How restricting carbon dioxide and methane emissions would affect the Indian economy

India and China contain about 40 percent of the earth's people. They are at an early stage of economic development, and their increasingly massive energy requirements will depend heavily on coal, a potent source of carbon dioxide, a powerful and long-lasting greenhouse gas. India also has important sources and uses of hydroelectric and nuclear power, petroleum, and natural gas. Agriculture still produces about 30 percent of its gross domestic product, and about 72 percent of the population lives in rural areas - with their large animal populations and substantial forest acreage. India has vast cities and an industrial sector that is large in absolute terms, although it represents only 30 percent of the economy. The model developed to analyze the economic effects of constraints on greenhouse gas emissions is a multisectoral, intertemporal linear programming model, driven by the optimization of the welfare of a representative consumer. A comprehensive model was built not to project the future at a single stroke but to begin to answer questions of a"What if?"form. The results strongly suggest that the economic effects on India of such constraints would be profound. The implications of different forms of emissions restrictions - annual, cumulative, and radiative forcing - deserve more attention. Cumulative restrictions - or better still, restrictions on radiative forcing - are closely related to public policy on greenhouse effects. Such restrictions also provide significant additional degrees of freedom for the economic adjustments required. They do this, in part, by allowing the postponement of emissions restrictions, which is not permitted by annual constraints. Of course, the question arises whether a country, having benefited from postponing a required reduction in emissions, would then be willing to face the consequences in economic losses. Might there be a genuine preference - albeit an irrational one - for taking the losses annually? Would compliance with international agreements for emissions restrictions be more likely if they required annual, rather than cumulative, reductions? Monitoring requirements would be the same in either case; if effective monitoring were carried out, it would detect departures from cumulative or radiative forcing constraints just as easily as departures from annualconstraints.Environmental Economics&Policies,Carbon Policy and Trading,Montreal Protocol,Transport and Environment,Energy and Environment

Growth and welfare losses from carbon emissions restrictions : a general equilibrium analysis for Egypt

The authors assess the economic effects in Egypt, under various conditions, of restricting carbon dioxide emissions. They use their model to assess the sensitivity of these effects to alternative specifications: changes in the level or timing of restrictions, changes in the rate of discount of future welfare, and the presence or absence of alternative technologies for generating power. They also analyze a constraint on accumulated emissions of carbon dioxide. Their time model has a time horizon of 100 years, with detailed accounting for every five years, so they can be specific about differences between short- and long-run effects and their implications. However, the results reported here cover only a 60-year period - and are intended only to compare the results of generic,"what if?"questions, not as forecasts. In that 60-year period, the model economy substantially depletes its hydrocarbon reserves, which are the only non produced resource. The authors find that welfare losses due to the imposition of annual restrictions on the rate of carbon dioxide emissions are substantial - ranging from 4.5 percent for a 20 percent reduction in annual carbon dioxide emissions to 22 percent for a 40 percent reduction. The effects of the annual emissions restrictions are relatively nonlinear. The timing of the restrictions is significant. Postponing them provides a longer period for adjustment and makes it possible to continue delivering consumption goodsin a relatively unconstrained manner. The form of emissions restrictions is also important. Welfare losses are much higher when constraints are imposed on annual emissions rates rather than on total additions to the accumulation of greenhouse gases. Conventional backstop technologies for maintaining output and consumption - cogeneration, nuclear power, and gas-powered transport - are more significant than unconventional"renewable"technologies, which cannot compete for cost.Environmental Economics&Policies,Energy and Environment,Carbon Policy and Trading,Montreal Protocol,Climate Change

Transverse instability and its long-term development for solitary waves of the (2+1)-Boussinesq equation

The stability properties of line solitary wave solutions of the (2+1)-dimensional Boussinesq equation with respect to transverse perturbations and their consequences are considered. A geometric condition arising from a multi-symplectic formulation of this equation gives an explicit relation between the parameters for transverse instability when the transverse wavenumber is small. The Evans function is then computed explicitly, giving the eigenvalues for transverse instability for all transverse wavenumbers. To determine the nonlinear and long time implications of transverse instability, numerical simulations are performed using pseudospectral discretization. The numerics confirm the analytic results, and in all cases studied, transverse instability leads to collapse.Comment: 16 pages, 8 figures; submitted to Phys. Rev.

Interaction between toothbrushes and toothpaste abrasive particles in simulated tooth cleaning

There are currently many toothbrush designs on the market incorporating different filament configurations such as filaments at various angles and different lengths and made from several different materials. In order to understand how the tooth cleaning process occurs there is a need to investigate in detail how the abrasive particles in a toothpaste interact with the filaments in a teeth cleaning contact and cause material removal from a plaque or stain layer. The following describes the development of optical apparatus to enable the visualisation of simulated teeth cleaning contacts. Studies have been carried out using the apparatus to investigate particle entrainment into the contact and how it differs with varying bristle configurations. The effects of filament stiffness and tip shape were also investigated. Various types of electric toothbrushes were also tested. The studies have shown how particles are trapped at the tips of toothbrush filaments. Particles, suspended in fluid, approach the filament tips, as they pass through they may become trapped. Greater particle entrainment into the filament tip contact occurs with a reciprocating action at low filament loads and deflections than with a sliding motion. Large particles are less likely to enter tip contacts and are trapped between tips or under the filament bend at higher loads. Whether the particles are likely to be trapped and how long they remain so depends on the filament stiffness and degree of splay on loading and the filament configuration. The direction the filaments point in, the number of filaments in a tuft, the spacing of the tufts and the way the filaments splay when deflected all have an influence on entrainment of particles. Tufts with tightly packed stiff filaments which deflected together on loading were more effective at trapping particles than more flexible filaments that splayed out on loading as they present more of a barrier to particle entry and exit from the tip region

Hidden Symmetries and Integrable Hierarchy of the N=4 Supersymmetric Yang-Mills Equations

We describe an infinite-dimensional algebra of hidden symmetries of N=4 supersymmetric Yang-Mills (SYM) theory. Our derivation is based on a generalization of the supertwistor correspondence. Using the latter, we construct an infinite sequence of flows on the solution space of the N=4 SYM equations. The dependence of the SYM fields on the parameters along the flows can be recovered by solving the equations of the hierarchy. We embed the N=4 SYM equations in the infinite system of the hierarchy equations and show that this SYM hierarchy is associated with an infinite set of graded symmetries recursively generated from supertranslations. Presumably, the existence of such nonlocal symmetries underlies the observed integrable structures in quantum N=4 SYM theory.Comment: 24 page

Antiferromagnetic and van Hove Scenarios for the Cuprates: Taking the Best of Both Worlds

A theory for the high temperature superconductors is proposed. Holes are spin-1/2, charge e, quasiparticles strongly dressed by spin fluctuations. Based on their dispersion, it is claimed that the experimentally observed van Hove singularities of the cuprates are likely originated by antiferromagnetic (AF) correlations. From the two carriers problem in the 2D t-J model, an effective Hamiltonian for holes is defined with %no free parameters. This effective model has superconductivity in the ${\rm d_{x^2-y^2}}$ channel, a critical temperature ${\rm T_c \sim 100K}$ at the optimal hole density, ${\rm x=0.15}$, and a quasiparticle lifetime linearly dependent with energy. Other experimental results are also $quantitatively$ reproduced by the theory.Comment: 12 pages, 4 figures (on request), RevTeX (version 3.0), preprint NHMF

Existence of a Meromorphic Extension of Spectral Zeta Functions on Fractals

We investigate the existence of the meromorphic extension of the spectral zeta function of the Laplacian on self-similar fractals using the classical results of Kigami and Lapidus (based on the renewal theory) and new results of Hambly and Kajino based on the heat kernel estimates and other probabilistic techniques. We also formulate conjectures which hold true in the examples that have been analyzed in the existing literature

Structured machine learning tools for modelling characteristics of guided waves

The use of ultrasonic guided waves to probe the materials/structures for damage continues to increase in popularity for non-destructive evaluation (NDE) and structural health monitoring (SHM). The use of high-frequency waves such as these offers an advantage over low-frequency methods from their ability to detect damage on a smaller scale. However, in order to assess damage in a structure, and implement any NDE or SHM tool, knowledge of the behaviour of a guided wave throughout the material/structure is important (especially when designing sensor placement for SHM systems). Determining this behaviour is extremely difficult in complex materials, such as fibre–matrix composites, where unique phenomena such as continuous mode conversion takes place. This paper introduces a novel method for modelling the feature-space of guided waves in a composite material. This technique is based on a data-driven model, where prior physical knowledge can be used to create structured machine learning tools; where constraints are applied to provide said structure. The method shown makes use of Gaussian processes, a full Bayesian analysis tool, and in this paper it is shown how physical knowledge of the guided waves can be utilised in modelling using an ML tool. This paper shows that through careful consideration when applying machine learning techniques, more robust models can be generated which offer advantages such as extrapolation ability and physical interpretation

A Bayesian method for material identification of composite plates via dispersion curves

Ultrasonic guided waves offer a convenient and practical approach to structural health monitoring and non-destructive evaluation. A key property of guided waves is the fully defined relationship between central frequency and propagation characteristics (phase velocity, group velocity and wavenumber)—which is described using dispersion curves. For many guided wave-based strategies, accurate dispersion curve information is invaluable, such as group velocity for localisation. From experimental observations of dispersion curves, a system identification procedure can be used to determine the governing material properties. As well as returning an estimated value, it is useful to determine the distribution of these properties based on measured data. A method of simulating samples from these distributions is to use the iterative Markov-Chain Monte Carlo (MCMC) procedure, which allows for freedom in the shape of the posterior. In this work, a scanning-laser Doppler vibrometer is used to record the propagation of Lamb waves in a unidirectional-glass-fibre composite plate, and dispersion curve data for various propagation angles are extracted. Using these measured dispersion curve data, the MCMC sampling procedure is performed to provide a Bayesian approach to determining the dispersion curve information for an arbitrary plate. The distribution of the material properties at each angle is discussed, including the inferred confidence in the predicted parameters. The percentage errors of the estimated values for the parameters were 10–15 points larger when using the most likely estimates, as opposed to calculating from the posterior distributions, highlighting the advantages of using a probabilistic approach

Thermodynamic Properties of the Dimerised and Frustrated S=1/2 Chain

By high temperature series expansion, exact diagonalisation and temperature density-matrix renormalisation the magnetic susceptibility $\chi(T)$ and the specific heat $C(T)$ of dimerised and frustrated $S=1/2$ chains are computed. All three methods yield reliable results, in particular for not too small temperatures or not too small gaps. The series expansion results are provided in the form of polynomials allowing very fast and convenient fits in data analysis using algebraic programmes. We discuss the difficulty to extract more than two coupling constants from the temperature dependence of $\chi(T)$.Comment: 14 pages, 13 figures, 4 table