Theory of the Three Dimensional Quantum Hall Effect in Graphite

We predict the existence of a three dimensional quantum Hall effect plateau in a graphite crystal subject to a magnetic field. The plateau has a Hall conductivity quantized at $\frac{4e^2}{\hbar} \frac{1}{c_0}$ with $c_0$ the c-axis lattice constant. We analyze the three-dimensional Hofstadter problem of a realistic tight-binding Hamiltonian for graphite, find the gaps in the spectrum, and estimate the critical value of the magnetic field above which the Hall plateau appears. When the Fermi level is in the bulk Landau gap, Hall transport occurs through the appearance of chiral surface states. We estimate the magnetic field necessary for the appearance of the three dimensional quantum Hall Effect to be $15.4$T for electron carriers and $7.0$T for hole carriers.Comment: Several new references adde

Effect of haemoglobin on the growth of mycobacteria and production of siderophores

Hemoglobin is known to support the growth of several bacterial species. The growth and the production of siderophores by 4 strains of mycobacteria in the presence of hemoglobin was studied in vitro. The findings were compared with those obtained in the presence of equivalent concentrations of iron in the medium. Increase in the concentrations of hemoglobin caused an appreciable increase in the growth of all 4 strains. This was however, accompanied by a significant decrease in the production of both exochelins and mycobactins. It was also observed that hemoglobin supported the growth of all strains as well as that with free iron and the concentrations of both siderophores was significantly higher in the presence of hemoglobin than in that of free iron

Siderophore-mediated iron uptake in mycobacteria

Iron is vital for the survival and proliferation of microorganisms, while mycobacteria also require this element for their survival within the host. To meet the demand for iron, mycobacteria synthesise and utilise specific high-affinity iron-binding compounds (siderophores) which help them grow in the’ iron-restricted conditions of the host [1, 2] and also participate in the uptake of iron across the thick lipid cell wall [3]. Two types of siderophores are produced by mycobacteria [3]. Exochelin occurs extracellularly to act as a scavenger, and mycobactin occurs on the cell wall to act as a transporter. Specific membrane proteins are also produced by several mycobacteria for the transport of siderophore-ferric iron complexes [4]. Recent work [5] demonstrated that the growth of Mycobacterium tuberculosis strains was increased with increasing concentrations of iron in the medium and that the concentrations of exochelins and mycobactins, which are highest under iron-deficient conditions, registered marked decreases. It does not follow, however, that exochelins are involved in the uptake of iron by mycobacteria. We have therefore studied the uptake of iron by four strains of mycobacteria in the absence and in the presence of exochelins released by these strains

Effect of iron on the growth and siderophore production of mycobacteria

To gain a better understanding of the role of iron in the pathogenesis of tuberculosis, the growth and production of siderophores were studied in the presence of different concentrations of free iron in vitro with M. smegmatis and virulent, avirulent and low virulent strains of M. tuberculosis. Increase in the concentrations of iron caused an appreciable increase in the growth (as assessed by cell dry-weight and log viable counts) of all 4 strains. This was, however accompanied by a significant decrease in the production of both exochelins and mycobactins, suggesting that these siderophores are necessary only under iron-deficient conditions. The growth and production of siderophores were significantly higher with the virulent strain of M.tuberculosis than with the avirulent (or) the low virulent strains

Effect of Anti-tuberculosis Drugs on the Iron- Sequestration Mechanisms of Mycobacteria

The effect of sub-lethal concent-rations of isoniazid, ethambutol, rifampicin and pyrazinamide on the growth in vitro and the production of both exochelins and mycobactins by the high virulent and the South Indian low virulent strains of M. tuberculosis was examined under iron-deficient and iron-rich conditions. There was a marked decrease in the growth of both strains in the presence of increasing concentrations of all four drugs, the inhibition being total in the presence of minimal inhibitory concentrations of the drugs. It was also observed that the growthinhibitory effect of all four drugs was slightly reversed in the presence of high concentration of iron in the medium. A significant increase was observed in the concentrations of both siderophores in the presence of all four drugs, under both iron-deficient (or) iron-rich conditions

Importance of transboundary transport of biomass burning emissions to regional air quality in Southeast Asia during a high fire event

10.5194/acp-15-363-2015Atmospheric Chemistry and Physics151363-37

Manurial value of byproducts of bio-diesel feed stocks on finger millet grain and dry fodder productivity

A replicated field experiment was conducted at Agricultural Research Station (ARS), Madenur located in Hassan District, Karnataka in rainy season during 2007 to assess the manurial value of by-products of bio-diesel feed stocks-pongamia and neem oil seed cakes vis-à-vis conventional plant nutrients sources (combination of farm yard manure and inorganic fertilizers) on the grain and fodder productivity of finger millet, the staple food cereal of southern Karnataka. Grain and dry fodder productivity of finger millet crop grown using pongamia and neem seedoil cakes is comparable to that grown using conventional plant nutrient sources. Application of plant nutrients only through pongamia and neem seed oil cakes resulted in higher available soil Nitrogen, Potassium and Organic Carbon contents

Manurial value of byproducts of bio-diesel feed stocks on finger millet grain and dry fodder productivity

A replicated field experiment was conducted at Agricultural Research Station (ARS), Madenur located in Hassan District, Karnataka in rainy season during 2007 to assess the manurial value of by-products of bio-diesel feed stocks-pongamia and neem oil seed cakes vis-à-vis conventional plant nutrients sources (combination of farm yard manure and inorganic fertilizers) on the grain and fodder productivity of finger millet, the staple food cereal of southern Karnataka. Grain and dry fodder productivity of finger millet crop grown using pongamia and neem seedoil cakes is comparable to that grown using conventional plant nutrient sources. Application of plant nutrients only through pongamia and neem seed oil cakes resulted in higher available soil Nitrogen, Potassium and Organic Carbon contents

Strong sea surface cooling in the eastern equatorial Pacific and implications for Galápagos Penguin conservation

Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 42 (2015): 6432–6437, doi:10.1002/2015GL064456.The Galápagos is a flourishing yet fragile ecosystem whose health is particularly sensitive to regional and global climate variations. The distribution of several species, including the Galápagos Penguin, is intimately tied to upwelling of cold, nutrient-rich water along the western shores of the archipelago. Here we show, using reliable, high-resolution sea surface temperature observations, that the Galápagos cold pool has been intensifying and expanding northward since 1982. The linear cooling trend of 0.8°C/33 yr is likely the result of long-term changes in equatorial ocean circulation previously identified. Moreover, the northward expansion of the cold pool is dynamically consistent with a slackening of the cross-equatorial component of the regional trade winds—leading to an equatorward shift of the mean position of the Equatorial Undercurrent. The implied change in strength and distribution of upwelling has important implications for ongoing and future conservation measures in the Galápagos.K.B.K. acknowledges support from the Alfred P. Sloan Foundation, the James E. and Barbara V. Moltz Fellowship administered by the Woods Hole Oceanographic Institution (WHOI) Ocean and Climate Change Institute (OCCI), and the National Science Foundation (NSF) Physical Oceanography program (grant OCE–1233282). S.J. acknowledges support from WHOI. C.W.B. was supported by the NOAA Center for Satellite Applications and Research.2016-02-0