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West Bengal, India

Chakraborty M.,Asansol Girls College | Sen S.,Triveni Devi Bhalotia College
Journal of Electron Spectroscopy and Related Phenomena | Year: 2015

Abstract Quantum entanglement and its paradoxical properties are genuine physical resources for various quantum information tasks like quantum teleportation, quantum cryptography, and quantum computer technology. The physical characteristic of the entanglement of quantum-mechanical states, both for pure and mixed, has been recognized as a central resource in various aspects of quantum information processing. In this article, we study the bipartite entanglement of one electronic qubit along with the ionic qudit and also entanglement between two electronic qubits. The tripartite entanglement properties also have been investigated between two electronic qubits and an ionic qudit. All these studies have been done for the single-step double photoionization from an atom following the absorption of a single photon without observing spin orbit interaction. The dimension of the Hilbert space of the qudit depends upon the electronic state of the residual photoion A2+. In absence of SOI, when Russell-Saunders coupling (L-S coupling) is applicable, dimension of the qudit is equal to the spin multiplicity of A2+. For estimations of entanglement and mixedness, we consider the Peres-Horodecki condition, concurrence, entanglement of formation, negativity, linear and von Neumann entropies. In case of L-S coupling, all the properties of a qubit-qudit system can be predicted merely with the knowledge of the spins of the target atom and the residual photoion. © 2015 Elsevier B.V. Source


Mallick S.,Triveni Devi Bhalotia College | Bardhan S.,Jadavpur University | Das S.S.,Indian Statistical Institute | Paul S.,Indian Institute of Science | Goswami P.,Jadavpur University
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2014

One of the important and well documented prey-predator interactions in the fossil record is drilling predation done by naticid gastropods which diversified during the Cretaceous. Although drilling frequencies showed fluctuating patterns, most of the previous studies argued that naticid drilling predation was less intense during the Cretaceous and the modern values were achieved since the Paleocene.We, here, present a new dataset of naticid drilling predations, involving 31,929 gastropod specimens, from the latest Maastrichtian Infratrappean bed in Rajahmundry, southern India. These specimens belonged to 40 species of 20 families, thus representing a spectacular gastropod diversity that was not known until recently from this region. We examined 5884 complete or near complete specimens to quantify naticid drilling predation on this assemblage. It appeared that drilling frequency was significantly higher from all previous Cretaceous values. This was true for both assemblage-level and lower taxon-level results. Along with high successful drilling and low unsuccessful drilling frequencies, site and size stereotypy of drillholes suggest that naticid predators were highly efficient, even in the Cretaceous. Predators were prey selective and there was poor correlation between relative abundance and drilling frequency of prey taxa.The present Maastrichtian assemblage underlies the K-T mass extinction level. Drilling frequency was zero in the straddler prey community in the Intertrappean bed found immediately above the K-T boundary. The absence of any drillhole in surviving prey taxa may be due to sudden reduction in abundance of escalated predators, although some prey taxa e.g., cerithiids continued. This emphasizes the role of mass extinction in disrupting predator-prey interaction.We conclude that naticid drilling-induced escalation was already established during the Cretaceous and the present find extends the paleobiogeography of naticid predation (which was previously reported from the western world) up to India. © 2014 Elsevier B.V. Source


Mandal S.,Visva Bharati University | Mandal S.,Triveni Devi Bhalotia College | Ray S.,Visva Bharati University | Ghosh P.B.,Institute of Engineering and Management
Natural Resource Modeling | Year: 2012

Abstract Degradation of litter from mangrove forests adjacent to the creeks at Sagar Island of the Hooghly-Matla estuarine ecosystem is one of the principal sources of nutrient to the estuary. Nutrients augment the growth of phytoplankton, which in turn stimulates the production of zooplankton. Zooplankton serves as major food source for fish population of this estuarine system. Here, a dynamic model with three state variables (nutrient, phytoplankton, and zooplankton) is proposed using nitrogen (mgN/l) as currency. Input of dissolved inorganic nitrogen as nutrient, water temperature, surface solar irradiance, and salinity of upstream and downstream of the estuary, collected from the field, are incorporated as graph time functions in the model. Calibration and validation are performed by using collected data of two consecutive years. Model results indicate that the growth of zooplankton and phytoplankton are enhanced by increase in nutrient input in the system. Zooplankton biomass is affected by decrease in the salinity of the estuary. Sensitivity analysis results at ±10% indicate that maximum growth rate of phytoplankton (P max) is the most sensitive parameter to the nutrient pool although growth rate of zooplankton (g z) and half saturation constant for phytoplankton grazing by zooplankton (K z) are most sensitive parameters to phytoplankton and zooplankton compartments, respectively. The model depicts the present status of plankton dynamics, which serve as major food resource for herbivorous and carnivorous fish species of the estuary. Effect of deforestation is tested in the model. Therefore, from management perspective, this model can be used to predict the impact of mangroves on nutrient and plankton dynamics, which will give complete information of both shell and fin fish productions in the estuary. © 2012 Wiley Periodicals, Inc. Source


Mandal S.,Triveni Devi Bhalotia College | Mukhopadhyay S.K.,Hooghly Mohsin College | Ray S.,Visva Bharati University
Ecological Modelling | Year: 2015

The East Calcutta Wetlands is one of the largest wastewater-fed aquaculture in the world. It is the aggregation of salt marshes, salt meadows and wastewater-fed ponds that receive wastewater from various small and large scale industries and urban settlements. The available nutrient supports the grazing food chain of the wetland ecosystem and agriculture around it. Eutrophication is caused by the imbalance between nutrient load and utilization by the autotrophs in the system. In this wetland, there has been a gradual decrease in the fish production for the last few decades. The physical and chemical conditions of the system are deteriorating continuously. Therefore, modelling of the system is felt to be the need of the hour to mitigate the problem of eutrophication and identify the important parameters that govern the system dynamics.Here, a dynamic model is constructed to study the phosphorus dynamics of the system. The five state variable includes; inorganic phosphorus (orthophosphate), phytoplankton, zooplankton, organic phosphorus and sediment. Important processes, like mineralization, uptake, grazing, predation, settling, resuspension and sorption are considered in the model. Field data are collected over two years and incorporated in the model as graph time function. Sensitivity analysis is performed and the model is calibrated using first set data followed by the validation process. Results indicate that the wetland is in hypereutrophic condition. The model result shows that the inorganic phosphorus of the system is mainly controlled by desorption of phosphorus from the sediments and mineralization during the premonsoon. The settling of organic phosphorus and adsorption of inorganic phosphorus are major regulating processes in the postmonsoon. In monsoon, resuspension process has important role in governing the phosphorus dynamics of the wetland. Moreover, allochthonous input of phosphorus is dominant over autochthonus input and controls the system dynamics. The input rate of inorganic phosphorus from outside is the system sensitive parameter. The paper discusses the present condition of the East Calcutta Wetlands and outlines some of the important management strategies that can be applied to alleviate the eutrophication problem of the wetland ecosystem. © 2014 Elsevier B.V. Source


Samanta S.,CSIR - Central Electrochemical Research Institute | Ghoshal A.,CSIR - Central Electrochemical Research Institute | Ghoshal A.,Triveni Devi Bhalotia College | Bhattacharya K.,CSIR - Central Electrochemical Research Institute | And 2 more authors.
PLoS ONE | Year: 2012

Visceral leishmaniasis (VL) caused by the intracellular parasite Leishmania donovani accounts for an estimated 12 million cases of human infection. It is almost always associated with anemia, which severely complicates the disease course. However, the pathological processes leading to anemia in VL have thus far not been adequately characterized to date. In studying the glycosylation patterns of peripheral blood cells we found that the red blood cells (RBC) of VL patients (RBCVL) express eight 9-O-acetylated sialoglycoproteins (9-O-AcSGPs) that are not detected in the RBC of healthy individuals (RBCN). At the same time, the patients had high titers of anti-9-O-AcSGP IgG antibodies in their sera. These two conditions appear to be linked and related to the anemic state of the patients, as exposure of RBCVL but not RBCN to anti-9-O-AcSGPs antibodies purified from patient sera triggered a series of responses. These included calcium influx via the P/Q-type but not L-type channels, activation of calpain I, proteolysis of spectrin, enhanced oxidative stress, lipid peroxidation, externalization of phosphatidyl serine with enhanced erythrophagocytosis, enhanced membrane fragility and, finally, hemolysis. Taken together, this study suggests that the enhanced hemolysis is linked to an impairment of membrane integrity in RBCVL which is mediated by ligand-specific interaction of surface 9-O-AcSGPs. This affords a potential explanation for the structural and functional features of RBCVL which are involved in the hemolysis related to the anemia which develops in VL patients. © 2012 Samanta et al. Source

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