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Free Space Optical (FSO) communication systems are gaining popularity due to its tremendous speed, advanced capacity, cost effectiveness, secure and easy to deploy wireless networks. This technology has proven an effective choice for last mile applications and hard to reach areas where deployment of optical fibre links is not feasible. But FSO link is highly weather dependent and as signal passes through the atmospheric channel, the main impairments are the atmospheric turbulence, which induce fading and deteriorate the system performance. Delhi has a great potential for FSO communication because of its clear skies. Since there is no analysis for weather condition found in Delhi, this work provides analysis of typical Delhi weather condition ranging from heavy to light rain, fog and clear sky. The performance of FSO link is analysed in terms of attenuation and link length margin under different weather condition. The results are concluded to identify which atmospheric condition influences more on FSO link performance. [ABSTRACT FROM AUTHOR]

Free Space Optical (FSO) communication offers a promising technology for future high speed networks by providing huge transmission bandwidth, light weight, small size, low cost, low power and license free deployment as compared to the present radio frequency systems. Since in FSO communication, the atmosphere is used as a channel, atmospheric turbulence effects cause fading and misalignment of signal at the receiver and deteriorate the Bit Error Rate (BER) performance. This paper is focused on analyzing the FSO communication system performance in Delhi by modeling FSO communication system using basic Wavelength Division Multiplexing (WDM) technique with optimizing several system parameters in different turbulent environments such as fog and rain. Performance is analyzed in terms of Signal-to-Noise Ratio (SNR), received optical power and BER for different meteorological effects at data rate of 2.5 Gbps, 5 Gbps and 15 Gbps. From the results, it is concluded that the quality of received signal can be improved with priority-based optimization of parameters that increases link range up to 115 km in clear weather condition at 15 Gbps. [ABSTRACT FROM AUTHOR]

Bacteria sense and respond to environmental cues to control important developmental processes. Two widely conserved and important strategies that bacteria employ to sense changes in population density and local environmental conditions are quorum sensing (QS) and cyclic di-GMP (c-di-GMP) signaling, respectively. The importance of these pathways in controlling a broad variety of functions, including virulence, biofilm formation, and motility, has been recognized in many species. Recent research has shown that these pathways are intricately intertwined. Here we review the regulatory connections between QS and c-di-GMP signaling. We propose that the integration of QS with c-di-GMP allows bacteria to assimilate information about the local bacterial population density with other physicochemical environmental signals within the broader c-di-GMP signaling network. [ABSTRACT FROM AUTHOR]