Tradable Green Certificates as a Policy Instrument? A Discussion on the Case of Poland

Quota obligation schemes based on tradable green certificates have become a popular policy instrument to expand power generation from renewable energy sources (RES). Their application, however, can neither be justified as a first-best response to a market failure, nor, in a second-best sense, as an instrument mitigating distortionary effects of the emissions externality, if an emissions trading system exists that fully covers the energy industry. We study how ancillary reasons, in form of overcoming various barriers for RES use and establishing beneficial side-effects, such as industry development, energy security, and abatement of pollutants not covered under the ETS, apply to the scheme recently introduced in Poland. While setting substantial expansion incentives, an advantage for local industry or job-market development or energy security can hardly be seen. With rising power prices for end consumers and awareness that the extra rents from the schemes mostly accrue to foreign investors and renewable and polluting generators, we expect a negative impact on social acceptance for RES and RES deployment support policies.tradable green certificates, environmental policy, Poland, Resource /Energy Economics and Policy,

Oat variety characteristics for suppressing weeds

Oats are a valuable food source and useful in the crop rotation both in organic and conventional farming systems, partly because of their excellent weed suppression ability. Thomas Döring, Louisa Winkler and Nick Fradgley report new results that show how plant breeding can make oats even better

Bacterial swarmer cells in confinement: A mesoscale hydrodynamic simulation study

A wide spectrum of Peritrichous bacteria undergo considerable physiological changes when they are inoculated onto nutrition-rich surfaces and exhibit a rapid and collective migration denoted as swarming. Thereby, the length of such swarmer cells and their number of flagella increases substantially. In this article, we investigated the properties of individual E. coli-type swarmer cells confined between two parallel walls via mesoscale hydrodynamic simulations, combining molecular dynamics simulations of the swarmer cell with the multiparticle particle collision dynamics approach for the embedding fluid. E. coli-type swarmer cells are three-times longer than their planktonic counter parts, but their flagella density is comparable. By varying the wall separation, we analyze the confinement effect on the flagella arrangement, on the distribution of cells in the gap between the walls, and on the cell dynamics. We find only a weak dependence of confinement on the bundle structure and dynamics. The distribution of cells in the gap changes from a geometry-dominated behavior for very narrow to fluid-dominated behavior for wider gaps, where cells are preferentially located in the gap center for narrower gaps and stay preferentially next to one of the walls for wider gaps. Dynamically, the cells exhibit a wide spectrum of migration behaviors, depending on their flagella bundle arrangement, and ranges from straight swimming to wall rolling

Hydrodynamics of Binary Fluid Mixtures - An Augmented Multiparticle Collison Dynamics Approach

The Multiparticle Collision Dynamics technique (MPC) for hydrodynamics simulations is generalized to binary fluid mixtures and multiphase flows, by coupling the particle-based fluid dynamics to a Ginzburg-Landau free-energy functional for phase-separating binary fluids. To describe fluids with a non-ideal equation of state, an additional density-dependent term is introduced. The new approach is verified by applying it to thermodynamics near the critical demixing point, and interface fluctuations of droplets. The interfacial tension obtained from the analysis of the capillary wave spectrum agrees well with the results based on the Laplace-Young equation. Phase-separation dynamics follows the Lifshitz-Slyozov law

Hydrodynamics of polymers in an active bath

The conformational and dynamical properties of active polymers in solution are determined by the nature of the activity, and the behavior of polymers with self-propelled, active Brownian particle-type monomers differs qualitatively from that of polymers with monomers driven externally by colored noise forces. We present simulation and theoretical results for polymers in solution in the presence of external active noise. In simulations, a semiflexible bead-spring chain is considered, in analytical calculations, a continuous linear wormlike chain. Activity is taken into account by independent monomer/site velocities, with orientations changing in a diffusive manner. In simulations, hydrodynamic interactions (HI) are taken into account by the Rotne-Prager-Yamakawa tensor, or by an implementation of the active polymer in the multiparticle collision dynamics approach for fluids. To arrive at an analytical solution, the preaveraged Oseen tensor is employed. The active process implies a dependence of the stationary-state properties on HI via polymer relaxation times. With increasing activity, HI lead to an enhanced swelling of flexible polymers, and the conformational properties differ substantially from those of polymers with self-propelled monomers in presence of HI or free-draining polymers. The polymer mean square displacement is enhanced by HI. Over a wide range of time scales, hydrodynamics leads to a subdiffusive regime of the site mean square displacement for flexible active polymers, with an exponent of (5/7), larger than that of the Rouse (1/2) and Zimm (2/3) models of passive polymers.Comment: 16 pages, 11 figure

Radio astronomy in Africa: the case of Ghana

South Africa has played a leading role in radio astronomy in Africa with the Hartebeesthoek Radio Astronomy Observatory (HartRAO). It continues to make strides with the current seven-dish MeerKAT precursor array (KAT-7), leading to the 64-dish MeerKAT and the giant Square Kilometer Array (SKA), which will be used for transformational radio astronomy research. Ghana, an African partner to the SKA, has been mentored by South Africa over the past six years and will soon emerge in the field of radio astronomy. The country will soon have a science-quality 32m dish converted from a redundant satellite communication antenna. Initially, it will be fitted with 5 GHz and 6.7 GHz receivers to be followed later by a 1.4 - 1.7 GHz receiver. The telescope is being designed for use as a single dish observatory and for participation in the developing African Very Long Baseline Interferometry (VLBI) Network (AVN) and the European VLBI Network. Ghana is earmarked to host a remote station during a possible SKA Phase 2. The location of the country on 5 degree north of the Equator gives it the distinct advantage of viewing the entire plane of the Milky Way galaxy and nearly the whole sky. In this article, we present the case of Ghana in the radio astronomy scene and the science/technology that will soon be carried out by engineers and astronomers.Comment: 6 pages, 3 figures, Full Referred Journal Article accepted for publication in the South African Institute of Physics (SAIP 2014) Conference Proceeding

Permutation Inference for Canonical Correlation Analysis

Canonical correlation analysis (CCA) has become a key tool for population neuroimaging, allowing investigation of associations between many imaging and non-imaging measurements. As other variables are often a source of variability not of direct interest, previous work has used CCA on residuals from a model that removes these effects, then proceeded directly to permutation inference. We show that such a simple permutation test leads to inflated error rates. The reason is that residualisation introduces dependencies among the observations that violate the exchangeability assumption. Even in the absence of nuisance variables, however, a simple permutation test for CCA also leads to excess error rates for all canonical correlations other than the first. The reason is that a simple permutation scheme does not ignore the variability already explained by previous canonical variables. Here we propose solutions for both problems: in the case of nuisance variables, we show that transforming the residuals to a lower dimensional basis where exchangeability holds results in a valid permutation test; for more general cases, with or without nuisance variables, we propose estimating the canonical correlations in a stepwise manner, removing at each iteration the variance already explained, while dealing with different number of variables in both sides. We also discuss how to address the multiplicity of tests, proposing an admissible test that is not conservative, and provide a complete algorithm for permutation inference for CCA.Comment: 49 pages, 2 figures, 10 tables, 3 algorithms, 119 reference

Weak antilocalization in high mobility Ga(x)In(1-x)As/InP two-dimensional electron gases with strong spin-orbit coupling

We have studied the spin-orbit interaction in a high mobility two-dimensional electron gas in a GaInAs/InP heterostructure as a function of an applied gate voltage as well as a function of temperature. Highly sensitive magnetotransport measurements of weak antilocalization as well as measurements of Shubnikov--de Haas oscillations were performed in a wide range of electron sheet concentrations. In our samples the electron transport takes place in the strong spin precession regime in the whole range of applied gate voltages, which is characterized by the spin precession length being shorter than the elastic mean free path. The magnitude of the Rashba spin-orbit coupling parameter was determined by fitting the experimental curves by a simulated quantum conductance correction according to a model proposed recently by Golub [Phys. Rev. B 71, 235310 (2005)]. A comparison of the Rashba coupling parameter extracted using this model with the values estimated from the analysis of the beating pattern in the Shubnikov--de Haas oscillations showed a good agreement.Comment: 5 pages, 5 figures, accepted for publication in Phys.Rev.

Glacial cycles promote greater dispersal, which can help explain larger clutch sizes, in north temperate birds

Earth’s glacial history and patterns in the life history traits of the planet’s avifauna suggest the following interpretations of how recent geological history has affected these key characteristics of the biota: 1) Increased colonizing ability has been an important advantage of increased dispersal, and life history strategies are better categorized by dispersive colonizing ability than by their intrinsic growth rates; 2) Birds of the North Temperate Zone show a greater tendency to disperse, and they disperse farther, than tropical or south temperate birds; 3) Habitat changes associated with glacial advance and retreat selected for high dispersal ability, particularly in the North; and 4) Selection for greater dispersal throughout the unstable Pleistocene has also resulted in other well-recognized life history contrasts, especially larger clutch sizes in birds of North Temperate areas