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Field-aligned currents in Saturn's magnetosphere: Local time dependence of southern summer currents in the dawn sector between midnight and noon

We examine and compare the magnetic field perturbations associated with field-aligned ionosphere-magnetosphere coupling currents at Saturn, observed by the Cassini spacecraft during two sequences of highly inclined orbits in 2006/2007 and 2008 under late southern summer conditions. These sequences explore the southern currents in the dawn-noon and midnight sectors, respectively, thus allowing investigation of possible origins of the local time (LT) asymmetry in auroral Saturn kilometric radia...

Hunt, G. J.; Cowley, Stanley W. H.; Provan, G.; Bunce, E. J.; Alexeev, I. I.... et al.

Highly branched unsaturated polyethylenes achievable using strained imino-cyclopenta[b]pyridyl-nickel precatalysts

A new family of strained imino-cyclopenta[b]pyridines, 7-(ArN)-6-Me2C8H5N (Ar = 2,6-Me2Ph (L1), 2,6-Et2Ph (L2), 2,4,6-Me3Ph (L3), 2,6-Et2-4-MePh (L4), 2,6-i-Pr2Ph (L5)), have been synthesized in reasonable yield by a sequence of reactions from 2-chloro-cyclopenta[b]pyridin-7-one. Treatment of L1 and L3 with NiCl2·6H2O generates mononuclear bis-ligated [7-(ArN)-6-Me2C8H5N]2NiCl2 (Ar = 2,6-Me2Ph (Ni1), 2,4,6-Me3Ph (Ni3)), while with L2 and L4, the chloride-bridged binuclear complexes [7-(ArN)-6...

Overview of Solar Wind–Magnetosphere–Ionosphere–Atmosphere Coupling and the Generation of Magnetospheric Currents

We review the morphology and dynamics of the electrical current systems of the terrestrial magnetosphere and ionosphere. Observations from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) over the three years 2010 to 2012 are employed to illustrate the variability of the field-aligned currents that couple the magnetosphere and ionosphere, on timescales from minutes to years, in response to the impact of solar wind disturbances on the magnetosphere and change...

Milan, S. E.; Clausen, L. B. N.; Coxon, J. C.; Carter, J. A.; Walach, M. T.... et al.

The Munali Ni sulfide deposit, southern Zambia: a multi-stage, mafic-ultramafic, magmatic sulfide-magnetite-apatite-carbonate megabreccia

The Munali Intrusive Complex (MIC) is a flattened tube-shaped, mafic-ultramafic intrusion located close to the southern Congo Craton margin in the Zambezi belt of southern Zambia. It is made up of a Central Gabbro Unit (CGU) core, surrounded by a Marginal Ultramafic-mafic Breccia Unit (MUBU), which contains magmatic Ni sulfide mineralisation. The MIC was emplaced into a sequence of metamorphosed Neoproterozoic rift sediments and is entirely hosted within a unit of marble. Munali has many of t...

Holwell, David A.; Mitchell, Chloe L.; Howe, Grace A.; Evans, David M.; Ward, Laura A.... et al.

Field spectroscopy and radiative transfer modelling to assess impacts of petroleum pollution on biophysical and biochemical parameters of the Amazon rainforest

Biophysical and biochemical plant foliage parameters play a key role in assessing vegetation health. Those plant parameters determine the spectral reflectance and transmittance properties of vegetation; therefore, hyperspectral remote sensing, particularly imaging spectroscopy, can provide estimates of leaf and canopy chemical properties. Based on the relationship between spectral response and biochemical/biophysical properties of the leaves and canopies, the PROSPECT radiative transfer model...

Arellano, Paul; Tansey, Kevin; Balzter, Heiko; Boyd, Doreen S.

A dissipative force between colliding viscoelastic bodies: Rigorous approach

A collision of viscoelastic bodies is analysed within a mathematically rigorous approach. We develop a perturbation scheme to solve continuum mechanics equation, which deals simultaneously with strain and strain rate in the bulk of the bodies' material. We derive dissipative force that acts between particles and express it in terms of particles' deformation, deformation rate and material parameters. It differs noticeably from the currently used dissipative force, found within the quasi-static...

Brilliantov, Nikolay V.; Pimenova, Anastasiya V.; Goldobin, Denis S.

A Generalist Predator Regulating Spread of a Wildlife Disease: Exploring Two Infection Transmission Scenarios

Ecoepidemiology is a well-developed branch of theoretical ecology, which explores interplay between the trophic interactions and the disease spread. In most ecoepidemiological models, however, the authors assume the predator to be a specialist, which consumes only a single prey species. In few existing papers, in which the predator was suggested to be a generalist, the alternative food supply was always considered to be constant. This is obviously a simplification of reality, since predators ...

Sen, M.; Banerjee, M.; Morozov, A.

Modelling in Ecology, Epidemiology and Ecoepidemiology: Introduction to the Special Issue

Morozov, A.

Noise-Produced Patterns in Images Constructed from Magnetic Flux Leakage Data

Magnetic flux leakage measurements help identify the position, size and shape of corrosion-related defects in steel casings used to protect boreholes drilled into oil and gas reservoirs. Images constructed from magnetic flux leakage data contain patterns related to noise inherent in the method. We investigate the patterns and their scaling properties for the case of delta-correlated input noise, and consider the implications for the method’s ability to resolve defects. The analytical evaluati...

Goldobin, D. S.; Pimenova, A. V.; Levesley, J.; Elkington, P.; Bacciarelli, M.

Magnetic Flux Leakage Method: Large-Scale Approximation

We consider the application of the magnetic flux leakage (MFL) method to the detection of defects in ferromagnetic (steel) tubulars. The problem setup corresponds to the cases where the distance from the casing and the point where the magnetic field is measured is small compared to the curvature radius of the undamaged casing and the scale of inhomogeneity of the magnetic field in the defect-free case. Mathematically this corresponds to the planar ferromagnetic layer in a uniform magnetic fie...

Pimenova, A. V.; Goldobin, D. S.; Levesley, J.; Ivantsov, A. O.; Elkington, P.... et al.

Three Waves of Chemical Dynamics

Three epochs in development of chemical dynamics are presented. We try to understand the modern research programs in the light of classical works.

Gorban, A. N.; Yablonsky, G. S.

High permeability explains the vulnerability of the carbon store in drained tropical peatlands

Tropical peatlands are an important global carbon (C) store but are threatened by drainage for palm oil and wood pulp production. The store's stability depends on the dynamics of the peatland water table, which in turn depend on peat permeability. We found that an example of the most abundant type of tropical peatland-ombrotrophic domes-has an unexpectedly high permeability similar to that of gravel. Using computer simulations of a natural peat dome (NPD) and a ditch-drained peat dome (DPD) w...

Baird, Andy J.; Low, Robert; Young, Dylan; Swindles, Graeme T.; Lopez, Omar R.... et al.

Generation of mechanical force by grafted polyelectrolytes in an electric field

We study theoretically and by means of molecular dynamics (MD) simulations the generation of mechanical force by grafted polyelectrolytes in an external electric field, which favors its adsorption on the grafting plane. The force arises in deformable bodies linked to the free end of the chain. Varying the field, one controls the length of the nonadsorbed part of the chain and hence the deformation of the target body, i.e., the arising force too. We consider target bodies with a linear force-d...

Brilliantov, N. V.; Budkov, Yu. A.; Seidel, C.

Forward-Invariant Peeling in Chemical Dynamics: a Simple Case Study

Forward-invariant peeling aims to produce forward-invariant subset from a given set in phase space. The structure of chemical kinetic equations allows us to describe the general operations of the forward-invariant peeling. For example, we study a simple reaction network with three components A1,A2,A3 and reactions A1 → A2 → A3 → A1, 2A1 ⇌ 3A2 (without any stoichiometric conservation law). We assume that kinetics obey the classical mass action law and reaction rate constants are positive inter...

Gorban, A. N.

Generalized Mass Action Law and Thermodynamics of Nonlinear Markov Processes

The nonlinear Markov processes are measure-valued dynamical systems which preserve positivity. They can be represented as the law of large numbers limits of general Markov models of interacting particles. In physics, the kinetic equations allow Lyapunov functionals (entropy, free energy, etc.). This may be considered as a sort of inheritance of the Lyapunov functionals from the microscopic master equations. We study nonlinear Markov processes that inherit thermodynamic properties from the mic...

Gorban, A. N.; Kolokoltsov, V. N.

Robustness Analysis of Feedback Linearisation for Uncertain Rational Systems

Feedback Linearisation (FL) is a nonlinear control technique that has gained a lot of attention in the past 30 years. Due to its relatively simple synthesis, the use of FL has been investigated particularly in the aerospace community, because aircraft models are often highly nonlinear and a controller is needed that can guarantee good performance over a wide range of operating conditions. However, mathematical models of real-life physical systems always have a level of uncertainty on them, as...

Norton, Peter David

Smelting condition identification for a fused magnesium furnace based on an acoustic signal

To promote energy efficiency during fused magnesium furnace smelting, four smelting states were introduced in the smelting stage: an unmelted state, semi–molten state, molten state, and overheating state. A smelting identification system to distinguish these smelting states was developed through the use of linear predictive coding and a principal component analysis algorithm. A new smelting condition identification system was obtained. Corresponding pilot productions were conducted to compare...

Fu, You; Wang, Ninghui; Wang, Zhen; Wang, Zhiqiang; Ji, Bing... et al.

The Impact of Fragmented Habitat's Size and Shape on Populations with Allee Effect

This study aims to explore the ways in which population dynamics are affected by the shape and size of fragmented habitats. Habitat fragmentation has become a key concern in ecology over the past 20 years as it is thought to increase the threat of extinction for a number of plant and animal species; particularly those close to the fragment edge. In this study, we consider this issue using mathematical modelling and computer simulations in several domains of various shape and with different st...

Alharbi, W. G.; Petrovskii, S. V.

Modelling in Ecology, Epidemiology and Ecoepidemiology: Introduction to the Special Issue

Morozov, A.; Petrovskii, S.

Fast Sampling of Evolving Systems with Periodic Trajectories

We propose a novel method for fast and scalable evaluation of periodic solutions of systems of ordinary differential equations for a given set of parameter values and initial conditions. The equations governing the system dynamics are supposed to be of a special class, albeit admitting nonlinear parametrization and nonlinearities. The method enables to represent a given periodic solution as sums of computable integrals and functions that are explicitly dependent on parameters of interest and ...

Tyukin, I. Yu.; Gorban, A. N.; Tyukina, T. A.; Al-Ameri, J. M.; Korablev, Yu. A.