RSS 1.0Elmer E. Rasmuson and BioSciences Libraries
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Grey Literature
Alaska and Arctic grey literature collected by the UAF libraries.
Recent Submissions
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Porphyry copper, copper skarn, and volcanogenic massive sulfide occurrences in the Chandalar copper district, AlaskaMetamorphosed porphyry copper, copper skarn, and volcanogenic massive sulfide (VMS) occurrences have been found in 5 key prospects within Devonian rocks of the Chandalar copper district, Alaska. The Venus, Victor, Eva, and Evelyn Lee prospects contain "proximal" porphyry copper/copper skarn mineralization, whereas the Luna prospect contains "distal" Cu-Zn skarn and Cu-Zn VMS mineralization. Porphyry copper mineralization is recognized by granodiorite composition meta-intrusives; zoned potassic, sericitic and propylitic alteration; and del34S values of -1.5 to -0.6 per mil. Skarns consist of andraditic garnet (Ad30-100) and diopsidic pyroxene (Hd9-46), and have del34S values of -4.7 to -1.1 per mil. Alteration types in intrusive rocks and adjacent skarn are generally compatible. VMS occurrences contain chloritic and silicic alteration, and massive sulfides have del34S values of -0.8 to 6.9 per mil, consistent with values from known Devonian VMS deposits.
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Use of Social Media By Alaskan LibrariesThis paper summarizes a survey study of the use of social media by school, public, and academic libraries in Alaska. Librarians at 243 Alaskan libraries were contacted and asked to participate in the study; 83 librarians responded by taking the survey. Results show that public libraries are heavily engaged in social media; academic libraries regularly use social media; and some school libraries use social media but many face school district restrictions on usage. The top reasons Alaskan libraries use social media is to promote library news and events; promote specific resources; and promote specific services. Reasons for not using social media include: not having enough time; social media isn’t deemed as important; and poor Internet connectivity in rural communities. Social media platforms are selected based on librarian preference and comfort level, as opposed to audience characteristics. Libraries that aren’t under prohibitive restrictions, such as policies against using social media or poor internet/bandwidth issues, should frequently reassess their use of social media platforms to best engage with patrons and the community.
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The kinetics of glucose limited growth by a marine yeastThe kinetics of glucose limited growth by a marine yeast, shown to be a Rhodotorula species, have been studied in a continuous culture apparatus. The saturation constant, in synthetic media, has been calculated to be 0.25 mg/l, on the assumption that saturation kinetics are followed, The maximum growth rate was determined in both synthetic media, and artificial sea water. On the basis of inhibition kinetics, the kinetic behavior of this yeast in the marine environment has been predicted. The effect of temperature on the maximum growth rate has been determined and, on the assumption of a similar effect on the saturation constant, the saturation constant has been postulated to be in agreement with similar values determined for other microorganisms.
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Small spatial and fast temporal ionosphere -magnetosphere coupling processesI have developed a two-dimensional, three-fluid model (electrons, ions and neutrals) to simulate small-scale magnetosphere-ionosphere coupling processes. The code includes ionization and recombination processes, the Hall term in Ohm's law, and various heat sources in the energy equations. The electro-dynamic response and the evolution of the collision frequencies are treated self-consistently in a height resolved ionosphere. The model allows for the propagation of Alfven waves. The simulation is particularly suited for fast temporal variations and small spatial scale ionospheric structures associated with filamentary aurora and ionospheric heating experiments (e.g. HAARP). I have investigated the evolution of field-aligned currents in the magnetosphere-ionosphere system and found several notable effects---ion heating due to plasma-neutral friction, electron heating resulting from energetic particle precipitation and ohmic dissipation by strong field-aligned currents. The simulation of plasma. heating in the ionosphere is motivated by a specific auroral event that was simultaneously observed with optical and radar instruments. The results indicate that a consistent explanation of this event requires ohmic heating of electrons in a strong field-aligned electric current layer. They suggest strongly that the observed sequence of events can be explained only if spatial structure is present in the ionosphere so that it requires at least a two-dimensional model. Electron heating in strong field-aligned currents also provides a mechanism to deposit energy in the F-region of ionosphere and thus can explain the formation of tall auroral arcs. The simulation of the formation of field-aligned currents shows a strong plasma density depletion in the region of downward field-aligned current layer. The depletion is due to the divergent flow of the plasma. Similarly, the plasma density increases in the region of upward field-aligned current because of the convergent plasma motion. A modification of the ionospheric conditions by localized particle precipitation has an interesting effect. At the edge of the precipitation region, a new field-aligned current filament is formed. Finally, the simulation code is not limited by steady state assumptions commonly used for the Hall model and Pedersen conductivities.
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Modeling of Arctic stratus cloud formation and the maintenance of the cloudy Arctic boundary layerThe formation of Arctic stratus clouds (ASCs) and the maintenance of the cloudy Arctic boundary layer are studied with two models: a one-dimensional radiative-convective model and a three-dimensional large eddy simulation (LES) model. The one-dimensional radiative-convective model consists of a comprehensive radiative module, a cloud parameterization with detailed microphysics and a convective adjustment scheme. The model is designed specifically for studying ASC formation. With this model, the roles of radiation and cloud microphysics in the formation of ASCs and multiple cloud layers are investigated. The simulations reproduce both single and multiple cloud layers that were observed with inversions of temperature and humidity occurring near the cloud top. The detailed cloud microstructure produced by the model also compares well with the observations. The physics of the formation of both single and multiple cloud layers is investigated. Radiative cooling plays a key role during the initial stage of cloud formation in a atmosphere. It leads to a continual temperature decrease promoting water vapor condensation on available cloud condensation nuclei. The vertical distribution of humidity and temperature determines the radiative cooling and eventually where and when the cloud forms. The observed temperature inversion may also be explained by radiative cooling. The three-dimensional LES model is adopted to evaluate the one-dimensional model, especially the convective adjustment scheme. The advantages and limitations of the one-dimensional model are discussed. The LES results suggest that the convective adjustment scheme is capable of capturing the main features of the vertical heat and moisture fluxes in the cloudy Arctic boundary layer. The LES model is also used to investigate the maintenance of the cloudy Arctic boundary layer. The turbulence in the cloudy Arctic boundary layer is primarily maintained by the buoyancy effect due to the cloud top cooling. It is found that weak large scale downward motion aids in cloud development and maintenance.
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Single and multiple electromagnetic scattering by size -shape distributions of small nonspherical particlesA comprehensive model for light scattering by size-shape distributions of randomly oriented nonspherical particles is developed. The model uses spheroids as model particles. The vector Helmholtz equation is solved with a new separation of variables (SVM) approach that allows one to calculate the ensemble-averaged single scattering optical properties of ensembles of randomly oriented particles analytically. Since the use of the SVM in spheroidal coordinates properly accounts for the geometry of the particles, the method is applicable to a large range of shapes ranging from elongated prolate needles via spheres to flat oblate disks. The relation between geometric symmetries of particles and symmetry relations of the electromagnetic scattering solution is investigated systematically in the general framework of the theory of point groups. The results are exploited in the model for increasing the computational efficiency. A comprehensive vector radiative transfer model is in part developed in this work. This radiative transfer model takes the output of the single scattering model as input and computes the Stokes vector components in a vertically inhomogeneous, plane parallel medium as a function of polar and azimuth angle and as a function of optical depth. The single scattering model is applied to investigate the impact of particle shape on the optical properties of size-shape distributions of randomly oriented particles, such as aerosol layers or ice clouds in the atmosphere. The optical properties are found to be much more sensitive to a variation in the effective aspect ratio than to a variation in the effective variance of a shape-distribution. The results of this study are used as input to the vector radiative transfer model in order to study the shape-sensitivity of the radiation field in a macroscopic medium containing a size-shape distribution of randomly oriented particles. It is found that both the radiance, and the degree of linear polarization, and the degree of circular polarization are strongly shape-sensitive in most viewing directions.
