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Search Results: 1 - 10 of 311986 matches for " P. K. Sikdar "
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Understanding wetland sub-surface hydrology using geologic and isotopic signatures
P. K. Sikdar ,P. Sahu
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2009,
Abstract: This paper attempts to utilize hydrogeology and isotope composition of groundwater to understand the present hydrological processes prevalent in a freshwater wetland, source of wetland groundwater, surface water/groundwater interaction and mixing of groundwater of various depth zones in the aquifer. This study considers East Calcutta Wetlands (ECW) – a freshwater peri-urban inland wetland ecosystem located at the lower part of the deltaic alluvial plain of South Bengal Basin and east of Kolkata city. This wetland is well known over the world for its resource recovery systems, developed by local people through ages, using wastewater of the city. Geological investigations reveal that the sub-surface geology is completely blanketed by the Quaternary sediments comprising a succession of silty clay, sand of various grades and sand mixed with occasional gravels and thin intercalations of silty clay. At few places the top silty clay layer is absent due to scouring action of past channels. In these areas sand is present throughout the geological column and the areas are vulnerable to groundwater pollution. Groundwater mainly flows from east to west and is being over-extracted to the tune of 65×103 m3/day. δ18O and δD values of shallow and deep groundwater are similar indicating resemblance in hydrostratigraphy and climate of the recharge areas. Groundwater originates mainly from monsoonal rain with some evaporation prior to or during infiltration and partly from bottom of ponds, canals and infiltration of groundwater withdrawn for irrigation. Relatively high tritium content of the shallow groundwater indicates local recharge, while the deep groundwater with very low tritium is recharged mainly from distant areas. At places the deep aquifer has relatively high tritium, indicating mixing of groundwater of shallow and deep aquifers. Metals such as copper, lead, arsenic, cadmium, aluminium, nickel and chromium are also present in groundwater of various depths. Therefore, aquifers of wetland and surrounding urban areas which are heavily dependent on groundwater are vulnerable to pollution. In the area south of ECW isotope data indicates no interaction between shallow and deep aquifer and hence this area may be a better location to treat sewage water than within ECW. To reduce the threat of pollution in ECW's aquifer, surface water-groundwater interaction should be minimized by regulating tubewell operation time, introducing treated surface water supply system and artificial recharging of the aquifer.
Understanding wetland sub-surface hydrology using geologic and isotopic signatures
P. K. Sikdar,P. Sahu
Hydrology and Earth System Sciences Discussions , 2009,
Abstract: This paper attempts to utilize hydrogeoloy and isotope composition of groundwater to understand the present hydrological processes prevalent in a freshwater wetland, source of wetland groundwater, surface water/groundwater interaction and mixing of groundwater of various depth zones in the aquifer. This study considers East Calcutta Wetlands (ECW) – a freshwater peri-urban inland wetland ecosystem located at the lower part of the deltaic alluvial plain of South Bengal Basin and east of Kolkata city. This wetland is well known over the world for its resource recovery systems, developed by local people through ages, using wastewater from the city. Geological investigations reveal that the sub-surface geology is completely blanketed by the Quaternary sediments comprising a succession of silty clay, sand of various grades and sand mixed with occasional gravels and thin intercalations of silty clay. Aquifer within the depths of 80 m to 120 m has the maximum potential to supply water. Groundwater mainly flows from east to west and is being over-extracted to the tune of 65×103 m3/day. δ18O and δD values of shallow and deep groundwater are similar indicating resemblance in hydrostratigraphy and climate of the recharge areas. Groundwater originates mainly from monsoonal rain with some evaporation prior to or during infiltration and partly from bottom of ponds, canals and infiltration of groundwater withdrawn for irrigation. Relatively high tritium content of the shallow groundwater indicates local recharge, while the deeper groundwater with very low tritium is recharged mainly from distant areas. At places the deeper aquifer has relatively high tritium, indicating mixing of groundwater of shallow and deep aquifers. Metals such as copper, lead, arsenic, cadmium, aluminum, nickel and chromium are also present in groundwater of various depths. Therefore, aquifers of wetland and surrounding urban areas which are heavily dependent on groundwater are vulnerable to pollution and hence surface water-groundwater interaction should be minimized by regulating tubewell operation time, introducing treated surface water supply system and artificially recharging the aquifer.
ACE Gene Insertion/Deletion Polymorphism and Type-2 Diabetic Nephropathy in Eastern Indian Population
Mithun Sikdar,Pulakes Purkait,P. Raychoudhury,S. K. Bhattacharya
Human Biology Review , 2013,
Abstract: Background: Nephropathy is one of the major complications among the patients having type 1 or long term Type 2 diabetes and there are various studies that suggest its genetic predisposition. A 287 bp insertion/deletion (I/D) polymorphism of the gene encoding angiotensin-I converting enzyme (ACE) is shown to have association with diabetic nephropathy. Aim: To identify the association of ACE I/D polymorphism with subjects having diabetic nephropathy.Materials and methods: The present study examined the prevalence of ACE insertion/deletion polymorphism among 91 Bengali individuals from Eastern India. Among them 30 individuals belong to diabetic nephropathy (DN), 30 individuals having diabetes without nephropathy (DM) and 31 normal controls. The DNA samples of studied subjects were genotyped using polymerase chain reaction.Results: The frequency of DD, ID and II genotypes in patients having diabetic nephropathy (DN) were found to be 26.7%, 53.3% and 20.0% respectively, whereas the same for only diabetic patients (DM) were 26.7%, 50.0%and 23.3% respectively. The frequencies of the same genotypes among the normal controls were found to be 9.68%, 64.5% and 25.8% respectively. Inspite of a slightly higher odds ratio for DD genotypes among DM and DN subjects in comparison to the normal group the distribution pattern of DD genotype did not differ significantly within the three cohorts. The frequency of D allele among the patients having diabetic nephropathy, diabetic without nephropathy and control subjects was found to be 0.533, 0.516 and 0.420 respectively. This distribution pattern also did not differ significantly (χ2=1.859, p>0.05).Conclusion: No significant association was found between ACE I/D polymorphism with diabetic nephropathy patients from Bengali caste population.
Analysis and synthesis of nonlinear reversible cellular automata in linear time
Sukanta Das,Biplab K Sikdar
Physics , 2013,
Abstract: Cellular automata (CA) have been found as an attractive modeling tool for various applications, such as, pattern recognition, image processing, data compression, encryption, and specially for VLSI design & test. For such applications, mostly a special class of CA, called as linear/additive CA, have been utilized. Since linear/additive CA refer a limited number of candidate CA, while searching for solution to a problem, the best result may not be expected. The nonlinear CA can be a better alternative to linear/additive CA for achieving desired solutions in different applications. However, the nonlinear CA are yet to be characterized to fit the design for modeling an application. This work targets characterization of the nonlinear CA to utilize the huge search space of nonlinear CA while developing applications in VLSI domain. An analytical framework is developed to explore the properties of CA rules. The characterization is directed to deal with the reversibility, as the reversible CA are primarily targeted for VLSI applications. The reported characterization enables us to design two algorithms of linear time complexities -- one for identification and nother for synthesis of nonlinear reversible CA. Finally, the CA rules are classified into 6 classes for developing further efficient synthesis algorithm.
Energy and Water Sustainability: What do They Mean and Can We Know When We Achieved Them?
Subhas K. Sikdar,Daniel J. Murray
Environmental Research, Engineering and Management , 2010, DOI: 10.5755/j01.erem.52.2.66
Abstract: The word "sustainability" has been applied to resources such as energy and water, in addition to products, processes, urban infrastructure such as a city, or a quasi-natural infrastructure such as an eco-system. While there have been reasonable attempts made to evaluate the sustainability status of product and process systems from economic, environmental and societal impacts perspectives, no such systematic or rigorous analysis has been attempted for water and energy as resources, or water and energy supply systems. This discussion covers the essential sustainability concerns of water and energy systems and provides some thoughts on how one evaluates sustainability status and pathways for improvements.
Reversible Logic-Based Fault-Tolerant Nanocircuits in QCA
Bibhash Sen,Siddhant Ganeriwal,Biplab K. Sikdar
ISRN Electronics , 2013, DOI: 10.1155/2013/850267
Abstract: Parity-preserving reversible circuits are gaining importance for the development of fault-tolerant systems in nanotechnology. On the other hand, Quantum-dot Cellular Automata (QCA), a potential alternative to CMOS, promises efficient digital design at nanoscale. This work targets design of reversible ALU (arithmetic logic unit) in QCA (Quantum-dot Cellular Automata) framework. The design is based on the fault tolerant reversible adders (FTRA) introduced in this paper. The proposed fault tolerant adder is a parity-preserving gate, and QCA implementation of FTRA achieved 47.38% fault-free output in the presence of all possible single missing/additional cell defects. The proposed designs are verified and evaluated over the existing ALU designs and found to be more efficient in terms of design complexity and quantum cost. 1. Introduction Reversible logic has attractive perspective of constructing digital devices that can realize computing unit with almost zero power dissipation. Landauer [1] proved that for irreversible computations, each bit of information loss generates joules of heat energy. The energy required for a binary transition is given by SNL (Shannon-Von Neumann-Landauer) expression in [1] as follows: where is Boltzmann constant and ?K. This is the minimum energy to process a bit. Bennett [2] showed that a zero power dissipation in logic circuit is possible only if the circuit is composed of reversible logic gates. Since QCA circuits are clocked information preserving systems, the energy dissipation of QCA circuits can be significantly lower than . This feature favours the introduction of QCA technology in reversible logic design. Though, reversibility recovers bit loss, but it is not able to detect bit error in circuit. Fault-tolerant reversible circuits are capable of preventing errors at outputs. If the system itself made of fault-tolerant components, then the detection and correction of faults become easier and simple. In communication and many other systems, fault tolerance is achieved by parity. Therefore, parity-preserving reversible circuits will be the future design trends to the development of fault-tolerant reversible systems in nanotechnology. On the other hand, QCA (Quantum-dot Cellular Auto-mata) is considered to be promising in the field of nanotechnology due to their extremely small sizes and ultralow-power consumption [3]. The QCA is based on encoding binary information in the charge configuration of quantum-dot cells. The interaction between cells is coulombic and provides the necessary computing power. The fundamental unit of
Signature of nonexponential nuclear decay
A Ray,A K Sikdar,A De
Physics , 2015,
Abstract: Precision tests of decay law of radioactive nuclei have not so far found any deviation from the exponential decay law at early time, as predicted by quantum mechanics. In this paper, we show that the quantum decoherence time (i.e. the timescale of nonexponential decay) of the quasifission or fission process should be of the order of attosecond considering the atom of the fissioning nucleus as a quantum detector. Hence, the observed decay timescale of the quasifission or fission process of even highly excited (EX greater than 50 MeV) transuranium and uraniumlike complexes should be rather long (of the order of attosecond) in spite of their very fast exponential decay timescale (of the order of zeptosecond) as measured by the nuclear techniques. Recent controversy regarding the observation of very long (of the order of attosecond ) and very short (of the order of zeptosecond ) quasifission or fission timescales for similar systems at similar excitation energies as obtained by direct techniques (crystal blocking, X ray fission fragment) and nuclear techniques could be interpreted as evidence for nonexponential decays in nuclear systems
A Different Approach for Big Bang Singularity  [PDF]
Malay Kanti Sikdar
Natural Science (NS) , 2018, DOI: 10.4236/ns.2018.104016
Abstract: With the discovery of Hubble Red Shift in the cosmological Universe, the question of Big Bang explosion has become inevitable and to explain this point of singularity thereon. Dissolution and manifestation of the universe happen to occur periodically. In this paper,analysis has been undertaken on the basis of scientific development on well accepted cosmological model, different scientific concepts and on one Vedic/Tantric scriptural remark. According to Vedic/Tantric scriptural remark, at the time of dissolution of the universe it remains in the form of gram. Different scientific tools like Electron Microscopy, X-rays powder diffraction method. Raman & UV spectroscopy have been applied in analyzing the two parts of gram and finally to find out what do they correspond to cosmological analysis of Big Bang singularity. Main mechanisms in action in dissolution and manifestation have also been pointed out.
Implementation of a Purely Hardware-assisted VMM for x86 Architecture
Saidalavi Kalady,Dileep P. G,Krishanu Sikdar,Sreejith B. S
Lecture Notes in Engineering and Computer Science , 2009,
Abstract:
Nutritional status among the Mising tribal children of Northeast India with respect to their arm fat area and arm muscle area
Mithun Sikdar
Human Biology Review , 2012,
Abstract: The study highlights the nutritional status of two thousand nine hundred and sixty five (2965) numbers of Mising (a scheduled tribe) children of Upper Assam with the help of two derived nutritional indices i.e. Arm Fat Area (AFA) and Arm Muscle Area (AMA). The mean values and their descriptive statistics of AFA as well as AMA are presented for each group of children starting from 6 to 20 years of age. A sexual variation has been found in terms of the mean values of both the indices and is more marked in the early childhood and late adolescent period. With respect to the United States standard the Arm Fat Area indicates that Mising girls suffer relatively more than the Mising boys. On the other hand with respect to Arm Muscle Area Mising boys are found to be more sufferer than the girls. The Mising boys shows higher mean values for AMA than those of the girls whereas an opposite trend of sexual variation is found with respect to AFA. The results indicate that the boys tend to accumulate more muscle and girls more fat in their growth period. With the present study it can be said that to delineate the nutritional status of a particular community several parameters should be taken into consideration at a time to come to a final conclusion.
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