1,245 research outputs found

    CONTROL OF NONPOINT SOURCE POLLUTION THROUGH VOLUNTARY INCENTIVE-BASED POLICIES: AN APPLICATION TO NITRATE CONTAMINATION IN NEW YORK

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    A voluntary program is developed to achieve environmental goals through the self-interested choices of farmers under environmental risk and asymmetric information. Farmers behave to maximize expected net returns, and environmental quality standards are formulated through chance constraints. Because the government may not know each farmer's soil type, policy options must be self-selecting. The model is applied empirically to nitrate leaching and runoff from corn production in three New York regions. Asymmetric information between producers and the government would impose additional cost burdens on society, but these costs are modest in the context of other farm programs.Environmental Economics and Policy,

    OPTIMAL LAND CONVERSION AT THE RURAL-URBAN FRINGE WITH POSITIVE AND NEGATIVE AGRICULTURAL EXTERNALITIES

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    Bid-rent curves are incorporated in a stochastic dynamic programming model of land development around a city when farmland generates both positive and negative externalities. The model delineates how the quantities of land in various uses over time should depend on the relative social weights assigned to the competing agricultural externalities.Land Economics/Use,

    Frequency and Risk Factors for the Occurrence of Work Related Musculoskeletal Disorders among Slaughter House Workers in Nairobi County

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    Work-related musculoskeletal disorders describe a wide range of inflammatory and degenerative disorders and diseases such as metacarpal syndrome, tenosynovitis, tendonitis, fasciitis, epicondilytis, shoulder impingement syndrome among others, resulting in pain and functional impairment. The main objective of this study was to determine the frequency and risk factors for the occurrence of work related muscular disorders among slaughter house workers in Nairobi County. The study adopted a cross sectional descriptive design. Cluster sampling was used to select a sample of 155 workers from the selected slaughter houses within Nairobi County. Oral interviews, questionnaires and observational methods were used to collect both qualitative and quantitative which was analysed using SPSS version 20. Data was analysed using chi square test for association. The study results showed that majority of the workers (82.4% n=128) experienced pain in one or more parts of the body. Frequency of neck pain stood at 15% (19), wrist and hand pain at 29.6% (38), shoulder pain at 51% (65), hips and thigh pain at 2% (3). Risk factors were identified as lack of breaks during working hours, working for long hours, working posture and change of duty after sick off. There is a high prevalence of work related musculoskeletal pain associated with development of musculoskeletal disorders among slaughter house workers in Nairobi County. The slaughter houses management should restrict the number of working hours to 8 hours in any working day. Key words: Risk Factors, Occurrence, prevalence, Nairobi County, pain, slaughter house, MSD

    Acceleration management: the semiconductor industry confronts the 21st century

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    In the recent generations of semiconductor devices, the semiconductor industry has been accelerating towards the limits of the physical sciences. As a consequence, technology managers in that industry face seven major challenges, which will threaten progress: process, complexity, performance, power, density, productivity, and quality / reliability. We believe that confronting these challenges requires a new approach to technology management both within organizations and between organizations that form the backbone of the industry. We call this new approach Acceleration Management. Acceleration Management first requires that firms cultivate deep technical knowledge and inspire creative solutions to seemingly insoluble technical problems. The second stage of Acceleration Management requires the necessary expertise to be pooled, which often demands inter-organizational cooperation. This paper explores these managerial imperatives and analyzes how new semiconductor firms--particularly in China--have created niches in the value chain even during a tumultuous time in the industry\u27s history

    Nearshore mixing and nutrient delivery along the western Antarctic Peninsula

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    The surface waters of the Southern Ocean play a key role in the global climate and carbon cycles by promoting growth of some of the world’s largest phytoplankton blooms. Several studies have emphasized the importance of glacial and sediment inputs of Fe that fuel the primary production of the Fe-limited Southern Ocean. Although the fertile surface waters along the shelf of the western Antarctic Peninsula (WAP) are influenced by large inputs of freshwater, this freshwater may take multiple pathways (e.g. calving, streams, groundwater discharge) with different degrees of water-rock interactions leading to variable Fe flux to coastal waters. During the summers of 2012–13 and 2013–14, seawater samples were collected along the WAP, near Anvers Island, to observe water column dynamics in nearshore and offshore waters. Tracers (223,224Ra, 222Rn, 18O, 2H) were used to evaluate the source and transport of water and nutrients in coastal fjords and across the shelf. Coastal waters are compared across two field seasons, with increased freshwater observed during 2014. Horizontal mixing rates of water masses along the WAP ranged from 110–3600 m2 s-1. These mixing rates suggest a rapid transport mechanism for moving meltwater offshore.ECU Open Access Publishing Support Fun

    Carbon Dioxide-Induced Oscillations in Fluorescence and Photosynthesis

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    A Guide for Using NIH Image J for Single Slice Cross-Sectional Area and Composition Analysis of the Thigh from Computed Tomography

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    Reports using computed tomography (CT) to estimate thigh skeletal muscle cross-sectional area and mean muscle attenuation are often difficult to evaluate due to inconsistent methods of quantification and/or poorly described analysis methods. This CT tutorial provides step-by-step instructions in using free, NIH Image J software to quantify both muscle size and composition in the mid-thigh, which was validated against a robust commercially available software, SliceOmatic. CT scans of the mid-thigh were analyzed from 101 healthy individuals aged 65 and older. Mean cross-sectional area and mean attenuation values are presented across seven defined Hounsfield unit (HU) ranges along with the percent contribution of each region to the total mid-thigh area. Inter-software correlation coefficients ranged from R2 = 0.92–0.99 for all specific area comparisons measured using the Image J method compared to SliceOmatic. We recommend reporting individual HU ranges for all areas measured. Although HU range 0–100 includes the majority of skeletal muscle area, HU range -29 to 150 appears to be the most inclusive for quantifying total thigh muscle. Reporting all HU ranges is necessary to determine the relative contribution of each, as they may be differentially affected by age, obesity, disease, and exercise. This standardized operating procedure will facilitate consistency among investigators reporting computed tomography characteristics of the thigh on single slice images. Trial Registration: ClinicalTrials.gov NCT02308228

    The Black Hole Mass of NGC 4151: Comparison of Reverberation Mapping and Stellar Dynamical Measurements

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    We present a stellar dynamical estimate of the black hole (BH) mass in the Seyfert 1 galaxy, NGC 4151. We analyze ground-based spectroscopy as well as imaging data from the ground and space, and we construct 3-integral axisymmetric models in order to constrain the BH mass and mass-to-light ratio. The dynamical models depend on the assumed inclination of the kinematic symmetry axis of the stellar bulge. In the case where the bulge is assumed to be viewed edge-on, the kinematical data give only an upper limit to the mass of the BH of ~4e7 M_sun (1 sigma). If the bulge kinematic axis is assumed to have the same inclination as the symmetry axis of the large-scale galaxy disk (i.e., 23 degrees relative to the line of sight), a best-fit dynamical mass between 4-5e7 M_sun is obtained. However, because of the poor quality of the fit when the bulge is assumed to be inclined (as determined by the noisiness of the chi^2 surface and its minimum value), and because we lack spectroscopic data that clearly resolves the BH sphere of influence, we consider our measurements to be tentative estimates of the dynamical BH mass. With this preliminary result, NGC 4151 is now among the small sample of galaxies in which the BH mass has been constrained from two independent techniques, and the mass values we find for both bulge inclinations are in reasonable agreement with the recent estimate from reverberation mapping (4.57[+0.57/-0.47]e7 M_sun) published by Bentz et al.Comment: 20 pages, including 11 low-res figures. Accepted for publication in ApJ. High resolution version available upon reques

    The Ionized Gas and Nuclear Environment in NGC 3783. I. Time-Averaged 900 ks Chandra Grating Spectroscopy

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    We present results from a 900 ks exposure of NGC 3783 with the High-Energy Transmission Grating Spectrometer on board the Chandra X-ray Observatory. The resulting X-ray spectrum has the best combination of signal-to-noise and resolution ever obtained for an AGN. This spectrum reveals absorption lines from H-like and He-like ions of N, O, Ne, Mg, Al, Si, and S. There are also possible absorption lines from H-like and He-like Ar and Ca. We also identify inner-shell absorption from lower-ionization ions such as Si_VII-Si_XII and S_XII-S_XIV. The iron absorption spectrum is very rich; L-shell lines of Fe_XVII-Fe_XXIV are detected, strong complex of M-shell lines, and probable resonance lines from Fe_XXV. The absorption lines are blueshifted relative to the systemic velocity by a mean velocity of -590+-150 km/s. We resolve many of the absorption lines, and their mean FWHM is 820+-280 km/s. We do not find correlations between the velocity shifts or the FWHMs with the ionization potentials of the ions. Most absorption lines show asymmetry, having more extended blue wings than red wings. In O_VII we have resolved this asymmetry to be from an additional absorption system at ~ -1300 km/s. The two X-ray absorption systems are consistent in velocity shift and FWHM with the ones identified in the UV lines of C IV, N V, and H I. Equivalent width measurements for all lines are given and column densities are calculated for several ions. We resolve the narrow Fe_K\alpha line at 6398.2+-3.3 eV to have a FWHM of 1720+-360 km/s, which suggests that this narrow line may be emitted from the outer part of the broad line region or the inner part of the torus. We also detect a `Compton shoulder' redward of the narrow Fe_K\alpha line which indicates that it arises in cold, Compton-thick gas.Comment: 19 pages, 12 figures (2 in color), emulateapj5, accepted for publication in The Astrophysical Journal Supplement

    ANALYSIS OF YELLOW RIVER MIXING PROCESSES INTO THE BO HAI SEA VIA BARIUM AND RADIUM ISOTOPES

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    The mixing rate of dissolved substances from the Yellow River into the Bohai Sea is an important parameter in understanding the nutrient input to the coastal ocean. We present an assessment of the mixing rates under different discharge patterns using naturally-occurring short-lived radium isotopes. Radium and salinity measurements were collected along transects through the Yellow River salinity gradient and into the coastal Bohai Sea during three field expeditions. Mixing rates varied between 5 and 18 km2/day and were strongly dependent on river discharge. The highest mixing rates are found just after periods of high discharge, while the lowest mixing rates occurred after periods of relatively low discharge
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