We construct cosmological spacetimes with null Kasner-like singularities as purely gravitational solutions with no other background fields turned on. These can be recast as anisotropic plane-wave spacetimes by coordinate transformations. We analyse string quantization to find the spectrum of string modes in these backgrounds. The classical string modes can be solved for exactly in these time-dependent backgrounds, which enables a detailed study of the near singularity string spectrum, (time-dependent) oscillator masses and wavefunctions. We find that for low lying string modes(finite oscillation number), the classical near-singularity string mode functions are non-divergent for various families of singularities. Furthermore, for any infinitesimal regularization of the vicinity of the singularity, we find a tower of string modes of ultra-high oscillation number which propagate essentially freely in the background. The resulting picture suggests that string interactions are non-negligible near the singularity.Comment: Latex, 30pgs; v2. minor clarifications, references adde

We study local operators of U (N )×U (N ) N = 6 Chern-Simons-matter theory including a class of magnetic monopole operators. To take into account the interaction of monopoles and basic fields for large Chern-Simons level k, we consider the appropriate perturbation theory in 1 k which reliably describes small excitations around protected chiral operators. We also compute the superconformal index with some simple monopole operators and show that it agrees with the recent result obtained from localization. For this agreement, it is crucial that excitations of gauge fields and some matter scalars mix, which is described classically by odd dimensional self-duality like equations.

In the present scenario aluminium is an useful metal due its admirable properties such as light weight, low cost and excellent thermal conductivity.In order to take advantages of these properties aluminium is being used to make the metal matrix composites for tribological application, In this present investigation effort has been made to assess the wear properties of Al–B4C–Gr metal matrix composite at various temperatures such as 323° K, 373° K and 423° K. Al–B4C–Gr Hybrid metal matrix composites were fabricated by stir casting technique. The influence of parameters like load, speed, distance and temperature on the wear rate was investigated. A plan of experiments, based on Taguchi model with L27 orthogonal array and analysis of variance was employed to investigate the influence of process parameters on the wear behaviour of these hybrid metal matrix composites. The wear resistance increased with increasing temperature, but wear resistance decreased at higher loads. It was observed that the abrasive wear is dominates while sliding as observed by SEM analysis of worn out specimens.

We look for chiral primaries in the general Leigh-Strassler deformed N = 4 super Yang-Mills theory by systematically computing the planar one-loop anomalous dimension for single trace operators up to dimension six. The operators are organised into representations of the trihedral group, ∆(27), which is a symmetry of the Lagrangian. We find an interesting relationship between the U (1) R -charge of chiral primaries and the representation of ∆(27) to which the operator belongs. Up to scaling dimension ∆ 0 = 6 (and conjecturally to all dimensions) the following holds: The planar one-loop anomalous dimension vanishes only for operators that are in the singlet or three dimensional representations of ∆(27). For other operators, the vanishing of the one-loop anomalous dimension occurs only in a sub-locus in the space of couplings. *

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