Inverse-scattering theory and the density perturbations from inflation

We show how to use inverse-scattering theory as the basis for the inflationary reconstruction program, the goal of which is to gain information about the physics which drives inflation. Inverse-scattering theory provides an effective and well-motivated procedure, having a sound mathematical basis and being of sufficient generality that it can be considered the foundation for a nonparametric reconstruction program. We show how simple properties of the power spectrum translate directly into statements about the evolution of the background geometry during inflation.     

Conformational preference in thiophene-2-carbaldehyde

The 100 MHz ¹H NMR spectra of thiophene-2-carbaldehyde have been obtained in different solvents and analysed. It was found that the SO-cis conformation is more stable in all solvents, and that the proportion of the SO-trans population increases with decreasing polarity of the solvent. CNDO/2 calculations predict that the SO-cis is more stable than the SO-trans conformation. The aldehyde coupling to the ring was calculated by the CNDO/2 method and compared with the experimental value.     

Nonlinear and nonequilibrium dynamics in geomaterials

The transition from linear to nonlinear dynamical elasticity in rocks is of considerable interest in seismic wave propagation as well as in understanding the basic dynamical processes in consolidated granular materials. We have carried out a careful experimental investigation of this transition for Berea and Fontainebleau sandstones. Below a well-characterized strain, the materials behave linearly, transitioning beyond that point to a nonlinear behavior which can be accurately captured by a simple macroscopic dynamical model. At even higher strains, effects due to a driven nonequilibrium state, and relaxation from it, complicate the characterization of the nonlinear behavior.     

Quantum feedback control of atomic motion in an optical cavity

We study quantum feedback cooling of atomic motion in an optical cavity. We design a feedback algorithm that can cool the atom to the ground state of the optical potential with high efficiency despite the nonlinear nature of this problem. An important ingredient is a simplified state-estimation algorithm, necessary for a real-time implementation of the feedback loop. We also describe the critical role of parity dynamics in the cooling process and present a simple theory that predicts the achievable steady-state atomic energies.     

Quantum Zeno and anti-Zeno paradoxes

Continuous observation of a time independent projection operator is known to prevent change of state (the quantum Zeno paradox). We discuss the recent result that generic continuous measurement of time dependent projection operators will in fact ensure change of state: an anti-Zeno paradox.     

Synthesis of 5-amino-1,3,4-thiadiazoles containing dithiocarbamate groups

Synthesis of alkyl ((5-[alkylamino]-1,3,4-thiadiazol-2-yl)methyl)carbamodithioates via the reaction of glycine-based dithiocarbamates with thiosemicarbazides in the presence of POCl₃ in ethanol is disclosed. The main advantages of this method including the use of ethanol as solvent, no need to column chromatography for purification and high to excellent yields of products are noteworthy.     

Photoinduced Anisotropy in Poly(Methyl Methacrylate)/Sudan Red III Thin Films

The dynamic behavior of photoinduced optical anisotropy of amorphous PMMA/Sudan Red III thin films has been investigated using the pump-probe method. The results showed that the anisotropy increased rapidly in an exponential fashion in the first seconds of pumping, so that a photostationary state was reached as a result of the photoisomerization process cycles. The anisotropy relaxation phase decreased exponentially in a slow manner, which means the anisotropy did not disappear instantaneously when the irradiation was switched off. Evidence of the existence of the Angular Hole Burning (AHB) and the Angular Redistribution (AR) effects in the Sudan Red III molecules in the PMMA polymeric host is presented. The relative photoinduced optical anisotropy was calculated. The results showed that, at room temperature, the thermal isotropic relaxation of the photoisomer was negligible compared to the anisotropic reverse photoisomerization that occurred as soon as the pump beam was cut-off.     

Environment assisted energy transfer in dimer system

The influence of collective and multilocal environments on the energy transfer between the levels of a dimer is studied. The dynamics of energy transfer are investigated by considering coupling of collective environment with the levels of the dimer in the presence of both two individuals and mutually correlated multilocal environments. It is shown that every way of coupling we consider assists, though differently, the probability of transition between the levels of dimer. The probability of transition is strongly enhanced when the two local environments are mutually correlated.