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Search Results: 1 - 10 of 1019 matches for " Biswa Sengupta "
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Action Potential Energy Efficiency Varies Among Neuron Types in Vertebrates and Invertebrates
Biswa Sengupta,Martin Stemmler,Simon B. Laughlin,Jeremy E. Niven
PLOS Computational Biology , 2010, DOI: 10.1371/journal.pcbi.1000840
Abstract: The initiation and propagation of action potentials (APs) places high demands on the energetic resources of neural tissue. Each AP forces ATP-driven ion pumps to work harder to restore the ionic concentration gradients, thus consuming more energy. Here, we ask whether the ionic currents underlying the AP can be predicted theoretically from the principle of minimum energy consumption. A long-held supposition that APs are energetically wasteful, based on theoretical analysis of the squid giant axon AP, has recently been overturned by studies that measured the currents contributing to the AP in several mammalian neurons. In the single compartment models studied here, AP energy consumption varies greatly among vertebrate and invertebrate neurons, with several mammalian neuron models using close to the capacitive minimum of energy needed. Strikingly, energy consumption can increase by more than ten-fold simply by changing the overlap of the Na+ and K+ currents during the AP without changing the APs shape. As a consequence, the height and width of the AP are poor predictors of energy consumption. In the Hodgkin–Huxley model of the squid axon, optimizing the kinetics or number of Na+ and K+ channels can whittle down the number of ATP molecules needed for each AP by a factor of four. In contrast to the squid AP, the temporal profile of the currents underlying APs of some mammalian neurons are nearly perfectly matched to the optimized properties of ionic conductances so as to minimize the ATP cost.
Balanced Excitatory and Inhibitory Synaptic Currents Promote Efficient Coding and Metabolic Efficiency
Biswa Sengupta ,Simon B. Laughlin,Jeremy E. Niven
PLOS Computational Biology , 2013, DOI: 10.1371/journal.pcbi.1003263
Abstract: A balance between excitatory and inhibitory synaptic currents is thought to be important for several aspects of information processing in cortical neurons in vivo, including gain control, bandwidth and receptive field structure. These factors will affect the firing rate of cortical neurons and their reliability, with consequences for their information coding and energy consumption. Yet how balanced synaptic currents contribute to the coding efficiency and energy efficiency of cortical neurons remains unclear. We used single compartment computational models with stochastic voltage-gated ion channels to determine whether synaptic regimes that produce balanced excitatory and inhibitory currents have specific advantages over other input regimes. Specifically, we compared models with only excitatory synaptic inputs to those with equal excitatory and inhibitory conductances, and stronger inhibitory than excitatory conductances (i.e. approximately balanced synaptic currents). Using these models, we show that balanced synaptic currents evoke fewer spikes per second than excitatory inputs alone or equal excitatory and inhibitory conductances. However, spikes evoked by balanced synaptic inputs are more informative (bits/spike), so that spike trains evoked by all three regimes have similar information rates (bits/s). Consequently, because spikes dominate the energy consumption of our computational models, approximately balanced synaptic currents are also more energy efficient than other synaptic regimes. Thus, by producing fewer, more informative spikes approximately balanced synaptic currents in cortical neurons can promote both coding efficiency and energy efficiency.
Information and Efficiency in the Nervous System—A Synthesis
Biswa Sengupta ,Martin B. Stemmler,Karl J. Friston
PLOS Computational Biology , 2013, DOI: 10.1371/journal.pcbi.1003157
Abstract: In systems biology, questions concerning the molecular and cellular makeup of an organism are of utmost importance, especially when trying to understand how unreliable components—like genetic circuits, biochemical cascades, and ion channels, among others—enable reliable and adaptive behaviour. The repertoire and speed of biological computations are limited by thermodynamic or metabolic constraints: an example can be found in neurons, where fluctuations in biophysical states limit the information they can encode—with almost 20–60% of the total energy allocated for the brain used for signalling purposes, either via action potentials or by synaptic transmission. Here, we consider the imperatives for neurons to optimise computational and metabolic efficiency, wherein benefits and costs trade-off against each other in the context of self-organised and adaptive behaviour. In particular, we try to link information theoretic (variational) and thermodynamic (Helmholtz) free-energy formulations of neuronal processing and show how they are related in a fundamental way through a complexity minimisation lemma.
Consequences of Converting Graded to Action Potentials upon Neural Information Coding and Energy Efficiency
Biswa Sengupta ,Simon Barry Laughlin,Jeremy Edward Niven
PLOS Computational Biology , 2014, DOI: doi/10.1371/journal.pcbi.1003439
Abstract: Information is encoded in neural circuits using both graded and action potentials, converting between them within single neurons and successive processing layers. This conversion is accompanied by information loss and a drop in energy efficiency. We investigate the biophysical causes of this loss of information and efficiency by comparing spiking neuron models, containing stochastic voltage-gated Na+ and K+ channels, with generator potential and graded potential models lacking voltage-gated Na+ channels. We identify three causes of information loss in the generator potential that are the by-product of action potential generation: (1) the voltage-gated Na+ channels necessary for action potential generation increase intrinsic noise and (2) introduce non-linearities, and (3) the finite duration of the action potential creates a ‘footprint’ in the generator potential that obscures incoming signals. These three processes reduce information rates by ~50% in generator potentials, to ~3 times that of spike trains. Both generator potentials and graded potentials consume almost an order of magnitude less energy per second than spike trains. Because of the lower information rates of generator potentials they are substantially less energy efficient than graded potentials. However, both are an order of magnitude more efficient than spike trains due to the higher energy costs and low information content of spikes, emphasizing that there is a two-fold cost of converting analogue to digital; information loss and cost inflation.
A New Institutional Architecture for Managing and Financing Pan-Asian Infrastructure Connectivity  [PDF]
Biswa Nath Bhattacharyay, Madhurima Bhattacharyay
Theoretical Economics Letters (TEL) , 2018, DOI: 10.4236/tel.2018.814178
Abstract: Asia, particularly its major economies has witnessed slower growth in recent years. To make Asia more economically sustainable and resilient against external shocks to recover from the falling growth, most regional economies need to rebalance their export-oriented (mostly to advanced economies) production and growth towards Asian markets and regional demand, and trade-driven growth through increased intraregional infrastructure connectivity and regional economic integration. In 1992, a pan-Asian transport connectivity was initiated through, Asian Highway Network and Trans-Asian Railways Network. In 2015, an ambitious pan-Asian connectivity initiative, namely “One Belt, One Road” (ancient silk road) initiative has been proposed. This initiative plans to create an economic zone covering Asia, Europe and Africa. To successfully promote and finance greater physical connectivity, at the pan-Asian, sub-regional and national levels, Asia will require a strong and appropriate institutional framework for effective coordination, cooperation and collaboration among national, subregional, and region-wide institutions as well as other stakeholders. This paper discusses the prospects and challenges facing Asian connectivity. It also examines huge infrastructure financing needs in Asia and ways and means to meet infrastructure financing gap in view of limited public finance. The paper proposes Multicurrency Infrastructure Bonds (MIBs) denominated in regional accounting units (RAUs) for financing regional infrastructure projects together with a comparison with the European Unit of Account (EUA) created in 1975. It also examines the nature and characteristics of existing and new institutions and the emerging role of regional and international institutions for enhancing Asian connectivity. Lastly, it proposes an institutional architecture consisting of new “Asian Infrastructure Coordination Facility (AICF)” involving major stakeholders for building a seamless pan-Asian connectivity through bilateral, regional and international cooperation, partnership and collaboration in infrastructure development.
Challenges to rational prescribing and use of essential medicines in India
Biswa Mohan Padhy
International Journal of Basic & Clinical Pharmacology , 2013, DOI: 10.5455/2319-2003.ijbcp20130101
Abstract: The concept of essential medicines was introduced in 1977 with the publication of the World Health Organization's (WHO) Model List of Essential Medicines. These medicines are intended to satisfy the priority health care needs of the population. They are selected with regard to public health relevance, evidence of efficacy and safety, and comparative cost-effectiveness. Essential medicines are intended to be available within the context of functioning health systems at all times in adequate amounts, in the appropriate dosage forms, with assured quality and at a price the individual and the community can afford. The WHO advises countries to adapt the essential medicines list according to their priority health care needs. The model list of WHO serves as a guide for the development of a national list of essential medicines (NLEM). An essential medicines list can serve as a model for procurement, local licensing and manufacturing, and the rational use of good-quality medicines, especially within the public sector. It also helps in allocating limited resources effectively and in a cost-effective manner. [Int J Basic Clin Pharmacol 2013; 2(1.000): 1-3]
International Journal of Engineering Science and Technology , 2011,
Abstract: Wireless sensor networks consist of small battery powered sensor nodes with limited energy resources. The area of wireless sensor networks is now attractive in the research area due to its applications in many fields such as defense security, civilian applications and medical research etc. In wireless sensor networks, the important task is to periodically collect data from an area of interest for time-sensitive applications. Then the sensed data must be gathered and transmitted to a base station for further processing to meet the end-user queries. Routing is a serious issue in WSN due to the use of computationally-constrained and resourceconstrainedmicro-sensors. Once the sensor nodes are deployed replacement is not feasible. Hence, energy efficiency is a key design issue to improve the life span of the network. Since the network consists of low-costnodes with limited battery power, it is a challenging task to design an efficient routing scheme that can offer good performance in energy efficiency, and long network lifetimes.
Biswa Nath Das*,Nazmul Qais
Pharmacie Globale : International Journal of Comprehensive Pharmacy , 2012,
Abstract: The investigation was conducted with crude methanolic extract of rhizome of Alpinia nigra for its antibacterial cytotoxic and activities. Antibacterial activity of the extract was evaluated against various Gram-positive and Gram-negative bacteria using disk diffusion technique. For cytotoxic activity, brine shrimp lethality bioassay was performed to estimate LC50 values. In our preliminary screening, the n-hexane, carbon tetrachloride, and dichloromethane soluble fractions of the crude methanolic extract of Alpinia nigra were subjected to antibacterial activity and brine shrimp lethality bioassay. The carbon tetrachloride soluble partitionate of the methanol extract exhibited mild to moderate antibacterial activity and strong cytotoxicity having LC50 of 0.832 μg/mL.
Application of Graph Entropy in CRISPR and Repeats Detection in DNA Sequences  [PDF]
Dipendra C. Sengupta, Jharna D. Sengupta
Computational Molecular Bioscience (CMB) , 2016, DOI: 10.4236/cmb.2016.63004
Abstract: We analyzed DNA sequences using a new measure of entropy. The general aim was to analyze DNA sequences and find interesting sections of a genome using a new formulation of Shannon like entropy. We developed this new measure of entropy for any non-trivial graph or, more broadly, for any square matrix whose non-zero elements represent probabilistic weights assigned to connections or transitions between pairs of vertices. The new measure is called the graph entropy and it quantifies the aggregate indeterminacy effected by the variety of unique walks that exist between each pair of vertices. The new tool is shown to be uniquely capable of revealing CRISPR regions in bacterial genomes and to identify Tandem repeats and Direct repeats of genome. We have done experiment on 26 species and found many tandem repeats and direct repeats (CRISPR for bacteria or archaea). There are several existing separate CRISPR or Tandem finder tools but our entropy can find both of these features if present in genome.
A New Approach to Software Development Fusion Process Model  [PDF]
Rupinder Kaur, Jyotsna Sengupta
Journal of Software Engineering and Applications (JSEA) , 2010, DOI: 10.4236/jsea.2010.310117
Abstract: There are several software process models that have been proposed and are based on task involved in developing and maintaining software product. The large number of software projects not meeting their expectation in terms of functionality, cost, delivery schedule and effective project management appears to be lacking. In this paper, we present a new software fusion process model, which depicts the essential phases of a software project from initiate stage until the product is retired. Fusion is component based software process model, where each component implements a problem solving model. This approach reduces the risk associated with cost and time, as these risks will be limited to a component only and ensure the overall quality of software system by considering the changing requirements of customer, risk assessment, identification, evaluation and composition of relative concerns at each phase of development process.
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