8,798 research outputs found

    Lyman Alpha and MgII as Probes of Galaxies and their Environments

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    Ly{\alpha} emission, Ly{\alpha} absorption and MgII absorption are powerful tracers of neutral hydrogen. Hydrogen is the most abundant element in the universe and plays a central role in galaxy formation via gas accretion and outflows, as well as being the precursor to molecular clouds, the sites of star formation. Since 21cm emission from neutral hydrogen can only be directly observed in the local universe, we rely on Ly{\alpha} emission, and Ly{\alpha} and MgII absorption to probe the physics that drives galaxy evolution at higher redshifts. Furthermore, these tracers are sensitive to a range of hydrogen densities that cover the interstellar medium, the circumgalactic medium and the intergalactic medium, providing an invaluable means of studying gas physics in regimes where it is poorly understood. At high redshift, Ly{\alpha} emission line searches have discovered thousands of star-forming galaxies out to z = 7. The large Ly{\alpha} scattering cross-section makes observations of this line sensitive to even very diffuse gas outside of galaxies. Several thousand more high-redshift galaxies are known from damped Ly{\alpha} absorption lines and absorption by the MgII doublet in quasar and GRB spectra. MgII, in particular, probes metal-enriched neutral gas inside galaxy haloes in a wide range of environments and redshifts (0.1 < z < 6.3), including the so-called redshift desert. Here we review what observations and theoretical models of Ly{\alpha} emission, Ly{\alpha} and MgII absorption have told us about the interstellar, circumgalactic and intergalactic medium in the context of galaxy formation and evolution.Comment: 59 Pages, 19 Figures, 1 Table. Accepted for publication in Publications of the Astronomical Society of the Pacifi

    The teaching of handwriting

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    Submitted in partial fulfillment of the requirements for the degree of Master of Arts.Text from page 1: The problem of this investigation is to study the uses of diagnosis and corrective measures in the teaching of handwriting.Includes bibliographic references

    Integrable families of hard-core particles with unequal masses in a one-dimensional harmonic trap

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    We show that the dynamics of particles in a one-dimensional harmonic trap with hard-core interactions can be solvable for certain arrangements of unequal masses. For any number of particles, there exist two families of unequal mass particles that have integrable dynamics, and there are additional exceptional cases for three, four and five particles. The integrable mass families are classified by Coxeter reflection groups and the corresponding solutions are Bethe ansatz-like superpositions of hyperspherical harmonics in the relative hyperangular coordinates that are then restricted to sectors of fixed particle order. We also provide evidence for superintegrability of these Coxeter mass families and conjecture maximal superintegrability.Comment: 9.5+4.5 pages, 5 figures, 2 tables; v3: a few corrections and addition

    Anomalous Scaling and Solitary Waves in Systems with Non-Linear Diffusion

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    We study a non-linear convective-diffusive equation, local in space and time, which has its background in the dynamics of the thickness of a wetting film. The presence of a non-linear diffusion predicts the existence of fronts as well as shock fronts. Despite the absence of memory effects, solutions in the case of pure non-linear diffusion exhibit an anomalous sub-diffusive scaling. Due to a balance between non-linear diffusion and convection we, in particular, show that solitary waves appear. For large times they merge into a single solitary wave exhibiting a topological stability. Even though our results concern a specific equation, numerical simulations supports the view that anomalous diffusion and the solitary waves disclosed will be general features in such non-linear convective-diffusive dynamics.Comment: Corrected typos, added 3 references and 2 figure

    Analisis Kesesuaian Perairan Untuk Budidaya Ikan Kerapu Macan (Epinephelus Fuscoguttatu) Di Perairan Pulau Tegal Kecamatan Teluk Pandan Kabupaten Pesawaran

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    Tiger grouper is a marine aquaculture commodities that has good prospects to be developed. One of the areas that could potentially be used as a place of tiger grouper fish farming is the Tegal Island, Pesawaran. The purpose of this research was to analyze the level of water quality for fish farming tiger grouper (Epinephelus fuscoguttatus). This research was carried out in March-May 2017 descriptive analytic nature by doing the observations on the quality of waters which include physical and chemical parameters. The data that used in this research sourced from primary data about the suitability waters of the island while the secondary data is form in research location maps. There were 4 sampling stations which determined with global positioning system (GPS). The results showed that the water quality which is owned by the island's waters on station 1, 2, 3 and 4 were in the quite appropriate category for the cultivation of tiger grouper
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