55 research outputs found

    Erythrocyte stability under imposed fields

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    Lysis of erythrocytes offers an unique opportunity to probe the fine structure of the bilayer as a function of its state of energization. Critical monitoring of the volumes, ion fluxes and related measures in erythrocytes exposed to a variety of milieu and treatments showed that one can critically distinguish the nature of the prelytic perturbations and the proximate forces actually responsible for the disruption of the membranes among surface charge density, elastic energy etc

    Effect of shape anisotropy on transport in a 2-dimensional computational model: Numerical simulations showing experimental features observed in biomembranes

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    We propose a 2-d computational model-system comprising a mixture of spheres and the objects of some other shapes, interacting via the Lennard-Jones potential. We propose a reliable and efficient numerical algorithm to obtain void statistics. The void distribution, in turn, determines the selective permeability across the system and bears a remarkable similarity with features reported in certain biological experiments.Comment: 1 tex file, 2 sty files and 5 figures. To appear in Proc. of StatPhys conference held in Calcutta, Physica A 199

    Definition of physical integrity of synaptosomes and myelosomes by enzyme osmometry

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    Isotonic requirements for synaptosomes were shown to vary with the concentration of sucrose or mannitol in the isolation medium, as well as with their differential permeability to polyols and ions. The technique of enzyme osmometry, which permits quantitation of the osmotic integrity in a heterogeneous population, was used to defined the osmotic requirements for synaptosomes and myelosomes in a variety of ionic and non-electrolyte media. Important differences, observed in the rank order of permeability of synaptosomal and myelosomal membranes to electrolyte media, were consistent with the known channel density/electrical activity of the corresponding plasma membranes

    Assessment of molecular sieving across bacterial outer membrane of Pseudomonas

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    AbstractThe role of the permeability barrier of the outer membrane of Pseudomonas was re-evaluated based on the physical theory of molecular sieving in view of its intrinsic antibiotic resistance. We veveloped a set of analytical procedures based on parametric and non-parametric statistical tests to evaluate, validate and adopt the better among a set of competing non-linear movels of diffusion. The molecular mass vepenvence of uptake of non-electrolytes in bacteria yielved a quantitative measure to distinguish between sieving mechanisms and specific uptake/efflux mechanisms. The experimental data, supported by the physical movel of veAE-Sephavex and various analytical movels and extensive simulation of the errors, both in measurement and movels, yielved evivence consistent with the relaxation of the outer membrane matrix barrier in Pseudomonas

    Needle in the Haystack: the art of scientific packaging

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    Ubiquinone-8 Stimulates Phagocytosis in Macrophages by Modulation of the Kinetics of the Fc Receptor

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    The effect of exogenous ubiquinone-8 (Q8) on IgG- and C3b-mediated phagocytosis of sensitized sheep red blood cells and of opsonized Staphylococcus aureus by macrophages was studied by morphological and quantitative methods. Q8 stimulated the initial events of phagocytosis, that is, attachment and ingestion, in which occupancy of the Fe receptor by IgG was shown to be of critical significance. The kinetics of competitive inhibition of phagocytosis of opsonized bacteria by macrophages by using Fe fragments suggested the intimate role of the kinetics of the Fe receptor in the initial events of phagocytosis and, further, the modulation of the kinetics of the Fe receptor by Q8 as the basis of enhanced phagocytosis by Q

    Ecology of ficus religiosa accounts for its association with religion

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    While many plants and trees in specific areas acquire cult significance, very few such as Ficus religiosa L. have acquired a universal status. This hemiepiphyte, Ficus religiosa L., is of dual interest since it venerated by a quarter of the present mankind (Hindus and Buddhists, largely Asian) on one hand and also since these plants are blamed for destruction of buildings due to their ability to grow on buildings. Divergence in views exists whether epiphytic plants exert a destructive influence on buildings. A focused survey of the coastal forts on land and sea has shown uniformly that the naturally growing plants of certain Ficus sp., notably Ficus religiosa L., grow exclusively on the vertical sheer side of rock faces and not either on the ground or on the top surface of these 8-10 centuries old rock structures; also seen on the side of rock piles as recent as 4-5 years as well as in sacred groves of several centuries to millennia old. We could trace the roots through these structures from beginning to the end in many parts of these forts, especially when there are overhanging structures at entrances. The root tips, the point of growth, would be far too insignificant to account for destruction in any of these large rock-and-lime masonry structures while vibration per se was insignificant as the tree was seen in all forts on land or sea. The association with religion of the distinctive Ficus religiosa itself appears to be self-evident from its socio-anthropological association with rock piles, hitherto not visualized for any flora and logically appears to pre-date both Hinduism and Buddhism

    Poverty index with time-varying consumption and income distributions

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    Starting from a stochastic agent-based model to represent market exchange in a developing economy, we study time variations of the probability density function of income with simultaneous variation of the consumption deprivation (CD), where CD represents the shortfall in consumption from the saturation level of an essential commodity, cereal. Together, these two models combine income-expenditure-based market dynamics with time variations in consumption due to income. In this new unified theoretical structure, exchange of trade in assets is only allowed when the income exceeds consumption-deprivation while CD itself is endogenously obtained from a separate kinetic model. Our results reveal that the nature of time variation of the CD function leads to a downward trend in the threshold level of consumption of basic necessities, suggesting a possible dietary transition in terms of lower saturation level of food-grain consumption, possibly through an improvement in the level of living. The new poverty index, defined as CD, is amenable to approximate probabilistic prediction within a short time horizon. A major achievement of this work is the intrinsic independence of the poverty index from an exogenous poverty line, making it more objective for policy formulation as opposed to existing poverty indices in the literature

    A social engineering model for poverty alleviation

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    Poverty, the quintessential denominator of a developing nation, has been traditionally defined against an arbitrary poverty line; individuals (or countries) below this line are deemed poor and those above it, not so! This has two pitfalls. First, absolute reliance on a single poverty line, based on basic food consumption, and not on total consumption distribution, is only a partial poverty index at best. Second, a single expense descriptor is an exogenous quantity that does not evolve from income-expenditure statistics. Using extensive income-expenditure statistics from India, here we show how a self-consistent endogenous poverty line can be derived from an agent-based stochastic model of market exchange, combining all expenditure modes (basic food, other food and non-food), whose parameters are probabilistically estimated using advanced Machine Learning tools. Our mathematical study establishes a consumption based poverty measure that combines labor, commodity, and asset market outcomes, delivering an excellent tool for economic policy formulation
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