4,795 research outputs found

    Evaluating some computer enhancement algorithms that improve the visibility of cometary morphology

    Get PDF
    The observed morphology of cometary comae is determined by ejection circumstances and the interaction of the ejected material with the local environment. Anisotropic emission can provide useful information on such things as orientation of the nucleus, location of active areas on the nucleus, and the formation of ion structure near the nucleus. However, discrete coma features are usually diffuse, of low amplitude, and superimposed on a steep intensity gradient radial to the nucleus. To improve the visibility of these features, a variety of digital enhancement algorithms were employed with varying degrees of success. They usually produce some degree of spatial filtering, and are chosen to optimize visibility of certain detail. Since information in the image is altered, it is important to understand the effects of parameter selection and processing artifacts can have on subsequent interpretation. Using the criteria that the ideal algorithm must enhance low contrast features while not introducing misleading artifacts (or features that cannot be seen in the stretched, unprocessed image), the suitability of various algorithms that aid cometary studies were assessed. The strong and weak points of each are identified in the context of maintaining positional integrity of features at the expense of photometric information

    Recent Case Notes

    Get PDF

    SOIL MICROBIAL COMMUNITY RESPONSE TO CLIMATE CHANGE: RESULTS FROM A TEMPERATE KENTUCKY PASTURE

    Get PDF
    Climate change is likely to alter plant species composition and interactions between plants and soil microbes that together dictate the quantity and quality of forage produced in pastures, the base of animal production in central Kentucky. This study assessed the seasonal dynamics of soil microbes and their response to increased temperature (+3oC) and growing season precipitation (+30% of the mean annual). Total soil microbial biomass, community composition, enzyme activities, potential carbon mineralization, and catabolic responses to selected substrates were measured seasonally in the different climate treatments. In this system, seasonal variability was a dominant driving factor for all the soil microbial characteristics that I investigated. Summer maxima and winter minima were identified in the active microbial biomass, while soil microbial community structure differed between each season. Extracellular enzyme activities were generally highest in either the spring or summer, while seasonal patterns for each substrate were unique across catabolic response profiles. Climate treatments produced few significant main or interactive effects on the soil microbial biomass and function. This resiliency, coupled with evidence of functional redundancy, suggests that central Kentucky pasture ecosystems may be well-equipped to handle future environmental stress associated with climate change and to maintain critical ecosystem services

    Positron Annihilation Ratio Spectroscopy (PsARS) Applied to Positronium Formation Studies

    Get PDF
    A Positron Annihilation of Radiation Spectrometer (PsARS) was developed and characterized. PsARS spectroscopy as well as digital Positron Annihilation Lifetime Spectroscopy (PALS) was applied to measure positronium formation on gold nanoparticles deposited through an evaporative method onto a thin capillary tube. This gold coated capillary tube was designed to be used for positronium lifetime studies in local electric field experiments. High local electric fields can polarize a positron-electron pair, which may result in an extended lifetime of the positron. These fields may be created through the interaction of an external electric field with silver nanoparticles deposited onto the surface of gold coated capillary tubes. The capability to control size and distribution of silver nanoparticles on such a surface is demonstrated. PsARS analysis of potassium dodecahydrododecaborate (dodecaborate) solutions was also performed to verify positronic dodecaborate species as well as potential positronium quenching

    Does Inward Foreign Direct Investment Boost the Productivity of Domestic Firms?

    Get PDF
    Are there productivity spillovers from FDI to domestic firms, and, if so, how much should host countries be willing to pay to attract FDI? To examine these questions we use a plant-level panel covering U.K. manufacturing from 1973 through 1992. Across a wide range of specifications, we estimate a significantly positive correlation between a domestic plant's TFP and the foreign-affiliate share of activity in that plant's industry. This is consistent with positive FDI spillovers. We do not generally find significant effects on plant TFP of the foreign-affiliate share of activity in that plant's region. Typical estimates suggest that a 10 percentage-point increase in foreign presence in a U.K. industry raises the TFP of that industry's domestic plants by about 0.5 percent. We also use these estimates to calculate the per-job value of these spillovers. These calculated values appear to be less than per-job incentives governments have granted in recent high-profile cases, in some cases several times less.

    Does Inward Foreign Direct Investment Boost the Productivity of Domestic Firms?

    Get PDF
    Are there productivity spillovers from FDI to domestic firms, and, if so, how much should host countries be willing to pay to attract FDI? To examine these questions we use a plant-level panel covering U.K. manufacturing from 1973 through 1992. Across a wide range of specifications, we estimate a significantly positive correlation between a domestic plant's TFP and the foreign-affiliate share of activity in that plant's industry. This is consistent with positive FDI spillovers. We do not generally find significant effects on plant TFP of the foreign-affiliate share of activity in that plant's region. Typical estimates suggest that a 10 percentage-point increase in foreign presence in a U.K. industry raises the TFP of that industry's domestic plants by about 0.5 percent. We also use these estimates to calculate the per-job value of these spillovers. These calculated values appear to be less than per-job incentives governments have granted in recent high-profile cases, in some cases several times less.Multinational firms, Foreign direct investment, Productivity spillovers

    Understanding and resolving the global problematique: Assessing the balance between progressive and socially conservative foresight

    Full text link
    Purpose - This paper draws on research undertaken for the State of Play in the Futures Field (SoPiFF) project and aims to explore the contribution of futures work to understanding and resolving aspects of the global problematique and to examine the social interests evident in futures work. Design/methodology/approach - The project used an integral meta-scanning framework to review publicly available futures material. The framework categorizes futures work according to organizational type, social interests, methods, domains and geographic location (details of the methodology are outlined in the accompanying introductory paper as well as on the web site created for the project). Findings - The futures field has made a series of significant contributions to understanding the global problematique and has contributed to the pre-conditions for its resolution. However, the bulk of mainstream futures work does little to improve the preparedness of humanity for looming future crises. More innovative futures work remains marginalized and largely ignored by the powerful and the wider public. There is a strong case for more effective political engagement than has occurred hitherto. Research limitations/implications - Further research is needed on shared definitions for the field, interactions with the media, public and other fields of enquiry and action, measurement of individual foresight capacity, strategies for achieving influence - particularly in the political sphere, the role of subcultures within the futures field and suitable publishing strategies. Practical implications - The paper recommends specific actions to promote and publicize good work, provide annual digests of futures-related information, develop and use focused briefings, provide support for "cutting-edge" futures work, further develop advanced futures methods, create new alliances, build the social capacity for foresight and strengthen the nexus between foresight and philanthropy. Originality/value - The paper uses an integral meta-scanning framework to provide a novel analysis of the futures field. The findings will be of value to all futures and foresight practitioners that are interested in the future success of the field. © Richard A. Slaughter

    Methods used for protein extraction

    Get PDF
    Methods used for protein extractio
    • …
    corecore