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Sample records for heino mller kaljo

  1. Masquerading as a Merger

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-11-01

    Dual active galactic nuclei (AGN), an intermediary product of galaxy mergers, can give us a better understanding of what happens when two galaxies collide. But because the angular separation of the two galactic nuclei is so small at this stage, identifying these systems is very difficult. In a recent study, a team of authors proposes a new technique for confirming dual AGN candidates.Signatures in SpectraTotal-intensity VLA image for J1023+3243. This system is confirmed as a dual AGN; the two compact radio cores are separately identifiable here. [Mller-Snchez et al. 2015]One approach commonly used to identify dual AGN candidates is to look for signatures in the spectra of these galaxies. Light is emitted by ionized gas in the narrow-line region (NLR), the region that extends from a few hundreds of parsecs to ~30kpc from the nuclei. The spatially-averaged spectrum of this region for dual AGN, however, appears double-peaked due to the motion of the two nuclei rotating around each other.But theres a problem with using this technique to identify dual AGN: other processes also produce double-peaked narrow-line emission, mimicking the behavior of dual AGN. These processes include the rotation of ionized gas in the galactic disk, and the motion of radio jets emitted from the AGN.A team of scientists led by Francisco Mller-Snchez (University of Colorado Boulder) have proposed that the use of a combination of high-resolution radio observations and spatially-resolved spectroscopy could be used to discern between these possible cases.Dual AGN or Moving Gas?To test this method, the group examined a sample of 18 active galactic nuclei from the Sloan Digital Sky Survey. These AGN had previously been identified as candidate dual AGN with double-peaked narrow emission lines. The team obtained both optical long-slit spectroscopy and high-resolution Very Large Array observations of these AGN. They then combined this information to identify the cause of the double-peaked lines in

  2. The Equations of Oceanic Motions

    NASA Astrophysics Data System (ADS)

    Müller, Peter

    2006-10-01

    Modeling and prediction of oceanographic phenomena and climate is based on the integration of dynamic equations. The Equations of Oceanic Motions derives and systematically classifies the most common dynamic equations used in physical oceanography, from large scale thermohaline circulations to those governing small scale motions and turbulence. After establishing the basic dynamical equations that describe all oceanic motions, M|ller then derives approximate equations, emphasizing the assumptions made and physical processes eliminated. He distinguishes between geometric, thermodynamic and dynamic approximations and between the acoustic, gravity, vortical and temperature-salinity modes of motion. Basic concepts and formulae of equilibrium thermodynamics, vector and tensor calculus, curvilinear coordinate systems, and the kinematics of fluid motion and wave propagation are covered in appendices. Providing the basic theoretical background for graduate students and researchers of physical oceanography and climate science, this book will serve as both a comprehensive text and an essential reference.

  3. Proposed stratotype for the base of the highest Cambrian stage at the first appearance datum of Cordylodus andresi, Lawson Cove section, Utah, USA

    USGS Publications Warehouse

    Miller, J.F.; Ethington, Raymond L.; Evans, K.R.; Holmer, L.E.; Loch, James D.; Popov, L.E.; Repetski, J.E.; Ripperdan, R.L.; Taylor, John F.

    2006-01-01

    We propose a candidate for the Global Standard Stratotype-section and Point (GSSP) for the base of the highest stage of the Furongian Series of the Cambrian System. The section is at Lawson Cove in the Ibex area of Millard County, Utah, USA. The marker horizon is the first appearance datum (FAD) of the conodont Cordylodus andresi Viira et Sergeyeva in Kaljo et al. [Kaljo, D., Borovko, N., Heinsalu, H., Khazanovich, K., Mens, K., Popov, L., Sergeyeva, S., Sobolevskaya, R., Viira, V., 1986. The Cambrian-Ordovician boundary in the Baltic-Ladoga clint area (North Estonia and Leningrad Region, USSR). Eesti NSV Teaduste Akadeemia Toimetised. Geologia 35, 97-108]. At this section and elsewhere this horizon also is the FAD of the trilobite Eurekia apopsis (Winston et Nicholls, 1967). This conodont characterizes the base of the Cordylodus proavus Zone, which has been recognized in many parts of the world. This trilobite characterizes the base of the Eurekia apopsis Zone, which has been recognized in many parts of North America. The proposed boundary is 46.7 m above the base of the Lava Dam Member of the Notch Peak Formation at the Lawson Cove section. Brachiopods, sequence stratigraphy, and carbon-isotope geochemistry are other tools that characterize this horizon and allow it to be recognized in other areas. ?? 2006 Nanjing Institute of Geology and Palaeontology, CAS.

  4. Frequency dependence 3.0: an attempt at codifying the evolutionary ecology perspective.

    PubMed

    Metz, Johan A J; Geritz, Stefan A H

    2016-03-01

    The fitness concept and perforce the definition of frequency independent fitnesses from population genetics is closely tied to discrete time population models with non-overlapping generations. Evolutionary ecologists generally focus on trait evolution through repeated mutant substitutions in populations with complicated life histories. This goes with using the per capita invasion speed of mutants as their fitness. In this paper we develop a concept of frequency independence that attempts to capture the practical use of the term by ecologists, which although inspired by population genetics rarely fits its strict definition. We propose to call the invasion fitnesses of an eco-evolutionary model frequency independent when the phenotypes can be ranked by competitive strength, measured by who can invade whom. This is equivalent to the absence of weak priority effects, protected dimorphisms and rock-scissor-paper configurations. Our concept differs from that of Heino et al. (TREE 13:367-370, 1998) in that it is based only on the signs of the invasion fitnesses, whereas Heino et al. based their definitions on the structure of the feedback environment, summarising the effect of all direct and indirect interactions between individuals on fitness. As it turns out, according to our new definition an eco-evolutionary model has frequency independent fitnesses if and only if the effect of the feedback environment on the fitness signs can be summarised by a single scalar with monotonic effect. This may be compared with Heino et al.'s concept of trivial frequency dependence defined by the environmental feedback influencing fitness, and not just its sign, in a scalar manner, without any monotonicity restriction. As it turns out, absence of the latter restriction leaves room for rock-scissor-paper configurations. Since in 'realistic' (as opposed to toy) models frequency independence is exceedingly rare, we also define a concept of weak frequency dependence, which can be interpreted

  5. Effects of Noninvasive Ventilation on Sleep Outcomes in Amyotrophic Lateral Sclerosis

    PubMed Central

    Katzberg, Hans D.; Selegiman, Adam; Guion, Lee; Yuan, Nancy; Cho, Sungho C.; Katz, Jonathan S.; Miller, Robert G.; So, Yuen T.

    2013-01-01

    Study Objectives: The objective was to study the effects on noninvasive ventilation on sleep outcomes in patient with ALS, specifically oxygenation and overall sleep quality. Methods: Patients with ALS who met criteria for initiation of NIV were studied with a series of 2 home PSG studies, one without NIV and a follow-up study while using NIV. Primary outcome was a change in the maximum overnight oxygen saturation; secondary outcomes included change in mean overnight oxygen saturation, apnea and hypopnea indexes, sleep latency, sleep efficiency, sleep arousals, and sleep architecture. Results: A total of 94 patients with ALS were screened for eligibility; 15 were enrolled; and 12 completed study procedures. Maximum overnight oxygen saturation improved by 7.0% (p = 0.01) and by 6.7% during REM sleep (p = 0.02) with NIV. Time spent below 90% oxygen saturation was also significant-ly better with NIV (30% vs 19%, p < 0.01), and there was trend for improvement in mean overnight saturation (1.5%, p = 0.06). Apnea index (3.7 to 0.7), hypopnea index (6.2 to 5.7), and apnea hypopnea index (9.8 to 6.3) did not significantly improve after introducing NIV. NIV had no effect on sleep efficiency (mean change 10%), arousal index (7 to 12), or sleep stage distribution (Friedman chi-squared = 0.40). Conclusions: NIV improved oxygenation but showed no significant effects on sleep efficiency, sleep arousals, restful sleep, or sleep architecture. The net impact of these changes for patients deserves further study in a larger group of ALS patients. Citation: Katzberg HD; Selegiman A; Guion L; Yuan N; Cho SC; Katz JS; Mller RG; So YT. Effects of noninvasive ventilation on sleep outcomes in amyotrophic lateral sclerosis. J Clin Sleep Med 2013;9(4):345-351. PMID:23585750

  6. "Computational Modeling of Actinide Complexes"

    SciTech Connect

    Balasubramanian, K

    2007-03-07

    We will present our recent studies on computational actinide chemistry of complexes which are not only interesting from the standpoint of actinide coordination chemistry but also of relevance to environmental management of high-level nuclear wastes. We will be discussing our recent collaborative efforts with Professor Heino Nitsche of LBNL whose research group has been actively carrying out experimental studies on these species. Computations of actinide complexes are also quintessential to our understanding of the complexes found in geochemical, biochemical environments and actinide chemistry relevant to advanced nuclear systems. In particular we have been studying uranyl, plutonyl, and Cm(III) complexes are in aqueous solution. These studies are made with a variety of relativistic methods such as coupled cluster methods, DFT, and complete active space multi-configuration self-consistent-field (CASSCF) followed by large-scale CI computations and relativistic CI (RCI) computations up to 60 million configurations. Our computational studies on actinide complexes were motivated by ongoing EXAFS studies of speciated complexes in geo and biochemical environments carried out by Prof Heino Nitsche's group at Berkeley, Dr. David Clark at Los Alamos and Dr. Gibson's work on small actinide molecules at ORNL. The hydrolysis reactions of urnayl, neputyl and plutonyl complexes have received considerable attention due to their geochemical and biochemical importance but the results of free energies in solution and the mechanism of deprotonation have been topic of considerable uncertainty. We have computed deprotonating and migration of one water molecule from the first solvation shell to the second shell in UO{sub 2}(H{sub 2}O){sub 5}{sup 2+}, UO{sub 2}(H{sub 2}O){sub 5}{sup 2+}NpO{sub 2}(H{sub 2}O){sub 6}{sup +}, and PuO{sub 2}(H{sub 2}O){sub 5}{sup 2+} complexes. Our computed Gibbs free energy(7.27 kcal/m) in solution for the first time agrees with the experiment (7.1 kcal

  7. Are Heinrich events triggered by the ocean? From a conceptual model to a 3D ice sheet model

    NASA Astrophysics Data System (ADS)

    Alvarez-Solas, J.; Ritz, C.; Charbit, S.; Ramstein, G.; Paillard, D.; Dumas, C.

    2009-12-01

    A common explanation for Heinrich events consists in an internal thermomechanical feedback of the Northern Hemisphere ice sheets allowing the occurrence of periodical large ice surges into the ocean. It has been proposed that these large-scale surges likely occur when basal ice reaches the melting point in regions where subglacial sediment allows very strong sliding. Attempts to simulate such mechanism (so-called bing-purge) in the framework of the shallow ice approximation (SIA) indeed succeeded to produce oscillations (HEINO experiments). However these results are still controversial because the oscillation periods were very dependent on numerical methods and, more important, because the SIA does not take into account longitudinal stresses and is thus not suitable when there are strong gradient in velocity. Using a 3D ice sheet model, GRISLI, in which ice streams velocities are obtained with the MacAyeal equation and thus longitudinal stresses are accounted for, no oscillations can be obtained with only the ice sheet-ice stream system. The recent breakup of some ice shelves in Antarctica and the associated changes on ice streams velocities illustrates the importance of the buttressing effect on ice surges. We suggest here that ocean variability has to be considered as a potential triggering factor via the ice-shelf erosion and its consequences on ice streams. With a conceptual ice sheet /ice shelf /ocean model we demonstrate the ability of this simple model to produce physically based oscillations compatible with the signature of Heinrich events that can be only generated in presence of ocean millennial variability which is suggested by all the data available.

  8. Is mad cow disease caused by a bacteria?

    PubMed

    Broxmeyer, L

    2004-01-01

    Transmissible spongioform enchephalopathies (TSE's), include bovine spongiform encephalopathy (also called BSE or "mad cow disease"), Creutzfeldt-Jakob disease (CJD) in humans, and scrapie in sheep. They remain a mystery, their cause hotly debated. But between 1994 and 1996, 12 people in England came down with CJD, the human form of mad cow, and all had eaten beef from suspect cows. Current mad cow diagnosis lies solely in the detection of late appearing "prions", an acronym for hypothesized, gene-less, misfolded proteins, somehow claimed to cause the disease. Yet laboratory preparations of prions contain other things, which could include unidentified bacteria or viruses. Furthermore, the rigors of prion purification alone, might, in and of themselves, have killed the causative virus or bacteria. Therefore, even if samples appear to infect animals, it is impossible to prove that prions are causative. Manuelidis found viral-like particles, which even when separated from prions, were responsible for spongiform STE's. Subsequently, Lasmezas's study showed that 55% of mice injected with cattle BSE, and who came down with disease, had no detectable prions. Still, incredibly, prions, are held as existing TSE dogma and Heino Dringer, who did pioneer work on their nature, candidly predicts "it will turn out that the prion concept is wrong." Many animals that die of spongiform TSE's never show evidence of misfolded proteins, and Dr. Frank Bastian, of Tulane, an authority, thinks the disorder is caused by the bacterial DNA he found in this group of diseases. Recently, Roels and Walravens isolated Mycobacterium bovis it from the brain of a cow with the clinical and histopathological signs of mad cow. Moreover, epidemiologic maps of the origins and peak incidence of BSE in the UK, suggestively match those of England's areas of highest bovine tuberculosis, the Southwest, where Britain's mad cow epidemic began. The neurotoxic potential for cow tuberculosis was shown in pre-1960

  9. Super-Sharp Radio "Vision" Measures Galaxy's Motion in Space

    NASA Astrophysics Data System (ADS)

    2005-03-01

    Andreas Brunthaler of the Max Planck Institute for Radioastronomy in Bonn, Germany; Heino Falcke of ASTRON in the Netherlands; Lincoln Greenhill, also of the Harvard- Smithsonian Center for Astrophysics; and Christian Henkel, also of the Max Planck Institute in Bonn. The scientists reported their findings in the March 4 issue of the journal Science. The VLBA is a system of ten radio-telescope antennas, each with a dish 25 meters (82 feet) in diameter and weighing 240 tons. From Mauna Kea on the Big Island of Hawaii to St. Croix in the U.S. Virgin Islands, the VLBA spans more than 5,000 miles, providing astronomers with the sharpest vision of any telescope on Earth or in orbit. Dedicated in 1993, the VLBA has an ability to see fine detail equivalent to being able to stand in New York and read a newspaper in Los Angeles. The VLBA's scientific achievements include making the most accurate distance measurement ever made of an object beyond the Milky Way Galaxy; the first mapping of the magnetic field of a star other than the Sun; movies of motions in powerful cosmic jets and of distant supernova explosions; the first measurement of the propagation speed of gravity; and long-term measurements that have improved the reference frame used to map the Universe and detect tectonic motions of Earth's continents. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

  10. Radio Astronomers Lift "Fog" on Milky Way's Dark Heart: Black Hole Fits Inside Earth's Orbit

    NASA Astrophysics Data System (ADS)

    2004-04-01

    Thirty years after astronomers discovered the mysterious object at the exact center of our Milky Way Galaxy, an international team of scientists has finally succeeded in directly measuring the size of that object, which surrounds a black hole nearly four million times more massive than the Sun. This is the closest telescopic approach to a black hole so far and puts a major frontier of astrophysics within reach of future observations. The scientists used the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope to make the breakthrough. Milky Way Nucleus The Milky Way's nucleus, as seen with the VLA. Sagittarius A* is the bright white dot at center. CREDIT: NRAO/AUI/NSF, Jun-Hui Zhao, W.M. Goss (Click on Image for Larger Version) "This is a big step forward," said Geoffrey Bower, of the University of California-Berkeley. "This is something that people have wanted to do for 30 years," since the Galactic center object, called Sagittarius A* (pronounced "A-star"), was discovered in 1974. The astronomers reported their research in the April 1 edition of Science Express. "Now we have a size for the object, but the mystery about its exact nature still remains," Bower added. The next step, he explained, is to learn its shape, "so we can tell if it is jets, a thin disk, or a spherical cloud." The Milky Way's center, 26,000 light-years from Earth, is obscured by dust, so visible-light telescopes cannot study the object. While radio waves from the Galaxy's central region can penetrate the dust, they are scattered by turbulent charged plasma in the space along the line of sight to Earth. This scattering had frustrated earlier attempts to measure the size of the central object, just as fog blurs the glare of distant lighthouses. "After 30 years, radio telescopes finally have lifted the fog and we can see what is going on," said Heino Falcke, of the Westerbork Radio Observatory in the Netherlands, another member of the research team. The bright, radio