In the causal set approach to quantum gravity, the spacetimecontinuum is replaced by a discrete substructure, the causal set, which isa locally finite poset. I will spend the first half of the talk with ageneral introduction to causal set theory. I will then discuss a 2D modelof causal set quantum gravity which overcomes the so-called entropy problemassociated with quantum geometries. In particular, 2D Minkowski spacetimeis a prediction of the theory in the large volume limit.

We outline recent advances in the quantization of noncommutativequantum field theories that preserve spacetime symmetries. This novelquantization procedure (called twisted quantization) has phenomenologicalimplications, as well as consequences for model-building in particlephysics. We explain some of these effects, like the deformation of usualspin-statistics connection at high energies.

Stable isotopes of hydrogen, carbon, nitrogen and oxygen are present in significant amounts in all the natural materials. However, their abundances are not invariant. The natural variations in stable isotopes of a given element can arise due to many factors and some of these are tractable through theoretical calculations. The change in isotope content of an element from one phase/compound to another is termed as fractionation. There are two basic mechanisms of fractionation—kinetic and equilibrium which can be linked to the nature of the associated reactions.The variations in the natural materials can be used to trace the processes undergone by these systems. Various environmental issues like pollution, global warming, changes in ocean productivity, tracing pathways of carbon cycle etc., can be addressed by measurement of the stable isotope ratios in the relevant materials. This talk will give an introduction to this subject as well as discuss some recent discoveries in this area.

Stable isotopes of hydrogen, carbon, nitrogen and oxygen are present in significant amounts in all the natural materials. However, their abundances are not invariant. The natural variations in stable isotopes of a given element can arise due to many factors and some of these are tractable through theoretical calculations. The change in isotope content of an element from one phase/compound to another is termed as fractionation. There are two basic mechanisms of fractionation—kinetic and equilibrium which can be linked to the nature of the associated reactions.The variations in the natural materials can be used to trace the processes undergone by these systems. Various environmental issues like pollution, global warming, changes in ocean productivity, tracing pathways of carbon cycle etc., can be addressed by measurement of the stable isotope ratios in the relevant materials. This talk will give an introduction to this subject as well as discuss some recent discoveries in this area.