Background: There has been increasing awareness throughout the world regarding the remarkable decrease in amphibian population. For such amphibian population decline several causes have been given. Cadmium, a heavy metal is released both from natural sources (leaching of cadmium rich soils) and anthropogenic activities to the aquatic and terrestrial environments. This study evaluated the toxicity of heavy metal cadmium to Indian skipper frog Rana cyanophlyctis. Methods: For the determination of LC50 values for cadmium, four-day static renewal acute toxicity test was used. Five replicates each containing ten frogs were subjected to each concentration of cadmium chloride (15, 20, 25, 30, 35, 40, 45 and 50 mg/L). At different exposure periods (24, 48, 72 and 96 h), the mortality of the frog was subjected to Probit analysis with the POLO-PC software (LeOra Software) to calculate the LC50 and 95% confidence level. Results: The LC50 values of cadmium chloride for the frog R. cyanophlyctis at 24, 48, 72, and 96 h are 32.586, 29.994, 27.219 and 23.048 mg/L, respectively. The results have been discussed with the toxicity reported for other aquatic vertebrate --fish. Conclusion: Cadmium caused mortality to the frog and this could be one of the reasons for population decline of frogs which inhabit water contaminated with heavy metals.

In this paper we check the performance of a GSM cellular communication system by using FDMA –TDMA system . In the present paper we evaluate the performance of the blocking probability, spectral efficiency and the bit error rate by using the a specific model. By using this we try to improve Rician and lognormal. Keywords— GSM, Multipath effect, TDMA, North-American system.

: The primary problem in today’s cellular network is to raise bandwidth efficiency of cellular system and handle blocking in the call between the subscribers. This will be done by improving the performance of system and reducing the interference to allow the users to achieve higher data rate. This designed system shows how to increase bandwidth efficiency and enhancement blocking probability in cellular system by using techniques of Dynamic Frequency Hopping where data transmission of the wireless regional area network system are performed in parallel with spectrum sensing without any interruption. This leads to an enhancement in performance of system and diminish the interference allowing the users to attain higher data rate. Keywords— Congestion control techniques, Outage probability, Propagation model, Bandwidth efficiency, Cellular system