2,710 research outputs found
Economic incentives and point source emissions : choice of modeling platform
The purpose of this study is to identify the best modeling platform for the analysis of alternative environmental policy instruments designed to reduce the emission of pollutants from point sources, most notably, central power generating stations and manufacturing facilities. The primary analysis of concern is a cost-effectiveness investigation of the policy; where for the most part, the cost of compliance is a multidimensional variable that includes the private costs incurred by the owners of the facility, measures of the change in the cost of providing the facility's product, and estimates of the change in facility capacity factors. The range of pollutants under consideration include the usual menu of air- and waterborne emissions as well as solid and liquid wastes finding their way to landfills and other such disposal options. The range of policies considered include: (a) tariffs on the emission of pollutants; (b) tariffs and subsidies applied to the inputs or the outputs of the point source activities under consideration; (c) limits on the pollutant emissions themselves; and (d) directives regarding the installation of particular equipment and/or the alteration of process activities. The paper also discusses a nonexhaustive set of issues associated with the modeling of point source emissions and policies for their control.Economic Theory&Research,Access to Markets,Markets and Market Access,Consumption,Environmental Economics&Policies
Special Topic: Chesapeake Bay Management -- Welfare Implications of Restricted Triazine Herbicide Use in the Chesapeake Bay Region
The United States Environmental Protection Agency has responsibility under the Federal Insecticide, Fungicide, and Rodenticide Act (FIERA) to formulate pesticide policies on the basis of risk-benefit analyses. To measure the benefits of pesticide use, one must look at the losses in consumer and producer surpluses that would accompany the banning of a particular pesticide. A typical scenario is one in which the banned pesticide is replaced by another that is more costly and/or less effective. The resulting decrease in supply raises the price of the crop on which the banned pesticide is used, and may alter the prices of substitute and complementary crops as well. This article presents a simulation model of com and soybean production in the Chesapeake Bay drainage area to investigate the economic implications of a local ban on triazine herbicides. It reports estimates of lost producer and consumer surplus and the effect that the ban would have on the profitability of agricultural production in the region.Environmental Economics and Policy, Resource /Energy Economics and Policy,
The Origin of Magnetic Interactions in Ca3Co2O6
We investigate the microscopic origin of the ferromagnetic and
antiferromagnetic spin exchange couplings in the quasi one-dimensional cobalt
compound Ca3Co2O6. In particular, we establish a local model which stabilizes a
ferromagnetic alignment of the S=2 spins on the cobalt sites with trigonal
prismatic symmetry, for a sufficiently strong Hund's rule coupling on the
cobalt ions. The exchange is mediated through a S=0 cobalt ion at the
octahedral sites of the chain structure. We present a strong coupling
evaluation of the Heisenberg coupling between the S=2 Co spins on a separate
chain. The chains are coupled antiferromagnetically through super-superexchange
via short O-O bonds.Comment: 5 Pages, 3 Figures; added anisotropy term in eq. 9; extended
discussion of phase transitio
Morphology and density of post-CME current sheets
Eruption of a coronal mass ejection (CME) drags and "opens" the coronal
magnetic field, presumably leading to the formation of a large-scale current
sheet and the field relaxation by magnetic reconnection. We analyze physical
characteristics of ray-like coronal features formed in the aftermath of CMEs,
to check if the interpretation of this phenomenon in terms of reconnecting
current sheet is consistent with the observations. The study is focused on
measurements of the ray width, density excess, and coronal velocity field as a
function of the radial distance. The morphology of rays indicates that they
occur as a consequence of Petschek-like reconnection in the large scale current
sheet formed in the wake of CME. The hypothesis is supported by the flow
pattern, often showing outflows along the ray, and sometimes also inflows into
the ray. The inferred inflow velocities range from 3 to 30 km s,
consistent with the narrow opening-angle of rays, adding up to a few degrees.
The density of rays is an order of magnitude larger than in the ambient corona.
The density-excess measurements are compared with the results of the analytical
model in which the Petschek-like reconnection geometry is applied to the
vertical current sheet, taking into account the decrease of the external
coronal density and magnetic field with height. The model results are
consistent with the observations, revealing that the main cause of the density
excess in rays is a transport of the dense plasma from lower to larger heights
by the reconnection outflow
On Solving the Coronal Heating Problem
This article assesses the current state of understanding of coronal heating,
outlines the key elements of a comprehensive strategy for solving the problem,
and warns of obstacles that must be overcome along the way.Comment: Accepted by Solar Physics; Published by Solar Physic
Dynamics of Ganymede's magnetopause: Intermittent reconnection under steady external conditions
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95138/1/jgra20818.pd
Plasmoids in Reconnecting Current Sheets: Solar and Terrestrial Contexts Compared
Magnetic reconnection plays a crucial role in violent energy conversion
occurring in the environments of high electrical conductivity, such as the
solar atmosphere, magnetosphere, and fusion devices. We focus on the
morphological features of the process in two different environments, the solar
atmosphere and the geomagnetic tail. In addition to indirect evidence that
indicates reconnection in progress or having just taken place, such as auroral
manifestations in the magnetosphere and the flare loop system in the solar
atmosphere, more direct evidence of reconnection in the solar and terrestrial
environments is being collected. Such evidence includes the reconnection inflow
near the reconnecting current sheet, and the outflow along the sheet
characterized by a sequence of plasmoids. Both turbulent and unsteady
Petschek-type reconnection processes could account for the observations. We
also discuss other relevant observational consequences of both mechanisms in
these two settings. While on face value, these are two completely different
physical environments, there emerge many commonalities, for example, an Alfven
speed of the same order of magnitude, a key parameter determining the
reconnection rate. This comparative study is meant as a contribution to current
efforts aimed at isolating similarities in processes occurring in very
different contexts in the heliosphere, and even in the universe.Comment: 21 pages, 9 figures, in press at J. Geophys. Res. (Space Physics),
for the special NESSC section on Comparative Aspects of Magnetic Reconnectio
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS
The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured
Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector
The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30
- …