Objective:To assess the in vitro antibacterial, antifungal and cytotoxic activities of amblyone, a triterpenoid isolated from Amorphophallus campanulatus (Roxb).Methods:Disc diffusion technique was used for in vitro antibacterial and antifungal screening. Cytotoxicity was determined against brine shrimp nauplii. In addition, minimum inhibitory concentration (MIC) was determined using serial dilution technique to determine the antibacterial potency.Results:Large zones of inhibition were observed in disc diffusion antibacterial screening against four Gram-positive bacteria (Bacillus subtilis, Bacillus megaterium, Staphylococcus aureus and Streptococcus pyogenes) and six Gram-negative bacteria (Escherichia coli, Shigella dysenteriae, Shigella sonnei, Shigella flexneri, Pseudomonas aeruginosa and Salmonella typhi). The MIC values against these bacteria ranged from 8 to 64 μg/ml. In antifungal screening, the compound showed small zones of inhibition against Aspergillus flavus, Aspergillus niger and Rhizopus aryzae. Candida albicans was resistant against the compound. In the cytotoxicity determination, LC50 of the compound against brine shrimp nauplii was 13.25 μg/ml.Conclusions:These results suggest that the compound has good antibacterial activity against the tested bacteria, moderate cytotoxicity against brine shrimp nauplii and insignificant antifungal activity against the tested fungi.

No abstract

No abstract

No abstract

Context: Software projects rely on their issue tracking systems to guide maintenance activities of software developers. Bug reports submitted to the issue tracking systems carry crucial information about the nature of the crash (such as texts from users or developers and execution information about the running functions before the occurrence of a crash). Typically, big software projects receive thousands of reports every day.Objective: The aim is to reduce the time and effort required to fix bugs while improving software quality overall. Previous studies have shown that a large amount of bug reports are duplicates of previously reported ones. For example, as many as 30% of all reports in for Firefox are duplicates. Method: While there exist a wide variety of approaches to automatically detect duplicate bug reports by natural language processing, only a few approaches have considered execution information (the so-called stack traces) inside bug reports. In this paper, we propose a novel approach that automatically detects duplicate bug reports using stack traces and Hidden Markov Models. Results: When applying our approach to Firefox and GNOME datasets, we show that, for Firefox, the average recall for Rank k =1 is 59%, for Rank k=2 is 75.55%. We start reaching the 90% recall from k=10. The Mean Average Precision (MAP) value is up to 76.5%. For GNOME, The recall at k=1 is around 63%, while this value increases by about 10% for k=2. The recall increases to 97% for k=11. A MAP value of up to 73% is achieved. Conclusion:We show that HMM and stack traces are a powerful combination for detecting and classifying duplicate bug reports in large bug repositories.

Abstract-Cooperative communication in wireless networkshas become more and more attractive recently since it could mitigate the particularly severe channel impairments arising from multipath propagation. Here the greater benefits gained by exploiting spatial diversity in the channel. In this paper, an overview on cooperative communication in wireless networks is presented. We inscribe the benefits of cooperative transmission than traditional non -cooperative communication. Practical issues and challenges in cooperative communication are identified. In particular, we present a study on the advantages, applications and different routing strategies for cooperative mesh networks, Ad hoc networks and wireless sensor networks.

No abstract

In directional wireless sensor networks (DSNs), sensor nodes with directional antennas provide extended network lifetime and better coverage performance. However, one of the key challenges of directional nodes is to discover their neighbors due to difficulty in achieving synchronization among their directed transmissions and receptions. Existing solutions suffer from high discovery latency and poor percentage of neighbor discovery either due to lack of proper coordination or centralized management of the discovery operation. In this work, we develop a collaborative neighbor discovery (COND) mechanism for DSNs. Each COND node polls to directly discover its neighbors in a distributed way and collaborates with the already discovered nodes so as to allow indirect discovery. It helps to increase the neighbor discovery performance significantly. A Markov chain-based analytical model is developed to quantify theoretical performances of the proposed COND system. The performance of the COND system is evaluated in Network Simulator Version 3, and simulation results reveal that it greatly reduces the discovery latency and increases neighbor discovery ratio compared to state-of-the-art approaches.