15,239 research outputs found

    Cow-Calf Producer Perceptions Regarding Individual Animal Traceability

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    This study provides valuable insights into cow-calf producer voluntary participation in the National Animal Identification System and producers’ perceptions of several issues critically impacting the success of voluntary traceability systems. Cow-calf producers believe that the most important issues to the U.S. beef industry in designing a national, individual animal traceability system are monitoring/managing disease, maintaining current foreign markets, accessing foreign markets, and increasing consumer confidence. Furthermore, producers are concerned with cost, liability, reliability of technology, failure of system to meet stated goals, and confidentiality of information associated with these systems.animal traceability, cow-calf, National Animal Identification System, voluntary adoption, Agribusiness, Community/Rural/Urban Development, Crop Production/Industries, Farm Management, Labor and Human Capital, Land Economics/Use, Livestock Production/Industries, Production Economics, Research and Development/Tech Change/Emerging Technologies, Q12, Q18, R38,

    Approaches and tools to manipulate the carbonate chemistry

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    Although the chemistry of ocean acidifi cation is very well understood (see chapter 1), its impact on marine organisms and ecosystems remains poorly known. The biological response to ocean acidifi cation is a recent field of research, the fi rst purposeful experiments have only been carried out as late as the 1980s (Agegian, 1985) and most were not performed until the late 1990s. The potentially dire consequences of ocean acidifi cation have attracted the interest of scientists and students with a limited knowledge of the carbonate chemistry and its experimental manipulation. Perturbation experiments are one of the key approaches used to investigate the biological response to elevated p(CO2). Such experiments are based on measurements of physiological or metabolic processes in organisms and communities exposed to seawater with normal and altered carbonate chemistry. The basics of the carbonate chemistry must be understood to perform meaningful CO2 perturbation experiments (see chapter 1). Briefl y, the marine carbonate system considers € CO2 ∗(aq) [the sum of CO2 and H2CO3], € HCO3 −, € CO3 2−, H+, € OH− , and several weak acid-base systems of which borate-boric acid (€ B(OH)4 − , B(OH)3) is the most important. As discussed by Dickson (chapter 1), if two components of the carbonate chemistry are known, all the other components can be calculated for seawater with typical nutrient concentrations at given temperature, salinity, and pressure. One of the possible pairs is of particular interest because both components can be measured with precision, accuracy, and are conservative in the sense that their concentrations do not change with temperature or pressure. Dissolved inorganic carbon (DIC) is the sum of all dissolved inorganic carbon species while total alkalinity (AT) equals € [HCO3 − ] + 2 € [CO3 2− ] + € [B(OH)4 − ] + € [OH− ] - [H+] + minor components, and refl ects the excess of proton acceptors over proton donors with respect to a zero level of protons (see chapter 1 for a detailed defi nition). AT is determined by the titration of seawater with a strong acid and thus can also be regarded as a measure of the buffering capacity. Any changes in any single component of the carbonate system will lead to changes in several, if not all, other components. In other words, it is not possible to vary a single component of the carbonate system while keeping all other components constant. This interdependency in the carbonate system is important to consider when performing CO2 perturbation experiments. To adjust seawater to different p(CO2) levels, the carbonate system can be manipulated in various ways that usually involve changes in AT or DIC. The goal of this chapter is (1) to examine the benefi ts and drawbacks of various manipulation methods used to date and (2) to provide a simple software package to assist the design of perturbation experiments
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