Wireless Networks Simulation with Assessment in PT Software

Teaching and learning more theoretical subjects, such as wireless networks, where higher level of students imagination is necessary to understand advanced topics can be positively supported trough a technique called practical learning. Students can more easily understand and adapt the information from the subject, when they can visually see how it really works. Teachers can present the subject using animations and practical examples, rather than just talking about theory facts. This paper presents the features of a practical learning tool called Packet Tracer - a computer networks simulation also used for wireless network s , which is freely available for all Cisco Networking Academy students . Packet Tracer includes features for assessment task authoring with automated scoring and reporting. We believe that this analysis helpful for wireless network students as well as faculties

X-ray emission from O-type stars : DH Cep and HD 97434

We present X-ray emission characteristics of the massive O-type stars DH Cep and HD 97434 using archival XMM-Newton observations. There is no convincing evidence for short term variability in the X-ray intensity during the observations. However, the analysis of their spectra reveals X-ray structure being consistent with two-temperature plasma model. The hydrogen column densities derived from X-ray spectra of DH Cep and HD 97434 are in agreement with the reddening measurements for their corresponding host clusters NGC 7380 and Trumpler 18, indicating that the absorption by stellar wind is negligible. The X-ray emission from these hot stars is interpreted in terms of the standard instability-driven wind shock model.Comment: 13 pages ; 2 figures; 2 tables (Accepted for publication in New Astronomy

Impedance Spectroscopic Investigation of the Degraded Dye-Sensitized Solar Cell due to Ageing

This paper investigates the effect of ageing on the performance of dye-sensitized solar cells (DSCs). The electrical characterization of fresh and degraded DSCs is done under AM1.5G spectrum and the current density-voltage (J-V) characteristics are analyzed. Short circuit current density (JSC) decreases significantly whereas a noticeable increase in open circuit voltage is observed. These results have been further investigated electroanalytically using electrochemical impedance spectroscopy (EIS). An increase in net resistance results in a lower JSC for the degraded DSC. This decrease in current is mainly due to degradation of TiO2-dye interface, which is observed from light and dark J-V characteristics and is further confirmed by EIS measurements. A reduction in the chemical capacitance of the degraded DSC is observed, which is responsible for the shifting of Fermi level with respect to conduction band edge that further results in an increase of open circuit voltage for the degraded DSC. It is also confirmed from EIS that the degradation leads to a better contact formation between the electrolyte and Pt electrode, which improves the fill factor of the DSC. But the recombination throughout the DSC is found to increase along with degradation. This study suggests that the DSC should be used under low illumination conditions and around room temperature for a longer life

Improvement of faba bean (Vicia faba L.) yield and quality through biotechnological approach: A review

Faba bean (Vicia faba L.), an old-world grain legume, is grown approximately in 3 m/ha area world-wide from temperate, tropical to hot arid conditions. It is such a wonderful legume that it can excel even under adverse soil conditions; acidic or saline alkaline (pH 4.5 to 9.0). In favourable conditions, it gives very high yields, but low yield may result from biotic and abiotic stress. In India, it is still treated as minor legume. Genetic transformation based on Agrobacteria is possible. Several random amplified polymorphic DNA (RAPD) markers linked to a gene determining hypersensitive resistance to race 1 of the rust (Uromyces viciae-fabae) have been reported. Molecular breeding for resistance to broomrape, Ascochyta blight, rust, and chocolate spot have been obtained. The use of marker assisted selection (MAS) can complement conventional breeding by speeding up the selection of desirable traits and increasing selection efficiency. Recently, markers linked to a gene controlling growth habit or to select against traits affecting the nutritional value of seeds have also been reported. Lack of suitable cultivar can be easily overcome by application of modern tools and techniques. Several in-vitro techniques would be very useful for faba bean breeding. New techniques such as protoplast fusion, regeneration, and embryo-rescue assisted interspecific crossing could probably be introduced to V. faba L. to improve yield and quality. This review work examines the role of various techniques with reference to faba bean improvement.Key words: Vicia faba, faba bean, grain quality, resistance breeding, nitrogen fixation, zero tannin

Evolution of the Type IIb SN 2011fu

The UBVRI photometric follow-up of SN 2011fu has been initiated a few days after the explosion, shows a rise followed by steep decay in all bands and shares properties very similar to that seen in case of SN 1993J, with a possible detection of the adiabatic cooling phase at very early epochs. The spectral modeling performed with SYNOW suggests that the early-phase line velocities for H and Fe ii features were ~ 16000 km s−1 and ~ 14000 km s−1, respectively. Studies of rare class of type IIb SNe are important to understand the evolution of the possible progenitors of core-collapse SNe in more details