347 research outputs found
EFFICIENCY MEASURES USING THE RAY-HOMOTHETIC FUNCTION: A MULTIPERIOD ANALYSIS
Recent investigations have provided mixed assessments of farm firm efficiency. This analysis examined the efficiency of a homogeneous sample of central Illinois grain farms over a six-year period. A best-practice frontier was constructed using the ray-homothetic function, which allowed optimal farm output to vary with factor intensity. Efficiency measures were found to increase with temporal aggregation. The ray-homothetic approach was found to attribute high scale inefficiencies to larger sample farms in cases where the factor shares did not vary appreciably across farms. The findings suggest that policy recommendations regarding farm efficiency must be made with care.Agribusiness,
Wind-tunnel studies of certain meteorological tower siting characteristics at the James A. FitzPatrick Nuclear Power Station
Final report (November 1986-January 1988).CER87-88-RNM-RLE-SHS-DEN1.February 1988.CSU contract (i.e. project) no. 2-96920.Includes bibliographical references (pages 50-51).For New York Power Authority, Contract no. 027277-86
Constellation array in scorpion genera \u3cem\u3eParuroctonus\u3c/em\u3e, \u3cem\u3eSmeringurus\u3c/em\u3e, \u3cem\u3eVejovoidus\u3c/em\u3e, and \u3cem\u3eParavaejovis\u3c/em\u3e (Scorpiones: Vaejovidae)
The constellation array (a recently discovered sensory structure on the fixed finger of pedipalp; Fet et al., 2006) is analyzed for a large set of species belonging to four genera in the family Vaejovidae: Paruroctonus, Smeringurus, Vejovoidus, and Paravaejovis. It is shown that this structure is an important taxonomic character. Two distinct configurations are identified, a two-sensilla array for Paruroctonus + Smeringurus + Vejovoidus and a three-sensilla array for genus Paravejovis, both differing from other vaejovid configurations so far investigated. The topology of these two array configurations are analyzed using landmark setae identified in this study
Renewable energy in fisheries and aquaculture: Case studies from the United States
Fisheries and aquaculture are highly reliant on fossil fuels and must transition to renewable energy to reduce carbon emissions and meet global planetary heath goals. Here, we assessed total and renewable energy use in farmed catfish and wild-caught salmon, two of the largest seafood sectors in the United States (U.S.). Interviews were used to explore participants’ views of key barriers and opportunities to replace fossil fuel use. Modeled scenarios were used to assess changes in grid source energy and electricity costs for the farmed catfish sector using the U.S. EIA National Energy Modeling System. We found that renewable energy makes up 5% of direct energy use in catfish aquaculture in Mississippi and Alabama. Catfish industry interviewees indicate that cheap electricity costs and diurnal energy use are barriers to onsite implementation of renewables. Projected renewable energy use for the catfish sector could be as high as 41% of total direct energy use in 2050 under modeled scenarios, which would result in 86% lower CO2 emissions but 34% higher electricity costs. For wild-capture pink salmon from Prince William Sound, Alaska (AK) and sockeye salmon from Bristol Bay, AK, renewable energy makes up 2% and 0% of direct energy use, respectively. Wild-caught salmon industry interviewees identified the short duration of the fishing season as a barrier for onsite renewable energy, though there is a desire for more regional renewable energy technologies to lower electricity costs and increase reliability. Proposed renewable energy projects at utilities in fish processing towns in AK would only make modest improvements in the share of direct energy from renewables due to fuel use by fishing vessels. This is the first study to characterize current and potential renewable energy use among parts of the fisheries and aquaculture sectors in the U.S. We found that energy needs for fisheries and aquaculture are influenced by their often-remote location, production methods, and seasonal energy demands, which require context-specific solutions. There is the need for federal and state policies and incentives to shift energy sources used in these sectors to meet national and international climate change goals while supporting food security.publishedVersio
Minkowski's Object: A Starburst Triggered by a Radio Jet, Revisited
We present neutral hydrogen, ultraviolet, optical and near-infrared imaging,
and optical spectroscopy, of Minkowski's Object (MO), a star forming peculiar
galaxy near NGC 541. The observations strengthen evidence that star formation
in MO was triggered by the radio jet from NGC 541. Key new results are the
discovery of a 4.9E8 solar mass double HI cloud straddling the radio jet
downstream from MO, where the jet changes direction and decollimates; strong
detections of MO, also showing double structure, in UV and H-alpha; and
numerous HII regions and associated clusters in MO. In UV, MO resembles the
radio-aligned, rest-frame UV morphologies in many high redshift radio galaxies
(HzRGs), also thought to be caused by jet-induced star formation. MO's stellar
population is dominated by a 7.5 Myr-old, 1.9E7 solar mass instantaneous burst,
with current star formation rate 0.52 solar masses per year (concentrated
upstream from where the HI column density is high). This is unlike the
jet-induced star formation in Centaurus A, where the jet interacts with
pre-existing cold gas; in MO the HI may have cooled out of a warmer, clumpy
intergalactic or interstellar medium as a result of jet interaction, followed
by collapse of the cooling clouds and subsequent star formation (consistent
with numerical simulations). Since the radio source that triggered star
formation in MO is much less luminous, and therefore more common, than powerful
HzRGs, and because the environment around MO is not particularly special in
terms of abundant dense, cold gas, jet-induced star formation in the early
universe might be even more prevalent than previously thought.Comment: 52 pages, 15 figures, accepted for publication in Ap
Recent star formation in nearby galaxies from GALEX imaging:M101 and M51
The GALEX (Galaxy Evolution Explorer) Nearby Galaxies Survey is providing
deep far-UV and near-UV imaging for a representative sample of galaxies in the
local universe. We present early results for M51 and M101, from GALEX UV
imaging and SDSS optical data in five bands. The multi-band photometry of
compact stellar complexes in M101 is compared to population synthesis models,
to derive ages, reddening, reddening-corrected luminosities and current/initial
masses. The GALEX UV photometry provides a complete census of young compact
complexes on a approximately 160pc scale. A galactocentric gradient of the
far-UV - near-UV color indicates younger stellar populations towards the outer
parts of the galaxy disks, the effect being more pronounced in M101 than in
M51.Comment: This paper will be published as part of the Galaxy Evolution Explorer
(GALEX) Astrophysical Journal Letters Special Issue. Full paper available
from http://dolomiti.pha.jhu.edu . Links to full set of papers will be
available at http://www.galex.caltech.edu/PUBLICATIONS/ after November 22,
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Range corrections for two-neutron halo nuclei in effective theory
The range corrections to the universal properties and structure of
two-neutron halo nuclei are investigated within an effective quantum mechanics
framework. Treating the nucleus as an effective three-body system, we make a
systematic improvement upon previous calculations by calculating the linear
range corrections at next-to-leading order. Since the effective ranges for the
neutron-core interactions are not known, we estimate the effective range to be
set by the inverse of the pion mass. We investigate the possibility of excited
Efimov states in two-neutron halo nuclei and calculate their mean square radii
to next-to-leading order. We find that the effective range corrections are
generally small and the leading order predictions are very robust.Comment: 19 pages, 4 eps figures, revtex4, final version to appear in Nucl.
Phys.
Ancillary health effects of climate mitigation scenarios as drivers of policy uptake: a review of air quality, transportation and diet co-benefits modeling studies
Background: Significant mitigation efforts beyond the Nationally Determined Commitments (NDCs) coming out of the 2015 Paris Climate Agreement are required to avoid warming of 2 °C above pre-industrial temperatures. Health co-benefits represent selected near term, positive consequences of climate policies that can offset mitigation costs in the short term before the beneficial impacts of those policies on the magnitude of climate change are evident. The diversity of approaches to modeling mitigation options and their health effects inhibits meta-analyses and syntheses of results useful in policy-making. Methods/Design: We evaluated the range of methods and choices in modeling health co-benefits of climate mitigation to identify opportunities for increased consistency and collaboration that could better inform policy-making. We reviewed studies quantifying the health co-benefits of climate change mitigation related to air quality, transportation, and diet published since the 2009 Lancet Commission 'Managing the health effects of climate change' through January 2017. We documented approaches, methods, scenarios, health-related exposures, and health outcomes. Results/Synthesis: Forty-two studies met the inclusion criteria. Air quality, transportation, and diet scenarios ranged from specific policy proposals to hypothetical scenarios, and from global recommendations to stakeholder-informed local guidance. Geographic and temporal scope as well as validity of scenarios determined policy relevance. More recent studies tended to use more sophisticated methods to address complexity in the relevant policy system. Discussion: Most studies indicated significant, nearer term, local ancillary health benefits providing impetus for policy uptake and net cost savings. However, studies were more suited to describing the interaction of climate policy and health and the magnitude of potential outcomes than to providing specific accurate estimates of health co-benefits. Modeling the health co-benefits of climate policy provides policy-relevant information when the scenarios are reasonable, relevant, and thorough, and the model adequately addresses complexity. Greater consistency in selected modeling choices across the health co-benefits of climate mitigation research would facilitate evaluation of mitigation options particularly as they apply to the NDCs and promote policy uptake
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