4,046 research outputs found

    Chronic Copper Poisoning and Pancreatitis in Sheep

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    During the fall of 1958 a prominent sheep breeder in central Iowa began to lose some sheep. On October 12, 1958, a ram showed anorexia, and appeared as if he were in pain. Upon palpation, tenderness was noted on the right side of the abdomen, and central nervous system disturbances appeared prior to his death. When he became recumbent, he showed running movements and foamed at the mouth. A necropsy examination was not made

    Differentiation mechanisms in a calc-alkaline lava series from the island of Aegina, Aegean Sea, Greece

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    Major and trace element and isotopic modelling was performed on four representative lava samples from the island of Aegina, Aegean Sea, using data obtained from Barton et al. (1985). Aegina is situated on the western-most end of the Hellenic volcanic arc, in which one continental plate is being subducted beneath another. Major oxide variations suggest differentiation largely via fractional crystallization, and mixing models support this theory. 87Sr/86Sr behavior lends evidence to the probability of assimilation, most prominent in the early stages of differentiation. Failure to predict the effects of combined assimilation and fractional crystallization suggests the use of inaccurate values of Sr (ppm) and 87Sr/86Sr for the crust. However, the results presented provide useful information for the interpretation of destructional plate environments.No embarg

    Urban Evolution: The Role of Water

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    The structure, function, and services of urban ecosystems evolve over time scales from seconds to centuries as Earth’s population grows, infrastructure ages, and sociopolitical values alter them. In order to systematically study changes over time, the concept of “urban evolution” was proposed. It allows urban planning, management, and restoration to move beyond reactive management to predictive management based on past observations of consistent patterns. Here, we define and review a glossary of core concepts for studying urban evolution, which includes the mechanisms of urban selective pressure and urban adaptation. Urban selective pressure is an environmental or societal driver contributing to urban adaptation. Urban adaptation is thesequential process by which an urban structure, function, or services becomes more fitted to its changing environment or human choices. The role of water is vital to driving urban evolution as demonstrated by historical changes in drainage, sewage flows, hydrologic pulses, and long-term chemistry. In the current paper, we show how hydrologic traits evolve across successive generations of urban ecosystems via shifts in selective pressures and adaptations over time. We explore multiple empirical examples including evolving: (1) urban drainage from stream burial to stormwater management; (2) sewage flows and water quality in response to wastewater treatment; (3) amplification of hydrologic pulses due to the interaction between urbanization and climate variability; and (4) salinization and alkalinization of fresh water due to human inputs and accelerated weathering. Finally, we propose a new conceptual model for the evolution of urban waters from the Industrial Revolution to the present day based on empirical trends and historical information. Ultimately, we propose that water itself is a critical driver of urban evolution that forces urban adaptation, which transforms the structure, function, and services of urban landscapes, waterways, and civilizations over time

    Characterizing the Response of Composite Panels to a Pyroshock Induced Environment using Design of Experiments Methodology

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    This experimental study seeks to quantify the impact various composite parameters have on the structural response of a composite structure in a pyroshock environment. The prediction of an aerospace structure's response to pyroshock induced loading is largely dependent on empirical databases created from collections of development and flight test data. While there is significant structural response data due to pyroshock induced loading for metallic structures, there is much less data available for composite structures. One challenge of developing a composite pyroshock response database as well as empirical prediction methods for composite structures is the large number of parameters associated with composite materials. This experimental study uses data from a test series planned using design of experiments (DOE) methods. Statistical analysis methods are then used to identify which composite material parameters most greatly influence a flat composite panel's structural response to pyroshock induced loading. The parameters considered are panel thickness, type of ply, ply orientation, and pyroshock level induced into the panel. The results of this test will aid in future large scale testing by eliminating insignificant parameters as well as aid in the development of empirical scaling methods for composite structures' response to pyroshock induced loading

    Biogenic Matter Diagenesis on the Sea Floor: A Comparison Between Two Continental Margin Transects

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    Benthic chamber measurements of the reactants and products involved with biogenic matter diagenesis (oxygen, ammonium, nitrate, silicate, phosphate, TCO2, alkalinity) were used to define fluxes of these solutes into and out of the sediments off southern and central California. Onshore to offshore transects indicate many similarities in benthic fluxes between these regions. The pattern of benthic organic carbon oxidation as a function of water depth, combined with published sediment trap records, suggest that the supply of organic carbon from vertical rain can just meet the sedimentary carbon oxidation + burial demand for the central California region between the depths 100-3500 m. However, there is not enough organic carbon raining through the upper water column to support its oxidation and burial in the basins off southern California. Lateral transport and focusing of refractory carbon within these basins is proposed to account for the carbon buried. The organic carbon burial efficiency is greater off southern California (40-60%) compared to central California (2-20%), even though carbon rain rates are comparable. Oxygen uptake rates are not sensitive to bottom water oxygen concentrations nor to the bulk wt. % organic carbon in surficial sediments. Nitrate uptake rates are well defined by the depth of oxygen penetration into the sediments and the overlying water column nitrate concentration. Nitrate uptake accounts for about 50% of the total denitrification taking place in shelf sediments and denitrification (0.1-1.0 mmolN/m2d) occurs throughout the entire study region. The ratio of carbon oxidized to opal dissolved on the sea floor is constant (0.8 ± 0.2) through a wide range of depths, supporting the hypothesis that opal dissolution kinetics may be dominated by a highly reactive phase. Sea floor carbonate dissolution is negligible within the oxygen minimum zone and reaches maximal rates just above and below this zone (0.2-2.0 mmol/m2d)

    The Triple Symbiotic System CH Cygni

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    Analysis of high-resolution IR spectra of CH Cygni shows that the star is a triple system with a short period orbit of just over 2 yrs. The period ratio of seven for CH Cyg is the smallest known for a triple system. The symbiotic pair is the short-period system. An eccentric and a circular orbit solution are determined for the short-period pair, and the circular orbit solution is found to be more appropriate. The observed eccentricity appears to be due to phase-dependent line asymmetries resulting from the irradiation of the M giant by the white dwarf. The system does not eclipse. The most consistent mode of the system is a short-period pair consisting of an M6 giant of two solar masses that is within a factor of two of filling its Roche lobe and a white dwarf of 0.2 solar mass. The orbital inclination is about 70 deg. The unseen third star in the system is probably a G-K dwarf

    The Full-sky Astrometric Mapping Explorer -- Astrometry for the New Millennium

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    FAME is designed to perform an all-sky, astrometric survey with unprecedented accuracy. It will create a rigid astrometric catalog of 4x10^7 stars with 5 < m_V < 15. For bright stars, 5 < m_V < 9, FAME will determine positions and parallaxes accurate to < 50 microarcseconds, with proper motion errors < 50 microarcseconds/year. For fainter stars, 9 < m_V < 15, FAME will determine positions and parallaxes accurate to < 500 microarcseconds, with proper motion errors < 500 microarcseconds/year. It will also collect photometric data on these 4 x 10^7 stars in four Sloan DSS colors.Comment: 6 pages, 4 figures, to appear in "Working on the Fringe

    The Argo Program : present and future

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    Author Posting. © The Oceanography Society, 2017. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 30, no. 2 (2017): 18–28, doi:10.5670/oceanog.2017.213.The Argo Program has revolutionized large-scale physical oceanography through its contributions to basic research, national and international climate assessment, education, and ocean state estimation and forecasting. This article discusses the present status of Argo and enhancements that are underway. Extensions of the array into seasonally ice-covered regions and marginal seas as well as increased numbers of floats along the equator and around western boundary current extensions have been proposed. In addition, conventional Argo floats, with their 2,000 m sampling limit, currently observe only the upper half of the open ocean volume. Recent advances in profiling float technology and in the accuracy and stability of float-mounted conductivity-temperature-depth sensors make it practical to obtain measurements to 6,000 m. The Deep Argo array will help observe and constrain the global budgets of heat content, freshwater, and steric sea level, as well as the full-depth ocean circulation. Finally, another extension to the Argo Program is the addition of a diverse set of chemical sensors to profiling floats in order to build a Biogeochemical-Argo array to understand the carbon cycle, the biological pump, and ocean acidification.S.R.J. was supported by US Argo Program through NOAA Grant NA14OAR4320158 (CINAR). D.R. and N.Z. were supported by the US Argo Program through NOAA Grant NA10OAR4310139 (CIMEC). S.C.R. was supported by the US Argo Program through NOAA Grants NAOAR4320063 and NA16OAR4310161 (JISAO). K.S.J. was supported by the David and Lucile Packard Foundation and by the Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) Project funded by National Science Foundation, Division of Polar Programs (NSF PLR-1425989). G.C.J. is supported by the Ocean Observations and Monitoring Division, Climate Program Office, National Oceanic and Atmospheric Administration (NOAA), US Department of Commerce and NOAA Research
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