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Galaxies, and clusters of galaxies, can act as gravitational lenses and magnify the light of objects behind them. The effect enables observations of very distant supernovae, that otherwise would be too faint to be detected by existing telescopes, and allows studies of the frequency and properties of these rare phenomena when the universe was young. Under the right circumstances, multiple images of the lensed supernovae can be observed, and due to the variable nature of the objects, the difference between the arrival times of the images can be measured. Since the images have taken different paths through space before reaching us, the time-differences are sensitive to the expansion rate of the universe. One class of supernovae, Type Ia, are of particular interest to detect. Their well known brightness can be used to determine the magnification, which can be used to understand the lensing systems. In this thesis, galaxy clusters are used as gravitational telescopes to search for lensed supernovae at high redshift. Ground-based, near-infrared and optical search campaigns are described of the massive clusters Abell 1689 and 370, which are among the most powerful gravitational telescopes known. The search resulted in the discovery of five photometrically classified, core-collapse supernovae at redshifts of 0.671&lt;z&lt;1.703 with significant magnification from the cluster. Owing to the power of the lensing cluster, the volumetric core-collapse supernova rates for 0.4 ≤ z &lt; 2.9 were calculated, and found to be in good agreement with previous estimates and predictions from cosmic star formation history. During the survey, two Type Ia supernovae in A1689 cluster members were also discovered, which allowed the Type Ia explosion rate in galaxy clusters to be estimated. Furthermore, the expectations of finding lensed supernovae at high redshift in simulated search campaigns that can be conducted with upcoming ground- and space-based telescopes, are discussed. Magnification from a galaxy lens also allows for detailed studies of the supernova properties at high redshift that otherwise would not be possible. Spectroscopic observations of lensed high-redshift supernovae Type Ia are of special interest since they can be used to test for evolution of the standard candle nature of these objects. If systematic redshift-dependent properties are found, their utility for future surveys could be challenged. In the thesis it is shown that the strongly lensed and very distant supernova Type Ia PS1-10afx at z=1.4, does not deviate from the well-studied nearby and intermediate populations of normal supernovae Type Ia. In a different study, the discovery of the first resolved multiply-imaged gravitationally lensed supernova Type Ia is also reported. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>

We present a detailed, multi-wavelength study of star formation (SF) and active galactic nucleus (AGN) activity in 11 near-infrared (IR) selected, spectroscopically confirmed massive (greater than or similar to 10(14)M(circle dot)) galaxy clusters at 1 < z < 1.75. Using new deep Herschel/PACS imaging, we characterize the optical to far-IR spectral energy distributions (SEDs) for IR-luminous cluster galaxies, finding that they can, on average, be well described by field galaxy templates. Identification and decomposition of AGNs through SED fittings allows us to include the contribution to cluster SF from AGN host galaxies. We quantify the star-forming fraction, dust-obscured SF rates (SFRs) and specific SFRs for cluster galaxies as a function of cluster-centric radius and redshift. In good agreement with previous studies, we find that SF in cluster galaxies at z greater than or similar to 1.4 is largely consistent with field galaxies at similar epochs, indicating an era before significant quenching in the cluster cores (r < 0.5 Mpc). This is followed by a transition to lower SF activity as environmental quenching dominates by z similar to 1. Enhanced SFRs are found in lower mass (10.1< logM(kappa)/M-circle dot < 10.8) cluster galaxies. We find significant variation in SF from cluster to cluster within our uniformly selected sample, indicating that caution should be taken when evaluating individual clusters. We examine AGNs in clusters from z = 0.5-2, finding an excess AGN fraction at z greater than or similar to 1, suggesting environmental triggering of AGNs during this epoch. We argue that our results-a transition from field-like to quenched SF, enhanced SF in lower mass galaxies in the cluster cores, and excess AGNs-are consistent with a co-evolution between SF and AGNs in clusters and an increased merger rate in massive halos at high redshift.

The centre of the Milky Way, commonly referred to as the Galactic Centre, is roughly that region within 500 pc of the central black hole, Sagittarius A*. Within the innermost parsec around the supermassive black hole Sagittarius A* are more than a hundred massive young stars whose orbits align to form one or possibly two discs. At about 100 pc is a ring containing more than ten million solar masses of molecular gas which could be the origin of some of the most massive star clusters in the Galaxy. I have performed a number of numerical simulations to help us understand how it is that these structures may have been formed. I firstly describe and test an improvement to the smoothed particle hydrodynamics code I used. This improves conservation of energy and momentum in certain situations such as in strong shocks from supernovae, which were to be included in a later chapter. The discs of massive stars around Sagittarius A* are believed to have been born there within fragmenting gaseous discs. This is problematic, as the formation of two stellar discs would require two gaseous counterparts. A method is described of forming multiple discs around a black hole from a single cloud's infall and subsequent tidal destruction. This is due to its prolate shape providing a naturally large distribution in the direction of the angular momentum vectors within the cloud. The resulting discs may then go on to form stars. Energetically, it would appear that a sequence of supernovae could potentially cause a giant molecular cloud to fall inwards towards the central black hole from an originally large orbit around the Galactic Centre. I simulate the impact on a giant molecular cloud of supernovae originating from a massive stellar cluster located a parsec away. Ultimately, the supernovae are found to have little effect. Finally, I simulate the formation of the dense ring of clouds observed in the Central Molec- ular Zone at a distance of about 100 pc from Sgr A*. Infalling gas is shown to be subject to such extreme tidal forces that a single cloud of gas is extended to form a long stream. The ribbon grows to the point that it self-intersects and forms a ring-like structure. Its complexity depends on the orbit of the original cloud. The position-velocity data is compared with observations, and similarities are noted.

This thesis investigates the political career of Stephen Dorsey, an Ohio industrialist who moved to Arkansas in 1871. Dorsey was elected to the U.S. Senate from Arkansas in 1873, served as secretary of the Republican National Committee for. the election of 1880, and was tried twice, in 1882 and 1883, for the Star Route postal frauds. Although Dorsey was acquitted, the Star Route frauds ended his political career. Separate chapters treat each phase of Dorsey's career. Major sources included the D41 Arkansas Gazette, the Congressional Record, the Garfield Papers, and the official transcripts of the Star Route trials. The thesis concludes that Dorsey's career was, the product of Ulysses S. Grant's influence within the Republican party in. the Gilded Age.

This study traces the history of the Plano Star-Courier. Information was obtained from newspaper files, interviews, and directories. The thesis is divided into six chapters: Chapter I introduces the study; Chapter II chronicles the founding of Plano and the first newspaper publications; Chapter III concerns consolidation of the newspapers in Plano; Chapter IV traces the changes in ownership; Chapter V describes the newspaper under family ownership and corporation ownership; Chapter VI summarizes the history, influence, and future of the Star-Courier. This thesis combines the history of the Plano Star- Courier and the previously unwritten history of the town. For 100 years, the Star-Courier reflected the attitudes, values, and needs of people in the community.

El presente estudio, de tipo cuasi experimental longitudinal y ciego, tuvo por objetivo determinar si el SEBT aplicado como método de entrenamiento de equilibrio dinámico e indirectamente de propiocepción, producía un efecto favorable en ésta, en sujetos entre 18 y 30 años que realizan actividad física y presenten inestabilidad funcional de tobillo.

High-pressure solution behavior such as density and phase behavior is a critical fundamental property for the design and optimization of various chemical processes, such as distillation and extraction in the production and purification of oils, polymers, and other natural materials. In this PhD study, solution behavior data are experimentally determined and equation of state (EoS) modeled for n-hexadecane, n-octadecane, n-eicosane, methylcyclohexane, ethylcyclohexane, cis-1,2-dimethylcyclohexane, cis-1,4-dimethylcyclohexane, trans-1,4-dimethylcyclohexane, o-xylene, m-xylene, p-xylene, and 2-methylnaphthalene at temperatures to 525 K and pressures to 275 MPa. A variable-volume view cell coupled with a linear variable differential transformer is used for the high-pressure determination. The reported density data are less than 0.4% of available literature data, which is within the estimated accumulated experimental uncertainty, 0.75%. Special attention is paid to the effect of architectural differences on the resultant high-pressure solution behavior. The reported data of low molecular weight hydrocarbons are modeled with Peng-Robinson (PR) equation of state (EoS), high-temperature high-pressure volume-translated cubic (HTHP VT-cubic) EoS, and perturbed-chain statistical fluid theory (PC-SAFT) EoS. The three pure-component parameters in PC-SAFT EoS can be either obtained from literature or from a group contribution (GC) method. Generally, PR EoS gives the worst predictions and HTHP VT-cubic EoS provides modest improvements over the PR EoS, but both of the equations underpredict the densities at high pressures. On the other hand, PC-SAFT EoS, with parameters from the literature or from a GC method, gives the improved density predictions with respect to PR EoS and HTHP VT-cubic EoS, although an overprediction of densities is found at high pressures. Model calculations also highlight the capability of these equations to account for the different densities observed for the hydrocarbon isomers. However, none of the EoS investigated in this study can fully account for the effect of isomeric structural differences on the high-pressure densities. For a better prediction of densities at high pressures, a new set of PC-SAFT pure-component parameters are obtained from a fit of the experimental density data obtained in this study and the mean absolution percent deviation is within 0.4%. The experimental technique and PC-SAFT EoS modeling method are extended to a star polymer-propane mixture. Star polymers with a fixed number of arms have a globular structure that does not promote chain entanglements. Star polymers can be synthesized with a large number of functional groups that can be readily modified to adjust their physical properties for specific applications in the areas of catalysis, coatings, lubrication, and drug delivery. In this study, a star polymer with a divinylbenzene core and statistically random methacrylate copolymer arms is synthesized with reversible addition-fragmentation-transfer method and fractionated with supercritical carbon dioxide and propane to obtain fractions with low molecular weight polydispersity. The phase behavior and density behavior are experimentally determined in supercritical propane for fractionated star polymers and the corresponding linear copolymer arms at temperatures to 423 K and pressures to 210 MPa. Experimental data are presented on the impact of the molecular weight, the backbone composition of the lauryl and methylmethacrylate repeat units in the copolymer arms, and the DVB core on the polymer-propane solution behavior. The star polymer is significantly more soluble due to its unique structure compared with the solubility of the linear copolymer arms in propane. The resultant phase behavior for the two homopolymers and the copolymers in propane are modeled using the PC-SAFT and copolymer PC-SAFT EoS, which give reasonable predictions for both phase behavior and density behavior. Model calculations are not presented for the phase behavior of the star polymers in propane since the PC-SAFT approach is not applicable for star polymer structures.

We study the properties of the foreground galaxy of the Ruby, the brightest gravitationally lensed high-redshift galaxy on the sub-millimeter sky as probed by the Planck satellite, and part of our sample of Planck's dusty GEMS. The Ruby consists of an Einstein ring of 1.4" diameter at z = 3.005 observed with ALMA at 0.1" resolution, centered on a faint, red, massive lensing galaxy seen with HST/WFC3, which itself has an exceptionally high redshift, z = 1.525 +/- 0.001, as confirmed with VLT/X-shooter spectroscopy. Here we focus on the properties of the lens and the lensing model obtained with LENSTOOL. The rest-frame optical morphology of this system is strongly dominated by the lens, while the Ruby itself is highly obscured, and contributes less than 10% to the photometry out to the K band. The foreground galaxy has a lensing mass of (3.70 +/- 0.35) x 10(11) M-Theta Magnification factors are between 7 and 38 for individual clumps forming two image families along the Einstein ring. We present a decomposition of the foreground and background sources in the WFC3 images, and stellar population synthesis modeling with a range of star-formation histories for Chabrier and Salpeter initial mass functions (IMFs). Only the stellar mass range obtained with the latter agrees well with the lensing mass. This is consistent with the bottom-heavy IMFs of massive high-redshift galaxies expected from detailed studies of the stellar masses and mass profiles of their low-redshift descendants, and from models of turbulent gas fragmentation. This may be the first direct constraint on the IMF in a lens at z = 1.5, which is not a cluster central galaxy.

We report the first detailed chemical abundance analysis of the exoplanet-hosting M-dwarf stars Kepler-138 and Kepler-186 from the analysis of high-resolution (R similar to 22,500) H-band spectra from the SDSS-IV-APOGEE survey. Chemical abundances of 13 elements-C, O, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, and Fe-are extracted from the APOGEE spectra of these early M-dwarfs via spectrum syntheses computed with an improved line list that takes into account H2O and FeH lines. This paper demonstrates that APOGEE spectra can be analyzed to determine detailed chemical compositions of M-dwarfs. Both exoplanet-hosting M-dwarfs display modest sub-solar metallicities: [Fe/H](Kepler-138) = -0.09 +/- 0.09 dex and [Fe/H](Kepler-186) = -0.08 +/- 0.10 dex. The measured metallicities resulting from this high-resolution analysis are found to be higher by similar to 0.1-0.2 dex than previous estimates from lower-resolution spectra. The C/O ratios obtained for the two planet-hosting stars are near-solar, with values of 0.55 +/- 0.10 for Kepler-138 and 0.52 +/- 0.12 for Kepler-186. Kepler-186 exhibits a marginally enhanced [Si/Fe] ratio.