Gauge/string duality in confining theories

This is the content of a set of lectures given at the “XIII Jorge André Swieca Summer School on Particles and Fields”, Campos do Jordão, Brazil in January 2005. They intend to be a basic introduction to the topic of gauge/gravity duality in confining theories. We start by reviewing some key aspects of the low energy physics of non‐Abelian gauge theories. Then, we present the basics of the AdS/CFT correspondence and its extension both to gauge theories in different spacetime dimensions with sixteen supercharges and to more realistic situations with less supersymmetry. We discuss the different options of interest: placing D–branes at singularities and wrapping D–branes in calibrated cycles of special holonomy manifolds. We finally present an outline of a number of non‐perturbative phenomena in non‐Abelian gauge theories as seen from supergravity.     

Electronic Structures of Highly Symmetrical Compounds of f Elements. 34 [1] Synthesis and Spectroscopic Characterization of Biscyclohexylisocyanide Adducts derived from the Tris(bis(trimethylsilyl)amido)lanthanide(III) Moiety as well as Crystal,Molecular, and Electronic Structure of the Corresponding Neodymium Compound

The reaction of tris(bis(trimethylsilyl)amido)lanthanide(III) (Ln(btmsa)₃) with two equiv. of cyclohexylisocyanide gives good yields of complexes of composition Ln(btmsa)₃(CNC₆H₁₁)₂ (Ln = Y( 1 ), La( 2 ), Ce( 3 ), Pr( 4 ), Nd( 5 ), Sm( 6 ), Eu( 7 ), Tb( 8 ), Dy( 9 ), Ho( 10 ), Tm( 11 ) and Yb( 12 )). Complex 5 crystallizes in the monoclinic space group C2/c with a = 25.689(8) Å, b = 12.165(2) Å, c = 17.895(15) Å, β = 122.47 (2)°, V = 4718.07 ų, Z = 4 and R = 0.0342. The structure of compound 5 shows the five‐coordinate Nd³⁺ ion in a nearly exact trigonal bipyramidal environment with two CNC₆H₁₁ molecules in the axial and the three btmsa ligands in the equatorial positions. The linear dichroism spectrum of a single crystal of complex 5 was measured at room temperature, and the absorption spectrum of powdered material at low temperatures. From the spectra obtained a truncated crystal field (CF) splitting pattern is derived, and simulated by fitting the parameters of a phenomenological Hamiltonian. For 80 assignments a reduced r.m.s. deviation of 20.7 cm^—1 is achieved. Making use of the calculated wavefunctions and eigenvalues the experimentally determined temperature dependence of μ²_eff could be reproduced by adopting an orbital reduction factor k = 0.991, and on the basis of the CF parameters used the experimentally oriented non‐relativistic molecular orbital scheme of compound 5 is set up.     

Bioconcentration of zinc and its effect on the biochemical constituents of the gill tissues of Labeo rohita: An FT-IR study

In the present work, an attempt has been made to assess the bioconcentration and distribution of zinc on the selected organs of Labeo rohita and to study the effect of zinc exposure on the biochemical constitutions of gill tissues of L. rohita by using FT-IR Spectroscopy. The concentration pattern in the organs reveals that the liver is the prime site of metal binding and muscle accumulates least metal concentration. The accumulation profile is in the order: liver > gill > kidney > brain > bone > muscle. It has also been observed that the administration of chelating agent d-Penicillamine (DPA) reduces the zinc concentration in all tissues more effectively than the administration of the chelating agent Ethylene Diamine Tetra Acetic acid. The FT-IR spectra reveal that zinc exposure causes significant changes in the biochemical constitutions of the gill tissues. It causes an alteration in the protein secondary structures by decreasing the α-helix and increasing the β-sheet contents. Further, it has been observed that the administration of chelating agent DPA improves the protein and lipid contents in the gill tissues compared to zinc exposed tissues. This result shows that DPA is the effective chelator of zinc in reducing the body burden of L. rohita fingerlings. In conclusion, the findings of the current study suggest that zinc exposure causes significant changes in both lipids and proteins of the gill tissues, and changes the protein profile in favour of β-sheet structure.     

Arsenic-Induced Biochemical Changes in Labeo rohita Kidney: An FTIR Study

ABSTRACT

Arsenic is a toxic heavy metal that occurs naturally in water, soil, and air. It is widespread in the environment as a consequence of both anthropogenic and natural processes. In the current study, an attempt has been made to analyze the arsenic-induced molecular changes in macromolecular components like proteins and lipids in the kidney tissues of edible fish Labeo rohita using Fourier transform infrared (FTIR) spectroscopy. The FTIR spectrum of kidney tissue is quite complex and contains several bands arising from the contribution of different functional groups. The detailed spectral analyses were performed in three distinct wave number regions, namely 3600–3050 cm^?1, 3050–2800 cm^?1, and 1800–800 cm^?1. The current study shows that the kidney tissues are more vulnerable to arsenic intoxication. FTIR spectra reveal significant differences in both absorbance intensities and areas between control and arsenic-intoxicated kidney tissues; this result indicates that arsenic intoxication induces significant alteration on the major biochemical constituents such as lipids and proteins and leads to compositional and structural changes in kidney tissues at the molecular level. The current study confirms that FTIR spectroscopy can be successfully applied to toxicologic and biological studies.     

Vibrational spectroscopy of structural defects in oligothiophenes

Vibrational spectra of oligothiophenes with structural defects are calculated within the density-functional-theory methodology. The effects of the defective αβ linkages on the infrared (IR) and Raman spectra are characterized from calculations of all isomers up to the hexamer. The signatures of αβ linked monomers can be found in IR spectra from broken symmetry arguments which result in absorptions localized in the defective region. The positions of the absorption peaks in the Raman spectra seem to be unaffected by the presence of such defects; however, strong reductions in the intensities are observed because of the shortening of the conjugation length.     

Lie-algebra expansions, Chern–Simons theories and the Einstein–Hilbert Lagrangian

Starting from gravity as a Chern–Simons action for the AdS algebra in five dimensions, it is possible to modify the theory through an expansion of the Lie algebra that leads to a system consisting of the Einstein–Hilbert action plus non-minimally coupled matter. The modified system is gauge invariant under the Poincaré group enlarged by an Abelian ideal. Although the resulting action naively looks like general relativity plus corrections due to matter sources, it is shown that the non-minimal couplings produce a radical departure from GR. Indeed, the dynamics is not continuously connected to the one obtained from Einstein–Hilbert action. In a matter-free configuration and in the torsionless sector, the field equations are too strong a restriction on the geometry as the metric must satisfy both the Einstein and pure Gauss–Bonnet equations. In particular, the five-dimensional Schwarzschild geometry fails to be a solution; however, configurations corresponding to a brane-world with positive cosmological constant on the worldsheet are admissible when one of the matter fields is switched on. These results can be extended to higher odd dimensions.     

Near stabilization of the Ce moment upon dilution in (Ce,La)Al3

Susceptibility measurements taken for 1.5 ≤ T ≤ 17 K on the system Ce_xLa_1?xAl₃ indicate that the Ce moment is nearly stabilized on dilution. Evidence for this is the fact that the fractional occupancy of the 4f¹ configuration and the spin correlation time both increase as x → 0. Crystalline electric fields influence the susceptibility of these valence fluctuation systems.