260 research outputs found

    Faculty Status for Librarians: Retrospect and Prospect

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    The article examines the history of faculty status for academic librarians and the attempts to relieve them of this status

    Alien Registration- Josey, Alice E. (Lewiston, Androscoggin County)

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    https://digitalmaine.com/alien_docs/28853/thumbnail.jp

    Predicting cerium + H2O cluster formation with simulated and experimental spectroscopy

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    \begin{wrapfigure}{r}{0pt} \includegraphics[scale=0.8]{ISMS Abstract Image.eps} \end{wrapfigure} Ceria (CeO2_{2}) has been established as a good support in heterogeneous catalysts for the water gas shift reaction. This study looks into cerium’s reactivity with water, a water gas shift reagent, and aims to build an understanding of the three reactions which can occur: direct oxidation, -OH abstraction, and H2_{2}O addition. Through the use of anion photoelectron spectroscopy and density functional theory calculations we have been able to determine that the reactivity is dependent on (1) the oxidation states of the metal centers, (2) the availability of 5d orbitals to form metal oxide bonds, and (3) the presence of electrons in the 6s orbital. The results of this study can be used to inform design of catalytic materials for the water gas shift reaction

    SAMARIUM DOPED CERIUM OXIDE CLUSTERS: A STUDY ON THE MODULATION OF ELECTRONIC STRUCTURE

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    begin{wrapfigure}{r}{0pt}_x000d_ includegraphics[scale=0.9]{ISMS 2017 Abstract2.eps}_x000d_ end{wrapfigure}_x000d_ Cerium oxide is known for its use in solid oxide fuel cells due to its high ionic conductivity. The doping of trivalent samarium atoms into cerium oxide is known to enhance the ionic conductivity through the generation of additional oxygen vacancies. This study probes the electronic structure of Smx_{x}Cey_{y}Oz_{z} ({it x}+{it y}=3, {it z}=2-4) anion and neutral clusters. Anion photoelectron spectra of these mixed metal clusters exhibit additional spectral features not present in the previously studied cerium oxide clusters. Density functional theory calculations have been used to aid interpretation of collected spectra. The results of this work can be used to inform the design of materials used for solid oxide fuel cells

    INTERROGATION OF MoOyCnHn− CHEMIFRAGMENTS ILLUMINATES Mo−(η2−ACETYLENE) INTERACTIONS WITHIN MoxOy− AND ETHYLENE REACTIONS

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    In an effort to determine the feasibility of producing hydrogen gas via H2_2O + C2_2H4_4 →\rightarrow H2_2 + CH3_3CHO, cluster reactivity studies were completed between Mox_xOy_y cluster anions and H2_2O, C2_2H4_4, and mixtures of both H2_2O and C2_2H4_4. These studies unveiled the evolution of several chemifragmentation products. To better understand the molecular-scale interactions along these chemifragmentation pathways, the photoelectron spectra and supporting theoretical calculations were analyzed for each cluster. In this talk, spectra and computational results for a series of monometallic chemifragment cluster anions formed from reactions with C2_2H4_4 will be presented. The analysis indicates that experimental spectra are most consistent with η\eta2^2−-acetylene complexes, however vinylidene complexes cannot be definitively ruled out for all clusters. The results of this work deepen our understanding of the side reactions which occur in this multi-reactant system

    The sensitivity of southeast pacific heat distribution to local and remote changes in ocean properties

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    AbstractThe Southern Ocean features ventilation pathways that transport surface waters into the subsurface thermocline on time scales from decades to centuries, sequestering anomalies of heat and carbon away from the atmosphere and thereby regulating the rate of surface warming. Despite its importance for climate sensitivity, the factors that control the distribution of heat along these pathways are not well understood. In this study, we use an observationally constrained, physically consistent global ocean model to examine the sensitivity of heat distribution in the recently ventilated subsurface Pacific (RVP) sector of the Southern Ocean to changes in ocean temperature and salinity. First, we define the RVP using numerical passive tracer release experiments that highlight the ventilation pathways. Next, we use an ensemble of adjoint sensitivity experiments to quantify the sensitivity of the RVP heat content to changes in ocean temperature and salinity. In terms of sensitivities to surface ocean properties, we find that RVP heat content is most sensitive to anomalies along the Antarctic Circumpolar Current (ACC), upstream of the subduction hotspots. In terms of sensitivities to subsurface ocean properties, we find that RVP heat content is most sensitive to basin-scale changes in the subtropical Pacific Ocean, around the same latitudes as the RVP. Despite the localized nature of mode water subduction hotspots, changes in basin-scale density gradients are an important controlling factor on heat distribution in the southeast Pacific.</jats:p

    Major variations in subtropical North Atlantic heat transport at short (5 day) timescales and their causes

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    Variability in the North Atlantic ocean heat transport at 26.5°N on short (5-day) timescales is identified and contrasted with different behaviour at monthly intervals using a combination of RAPID/MOCHA/WBTS measurements and the NEMO-LIM2 1/12° ocean circulation/sea ice model. Wind forcing plays the leading role in establishing the heat transport variability through the Ekman transport response of the ocean and the associated driving atmospheric conditions vary significantly with timescale. We find that at 5-day timescales the largest changes in the heat transport across 26.5°N coincide with north-westerly airflows originating over the American land mass that drive strong southward anomalies in the Ekman flow. During these events the northward heat transport reduces by 0.5-1.4 PW. In contrast, the Ekman transport response at longer monthly timescales is smaller in magnitude (up to 0.5 PW) and consistent with expected variations in the leading mode of North Atlantic atmospheric variability, the North Atlantic Oscillation. The north-westerly airflow mechanism can have a prolonged influence beyond the central 5-day timescale and on occasion can reduce the accumulated winter ocean heat transport into the North Atlantic by ∌40%

    Extreme air–sea interaction over the North Atlantic subpolar gyre during the winter of 2013–2014 and its sub-surface legacy

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    Exceptionally low North American temperatures and record-breaking precipitation over the British Isles during winter 2013–2014 were interconnected by anomalous ocean evaporation over the North Atlantic subpolar gyre region (SPG). This evaporation (or oceanic latent heat release) was accompanied by strong sensible heat loss to the atmosphere. The enhanced heat loss over the SPG was caused by a combination of surface westerly winds from the North American continent and northerly winds from the Nordic Seas region that were colder, drier and stronger than normal. A distinctive feature of the air–sea exchange was that the enhanced heat loss spanned the entire width of the SPG, with evaporation anomalies intensifying in the east while sensible heat flux anomalies were slightly stronger upstream in the west. The immediate impact of the strong air–sea fluxes on the ocean–atmosphere system included a reduction in ocean heat content of the SPG and a shift in basin-scale pathways of ocean heat and atmospheric freshwater transport. Atmospheric reanalysis data and the EN4 ocean data set indicate that a longer-term legacy of the winter has been the enhanced formation of a particularly dense mode of Subpolar Mode Water (SPMW)—one of the precursors of North Atlantic Deep Water and thus an important component of the Atlantic Meridional Overturning Circulation. Using particle trajectory analysis, the likely dispersal of newly-formed SPMW is evaluated, providing evidence for the re-emergence of anomalously cold SPMW in early winter 2014/2015

    Production of highly-polarized positrons using polarized electrons at MeV energies

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    The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-ZZ target. Positron polarization up to 82\% have been measured for an initial electron beam momentum of 8.19~MeV/cc, limited only by the electron beam polarization. This technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community.Comment: 5 pages, 4 figure
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