Holographic boundary actions in AdS3/CFT2 revisited

The generating functional of stress tensor correlation functions in two-dimensional conformal field theory is the nonlocal Polyakov action, or equivalently, the Liouville or Alekseev-Shatashvili action. I review its holographic derivation within the AdS3/CFT2 correspondence, both in metric and Chern-Simons formulations. I also provide a detailed comparison with the well-known Hamiltonian reduction of three-dimensional gravity to a flat Liouville theory, and conclude that the two results are unrelated. In particular, the flat Liouville action is still off-shell with respect to bulk equations of motion, and simply vanishes in case the latter are imposed. The present study also suggests an interesting re-interpretation of the computation of black hole spectral statistics recently performed by Cotler and Jensen as that of an explicit averaging of the partition function over the boundary source geometry, thereby providing potential justification for its agreement with the predictions of a random matrix ensemble.

Interlinkages Between Total Nitrogen and DOC Levels at an Urban Site of Saharsa District of Bihar (India)

Nitrogen is an element essential for building fundamental blocks of life. When present in excess amount in air, it causes adverse effects for the environment and human health.Different air pollutants when scavenged through rains are deposited on the surface. The chemical composition of rain water is an indicator of the levels of different air pollutants in the region. The present study reports the concentrations of Dissolved Organic Carbon (DOC) and the reactive nitrogen species (NO3- and NH4+) in rain water at an urban site located in the Saharsa district of Bihar. The sampling was carried out during July 2018 to October 2018.Total 18 samples were collected during this period. Results showed that the concentration of NO3- was considerably higher (2.91 mg/L)ranging from 0.26 to 11.84 mg/L than the NH4+(0.84 mg/L) ranging from 0.00 to 3.2 mg/L.The pH value in the samples ranged from 5.50 to 7.68 with a mean value of 6.52.The DOC in rain water has been estimated by using the Shimadzu TOC analyzer. Apart from DOC, total carbon (TC), total nitrogen (TN) & inorganic carbon (IC) have also been also analyzed by Shimadzu TOC analyzer. The results showed that both anthropogenic and natural sources contributed to the dissolved organic carbon (DOC) in rain water. The linkages between the sources and the transformations of gaseous NH3 with DOC have been established considering the fact that most of TN is represented by NH3.Airmass back trajectory analysis showed that the site has trans-boundary source influence from Bay of Bengal and Bangladesh. The study suggests that there is need of continuous monitoring of these parameters in air in order to notice any impact on human health, soil and vegetation.

Reconstruction of a passive tracer boundary source in an open water area

Marine pollution is one of the most serious environmental problems nowadays. Identification of sources of contaminants is among the main objectives of environmental researchers. In such problems pollutants are sometimes considered as passive tracers. In this paper, a problem of detecting and localization of the passive tracer boundary sources in an open water area is considered. A mathematical model of the sea surface pollution spread based on the system of linear unsteady convection-diffusion-reaction equations is used. The inverse problem of restoring the pollution sources on the domain boundary is formulated under the consideration that the pollution concentration data are given. The method based on the theory of adjoint equations and optimal control is used. The iterative algorithm for the solution of the problem is proposed. The article presents the results of the numerical experiment on application of the proposed algorithm to the problem of recovering pollution sources on the Black Sea coastline.