679 research outputs found

    Effects of the Santa Barbara, Calif., Oil Spill on the Apparent Abundance of Pelagic Fishery Resources

    Get PDF
    Many studies have been made of the effects of oil on marine invertebrates, plants (marine algae and phytoplankton), and vertebrates such as seabirds and marine mammals. An excellent review of these findings, which includes some references to fish and pathological effects of aromatic hydrocarbons, has been published by the Royal Society, London (Clark, 1982). That review dealt with the environmental effects of such major oil spills or releases such as those by the tankers Torry Canyon (119,000 t) on the south coast of England, Metula (50-56,000 t) in the Straits of Magellan, Argo Merchant (26,000 t) off Cape Cod, and the super tanker Amoco Cadiz (223,000 t) on the coast of northern Brittany. Those spills were studied to determine their effect on living resources. In contrast there are few references on the impact of oil spills on pelagic fishery resources

    A Study of the Participation in Leadership Activities in the Area I Federation of the New Farmers of America Organization from 1949-1959

    Get PDF
    Because of the lack of participation of some NFA chapters in leadership activities in Area I, the writer feels that some ways and means to increase participation in leadership activities would be a great asset to Area I in maintaining some of the vocational agricultural departments that are low in membership. Without developing more leaders in the HFA chapters vocational agriculture in the rural communities will suffer. The writer has attempted to analyze the problem on the basis of two fundamental facts. First, presently, all of the NFA chapters in Area I are not fully participating in leadership activities; second, there is a need for more participation on the part of every NFA chapter in Area I, in order for Area I to compete with other areas, states, sectional and national NFA organizations. The participants would be in a position to receive more FFA Foundation Award money given to the NFA organization by donors to help boys to become established in farming. In order to solve the problem an attempt has been made to answer the following questions: 1. To what extent does the membership of each chapter affect participation in leadership activities? 2. To what extent was there participation in the NFA leadership activities in Area I from 1949 to 1959? 3. What are some evidences that there is a need for more participation in the NFA leadership activities in Area I? 4. What are some ways and means of increasing more participation in leadership activities in Area I? The problem was selected because of the small number of chapters that are participating in NFA leadership activities in Area I. The foregoing statement is magnified in the annual reports of the agricultural teachers, which will be treated in a later chapter of this study. Further evidence of inadequate participation in these chapters is revealed in the answers of the various teachers of Area I to the questions asked on the questionnaire. This too, is validated in a later chapter in this study. This study is principally concerned with more participation in NFA leadership activities, emphasizing the number of NFA members participating compared with the number that could be participating in such activities. This was determined by mailing each teacher in Area I a questionnaire with questions on the number of NFA members in each chapter that could participate in the various leadership activities

    North Atlantic tuna explorations

    Get PDF

    Distribution and Apparent Abundance of the Basking Shark, Cetorhinus maximus, off the Central and Southern California Coast, 1962-85

    Get PDF
    Basking sharks, Cetorhinus maximus, are frequently observed along the central and northwestern southern California coast during the winter and spring months. These large plankton feeding elasmobranchs, second in size only to the whale shark, Rhineodon typus, had been the subject of a small commercial fishery off California in the late 1940's and early 1950's for their liver oil, rich in vitamin A, and in later years for reduction into fish meal and oil (Roedel and Ripley, 1950). These fisheries were sporadic and did not take basking sharks in large numbers

    Multiscale Modeling of Grain Boundaries in ZrB2: Structure, Energetics, and Thermal Resistance

    Get PDF
    A combination of ab initio, atomistic and finite element methods (FEM) were used to investigate the structures, energetics and lattice thermal conductance of grain boundaries for the ultra high temperature ceramic ZrB2. Atomic models of idealized boundaries were relaxed using density functional theory. Information about bonding across the interfaces was determined from the electron localization function. The Kapitza conductance of larger scale versions of the boundary models were computed using non-equilibrium molecular dynamics. The interfacial thermal parameters together with single crystal thermal conductivities were used as parameters in microstructural computations. FEM meshes were constructed on top of microstructural images. From these computations, the effective thermal conductivity of the polycrystalline structure was determined

    Does stress perfusion imaging improve the diagnostic accuracy of late gadolinium enhanced cardiac magnetic resonance for establishing the etiology of heart failure?

    Get PDF
    Background Late gadolinium enhanced cardiovascular magnetic resonance (LGE-CMR) has excellent specificity, sensitivity and diagnostic accuracy for differentiating between ischemic cardiomyopathy (ICM) and non-ischemic dilated cardiomyopathy (NICM). CMR first-pass myocardial perfusion imaging (perfusion-CMR) may also play role in distinguishing heart failure of ischemic and non-ischemic origins, although the utility of additional of stress perfusion imaging in such patients is unclear. The aim of this retrospective study was to assess whether the addition of adenosine stress perfusion imaging to LGE-CMR is of incremental value for differentiating ICM and NICM in patients with severe left ventricular systolic dysfunction (LVSD) of uncertain etiology. Methods We retrospectively identified 100 consecutive adult patients (median age 69 years (IQR 59–73)) with severe LVSD (mean LV EF 26.6 ± 7.0%) referred for perfusion-CMR to establish the underlying etiology of heart failure. The cause of heart failure was first determined on examination of CMR cine and LGE images in isolation. Subsequent examination of complete adenosine stress perfusion-CMR studies (cine, LGE and perfusion images) was performed to identify whether this altered the initial diagnosis. Results On LGE-CMR, 38 patients were diagnosed with ICM, 46 with NICM and 16 with dual pathology. With perfusion-CMR, there were 39 ICM, 44 NICM and 17 dual pathology diagnoses. There was excellent agreement in diagnoses between LGE-CMR and perfusion-CMR (κ 0.968, p<0.001). The addition of adenosine stress perfusion images to LGE-CMR altered the diagnosis in only two of the 100 patients. Conclusion The addition of adenosine stress perfusion-CMR to cine and LGE-CMR provides minimal incremental diagnostic yield for determining the etiology of heart failure in patients with severe LVSD

    Nanostructured Thermal Protection Systems for Space Exploration Missions

    Get PDF
    Strong research and development programs in nanotechnology and Thermal Protection Systems (TPS) exist at NASA Ames. Conceptual studies have been undertaken to determine if new, nanostructured materials (composites of existing TPS materials and nanostructured composite fibers) could improve the performance of TPS. To this end, we have studied various candidate heatshields, some composed of existing TPS materials (with known material properties), to provide a baseline for comparison with others that are admixtures of such materials and a nanostructured material. In the latter case, some assumptions were made about the thermal conductivity and strength of the admixture, relative to the baseline TPS material. For the purposes of this study, we have made the conservative assumption that only a small fraction of the remarkable properties of carbon nanotubes (for example) will be realized in the material properties of the admixtures employing them. The heatshields studied included those for Sharp leading edges (appropriate to out-of-orbit entry and aero-maneuvering), probes, an out-of-orbit Apollo Command Module (as a surrogate for NASA's new Crew Exploration Vehicle [CEV]), a Mars Sample Return Vehicle and a large heat shield for Mars aerocapture missions. We report on these conceptual studies, which show that in some cases (not all), significant improvements in the TPS can be achieved through the use of nanostructured materials
    • …
    corecore