396 research outputs found
Petrology and physical conditions of metamorphism of calcsilicate rocks from low- to high-grade transition area, Dharmapuri District, Tamil Nadu
Calc-silicate rocks comprising quartz, plagioclase, diopside, sphene, scapolite, grossularite-andradite and wollastonite occur as lensoid enclaves within the greasy migmatitic and charnockitic gneisses of the Archaean amphibolite- to granulite-facies transition zone in Dharmapuri district, Tamil Nadu. The calc-silicate rocks are characterized by the absence of K-feldspar and primary calcite, presence of large modal quartz and plagioclase and formation of secondary garnet and zoisite rims around scapolite and wollastonite. The mineral distributions suggest compositional layering. The chemical composition and mineralogy of the calc-silicate rocks indicate that they were derived from impure silica-rich calcareous sediments whose composition is similar to that of pelite-limestone mixtures. From the mineral assemblages the temperature, pressure and fluid composition during metamorphism were estimated. The observed mineral reaction sequences require a range of X sub CO2 values demonstrating that an initially CO2-rich metamorphic fluid evolved with time towards considerably more H2O-rich compositions. These variations in fluid composition suggest that there were sources of water-rich fluids external to the calc-silicate rocks and that mixing of these fluids with those of calc-silicate rocks was important in controlling fluid composition in calc-silicate rocks and some adjacent rock types as well
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Theoretical Examination of Transfer Cavities in a Standing-wave Free-electron Laser Two-beam Accelerator
Farmer producer companies : past, present and future
Eighty-seven percent of agricultural households in India are small and marginal
producers, cultivating small plots which generate low returns. Their average
monthly income is Rs 6426, making farming on small plots economically unviable
(NSSO 2014). Therefore, policy makers and practitioners are turning to producer
collectives as a means for improving the economic situation of small producers
Deformation effects in Ni nuclei produced in Si+Si at 112 MeV
Velocity and energy spectra of the light charged particles (protons and
-particles) emitted in the Si(E = 112 MeV) + Si
reaction have been measured at the Strasbourg VIVITRON Tandem facility. The
ICARE charged particle multidetector array was used to obtain exclusive spectra
of the light particles in the angular range 15 - 150 degree and to determine
the angular correlations of these particles with respect to the emission angles
of the evaporation residues. The experimental data are analysed in the
framework of the statistical model. The exclusive energy spectra of
-particles emitted from the Si + Si compound system are
generally well reproduced by Monte Carlo calculations using spin-dependent
level densities. This spin dependence approach suggests the onset of large
deformations at high spin. A re-analysis of previous -particle data
from the Si + Si compound system, using the same spin-dependent
parametrization, is also presented in the framework of a general discussion of
the occurrence of large deformation effects in the A ~ 60 mass region.Comment: 25 pages, 6 figure
Confinement and electron correlation effects in photoionization of atoms in endohedral anions: Ne@C60^{z-}
Trends in resonances, termed confinement resonances, in photoionization of
atoms A in endohedral fullerene anions A@C60^{z-} are theoretically studied and
exemplified by the photoionization of Ne in Ne@C{60}^{z-}. Remarkably, above a
particular nl ionization threshold of Ne in neutral Ne@C60 (I_{nl}^{z=0}),
confinement resonances in corresponding partial photoionization cross sections
sigma_{nl} of Ne in any charged Ne@C60^{z-} remain almost intact by a charge z
on the carbon cage, as a general phenomenon. At lower photon energies, omega <
I_{nl}^{z=0}, the corresponding photoionization cross sections develop
additional, strong, z-dependent resonances, termed Coulomb confinement
resonances, as a general occurrence. Furthermore, near the innermost 1s
ionization threshold, the 2p photoionization cross section sigma_{2p} of the
outermost 2p subshell of thus confined Ne is found to inherit the confinement
resonance structure of the 1s photoionization spectrum, via interchannel
coupling. As a result, new confinement resonances emerge in the 2p
photoionization cross section of the confined Ne atom at photoelectron energies
which exceed the 2p threshold by about a thousand eV, i.e., far above where
conventional wisdom said they would exist. Thus, the general possibility for
confinement resonances to resurrect in photoionization spectra of encapsulated
atoms far above thresholds is revealed, as an interesting novel general
phenomenon.Comment: 6 pages, 4 figures, Latex2e, jpconf.cls styl
Refined procedures for accurate determination of solution structures of nucleic acids by two dimensional nuclear magnetic resonance spectroscopy
New procedures have been described for accurate determination of solution structures of nucleic acids. These are two fold; new two dimensional nuclear magnetic resonance techniques and better approaches for interpretation of nuclear magnetic resonance data for structure determination purposes. The significant development in two dimensional nuclear magnetic resonance techniques for this purpose are ω1 -scaling and recording of pure phase spectra. Use ofω1-scaled correlated and nuclear Overhauser effect spectra for estimation of interproton distances and 1H-1H coupling constants has been described. Computer simulation procedures for exact determination of structure have been described. Experimental spectra demonstrating the application of new procedures have been presented
A tracked approach for automated NMR assignments in proteins (TATAPRO)
A novel automated approach for the sequence specific NMR assignments of 1HN, 13Cα, 13Cβ, 13C'/1Hα and 15N spins in proteins, using triple resonance experimental data, is presented. The algorithm, TATAPRO (Tracked AuTomated Assignments in Proteins) utilizes the protein primary sequence and peak lists from a set of triple resonance spectra which correlate 1HN and 15N chemical shifts with those of 13Cα, 13Cβ and 13C'/1Hα. The information derived from such correlations is used to create a 'master list' consisting of all possible sets of 1HN i, 15Ni, 13Cα i, 13Cβ i, 13C'i/1Hα i, 13Cα i-1, 13Cβ i-1 and 13C'i-1/ 1Hα i-1 chemical shifts. On the basis of an extensive statistical analysis of 13Cα and 13Cβ chemical shift data of proteins derived from the BioMagResBank (BMRB), it is shown that the 20 amino acid residues can be grouped into eight distinct categories, each of which is assigned a unique two-digit code. Such a code is used to tag individual sets of chemical shifts in the master list and also to translate the protein primary sequence into an array called pps array. The program then uses the master list to search for neighbouring partners of a given amino acid residue along the polypeptide chain and sequentially assigns a maximum possible stretch of residues on either side. While doing so, each assigned residue is tracked in an array called assig array, with the two-digit code assigned earlier. The assig_array is then mapped onto the pps array for sequence specific resonance assignment. The program has been tested using experimental data on a calcium binding protein from Entamoeba histolytica (Eh-CaBP, 15 kDa) having substantial internal sequence homology and using published data on four other proteins in the molecular weight range of 18-42 kDa. In all the cases, nearly complete sequence specific resonance assignments (> 95%) are obtained. Furthermore, the reliability of the program has been tested by deleting sets of chemical shifts randomly from the master list created for the test proteins
Deformation effects in the Si+C and Si+Si reaction Search
The possible occurence of highly deformed configurations is investigated in
the Ca and Ni di-nuclear systems as formed in the
Si+C,Si reactions by using the properties of emitted light
charged particles. Inclusive as well as exclusive data of the heavy fragments
and their associated light charged particles have been collected by using the
{\sc ICARE} charged particle multidetector array. The data are analysed by
Monte Carlo CASCADE statistical-model calculations using a consistent set of
parameters with spin-dependent level densities. Significant deformation effects
at high spin are observed as well as an unexpected large Be cluster
emission of a binary nature.Comment: 3 pages latex, 2 eps figures, paper presented in "wokshop on physics
with multidetector array (pmda2000)Calcutta, India (to be published at
PRAMANA, journal of Physics, India
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