658 research outputs found
National Environmental Policy During the Clinton Years
We review major developments in national environmental policy during the Clinton Administration, defining environmental policy to include not only the statutes, regulations, and policies associated with reducing pollution, but also major issues of public lands management and species preservation. We adopt economic criteria for policy assessment and highlight a set of five themes that emerge in the economics of national environmental policy over the past decade. First, over the course of the decade, national environmental targets were made more stringent, and environmental quality improved. Most important among the new targets were the National Ambient Air Quality Standards (NAAQS) for ambient ozone and particulate matter, issued by EPA in July 1997, which could turn out to be one of the Clinton Administration's most enduring environmental legacies. Also, natural resource policy during the Clinton years was heavily weighted toward environmental protection. Environmental quality improved overall during the decade, continuing a trend that began in the 1970s, although improvements were much less than during the previous two decades. Second, the use of benefit-cost analysis for assessing environmental regulation was controversial in the Clinton Administration, while economic efficiency emerged as a central goal of the regulatory reform movement in the Congress during the 1990s. When attention was given to increased efficiency, the locus of that attention during the Clinton years was the Congress in the case of environmental policies and the Administration in the case of natural resource policies. Ironically, the increased attention given to benefit-cost analysis may not have had a marked effect on the economic efficiency of environmental regulations. Third, cost-effectiveness achieved a much more prominent position in public discourse regarding environmental policy during the 1990s. From the Bush Administration through the Clinton Administration, interest and activity regarding market-based instruments for environmental protection, particularly tradeable permit systems, continued to increase. Fourth, the Clinton Administration put much greater emphasis than previous administrations on expanding the role of environmental information disclosure and voluntary programs. While such programs can provide cost-effective ways of reaching environmental policy goals, little is known about their actual costs or effectiveness. Fifth and finally, the Environmental Protection Agency placed much less emphasis on economic analysis during the 1990s. EPA leadership was more hostile to economic analysis than it had been under the prior Bush Administration, and it made organizational changes to reflect this change in priorities.
Do Consumers React to the Shape of Supply? Water Demand Under Heterogeneous Price Structures
Urban water pricing provides an opportunity to examine whether consumers react to the shape of supply functions. We carry out an empirical analysis of the influence of price and price structure on residential water demand, using the most price-diverse, detailed, household-level water demand data yet available for this purpose. We adapt the Hausman model of labor supply under progressive income taxation to estimate water demand under non-linear prices. Ours is the first analysis to address both the simultaneous determination of marginal price and water demand under block pricing and the possibility of endogenous price structures in the cross section. In order to examine the possibility that consumers facing block prices are more price-responsive, all else equal, we test for price elasticity differences across price structures. We find that households facing block prices are more sensitive to price increases than households facing uniform marginal prices. Tests for endogenous price structures cannot rule out a behavioral response to the shape of supply, but suggest that observed differences in price elasticity under supply curves of varying shapes may result, in part, from underlying heterogeneity among utility service areas.
Multi-State Trials of Bt Sweet Corn Varieties for Control of the Corn Earworm (Lepidoptera: Noctuidae)
Field tests in 2010-2011 were performed in New York, Minnesota, Maryland, Ohio, and Georgia to compare Bt sweet corn lines expressing Cry1A.105 + Cry2Ab2 and Cry1Ab with their non-Bt isolines, with and without the use of foliar insecticides. The primary insect pest in all locations during the trial years was Heliocoverpa zea (Boddie), which is becoming the most serious insect pest of sweet corn in the United States. At harvest, the ears were measured for marketability according to fresh market and processing standards. For fresh market and processing, least squares regression showed significant effects of protein expression, state, and insecticide frequency. There was a significant effect of year for fresh market but not for processing. The model also showed significant effects of H. zea per ear by protein expression. Sweet corn containing two genes (Cry1A.105 + Cry2Ab2) and a single gene (Cry1Ab) provided high marketability, and both Bt varieties significantly outperformed the traditional non-Bt isolines in nearly all cases regardless of insecticide application frequency. For pest suppression of H. zea, plants expressing Bt proteins consistently performed better than non-Bt isoline plants, even those sprayed at conventional insecticide frequencies. Where comparisons in the same state were made between Cry1A.105 + Cry2Ab2 and Cry1Ab plants for fresh market, the product expressing Cry1A.105 + Cry2Ab2 provided better protection and resulted in less variability in control. Overall, these results indicate Cry1A.105 + Cry2Ab2 and Cry1Ab plants are suitable for fresh market and processing corn production across a diversity of growing regions and years. Our results demonstrate that Bt sweet corn has the potential to significantly reduce the use of conventional insecticides against lepidopteran pests and, in turn, reduce occupational and environmental risks that arise from intensive insecticide us
Extending the applicability of the dose addition model to the assessment of chemical mixtures of partial agonists by using a novel toxic unit extrapolation method
This article has been made available through the Brunel Open Access Publishing Fund.Dose addition, a commonly used concept in toxicology for the prediction of chemical mixture effects, cannot readily be applied to mixtures of partial agonists with differing maximal effects. Due to its mathematical features, effect levels that exceed the maximal effect of the least efficacious compound present in the mixture, cannot be calculated. This poses problems when dealing with mixtures likely to be encountered in realistic assessment situations where chemicals often show differing maximal effects. To overcome this limitation, we developed a pragmatic solution that extrapolates the toxic units of partial agonists to effect levels beyond their maximal efficacy. We extrapolated different additivity expectations that reflect theoretically possible extremes and validated this approach with a mixture of 21 estrogenic chemicals in the E-Screen. This assay measures the proliferation of human epithelial breast cancers. We found that the dose-response curves of the estrogenic agents exhibited widely varying shapes, slopes and maximal effects, which made it necessary to extrapolate mixture responses above 14% proliferation. Our toxic unit extrapolation approach predicted all mixture responses accurately. It extends the applicability of dose addition to combinations of agents with differing saturating effects and removes an important bottleneck that has severely hampered the use of dose addition in the past. © 2014 Scholze et al
Global attractors for strongly damped wave equations with displacement dependent damping and nonlinear source term of critical exponent
In this paper the long time behaviour of the solutions of 3-D strongly damped
wave equation is studied. It is shown that the semigroup generated by this
equation possesses a global attractor in H_{0}^{1}(\Omega)\times L_{2}(\Omega)
and then it is proved that this global attractor is a bounded subset of
H^{2}(\Omega)\times H^{2}(\Omega) and also a global attractor in
H^{2}(\Omega)\cap H_{0}^{1}(\Omega)\times H_{0}^{1}(\Omega)
Shape Transition in the Epitaxial Growth of Gold Silicide in Au Thin Films on Si(111)
Growth of epitaxial gold silicide islands on bromine-passivated Si(111)
substrates has been studied by optical and electron microscopy, electron probe
micro analysis and helium ion backscattering. The islands grow in the shape of
equilateral triangles up to a critical size beyond which the symmetry of the
structure is broken, resulting in a shape transition from triangle to
trapezoid. The island edges are aligned along directions. We have
observed elongated islands with aspect ratios as large as 8:1. These islands,
instead of growing along three equivalent [110] directions on the Si(111)
substrate, grow only along one preferential direction. This has been attributed
to the vicinality of the substrate surface.Comment: revtex version 3.0, 11 pages 4 figures available on request from
[email protected] - IP/BBSR/93-6
Disk-Jet Connection in the Radio Galaxy 3C 120
We present the results of extensive multi-frequency monitoring of the radio
galaxy 3C 120 between 2002 and 2007 at X-ray, optical, and radio wave bands, as
well as imaging with the Very Long Baseline Array (VLBA). Over the 5 yr of
observation, significant dips in the X-ray light curve are followed by
ejections of bright superluminal knots in the VLBA images. Consistent with
this, the X-ray flux and 37 GHz flux are anti-correlated with X-ray leading the
radio variations. This implies that, in this radio galaxy, the radiative state
of accretion disk plus corona system, where the X-rays are produced, has a
direct effect on the events in the jet, where the radio emission originates.
The X-ray power spectral density of 3C 120 shows a break, with steeper slope at
shorter timescale and the break timescale is commensurate with the mass of the
central black hole based on observations of Seyfert galaxies and black hole
X-ray binaries. These findings provide support for the paradigm that black hole
X-ray binaries and active galactic nuclei are fundamentally similar systems,
with characteristic time and size scales linearly proportional to the mass of
the central black hole. The X-ray and optical variations are strongly
correlated in 3C 120, which implies that the optical emission in this object
arises from the same general region as the X-rays, i.e., in the accretion
disk-corona system. We numerically model multi-wavelength light curves of 3C
120 from such a system with the optical-UV emission produced in the disk and
the X-rays generated by scattering of thermal photons by hot electrons in the
corona. From the comparison of the temporal properties of the model light
curves to that of the observed variability, we constrain the physical size of
the corona and the distances of the emitting regions from the central BH.Comment: Accepted for publication in the Astrophysical Journal. 28 pages, 21
figures, 2 table
The Baryon Oscillation Spectroscopic Survey of SDSS-III
The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the
scale of baryon acoustic oscillations (BAO) in the clustering of matter over a
larger volume than the combined efforts of all previous spectroscopic surveys
of large scale structure. BOSS uses 1.5 million luminous galaxies as faint as
i=19.9 over 10,000 square degrees to measure BAO to redshifts z<0.7.
Observations of neutral hydrogen in the Lyman alpha forest in more than 150,000
quasar spectra (g<22) will constrain BAO over the redshift range 2.15<z<3.5.
Early results from BOSS include the first detection of the large-scale
three-dimensional clustering of the Lyman alpha forest and a strong detection
from the Data Release 9 data set of the BAO in the clustering of massive
galaxies at an effective redshift z = 0.57. We project that BOSS will yield
measurements of the angular diameter distance D_A to an accuracy of 1.0% at
redshifts z=0.3 and z=0.57 and measurements of H(z) to 1.8% and 1.7% at the
same redshifts. Forecasts for Lyman alpha forest constraints predict a
measurement of an overall dilation factor that scales the highly degenerate
D_A(z) and H^{-1}(z) parameters to an accuracy of 1.9% at z~2.5 when the survey
is complete. Here, we provide an overview of the selection of spectroscopic
targets, planning of observations, and analysis of data and data quality of
BOSS.Comment: 49 pages, 16 figures, accepted by A
The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey
The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic
data from the Baryon Oscillation Spectroscopic Survey (BOSS). This ninth data
release (DR9) of the SDSS project includes 535,995 new galaxy spectra (median
z=0.52), 102,100 new quasar spectra (median z=2.32), and 90,897 new stellar
spectra, along with the data presented in previous data releases. These spectra
were obtained with the new BOSS spectrograph and were taken between 2009
December and 2011 July. In addition, the stellar parameters pipeline, which
determines radial velocities, surface temperatures, surface gravities, and
metallicities of stars, has been updated and refined with improvements in
temperature estimates for stars with T_eff<5000 K and in metallicity estimates
for stars with [Fe/H]>-0.5. DR9 includes new stellar parameters for all stars
presented in DR8, including stars from SDSS-I and II, as well as those observed
as part of the SDSS-III Sloan Extension for Galactic Understanding and
Exploration-2 (SEGUE-2).
The astrometry error introduced in the DR8 imaging catalogs has been
corrected in the DR9 data products. The next data release for SDSS-III will be
in Summer 2013, which will present the first data from the Apache Point
Observatory Galactic Evolution Experiment (APOGEE) along with another year of
data from BOSS, followed by the final SDSS-III data release in December 2014.Comment: 9 figures; 2 tables. Submitted to ApJS. DR9 is available at
http://www.sdss3.org/dr
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