Bacterial Flora of Manasbal Lake, a Freshwater Ecosystem of Kashmir Valley

Micro-organisms have been used for a long time as indicators of water quality and total coliform bacteria have been commonly used to assess potential contamination of drinking and swimming water with pathogenic bacteria of intestinal origin coming from point source discharges, such as raw sewage, storm water, combined sewer overflows, effluents from wastewater treatment plants, industrial sources and non-point source discharge s, such as agriculture, forestry, wildlife, and urban run-off. The obtained data in this study reflect the importance of microbiological monitoring and reinf orce the need to implement environment protection programs, especially related to pathogenic species. The majority of bacteria isolated were recognized as human pathogens or potential human pathogens. The data was obtained by the bacteriological analysis of water sample taken from Manasbal Lake on monthly basis from four different microhabitats by plating the different dilutions on a solidified culture medium in petri dishes. After incubation the bacterial colonies were divided into different types according to some macromorphological features like appearance, shape, size, elevation, margin, colour and some micromorphological features with the isolated strains showing marked differences in these features. On the basis of these differences they were coded with numbers ranging from MBS01 to MBS52. The different recognizable colonies were streaked and restreaked on fresh media to obtain pure cultures. The selected purified colonies of various types were identified to genus or species level using biochemical tests. Total coliforms were enumerated using multiple tube fermentation technique with lactose broth as the presumptive medium and Eosine-Methylene-Blue agar medium as the confirmatory medium and Brilliant Green Bile broth for completed test. The developed colonies on plates were enumerated by digital Qubek colony counter and the bacterial load was assessed in terms of colony forming units (cfu/ml) revealing that the total monthly bacterial population increased from March to August and then decreased from September to December with peak bacterial population in the month of August at all sites. Moreover, the density of total culturable bacteria at site II (residential hamlets around) was significantly higher in all the months compared to other sites. The overall bacterial density was maximum at site II with a cfu/ml of 203x102 in the month of August and minimum at site III (central site) with a cfu/ml of 12x102 in the month of April. The total bacterial population was higher during warm temperature months than cold temperature months for all the four sites. As far as coliform count is concerned, all the water samples collected f rom the Lake were positive with respect to the coliform occurrence, with their proportion ranging between a minimum value of 4 MPN/100ml and a maximum value of 460 MPN/100ml. The highest proportion of these indicator organis ms was observed at site II. The category wise distribution of coliform count shows that about 95% samples lie in category II and III deeming the water unfit for drinking purposes, however, fit for bathing and swimming purposes. Moreover, the quality of water in some patches of the lake was very poor and unfit for any use. The water of the lake was characterised by a medium to high alkaline pH (ranging between 7.7 to 9.6) and temperature ranging between 9°C to 33.5°C. The overall Shannon diversity index (H) was highest at site I (Laar Kul) followed by site II, site III and site IV (outlet). The bacterial isolates were then tested for Gram’s reaction and subsequentl y examined under microscope for their cell shape revealing that 88.5% of the bacterial strains were Gram negative and 11.5% were Gram positive, out of which 34 strains (59.6%) were Gram negative bacillus, 12 strains (2 8.8%) were Gram negative cocci, 4 strains (7.6%) were Gram positive bacillus and 2 strains (3.8%) were Gram positive cocci. Among Gram-negative bacteria, b acillus was the most dominant genus isolated from all sites during all mo nths. A total of 19 bacterial strains, chosen arbitrarily were subjected to biochem ical tests like Citrate utilization, Glucose, Adonitol, Arabinose, Lactose, Sorbitol, Mannitol, Rhamnose, Sucrose, Urease, Lysine utilization, Ornithine ut ilization, H2S production, Phenylalanine Deamination, Nitrate utilization, Indole, Voges Proskauer’s and Methyl red revealed that 9 species viz Proteus spp. I, Proteus spp. II, Proteus spp. III, Escherichia coli, Klebsiella spp. II, Cedecea spp., Escherichia spp., Shigella spp. and Salmonella spp. belonged to Enterobacteriaceae family and 10 species viz Shigella spp. I, Shigella spp. II, Shigella spp. III, Enterobacter spp., Hafinia spp., Salmonella chloraesuis subspecies choleraesuis, Salmonella choleraesuis subspecies diarizonae, Vibrio sp p., Proteus spp. IV, and Klebsiella spp. I. to Gram negative rods. During the study Proteus spp. II occurred with a highest percentage occurrence of 14.67% and Shigella spp. I with a lowest percentage occurrence of 0.21%. Overall, the study allows us to conclude that the quality of lake water has deteriorated to the extent of being unfit for drinking purposes, though it is still fit for recreational and other uses. Hence, the lake calls for urgent restoration and eff ective management for its sustained existence and continued provisioning of various economic goods and ecosystem services

Realization of Integrable Low- Voltage Companding Filters for Portable System Applications

Undoubtedly, today’s integrated electronic systems owe their remarkable performance primarily to the rapid advancements of digital technology since 1970s. The various important advantages of digital circuits are: its abstraction from the physical details of the actual circuit implementation, its comparative insensitiveness to variations in the manufacturing process, and the operating conditions besides allowing functional complexity that would not be possible using analog technology. As a result, digital circuits usually offer a more robust behaviour than their analog counterparts, though often with area, power and speed drawbacks. Due to these and other benefits, analog functionality has increasingly been replaced by digital implementations. In spite of the advantages discussed above, analog components are far from obsolete and continue to be key components of modern electronic systems. There is a definite trend toward persistent and ubiquitous use of analog electronic circuits in day-to-day life. Portable electronic gadgets, wireless communications and the widespread application of RF tags are just a few examples of contemporary developments. While all of these electronic systems are based on digital circuitry, they heavily rely on analog components as interfaces to the real world. In fact, many modern designs combine powerful digital systems and complementary analog components on a single chip for cost and reliability reasons. Unfortunately, the design of such systems-on-chip (SOC) suffers from the vastly different design styles of analog and digital components. While mature synthesis tools are readily available for digital designs, there is hardly any such support for analog designers apart from wellestablished PSPICE-like circuit simulators. Consequently, though the analog part usually occupies only a small fraction of the entire die area of an SOC, but its design often constitutes a major bottleneck within the entire development process. Integrated continuous-time active filters are the class of continuous-time or analog circuits which are used in various applications like channel selection in radios, anti-aliasing before sampling, and hearing aids etc. One of the figures of merit of a filter is the dynamic range; this is the ratio of the largest to the smallest signal that can be applied at the input of the filter while maintaining certain specified performance. The dynamic range required in the filter varies with the application and is decided by the variation in strength of the desired signal as well as that of unwanted signals that are to be rejected by the filter. It is well known that the power dissipation and the capacitor area of an integrated active filter increases in proportion to its dynamic range. This situation is incompatible with the needs of integrated systems, especially battery operated ones. In addition to this fundamental dependence of power dissipation on dynamic range, the design of integrated active filters is further complicated by the reduction of supply voltage of integrated circuits imposed by the scaling down of technologies to attain twin objective of higher speed and lower power consumption in digital circuits. The reduction in power consumption with decreasing supply voltage does not apply to analog circuits. In fact, considerable innovation is required with a reduced supply voltage even to avoid increasing power consumption for a given signal to noise ratio (S/N). These aspects pose a great hurdle to the active filter designer. A technique which has attracted the attention of circuit designers as a possible route to filters with higher dynamic range per unit power consumption is “companding”. Companding (compression-expansion) filters are a very promising subclass of continuous-time analog filters, where the input (linear) signal is initially compressed before it will be handled by the core (non-linear) system. In order to preserve the linear operation of the whole system, the non-linear signal produced by the core system is converted back to a linear output signal by employing an appropriate output stage. The required compression and expansion operations are performed by employing bipolar transistors in active region or MOS transistors in weak inversion; the systems thus derived are known as logarithmic-domain (logdomain) systems. In case MOS transistors operated in saturation region are employed, the derived structures are known as Square-root domain systems. Finally, the third class of companding filters can also be obtained by employing bipolar transistors in active region or MOS transistors in weak inversion; the derived systems are known as Sinh-domain systems. During the last several years, a significant research effort has been already carried out in the area of companding circuits. This is due to the fact that their main advantages are the capability for operation in low-voltage environment and large dynamic range originated from their companding nature, electronic tunability of the frequency characteristics, absence of resistors and the potential for operations in varied frequency regions.Thus, it is obvious that companding filters can be employed for implementing high-performance analog signal processing in diverse frequency ranges. For example, companding filters could be used for realizing subsystems in: xDSL modems, disk drive read channels, biomedical electronics, Bluetooth/ZigBee applications, phaselocked loops, FM stereo demodulator, touch-tone telephone tone decoder and crossover network used in a three-way high-fidelity loudspeaker etc. A number of design methods for companding filters and their building blocks have been introduced in the literature. Most of the proposed filter structures operate either above 1.5V or under symmetrical (1.5V) power supplies. According to data that provides information about the near future of semiconductor technology, International Technology Roadmap for Semiconductors (ITRS), in 2013, the supply voltage of digital circuits in 32 nm technology will be 0.5 V. Therefore, the trend for the implementation of analog integrated circuits is the usage of low-voltage building blocks that use a single 0.5-1.5V power supply. Therefore, the present investigation was primarily concerned with the study and design of low voltage and low power Companding filters. The work includes the study about: the building blocks required in implementing low voltage and low power Companding filters; the techniques used to realize low voltage and low power Companding filters and their various areas of application. Various novel low voltage and low power Companding filter designs have been developed and studied for their characteristics to be applied in a particular portable area of application. The developed designs include the N-th order universal Companding filter designs, which have been reported first time in the open literature. Further, an endeavor has been made to design Companding filters with orthogonal tuning of performance parameters so that the designs can be simultaneously used for various features. The salient features of each of the developed circuit are described. Electronic tunability is one of the major features of all of the designs. Use of grounded capacitors and resistorless designs in all the cases makes the designs suitable for IC technology. All the designs operate in a low-voltage and low-power environment essential for portable system applications. Unless specified otherwise, all the investigations on these designs are based on the PSPICE simulations using model parameters of the NR100N bipolar transistors and BSIM 0.35μm/TSMC 0.25μm /TSMC 0.18μm CMOS process MOS transistors. The performance of each circuit has been validated by comparing the characteristics obtained using simulation with the results present in the open literature. The proposed designs could not be realized in silicon due to non-availability of foundry facility at the place of study. An effort has already been started to realize some of the designs in silicon and check their applicability in practical circuits. At the basic level, one of the proposed Companding filter designs was implemented using the commercially available transistor array ICs (LM3046N) and was found to verify the theoretical predictions obtained from the simulation results