SEM. Electrical conductivity was measured on the pallets of powdered SbSI by the four-probe technique in the temperature range of 4–300K, and by the two-probe technique in the temperature range of 300–550K. SbSI shows semicon Read More