On the classical central charge

In the canonical formulation of a classical field theory, symmetry properties are encoded in the Poisson bracket algebra, which may have a central term. Starting from this well understood canonical structure, we derive the related Lagrangian form of the central term.Comment: 23 pages, RevTeX, no figures; introduction improved, a few references adde

Mehanizam toksičnosti i detoksikacije organofosfornih spojeva s naglaskom na istraživanja u Hrvatskoj

This review comprises studies on the mechanisms of toxicity and detoxication of organophosphorus (OP) compounds done in Croatia in different research areas. One area is the synthesis of antidotes against OP poisoning and their in vivo testing in experimental animals. In vitro studies included in this review focus on the mechanisms of reversible inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), protection of cholinesterases from inhibition by OPs, and reactivation of phosphylated cholinesterases. The third area comprises distribution profiles of BChE and paraoxonase (PON) phenotypes in selected population groups and the detection of OPs and metabolites in humans. Finally, methods are described for the detection of OP compounds in human blood and other media by means of cholinesterase inhibitionPrikazana su istraživanja vođena u Hrvatskoj na različitim područjima mehanizma toksičnosti i detoksikacije organofosfornih (OP) spojeva. Jedno je područje sinteza antidota protiv otrovanja OP spojevima i testiranje in vivo antidota na eksperimentalnim životinjama. Istraživanja in vitro odnose se na mehanizam reverzibilne inhibicije acetilkolinesteraze (AChE) i buturilkolinesteraze (BChE), zaštitu kolinesteraza od inhibicije OP spojevima te reaktivaciju fosfiliranih kolinesteraza. Treće je područje distribucija fenotipova BChE i paraoksonaze (PON) u odabranim populacijama te detekcija OP spojeva i njihovih metabolita u ljudima. Na kraju su opisane metode detekcije OP spojeva u ljudskoj krvi i drugim medijima koje se osnivaju na inhibiciji kolinesteraza

Asymptotic dynamics in 3D gravity with torsion

We study the nature of boundary dynamics in the teleparallel 3D gravity. The asymptotic field equations with anti-de Sitter boundary conditions yield only two non-trivial boundary modes, related to a conformal field theory with classical central charge. After showing that the teleparallel gravity can be formulated as a Chern-Simons theory, we identify dynamical structure at the boundary as the Liouville theory.Comment: 16 pages, RevTeX, no figure

Theory of Two-Dimensional Josephson Arrays in a Resonant Cavity

We consider the dynamics of a two-dimensional array of underdamped Josephson junctions placed in a single-mode resonant cavity. Starting from a well-defined model Hamiltonian, which includes the effects of driving current and dissipative coupling to a heat bath, we write down the Heisenberg equations of motion for the variables of the Josephson junction and the cavity mode, extending our previous one-dimensional model. In the limit of large numbers of photons, these equations can be expressed as coupled differential equations and can be solved numerically. The numerical results show many features similar to experiment. These include (i) self-induced resonant steps (SIRS's) at voltages V = (n hbar Omega)/(2e), where Omega is the cavity frequency, and n is generally an integer; (ii) a threshold number N_c of active rows of junctions above which the array is coherent; and (iii) a time-averaged cavity energy which is quadratic in the number of active junctions, when the array is above threshold. Some differences between the observed and calculated threshold behavior are also observed in the simulations and discussed. In two dimensions, we find a conspicuous polarization effect: if the cavity mode is polarized perpendicular to the direction of current injection in a square array, it does not couple to the array and there is no power radiated into the cavity. We speculate that the perpendicular polarization would couple to the array, in the presence of magnetic-field-induced frustration. Finally, when the array is biased on a SIRS, then, for given junction parameters, the power radiated into the array is found to vary as the square of the number of active junctions, consistent with expectations for a coherent radiation.Comment: 11 pages, 8 eps figures, submitted to Phys. Rev

Conservation laws in the teleparallel theory of gravity

We study the conservation laws associated with the asymptotic Poincare symmetry of spacetime in the general teleparallel theory of gravity. Demanding that the canonical Poincare generators have well defined functional derivatives in a properly defined phase space, we obtain the improved form of the generators, containing certain surface terms. These terms are shown to represent the values of the related conserved charges: energy-momentum and angular momentum.Comment: 22 pages, RevTex, discussion of the angular momentum of the Dirac source solution corrected, twelve references adde

Incorporating Ecosystems in the Water-Energy-Food Nexus: Current Perspective and Future Directions

Integrated approaches for managing natural resources are needed to meet the increasing demand for freshwater, energy and food, while, in parallel, mitigating and adapting to climate change, maintaining the integrity of ecosystems, and ensuring equitable access to resources. The Water-Energy-Food (WEF) Nexus has been proposed as a cross-sectoral approach to understand, analyse, and manage the complex trade-offs and exploit synergies that arise among these resource sectors. Although not initially included as a component of the Nexus, the importance of ecosystems in supporting water, energy and food security is increasingly recognised by the Nexus community of researchers and practitioners. However, attempts to conceptually integrate Ecosystems into the Nexus have yet to converge into a common framework. A group of natural resources management researchers, system thinkers and ecosystem services experts from the European network COST Action CA20138 NEXUSNET have compiled and investigated the various approaches for integrating ecosystems in the WEF Nexus. By combining literature analysis with interdisciplinary workshops – one of which was held in a hybrid format (in person and online) at the University of Oulu, Finland, in September 2022 – we reveal a multiplicity of concepts utilised to represent, partially or fully, ecosystems in the Nexus, namely “natural environment”, “ecosystem services” and “biodiversity”. Disparity was also found in the role attributed to ecosystems in the Nexus framework, being it an underlying layer from which resources for Nexus sectors are extracted or the pillar of an expanded Nexus system – i.e., the WEF-Ecosystems Nexus. Through this collaborative effort, we present possible advantages and disadvantages of adopting differential WEF-Ecosystems Nexus approaches, highlighting their potential complementarity and integration to support future advancement of Nexus research. In the oral presentation, we will show our preliminary findings and encourage the exchange of ideas and feedback from the different scientific disciplines present at the CEMEPE Conference.Tenth International Conference on Environmental Management, Engineering, Planning and Economics (CEMEPE) & SECOTOX Conference organized by: Division of Hydraulics and Environmental Engineering, Department of Civil Engineering, Aristotle University of Thessaloniki and Society of Ecotoxicology and Environmental Safety (SECOTOX), Skiathos island, Greece, 2023

Preparation and photocatalyic properties of TiO2-P25 film prepared by spray pyrolysis method

TiO2 films were synthesized by immobilization of Degussa P25 powders on stainless steel support by spray pyrolysis technique. After preparation, the films were annealed at different temperatures in order to obtain materials with different morphological, structural, and textural properties. The photocatalytic activity of obtained films was investigated by monitoring the degradation of arylazo pyridone dye. The results showed that with increasing annealing temperature the photoactivity of films decreased. A comparative photocatalytic activity of the synthesized films and corresponding commercial powders was evaluated under the same experimental conditions. Films generally showed lower photoactivity than powders, due to mass transfer limitations inside film layer, smaller surface exposure to light, and possible presence of metal ions in film layer