2,102 research outputs found
Environmental taxes and policies for developing countries
Increasing urbanization and industrialization can exacerbate pollution problems in developing countries. Tax revenues in developing countries are too low to support adequate infrastructure for treating and disposing of wastes, but the problem is also attributable to the classic problem of externalities in productiion and consumption."Externalities"means that the costs of environmental degradation are not considered by the private decisionmakers undertaking the activities that cause the problems. Two types of policies are commonly considered to correct this market failure and improve the allocation of resources: command-and-control policies (such as emmission and abatement standards) and market-based incentive policies (such as emissions charges, taxes on production and consumption, and marketable pollution quotas), which raise the price of such activities for the perpetrators. Market based incentives theoretically reduce pollution at least cost and increase government revenues, but may require costly monitoring to be effective, and are usually implemented in an environment of imperfect information about the costs of abatement. Sometimes command and control policies make more economic sense in this environment. Efficiency gains from curbing pollution in developing countries may be large. Some polluting activities are subsidized, so curtailing them brings both fiscal and environmental benefits. Taxing polluting inputs and outputs is a particularly attractive policy in developing countries which often lack experience in administering and enforcing other types of environmental regulation. Corrective taxes make use of existing administrative structures and increase tax revenues, which can be spent on public goods to improve environmental quality (including treatment facilities for water and sewage, waste disposal, and sanitation) or can be used to reduce other taxes (which are often highly distortionary in countries with a narrow tax base). Which goods and inputs to single out for corrective taxation depends on the main sources of pollution, which varies from country to country. Air pollution from vehicles is growing in many countries where increased fuel taxes, perhaps coupled with improved regulations for vehicle maintenance, may be desirable. Higher taxes on high sulphur coal would curb both industiral and household emissions of sulphur dioxide. Charges can be implemented for fixed site easy to monitor industrial emissions. Subsidies to industries that cause pollution should be phased out and those industries should be subjected to higher than average tax rates.Water and Industry,Economic Theory&Research,Urban Services to the Poor,Urban Services to the Poor,Environmental Economics&Policies
Optimal jet radius in kinematic dijet reconstruction
Obtaining a good momentum reconstruction of a jet is a compromise between
taking it large enough to catch the perturbative final-state radiation and
small enough to avoid too much contamination from the underlying event and
initial-state radiation. In this paper, we compute analytically the optimal jet
radius for dijet reconstructions and study its scale dependence. We also
compare our results with previous Monte-Carlo studies.Comment: 30 pages, 11 figures; minor corrections; published in JHE
The genome sequence and effector complement of the flax rust pathogen Melampsora lini
Rust fungi cause serious yield reductions on crops, including wheat, barley, soybean, coffee, and represent real threats to global food security. Of these fungi, the flax rust pathogen Melampsora lini has been developed most extensively over the past 80 years as a model to understand the molecular mechanisms that underpin pathogenesis. During infection, M. lini secretes virulence effectors to promote disease. The number of these effectors, their function and their degree of conservation across rust fungal species is unknown. To assess this, we sequenced and assembled de novo the genome of M. lini isolate CH5 into 21,130 scaffolds spanning 189 Mbp (scaffold N50 of 31 kbp). Global analysis of the DNA sequence revealed that repetitive elements, primarily retrotransposons, make up at least 45% of the genome. Using ab initio predictions, transcriptome data and homology searches, we identified 16,271 putative protein-coding genes. An analysis pipeline was then implemented to predict the effector complement of M. lini and compare it to that of the poplar rust, wheat stem rust and wheat stripe rust pathogens to identify conserved and species-specific effector candidates. Previous knowledge of four cloned M. lini avirulence effector proteins and two basidiomycete effectors was used to optimize parameters of the effector prediction pipeline. Markov clustering based on sequence similarity was performed to group effector candidates from all four rust pathogens. Clusters containing at least one member from M. lini were further analyzed and prioritized based on features including expression in isolated haustoria and infected leaf tissue and conservation across rust species. Herein, we describe 200 of 940 clusters that ranked highest on our priority list, representing 725 flax rust candidate effectors. Our findings on this important model rust species provide insight into how effectors of rust fungi are conserved across species and how they may act to promote infection on their hosts.This work
was funded by a grant from the CSIRO Transformational Biology
Capability Platform to Adnane Nemri. Claire Anderson was supported
by an ARC Discovery Grant (DP120104044) awarded to
David A. Jones and Peter N. Dodds
FastJet user manual
FastJet is a C++ package that provides a broad range of jet finding and
analysis tools. It includes efficient native implementations of all widely used
2-to-1 sequential recombination jet algorithms for pp and e+e- collisions, as
well as access to 3rd party jet algorithms through a plugin mechanism,
including all currently used cone algorithms. FastJet also provides means to
facilitate the manipulation of jet substructure, including some common boosted
heavy-object taggers, as well as tools for estimation of pileup and
underlying-event noise levels, determination of jet areas and subtraction or
suppression of noise in jets.Comment: 69 pages. FastJet 3 is available from http://fastjet.fr
Role of Sequence and Structure of the Hendra Fusion Protein Fusion Peptide in Membrane Fusion
Viral fusion proteins are intriguing molecular machines that undergo drastic conformational changes to facilitate virus-cell membrane fusion. During fusion a hydrophobic region of the protein, termed the fusion peptide (FP), is inserted into the target host cell membrane, with subsequent conformational changes culminating in membrane merger. Class I fusion proteins contain FPs between 20 and 30 amino acids in length that are highly conserved within viral families but not between. To examine the sequence dependence of the Hendra virus (HeV) fusion (F) protein FP, the first eight amino acids were mutated first as double, then single, alanine mutants. Mutation of highly conserved glycine residues resulted in inefficient F protein expression and processing, whereas substitution of valine residues resulted in hypofusogenic F proteins despite wild-type surface expression levels. Synthetic peptides corresponding to a portion of the HeV F FP were shown to adopt an α-helical secondary structure in dodecylphosphocholine micelles and small unilamellar vesicles using circular dichroism spectroscopy. Interestingly, peptides containing point mutations that promote lower levels of cell-cell fusion within the context of the whole F protein were less α-helical and induced less membrane disorder in model membranes. These data represent the first extensive structure-function relationship of any paramyxovirus FP and demonstrate that the HeV F FP and potentially other paramyxovirus FPs likely require an α-helical structure for efficient membrane disordering and fusion
Cosmic optical activity in the spacetime of a scalar-tensor screwed cosmic string
Measurements of radio emission from distant galaxies and quasars verify that
the polarization vectors of these radiations are not randomly oriented as
naturally expected. This peculiar phenomenon suggests that the spacetime
intervening between the source and observer may be exhibiting some sort of
optical activity, the origin of which is not known. In the present paper we
provide a plausible explanation to this phenomenon by investigating the r\^ole
played by a Chern-Simons-like term in the background of an ordinary or
superconducting screwed cosmic string in a scalar-tensor gravity. We discuss
the possibility that the excess in polarization of the light from
radio-galaxies and quasars can be understood as if the electromagnetic waves
emitted by these cosmic objects interact with a scalar-tensor screwed cosmic
string through a Chern-Simons coupling. We use current astronomical data to
constrain possible values for the coupling constant of this theory, and show
that it turns out to be: eV, which is two orders of
magnitude larger than in string-inspired theories.Comment: Revised version, to appear in Phys. Rev.
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