Ultrasensitivity and Fluctuations in the Barkai-Leibler Model of Chemotaxis Receptors in {\it Escherichia coli}

A stochastic version of the Barkai-Leibler model of chemotaxis receptors in {\it E. coli} is studied here to elucidate the effects of intrinsic network noise in their conformational dynamics. It was originally proposed to explain the robust and near-perfect adaptation of {\it E. coli} observed across a wide range of spatially uniform attractant/repellent (ligand) concentrations. A receptor is either active or inactive and can stochastically switch between the two states. Enzyme CheR methylates inactive receptors while CheB demethylates active ones and the probability for it to be active depends on its level of methylation and ligandation. A simple version of the model with two methylation sites per receptor (M=2) shows zero-order ultrasensitivity (ZOU) akin to the classical 2-state model of covalent modification studied by Goldbeter and Koshland (GK). For extremely small and large ligand concentrations, the system reduces to two 2-state GK modules. A quantitative measure of the spontaneous fluctuations in activity (variance) estimated mathematically under linear noise approximation (LNA) is found to peak near the ZOU transition. The variance is a weak, non-monotonic and decreasing functions of ligand and receptor concentrations. Gillespie simulations for M=2 show excellent agreement with analytical results obtained under LNA. Numerical results for M=2, 3 and 4 show ZOU in mean activity; the variance is found to be smaller for larger M. The magnitude of receptor noise deduced from available experimental data is consistent with our predictions. A simple analysis of the downstream signaling pathway shows that this noise is large enough to have a beneficial effect on the motility of the organism. The response of mean receptor activity to small time-dependent changes in the external ligand concentration, computed within linear response theory, is found to have a bilobe form.Comment: Accepted in PLoS On

Financial intermediation and employment

This paper explores the relationship between financial intermediation and employment. We explain why some economies have low financial intermediation even when financial intermediation is safe. Moreover, we seek to explain why these economies tend to be poor and vulnerable, and also have large self-employment even when the latter has low productivity. We model safe but unsound banks and show that the effects of bad banking can be overcome only partially by corrective taxes. The model is extended to incorporate the illegal sector of the economy as well as the labor laws.Financial intermediation, self-employment, tax, labor laws

Artificial Intelligence in Material Engineering: A review on applications of AI in Material Engineering

Recently, there has been extensive use of artificial Intelligence (AI) in the field of material engineering. This can be attributed to the development of high performance computing and thereby feasibility to test deep learning models with large parameters. In this article we tried to review some of the latest developments in the applications of AI in material engineering.Comment: V

Synthesis of Graphene-Based Nanocomposite and Investigations of Its Thermal and Electrical Properties

We describe the synthesis of acid functionalized graphene (GE) which is grafted to chitosan (CH) by first reacting the oxidized GE with thionyl chloride to form acyl-chlorinated GE. This product is subsequently dispersed in chitosan and covalently grafted to form GE-chitosan. GE-chitosan is further grafted onto polymetanitroaniline (PMNA) by free radical polymerization conditions to yield GE-CH-PMNA. We have characterized the structure of synthesized GE-CH-PMNA composites by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy, and conductivity measurements. XRD data suggest the strongly crystalline character of the prepared specimen. Our measurement shows that the dielectric constants of these nanocomposites are remarkably enhanced due to interfacial polarization effect. This study demonstrates that functionalized graphene sheets are ideal nanofillers for the development of new polymer composites with high dielectric constant values

Unusual coexistence between lupus nephritis and neurofibromatosis 1: a case report and review of previous cases

The association of Neurofibromatosis 1 (NF 1), an autosomal dominant genetic disease with autoimmune diseases like systemic lupus erythematosus is rare, five case reports are there in medical literature showing such association. Here we have documented a case of Lupus nephritis associated with Neurofibromatosis 1 diagnosed in the same setting, in a 24 years old female patient presented with oliguria, hypertension, anasarca, cafe-au-lait spots, palmer freckling, subcutaneous nodules, alopecia areata and positive family history for NF 1

A statistical method for determining optical and geometrical characteristics of cirrus clouds

Altitude occurrences of cirrus clouds, their base, mid, and top heights are identified by using a powerful statistical approach called the Variance Centroid Method (VCM). This method is effective in determining the geometrical properties of cirrus clouds at a height range of 8 km to 20 km. This statistical method provides in-depth information on Generation Circulation Models (GCM’s) because of its significant role in the radiative balance of the earth’s atmosphere. The output related to geometrical and optical properties of cirrus clouds obtained from this statistical method for the years 2014 and 2015 are studied. Altitude distributions of base, mid, top, and thickness of tropical cirrus clouds are analyzed in terms of percentage occurrences. For the year 2014, it was found that 14.8%, 75.2%, and 9.9% of cirrus clouds were sub-visual, thin, and thick clouds and for the year 2015, 71.2% and 28.7% of cirrus clouds were found to be thin and thick clouds, and sub-visual types of clouds were not observed. The interdependence of optical depth with the depolarization ratio is discussed and it is observed that the correlation is negative (−0.0303) for the year 2014 and positive (0.1311) for the year 2015. High optical depths with values from 0.502 to 0.849 are observed in the height regions from 9 km to 15 km (for 2014) and for the year 2015, the observed value ranges from 0.514 to 0.822 for the height regions from 9 km to 11 km. Statistical variation of characteristics of tropical cirrus clouds is presented for the period of study. The characterization of these cirrus clouds is highly useful for climate modeling studies, and their impact plays a vital role in the Earth’s radiation budget at the top of the atmosphere

Two unusual neuro-psychiatric manifestations of malaria in a tertiary care hospital: a review of literature

Malaria, a highly prevalent parasitic disease in tropical country, have some atypical neuro-psychiatric manifestations seen in both vivax and falciparum malaria. We are reporting two cases of unusual neuro-psychiatric manifestations of malaria admitted in our hospital, one with intralobar haemorrhage and other with atypical psychiatric features. The rarity of the presentation has been highlighted with possible pathogenesis discussed after literature review