VEINS: Inverted Echo Sounders in the Denmark Strait, as part of, FS "Poseidon" Cruise 222/1, August 5, 1996 - August 12, 1996

The overflow of cold dense water from the Denmark Strait is one of the key elements of the North Atlantic thermohaline circulation and has important consequences for global climate change. It is important to measure the transport of this water and to understand its variability on seasonal and longer time scales. The european funded project "Variability of Exchanges in Northern Seas" (VEINS MAS3CT960070) is an attempt to measure variations in the Arctic circulation using modern oceanographic instrumentation. An Inverted Echo Sounder and Bottom Pressure Recorder were successfully deployed to measure the thickness of this cold dense water and thus determine transport

Is the distant globular cluster Pal 14 in a deep-freeze?

We investigate the velocity dispersion of Pal 14, an outer Milky-Way globular cluster at Galactocentric distance of 71 kpc with a very low stellar density (central density 0.1-0.2 Msun/pc^3). Due to this low stellar density the binary population of Pal 14 is likely to be close to the primordial binary population. Artificial clusters are generated with the observed properties of Pal 14 and the velocity dispersion within these clusters is measured as Jordi et al. (2009) have done with 17 observed stars of Pal 14. We discuss the effect of the binary population on these measurements and find that the small velocity dispersion of 0.38 km/s which has been found by Jordi et al. (2009) would imply a binary fraction of less than 0.1, even though from the stellar density of Pal 14 we would expect a binary fraction of more than 0.5. We also discuss the effect of mass segregation on the velocity dispersion as possible explanation for this discrepancy, but find that it would increase the velocity dispersion further. Thus, either Pal 14 has a very unusual stellar population and its birth process was significantly different than we see in today's star forming regions, or the binary population is regular and we would have to correct the observed 0.38 km/s for binarity. In this case the true velocity dispersion of Pal 14 would be much smaller than this value and the cluster would have to be considered as "kinematically frigid", thereby possibly posing a challenge for Newtonian dynamics but in the opposite sense to MOND.Comment: 8 pages, 4 figures, accepted for publication in Ap

Improved Searches for HI in Three Dwarf Spheroidal Galaxies

Previous searches for HI in our Galaxy's dwarf spheroidal companions have not been complete enough to settle the question of whether or not these galaxies have HI, especially in their outer parts. We present VLA observations of three dwarf spheroidals: Fornax, Leo II, and Draco, all of which have known stellar velocities. The new data show no HI emission or absorption. Column density limits in emission are 4--7 x 10^18 atoms/cm^2 in the centers of the galaxies. The importance of the new observations is that they cover larger areas than previous searches and they are less plagued by confusion with foreground (Galactic) HI. The apparent absence of neutral gas in the Fornax dwarf spheroidal is especially puzzling because recent photometry shows evidence of stars only 10^8 years old. We discuss whether the VLA observations could have missed significant amounts of HI.Comment: 20 pages, 7 figures; to appear in the Astronomical Journa

The Velocity Dispersion Profile of the Remote Dwarf Spheroidal Galaxy Leo I: A Tidal Hit and Run?

(abridged) We present kinematic results for a sample of 387 stars located near Leo I based on spectra obtained with the MMT's Hectochelle spectrograph near the MgI/Mgb lines. We estimate the mean velocity error of our sample to be 2.4 km/s, with a systematic error of < 1 km/s. We produce a final sample of 328 Leo I red giant members, from which we measure a mean heliocentric radial velocity of 282.9 +/- 0.5 km/s, and a mean radial velocity dispersion of 9.2 +/- 0.4 km/s for Leo I. The dispersion profile of Leo I is flat out to beyond its classical `tidal' radius. We fit the profile to a variety of equilibrium dynamical models and can strongly rule out models where mass follows light. Two-component Sersic+NFW models with tangentially anisotropic velocity distributions fit the dispersion profile well, with isotropic models ruled out at a 95% confidence level. The mass and V-band mass-to-light ratio of Leo I estimated from equilibrium models are in the ranges 5-7 x 10^7 M_sun and 9-14 (solar units), respectively, out to 1 kpc from the galaxy center. Leo I members located outside a `break radius' (about 400 arcsec = 500 pc) exhibit significant velocity anisotropy, whereas stars interior appear to have isotropic kinematics. We propose the break radius represents the location of the tidal radius of Leo I at perigalacticon of a highly elliptical orbit. Our scenario can account for the complex star formation history of Leo I, the presence of population segregation within the galaxy, and Leo I's large outward velocity from the Milky Way. The lack of extended tidal arms in Leo I suggests the galaxy has experienced only one perigalactic passage with the Milky Way, implying that Leo I may have been injected into its present orbit by a third body a few Gyr before perigalacticon.Comment: ApJ accepted, 23 figures, access paper as a pdf file at http://www.astro.lsa.umich.edu/~mmateo/research.htm

Temperature and Kinematics of CIV Absorption Systems

We use Keck HIRES spectra of three intermediate redshift QSOs to study the physical state and kinematics of the individual components of CIV selected heavy element absorption systems. Fewer than 8 % of all CIV lines with column densities greater than 10^{12.5} cm^{-2} have Doppler parameters b < 6 km/s. A formal decomposition into thermal and non-thermal motion using the simultaneous presence of SiIV gives a mean thermal Doppler parameter b_{therm}(CIV) = 7.2 km/s, corresponding to a temperature of 38,000 K although temperatures possibly in excess of 300,000 K occur occasionally. We also find tentative evidence for a mild increase of temperature with HI column density. Non-thermal motions within components are typically small (< 10 km/s) for most systems, indicative of a quiescent environment. The two-point correlation function (TPCF) of CIV systems on scales up to 500 km/s suggests that there is more than one source of velocity dispersion. The shape of the TPCF can be understood if the CIV systems are caused by ensembles of objects with the kinematics of dwarf galaxies on a small scale, while following the Hubble flow on a larger scale. Individual high redshift CIV components may be the building blocks of future normal galaxies in a hierarchical structure formation scenario.Comment: submitted to the ApJ Letters, March 16, 1996 (in press); (13 Latex pages, 4 Postscript figures, and psfig.sty included

Validation of Computational Models of Auxiliary Ventilation Systems with Experimental Data

This paper reports the interim findings of a research program whose objective is to determine whether Computational Fluid Dynamic (CFD) models can be employed to accurately predict the airflow patterns within rapid development headings. In particular, the project aims to investigate the optimum set back distances for the ducts in order to adequately ventilate the face of the drivage. To validate the accuracy of the CFD model simulations measurements were obtained from a series of experiments performed on both scale models and within a full-scale surface gallery. The experimental scale-modeling program included making a series of pressure measurements across the face of the model for equivalent forcing duct setback distances of 5, 10 and 15 m (16, 33 and 50 ft). This pressure data was then plotted as contour plots and compared with the corresponding CFD predictions. A series of full-scale auxiliary ventilation trials were performed within a modified surface gallery. Three-dimensional velocity measurements were taken across a number of cross-sections using an ultrasonic anemometer. Velocity measurements were obtained for three forcing duct setback distances and for a typical force-exhaust overlap configuration

The Papers of Henry Clay. Volume 1. The Rising Statesman, 1797-1814

Henry Clay’s career spanned a half century of a great formative period in American history. The Papers of Henry Clay span the crucial first half of the nineteenth century in American history. Few men in his time were so intimately concerned with the formation of national policy, and few influenced so profoundly the growth of American political institutions. This compilation of ten volumes includes Clay’s letters, letters to Clay, his speeches, and other documents identified as his personal composition. Publication of this book was assisted by a grant from the National Historical Publications and Records Commission.https://uknowledge.uky.edu/upk_political_science_papers/1000/thumbnail.jp

Inverted Echo Sounders in the Denmark Strait, as part of FS Poseidon 290 [POS290], June 6, 2002 – June 24, 2002

The overflow of cold dense water from the Denmark Strait is one of the key elements of the north Atlantic thermohaline circulation and has important consequences for global climate change. It is important to measure the transport of this water and to understand its variability on seasonal and at longer time scales. The European funded project "Variability of Exchanges in Northern Seas" (VEINS MAS3CT960070) was an attempt to measure variations in the Arctic circulation using modern oceanographic instrumentation. The current program is a continuation of this research and may contribute to a proposed new program, Arctic Sub-Arctic Ocean Fluxes (ASOF). A combined Inverted Echo Sounder and Bottom Pressure Recorder was successfully recovered and re-deployed in the Denmark Strait to measure the thickness of this cold dense water and thus determine transport

Ecology and physiology of photosynthetic organisms in highly acid streams

Two surveys of the water chemistry and photosynthetic flora were carried out in England, for waters with a pH of 3.0 or less. Of the 16 sites located, fourteen were associated with coal mining, one with a barytes mine and one with an industrial effluent. One coal mining site (Site 16) and the industrial effluent (Site 15), were found to run intermittently below pH 3.0. Samples collected from 95 10 m reaches, showed that the waters were characterized by high levels of heavy metals, silicate and sulphate and that most carried moderately large levels of phosphate and combined inorganic nitrogen. The total flora from the 16 sites consisted of 24 algal species, two mosses and two flowering plants. Of the 8 species which occurred in over 20% of the roaches sampled, Euglena mutabilis was the most widespread and abundant species. One stream with a pH gradient of 2.6 - 7.0 (Brandon Pithouse Acid Stream) was studied in greater detail. Observations were made in respect to seasonal variation and to changes in chemistry and flora along the pH gradient. In addition, monthly estimations of the maximum standing crop of algae and moss protonema were carried out for one year. Analysis of these data suggests that over a large pH range, H+ concentration has the greatest influence on the number of species present in the stream; although other factors (eg. precipitation of ferric hydroxide) may also affect the presence and abundance of some algae. in addition to field studies, laboratory experiments were conducted on five species of algae isolated from Brandon Pithouse Acid Stream. These included an examination Of the effect pH had on growth and morphology and also the relationship between low pH and heavy metal toxicity