837 research outputs found

    ECONOMIC SURPLUS AND THE DISTRIBUTIONAL CONSEQUENCES OF DEREGULATING TOBACCO PRODUCTION

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    Reservations on technical and theoretical grounds in the use of the consumer surplus approach to measure benefits of government programs have often appeared in the literature. Therefore, this paper uses an alternative approach in a case study to estimate the annual economic surplus created in South Carolina from deregulating tobacco production. Impacts of deregulation on cropping patterns and income on representative tobacco farms, and distribution of benefits in the economy are examined. Results of this study indicate that deregulation stimulates the economy and would increase the net value added by $5.8 million in the long run.Agricultural and Food Policy,

    Hubungan Asam Lemak Rantai Pendek, Stratifikasi, dan Giberelin pada Perkecambahan Embrio Apel

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    The objective of the present experiment was to determine the inhibitory properties of short chain fatty acids (SCFA) in apple embryo germination. The result showed that the SCFA inhibition on apple embryo germination was dependent on chain length and was in the millimolar range. No synergistic effect was observed when SCFA were applied simultaneously. The inhibition of SCFA was reversed by GA4+7. A higher concentration of SCFA was needed to inhibit embryo germination as the stratification progressed

    HAZMAT VI: The Evolution of Extreme Ultraviolet Radiation Emitted from Early M Star

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    Quantifying the evolution of stellar extreme ultraviolet (EUV, 100 -- 1000 A\overset{\circ}{A}) emission is critical for assessing the evolution of planetary atmospheres and the habitability of M dwarf systems. Previous studies from the HAbitable Zones and M dwarf Activity across Time (HAZMAT) program showed the far- and near-UV (FUV, NUV) emission from M stars at various stages of a stellar lifetime through photometric measurements from the Galaxy Evolution Explorer (GALEX). The results revealed increased levels of short-wavelength emission that remain elevated for hundreds of millions of years. The trend for EUV flux as a function of age could not be determined empirically because absorption by the interstellar medium prevents access to the EUV wavelengths for the vast majority of stars. In this paper, we model the evolution of EUV flux from early M stars to address this observational gap. We present synthetic spectra spanning EUV to infrared wavelengths of 0.4 ±\pm 0.05 M_{\odot} stars at five distinct ages between 10 and 5000 Myr, computed with the PHOENIX atmosphere code and guided by the GALEX photometry. We model a range of EUV fluxes spanning two orders of magnitude, consistent with the observed spread in X-ray, FUV, and NUV flux at each epoch. Our results show that the stellar EUV emission from young M stars is 100 times stronger than field age M stars, and decreases as t1^{-1} after remaining constant for a few hundred million years. This decline stems from changes in the chromospheric temperature structure, which steadily shifts outward with time. Our models reconstruct the full spectrally and temporally resolved history of an M star's UV radiation, including the unobservable EUV radiation, which drives planetary atmospheric escape, directly impacting a planet's potential for habitability.Comment: 23 pages, 15 figures, accepted to Ap

    Corn and grain sorghum response to limited irrigation, drought, and hail

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    A field study was conducted for eight years in southwest Kansas near Garden City to measure the response of corn and grain sorghum to limited irrigation in the region. An irrigation variable was imposed on each crop, with six irrigation treatments from full irrigation scheduled to minimize soil water deficits to minimal or no irrigation. To create differences in the amount of irrigation across treatments, the time between 25-mm irrigation events increased as irrigation decreased. A historic drought occurred during 2011 and 2012 when cropping season precipitation, the precipitation occurring from the harvest of the prior crop through the harvest of the next crop, was 60% of the 30-year average. Except for 2008, average cropping season precipitation was 8% above average during the prior six years. Linear regressions of corn and sorghum grain yields (GY) and dry matter yields (DMY) versus crop evapotranspiration (ETc) from all years combined, except hail damaged sorghum in 2005, produced R2 values from 0.71 to 0.79. One hailstorm during 2005 damaged sorghum to the extent that yields did not vary with respect to ETc or irrigation. Hail events in 2005 and 2006 occurred at nearly the same growth stage for corn caused lower leaf area and yields than during other wet years with no hail. Using quadratic regressions, corn yields during wet years with no hail, wet years with hail, and dry years had distinctly different dependence on irrigation. Although sorghum yields during wet years tended to increase as irrigation increased, sorghum’s response to irrigation was less than for corn during the same years. During dry years, sorghum and corn were highly dependent on irrigation. Net economic returns (NR) of continuous corn, continuous sorghum, cornsorghum, corn-wheat, and sorghum-wheat rotations were each higher with a year receiving average precipitation (460 mm) than a year receiving 60% of average precipitation (280 mm). The NR of continuous corn dominated the rest of the rotations when irrigation was more than 230 to 330 mm in the dry year and 90 to 180 mm in wet year. As farmers choose crop rotations, they need to consider management factors and crop tolerance to soil water stress in addition to potential NR

    Social Category Diversity Promotes Premeeting Elaboration: The Role of Relationship Focus

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    A purported downside of social category diversity is decreased relationship focus (i.e., one’s focus on establishing a positive social bond with a coworker). However, we argue that this lack of relationship focus serves as a central mechanism that improves information processing even prior to interaction and, ultimately, decision-making performance in diverse settings. We introduce the construct of premeeting elaboration (i.e., the extent to which individuals consider their own and others’ perspectives in the anticipation of an interaction) and explore its link with social category diversity and relationship focus. Experiments 1 and 2 demonstrate that when disagreement occurs, social category diversity increases premeeting elaboration, with relationship focus as a central causal mechanism. Experiment 3 shows that premeeting elaboration has important implications for performance: disagreeing dyads with social category diversity elaborate more prior to meeting and, as a result, perform better on a decision-making task than those with social category homogeneity. We discuss the value of studying early-stage interaction and propose a reconsideration of the “downside” of social category diversity.Kellogg School of Managemen

    This New Ocean: A History of Project Mercury

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    When Congress created the National Aeronautics and Space Administration (NASA) in 1958, it charged NASA with the responsibility "to contribute materially to . . . the expansion of human knowledge of phenomena in the atmosphere and space" and "provide for the widest practicable and appropriate dissemination of information concerning its activities and the results thereof." NASA wisely interpreted this mandate to include responsibility for documenting the epochal progress of which it is the focus. The result has been the development of a historical program by NASA as unprecedented as the task of extending man's mobility beyond his planet. This volume is not only NASA's accounting of its obligation to disseminate information to our current generation of Americans. It also fulfills, as do all of NASA's future-oriented scientific-technological activities, the further obligation to document the present as the heritage of the future. The wide-ranging NASA history program includes chronicles of day-to-day space activities; specialized studies of particular fields within space science and technology; accounts of NASA's efforts in organization and management, where its innovations, while less known to the public than its more spectacular space shots, have also been of great significance; narratives of the growth and expansion of the space centers throughout the country, which represent in microcosm many aspects of NASA's total effort; program histories, tracing the successes- and failures- of the various projects that mark man's progress into the Space Age; and a history of NASA itself, incorporating in general terms the major problems and challenges, and the responses thereto, of our entire civilian space effort. The volume presented here is a program history, the first in a series telling of NASA's pioneering steps into the Space Age. It deals with the first American manned-spaceflight program: Project Mercury. Although some academicians might protest that this is "official" history, it is official only in the fact that it has been prepared and published with the support and cooperation of NASA. It is not "official" history in the sense of presenting a point of view supposedly that of NASA officialdom-if anyone could determine what the "point of view" of such a complex organism might be. Certainly, the authors were allowed to pursue their task with the fullest freedom and in accordance with the highest scholarly standards of the history profession

    The MUSCLES Treasury Survey. V. FUV Flares on Active and Inactive M Dwarfs

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    M dwarf stars are known for their vigorous flaring. This flaring could impact the climate of orbiting planets, making it important to characterize M dwarf flares at the short wavelengths that drive atmospheric chemistry and escape. We conducted a far-ultraviolet flare survey of 6 M dwarfs from the recent MUSCLES (Measurements of the Ultraviolet Spectral Characteristics of Low-mass Exoplanetary Systems) observations, as well as 4 highly-active M dwarfs with archival data. When comparing absolute flare energies, we found the active-M-star flares to be about 10×\times more energetic than inactive-M-star flares. However, when flare energies were normalized by the star's quiescent flux, the active and inactive samples exhibited identical flare distributions, with a power-law index of -0.760.09+0.10.76^{+0.1}_{-0.09} (cumulative distribution). The rate and distribution of flares are such that they could dominate the FUV energy budget of M dwarfs, assuming the same distribution holds to flares as energetic as those cataloged by Kepler and ground-based surveys. We used the observed events to create an idealized model flare with realistic spectral and temporal energy budgets to be used in photochemical simulations of exoplanet atmospheres. Applied to our own simulation of direct photolysis by photons alone (no particles), we find the most energetic observed flares have little effect on an Earth-like atmosphere, photolyzing \sim0.01% of the total O3_3 column. The observations were too limited temporally (73 h cumulative exposure) to catch rare, highly energetic flares. Those that the power-law fit predicts occur monthly would photolyze \sim1% of the O3_3 column and those it predicts occur yearly would photolyze the full O3_3 column. Whether such energetic flares occur at the rate predicted is an open question.Comment: Accepted to ApJ. v2 fixed some transposed errors, added PDF To

    HUBUNGAN ASAM LEMAK RANTAI PENDEK, STRATIFIKASI, DAN GIBERELIN PADA PERKECAMBAHAN EMBRIO APEL

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    The objective of the present experiment was to determine the inhibitory properties of short chain fatty acids (SCFA) in apple embryo germination. The result showed that the SCFA inhibition on apple embryo germination was dependent on chain length and was in the millimolar range. No synergistic effect was observed when SCFA were applied simultaneously. The inhibition of SCFA was reversed by GA4+7. A higher concentration of SCFA was needed to inhibit embryo germination as the stratification progressed
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