WorldWideScience

Sample records for early universe carbon

  1. CEMP stars: possible hosts to carbon planets in the early universe

    CERN Document Server

    Mashian, Natalie

    2016-01-01

    We explore the possibility of planet formation in the carbon-rich protoplanetary disks of carbon-enhanced metal-poor (CEMP) stars, possible relics of the early Universe. The chemically anomalous abundance patterns ([C/Fe] $\\geq$ 0.7) in this subset of low-mass stars suggest pollution by primordial core-collapsing supernovae (SNe) ejecta that are particularly rich in carbon dust grains. By comparing the dust-settling timescale in the protoplanetary disks of CEMP stars to the expected disk lifetime (assuming dissipation via photoevaporation), we determine the maximum distance $r_{max}$ from the host CEMP star at which carbon-rich planetesimal formation is possible, as a function of the host star's [C/H] abundance. We then use our linear relation between $r_{max}$ and [C/H], along with the theoretical mass-radius relation derived for a solid, pure carbon planet, to characterize potential planetary transits across host CEMP stars. Given that the related transits are detectable with current and upcoming space-base...

  2. The First Mass Function and Rise of Carbon in the Early Universe

    Science.gov (United States)

    Rasmussen, Kaitlin; Beers, Timothy C.; Placco, Vinicius M.; Yoon, Jinmi

    2017-01-01

    We investigate the impact of the First Mass Function (FMF) of stars on the distribution of stellar carbon abundances in the early Universe. We propose a picture that includes primary carbon production by the massive first-generation stars, recorded in the atmospheres of CEMP-no stars (which show no over-abundances of neutron-capture elements), and secondary carbon production by subsequent generations of AGB stars, recorded in the subset of mass-transfer binaries now observed as CEMP-$s$ stars (which exhibit strong over-abundances of neutron-capture elements).Recently, CEMP-no stars have been found to comprise separable populations within this category, distinguished by their light-element and iron-peak element abundances (Yoon et al. 2016, Placco et al. 2016). The existence of these populations can also be used to indirectly infer information about the FMF. Additionally, we investigate the contrasting behavior of CEMP stars with their more metal-rich counterparts, focusing on their kinematics, spatial distribution, and elemental abundances, in order to constrain the chemical-enrichment history of the Galaxy, from the earliest stars to the present.References:Placco, V.~M., et al. (2016), ApJ, in press (arXiv:1609.02134)Yoon, J., et al. (2016), ApJ, in press (arXiv:1607.06336)This work received partial support from PHY 14-30152; Physics FrontierCenter/JINA Center for the Evolution of the Elements (JINA-CEE), awardedby the US National Science Foundation.

  3. BD +44 493: A Ninth Magnitude Messenger from the Early Universe; Carbon Enhanced and Beryllium Poor

    CERN Document Server

    Ito, Hiroko; Honda, Satoshi; Beers, Timothy C

    2009-01-01

    We present a 1D LTE chemical abundance analysis of the very bright (V=9.1) Carbon-Enhanced Metal-Poor (CEMP) star BD +44 493, based on high-resolution, high signal-to-noise spectra obtained with Subaru/HDS. The star is shown to be a subgiant with an extremely low iron abundance ([Fe/H]=-3.7), while it is rich in C ([C/Fe]=+1.3) and O ([O/Fe]=+1.6). Although astronomers have been searching for extremely metal-poor stars for decades, this is the first star found with [Fe/H]<-3.5 and an apparent magnitude V<12. Based on its low abundances of neutron-capture elements (e.g., [Ba/Fe]=-0.59), BD +44 493 is classified as a "CEMP-no" star. Its abundance pattern implies that a first-generation faint supernova is the most likely origin of its carbon excess, while scenarios related to mass loss from rapidly-rotating massive stars or mass transfer from an AGB companion star are not favored. From a high-quality spectrum in the near-UV region, we set an very low upper limit on this star's beryllium abundance (A(Be)=lo...

  4. Gesturing in the early universities.

    Science.gov (United States)

    O'Boyle, C

    2000-01-01

    Research into the oral and literary traditions of scholastic education usually emphasizes the significance of the world in late medieval pedagogy. This paper suggests that coded hand signals provided early university scholars with an important non-verbal means of communication too. Using illustrations of classroom scenes from early university manuscripts, this paper analyzes the artistic conventions for representating gestures that these images embody. By building up a typology of these gesticulations, it demonstrates that the producers of these images and their audience shared a perception of scholastic education that embraced a sophisticated understanding of the activities associated with university education.

  5. Axions in the early Universe

    Energy Technology Data Exchange (ETDEWEB)

    Graf, Peter; Steffen, Frank Daniel [Max-Planck-Institut fuer Physik, Muenchen (Germany)

    2010-07-01

    The smallness of the CP violating term in the QCD Lagrangian is the well known strong CP problem. If it is solved via the Peccei-Quinn (PQ) mechanism, the pseudo-Nambu-Goldstone boson associated with the spontaneous breaking of the new chiral U(1){sub PQ} symmetry is the axion. We study the behavior of axions in the early Universe and calculate the temperature at which the axion decouples from the early QCD plasma.

  6. Water Emission from Early Universe

    Science.gov (United States)

    Jarugula, Sreevani; Vieira, Joaquin

    2017-06-01

    The study of dusty star forming galaxies (DSFGs) is important to understand galaxy assembly in early universe. A bulk of star formation at z ˜ 2-3 takes place in DSFGs but are obscured by dust in optical/UV. However, they are extremely bright in far infrared (FIR) and submillimeter with infrared luminosities of 10^{11} - 10^{13} L_{⊙}. ALMA, with its high spatial and spectral resolution, has opened up a new window to study molecular lines, which are vital to our understanding of the excitation and physical processes in the galaxy. Carbon monoxide (CO) being the second most abundant and bright molecule after hydrogen (H_{2}), is an important tracer of star forming potential. Besides CO, water (H_{2}O) is also abundant and it's line strength is comparable to high-J CO lines in high redshift Ultra Luminous Infrared Galaxies (ULIRGs). Studies have shown H_{2}O to directly trace the FIR field and hence the star forming regions. Moreover, L_{H_{2}O}/L_{IR} ratio is nearly constant for five of the most important water lines and does not depend on the presence of AGN implying that H_{2}O is one of the best tracers of star forming regions (SFRs). This incredible correlation holds for nearly five orders of magnitude in luminosity and observed in both local and high redshift luminous infrared galaxies. In this talk, I will discuss the importance of H_{2}O in tracing FIR field and show the preliminary results of resolved water emission from three high-redshift gravitationally lensed South Pole Telescope (SPT) sources obtained from ALMA cycle 3 and cycle 4. These sources are among the first H_{2}O observations with resolved spatial scales ˜ 1 kpc and will prove to be important for ALMA and galaxy evolution studies.

  7. Galaxies in the Early Universe

    DEFF Research Database (Denmark)

    Krogager, Jens-Kristian

    Understanding how galaxies evolved from the early Universe through cosmic time is a fundamental part of modern astrophysics. In order to study this evolution it is important to sample the galaxies at various times in a consistent way through time. In regular luminosity selected samples, our...

  8. Carbon in the Universe

    Science.gov (United States)

    Allamandola, Louis J.

    2013-01-01

    Over the past few decades, NASA missions have revealed that we live in a Universe that is not a hydrogen-dominated, physicist's paradise, but in a molecular Universe with complex molecules directly interwoven into its fabric. These missions have shown that molecules are an abundant and important component of astronomical objects at all stages of their evolution and that they play a key role in many processes that dominate the structure and evolution of galaxies. Closer to home in our galaxy, the Milky Way, they have revealed a unique and complex organic inventory of regions of star and planet formation that may well represent some of the prebiotic roots to life. Astrobiology emerges from the great interest in understanding astrochemical evolution from simple to complex molecules, especially those with biogenic potential and the roles they may play as primordial seeds in the origin of life on habitable worlds. The first part of this talk will highlight how infrared spectroscopic studies of interstellar space, combined with dedicated laboratory simulations, have revealed the widespread presence of complex organics across deep space. The remainder of the presentation will focus on the evolution of these materials and astrobiology.

  9. Shocks in the Early Universe.

    Science.gov (United States)

    Pen, Ue-Li; Turok, Neil

    2016-09-23

    We point out a surprising consequence of the usually assumed initial conditions for cosmological perturbations. Namely, a spectrum of Gaussian, linear, adiabatic, scalar, growing mode perturbations not only creates acoustic oscillations of the kind observed on very large scales today, it also leads to the production of shocks in the radiation fluid of the very early Universe. Shocks cause departures from local thermal equilibrium as well as create vorticity and gravitational waves. For a scale-invariant spectrum and standard model physics, shocks form for temperatures 1  GeVUniverse as early as 10^{-30}  sec after the big bang.

  10. Planets in the Early Universe

    CERN Document Server

    Shchekinov, Yu A; Murthy, J

    2012-01-01

    Several planets have recently been discovered around old and metal-poor stars, implying that the planets are also old, formed in the early universe. The canonical theory suggests that the conditions for their formation could not have existed at such early epochs. The required conditions such as sufficiently high dust-to-gas ratio, could in fact have existed in the early universe immediately following the first episode of metal production. Metal-rich regions may have existed in multiple isolated pockets of enriched and weakly-mixed gas close to the massive stars. Observations of quasars and gamma-ray bursts show a very wide spread of metals in absorption from $\\rm [X/H] \\simeq -3$ to $\\simeq -0.5$. This suggests that physical conditions in the metal-abundant clumps could have been similar to where protoplanets form today. However, planets could have formed even in low-metallicity environments, where formation of stars is expected to proceed at higher densities. In such cases, the circumstellar accretion disks ...

  11. Shocks in the Early Universe

    CERN Document Server

    Pen, Ue-Li

    2015-01-01

    We point out a surprising consequence of the usually assumed initial conditions for cosmological perturbations. Namely, a scale-invariant spectrum of Gaussian, linear, adiabatic, scalar, growing mode perturbations not only creates acoustic oscillations, of the kind observed in great detail on large scales today, it also leads to the production of shock waves in the radiation fluid of the very early universe. At very early epochs, $1$ GeV$

  12. Cosmology and the early universe

    Science.gov (United States)

    Joshi, Abhigna

    2017-01-01

    In the beginning the universe was in a hot dense state nearly 13.8 billion years ago. The thermal history of the universe was traced back to an era when the temperature was about 1012K. At this early time, the universe was filled with particles-mostly photons and leptons- whose interactions are hopefully weak enough to allow this medium to be treated as a more or less ideal gas. However, if we look back a little further, into the first 0.0001 second of cosmic history when the temperature was above 1012K. At such temperatures, there will be present in thermal equilibrium copious numbers of strongly interacting particles-mostly masons and baryons-with a mean interparticle distance less than a Compton wavelength. These particles will be in a state of continual mutual interaction, and cannot reasonably be expected to obey any simple equation of state. The inflationary epoch lasted from 10-36seconds after the Big Bang to sometime between 10-33and 10-32seconds. Matter and energy created in this time. Right after that space expanded exponentially with enormous rate of 74.3 +/-2.1Km per second per Mpc. Undergraduate student and researcher of the string theory, quantum gravity, cosmology and quantum biology.

  13. Noncommutativity in the early universe

    Science.gov (United States)

    Oliveira-Neto, G.; Silva de Oliveira, M.; Monerat, G. A.; Corrêa Silva, E. V.

    In the present work, we study the noncommutative version of a quantum cosmology model. The model has a Friedmann-Robertson-Walker (FRW) geometry, the matter content is a radiative perfect fluid and the spatial sections have zero constant curvature. In this model, the scale factor takes values in a bounded domain. Therefore, its quantum mechanical version has a discrete energy spectrum. We compute the discrete energy spectrum and the corresponding eigenfunctions. The energies depend on a noncommutative parameter β. We compute the scale factor expected value () for several values of β. For all of them, oscillates between maxima and minima values and never vanishes. It gives an initial indication that those models are free from singularities, at the quantum level. We improve this result by showing that if we subtract a quantity proportional to the standard deviation of a from , this quantity is still positive. The behavior, for the present model, is a drastic modification of the behavior in the corresponding commutative version of the present model. There, grows without limits with the time variable. Therefore, if the present model may represent the early stages of the universe, the results of the present paper give an indication that may have been, initially, bounded due to noncommutativity. We also compute the Bohmian trajectories for a, which are in accordance with , and the quantum potential Q. From Q, we may understand why that model is free from singularities, at the quantum level.

  14. The Early Universe in Loop Quantum Cosmology

    OpenAIRE

    Bojowald, M.

    2005-01-01

    Loop quantum cosmology applies techniques derived for a background independent quantization of general relativity to cosmological situations and draws conclusions for the very early universe. Direct implications for the singularity problem as well as phenomenology in the context of inflation or bouncing universes result, which will be reviewed here. The discussion focuses on recent new results for structure formation and generalizations of the methods.

  15. Predictors of Early Retirement Among University Faculty.

    Science.gov (United States)

    Monahan, Deborah J.; Greene, Vernon L.

    1987-01-01

    Interviews with faculty at a university having an incentive early retirement plan revealed that those choosing to retire early were in poorer health, faced smaller proportional income decrement upon retirement, were less satisfied with teaching assignments, and considered themselves lower in research productivity and higher in teaching and…

  16. WMAP - A Glimpse of the Early Universe

    Science.gov (United States)

    Wollack, Edward

    2009-01-01

    The early Universe was incredibly hot, dense, and homogeneous. A powerful probe of this time is provided by the relic radiation which we refer to today as the Cosmic Microwave Background (CMB). Images produced from this light contain the earliest glimpse of the Universe after the "Big Bang" and the signature of the evolution of its contents. By exploiting these clues, precise constraints on the age, mass density, and geometry of the early Universe can be derived. The history of this intriguing cosmological detective story will be reviewed. Recent results from NASA's Wilkinson Microwave Anisotropy Probe (WMAP) will be presented.

  17. Particle physics in the very early universe

    Science.gov (United States)

    Schramm, D. N.

    1981-01-01

    Events in the very early big bang universe in which elementary particle physics effects may have been dominant are discussed, with attention to the generation of a net baryon number by way of grand unification theory, and emphasis on the possible role of massive neutrinos in increasing current understanding of various cosmological properties and of the constraints placed on neutrino properties by cosmology. It is noted that when grand unification theories are used to describe very early universe interactions, an initially baryon-symmetrical universe can evolve a net baryon excess of 10 to the -9th to 10 to the -11th per photon, given reasonable parameters. If neutrinos have mass, the bulk of the mass of the universe may be in the form of leptons, implying that the form of matter most familiar to physical science may not be the dominant form of matter in the universe.

  18. Sterile neutrinos in the early universe

    Energy Technology Data Exchange (ETDEWEB)

    Malaney, R.A. (Lawrence Livermore National Lab., CA (USA)); Fuller, G.M. (California Univ., San Diego, La Jolla, CA (USA). Dept. of Physics)

    1990-11-14

    We discuss the role played by right-handed sterile neutrinos in the early universe. We show how well known {sup 4}He constraint on the number of relativistic degrees of freedom at early times limits the equilibration of the right handed neutrino sea with the background plasma. We discuss how this allows interesting constraints to be placed on neutrino properties. In particular, a new limit on the Dirac mass of the neutrino is presented. 12 refs.

  19. The Quantum Echo of the Early Universe

    CERN Document Server

    Blasco, Ana; Martin-Benito, Mercedes; Martin-Martinez, Eduardo

    2015-01-01

    We show that the fluctuations of quantum fields as seen by late comoving observers are significantly influenced by the history of the early Universe, and therefore they transmit information about the nature of spacetime in timescales when quantum gravitational effects were non-negligible. We discuss how this may be observable even nowadays, and thus used to build falsifiability tests of quantum gravity theories.

  20. WMAP - A Portrait of the Early Universe

    Science.gov (United States)

    Wollack, Edward J.

    2008-01-01

    A host of astrophysical observations suggest that early Universe was incredibly hot, dense, and homogeneous. A powerful probe of this time is provided by the relic radiation which we refer to today as the Cosmic Microwave Background (CMB). Images produced from this light contain the earliest glimpse of the Universe after the 'Big Bang' and the signature of the evolution of its contents. By exploiting these clues, constraints on the age, mass density, and geometry of the early Universe can be derived. A brief history of the evolution of the microwave radiometer systems and map making approaches used in advancing these aspects our understanding of cosmological will be reviewed. In addition, an overview of the results from NASA's Wilkinson Microwave Anisotropy (WMAP) will be presented.

  1. Bursts from the very early universe

    Energy Technology Data Exchange (ETDEWEB)

    Silk, J. [Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom); Stodolsky, L. [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Munich (Germany)]. E-mail: les@mppmu.mpg.de

    2006-07-27

    Bursts of weakly interacting particles such as neutrinos or even more weakly interacting particles such as wimps and gravitons from the very early universe would offer a much deeper 'look back time' to early epochs than is possible with photons. We consider some of the issues related to the existence of such bursts and their detectability. Characterizing the burst rate by a probability P per Hubble four-volume we find, for events in the radiation-dominated era, that the natural unit of description is the present intensity of the CMB times P. The existence of such bursts would make the observation of pheno associated with very early times in cosmology at least conceptually possible. One might even hope to probe the transplanckian epoch if complexes more weakly interacting than the graviton can exist. Other conceivable applications include the potential detectability of the formation of 'pocket universes' in a multiverse.

  2. Early Universes with Effective Discrete Time

    CERN Document Server

    Baulieu, Laurent

    2016-01-01

    The mechanism for triggering the universe inflation could be that at very early periods the time variable was discrete instead of smooth. Alternatively, and perhaps equivalently, it could be the consequence that the metrics of the early universe was a strongly concentrated gravitational coherent state with very high frequency oscillations, allowing local pair creations by a generalisation to gravity of the Schwinger mechanism, perhaps by creation of black holes of masses superior to the Planck scale. The lattice spacing between two clicks in the discrete time picture corresponds to the inverse frequency of the gravitational coherent state in the other picture. In both cases, a much lower time than the Planck time might represent a new fundamental scale, giving new type of physics. To make possible a concrete estimation of the pair production probability, we propose that the oscillating coherent state metrics that defines this very early geometry minimises the Einstein gravity action coupled to interacting 1-,...

  3. Discovery Mondays: The very early Universe

    CERN Multimedia

    2003-01-01

    Copyright NASARetracing the very early Universe to understand why there is "something rather than nothing" is one of the challenges facing astrophysics today. It is also the theme of the third Discovery Monday, to be held in the Microcosm on 7 July, where you will be welcomed by a number of scientists. A professional astronomer will allow you to look through his telescope and explain how it works. A cosmologist will talk to you about the very early Universe and a CERN physicist will show you how it's possible to trap antimatter. The mirror of matter, antimatter should have existed in the same quantities as matter in the very early stages of the Universe but today it seems to have virtually disappeared. Perhaps the research being done at CERN will one day explain how an infinitesimal predominance of matter over antimatter resulted in such a richly structured Universe. Come along to the Microcosm on Monday, 7 July between 7.30 p.m. and 9.00 p.m. Entrance is free http://www.cern.ch/microcosm N.B.: The Discove...

  4. String windings in the early universe

    CERN Document Server

    Easther, R; Jackson, M G; Kabat, D; Easther, Richard; Greene, Brian R.; Jackson, Mark G.; Kabat, Daniel

    2004-01-01

    We study string dynamics in the early universe. Our motivation is the proposal of Brandenberger and Vafa, that string winding modes may play a key role in decompactifying three spatial dimensions. We model the universe as a homogeneous but anisotropic 9-torus filled with a gas of excited strings. We adopt initial conditions which fix the dilaton and the volume of the torus, but otherwise assume all states are equally likely. We study the evolution of the system both analytically and numerically to determine the late-time behavior. We find that, although dynamical evolution can indeed lead to three large spatial dimensions, such an outcome is not statistically favored.

  5. Sterile Neutrinos in the Early Universe

    Energy Technology Data Exchange (ETDEWEB)

    Tamborra, Irene [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut) Föhringer Ring 6, 80805 München (Germany); Hannestad, Steen [Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C (Denmark); Tram, Thomas [Institut de Théorie des Phénomenènes Physiques, École Polytechnique Fédérale de Lausanne, 1015, Lausanne (Switzerland)

    2013-04-15

    Recent cosmological data favor additional relativistic degrees of freedom beyond the three active neutrinos and photons. Light sterile neutrinos are prime candidates for such additional radiation. However, constraints on sterile neutrinos based on the current cosmological data have been derived assuming that they are thermalized at the Big Bang Nucleosynthesis (BBN) epoch and such assumption is not justified a priori. We will discuss the evolution of light sterile neutrinos in the early universe and their thermalization just before BBN begins.

  6. QCD development in the early universe

    Energy Technology Data Exchange (ETDEWEB)

    Gromov, N. A., E-mail: gromov@dm.komisc.ru [Komi Science Center of the Ural Division of the Russian Academy of Sciences, Department of Mathematics (Russian Federation)

    2017-03-15

    The high-energy limit of Quantum Chromodynamics is generated by the contraction of its gauge groups. Contraction parameters are taken identical with those of the Electroweak Model and tend to zero when energy increases. At the infinite energy limit all quarks lose masses and have only one color degree of freedom. The limit model represents the development of Quantum Chromodynamics in the early Universe from the Big Bang up to the end of several milliseconds.

  7. Protostar formation in the early universe.

    Science.gov (United States)

    Yoshida, Naoki; Omukai, Kazuyuki; Hernquist, Lars

    2008-08-01

    The nature of the first generation of stars in the universe remains largely unknown. Observations imply the existence of massive primordial stars early in the history of the universe, and the standard theory for the growth of cosmic structure predicts that structures grow hierarchically through gravitational instability. We have developed an ab initio computer simulation of the formation of primordial stars that follows the relevant atomic and molecular processes in a primordial gas in an expanding universe. The results show that primeval density fluctuations left over from the Big Bang can drive the formation of a tiny protostar with a mass 1% that of the Sun. The protostar is a seed for the subsequent formation of a massive primordial star.

  8. Protostar Formation in the Early Universe

    CERN Document Server

    Yoshida, Naoki; Hernquist, Lars

    2008-01-01

    The nature of the first generation of stars in the Universe remains largely unknown. Observations imply the existence of massive primordial stars early in the history of the universe, and the standard theory for the growth of cosmic structure predicts that structures grow hierarchically through gravitational instability. We have developed an ab initio computer simulation of the formation of primordial stars that follows the relevant atomic and molecular processes in a primordial gas in an expanding universe. The results show that primeval density fluctuations left over from the Big Bang can drive the formation of a tiny protostar with a mass of just one percent that of the sun. The protostar is a seed for the subsequent formation of a massive primordial star.

  9. Bulk viscous cosmology in early Universe

    Indian Academy of Sciences (India)

    C P Singh

    2008-07-01

    The effect of bulk viscosity on the early evolution of Universe for a spatially homogeneous and isotropic Robertson-Walker model is considered. Einstein's field equations are solved by using `gamma-law' equation of state = ( - 1)ρ, where the adiabatic parameter gamma () depends on the scale factor of the model. The `gamma' function is defined in such a way that it describes a unified solution of early evolution of the Universe for inflationary and radiation-dominated phases. The fluid has only bulk viscous term and the coefficient of bulk viscosity is taken to be proportional to some power function of the energy density. The complete general solutions have been given through three cases. For flat space, power-law as well as exponential solutions are found. The problem of how the introduction of viscosity affects the appearance of singularity, is briefly discussed in particular solutions. The deceleration parameter has a freedom to vary with the scale factor of the model, which describes the accelerating expansion of the Universe.

  10. Thermodynamics in the Viscous Early Universe

    CERN Document Server

    Tawfik, A

    2010-01-01

    Assuming that the matter filling the background geometry in the Early Universe was a free gas and no phase transitions took place, we discuss the thermodynamics of this closed system using classical approaches. We found that essential cosmological quantities, such as the Hubble parameter $H$, the scaling factor $a$ and the curvature parameter $k$, can be derived from this simple model. The results are compatible with the Friedmann-Robertson-Walker model and Einstein field equations. Including finite bulk viscosity coefficient leads to important changes in the cosmological quantities. Accordingly, our picture about evolution of the Universe and its astrophysical consequences seems to be a subject of radical revision. We found that $k$ strongly depends on thermodynamics of the cosmic background matter. The time scale, at which negative curvature might take place, depends on the relation between the matter content and the total energy. Using quantum and statistical approaches, we introduced expressions for $H$ a...

  11. Exploring the Early Universe on Mobile Devices

    Science.gov (United States)

    Kocevski, Dale; McGrath, E. J.; CANDELS Collaboration

    2014-01-01

    The widespread adoption of smart phones and tablet computers has the potential to revolutionize the way in which educational material is shared with the general public. As part of the outreach effort for the CANDELS survey, we have developed a free interactive astronomy education application named Hubble Universe for iPad and iPhone devices. The application focuses on extragalactic science topics related to the CANDELS legacy survey, which is documenting galaxy evolution in the early universe. I will provide an overview of the application, which contains a wide range of interactive content, including 3D models of astrophysical phenomenon, informative diagrams and computer simulations. I will discuss how the application can be used to enhance classroom learning both by providing a database of interactive media and by encouraging students to explore astronomical topics away from traditional settings like the classroom or the desktop computer.

  12. Quantum coherent oscillations in the early universe

    CERN Document Server

    Pikovski, Igor

    2015-01-01

    Cosmic inflation is commonly assumed to be driven by quantum fields. Quantum mechanics predicts phenomena such as quantum fluctuations and tunneling of the field. Here we show an example of a quantum interference effect which goes beyond the semi-classical treatment and which may be of relevance in the early universe. We study the quantum coherent dynamics for a tilted, periodic potential, which results in genuine quantum oscillations of the inflaton field, analogous to Bloch oscillations in condensed matter and atomic systems. Our results show that quantum interference phenomena may be of relevance in cosmology.

  13. Turbulence and mixing in the early universe

    CERN Document Server

    Gibson, C H

    2001-01-01

    The role of turbulence and turbulent mixing in the formation and evolution of the early universe is examined. A new quantum-gravitational-dynamics model suggests that the mechanism of the hot big bang is functionally equivalent to the mechanism of turbulence, where an inertial-vortex force at Planck scales matches the Planck gravitational force and drives the formation of space-time-energy and the formation of more Planck particles, more spinning Planck-Kerr particles, and a big bang turbulence cascade to larger scales before cooling to the strong force freeze out temperature. Temperature fluctuations between the Planck temperature and strong force temperature are mixed by turbulence to give a Corrsin-Obukhov spectral form. Inflation fossilizes the turbulent temperature fluctuations by stretching them beyond the horizon scale of causal connection ct, where c is light speed and t is time. Fossil temperature turbulence fluctuations seed anisotropies in the nucleosynthesis of light elements, causing density fluc...

  14. Elementary particles in the early Universe

    CERN Document Server

    Gromov, Nikolai A

    2015-01-01

    The low energy limit of Electroweak Model is obtained from first principles of gauge theory. The very weak neutrino-matter interaction especially at low energies is explained by zero tending contraction parameter, which depend on the neutrino energy. The high-energy limit of Standard Model is generated by the contractions of gauge groups. Contraction parameters of gauge group $SU(2)$ of Electroweak Model and gauge group $SU(3)$ of Quantum Chromodynamics are taken identical and tending to zero when energy increase. At the infinite energy limit all particles lose masses, all quarks have only one color. Electroweak interactions become long-range and are mediated by the neutral currents. The limit model represents the development of Standard Model in the early Universe from the Big Bang up to the end of several milliseconds.

  15. Structure Formation in the Early Universe

    CERN Document Server

    Miedema, P G

    2016-01-01

    The evolution of the perturbations in the energy density and the particle number density in a flat Friedmann-Lemaitre-Robertson-Walker universe in the radiation-dominated era and in the epoch after decoupling of matter and radiation is studied. For large-scale perturbations the outcome is in accordance with treatments in the literature. For small-scale perturbations the differences are conspicuous. Firstly, in the radiation-dominated era small-scale perturbations grew proportional to the square root of time. Secondly, perturbations in the Cold Dark Matter particle number density were, due to gravitation, coupled to perturbations in the total energy density. This implies that structure formation has commenced successfully only after decoupling of matter and radiation. Finally, after decoupling density perturbations evolved diabatically, i.e., they exchanged heat with their environment. This heat exchange may have enhanced the growth rate of its mass sufficiently to explain structure formation in the early univ...

  16. Clustering Fossils from the Early Universe

    CERN Document Server

    Jeong, Donghui

    2012-01-01

    Many inflationary theories introduce new scalar, vector, or tensor degrees of freedom that may then affect the generation of primordial density perturbations. Here we show how to search a galaxy (or 21-cm) survey for the imprint of primordial scalar, vector, and tensor fields. These new fields induce local departures to an otherwise statistically isotropic two-point correlation function, or equivalently, nontrivial four-point correlation functions (or trispectra, in Fourier space), that can be decomposed into scalar, vector, and tensor components. We write down the optimal estimators for these various components and show how the sensitivity to these modes depends on the galaxy-survey parameters. New probes of parity-violating early-Universe physics are also presented.

  17. Nuclear matter in the early universe

    Energy Technology Data Exchange (ETDEWEB)

    Barros, Celso de Camargo, E-mail: barros.celso@ufsc.br [Depto de Física - CFM - Universidade Federal de Santa Catarina - Florianópolis - SC - CP. 476 - CEP 88.040 - 900 - Brazil (Brazil); Cunha, Ivan Eugênio da, E-mail: lordlihige@hotmail.com [Centro Brasileiro de Pesquisas Físicas - CBPF - Rio de Janeiro (Brazil)

    2015-12-17

    Recently, extreme conditions have been obtained in ultra-relativistic heavy ion collisions at RHIC and at the Large Hadron collider. It is believed that these conditions are similar to the ones of the early Universe, in the time between 10{sup −6}s and 1s, approximately. In this work, the hadrons produced in this range of time will be studied, considering some aspects of the systems produced in the heavy-ion collisions. We will study a phase posterior to the phase transition (in fact it is believed to be a crossover) from the quark-gluon plasma, that is the hadronic phase of the Universe. We will show the model proposed in [1], considering the hadronic matter described by a relativistic model (similar to the Walecka model), considering particles described by quantum equations in a curved spacetime. This curvature is due to the mass and to the strong interactions that appears in the energy-momentum tensor. The set of the equations is proposed in the Robertson-Walker metric, and some approximate solutions are obtained.

  18. Compton Composites Late in the Early Universe

    Directory of Open Access Journals (Sweden)

    Frederick Mayer

    2014-07-01

    Full Text Available Beginning roughly two hundred years after the big-bang, a tresino phase transition generated Compton-scale composite particles and converted most of the ordinary plasma baryons into new forms of dark matter. Our model consists of ordinary electrons and protons that have been bound into mostly undetectable forms. This picture provides an explanation of the composition and history of ordinary to dark matter conversion starting with, and maintaining, a critical density Universe. The tresino phase transition started the conversion of ordinary matter plasma into tresino-proton pairs prior to the the recombination era. We derive the appropriate Saha–Boltzmann equilibrium to determine the plasma composition throughout the phase transition and later. The baryon population is shown to be quickly modified from ordinary matter plasma prior to the transition to a small amount of ordinary matter and a much larger amount of dark matter after the transition. We describe the tresino phase transition and the origin, quantity and evolution of the dark matter as it takes place from late in the early Universe until the present.

  19. Stochastic evolution of cosmological parameters in the early universe

    Indian Academy of Sciences (India)

    C Sivakumar; Moncy V John; K Babu Joseph

    2001-04-01

    We develop a stochastic formulation of cosmology in the early universe, after considering the scatter in the redshift-apparent magnitude diagram in the early epochs as an observational evidence for the non-deterministic evolution of early universe. We consider the stochastic evolution of density parameter in the early universe after the inflationary phase qualitatively, under the assumption of fluctuating factor in the equation of state, in the Fokker–Planck formalism. Since the scale factor for the universe depends on the energy density, from the coupled Friedmann equations we calculated the two variable probability distribution function assuming a flat space geometry

  20. Early universe thermostatistics in curved momentum spaces

    CERN Document Server

    Gorji, M A; Nozari, K; Vakili, B

    2016-01-01

    The theories known as doubly special relativity are introduced in order to take into account an observer-independent length scale and the speed of light in the framework of special relativity. These theories can be generally formulated on the de Sitter and also recently proposed anti-de Sitter momentum spaces. In the context of these theories, we study the statistical mechanics and to do this, we consider the natural measure on the corresponding extended phase space. The invariant measure on the space of distinct microstates is obtained by restriction of the natural measure of the extended phase space to the physical phase space through the disintegration theorem. Having the invariant measure, one can study the statistical mechanics in arbitrary ensemble for any doubly special relativity theory. We use the constructed setup to study the statistical properties of four doubly special relativity models. Applying the results to the case of early universe thermodynamics, we show that one of these models that is de...

  1. Bondi accretion in the early universe

    CERN Document Server

    Ricotti, Massimo

    2007-01-01

    This paper presents a study of quasi-steady spherical accretion in the early Universe, before the formation of the first stars and galaxies. The main motivation is to derive the basic formulas that will be used in a companion paper to calculate the accretion luminosity of primordial black holes and their effect on the cosmic ionization history. The following cosmological effects are investigated: the coupling of the gas to the CMB photon fluid (i.e., Compton drag), Hubble expansion, and the growth of the dark matter halo seeded by the gravitational potential of the central point mass. The gas equations of motion are solved assuming either a polytropic or an isothermal equation of state. We consider the cases in which the accreting object is a point mass or a spherical dark matter halo with power-law density profile, as predicted by the theory of "secondary infall''. Analytical solutions for the sonic radius and fitting formulas for the accretion rate are provided. Different accretion regimes exist depending o...

  2. Connecting QGP-Heavy Ion Physics to the Early Universe

    CERN Document Server

    Rafelski, Johann

    2013-01-01

    We discuss properties and evolution of quark-gluon plasma in the early Universe and compare to laboratory heavy ion experiments. We describe how matter and antimatter emerged from a primordial soup of quarks and gluons. We focus our discussion on similarities and differences between the early Universe and the laboratory experiments.

  3. Connecting QGP-Heavy Ion Physics to the Early Universe

    Science.gov (United States)

    Rafelski, Johann

    2013-10-01

    We discuss properties and evolution of quark-gluon plasma in the early Universe and compare to laboratory heavy ion experiments. We describe how matter and antimatter emerged from a primordial soup of quarks and gluons. We focus our discussion on similarities and differences between the early Universe and the laboratory experiments.

  4. Connecting QGP-Heavy Ion Physics to the Early Universe

    Energy Technology Data Exchange (ETDEWEB)

    Rafelski, Johann

    2013-10-15

    We discuss properties and evolution of quark-gluon plasma in the early Universe and compare to laboratory heavy ion experiments. We describe how matter and antimatter emerged from a primordial soup of quarks and gluons. We focus our discussion on similarities and differences between the early Universe and the laboratory experiments.

  5. Cosmic Radiation Fields: Sources in the early Universe

    Science.gov (United States)

    Raue, Martin; Kneiske, Tanja; Horns, Dieter; Elsaesser, Dominik; Hauschildt, Peter

    The workshop "Cosmic Radiation Fields - Sources in the Early Universe" (CRF 2010) focuses on the connection between the extragalactic infrared background and sources in the early universe, in particular stars powered by dark matter burning (Dark Stars; DS). The workshop covers the following topics: the cosmic infrared background, formation of early stars, dark stars, effect of dark matter in the early universe, dark matter halos, primordial star formation rate, and reionization. Further information can be found on the conference webpage: http://www.desy.de/crf2010/. Organizing committee: Tanja Kneiske, Martin Raue, Dominik Elsaesser, Alexander Gewering-Peine, Peter Hausschildt, Dieter Horns, and Andreas Maurer.

  6. The emergence and early evolution of biological carbon-fixation.

    Directory of Open Access Journals (Sweden)

    Rogier Braakman

    Full Text Available The fixation of CO₂ into living matter sustains all life on Earth, and embeds the biosphere within geochemistry. The six known chemical pathways used by extant organisms for this function are recognized to have overlaps, but their evolution is incompletely understood. Here we reconstruct the complete early evolutionary history of biological carbon-fixation, relating all modern pathways to a single ancestral form. We find that innovations in carbon-fixation were the foundation for most major early divergences in the tree of life. These findings are based on a novel method that fully integrates metabolic and phylogenetic constraints. Comparing gene-profiles across the metabolic cores of deep-branching organisms and requiring that they are capable of synthesizing all their biomass components leads to the surprising conclusion that the most common form for deep-branching autotrophic carbon-fixation combines two disconnected sub-networks, each supplying carbon to distinct biomass components. One of these is a linear folate-based pathway of CO₂ reduction previously only recognized as a fixation route in the complete Wood-Ljungdahl pathway, but which more generally may exclude the final step of synthesizing acetyl-CoA. Using metabolic constraints we then reconstruct a "phylometabolic" tree with a high degree of parsimony that traces the evolution of complete carbon-fixation pathways, and has a clear structure down to the root. This tree requires few instances of lateral gene transfer or convergence, and instead suggests a simple evolutionary dynamic in which all divergences have primary environmental causes. Energy optimization and oxygen toxicity are the two strongest forces of selection. The root of this tree combines the reductive citric acid cycle and the Wood-Ljungdahl pathway into a single connected network. This linked network lacks the selective optimization of modern fixation pathways but its redundancy leads to a more robust topology

  7. Carbon cycle and climate commitments from early human interference

    Science.gov (United States)

    Zickfeld, K.; Solomon, S.

    2015-12-01

    According to the early anthropogenic hypothesis proposed by Ruddiman (2003), human influence on Earth's climate began several thousand years before the beginning of the industrial era. Agriculture and deforestation starting around 8000 years before present (BP) and slowly increasing over the Holocene, would have led to an increase in atmospheric methane (CH4) and carbon dioxide (CO2) concentration, preventing a natural cooling of Earth's climate. Here, the emphasis is not on testing Ruddiman's hypothesis, but rather on exploring the carbon cycle and climate commitment from potential early CH4 and CO2 emissions. In contrast to modern greenhouse gas emissions, early emissions occurred over millennia, allowing the climate system to come to near-equilibrium with the applied forcing. We perform two transient Holocene simulations with an Earth system model of intermediate complexity - the University of Victoria Earth System Climate Model (UVic ESCM). The first simulation is a standard transient Holocene simulation, forced with reconstructed changes in CO2 and CH4 concentrations and orbital and volcanic forcing. The second simulation is forced with CO2 and CH4 concentrations corrected for the net anthropogenic contribution postulated by Ruddiman (2007), with other forcings evolving as in the standard simulation. The difference in diagnosed emissions between the two simulations allows us to determine the anthropogenic emissions. After year 1850, anthropogenic CO2 and CH4 emissions are set to zero and the simulations continued for several hundred years. In this paper, we analyze the carbon cycle and climate response to the applied forcings, and quantify the resulting (post 1850) commitment from early anthropogenic interference.

  8. Quantum aspects of early universe thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Drewes, Marco

    2010-03-15

    Various features of the observable universe can be understood as the result of nonequilibrium processes during the early stages of its history, when it was filled with a hot primordial plasma. In many cases, including cosmological freezeout processes, only a few degrees of freedom were out of equilibrium and the background plasma can be viewed as a large heat bath to which these couple. We study scalar and fermionic quantum fields out of thermal equilibrium that are weakly coupled to a large thermal bath with the goal to formulate a full quantum mechanical description of such processes. The bath composition need not be specified. Our analysis is based on Kadanoff-Baym equations, which are the exact equations of motion for the correlation functions in a nonequilibrium quantum system. We solve the equations of motion for the most general Gaussian initial density matrix, without a specific ansatz or a-priori parameterisation and for arbitrarily large deviations from equilibrium. The solutions depend on integral kernels that contain memory effects. These can in good approximation be solved analytically when the field excitations have a small decay width. The full solutions are compared to results obtained by other methods. We prove that the description in terms of a stochastic Langevin equation is equivalent to the Kadanoff-Baym equations. We show the emergence of standard Boltzmann equations as a limit of the Kadanoff-Baym equations in a dilute gas when coherences play no role and discuss quantum Boltzmann equations as an intermediate step. We analyse the properties of the solutions in terms of the equation of state and investigate the validity and implications of quasiparticle approximations. We find that the equation of state can deviate significantly from that of a gas of quasiparticles even if the resonances in the plasma show quasiparticle behaviour in decays and scatterings. A detailed discussion is devoted to the influence of modified dispersion relations and

  9. Fundamental Field Theory in Ten Dimensions and The Early Universe

    CERN Document Server

    Patwardhan, A

    2006-01-01

    A unified field theory in ten dimensions, of all interactions, can describe high energy processes occuring in the early universe. In such a theory transitions that give properties of the universe can occur due to the presence of algebraic and geometric structures. A correspondence between theory and observations of the universe is made, to obtain a new interpretation and properties. This paper consists of a field theory and cosmological model of dark and normal energy and matter, cosmological constant, acceleration and inflation in the early universe.

  10. Quark-Gluon Plasma: from accelerator experiments to early Universe

    CERN Document Server

    Rosnet, P

    2015-01-01

    In the Big Bang scenario, the early Universe is characterized by the {\\it particle era}, i.e. a Universe made of particles. This period connects both scales of fundamental physics: infinitesimally small and infinitely large. So, particle physics and in particular experimental programs at accelerators can bring valuable inputs for the understanding of the early Universe and its evolution. These proceedings discuss the impact of the Quantum ChromoDynamics phase transition experienced by the {\\it particle era} in the expanding Universe, which is connected to the study of the Quark-Gluon Plasma produced in heavy-ion physics experiments.

  11. Sterile neutrinos in the early universe

    NARCIS (Netherlands)

    Ivashko, Artem

    2015-01-01

    Although the Standard Model of elementary particles successfully describes the Universe up to the smallest known scales, we know that there exists a number of observational phenomena, which do not find explanation in the framework of this theory. Among these problems are Neutrino Oscillations, Dark

  12. Sterile neutrinos in the early universe

    NARCIS (Netherlands)

    Ivashko, Artem

    2015-01-01

    Although the Standard Model of elementary particles successfully describes the Universe up to the smallest known scales, we know that there exists a number of observational phenomena, which do not find explanation in the framework of this theory. Among these problems are Neutrino Oscillations, Dark

  13. Assessing Carbon Dioxide Emissions from Energy Use at a University

    Science.gov (United States)

    Riddell, William; Bhatia, Krishan Kumar; Parisi, Matthew; Foote, Jessica; Imperatore, John, III

    2009-01-01

    Purpose: The purpose of this paper is to assess the carbon dioxide emissions associated with electric, HVAC, and hot water use from a US university. Design/methodology/approach: First, the total on-campus electrical, natural gas and oil consumption for an entire year was assessed. For each category of energy use, the carbon associated with…

  14. Assessing Carbon Dioxide Emissions from Energy Use at a University

    Science.gov (United States)

    Riddell, William; Bhatia, Krishan Kumar; Parisi, Matthew; Foote, Jessica; Imperatore, John, III

    2009-01-01

    Purpose: The purpose of this paper is to assess the carbon dioxide emissions associated with electric, HVAC, and hot water use from a US university. Design/methodology/approach: First, the total on-campus electrical, natural gas and oil consumption for an entire year was assessed. For each category of energy use, the carbon associated with…

  15. Scale Factor in Very Early Universe with the Extra Dimensions

    CERN Document Server

    Mohsenzadeh, M

    2010-01-01

    The main goal of this paper is presentation an expanding scenario of 5-dimensional space-time in the very early universe. We introduce the 5-dimensional generalized FRW metric and obtain the evolution of the bulk scale factor with space-like and time-like extra dimensions. It is shown that, additional space-like dimensions can produce an exponentially expansion for the bulk scale factor under repulsive strong gravitational force in the empty very early universe with the extra dimension.

  16. Peeking into galaxies in early days of the Universe

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ An international consortium of astronomers, in Acluding a CAS astrophysicist, has revealed how galaxies looked like in early days of the Universe. They discovered that massive galaxies already existed when the Universe is one fifth of its current age, posing challenges to the widely accepted hierarchical model of galaxy formation.

  17. Origin of masses in the Early Universe

    CERN Document Server

    Pervushin, Victor N; Cherny, Alexander Yu; Shilin, Vadim I; Nazmitdinov, Rashid G; Pavlov, Alexander E; Pichugin, Konstantin N; Zakharov, Alexander F

    2015-01-01

    New model is suggested, where the Casimir mechanism is the source of masses and conformal symmetry breaking at the Planck epoch in the beginning of the Universe. The mechanism is the Casimir energy and associated condensate, which are resulted from the vacuum postulate and normal ordering of the conformal invariant Hamiltonian with respect to the quantum elementary field operators. It is shown that the Casimir top-quark condensate specifies the value of the Higgs particle mass without involving the Higgs tachyon mass, which is put equal to zero. The Casimir mechanism yields another value of the coupling constant for the self-interaction of scalar field than the standard model does.

  18. Numerical relativity and the early Universe

    Directory of Open Access Journals (Sweden)

    Mironov Sergey

    2016-01-01

    Full Text Available We consider numerical simulations in general relativity in ADM formalism with cosmological ansatz for the metric. This ansatz is convenient for investigations of the Universe creation in laboratory with Galileons. Here we consider toy model for the software: spherically symmetric scalar field minimally coupled to the gravity with asymmetric double well potential. We studied the dependence of radius of critical bubble on the parameters of the theory. It demonstrates the wide applicability of thin-wall approximation. We did not find any kind of stable bubble solution.

  19. Supermassive Black Holes in the Early Universe

    CERN Document Server

    Melia, Fulvio

    2015-01-01

    The recent discovery of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.3 has exacerbated the time compression problem implied by the appearance of supermassive black holes only ~900 Myr after the big bang, and only ~500 Myr beyond the formation of Pop II and III stars. Aside from heralding the onset of cosmic reionization, these first and second generation stars could have reasonably produced the ~5-20 solar-mass seeds that eventually grew into z~6-7 quasars. But this process would have taken ~900 Myr, a timeline that appears to be at odds with the predictions of LCDM without an anomalously high accretion rate, or some exotic creation of ~10^5 solar-mass seeds. There is no evidence of either of these happening in the local universe. In this paper, we show that a much simpler, more elegant solution to the supermassive black hole anomaly is instead to view this process using the age-redshift relation predicted by the R_h=ct Universe, an FRW cosmology with zero active mass. In this context, cosm...

  20. Using Supercomputers to Probe the Early Universe

    Energy Technology Data Exchange (ETDEWEB)

    Giorgi, Elena Edi [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-17

    For decades physicists have been trying to decipher the first moments after the Big Bang. Using very large telescopes, for example, scientists scan the skies and look at how fast galaxies move. Satellites study the relic radiation left from the Big Bang, called the cosmic microwave background radiation. And finally, particle colliders, like the Large Hadron Collider at CERN, allow researchers to smash protons together and analyze the debris left behind by such collisions. Physicists at Los Alamos National Laboratory, however, are taking a different approach: they are using computers. In collaboration with colleagues at University of California San Diego, the Los Alamos researchers developed a computer code, called BURST, that can simulate conditions during the first few minutes of cosmological evolution.

  1. Mixing Metals in the Early Universe

    CERN Document Server

    Ferrara, A; Shchekinov, Yu A; Ferrara, Andrea; Pettini, Max; Shchekinov, Yuri

    2000-01-01

    We investigate the evolution of the metallicity of the intergalactic medium (IGM) with particular emphasis on its spatial distribution. We propose that metal enrichment occurs as a two step process. First, supernova (SN) explosions eject metals into relatively small regions confined to the surroundings of star-forming galaxies. From a comprehensive treatment of blowout we show that SNae by themselves fail by more than one order of magnitude to distribute the products of stellar nucleosynthesis over volumes large enough to pollute the whole IGM to the metallicity levels observed. Thus, a additional (but as yet unknown) physical mechanism must be invoked to mix the metals on scales comparable to the mean distance between the galaxies which are most efficient pollutants. From this simple hypothesis we derive a number of testable predictions for the evolution of the IGM metallicity. Specifically, we find that: (i) the fraction of metals ejected over the star formation history of the universe is about 50% at z=0; ...

  2. Early Predictors of First-Year Academic Success at University: Pre-University Effort, Pre-University Self-Efficacy, and Pre-University Reasons for Attending University

    Science.gov (United States)

    van Herpen, Sanne G. A.; Meeuwisse, Marieke; Hofman, W. H. Adriaan; Severiens, Sabine E.; Arends, Lidia R.

    2017-01-01

    Given the large number of dropouts in the 1st year at university, it is important to identify early predictors of 1st-year academic success. The present study (n = 453 first-year students) contributes to literature on the transition from secondary to higher education by investigating how the non-cognitive factors "pre-university" effort…

  3. Black holes in the early Universe.

    Science.gov (United States)

    Volonteri, Marta; Bellovary, Jillian

    2012-12-01

    The existence of massive black holes (MBHs) was postulated in the 1960s, when the first quasars were discovered. In the late 1990s their reality was proven beyond doubt in the Milky way and a handful nearby galaxies. Since then, enormous theoretical and observational efforts have been made to understand the astrophysics of MBHs. We have discovered that some of the most massive black holes known, weighing billions of solar masses, powered luminous quasars within the first billion years of the Universe. The first MBHs must therefore have formed around the time the first stars and galaxies formed. Dynamical evidence also indicates that black holes with masses of millions to billions of solar masses ordinarily dwell in the centers of today's galaxies. MBHs populate galaxy centers today, and shone as quasars in the past; the quiescent black holes that we detect now in nearby bulges are the dormant remnants of this fiery past. In this review we report on basic, but critical, questions regarding the cosmological significance of MBHs. What physical mechanisms led to the formation of the first MBHs? How massive were the initial MBH seeds? When and where did they form? How is the growth of black holes linked to that of their host galaxy? The answers to most of these questions are works in progress, in the spirit of these reports on progress in physics.

  4. Black hole formation in the early universe

    CERN Document Server

    Latif, M A; Schmidt, W; Niemeyer, J

    2013-01-01

    Supermassive black holes with up to a $\\rm 10^{9}~M_{\\odot}$ dwell in the centers of present-day galaxies, and their presence has been confirmed at z $\\geq$ 6. Their formation at such early epochs is still an enigma. Different pathways have been suggested to assemble supermassive black holes in the first billion years after the Big Bang. Direct collapse has emerged as a highly plausible scenario to form black holes as it provides seed masses of $\\rm 10^{5}-10^{6}~M_{\\odot}$. Gravitational collapse in atomic cooling haloes with virial temperatures T$_{vir} \\geq 10^{4}$~K may lead to the formation of massive seed black holes in the presence of an intense background UV flux. Turbulence plays a central role in regulating accretion and transporting angular momentum. We present here the highest resolution cosmological large-eddy simulations to date which track the evolution of high-density regions on scales of $0.25$~AU beyond the formation of the first peak, and study the impact of subgrid-scale turbulence. The pe...

  5. Universal Features of Quantized Thermal Conductance of Carbon Nanotubes

    OpenAIRE

    Yamamoto, Takahiro; Watanabe, Satoshi; Watanabe, Kazuyuki

    2003-01-01

    The universal features of quantized thermal conductance of carbon nanotubes (CNTs) are revealed through theoretical analysis based on the Landauer theory of heat transport. The phonon-derived thermal conductance of semiconducting CNTs exhibits a universal quantization in the low temperature limit, independent of the radius or atomic geometry. The temperature dependence follows a single curve given in terms of temperature scaled by the phonon energy gap. The thermal conductance of metallic CNT...

  6. Fate of Yang-Mills black hole in early Universe

    Energy Technology Data Exchange (ETDEWEB)

    Nakonieczny, Lukasz; Rogatko, Marek [Institute of Physics Maria Curie-Sklodowska University 20-031 Lublin, pl. Marii Curie-Sklodowskiej 1 (Poland)

    2013-02-21

    According to the Big Bang Theory as we go back in time the Universe becomes progressively hotter and denser. This leads us to believe that the early Universe was filled with hot plasma of elementary particles. Among many questions concerning this phase of history of the Universe there are questions of existence and fate of magnetic monopoles and primordial black holes. Static solution of Einstein-Yang-Mills system may be used as a toy model for such a black hole. Using methods of field theory we will show that its existence and regularity depend crucially on the presence of fermions around it.

  7. Early Tracking or Finally Leaving? Determinants of Early Study Success in First-Year University Students

    Science.gov (United States)

    Brouwer, Jasperina; Jansen, Ellen; Hofman, Adriaan; Flache, Andreas

    2016-01-01

    Two theoretical approaches underlie this investigation of the determinants of early study success among first-year university students. Specifically, to extend Walberg's educational productivity model, this study draws on the expectancy-value theory of achievement motivation in a contemporary university context. The survey data came from 407…

  8. The Union University "Early Bird" Internship Program in Teacher Education.

    Science.gov (United States)

    Union Univ., Jackson, TN.

    The Early Bird Internship Program in Teacher Education at Union University was developed to give the sophomore student a general field orientation to the whole school program prior to the senior student teaching program. In partial fulfillment of the requirements for a beginning course for all prospective teachers taken near the end of the…

  9. Gravitino Condensates in the Early Universe and Inflation

    CERN Document Server

    Mavromatos, Nick E

    2015-01-01

    We review work on the formation of gravitino condensates via the super-Higgs effect in the early Universe. This is a scenario for both inflating the early universe and breaking local supersymmetry (supergravity), entirely independent of any coupling to external matter. The goldstino mode associated with the breaking of (global) supersymmetry is "eaten" by the gravitino field, which becomes massive (via its own vacuum condensation) and breaks the local supersymmetry (supergravity) dynamically. The most natural association of gravitino condensates with inflation proceeds in an indirect way, via a Starobinsky-inflation-type phase. The higher-order curvature corrections of the (quantum) effective action of gravitino condensates induced by integrating out massive gravitino degrees of freedom in a curved space-time background, in the broken-supergravity phase, are responsible for inducing a scalar mode which inflates the Universe. The scenario is in agreement with Planck data phenomenology in a natural and phenomen...

  10. Emergent Consciousness From the Early Universe to Our Mind

    CERN Document Server

    Zizzi, P A

    2000-01-01

    In a previous paper (gr-qc/9907063) we described the early inflationary universe in terms of quantum information. In this paper, we analize those results in more detail, and we stress the fact that, during inflation, the universe can be described as a superposed state of quantum registers. The self-reduction of the superposed quantum state is consistent with the Penrose's Objective Reduction (OR) model. The quantum gravity threshold is reached at the end of inflation, and corresponds to a superposed state of 10^9 quantum registers. This is also the number of superposed tubulins-qubits in our brain, which undergo the Penrose-Hameroff's Orchestrated Objective Reduction, (Orch OR), leading to a conscious event. Then, an analogy naturally arises between the very early quantum computing universe,and our mind.

  11. CMB spectral distortions and energy release in the early universe

    Science.gov (United States)

    Tashiro, Hiroyuki

    2014-06-01

    Measuring the spectral deviation of the cosmic microwave background (CMB) from the blackbody spectrum has become a focus of attention as a probe of the thermal history of the Universe. It has been more than 20 years since COBE/FIRAS's measurement, which showed excellent agreement between the CMB spectrum and a perfect blackbody spectrum. Significant developments in the technology since then have allowed us to improve the sensitivity of the absolute spectrum measurement by a factor of {˜ }10^4. Therefore, the physics related to the generation of CMB spectral distortions should now be investigated in greater detail. To probe the physics in the early universe and to open an observational window for new physics, various energy release mechanisms both in and beyond standard cosmology need to be studied. In this paper, we provide a review of the physics of CMB distortions and the energy release that creates CMB distortions in the early universe.

  12. Horava-Lifshitz early universe phase transition beyond detailed balance

    Energy Technology Data Exchange (ETDEWEB)

    Kheyri, F.; Khodadi, M.; Sepangi, H.R. [Shahid Beheshti University, Department of Physics, Tehran (Iran, Islamic Republic of)

    2013-01-15

    The early universe is believed to have undergone a QCD phase transition to hadrons at about 10 {mu}s after the big bang. We study such a transition in the context of the non-detailed balance Horava-Lifshitz theory by investigating the effects of the dynamical coupling constant {lambda} in a flat universe. The evolution of the relevant physical quantities, namely the energy density {rho}, temperature T, scale factor a and the Hubble parameter H is investigated before, during and after the phase transition, assumed to be of first order. Also, in view of the recent lattice QCD simulations data, we study a cross-over phase transition of the early universe whose results are based on two different sets of lattice data. (orig.)

  13. The Early Universe: Searching for Evidence of Cosmic Inflation

    Science.gov (United States)

    Chuss, David T.

    2012-01-01

    In the past two decades, our understanding of the evolution and fate of the universe has increased dramatically. This "Age of Precision Cosmology" has been ushered in by measurements that have both elucidated the details of the Big Bang cosmology and set the direction for future lines of inquiry. Our universe appears to consist of 5% baryonic matter; 23% of the universe's energy content is dark matter which is responsible for the observed structure in the universe; and 72% of the energy density is so-called "dark energy" that is currently accelerating the expansion of the universe. In addition, our universe has been measured to be geometrically flat to 1 %. These observations and related details of the Big Bang paradigm have hinted that the universe underwent an epoch of accelerated expansion known as "inflation" early in its history. In this talk, I will review the highlights of modern cosmology, focusing on the contributions made by measurements of the cosmic microwave background, the faint afterglow of the Big Bang. I will also describe new instruments designed to measure the polarization of the cosmic microwave background in order to search for evidence of cosmic inflation.

  14. Hypermagnetic helicity evolution in early universe: leptogenesis and hypermagnetic diffusion

    OpenAIRE

    Semikoz, V. B.; Smirnov, A.Yu.(Max-Planck-Institute for Nuclear Physics, Saupfercheckweg 1, D-69117, Heidelberg, Germany); Sokoloff, D. D.

    2013-01-01

    We study hypermagnetic helicity and lepton asymmetry evolution in plasma of the early Universe before the electroweak phase transition (EWPT) accounting for chirality flip processes via inverse Higgs decays and sphaleron transitions which violate the left lepton number and wash out the baryon asymmetry of the Universe (BAU). In the scenario where the right electron asymmetry supports the BAU alone through the conservation law $B/3 - L_{eR}=const$ at temperatures $T>T_{RL}\\simeq 10 TeV$ the fo...

  15. Carbon Nanotube Film-Based Speaker Developed in Tsinghua University

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ A research group from Tsinghua University led by Prof.Fan Shoushan,Member of the Chinese Academy of Sciences,and Jiang Kaili,associate professor of Physics,found that carbon nanotube thin film could act as a speaker once fed by audio frequency electric currents.These carbon nanotube loudspeakers are only tens of a nanometer thick,transparent,flexible and stretchable,which can be further tailored into any shape and size.These results have been published in the journal Nano Letter.

  16. Discovery of a Perseus-like cloud in the early Universe. H I-to-H2 transition, carbon monoxide and small dust grains at zabs≈ 2.53 towards the quasar J0000+0048

    Science.gov (United States)

    Noterdaeme, P.; Krogager, J.-K.; Balashev, S.; Ge, J.; Gupta, N.; Krühler, T.; Ledoux, C.; Murphy, M. T.; Pâris, I.; Petitjean, P.; Rahmani, H.; Srianand, R.; Ubachs, W.

    2017-01-01

    We present the discovery of a molecular cloud at zabs ≈ 2.5255 along the line of sight to the quasar SDSS J 000015.17+004833.3. We use a high-resolution spectrum obtained with the Ultraviolet and Visual Echelle Spectrograph together with a deep multi-wavelength medium-resolution spectrum obtained with X-shooter (both on the Very Large Telescope) to perform a detailed analysis of the absorption lines from ionic, neutral atomic and molecular species in different excitation levels, as well as the broad-band dust extinction. We find that the absorber classifies as a Damped Lyman-α system (DLA) with log N(H i) (cm-2) = 20.8 ± 0.1. The DLA has super-solar metallicity (Z 2.5 Z⊙, albeit to within a factor of two to three) with a depletion pattern typical of cold gas and an overall molecular fraction f = 2N(H2)/(2N(H2) + N(H i)) 50%. This is the highest f-value observed to date in a high-z intervening system. Most of the molecular hydrogen arises from a clearly identified narrow (b 0.7km s-1), cold component in which carbon monoxide molecules are also found, with log N(CO)≈ 15. With the help of the spectral synthesis code Cloudy, we study the chemical and physical conditions in the cold gas. We find that the line of sight probes the gas deep after the H i-to-H2 transition in a 4-5 pc-size cloud with volumic density nH 80 cm-3 and temperature of only 50 K. Our model suggests that the presence of small dust grains (down to about 0.001 μm) and high cosmic ray ionisation rate (ζH a few times 10-15 s-1) are needed to explain the observed atomic and molecular abundances. The presence of small grains is also in agreement with the observed steep extinction curve that also features a 2175 Å bump. Interestingly, the chemical and physical properties of this cloud are very similar to what is seen in diffuse molecular regions of the nearby Perseus complex, despite the former being observed when the Universe was only 2.5 Gyr old. The high excitation temperature of CO

  17. Dissipative Processes in the Early Universe: Bulk Viscosity

    CERN Document Server

    Tawfik, A; Mansour, H; Wahba, M

    2009-01-01

    In this talk, we discuss one of the dissipative processes which likely take place in the Early Universe. We assume that the matter filling the isotropic and homogeneous background is to be described by a relativistic viscous fluid characterized by an ultra-relativistic equation of state and finite bulk viscosity deduced from recent lattice QCD calculations and heavy-ion collisions experiments. We concentrate our treatment to bulk viscosity as one of the essential dissipative processes in the rapidly expanding Early Universe and deduce the dependence of the scale factor and Hubble parameter on the comoving time $t$. We find that both scale factor and Hubble parameter are finite at $t=0$, revering to absence of singularity. We also find that their evolution apparently differs from the one resulting in when assuming that the background matter is an ideal and non-viscous fluid.

  18. Unavoidable strong magnetic fields in the early Universe

    CERN Document Server

    Wagstaff, Jacques M; Schleicher, Dominik; Sigl, Guenter

    2013-01-01

    In this letter we show that the Universe is already strongly magnetised at very early epochs during cosmic evolution. Our calculations are based on the efficient amplification of weak magnetic seed fields, which are unavoidably present in the early Universe, by the turbulent small-scale dynamo (SSD). We identify at least one epoch during the radiation dominated regime where all the necessities for the SSD to work are fulfilled. Hence, at scales of $l_c\\sim0.3$ pc, the comoving field strength due to this mechanism will be $B_0\\sim0.35\\varepsilon^{1/2}$ nG at the present time, where $\\varepsilon$ is the saturation efficiency.

  19. The Transient High Energy Sky and Early Universe Surveyor

    Science.gov (United States)

    O'Brien, P. T.

    2016-04-01

    The Transient High Energy Sky and Early Universe Surveyor is a mission which will be proposed for the ESA M5 call. THESEUS will address multiple components in the Early Universe ESA Cosmic Vision theme:4.1 Early Universe,4.2 The Universe taking shape, and4.3 The evolving violent Universe.THESEUS aims at vastly increasing the discovery space of the high energy transient phenomena over the entire cosmic history. This is achieved via a unique payload providing an unprecedented combination of: (i) wide and deep sky monitoring in a broad energy band(0.3 keV-20 MeV; (ii) focusing capabilities in the soft X-ray band granting large grasp and high angular resolution; and (iii) on board near-IR capabilities for immediate transient identification and first redshift estimate.The THESEUS payload consists of: (i) the Soft X--ray Imager (SXI), a set of Lobster Eye (0.3--6 keV) telescopes with CCD detectors covering a total FOV of 1 sr; (ii) the X--Gamma-rays spectrometer (XGS), a non-imaging spectrometer (XGS) based on SDD+CsI, covering the same FOV than the Lobster telescope extending the THESEUS energy band up to 20 MeV; and (iii) a 70cm class InfraRed Telescope (IRT) observing up to 2 microns with imaging and moderate spectral capabilities.The main scientific goals of THESEUS are to:(a) Explore the Early Universe (cosmic dawn and reionization era) by unveiling the Gamma--Ray Burst (GRBs) population in the first billion years}, determining when did the first stars form, and investigating the re-ionization epoch, the interstellar medium (ISM) and the intergalactic medium (IGM) at high redshifts.(b) Perform an unprecedented deep survey of the soft X-ray transient Universe in order to fill the present gap in the discovery space of new classes of transient; provide a fundamental step forward in the comprehension of the physics of various classes of Galactic and extra--Galactic transients, and provide real time trigger and accurate locations of transients for follow-up with next

  20. A Physical – Geometrical Model of an Early Universe

    Directory of Open Access Journals (Sweden)

    Corneliu BERBENTE

    2014-12-01

    Full Text Available A physical-geometrical model for a possible early universe is proposed. One considers an initial singularity containing the energy of the whole universe. The singularity expands as a spherical wave at the speed of light generating space and time. The relations of the special theory of relativity, quantum mechanics and gas kinetics are considered applicable. A structuring of the primary wave is adopted on reasons of geometrical simplicity as well as on satisfying the conservation laws. The evolution is able to lead to particles very close to neutrons as mass and radius. The actually admitted values for the radius and mass of the universe as well as the temperature of the ground radiation (3-5 K can be obtained by using the proposed model.

  1. Feedback in low-mass galaxies in the early Universe.

    Science.gov (United States)

    Erb, Dawn K

    2015-07-09

    The formation, evolution and death of massive stars release large quantities of energy and momentum into the gas surrounding the sites of star formation. This process, generically termed 'feedback', inhibits further star formation either by removing gas from the galaxy, or by heating it to temperatures that are too high to form new stars. Observations reveal feedback in the form of galactic-scale outflows of gas in galaxies with high rates of star formation, especially in the early Universe. Feedback in faint, low-mass galaxies probably facilitated the escape of ionizing radiation from galaxies when the Universe was about 500 million years old, so that the hydrogen between galaxies changed from neutral to ionized-the last major phase transition in the Universe.

  2. Numerical Relativity as a Tool for Studying the Early Universe

    Directory of Open Access Journals (Sweden)

    David Garrison

    2014-01-01

    Full Text Available Numerical simulations are becoming a more effective tool for conducting detailed investigations into the evolution of our universe. In this paper, we show how the framework of numerical relativity can be used for studying cosmological models. The author is working to develop a large-scale simulation of the dynamical processes in the early universe. These take into account interactions of dark matter, scalar perturbations, gravitational waves, magnetic fields, and turbulent plasma. The code described in this report is a GRMHD code based on the Cactus framework and is structured to utilize one of several different differencing methods chosen at run-time. It is being developed and tested on the University of Houston’s Maxwell cluster.

  3. Do we have a theory of early universe cosmology?

    Science.gov (United States)

    Brandenberger, Robert

    2014-05-01

    The inflationary scenario has become the paradigm of early universe cosmology, and - in conjunction with ideas from superstring theory-has led to speculations about an "inflationary multiverse". From a point of view of phenomenology, the inflationary universe scenario has been very successful. However, the scenario suffers from some conceptual problems, and thus it does not (yet) have the status of a solid theory. There are alternative ideas for the evolution of the very early universe which do not involve inflation but which agree with most current cosmological observations as well as inflation does. In this lecture I will outline the conceptual problems of inflation and introduce two alternative pictures - the "matter bounce" and "string gas cosmology", the latter being a realization of the "emergent universe" scenario based on some key principles of superstring theory. I will demonstrate that these two alternative pictures lead to the same predictions for the power spectrum of the observed large-scale structure and for the angular power spectrum of cosmic microwave background anisotropies as the inflationary scenario, and I will mention predictions for future observations with which the three scenarios can be observationally teased apart.

  4. Gravitino condensates in the early universe and inflation

    Directory of Open Access Journals (Sweden)

    Mavromatos Nick E.

    2015-01-01

    Full Text Available We review work on the formation of gravitino condensates via the super-Higgs effect in the early Universe. This is a scenario for both inflating the early universe and breaking local super-symmetry (supergravity, entirely independent of any coupling to external matter. The goldstino mode associated with the breaking of (global super-symmetry is “eaten” by the gravitino field, which becomes massive (via its own vacuum condensation and breaks the local supersymmetry (supergravity dynamically. The most natural association of gravitino condensates with inflation proceeds in an indirect way, via a Starobinsky-inflation-type phase. The higher-order curvature corrections of the (quantum effective action of gravitino condensates induced by integrating out massive gravitino degrees of freedom in a curved space-time background, in the broken-supergravity phase, are responsible for inducing a scalar mode which inflates the Universe. The scenario is in agreement with Planck data phenomenology in a natural and phenomenologically-relevant range of parameters, namely Grand-Unified-Theory values for the super-symmetry breaking energy scale and dynamically-induced gravitino mass.

  5. Brane gases in the early universe: thermodynamics and cosmology

    CERN Document Server

    Easther, R; Jackson, M G; Kabat, D; Easther, Richard; Greene, Brian R.; Jackson, Mark G.; Kabat, Daniel

    2004-01-01

    We consider the thermodynamic and cosmological properties of brane gases in the early universe. Working in the low energy limit of M-theory we assume the universe is a homogeneous but anisotropic 10-torus containing wrapped 2-branes and a supergravity gas. We describe the thermodynamics of this system and estimate a Hagedorn temperature associated with excitations on the branes. We investigate the cross-section for production of branes from the thermal bath and derive Boltzmann equations governing the number of wrapped branes. A brane gas may lead to decompactification of three spatial dimensions. To investigate this possibility we adopt initial conditions in which we fix the volume of the torus but otherwise assume all states are equally likely. We solve the Einstein-Boltzmann equations numerically, to determine the number of dimensions with no wrapped branes at late times; these unwrapped dimensions are expected to decompactify. Finally we consider holographic bounds on the initial volume, and find that for...

  6. Entropy of gravitons produced in the early Universe

    CERN Document Server

    Kiefer, C; Starobinsky, A A

    2000-01-01

    Gravitons produced from quantum vacuum fluctuations during an inflationary stage in the early Universe have zero entropy as far as they reflect the time evolution (squeezing) of a pure state, their large occupation number notwithstanding. A non-zero entropy of the gravitons (classical gravitational waves (GW) after decoherence) can be obtained through coarse graining. The latter has to be physically justified {\\it and} should not contradict observational constraints. We propose two ways of coarse graining for which the fixed temporal phase of each Fourier mode of the GW background still remains observable: one based on quantum entanglement, and another one following from the presence of a secondary GW background. The proposals are shown to be mutually consistent. They lead to the result that the entropy of the primordial GW background is significantly smaller than it was thought earlier. The difference can be ascribed to the information about the regular (inflationary) initial state of the Universe which is s...

  7. Thermodynamics of viscous Matter and Radiation in Early Universe

    CERN Document Server

    Tawfik, A

    2011-01-01

    Assuming that the background geometry is filled with free gas consisting of matter and radiation and no phase transitions being occurred in the early Universe, we discuss the thermodynamics of this {\\it closed} system using classical approaches. We find that essential cosmological quantities, such as Hubble parameter $H$, scale factor $a$ and curvature parameter $k$, can be derived from this simple model, which on one hand fulfills and entirely obeys the laws of thermodynamics. On the other hand, the results are compatible with the Friedmann-Lemaitre-Robertson-Walker model and the Einstein field equations. The inclusion of finite bulk viscosity coefficient derives to important changes in all these cosmological quantities. Accordingly, our picture about the evolution of the Universe and its astrophysical consequences seems to be a subject of a radical revision. We find that $k$ strongly depends on the thermodynamics of background matter. The time scale, at which negative curvature might take place, depends on ...

  8. Numerical Relativity as a tool for studying the Early Universe

    CERN Document Server

    Garrison, David

    2012-01-01

    Numerical simulations are becoming a more effective tool for conducting detailed investigations into the evolution of our universe. In this article, we show how the framework of numerical relativity can be used for studying cosmological models. The author is working to develop a large-scale simulation of the dynamical processes in the early universe. These take into account interactions of dark matter, scalar perturbations, gravitational waves, magnetic fields and a dynamic plasma. The code described in this report is a GRMHD code based on the Cactus framework and is structured to utilize one of several different differencing methods chosen at run-time. It is being developed and tested on the Texas Learning and Computation Center's Xanadu Cluster.

  9. Thermodynamics of viscous matter and radiation in the early universe

    Science.gov (United States)

    Tawfik, A.; Magdy, H.

    2012-05-01

    Assuming that the background geometry is filled with free gas consisting of matter and radiation and no phase transitions being occurred in the early Universe, we discuss the thermodynamics of this {\\it closed} system using classical approaches. We find that essential cosmological quantities, such as Hubble parameter $H$, scale factor $a$ and curvature parameter $k$, can be derived from this simple model, which on one hand fulfills and entirely obeys the laws of thermodynamics. On the other hand, the results are compatible with the Friedmann-Lemaitre-Robertson-Walker model and the Einstein field equations. The inclusion of finite bulk viscosity coefficient derives to important changes in all these cosmological quantities. Accordingly, our picture about the evolution of the Universe and its astrophysical consequences seems to be a subject of a radical revision. We find that $k$ strongly depends on the thermodynamics of background matter. The time scale, at which negative curvature might take place, depends on the relation between the matter content and the total energy. Using quantum and statistical approaches, we assume that the size of the Universe is given by the volume occupied one particle and one photon. Different types of their interactions are taken into account. Expressions for $H$ and $a$ are introduced. Therefore, the expansion of the Universe turns to be accessible.

  10. Generation of hypermagnetic helicity and leptogenesis in the early Universe

    Science.gov (United States)

    Semikoz, V. B.; Smirnov, A. Yu.; Sokoloff, D. D.

    2016-05-01

    We study hypermagnetic helicity and lepton asymmetry evolution in the plasma of the early Universe before the electroweak phase transition accounting for chirality flip processes via inverse Higgs decays and sphaleron transitions which violate the left lepton number and wash out the baryon asymmetry of the Universe (BAU). In the scenario where the right electron asymmetry supports the BAU alone through the conservation law B /3 -Le R=const at temperatures T >TRL≃10 TeV , the following Universe cooling leads to the production of a nonzero left lepton (electrons and neutrinos) asymmetry. This is due to the Higgs decays becoming faster when entering the equilibrium at T =TRL, with the Universe expansion, ΓRL˜T >H ˜T2 , resulting in the parallel evolution of the right and left electron asymmetries at T

  11. Generation of hypermagnetic helicity and leptogenesis in early universe

    CERN Document Server

    Semikoz, V B; Sokoloff, D D

    2016-01-01

    We study hypermagnetic helicity and lepton asymmetry evolution in plasma of the early Universe before the electroweak phase transition (EWPT) accounting for chirality flip processes via inverse Higgs decays and sphaleron transitions which violate the left lepton number and wash out the baryon asymmetry of the Universe (BAU). In the scenario where the right electron asymmetry supports the BAU alone through the conservation law $B/3 - L_{eR}=const$ at temperatures $T>T_{RL}\\simeq 10~TeV$ the following universe cooling leads to the production of a non-zero left lepton (electrons and neutrinos) asymmetry. This is due to the Higgs decays becoming more faster when entering the equilibrium at $T=T_{RL}$ with the universe expansion, $\\Gamma_{RL}\\sim T> H\\sim T^2$ , resulting in the parallel evolution of the right and the left electron asymmetries at $T

  12. Hypermagnetic helicity evolution in early universe: leptogenesis and hypermagnetic diffusion

    CERN Document Server

    Semikoz, V B; Sokoloff, D D

    2013-01-01

    We study hypermagnetic helicity and lepton asymmetry evolution in plasma of the early Universe before the electroweak phase transition (EWPT) accounting for chirality flip processes via inverse Higgs decays and sphaleron transitions which violate the left lepton number and wash out the baryon asymmetry of the Universe (BAU). In the scenario where the right electron asymmetry supports the BAU alone through the conservation law $B/3 - L_{eR}=const$ at temperatures $T>T_{RL}\\simeq 10 TeV$ the following universe cooling leads to the production of a non-zero left lepton (electrons and neutrinos) asymmetry. This is due to the Higgs decays becoming more faster when entering the equilibrium at $T=T_{RL}$ with the universe expansion, $\\Gamma_{RL}\\sim T> H\\sim T^2$, resulting in the parallel evolution of both the right and the left electron asymmetries at $T

  13. The Origin of Dust in the Early Universe

    Science.gov (United States)

    Dwek, Eli

    2011-01-01

    In this talk I will describe the origin of dust in the early universe. I will be presenting observations of the spectral energy distribution of the galaxy J1148+5251, and present estimates of the dust mass in this high redshift (z=6.4) object. I will then discuss the origin of this dust, and the role of SN and AGB stars as dust sources, and the effect of SNRs on the destruction of dust in the interstellar medium of this galaxy.

  14. Early universe cosmology and tests of fundamental physics

    Energy Technology Data Exchange (ETDEWEB)

    Andreas Albrecht, Joshua A. Frieman and Mark Trodden

    2002-03-04

    This is the report of the Working Group on Early Universe Cosmology and tests of Fundamental Physics, group P4.8 of the of the Snowmass 2001 conference. Here we summarize the impressive array of advances that have taken place in this field, and identify opportunities for even greater progress in the future. Topics include Dark Energy, Cosmic Acceleration, Inflation, Phase Transitions, Baryogenesis, and String/M-theory Cosmology. The introductory section gives an executive summary with six key open questions on which we can expect to make significant progress.

  15. Resonant Production of Sterile Neutrinos in the Early Universe

    Science.gov (United States)

    Gilbert, Lauren; Grohs, Evan; Fuller, George M.

    2016-06-01

    This study examines the cosmological impacts of a light resonantly produced sterile neutrino in the early universe. Such a neutrino could be produced through lepton number-driven Mikheyev-Smirnov-Wolfenstein (MSW) conversion of active neutrinos around big bang nucleosynthesis (BBN), resulting in a non-thermal spectrum of both sterile and electron neutrinos. During BBN, the neutron-proton ratio depends sensitively on the electron neutrino flux. If electron neutrinos are being converted to sterile neutrinos, this makes the n/p ratio a probe of possible new physics. We use observations of primordial Yp and D/H to place limits on this process.

  16. Early Universe Constraints on Time Variation of Fundamental Constants

    CERN Document Server

    Landau, Susana J; Scoccola, Claudia G; Vucetich, Hector

    2008-01-01

    We study the time variation of fundamental constants in the early Universe. Using data from primordial light nuclei abundances, CMB and the 2dFGRS power spectrum, we put constraints on the time variation of the fine structure constant $\\alpha$, and the Higgs vacuum expectation value $$ without assuming any theoretical framework. A variation in $$ leads to a variation in the electron mass, among other effects. Along the same line, we study the variation of $\\alpha$ and the electron mass $m_e$. In a purely phenomenological fashion, we derive a relationship between both variations.

  17. On the origin and early diagenesis of early Triassic carbonate mud (Dolomites, Italy)

    Science.gov (United States)

    Preto, Nereo; Westphal, Hildegard; Birgel, Daniel; Carampin, Raul; Dal Corso, Jacopo; Gattolin, Giovanni; Montinaro, Alice; Peckmann, Jörn

    2015-04-01

    The earliest Triassic (early Induan) deposits of the Italian Southern Alps are shallow water oolites, and lime-mudstone formed in an open shelf (mid to outer carbonate ramp) sedimentary environment, deposited after the end-Permian extinction that killed all carbonate producers. The origin of these lime-mudstones is thus enigmatic. We used a multidisciplinary petrographic and geochemical approach to identify the origin and early diagenesis of early Triassic lime-mudstones of the Dolomites (Northern Italy). This fine carbonate is made of pitted crystals of microsparite, ~ 25 μm in diameter, exhibiting zonation both in fluorescence and cathodoluminescence. Field and standard petrographic observations exclude an origin from fragmentation or abrasion of carbonate grains. Strontium content, measured in-situ with electron microprobe, has a bimodal distribution with values locally as high as > 4000 ppm. Lipid biomarker analysis revealed molecular fossils of bacteria (terminally-branched alkanes, hopanes, and scarce methylhopanes) along with compounds of low source specificity (n-alkanes), whereas biomarkers of algae (steranes) were not detected. This suggests that, differently from modern Caribbean shelfs, this fine carbonate did not originate from the disgregation of green algae. A Pristane to Phytane ratio < 1 also suggests deposition under anoxic conditions, in agreement with the known status of "superanoxia" of earliest Triassic oceans. Overall, our observations suggest an aragonitic mineralogy of the carbonate mud, followed by calcite replacement and cementation in the marine burial early diagenetic environment. Our data strongly suggest that the early Triassic carbonate mud of the Dolomites was precipitated in the water column, similarly to the modern whitings of the Bahamas, and then settled on a shelf bottom below wave base. Our study shows that these lime-mudstones contain aragonite replaced by calcite and calcite cement, in variable proportions. The δ13C of

  18. The Transient High Energy Sky and Early Universe Surveyor (THESEUS)

    Science.gov (United States)

    Amati, Lorenzo; O'Brien, Paul T.; Götz, Diego

    2016-07-01

    The Transient High Energy Sky and Early Universe Surveyor (THESEUS) is a mission concept under development by a large international collaboration aimed at exploiting gamma-ray bursts for investigating the early Universe. The main scientific objectives of THESEUS include: investigating the star formation rate and metallicity evolution of the ISM and IGM up to redshift 9-10, detecting the first generation (pop III) of stars, studying the sources and physics of re-ionization, detecting the faint end of galaxies luminosity function. These goals will be achieved through a unique combination of instruments allowing GRB detection and arcmin localization over a broad FOV (more than 1sr) and an energy band extending from several MeVs down to 0.3 keV with unprecedented sensitivity, as well as on-board prompt (few minutes) follow-up with a 0.6m class IR telescope with both imaging and spectroscopic capabilities. Such instrumentation will also allow THESEUS to unveil and study the population of soft and sub-energetic GRBs, and, more in general, to perform monitoring and survey of the X-ray sky with unprecedented sensitivity.

  19. Quark-Hadron Phase Transitions in Viscous Early Universe

    CERN Document Server

    Tawfik, A

    2011-01-01

    Based on hot big bang theory, the cosmological matter is conjectured to undergo QCD phase transition(s) to hadrons, when the universe was about $1-10 \\mu$s old. In the present work, we study the quark-hadron phase transition, by taking into account the effect of the bulk viscosity. We analyze the evolution of the quantities relevant for the physical description of the early universe, namely, the energy density $\\rho$, temperature $T$, Hubble parameter $H$ and scale factor $a$ before, during and after the phase transition. To study the cosmological dynamics and the time evolution we use both analytical and numerical methods. By assuming that the phase transition may be described by an effective nucleation theory (prompt {\\it first-order} phase transition), we also consider the case where the universe evolved through a mixed phase with a small initial supercooling and monotonically growing hadronic bubbles. The numerical estimation of the cosmological parameters, $a$ and $H$ for instance, makes it clear that th...

  20. A universal model for nanoporous carbon supercapacitors applicable to diverse pore regimes, carbon materials, and electrolytes.

    Science.gov (United States)

    Huang, Jingsong; Sumpter, Bobby G; Meunier, Vincent

    2008-01-01

    Supercapacitors, commonly called electric double-layer capacitors (EDLCs), are emerging as a novel type of energy-storage device with the potential to substitute batteries in applications that require high power densities. In response to the latest experimental breakthrough in nanoporous carbon supercapacitors, we propose a heuristic theoretical model that takes pore curvature into account as a replacement for the EDLC model, which is based on a traditional parallel-plate capacitor. When the pore size is in the mesopore regime (2-50 nm), counterions enter mesoporous carbon materials and approach the pore wall to form an electric double-cylinder capacitor (EDCC); in the micropore regime (50 nm) at which pores are large enough so that pore curvature is no longer significant, the EDCC model can be reduced naturally to the EDLC model. We present density functional theory calculations and detailed analyses of available experimental data in various pore regimes, which show the significant effects of pore curvature on the supercapacitor properties of nanoporous carbon materials. It is shown that the EDCC/EWCC model is universal for carbon supercapacitors with diverse carbon materials, including activated carbon materials, template carbon materials, and novel carbide-derived carbon materials, and with diverse electrolytes, including organic electrolytes, such as tetraethylammonium tetrafluoroborate (TEABF(4)) and tetraethylammonium methylsulfonate (TEAMS) in acetonitrile, aqueous H(2)SO(4) and KOH electrolytes, and even an ionic liquid electrolyte, such as 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMI-TFSI). The EDCC/EWCC model allows the supercapacitor properties to be correlated with pore size, specific surface area, Debye length, electrolyte concentration and dielectric constant, and solute ion size It may lend support for the systematic optimization of the properties of carbon supercapacitors through experiments. On the basis of the insight

  1. Blast from the Past Gives Clues About Early Universe

    Science.gov (United States)

    2009-10-01

    Astronomers using the National Science Foundation's Very Large Array (VLA) radio telescope have gained tantalizing insights into the nature of the most distant object ever observed in the Universe -- a gigantic stellar explosion known as a Gamma Ray Burst (GRB). The explosion was detected on April 23 by NASA's Swift satellite, and scientists soon realized that it was more than 13 billion light-years from Earth. It represents an event that occurred 630 million years after the Big Bang, when the Universe was only four percent of its current age of 13.7 billion years. This explosion provides an unprecedented look at an era when the Universe was very young and also was undergoing drastic changes. The primal cosmic darkness was being pierced by the light of the first stars and the first galaxies were beginning to form. The star that exploded in this event was a member of one of these earliest generations of stars," said Dale Frail of the National Radio Astronomy Observatory. Astronomers turned telescopes from around the world to study the blast, dubbed GRB 090423. The VLA first looked for the object the day after the discovery, detected the first radio waves from the blast a week later, then recorded changes in the object until it faded from view more than two months later. "It's important to study these explosions with many kinds of telescopes. Our research team combined data from the VLA with data from X-ray and infrared telescopes to piece together some of the physical conditions of the blast," said Derek Fox of Pennsylvania State University. "The result is a unique look into the very early Universe that we couldn't have gotten any other way," he added. The scientists concluded that the explosion was more energetic than most GRBs, was a nearly-spherical blast, and that it expanded into a tenuous and relatively uniform gaseous medium surrounding the star. Astronomers suspect that the very first stars in the Universe were very different -- brighter, hotter, and more

  2. Follow the Carbon: Isotopic Labeling Studies of Early Earth Aerosol.

    Science.gov (United States)

    Hicks, Raea K; Day, Douglas A; Jimenez, Jose L; Tolbert, Margaret A

    2016-11-01

    Despite the faint young Sun, early Earth might have been kept warm by an atmosphere containing the greenhouse gases CH4 and CO2 in mixing ratios higher than those found on Earth today. Laboratory and modeling studies suggest that an atmosphere containing these trace gases could lead to the formation of organic aerosol haze due to UV photochemistry. Chemical mechanisms proposed to explain haze formation rely on CH4 as the source of carbon and treat CO2 as a source of oxygen only, but this has not previously been verified experimentally. In the present work, we use isotopically labeled precursor gases and unit-mass resolution (UMR) and high-resolution (HR) aerosol mass spectrometry to examine the sources of carbon and oxygen to photochemical aerosol formed in a CH4/CO2/N2 atmosphere. UMR results suggest that CH4 contributes 70-100% of carbon in the aerosol, while HR results constrain the value from 94% to 100%. We also confirm that CO2 contributes approximately 10% of the total mass to the aerosol as oxygen. These results have implications for the geochemical interpretations of inclusions found in Archean rocks on Earth and for the astrobiological potential of other planetary atmospheres. Key Words: Atmosphere-Early Earth-Planetary atmospheres-Carbon dioxide-Methane. Astrobiology 16, 822-830.

  3. Quartic Chameleons: Safely Scale-Free in the Early Universe

    CERN Document Server

    Miller, Carisa

    2016-01-01

    In chameleon gravity, there exists a light scalar field that couples to the trace of the stress-energy tensor in such a way that its mass depends on the ambient matter density, and the field is screened in local, high-density environments. Recently it was shown that, for the runaway potentials commonly considered in chameleon theories, the field's coupling to matter and the hierarchy of scales between Standard Model particles and the energy scale of such potentials result in catastrophic effects in the early Universe when these particles become nonrelativistic. Perturbations with trans-Planckian energies are excited, and the theory suffers a breakdown in calculability at the relatively low temperatures of Big Bang Nucleosynthesis. We consider a chameleon field in a quartic potential and show that the scale-free nature of this potential allows the chameleon to avoid many of the problems encountered by runaway potentials. Following inflation, the chameleon field oscillates around the minimum of its effective po...

  4. Probing early-universe phase transitions with CMB spectral distortions

    Science.gov (United States)

    Amin, Mustafa A.; Grin, Daniel

    2014-10-01

    Global, symmetry-breaking phase transitions in the early universe can generate scaling seed networks which lead to metric perturbations. The acoustic waves in the photon-baryon plasma sourced by these metric perturbations, when Silk damped, generate spectral distortions of the cosmic microwave background (CMB). In this work, the chemical potential distortion (μ ) due to scaling seed networks is computed and the accompanying Compton y -type distortion is estimated. The specific model of choice is the O (N ) nonlinear σ -model for N ≫1 , but the results remain the same order of magnitude for other scaling seeds. If CMB anisotropy constraints to the O (N ) model are saturated, the resulting chemical potential distortion μ ≲2 ×1 0-9 .

  5. Probing early-universe phase transitions with CMB spectral distortions

    CERN Document Server

    Amin, Mustafa A

    2014-01-01

    Global, symmetry-breaking phase transitions in the early universe can generate scaling seed networks which lead to metric perturbations. The acoustic waves in the photon-baryon plasma sourced by these metric perturbations, when Silk damped, generate spectral distortions of the cosmic microwave background (CMB). In this work, the chemical potential distortion ($\\mu$) due to scaling seed networks is computed and the accompanying Compton $y$-type distortion is estimated. The specific model of choice is the $O(N)$ nonlinear $\\sigma$-model for $N\\gg 1$, but the results remain the same order of magnitude for other scaling seeds. If CMB anisotropy constraints to the $O(N)$ model are saturated, the resulting chemical potential distortion $\\mu \\lesssim 2\\times 10^{-9}$.

  6. Primordial Black Holes from Supersymmetry in the Early Universe

    Science.gov (United States)

    Cotner, Eric; Kusenko, Alexander

    2017-07-01

    Supersymmetric extensions of the standard model generically predict that in the early Universe a scalar condensate can form and fragment into Q balls before decaying. If the Q balls dominate the energy density for some period of time, the relatively large fluctuations in their number density can lead to formation of primordial black holes (PBH). Other scalar fields, unrelated to supersymmetry, can play a similar role. For a general charged scalar field, this robust mechanism can generate black holes over the entire mass range allowed by observational constraints, with a sufficient abundance to account for all dark matter in some parameter ranges. In the case of supersymmetry the mass range is limited from above by 1 023 g . We also comment on the role that topological defects can play for PBH formation in a similar fashion.

  7. On Effective Degrees of Freedom in the Early Universe

    CERN Document Server

    Husdal, Lars

    2016-01-01

    We explore the effective degrees of freedom in the early Universe, from before the electroweak scale at a few femtoseconds after the Big Bang, until the last positrons disappeared a few minutes later. We first look at the established concepts of effective degrees of freedom for energy density, pressure and entropy density, and introduce effective degrees of freedom for number density as well. We discuss what happens with particle species as their temperature cools down from relativistic to semi- and non-relativistic temperatures, and then annihilates completely. This will affect the pressure as well as the entropy per particle. We also look at the transition from a quark-gluon plasma to a hadron gas. Using a list a known hadrons, we use a "cross-over" temperature of 214 MeV where the effective degrees of freedom for a quark-gluon plasma equals that of a hadron gas.

  8. The early universe: facts and fiction (astronomy and astrophysics library)

    CERN Document Server

    Börner, Gerhard

    2013-01-01

    This fourth edition of Börner's "The Early Universe" is practically a new book, not just updated version. In particular, it is now organized so as to make it more useful as a textbook. And problem sections are also added. In the centre are the connections between particle physics and cosmology: The standard model, some basic implications of quantum field theory and the questions of structure formation. Special emphasis is given to the observed anisotropies of the cosmic microwave background and the consequences drawn for cosmology and for the structure formation models. Nuclear and particle physicists and astrophysicists, researchers and teachers as well as graduate students will welcome this new edition of a classic text and reference.

  9. Parametric Resonance in the Early Universe - A Fitting Analysis

    CERN Document Server

    Figueroa, Daniel G.

    2017-01-01

    Particle production via parametric resonance in the early Universe, is a non-perturbative, non-linear and out-of-equilibrium phenomenon. Although it is a well studied topic, whenever a new scenario exhibits parametric resonance, a full re-analysis is normally required. To avoid this tedious task, many works present often only a simplified linear treatment of the problem. In order to surpass this circumstance in the future, we provide a fitting analysis of parametric resonance through all its relevant stages: initial linear growth, non-linear evolution, and relaxation towards equilibrium. Using lattice simulations in an expanding grid in $3+1$ dimensions, we parametrise the dynamics' outcome scanning over the relevant ingredients: role of the oscillatory field, particle coupling strength, initial conditions, and background expansion rate. We emphasise the inaccuracy of the linear calculation of the decay time of the oscillatory field, and propose a more appropriate definition of this scale based on the subsequ...

  10. On Effective Degrees of Freedom in the Early Universe

    Directory of Open Access Journals (Sweden)

    Lars Husdal

    2016-12-01

    Full Text Available We explore the effective degrees of freedom in the early Universe, from before the electroweak scale at a few femtoseconds after the Big Bang until the last positrons disappeared a few minutes later. We look at the established concepts of effective degrees of freedom for energy density, pressure, and entropy density, and introduce effective degrees of freedom for number density as well. We discuss what happens with particle species as their temperature cools down from relativistic to semi- and non-relativistic temperatures, and then annihilates completely. This will affect the pressure and the entropy per particle. We also look at the transition from a quark-gluon plasma to a hadron gas. Using a list a known hadrons, we use a “cross-over” temperature of 214 MeV, where the effective degrees of freedom for a quark-gluon plasma equals that of a hadron gas.

  11. Mutated Hilltop Inflation : A Natural Choice for Early Universe

    CERN Document Server

    Pal, Barun Kumar; Basu, B

    2009-01-01

    We propose a model of inflation with a suitable potential for a single scalar field which falls in the wide class of hilltop inflation. We derive the analytical expressions for most of the physical quantities related to inflation and show that all of them represent the true behavior as required from a model of inflation. We further subject the results to observational verification by formulating the theory of perturbations based on our model followed by an estimation for the values of those observable parameters. Our model is found to be in excellent agreement with observational data. Thus, the features related to the model leads us to infer that this type of hilltop inflation may be a natural choice for explaining the early universe.

  12. PhD Thesis: String theory in the early universe

    CERN Document Server

    Gwyn, Rhiannon

    2009-01-01

    The intersection of string theory with cosmology is unavoidable in the early universe, and its exploration may shine light on both fields. In this thesis, three papers at this intersection are presented and reviewed, with the aim of providing a thorough and pedagogical guide to their results. First, we address the longstanding problem of finding a string theory realisation of the axion. Using warped compactifications in heterotic string theory, we show that the axion decay constant can be lowered to acceptable values by the warp factor. Next, we move to the subject of cosmic strings, whose network evolution could have important consequences for astrophysics and cosmology. In particular, there are quantitative differences between cosmic superstring networks and GUT cosmic string networks. We investigate the properties of cosmic superstring networks in warped backgrounds, giving the tension and properties of three-string junctions in these backgrounds. Finally, we examine the possibility that cosmic strings in ...

  13. Thermal Production of Axinos in the Early Universe

    CERN Document Server

    Brandenburg, A; Brandenburg, Arnd; Steffen, Frank Daniel

    2004-01-01

    We compute the thermal axino production rate in supersymmetric QCD to leading order in the gauge coupling. Using hard thermal loop resummation and the Braaten-Yuan prescription, we obtain a finite result in a gauge-invariant way, which takes into account Debye screening in the hot quark-gluon-squark-gluino plasma. The relic axino density from thermal reactions in the early Universe is evaluated assuming the axino is the lightest supersymmetric particle and stable due to R-parity conservation. From the comparison with the WMAP results, we find that axinos could provide the dominant part of cold dark matter, for example, for an axino mass of 100 keV and a reheating temperature of 10^6 GeV.

  14. Quadrupole association and dissociation of hydrogen in the early Universe

    Science.gov (United States)

    Forrey, Robert C.

    2016-10-01

    Radiative association and photodissociation rates are calculated for quadrupole transitions of H2. A complete set of bound and unbound states are included in a self-consistent master equation to obtain steady-state concentrations for a dilute system of hydrogen atoms and molecules. Phenomenological rate constants computed from the steady-state concentrations satisfy detailed balance for any combination of matter and radiation temperature. Simple formulas are derived for expressing the steady-state distributions in terms of equilibrium distributions. The rate constant for radiative association is found to be generally small for all temperature combinations. The photodissociation rate constant for quadrupole transitions is found to dominate the rate constants for other H2 photodestruction mechanisms for {T}{{R}} ≤slant 3000 K. Implications for the formation and destruction of H2 in the early Universe are discussed.

  15. Quadrupole association and dissociation of hydrogen in the early Universe

    CERN Document Server

    Forrey, Robert C

    2016-01-01

    Radiative association and photodissociation rates are calculated for quadrupole transitions of H2. A complete set of bound and unbound states are included in a self-consistent master equation to obtain steady-state concentrations for a dilute system of hydrogen atoms and molecules. Phenomenological rate constants computed from the steady-state concentrations satisfy detailed balance for any combination of matter and radiation temperature. Simple formulas are derived for expressing the steady-state distributions in terms of equilibrium distributions. The rate constant for radiative association is found to be generally small for all temperature combinations. The photodissociation rate constant for quadrupole transitions is found to dominate the rate constants for other H2 photodestruction mechanisms for radiation temperatures less than or equal to 3000 K. Implications for the formation and destruction of H2 in the early universe are discussed.

  16. Primordial Black Holes from Supersymmetry in the Early Universe.

    Science.gov (United States)

    Cotner, Eric; Kusenko, Alexander

    2017-07-21

    Supersymmetric extensions of the standard model generically predict that in the early Universe a scalar condensate can form and fragment into Q balls before decaying. If the Q balls dominate the energy density for some period of time, the relatively large fluctuations in their number density can lead to formation of primordial black holes (PBH). Other scalar fields, unrelated to supersymmetry, can play a similar role. For a general charged scalar field, this robust mechanism can generate black holes over the entire mass range allowed by observational constraints, with a sufficient abundance to account for all dark matter in some parameter ranges. In the case of supersymmetry the mass range is limited from above by 10^{23}  g. We also comment on the role that topological defects can play for PBH formation in a similar fashion.

  17. Magnetic fields and chiral asymmetry in the early hot universe

    CERN Document Server

    Sidorenko, Maxim; Shtanov, Yuri

    2016-01-01

    In this paper, we study analytically the process of external generation and subsequent free evolution of the lepton chiral asymmetry and helical magnetic fields in the early hot universe. This process is known to be affected by the Abelian anomaly of the electroweak gauge interactions. As a consequence, chiral asymmetry in the fermion distribution generates magnetic fields of non-zero helicity, and vice versa. We take into account the presence of thermal bath, which serves as a seed for the development of instability in magnetic field in the presence of externally generated lepton chiral asymmetry. The developed helical magnetic field and lepton chiral asymmetry support each other, considerably prolonging their mutual existence, in the process of 'inverse cascade' transferring magnetic-field power from small to large spatial scales. For cosmologically interesting initial conditions, the chiral asymmetry and the energy density of helical magnetic field are shown to evolve by scaling laws, effectively depending...

  18. Early Universe Cosmology, Effective Supergravity, and Invariants of Algebraic Forms

    CERN Document Server

    Sinha, Kuver

    2015-01-01

    The presence of light scalars can have profound effects on early universe cosmology, influencing its thermal history as well as paradigms like inflation and baryogenesis. Effective supergravity provides a framework to make quantifiable, model-independent studies of these effects. The Riemanian curvature of the Kahler manifold spanned by scalars belonging to chiral superfields, evaluated along supersymmetry breaking directions, provides an order parameter (in the sense that it must necessarily take certain values) for phenomena as diverse as slow roll modular inflation, non-thermal cosmological histories, and the viability of Affleck-Dine baryogenesis. Within certain classes of UV completions, the order parameter for theories with $n$ scalar moduli is conjectured to be related to invariants of $n$-ary cubic forms (for example, for models with three moduli, the order parameter is given by the ring of invariants spanned by the Aronhold invariants). Within these completions, and under the caveats spelled out, thi...

  19. From universal to language-specific in early grammatical development.

    Science.gov (United States)

    Bowerman, M

    1994-10-29

    Attempts to explain children's grammatical development often assume a close initial match between units of meaning and units of form; for example, agents are said to map to sentence-subjects and actions to verbs. The meanings themselves, according to this view, are not influenced by language, but reflect children's universal non-linguistic way of understanding the world. This paper argues that, contrary to this position, meaning as it is expressed in children's early sentences is, from the beginning, organized on the basis of experience with the grammar and lexicon of a particular language. As a case in point, children learning English and Korean are shown to express meanings having to do with direct motion according to language-specific principles of semantic and grammatical structuring from the earliest stages of word combination.

  20. Spin and torsion in the very early universe

    Energy Technology Data Exchange (ETDEWEB)

    Baeuerle, G.G.A.; Haneveld, C.J. (Amsterdam Univ. (Netherlands). Inst. voor Theoretische Fysica)

    1983-09-01

    In the very early universe with temperature T between 10/sup 24/ K and 10/sup 32/ K the gravitational effect of torsion is dominant if particles with spin are sufficiently polarized. The source of the torsion is the spin density and the latter is usually described by a classical theory of Weyssenhoff and Raabe. In this article the spinning particles are described quantum mechanically, i.e. with a Dirac field and the spin density is defined as the source of the torsion. The macroscopic average of the spin density is obtained by the relativistic Wigner function formalism. The expression of the spin density, as derived in this article, is different from the classical one, except when both are zero.

  1. PROBING THE EARLY UNIVERSE WITH DEEP OBSERVATIONS AND LARGE SURVEYS

    Institute of Scientific and Technical Information of China (English)

    Zheng Wei

    2001-01-01

    Recent advances in astronomy have enabled scientists to reach the early universe to an unprecedented depth. With the new telescopes such as the Chandra, FUSE, and with the Sloan Digital Sky Survey (SDSS), we have gained critical insights into the “Origin of our Universe”, i.e. how the intergalactic medium evolves to form galaxies and quasars. SDSS has broken a ten-year barrier of z = 5 to reach the very early universe, with the discovery of five quasars at z ≥ 5. 0. The survey will find more than ten thousands of quasars, enabling us to carry out the most comprehensive classification of quasars. FUSE finds traces of the primordial matter at z ~ 3, which corresponds to hydrogen column density as low as 10-11 cm-2 and cannot be detected even with the largest optical telescope. The finding suggests that the intergalactic medium is an evolving and complex entity, and it is ionized mainly by the accumulated radiation from quasars. The Chandra telescope has taken a million second deep exposure of a selected region,reaching about twenty times deeper than ROSAT to a limiting flux of 5 × 1 0-17 ergs s-1 cm-2 in the 0. 5-2 keV band. The sources found so far can account for up to 90 % of the hard X-ray background field, and they consist of Seyfert-2 and normal galaxies at z < 1 and quasars at z < 4.5. In the near future, the Next Generation Space Telescope and others will reveal the first generation of baryonic objects after the Big Bang.

  2. Constraining anisotropic models of early Universe with WMAP9 data

    CERN Document Server

    Ramazanov, Sabir

    2013-01-01

    We constrain several models of the early Universe that predict statistical anisotropy of the CMB sky. We make use of WMAP9 maps deconvolved with beam asymmetries. As compared to previous releases of WMAP data, they do not exhibit the anomalously large quadrupole of the statistical anisotropy. This allows to strengthen limits on parameters of models established earlier in literature. In particular, the amplitude of the special quadrupole, whose direction is aligned with ecliptic poles, is now constrained as g_* =0.002 \\pm 0.041 at 95% CL (\\pm 0.020 at 68% CL). The upper limit is obtained on the total number of e-folds in anisotropic inflation with the Maxwellian term non-minimally coupled to the inflaton, namely N_{tot} Universe. The strongest constraint is obtained for spectator scenarios involving a long stage of subhorizon evolution after conformal rolling, which reads h^2 < 0.006 at 95% CL, in terms ...

  3. Cosmic microwave background and first molecules in the early universe

    Energy Technology Data Exchange (ETDEWEB)

    Signore, Monique [LERMA, Observatoire de Paris, Paris (France); Puy, Denis [University of Montpellier II, CNRS UMR 5024, GRAAL CC72, Montpellier (France)

    2009-01-15

    Besides the Hubble expansion of the universe, the main evidence in favor of the big-bang theory was the discovery, by Penzias and Wilson, of the cosmic microwave background (hereafter CMB) radiation. In 1990, the COBE satellite (Cosmic Background Explorer) revealed an accurate black-body behavior with a temperature around 2.7 K. Although the microwave background is very smooth, the COBE satellite did detect small variations - at the level of one part in 100 000 - in the temperature of the CMB from place to place in the sky. These ripples are caused by acoustic oscillations in the primordial plasma. While COBE was only sensitive to long-wavelength waves, the Wilkinson Microwave Anisotropy Probe (WMAP) - with its much higher resolution - reveals that the CMB temperature variations follow the distinctive pattern predicted by cosmological theory. Moreover, the existence of the microwave background allows cosmologists to deduce the conditions present in the early stages of the big bang and, in particular, helps to account for the chemistry of the universe. This report summarizes the latest measurements and studies of the CMB with the new calculations about the formation of primordial molecules. The PLANCK mission - planned to be launched in 2009 - is also presented. (orig.)

  4. Magnetic fields and chiral asymmetry in the early hot universe

    Science.gov (United States)

    Sydorenko, Maksym; Tomalak, Oleksandr; Shtanov, Yuri

    2016-10-01

    In this paper, we study analytically the process of external generation and subsequent free evolution of the lepton chiral asymmetry and helical magnetic fields in the early hot universe. This process is known to be affected by the Abelian anomaly of the electroweak gauge interactions. As a consequence, chiral asymmetry in the fermion distribution generates magnetic fields of non-zero helicity, and vice versa. We take into account the presence of thermal bath, which serves as a seed for the development of instability in magnetic field in the presence of externally generated lepton chiral asymmetry. The developed helical magnetic field and lepton chiral asymmetry support each other, considerably prolonging their mutual existence, in the process of `inverse cascade' transferring magnetic-field power from small to large spatial scales. For cosmologically interesting initial conditions, the chiral asymmetry and the energy density of helical magnetic field are shown to evolve by scaling laws, effectively depending on a single combined variable. In this case, the late-time asymptotics of the conformal chiral chemical potential reproduces the universal scaling law previously found in the literature for the system under consideration. This regime is terminated at lower temperatures because of scattering of electrons with chirality change, which exponentially washes out chiral asymmetry. We derive an expression for the termination temperature as a function of the chiral asymmetry and energy density of helical magnetic field.

  5. High Redshift Quasars and Star Formation in the Early Universe

    CERN Document Server

    Dietrich, M; Vestergaard, M; Wagner, S J

    2001-01-01

    In order to derive information on the star formation history in the early universe we observed 6 high-redshift (z=3.4) quasars in the near-infrared to measure the relative iron and \\mgii emission strengths. A detailed comparison of the resulting spectra with those of low-redshift quasars show essentially the same FeII/MgII emission ratios and very similar continuum and line spectral properties, indicating a lack of evolution of the relative iron to magnesium abundance of the gas since z=3.4 in bright quasars. On the basis of current chemical evolution scenarios of galaxies, where magnesium is produced in massive stars ending in type II SNe, while iron is formed predominantly in SNe of type Ia with a delay of ~1 Gyr and assuming as cosmological parameters H_o = 72 km/s Mpc, Omega_M = 0.3, and Omega_Lambda = 0.7$, we conclude that major star formation activity in the host galaxies of our z=3.4 quasars must have started already at an epoch corresponding to z_f ~= 10, when the age of the universe was less than 0....

  6. Cosmic Acceleration in the Early and Present Universe

    Science.gov (United States)

    Yamaguchi, Masahide

    Cosmic accelerations in the early and present Universe play essentially important roles to determine the evolution, structure, and destiny of the Universe. Therefore, to identify the origins of cosmic accelerations is one of the most ultimate goals of cosmology. In this award talk for the C. N. Yang Award, I introduced my achievements on this mystery. First of all, we gave a natural mechanism to cause chaotic inflation, which is the most natural inflation model but had never been realized in the context of realistic particle physics for almost twenty years. We introduced a Nambu-Goldstone-like shift symmetry, which is now recognized as a key feature to control the Planck-scale physics, and solved the long standing difficulties to realize chaotic inflation. Second, we found a generic relation (now called Suyama-Yamaguchi inequality) between higher order correlations of the curvature perturbations, which is quite useful to identify what fields are actually responsible for the origin of primordial fluctuation. Finally, we mention our proposal (now called k-essence) for the present cosmic acceleration.

  7. A Glimpse of the Very Early Universal Web

    Science.gov (United States)

    2001-05-01

    The VLT Maps Extremely Distant Galaxies Summary New, trailblazing observations with the ESO Very Large Telescope (VLT) at Paranal lend strong support to current computer models of the early universe: It is "spongy", with galaxies forming along filaments, like droplets along the strands of a spiders web. A group of astronomers at ESO and in Denmark [1] determined the distances to some very faint galaxies in the neighbourhood of a distant quasar. Plotting their positions in a three-dimensional map, they found that these objects are located within a narrow "filament", exactly as predicted by the present theories for the development of the first structures in the young universe . The objects are most likely "building blocks" from which galaxies and clusters of galaxies assemble. This observation shows a very useful way forward for the study of the early evolution of the universe and the emergence of structures soon after the Big Bang. At the same time, it provides yet another proof of the great power of the new class of giant optical telescopes for cosmological studies. PR Photo 19a/01 : Web-like structures in the young Universe (computer model). PR Photo 19b/01 : A group of objects at redshift 3.04 . PR Photo 19c/01 : Animated view of sky field and distant filament . PR Photo 19d/01 : The shape of the filament . PR Photo 19e/01 : Artist's impression of the very distant filament. PR Video Clip 04/01 : Video animation of the very distant filament. The computers are ahead of the telescopes For the past two decades cosmologists have been in the somewhat odd situation that their computers were "ahead" of their telescopes. The rapid evolution of powerful computer hardware and sophisticated software has provided theorists with the ability to build almost any sort of virtual universe they can imagine. Starting with different initial conditions just after the Big Bang, they can watch such fictional worlds evolve over billions of years in their supercomputers - and do so in a

  8. The Frequency of Supernovae in the Early Universe

    Science.gov (United States)

    Melinder, Jens

    Supernovae are cosmic explosions of cataclysmic proportion that signify the death of a star. While being interesting phenomena in their own right, their brightness also make them excellent probes of the early universe. Depending on the type of the progenitor star and the origin of the explosion different subjects can be investigated. In this dissertation the work I have done on the detection, characterisation and rate measurements of supernovae in the Stockholm VIMOS Supernova Search is presented. We have discovered 16 supernovae that exploded billions of years ago (or, equivalently, at high redshift, z). The observed brightness and colour evolution have been used to classify the supernovae into either thermonuclear (type Ia) or core collapse (type II) supernovae. The accuracy of the classification code is high, only about 5% of the supernovae are mistyped, similar to other codes of the same kind. By comparing the observed frequency of supernovae to simulations the underlying supernova rate at these high redshifts have been measured. The main result reported in this thesis is that the core collapse supernova rate at high redshift matches the rates estimated from looking at the star formation history of the universe, and agree well with previous studies. The rate of Ia supernovae at high redshift have been investigated by several projects, our results show a somewhat higher rate of Ia supernovae than expected. Proper estimates of the systematic errors of rate measurements are found to be very important. Furthermore, by using novel techniques for reducing and stacking images, we have obtained a galaxy sample containing approximately 50,000 galaxies. Photometric redshifts have been obtained for most of the galaxies, the resulting accuracy below z=1 is on the order of 10%. The galaxy sample has also been used to find high redshift sources, so called Lyman Break Galaxies, at z=3-5.

  9. Development of SED Camera for Quasars in Early Universe (SQUEAN)

    CERN Document Server

    Kim, Sanghyuk; Lee, Hye-In; Park, Woojin; Ji, Tae-Geun; Hyun, Minhee; Choi, Changsu; Im, Myungshin; Pak, Soojong

    2016-01-01

    We describe the characteristics and performance of a camera system, Spectral energy distribution Camera for Quasars in Early Universe (SQUEAN). It was developed to measure SEDs of high redshift quasar candidates (z $\\gtrsim$ 5) and other targets, e.g., young stellar objects, supernovae, and gamma-ray bursts, and to trace the time variability of SEDs of objects such as active galactic nuclei (AGNs). SQUEAN consists of an on-axis focal plane camera module, an auto-guiding system, and mechanical supporting structures. The science camera module is composed of a focal reducer, a customizable filter wheel, and a CCD camera on the focal plane. The filter wheel uses filter cartridges that can house filters with different shapes and sizes, enabling the filter wheel to hold twenty filters of 50 mm $\\times$ 50 mm size, ten filters of 86 mm $\\times$ 86 mm size, or many other combinations. The initial filter mask was applied to calibrate the filter wheel with high accuracy and we verified that the filter position is repea...

  10. PhD Thesis: String theory in the early universe

    Science.gov (United States)

    Gwyn, Rhiannon

    2009-11-01

    The intersection of string theory with cosmology is unavoidable in the early universe, and its exploration may shine light on both fields. In this thesis, three papers at this intersection are presented and reviewed, with the aim of providing a thorough and pedagogical guide to their results. First, we address the longstanding problem of finding a string theory realisation of the axion. Using warped compactifications in heterotic string theory, we show that the axion decay constant can be lowered to acceptable values by the warp factor. Next, we move to the subject of cosmic strings, whose network evolution could have important consequences for astrophysics and cosmology. In particular, there are quantitative differences between cosmic superstring networks and GUT cosmic string networks. We investigate the properties of cosmic superstring networks in warped backgrounds, giving the tension and properties of three-string junctions in these backgrounds. Finally, we examine the possibility that cosmic strings in heterotic string theory could be responsible for generating the galactic magnetic fields that seeded those observed today.

  11. Chameleons in the Early Universe: Kicks, Rebounds, and Particle Production

    CERN Document Server

    Erickcek, Adrienne L; Burrage, Clare; Huang, Zhiqi

    2013-01-01

    Chameleon gravity is a scalar-tensor theory that includes a non-minimal coupling between the scalar field and the matter fields and yet mimics general relativity in the Solar System. The scalar degree of freedom is hidden in high-density environments because the effective mass of the chameleon scalar depends on the trace of the stress-energy tensor. In the early Universe, when the trace of the matter stress-energy tensor is nearly zero, the chameleon is very light, and Hubble friction prevents it from reaching the minimum of its effective potential. Whenever a particle species becomes non-relativistic, however, the trace of the stress-energy tensor is temporarily nonzero, and the chameleon begins to roll. We show that these "kicks" to the chameleon field have catastrophic consequences for chameleon gravity. The velocity imparted to the chameleon by the kick is sufficiently large that the chameleon's mass changes rapidly as it slides past its potential minimum. This nonadiabatic evolution shatters the chameleo...

  12. Camera for QUasars in EArly uNiverse (CQUEAN)

    CERN Document Server

    Park, Won-Kee; Im, Myungshin; Choi, Changsu; Jeon, Yiseul; Chang, Seunghyuk; Jeong, Hyeonju; Lim, Juhee; Kim, Eunbin

    2012-01-01

    We describe the overall characteristics and the performance of an optical CCD camera system, Camera for QUasars in EArly uNiverse (CQUEAN), which is being used at the 2.1 m Otto Struve Telescope of the McDonald Observatory since 2010 August. CQUEAN was developed for follow-up imaging observations of red sources such as high redshift quasar candidates (z >= 5), Gamma Ray Bursts, brown dwarfs, and young stellar objects. For efficient observations of the red objects, CQUEAN has a science camera with a deep depletion CCD chip which boasts a higher quantum efficiency at 0.7 - 1.1 um than conventional CCD chips. The camera was developed in a short time scale (~ one year), and has been working reliably. By employing an auto-guiding system and a focal reducer to enhance the field of view on the classical Cassegrain focus, we achieve a stable guiding in 20 minute exposures, an imaging quality with FWHM >= 0.6" over the whole field (4.8' * 4.8'), and a limiting magnitude of z = 23.4 AB mag at 5-sigma with one hour tota...

  13. GRB Probes of the Early Universe with EXIST

    CERN Document Server

    Grindlay, Jonathan E

    2010-01-01

    With the Swift detection of GRB090423 at z = 8.2, it was confirmed that GRBs are now detectable at (significantly) larger redshifts than AGN, and so can indeed be used as probes of the Early Universe. The proposed Energetic X-ray Imaging Survey Telescope (EXIST) mission has been designed to detect and promptly measure redshifts and both soft X-ray (0.1 - 10 keV) and simultaneous nUV-nIR (0.3 - 2.3microns) imaging and spectra for GRBs out to redshifts z ~18, which encompasses (or even exceeds) current estimates for Pop III stars that are expected to be massive and possibly GRB sources. Scaling from Swift for the ~10X greater sensitivity of EXIST, more than 100 GRBs at z >=8 may be detected and would provide direct constraints on the formation and evolution of the first stars and galaxies. For GRBs at redshifts z >= 8, with Lyman breaks at greater than 1.12microns, spectra at resolution R = 30 or R = 3000 for afterglows with AB magnitudes brighter than 24 or 20 (respectively) within ~3000sec of trigger will dir...

  14. Development of SED Camera for Quasars in Early Universe (SQUEAN)

    Science.gov (United States)

    Kim, Sanghyuk; Jeon, Yiseul; Lee, Hye-In; Park, Woojin; Ji, Tae-Geun; Hyun, Minhee; Choi, Changsu; Im, Myungshin; Pak, Soojong

    2016-11-01

    We describe the characteristics and performance of a camera system, Spectral energy distribution Camera for Quasars in Early Universe (SQUEAN). It was developed to measure SEDs of high-redshift quasar candidates (z ≳ 5) and other targets, e.g., young stellar objects, supernovae, and gamma-ray bursts, and to trace the time variability of SEDs of objects such as active galactic nuclei (AGNs). SQUEAN consists of an on-axis focal plane camera module, an autoguiding system, and mechanical supporting structures. The science camera module is composed of a focal reducer, a customizable filter wheel, and a CCD camera on the focal plane. The filter wheel uses filter cartridges that can house filters with different shapes and sizes, enabling the filter wheel to hold 20 filters of 50 mm × 50 mm size, 10 filters of 86 mm × 86 mm size, or many other combinations. The initial filter mask was applied to calibrate the filter wheel with high accuracy, and we verified that the filter position is repeatable at much less than one pixel accuracy. We installed and tested 50 nm medium bandwidth filters of 600–1050 nm and other filters at the commissioning observation in 2015 February. We found that SQUEAN can reach limiting magnitudes of 23.3–25.3 AB mag at 5σ in a one-hour total integration time.

  15. Galaxies in the Early Universe characterized in absorption and emission

    CERN Document Server

    Krogager, Jens-Kristian

    2016-01-01

    Understanding how galaxies evolved from the early Universe through cosmic time is a fundamental part of modern astrophysics. In order to study this evolution it is important to sample the galaxies at various times in a consistent way through time. In regular luminosity selected samples, our analyses are biased towards the brightest galaxies at all times (as these are easier to observe and identify). A complementary method relies on the absorption imprint from neutral gas in galaxies, the so-called damped Ly-alpha absorbers (DLAs) seen towards distant bright objects. This thesis seeks to understand how the absorption selected galaxies relate to the emission selected galaxies by identifying the faint glow from the absorbing galaxies at redshift z~2. In the last Chapter, a study of the more evolved, massive galaxies is presented. These galaxies are observed to be a factor of 2 to 6 times smaller than local galaxies of similar masses. A new spectroscopically selected sample is presented and the increased precisio...

  16. Polar record of Early Jurassic massive carbon injection

    Science.gov (United States)

    Suan, Guillaume; Nikitenko, Boris L.; Rogov, Mikhail A.; Baudin, François; Spangenberg, Jorge E.; Knyazev, Valeriy G.; Glinskikh, Larisa A.; Goryacheva, Anna A.; Adatte, Thierry; Riding, James B.; Föllmi, Karl B.; Pittet, Bernard; Mattioli, Emanuela; Lécuyer, Christophe

    2011-12-01

    The Toarcian Oceanic Anoxic Event (T-OAE) (ca. 182 Myr, Early Jurassic) represents one of the best-recognized examples of greenhouse warming, decreased seawater oxygenation and mass extinction. The leading hypothesis to explain these changes is the massive injection of thermogenic or gas hydrate-derived 13C-depleted carbon into the atmosphere, resulting in a > 3 per mil negative carbon isotope excursion (CIE), accelerated nutrient input and dissolved oxygen consumption in the oceans. Nevertheless, the lack of a precisely dated record of the T-OAE outside low latitudes has led to considerable debate about both its temporal and spatial extent and hence concerning its underlying causes. Here we present new isotopic and lithological data from three precisely dated N Siberian sections, which demonstrate that mass extinction and onset of strong oxygen-deficiency occurred near synchronously in polar and most tropical sites and were intimately linked to the onset of a marked 6‰ negative CIE recorded by bulk organic carbon. Rock Eval pyrolysis data from Siberia and comparisons with low latitudes show that the CIE cannot be explained by the extent of stratification of the studied basins or changes in organic matter sourcing and suggest that the negative CIE reflects rapid 13C-depleted carbon injection to all exchangeable reservoirs. Sedimentological and palynological indicators show that the injection coincided with a change from cold (abundant glendonites and exotic boulder-sized clasts) to exceptionally warm conditions (dominance of the thermophyllic pollen genus Classopollis) in the Arctic, which likely triggered a rapid, possibly partly glacioeustatic sea-level rise. Comparisons with low latitude records reveal that warm climate conditions and poor marine oxygenation persisted in continental margins at least 600 kyr after the CIE, features that can be attributed to protracted and massive volcanic carbon dioxide degassing. Our data reveal that the T-OAE profoundly

  17. Topological Defects and Structures in the Early Universe

    Science.gov (United States)

    Zhu, Yong

    1997-08-01

    This thesis discusses the topological defects generated in the early universe and their contributions to cosmic structure formation. First, we investigate non-Gaussian isocurvature perturbations generated by the evolution of Goldstone modes during inflation. If a global symmetry is broken before inflation, the resulting Goldstone modes are disordered during inflation in a precise and predictable way. After inflation these Goldstone modes order themselves in a self-similar way, much as Goldstone modes in field ordering scenarios based on the Kibble mechanism. For (Hi2/Mpl2)~10- 6, through their gravitational interaction these Goldstone modes generate density perturbations of approximately the right magnitude to explain the cosmic microwave background (CMB) anisotropy and seed the structure seen in the universe today. In such a model non-Gaussian perturbations result because to lowest order density perturbations are sourced by products of Gaussian fields. We explore the issue of phase dispersion and conclude that this non-Gaussian model predicts Doppler peaks in the CMB anisotropy. Topological defects generated from quantum fluctuations during inflation are studied in chapter four. We present a calculation of the power spectrum generated in a classically symmetry-breaking O(N) scalar field through inflationary quantum fluctuations, using the large-N limit. The effective potential of the theory in de Sitter space is obtained from a gap equation which is exact at large N. Quantum fluctuations restore the O(N) symmetry in de Sitter space, but for the finite values of N of interest, there is symmetry breaking and phase ordering after inflation, described by the classical nonlinear sigma model. The scalar field power spectrum is obtained as a function of the scalar field self-coupling. In the second part of the thesis, we investigate non-Abelian topological worm-holes, obtained when winding number one texture field is coupled to Einstein gravity with a conserved global

  18. Pronounced carbonate deposition in the Early Triassic Dienerian substage: Who was the carbonate producer?

    Science.gov (United States)

    Horacek, Micha; Brandner, Rainer

    2014-05-01

    At the Late Permian Mass Extinction (LPME) most marine carbonate producers were heavily affected or even terminated. After the event in several sections a "boundary clay" was deposited and in the Griesbachian microbialites have been reported from many marine sections, however, without causing substantial thicknesses. The Dienerian in many Tethyan sections, though, is characterized by a huge increase in sedimentation rate due to the deposition of limestone mud with only minor amounts of siliciclastic input. This is in contrast to the still missing "usual" (skeletal) carbonate producers that have not yet re-appeared after the extinction, and also in contrast to a steeply and constantly rising marine Sr-isotope curve. To us this pattern indicates short timed intense post-extinction acidification in some areas causing a strong decrease of carbonate precipitation and thus resulting in the sedimentation of the boundary clay. Post-extinction low sedimentation rate supported the extensive growth of microbialites, thrombolites and stromatolites on seafloors in the photic zone, resulting in the photosynthetic uptake of bicarbonate ions which induced carbonate biomineralisation within the microbial mats probably during still prevailing acidic ocean condition. In the Dienerian the ocean water pH must have returned to non-acidic conditions again due to biotic and probably mainly microbial activity, resulting in a thriving and carbonate precipitating planctic microbial community producing huge amounts of microcrystalline carbonate mud. As some sections already in the Griesbachian feature substantial accumulations of carbonate mud layers, there acidification might have lasted only for a shorter period. Burial of the mainly microbial biomass probably also resulted in the positive 13C isotope curve trend from the Griesbachian to the Dienerian-Smithian boundary. Our interpretation identifies the (marine) microbial community as one of the important and THE biotic factor influencing

  19. Becoming the University: Early Presidential Discourses of Gordon Gee

    Science.gov (United States)

    Rishell, Michael W.

    2011-01-01

    The author explores Gordon Gee's career as a university president. There is a special focus on the journey Gee made between 1990, when he first became president of The Ohio State University, to 2007, when he returned to Ohio State for another term as university president ten years later. During this time away from Ohio State, he served as the…

  20. Genesis and evolution of dust in the early Universe

    Science.gov (United States)

    Gall, Christa

    2010-10-01

    The most fascinating aspect of studying dust is the fact that small dust particles of a few micrometer which we cannot see with our naked eyes are a fundamentally important component in a Universe whose dimension we hardly can imagine. Dust grains impact the evolution of the Universe in many ways. For example they are known as the main formation site of molecular hydrogen which acts as important coolant by the formation of stars similar to our Sun. Dust is essential for the formation of planets and plays an important role in the end stages of life of most stars. Large amounts of dust have been discovered in quasars (QSOs) at high redshift where the epoch of cosmic evolution was ! 1 Gyr, but the origin and evolution of these remains elusive. Supernovae (SNe) and asymptotic giant branch (AGB) stars have been contemplated as prime dust sources due to their potential ability of generating sufficiently high amounts of dust. Though AGB stars are in fact known as the main dust source in the present Universe, their partially (too) long lifetimes questions their significance as dust contributers in the early Universe. SNe are sufficiently short-lived, but there exists a discrepancy between observationally and theoretically ascertained dust yields. The principal aim of this thesis is to elucidate the astrophysical conditions required for generating these large amounts of dust in massive starburst galaxies and QSOs at high redshift. We first intend to identify the mass ranges of the most efficient dust producing stars at high redshift. We ascertain the dust production efficiency of stars in the mass range 3-40 M⊙ using observed and theoretical dust yields of AGB stars and SNe. Based on these efficiencies we determine the total dust productivity for different stellar sources and investigate its dependency on the initial mass function (IMF). It is found that the dust production efficiency generally decreases with increasing progenitor mass. The total dust production strongly

  1. Carbon isotope excursions in paleosol carbonate marking five early Eocene hyperthermals in the Bighorn Basin, Wyoming

    Directory of Open Access Journals (Sweden)

    H. A. Abels

    2015-05-01

    Full Text Available Transient greenhouse warming events in the Paleocene and Eocene were associated with the addition of isotopically-light carbon to the exogenic atmosphere–ocean carbon pool, leading to substantial environmental and biotic change. The magnitude of an accompanying carbon isotope excursion (CIE can be used to constrain both the sources and amounts of carbon released during an event, as well as to correlate marine and terrestrial records with high precision. The Paleocene Eocene Thermal Maximum (PETM is well documented, but CIE records for the subsequent warming events are still rare especially from the terrestrial realm. Here, we provide new CIE records for two of the smaller hyperthermal events, I1 and I2, in paleosol carbonate, as well as two additional records of ETM2 and H2 in the Bighorn Basin. Stratigraphic comparison of this expanded, high-resolution terrestrial carbon isotope record to the deep-sea benthic foraminifera records from ODP Sites 1262 and 1263, Walvis Ridge, in the southern Atlantic Ocean corroborates that the Bighorn Basin fluvial sediments record global atmospheric change. The stratigraphic thicknesses of the eccentricity-driven hyperthermals in these archives are in line with precession-forcing of the 7 m thick fluvial overbank-avulsion sedimentary cycles. Using the CALMAG bulk oxide mean annual precipitation proxy, we reconstruct similar or slightly wetter than background soil moisture contents during the four younger hyperthermals, in contrast to drying observed during the PETM. Soil carbonate CIEs vary in magnitude proportionally with the marine CIEs for the four smaller early Eocene hyperthermals. This relationship breaks down for the PETM, with the soil carbonate CIE ~ 2–4‰ less than expected if all five linearly relate to marine CIEs. If the PETM CO2 forcing was similar but scaled to the younger hyperthermals, photosynthetic isotope fractionation or soil environmental factors are needed to explain this anomaly. We

  2. Cosmological Consequences of QCD Phase Transition(s) in Early Universe

    CERN Document Server

    Tawfik, A

    2008-01-01

    We discuss the cosmological consequences of QCD phase transition(s) on the early universe. We argue that our recent knowledge about the transport properties of quark-gluon plasma (QGP) should throw additional lights on the actual time evolution of our universe. Understanding the nature of QCD phase transition(s), which can be studied in lattice gauge theory and verified in heavy ion experiments, provides an explanation for cosmological phenomenon stem from early universe.

  3. University Students in the Digital Age: Early Conceptual Approaches

    Directory of Open Access Journals (Sweden)

    Lucía Trotta

    2012-11-01

    Full Text Available This article aims to reconstruct the socialcultural characteristics and profiles of young university students of La Plata University. In particular, it searches for main access and use of new technologies, the ways of getting information, the recreation and sociability frames, in order to wonder about its influences on the political experiences of students.

  4. Particle creation in the early Universe: achievements and problems

    CERN Document Server

    Grib, A A

    2016-01-01

    Results on particle creation from vacuum by the gravitational field of the expanding Friedmann Universe are presented. Finite results for the density of particles and the energy density for created particles are given for different exact solutions for different regimes of the expansion of the Universe. The results are obtained as for conformal as for nonconformal particles. The hypothesis of the origination of visible matter from the decay of created from vacuum superheavy particles identified with the dark matter is discussed.

  5. Quantum Field Theory and Decoherence in the Early Universe

    Science.gov (United States)

    Koksma, J. F.

    2011-06-01

    Quantum field theory is indispensable for understanding many aspects of cosmology, both in the early Universe and today. For example, quantum processes could be paramount to understand the nature of the mysterious dark energy resulting in the Universe’s recently observed accelerated expansion. Inspired by these considerations, this PhD thesis is concerned with two aspects of quantum field theory relevant to cosmology: quantum backreaction and decoherence. Quantum backreaction is a line of research where the impact of quantum fluctuations on the background spacetime geometry in perturbative quantum gravity is investigated. The cosmological constant problem and the process of quantum backreaction are intimately related: quantum backreaction might provide us with a dynamical mechanism to effectively make the cosmological constant almost vanish. We investigate the quantum backreaction of the trace anomaly and of fermions. We find that the trace anomaly does not dynamically influence the effective value of the cosmological constant. We furthermore evaluate the fermion propagator in FLRW spacetimes with constant deceleration. Although the dynamics resulting from the one-loop stress-energy tensor need yet to be investigated, we find that we certainly cannot exclude a significant effect due to the quantum backreaction on the Universe’s expansion. Decoherence is a quantum theory which addresses the quantum-to-classical transition of a particular system. The idea of the decoherence formalism is that a macroscopic system cannot be separated from its environment. The framework of decoherence is widely used, e.g. in quantum computing, black hole physics, inflationary perturbation theory, and in elementary particle physics, such as electroweak baryogenesis models. We formulate a novel “correlator approach” to decoherence: neglecting observationally inaccessible correlators gives rise to an increase in entropy of the system, as perceived by an observer. This is inspired

  6. Weight Percentage of Calcium Carbonate for 17 Equatorial Pacific Cores from Brown University

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Weight percentages of calcium carbonate in this file were compiled by J. Farrell and W. L. Prell of Brown University for 17 equatorial Pacific Ocean sediment cores....

  7. Early Carbonation Behavior of High-volume Dolomite Powder-cement Based Materials

    Institute of Scientific and Technical Information of China (English)

    YANG Huamei; HE zhen; SHAO Yixin

    2015-01-01

    Combined with DTG analysis, X-Ray diffraction analysis (XRD) andfi eld emission scanning electron microscopy analysis (FSEM) affi liated with energy dispersive spectrometer analysis (EDS), the early hydration and carbonation behavior of cement paste compacts incorporated with 30% of dolomite powder at low water to cement ratio (0.15) was investigated. The results showed that early carbonation curing was capable of developing rapid early strength. It is noted that the carbonation duration should be strictly controlled otherwise subsequent hydration might be hindered. Dolomite powder acted as nuclei of crystallization, resulting in acceleration of products formation and refi nement of products crystal size. Therefore, as for cement-based material, it was found that early carbonation could reduce cement dosages to a large extent and promote rapid strength gain resulting from rapid formation of products, supplemental enhancement due to water release in the reaction of carbonation, and formation of nanometer CaCO3 skeleton network at early age.

  8. "Managing" Disability: Early Experiences of University Students with Disabilities

    Science.gov (United States)

    Goode, Jackie

    2007-01-01

    Recent UK legislation, operational from December 2006, places a duty on all public authorities, including higher education institutions, to actively promote equality of opportunity for people with disabilities. The university studied here has a number of initiatives in place to develop good practice in this area, but how do students themselves…

  9. Technology Commercialization as University Mission: Early Historical Developments at the University of Toronto.

    Science.gov (United States)

    Sá, Creso M; Kretz, Andrew

    2016-01-01

    Canadian universities are perceived as less vibrant and engaged generators of technologies with commercial value than their American counterparts, and such perceptions have driven science policy for decades. This paper shows that contrary to these prevailing views, Canada's largest university has a long history of experience in dealing with the technological gaps in national industry and in attempting to work with domestic firms. Three historical periods, particularly critical in shaping these interactions, are identified and discussed. By the time policy initiatives began emphasizing university-industry relationships, the university had already built essential organizational underpinnings for the commercialization of technologies.

  10. Social Strategies during University Studies Predict Early Career Work Burnout and Engagement: 18-Year Longitudinal Study

    Science.gov (United States)

    Salmela-Aro, Katariina; Tolvanen, Asko; Nurmi, Jari-Erik

    2011-01-01

    This longitudinal study spanning 18 years examined the role of social strategies in early career adaptation. The aim was to find out whether individuals' social strategies measured during their university studies had an impact on work burnout and work engagement measured 10-18 years later. A sample of 292 university students completed the SAQ…

  11. Carbonate platform evidence of ocean acidification at the onset of the early Toarcian oceanic anoxic event

    Science.gov (United States)

    Trecalli, Alberto; Spangenberg, Jorge; Adatte, Thierry; Föllmi, Karl B.; Parente, Mariano

    2012-12-01

    The early Toarcian oceanic anoxic event (Early Jurassic;˜183 Myr ago) is associated with one of the largest negative carbon isotope excursion (CIE) in the whole Phanerozoic (3-7‰). Estimates of the magnitude and rate of CO2 injection in the ocean-atmosphere system are compatible with a scenario of ocean acidification. Many carbonate platforms drowned in the Pliensbachian, well before the early Toarcian event. In this paper we test the hypothesis of surface water ocean acidification by presenting data from a resilient carbonate platform: the Apennine Carbonate Platform of southern Italy. The studied sections document a dramatic shift of the carbonate factory from massive biocalcification to chemical precipitation. Lithiotis bivalves and calcareous algae (Palaeodasycladus mediterraneus), which were the most prolific carbonate producers of Pliensbachian carbonate platforms, disappear during the first phase of the early Toarcian CIE, before the most depleted values are reached. We discuss the local versus supraregional significance of this shift and propose a scenario involving abrupt decline of carbonate saturation, forced by CO2 release at the beginning of the early Toarcian CIE, followed by a calcification overshoot, driven by the recovery of ocean alkalinity. Attribution of the demise of carbonate platform hypercalcifiers to ocean acidification is supported by palaeophysiology and reinforced by experimental data on the detrimental effects of ocean acidification on recent shellfishes and calcareous algae.

  12. Viscous Quark-Gluon Plasma in the Early Universe

    CERN Document Server

    Tawfik, A; Mansour, H; Harko, T

    2010-01-01

    We consider the evolution of a flat, isotropic and homogeneous Friedmann-Robertson-Walker Universe, filled with a causal bulk viscous cosmological fluid, that can be characterized by an ultra-relativistic equation of state and bulk viscosity coefficient obtained from recent lattice QCD calculations. The basic equation for the Hubble parameter is derived under the assumption that the total energy in the Universe is conserved. By assuming a power law dependence of bulk viscosity coefficient, temperature and relaxation time on energy density, an approximate solution of the field equations has been obtained, in which we utilized equations of state from recent lattice QCD simulations QCD and heavy-ion collisions to derive an evolution equation. In this treatment for the viscous cosmology, we found no evidence for singularity. For example, both Hubble parameter and scale factor are finite at $t=0$, $t$ is the comoving time. Furthermore, their time evolution essentially differs from the one associated with non-visco...

  13. Nuclear and particle physics in the early universe

    Science.gov (United States)

    Schramm, D. N.

    1981-01-01

    Basic principles and implications of Big Bang cosmology are reviewed, noting the physical evidence of a previous universe temperature of 10,000 K and theoretical arguments such as grand unification decoupling indicating a primal temperature of 10 to the 15th eV. The Planck time of 10 to the -43rd sec after the Big Bang is set as the limit before which gravity was quantized and nothing is known. Gauge theories of elementary particle physics are reviewed for successful predictions of similarity in weak and electromagnetic interactions and quantum chromodynamic predictions for strong interactions. The large number of photons in the universe relative to the baryons is considered and the grand unified theories are cited as showing the existence of baryon nonconservation as an explanation. Further attention is given to quark-hadron phase transition, the decoupling for the weak interaction and relic neutrinos, and Big Bang nucleosynthesis.

  14. Coaching to Quality: Increasing Quality in Early Care and Education Programmes through Community-University Partnership

    Science.gov (United States)

    Gilbert, Jaesook Lee; Harte, Helene Arbouet

    2013-01-01

    This paper describes efforts to increase the quality in early care and education through targeted coaching. A collaborative including several community agencies and a university developed a framework of support for early care and education providers, using coaching as its foundational basis, called Coaching to Quality (CTQ). This paper provides a…

  15. A Case Study of the Development of an Early Retirement Program for University Faculty.

    Science.gov (United States)

    Chronister, Jay L.; Trainer, Aileen

    1985-01-01

    To offset declining enrollments, financial constraints, younger faculties, and high tenure ratios, some institutions are considering early retirement programs to facilitate faculty turnover. A University of Virginia faculty committee reviewed several early retirement options and selected a cost-effective bridging program with ample incentives and…

  16. The Cosmic Microwave Background Radiation-A Unique Window on the Early Universe

    Science.gov (United States)

    Hinshaw, Gary

    2010-01-01

    The cosmic microwave background radiation is the remnant heat from the Big Bang. It provides us with a unique probe of conditions in the early universe, long before any organized structures had yet formed. The anisotropy in the radiation's brightness yields important clues about primordial structure and additionally provides a wealth of information about the physics of the early universe. Within the framework of inflationary dark matter models, observations of the anisotropy on sub-degree angular scales reveals the signatures of acoustic oscillations of the photon-baryon fluid at a redshift of 11 00. Data from the first seven years of operation of the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide detailed full-sky maps of the cosmic microwave background temperature and polarization anisotropy. Together, the data provide a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time. WMAP, part of NASA's Explorers program, was launched on June 30, 2001. The WMAP satellite was produced in a partnership between the Goddard Space Flight Center and Princeton University. The WMAP team also includes researchers at the Johns Hopkins University; the Canadian Institute of Theoretical Astrophysics; University of Texas; Oxford University; University of Chicago; Brown University; University of British Columbia; and University of California, Los Angeles.

  17. The Cosmic Microwave Background Radiation-A Unique Window on the Early Universe

    Science.gov (United States)

    Hinshaw, Gary

    2010-01-01

    The cosmic microwave background radiation is the remnant heat from the Big Bang. It provides us with a unique probe of conditions in the early universe, long before any organized structures had yet formed. The anisotropy in the radiation's brightness yields important clues about primordial structure and additionally provides a wealth of information about the physics of the early universe. Within the framework of inflationary dark matter models, observations of the anisotropy on sub-degree angular scales reveals the signatures of acoustic oscillations of the photon-baryon fluid at a redshift of 11 00. Data from the first seven years of operation of the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide detailed full-sky maps of the cosmic microwave background temperature and polarization anisotropy. Together, the data provide a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time. WMAP, part of NASA's Explorers program, was launched on June 30, 2001. The WMAP satellite was produced in a partnership between the Goddard Space Flight Center and Princeton University. The WMAP team also includes researchers at the Johns Hopkins University; the Canadian Institute of Theoretical Astrophysics; University of Texas; Oxford University; University of Chicago; Brown University; University of British Columbia; and University of California, Los Angeles.

  18. Dusty starburst galaxies in the early Universe as revealed by gravitational lensing

    CERN Document Server

    Vieira, J D; Chapman, S C; De Breuck, C; Hezaveh, Y D; Weiss, A; Aguirre, J E; Aird, K A; Aravena, M; Ashby, M L N; Bayliss, M; Benson, B A; Biggs, A D; Bleem, L E; Bock, J J; Bothwell, M; Bradford, C M; Brodwin, M; Carlstrom, J E; Chang, C L; Crawford, T M; Crites, A T; de Haan, T; Dobbs, M A; Fomalont, E B; Fassnacht, C D; George, E M; Gladders, M D; Gonzalez, A H; Greve, T R; Gullberg, B; Halverson, N W; High, F W; Holder, G P; Holzapfel, W L; Hoover, S; Hrubes, J D; Hunter, T R; Keisler, R; Lee, A T; Leitch, E M; Lueker, M; Luong-Van, D; Malkan, M; McIntyre, V; McMahon, J J; Mehl, J; Menten, K M; Meyer, S S; Mocanu, L M; Murphy, E J; Natoli, T; Padin, S; Plagge, T; Reichardt, C L; Rest, A; Ruel, J; Ruhl, J E; Sharon, K; Schaffer, K K; Shaw, L; Shirokoff, E; Spilker, J S; Stalder, B; Staniszewski1, Z; Stark, A A; Story, K; Vanderlinde, K; Welikala, N; Williamson, R; 10.1038/nature1200

    2013-01-01

    In the past decade, our understanding of galaxy evolution has been revolutionized by the discovery that luminous, dusty, starburst galaxies were 1,000 times more abundant in the early Universe than at present. It has, however, been difficult to measure the complete redshift 2 distribution of these objects, especially at the highest redshifts (z > 4). Here we report a redshift survey at a wavelength of three millimeters, targeting carbon monoxide line emission from the star-forming molecular gas in the direction of extraordinarily bright millimetrewave-selected sources. High-resolution imaging demonstrates that these sources are strongly gravitationally lensed by foreground galaxies. We detect spectral lines in 23 out of 26 sources and multiple lines in 12 of those 23 sources, from which we obtain robust, unambiguous redshifts. At least 10 of the sources are found to lie at z > 4, indicating that the fraction of dusty starburst galaxies at high redshifts is greater than previously thought. Models of lens geome...

  19. Dusty starburst galaxies in the early Universe as revealed by gravitational lensing.

    Science.gov (United States)

    Vieira, J D; Marrone, D P; Chapman, S C; De Breuck, C; Hezaveh, Y D; Weiβ, A; Aguirre, J E; Aird, K A; Aravena, M; Ashby, M L N; Bayliss, M; Benson, B A; Biggs, A D; Bleem, L E; Bock, J J; Bothwell, M; Bradford, C M; Brodwin, M; Carlstrom, J E; Chang, C L; Crawford, T M; Crites, A T; de Haan, T; Dobbs, M A; Fomalont, E B; Fassnacht, C D; George, E M; Gladders, M D; Gonzalez, A H; Greve, T R; Gullberg, B; Halverson, N W; High, F W; Holder, G P; Holzapfel, W L; Hoover, S; Hrubes, J D; Hunter, T R; Keisler, R; Lee, A T; Leitch, E M; Lueker, M; Luong-Van, D; Malkan, M; McIntyre, V; McMahon, J J; Mehl, J; Menten, K M; Meyer, S S; Mocanu, L M; Murphy, E J; Natoli, T; Padin, S; Plagge, T; Reichardt, C L; Rest, A; Ruel, J; Ruhl, J E; Sharon, K; Schaffer, K K; Shaw, L; Shirokoff, E; Spilker, J S; Stalder, B; Staniszewski, Z; Stark, A A; Story, K; Vanderlinde, K; Welikala, N; Williamson, R

    2013-03-21

    In the past decade, our understanding of galaxy evolution has been revolutionized by the discovery that luminous, dusty starburst galaxies were 1,000 times more abundant in the early Universe than at present. It has, however, been difficult to measure the complete redshift distribution of these objects, especially at the highest redshifts (z > 4). Here we report a redshift survey at a wavelength of three millimetres, targeting carbon monoxide line emission from the star-forming molecular gas in the direction of extraordinarily bright millimetre-wave-selected sources. High-resolution imaging demonstrates that these sources are strongly gravitationally lensed by foreground galaxies. We detect spectral lines in 23 out of 26 sources and multiple lines in 12 of those 23 sources, from which we obtain robust, unambiguous redshifts. At least 10 of the sources are found to lie at z > 4, indicating that the fraction of dusty starburst galaxies at high redshifts is greater than previously thought. Models of lens geometries in the sample indicate that the background objects are ultra-luminous infrared galaxies, powered by extreme bursts of star formation.

  20. Connecting early and late universe by $f(R)$ gravity

    CERN Document Server

    Capozziello, Salvatore; Luongo, Orlando

    2014-01-01

    Inflation and dark energy are two of the most relevant aspects of modern cosmology. These different epochs provide the universe is passing through accelerated phases soon after the Big-Bang and at present stage of its evolution. In this review paper, we discuss that both eras can be, in principle, described by a geometric picture, under the standard of $f(R)$ gravity. We give the fundamental physics motivations and outline the main ingredients of $f(R)$ inflation, quintessence and cosmography. This wants to be a quick summary of $f(R)$ paradigm without claiming of completeness.

  1. Connecting early and late universe by f(R) gravity

    Science.gov (United States)

    Capozziello, Salvatore; de Laurentis, Mariafelicia; Luongo, Orlando

    2015-12-01

    Inflation and dark energy are two of the most relevant aspects of modern cosmology. These different epochs provide the universe is passing through accelerated phases soon after the Big-Bang and at present stage of its evolution. In this review paper, we discuss that both eras can be, in principle, described by a geometric picture, under the standard of f(R) gravity. We give the fundamental physics motivations and outline the main ingredients of f(R) inflation, quintessence and cosmography. This wants to be a quick summary of f(R) paradigm without claiming of completeness.

  2. Searches for Cold Relics of the Early Universe

    Science.gov (United States)

    Baudis, Laura

    2005-11-01

    Up to 90% of matter in the Universe could be composed of heavy particles, which were non-relativistic, or 'cold', when they froze-out from the primordial soup. I will review current searches for these hypothetical particles, both via elastic scattering from nuclei in deep underground detectors, and via the observation of their annihilation products in the Sun, galactic halo and galactic center. The emphasis will be on most recent results, and on comparison with reaches of future particle colliders, such as the LHC and ILC.

  3. The quark gluon plasma equation of state and the expansion of the early Universe

    Energy Technology Data Exchange (ETDEWEB)

    Sanches, S.M.; Navarra, F.S.; Fogaça, D.A., E-mail: david@if.usp.br

    2015-05-15

    Our knowledge of the equation of state of the quark gluon plasma has been continuously growing due to the experimental results from heavy ion collisions, due to recent astrophysical measurements and also due to the advances in lattice QCD calculations. The new findings about this state may have consequences on the time evolution of the early Universe, which can be estimated by solving the Friedmann equations. The solutions of these equations give the time evolution of the energy density and also of the temperature in the beginning of the Universe. In this work we compute the time evolution of the QGP in the early Universe, comparing several equations of state, some of them based on the MIT bag model (and on its variants) and some of them based on lattice QCD calculations. Among other things, we investigate the effects of a finite baryon chemical potential in the evolution of the early Universe.

  4. INITIAL STAGES OF CARBON GENESIS IN THE UNIVERSE

    Directory of Open Access Journals (Sweden)

    A.L. Vereshchagin

    2004-12-01

    Full Text Available The formation possibility of the most widespread carbon compounds had been showed on the base of detonation nanodiamonds thermodynamic data. These reactions may play a key role in the life origin and in the atmosphere formation of the Solar system giant planets

  5. Viscous quark-gluon plasma in the early universe

    Energy Technology Data Exchange (ETDEWEB)

    Tawfik, A.; Wahba, M. [Egyptian Center for Theoretical Physics (ECTP), MTI University, Al-Mukkatam, Cairo 11212 (Egypt); Mansour, H. [Department of Physics, Cairo University, Giza 12613 (Egypt); Harko, T. [Department of Physics and Center for Theoretical and Computational Physics, The University of Hong Kong, Pok Fu Lam Road (China)

    2011-03-15

    In the present work a study is given for the evolution of a flat, isotropic and homogeneous Universe, which is filled with a causal bulk viscous cosmological fluid. We describe the viscous properties by an ultra-relativistic equation of state, and bulk viscosity coefficient obtained from recent lattice QCD calculations. The basic equation for the Hubble parameter is derived by using the energy equation obtained from the assumption of the covariant conservation of the energy-momentum tensor of the matter in the Universe. By assuming a power law dependence of the bulk viscosity coefficient, temperature and relaxation time on the energy density, we derive the evolution equation for the Hubble function. By using the equations of state from recent lattice QCD simulations and heavy-ion collisions we obtain an approximate solution of the field equations. In this treatment for the viscous cosmology, no evidence for singularity is observed. For example, both the Hubble parameter and the scale factor are finite at t=0, where t is the comoving time. Furthermore, their time evolution essentially differs from the one associated with non-viscous and ideal gas. Also it is noticed that the thermodynamic quantities, like temperature, energy density and bulk pressure remain finite. Particular solutions are also considered in order to prove that the free parameter in this model does qualitatively influence the final results. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Statistical mechanics and the description of the early universe I

    DEFF Research Database (Denmark)

    Pessah, Martin Elias; F. Torres, Diego; Vucetich, H.

    2001-01-01

    We analyze how the thermal history of the universe is influenced by the statistical description, assuming a deviation from the usual Bose-Einstein, Fermi-Dirac and Boltzmann-Gibbs distribution functions. These deviations represent the possible appearance of non-extensive effects related with the ......We analyze how the thermal history of the universe is influenced by the statistical description, assuming a deviation from the usual Bose-Einstein, Fermi-Dirac and Boltzmann-Gibbs distribution functions. These deviations represent the possible appearance of non-extensive effects related...... law, and provide an estimate on how known cosmological bounds on the masses of neutrinos are modified by a change in the statistics. We particularly analyze here the recombination epoch, making explicit use of the chemical potentials involved in order to attain the necessary corrections. All...... these results constitute the basic tools needed for placing bounds on the amount of non-extensivity that could be present at different eras and will be later used to study primordial nucleosynthesis....

  7. Segue 1: An unevolved fossil galaxy from the early universe

    Energy Technology Data Exchange (ETDEWEB)

    Frebel, Anna [Kavli Institute for Astrophysics and Space Research and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Simon, Joshua D. [Observatories of the Carnegie Institution of Washington, Pasadena, CA 91101 (United States); Kirby, Evan N. [Center for Galaxy Evolution, Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States)

    2014-05-01

    We present Magellan/MIKE and Keck/HIRES high-resolution spectra of six red giant stars in the dwarf galaxy Segue 1. Including one additional Segue 1 star observed by Norris et al., high-resolution spectra have now been obtained for every red giant in Segue 1. Remarkably, three of these seven stars have metallicities below [Fe/H] = –3.5, suggesting that Segue 1 is the least chemically evolved galaxy known. We confirm previous medium-resolution analyses demonstrating that Segue 1 stars span a metallicity range of more than 2 dex, from [Fe/H] = –1.4 to [Fe/H] = –3.8. All of the Segue 1 stars are α-enhanced, with [α/Fe] ∼ 0.5. High α-element abundances are typical for metal-poor stars, but in every previously studied galaxy [α/Fe] declines for more metal-rich stars, which is typically interpreted as iron enrichment from supernova Ia. The absence of this signature in Segue 1 indicates that it was enriched exclusively by massive stars. Other light element abundance ratios in Segue 1, including carbon enhancement in the three most metal-poor stars, closely resemble those of metal-poor halo stars. Finally, we classify the most metal-rich star as a CH star given its large overabundances of carbon and s-process elements. The other six stars show remarkably low neutron-capture element abundances of [Sr/H] < –4.9 and [Ba/H] < –4.2, which are comparable to the lowest levels ever detected in halo stars. This suggests minimal neutron-capture enrichment, perhaps limited to a single r-process or weak s-process synthesizing event. Altogether, the chemical abundances of Segue 1 indicate no substantial chemical evolution, supporting the idea that it may be a surviving first galaxy that experienced only one burst of star formation.

  8. Opening A New Window to the Early Universe

    CERN Document Server

    Hivon, E; Hivon, Eric; Kamionkowski, Marc

    2002-01-01

    DASI has ended a 34-year quest to detect the CMB polarization, sounding the starting gun for a new race to peer further back in time, with more precision than ever before. Many more CMB polarization experiments are in progress or planned. NASA's recently launched Microwave Anisotropy Probe (MAP) should detect the large-angle polarization induced by early star formation. This should be followed by increasingly precise ground and balloon experiments leading to the Launch of the European Space Agency's Planck satellite in 2007. If the recent past is any indication, studies of the CMB will continue to advance cosmology, even after Planck.

  9. Carbon dioxide fluxes from Tifway bermudagrass: early results

    Science.gov (United States)

    Cotten, David L.; Zhang, G.; Leclerc, M. Y.; Raymer, P.; Steketee, C. J.

    2016-06-01

    This paper reports for the first time preliminary data on carbon uptake of warm-season turfgrass at a well-managed sod farm in south central Georgia. It examines the changes in carbon uptake from one of the most widely used warm-season turfgrass cultivars in the world, Tifway Bermudagrass. It elucidates the role of canopy density and light avalaibility on the net carbon uptake using the eddy-covariance technique. Preliminary evidence suggests that turfgrass is effective at sequestering carbon dioxide during the summer months even when the canopy is being reestablished following a grass harvest.

  10. High-Redshift galaxies light from the early universe

    CERN Document Server

    Appenzeller, Immo

    2008-01-01

    This book provides a comprehensive account of the scientific results on high-redshift galaxies accumulated during the past ten years. Apart from summarizing and critically discussing the wealth of observational data, the observational methods which made it possible to study these very distant and extremely faint objects are described in detail. Moreover, the technical feasibilities and physical limitations for existing and for future ground-based and space-based telescopes are discussed. Thus, apart from summarizing the knowledge accumulated so far, the book is designed as a tool for planning future observational and instrumental programs and projects. In view of the potential importance of the observational results of the high-redshift universe for basic physics the book is written for astronomers as well as for physicists without prior astronomical knowledge. For this purpose it contains introductory chapters describing the basic concepts and notations used in modern astronomy and a brief overview of the pr...

  11. Strongly broken Peccei-Quinn symmetry in the early Universe

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Fuminobu [Department of Physics, Tohoku University,Sendai, Miyagi 980-8578 (Japan); Kavli IPMU (WPI), TODIAS, The University of Tokyo,Kashiwa, Chiba 277-8583 (Japan); Yamada, Masaki [Kavli IPMU (WPI), TODIAS, The University of Tokyo,Kashiwa, Chiba 277-8583 (Japan); Institute for Cosmic Ray Research, ICRR, The University of Tokyo,Kashiwa, Chiba 277-8582 (Japan)

    2015-10-06

    We consider QCD axion models where the Peccei-Quinn symmetry is badly broken by a larger amount in the past than in the present, in order to avoid the axion isocurvature problem. Specifically we study supersymmetric axion models where the Peccei-Quinn symmetry is dynamically broken by either hidden gauge interactions or the SU(3){sub c} strong interactions whose dynamical scales are temporarily enhanced by the dynamics of flat directions. The former scenario predicts a large amount of self-interacting dark radiation as the hidden gauge symmetry is weakly coupled in the present Universe. We also show that the observed amount of baryon asymmetry can be generated by the QCD axion dynamics via spontaneous baryogenesis. We briefly comment on the case in which the PQ symmetry is broken by a non-minimal coupling to gravity.

  12. Cyclic models of the relativistic universe: the early history

    CERN Document Server

    Kragh, Helge

    2013-01-01

    Within the framework of relativistic cosmology oscillating or cyclic models of the universe were introduced by A. Friedmann in his seminal paper of 1922. With the recognition of evolutionary cosmology in the 1930s this class of closed models attracted considerable interest and was investigated by several physicists and astronomers. Whereas the Friedmann-Einstein model exhibited only a single maximum value, R. Tolman argued for an endless series of cycles. After World War II, cyclic or pulsating models were suggested by W. Bonnor and H. Zanstra, among others, but they remained peripheral to mainstream cosmology. The paper reviews the development from 1922 to the 1960s, paying particular attention to the works of Friedmann, Einstein, Tolman and Zanstra. It also points out the role played by bouncing models in the emergence of modern big-bang cosmology.

  13. The art and science of prognostication in early university medicine.

    Science.gov (United States)

    Demaitre, Luke

    2003-01-01

    Prognosis occupied a more prominent place in the medieval curriculum than it does at the modern university. Scholastic discussions were rooted in the Hippocratic Aphorisms and shaped by Galen's treatises On Crisis and On Critical Days. Medical prediction, as an art dependent on personal skills such as memory and conjecture, was taught with the aid of the liberal arts of rhetoric and logic. Scientific predictability was sought in branches of mathematics, moving from periodicity and numerology to astronomy. The search for certitude contributed to the cultivation of astrology; even at its peak, however, astrological medicine did not dominate the teaching on prognostication. The ultimate concern, which awaits further discussion, was not even with forecasting as such, but with the physician and, indeed, the patient.

  14. Constraining resonant photon-axion conversions in the Early Universe

    Energy Technology Data Exchange (ETDEWEB)

    Mirizzi, Alessandro [Max-Planck-Inst. fuer Physik (Werner-Heisenberg-Inst.), Muenchen (Germany); Redondo, Javier [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Sigl, Guenter [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik

    2009-05-15

    The presence of a primordial magnetic field would have induced resonant conversions between photons and axion-like particles (ALPs) during the thermal history of the Universe. These conversions would have distorted the blackbody spectrum of the cosmic microwave background (CMB). In this context, we derive bounds on the photon-ALP resonant conversions using the high precision CMB spectral data collected by the FIRAS instrument on board of the Cosmic Background Explorer. We obtain upper limits on the product of the photon-ALP coupling constant g times the magnetic field strength B down to gB

  15. Constraining resonant photon-axion conversions in the early universe

    Science.gov (United States)

    Mirizzi, Alessandro; Redondo, Javier; Sigl, Günter

    2009-08-01

    The presence of a primordial magnetic field would have induced resonant conversions between photons and axion-like particles (ALPs) during the thermal history of the Universe. These conversions would have distorted the blackbody spectrum of the cosmic microwave background (CMB). In this context, we derive bounds on the photon-ALP resonant conversions using the high precision CMB spectral data collected by the FIRAS instrument on board of the Cosmic Background Explorer. We obtain upper limits on the product of the photon-ALP coupling constant g times the magnetic field strength B down to gB lesssim 10-13 GeV-1 nG for ALP masses below the eV scale.

  16. Constraining resonant photon-axion conversions in the Early Universe

    CERN Document Server

    Mirizzi, Alessandro; Sigl, Guenter

    2009-01-01

    The presence of a primordial magnetic field would have induced resonant conversions between photons and axion-like particles (ALPs) during the thermal history of the Universe. These conversions would have distorted the blackbody spectrum of the cosmic microwave background (CMB). In this context, we derive bounds on the photon-ALP resonant conversions using the high precision CMB spectral data collected by the FIRAS instrument on board of the Cosmic Background Explorer. We obtain upper limits on the product of the photon-ALP coupling constant g times the magnetic field strength B down to g B > 10^{-13} GeV^{-1} nG for ALP masses below the eV scale.

  17. Underground Searches for Cold Relics of the Early Universe

    CERN Document Server

    Baudis, L

    2005-01-01

    We have strong evidence on all cosmic scales, from galaxies to the largest structures ever observed, that there is more matter in the universe than we can see. Galaxies and clusters would fly apart unless they would be held together by material which we call dark, because it does not shine in photons. Although the amount of dark matter and its distribution are fairly well established, we are clueless regarding its composition. Leading candidates are Weakly Interacting Massive Particles (WIMPs), which are 'cold' thermal relics of the Big Bang, ie moving non-relativistically at the time of structure formation. These particles can be detected via their interaction with nuclei in deep-underground, low-background detectors. Experiments dedicated to observe WIMP interactions for the first time reach sensitivities allowing to probe the parameter space predicted by supersymmetric theories of particle physics. Current results of high sensitivity direct detection experiments are discussed and the most promising project...

  18. Selections from 2016: Faintest Early-Universe Galaxy Found

    Science.gov (United States)

    Kohler, Susanna

    2016-12-01

    Editors note:In these last two weeks of 2016, well be looking at a few selections that we havent yet discussed on AAS Nova from among the most-downloaded paperspublished in AAS journals this year. The usual posting schedule will resume after the AAS winter meeting.Detection of Lyman-Alpha Emission from a Triply Imaged z = 6.85 Galaxy Behind MACS J2129.40741Published May2016Main takeaway:A team led by Kuang-Han Huang (University of Caliornia, Davis) discovered a faint galaxy at z = 6.846 located behind the galaxy cluster MACS J2129.40741. This galaxy contains only one ten-thousandth the stellar mass of the Milky Way, and its the faintest galaxy weve found at this great distance.Why its interesting:This galaxy is roughly 13 billion years old, placing it near the end of the reionization epoch (in which the first stars formed and caused our universe to transition from neutral gas to ionized gas). Examining such a small galaxy at this distance provides valuable information about how the process of reionization may have occurred.About the discovery:The newly discovered galaxy was found due to a fortunate alignment with a foreground galaxy cluster. Gravitational lensing by the foreground cluster produced three images of the distant galaxy, which were identified as being the same galaxy due to their similar spectra.CitationKuang-Han Huang et al 2016 ApJL 823 L14. doi:10.3847/2041-8205/823/1/L14

  19. Organic carbon isotopes of the Sinian and Early Cambrian black shales on Yangtze Platform, China

    Institute of Scientific and Technical Information of China (English)

    李任伟; 卢家烂; 张淑坤; 雷加锦

    1999-01-01

    Organic matter of the Sinian and early Cambrian black shales on the Yangtze Platform belongs to the light carbon group of isotopes with the δ13C values from - 27 % to -35 % , which are lower than those of the contemporaneously deposited carbonates and phosphorites. A carbon isotope-stratified paleooceanographic model caused by upwelling is proposed, which can be used not only to interpret the characteristics of organic carbon isotopic compositions of the black shales, but also to interpret the paleogeographic difference in the organic carbon isotope compositions of various types of sedimentary rocks.

  20. A massive, dead disk galaxy in the early Universe.

    Science.gov (United States)

    Toft, Sune; Zabl, Johannes; Richard, Johan; Gallazzi, Anna; Zibetti, Stefano; Prescott, Moire; Grillo, Claudio; Man, Allison W S; Lee, Nicholas Y; Gómez-Guijarro, Carlos; Stockmann, Mikkel; Magdis, Georgios; Steinhardt, Charles L

    2017-06-21

    At redshift z = 2, when the Universe was just three billion years old, half of the most massive galaxies were extremely compact and had already exhausted their fuel for star formation. It is believed that they were formed in intense nuclear starbursts and that they ultimately grew into the most massive local elliptical galaxies seen today, through mergers with minor companions, but validating this picture requires higher-resolution observations of their centres than is currently possible. Magnification from gravitational lensing offers an opportunity to resolve the inner regions of galaxies. Here we report an analysis of the stellar populations and kinematics of a lensed z = 2.1478 compact galaxy, which-surprisingly-turns out to be a fast-spinning, rotationally supported disk galaxy. Its stars must have formed in a disk, rather than in a merger-driven nuclear starburst. The galaxy was probably fed by streams of cold gas, which were able to penetrate the hot halo gas until they were cut off by shock heating from the dark matter halo. This result confirms previous indirect indications that the first galaxies to cease star formation must have gone through major changes not just in their structure, but also in their kinematics, to evolve into present-day elliptical galaxies.

  1. Holographic Inflation and the Low Entropy of the Early Universe

    CERN Document Server

    Banks, Tom

    2015-01-01

    This is a completely rewritten version of the talk I gave at the Philosophy of Cosmology conference in Tenerife, September 2014, which incorporates elements of my IFT Madrid Anthropics Conference talk. The original was too technical. The current version uses intuitive notions from black hole physics to explain the model of inflationary cosmology based on the Holographic Space Time formalism. The reason that the initial state of the universe had low entropy is that more generic states have no localized excitations, since in HST, localized excitations are defined by constraints on the fundamental variables. The only way to obtain a radiation dominated era, is for each time-like geodesic to see an almost uniform gas of small black holes as its horizon expands, such that the holes evaporate into radiation before they collide and coalesce. Comparing the time slicing that follows causal diamonds along a trajectory, with the global FRW slicing, one sees that systems outside the horizon had to undergo inflation, with...

  2. Reconstruction of the early Universe as a convex optimization problem

    Science.gov (United States)

    Brenier, Y.; Frisch, U.; Hénon, M.; Loeper, G.; Matarrese, S.; Mohayaee, R.; Sobolevskiĭ, A.

    2003-12-01

    We show that the deterministic past history of the Universe can be uniquely reconstructed from knowledge of the present mass density field, the latter being inferred from the three-dimensional distribution of luminous matter, assumed to be tracing the distribution of dark matter up to a known bias. Reconstruction ceases to be unique below those scales - a few Mpc - where multistreaming becomes significant. Above 6 h-1 Mpc we propose and implement an effective Monge-Ampère-Kantorovich method of unique reconstruction. At such scales the Zel'dovich approximation is well satisfied and reconstruction becomes an instance of optimal mass transportation, a problem which goes back to Monge. After discretization into N point masses one obtains an assignment problem that can be handled by effective algorithms with not more than O(N3) time complexity and reasonable CPU time requirements. Testing against N-body cosmological simulations gives over 60 per cent of exactly reconstructed points. We apply several interrelated tools from optimization theory that were not used in cosmological reconstruction before, such as the Monge-Ampère equation, its relation to the mass transportation problem, the Kantorovich duality and the auction algorithm for optimal assignment. A self-contained discussion of relevant notions and techniques is provided.

  3. Reconstruction of the early Universe as a convex optimization problem

    CERN Document Server

    Brenier, Y; Hénon, M; Loeper, G; Matarrese, S; Mohayaee, R; Sobolevskii, A

    2003-01-01

    We show that the deterministic past history of the Universe can be uniquely reconstructed from the knowledge of the present mass density field, the latter being inferred from the 3D distribution of luminous matter, assumed to be tracing the distribution of dark matter up to a known bias. Reconstruction ceases to be unique below those scales -- a few Mpc -- where multi-streaming becomes significant. Above 6 Mpc/h we propose and implement an effective Monge-Ampere-Kantorovich method of unique reconstruction. At such scales the Zel'dovich approximation is well satisfied and reconstruction becomes an instance of optimal mass transportation, a problem which goes back to Monge (1781). After discretization into N point masses one obtains an assignment problem that can be handled by effective algorithms with not more than cubic time complexity in N and reasonable CPU time requirements. Testing against N-body cosmological simulations gives over 60% of exactly reconstructed points. We apply several interrelated tools f...

  4. Sugars as the optimal biosynthetic carbon substrate of aqueous life throughout the universe

    Science.gov (United States)

    Weber, A. L.

    2000-01-01

    Our previous analysis of the energetics of metabolism showed that both the biosynthesis of amino acids and lipids from sugars, and the fermentation of organic substrates, were energetically driven by electron transfer reactions resulting in carbon redox disproportionation (Weber, 1997). Redox disproportionation--the spontaneous (energetically favorable) direction of carbon group transformation in biosynthesis--is brought about and driven by the energetically downhill transfer of electron pairs from more oxidized carbon groups (with lower half-cell reduction potentials) to more reduced carbon groups (with higher half-cell reduction potentials). In this report, we compare the redox and kinetic properties of carbon groups in order to evaluate the relative biosynthetic capability of organic substrates, and to identify the optimal biosubstrate. This analysis revealed that sugars (monocarbonyl alditols) are the optimal biosynthetic substrate because they contain the maximum number of biosynthetically useful high energy electrons/carbon atom while still containing a single carbonyl group needed to kinetically facilitate their conversion to useful biosynthetic intermediates. This conclusion applies to aqueous life throughout the Universe because it is based on invariant aqueous carbon chemistry--primarily, the universal reduction potentials of carbon groups.

  5. Stability of extra dimensions in the inflating early universe

    Energy Technology Data Exchange (ETDEWEB)

    Wieck, Clemens

    2015-08-15

    Cosmic inflation is an attractive paradigm to explain the initial conditions of the universe. It can be conveniently described by the dynamics of a single scalar field within N=1 supergravity. Due to the high energy scale during the inflationary epoch, which is favored by recent observations of the cosmic microwave background radiation, and the flatness of the inflaton potential it is necessary to consider inflation in the context of a UV-complete theory like string theory. To this end, we study the effects of moduli stabilization on inflation models in supergravity, focussing on Kahler moduli in type IIB string theory which govern the size of extra dimensions. For generic models of F-term inflation we calculate back-reaction terms by integrating out the moduli at a high energy scale. When the moduli are stabilized supersymmetrically, all effects decouple in the limit of very heavy moduli. The corrections, however, may be sizeable for realistic moduli masses above the Hubble scale and affect the predicted observables of many models like chaotic inflation and hybrid inflation. If, on the other hand, moduli stabilization entails spontaneous supersymmetry breaking, there are non-decoupling effects like soft mass terms for the inflaton. By the example of chaotic inflation we show that a careful choice of parameters and initial conditions is necessary to reconcile large-field inflation with popular moduli stabilization schemes like KKLT stabilization or the Large Volume Scenario. Furthermore, we study the interplay of moduli stabilization and D-term inflation. If inflation is driven by a constant Fayet-Iliopoulos term, the back-reaction decouples but the gravitino mass in the vacuum is surprisingly constrained. For a field-dependent Fayet-Iliopoulos term associated with an anomalous U(1) symmetry we discuss a number of obstructions to realizing inflation. Moreover, we propose a way to evade them using a new mechanism for supersymmetric moduli stabilization with world

  6. Early universe cosmology. In supersymmetric extensions of the standard model

    Energy Technology Data Exchange (ETDEWEB)

    Baumann, Jochen Peter

    2012-03-19

    In this thesis we investigate possible connections between cosmological inflation and leptogenesis on the one side and particle physics on the other side. We work in supersymmetric extensions of the Standard Model. A key role is played by the right-handed sneutrino, the superpartner of the right-handed neutrino involved in the type I seesaw mechanism. We study a combined model of inflation and non-thermal leptogenesis that is a simple extension of the Minimal Supersymmetric Standard Model (MSSM) with conserved R-parity, where we add three right-handed neutrino super fields. The inflaton direction is given by the imaginary components of the corresponding scalar component fields, which are protected from the supergravity (SUGRA) {eta}-problem by a shift symmetry in the Kaehler potential. We discuss the model first in a globally supersymmetric (SUSY) and then in a supergravity context and compute the inflationary predictions of the model. We also study reheating and non-thermal leptogenesis in this model. A numerical simulation shows that shortly after the waterfall phase transition that ends inflation, the universe is dominated by right-handed sneutrinos and their out-of-equilibrium decay can produce the desired matter-antimatter asymmetry. Using a simplified time-averaged description, we derive analytical expressions for the model predictions. Combining the results from inflation and leptogenesis allows us to constrain the allowed parameter space from two different directions, with implications for low energy neutrino physics. As a second thread of investigation, we discuss a generalisation of the inflationary model discussed above to include gauge non-singlet fields as inflatons. This is motivated by the fact that in left-right symmetric, supersymmetric Grand Unified Theories (SUSY GUTs), like SUSY Pati-Salam unification or SUSY SO(10) GUTs, the righthanded (s)neutrino is an indispensable ingredient and does not have to be put in by hand as in the MSSM. We discuss

  7. Early Triassic fluctuations of the global carbon cycle: New evidence from paired carbon isotopes in the western USA basin

    Science.gov (United States)

    Caravaca, Gwénaël; Thomazo, Christophe; Vennin, Emmanuelle; Olivier, Nicolas; Cocquerez, Théophile; Escarguel, Gilles; Fara, Emmanuel; Jenks, James F.; Bylund, Kevin G.; Stephen, Daniel A.; Brayard, Arnaud

    2017-07-01

    In the aftermath of the catastrophic end-Permian mass extinction, the Early Triassic records recurrent perturbations in the carbon isotope signal, most notably during the Smithian and through the Smithian/Spathian Boundary (SSB; 1.5 myr after the Permian/Triassic boundary), which show some of the largest excursions of the Phanerozoic. The late Smithian also corresponds to major biotic turnovers and environmental changes, such as temperature fluctuations, that deeply impacted the recovery after the end-Permian mass extinction. Here we document the paired carbon isotope signal along with an analysis of the trace and major elements at the long-known Hot Springs section (southeastern Idaho, USA). This section records Early Triassic sediments from the Griesbachian-Dienerian up to the lower Spathian. We show that the organic and carbonate δ13C variations mirror the signals identified at a global scale. Particularly, the middle Smithian-SSB event represented by a negative-positive isotopic couplet is well identified and is not of diagenetic origin. We also document a positive excursion potentially corresponding to the Dienerian/Smithian Boundary. Observed Smithian-Spathian excursions are recorded similarly in both the organic and carbonate reservoirs, but the organic matter signal systematically shows unexpectedly dampened variations compared to its carbonate counterpart. Additionally, we show that variations in the net isotopic effect (i.e., Δ13C) probably resulted from a complex set of forcing parameters including either a mixing between terrestrial and marine organic matter depending on the evolution of the depositional setting, or variations in the biological fractionation. We establish that the Δ13C signal cannot be directly related to CO2-driven temperature variations at Hot Springs. Even though the carbon isotope signal mirrors the Early Triassic variations known at the global scale, the Hot Springs signal probably also reflects local influences on the carbon

  8. Soybean Photosynthetic Rate and Carbon Fixation at Early and Late Planting Dates

    Science.gov (United States)

    Early planting (late April to early May) is recommended for increasing soybean yield but a full understanding of the physiological response is lacking. This study was conducted to determine whether carbon dioxide exchange rate (CER) could explain this yield difference. A study with five (2007) and s...

  9. Time variation of the fine structure constant in the early universe and the Bekenstein model

    CERN Document Server

    Mosquera, Mercedes E; Landau, Susana J; Vucetich, Hector

    2007-01-01

    We use observational primordial abundances of $\\De$, $\\Het$, $\\He$ and $\\Li$, recent data from the Cosmic Microwave Background and the 2dFGRS power spectrum, to put limits on the variation of the fine structure constant in the early universe. Furthermore, we use these constraints together with other astronomical and geophysical bounds from the late universe to test Bekenstein's model for the variation of $\\alpha$. The model is not able to fit all observational and experimental data.

  10. The Influence of the Shear on the Gravitational Waves in the Early Anisotropic Universe

    CERN Document Server

    Song, Yoogeun

    2016-01-01

    We study the singularity of the congruences for both timelike and null geodesic curves using the expansion of the early anisotropic Bianchi type I Universe. In this paper, we concentrate on the influence of the shear of the timelike and null geodesic congruences in the early Universe. Under some natural conditions, we derive the Raychaudhuri type equation for the expansion and the shear-related equations. Recently, scientists working on the LIGO (Laser Interferometer Gravitational-Wave Observatory) have shown many possibilities to observing the anisotropy of the primordial gravitational wave background radiation. We deduce the evolution equation for the shear that may be responsible for those observational results.

  11. Climatic consequences of very high carbon dioxide levels in the earth's early atmosphere

    Science.gov (United States)

    Kasting, James F.; Ackerman, Thomas P.

    1986-01-01

    The possible consequences of very high carbon dioxide concentrations in the earth's early atmosphere have been investigated with a radiative-convective climate model. The early atmosphere would apparently have been stable against the onset of a runaway greenhouse (that is, the complete evaporation of the oceans) for carbon dioxide pressures up to at least 100 bars. A 10- to 20-bar carbon dioxide atmosphere, such as may have existed during the first several hundred million years of the earth's history, would have had a surface temperature of approximately 85 to 110 C. The early stratosphere should have been dry, thereby precluding the possibility of an oxygenic prebiotic atmosphere caused by photodissociation of water vapor followed by escape of hydrogen to space. Earth's present atmosphere also appears to be stable against a carbon dioxide-induced runaway greenhouse.

  12. Climatic consequences of very high carbon dioxide levels in the earth's early atmosphere

    Science.gov (United States)

    Kasting, James F.; Ackerman, Thomas P.

    1986-01-01

    The possible consequences of very high carbon dioxide concentrations in the earth's early atmosphere have been investigated with a radiative-convective climate model. The early atmosphere would apparently have been stable against the onset of a runaway greenhouse (that is, the complete evaporation of the oceans) for carbon dioxide pressures up to at least 100 bars. A 10- to 20-bar carbon dioxide atmosphere, such as may have existed during the first several hundred million years of the earth's history, would have had a surface temperature of approximately 85 to 110 C. The early stratosphere should have been dry, thereby precluding the possibility of an oxygenic prebiotic atmosphere caused by photodissociation of water vapor followed by escape of hydrogen to space. Earth's present atmosphere also appears to be stable against a carbon dioxide-induced runaway greenhouse.

  13. Amyloid-carbon hybrid membranes for universal water purification

    Science.gov (United States)

    Bolisetty, Sreenath; Mezzenga, Raffaele

    2016-04-01

    Industrial development, energy production and mining have led to dramatically increased levels of environmental pollutants such as heavy metal ions, metal cyanides and nuclear waste. Current technologies for purifying contaminated waters are typically expensive and ion specific, and there is therefore a significant need for new approaches. Here, we report inexpensive hybrid membranes made from protein amyloid fibrils and activated porous carbon that can be used to remove heavy metal ions and radioactive waste from water. During filtration, the concentration of heavy metal ions drops by three to five orders of magnitude per passage and the process can be repeated numerous times. Notably, their efficiency remains unaltered when filtering several ions simultaneously. The performance of the membrane is enabled by the ability of the amyloids to selectively absorb heavy metal pollutants from solutions. We also show that our membranes can be used to recycle valuable heavy metal contaminants by thermally reducing ions trapped in saturated membranes, leading to the creation of elemental metal nanoparticles and films.

  14. Amyloid-carbon hybrid membranes for universal water purification.

    Science.gov (United States)

    Bolisetty, Sreenath; Mezzenga, Raffaele

    2016-04-01

    Industrial development, energy production and mining have led to dramatically increased levels of environmental pollutants such as heavy metal ions, metal cyanides and nuclear waste. Current technologies for purifying contaminated waters are typically expensive and ion specific, and there is therefore a significant need for new approaches. Here, we report inexpensive hybrid membranes made from protein amyloid fibrils and activated porous carbon that can be used to remove heavy metal ions and radioactive waste from water. During filtration, the concentration of heavy metal ions drops by three to five orders of magnitude per passage and the process can be repeated numerous times. Notably, their efficiency remains unaltered when filtering several ions simultaneously. The performance of the membrane is enabled by the ability of the amyloids to selectively absorb heavy metal pollutants from solutions. We also show that our membranes can be used to recycle valuable heavy metal contaminants by thermally reducing ions trapped in saturated membranes, leading to the creation of elemental metal nanoparticles and films.

  15. Preparedness to Teach: Experiences of the University of Ibadan Early Career Academics

    Science.gov (United States)

    Udegbe, I. Bola

    2016-01-01

    This research examined the experiences of early career academics (ECAs) in terms of their preparedness to teach. Using a survey design involving 104 ECAs in a large Nigeria university, quantitative and qualitative data were obtained to address the research questions raised. Findings showed that (1) prior experience and training impacted on…

  16. The Reluctant Academic: Early-Career Academics in a Teaching-Orientated University

    Science.gov (United States)

    Gale, Helen

    2011-01-01

    This paper is based on research into academic identities amongst early-career academics in a UK post-1992, teaching-orientated university. Literature around academic identity suggests five major academic roles: teaching, research, management, writing and networking. However, this appears to be a picture of an established mid-career academic in a…

  17. Recombination of H-2 by Raman association in the early universe

    NARCIS (Netherlands)

    Dalgarno, A.; Loo, M.P.J. van der

    2006-01-01

    We investigate the contribution that Raman association makes to H-2 production in the early universe at redshifts 10 <= z <= 10(4). The Raman process involves inelastic scattering of electromagnetic radiation off two colliding hydrogen atoms, taking away kinetic and binding energy and leaving bound

  18. Learning and Developing as a University Teacher: Narratives of Early Career Academics in Estonia

    Science.gov (United States)

    Remmik, Marvi; Karm, Mari; Lepp, Liina

    2013-01-01

    In recent years the higher education context in Estonia, as in most European countries, has changed a lot. All changes have an impact on university teachers' practice and their work organisation, and are presenting new challenges. The current research aims at developing an understanding of Estonian early career academics' professional identity by…

  19. Violation of the strong Huygen's principle and timelike signals from the early universe.

    Science.gov (United States)

    Blasco, Ana; Garay, Luis J; Martín-Benito, Mercedes; Martín-Martínez, Eduardo

    2015-04-10

    We analyze the implications of the violations of the strong Huygen's principle in the transmission of information from the early Universe to the current era via massless fields. We show that much more information reaches us through timelike channels (not mediated by real photons) than is carried by rays of light, which are usually regarded as the only carriers of information.

  20. Test Anxiety in Mathematics among Early Undergraduate Students in a British University in Malaysia

    Science.gov (United States)

    Karjanto, Natanael; Yong, Su Ting

    2013-01-01

    The level of test anxiety in mathematics subjects among early undergraduate students at the University of Nottingham Malaysia Campus is studied in this article. The sample consists of 206 students taking several mathematics modules who completed the questionnaires on test anxiety just before they entered the venue for midterm examinations. The…

  1. The Impact of Good Quality Instructions of Early Education on the Performance of University Newcomers

    Science.gov (United States)

    AL-Othman, F. H.

    2014-01-01

    Good quality instruction in the early years of education has a positive impact in helping newcomers in universities and colleges to adapt to the new environment. This concept is widely applied in contemporary higher education because of the numerous benefits it offers to the students and the instructors. It, is not therefore, subject to the…

  2. On the chaoticity of active-sterile neutrino oscillations in the early universe

    DEFF Research Database (Denmark)

    Braad, Poul-Erik; Hannestad, Steen

    2000-01-01

    We have investigated the evolution of the neutrino asymmetry in active-sterile neutrino oscillations in the early universe. We find that there are large regions of parameter space where the asymmetry is extremely sensitive to variations in the initial asymmetry as well as the external parameters...

  3. Active-sterile neutrino oscillations in the early Universe with full collision terms

    DEFF Research Database (Denmark)

    Hannestad, Steen; Hansen, Rasmus Sloth; Tram, Thomas;

    2015-01-01

    Sterile neutrinos are thermalised in the early Universe via oscillations with the active neutrinos for certain mixing parameters. The most detailed calculation of this thermalisation process involves the solution of the momentum-dependent quantum kinetic equations, which track the evolution...

  4. Early star-forming galaxies and the reionization of the Universe.

    Science.gov (United States)

    Robertson, Brant E; Ellis, Richard S; Dunlop, James S; McLure, Ross J; Stark, Daniel P

    2010-11-04

    Star-forming galaxies trace cosmic history. Recent observational progress with the NASA Hubble Space Telescope has led to the discovery and study of the earliest known galaxies, which correspond to a period when the Universe was only ∼800 million years old. Intense ultraviolet radiation from these early galaxies probably induced a major event in cosmic history: the reionization of intergalactic hydrogen.

  5. Hangout With CERN: Hot stuff - the early Universe (S01E06)

    CERN Multimedia

    Kahle, Kate

    2012-01-01

    This Hangout takes us well into the past, as we delve into the very early Universe. The LHC can recreate these early-Universe conditions in the lab by colliding heavy ions together. But why do we collide these different particle species? What is in store for the heavy-ion collisions after the end-of-year break? What is this mysterious quark-gluon plasma? CERN's Quantum Diaries blogger and ATLAS physicist Pauline Gagnon is joined by theorists Urs Wiedemann and Stefan Floerchinger, as well as experts from the LHC's heavy-ion experiment, ALICE: Despina Hatzifotiadou, Antonin Maire, David Dobrigkeit Chinellato, Leticia Cunqueiro Mendez and Kenneth Read. Also connecting are ATLAS physicists Steven Goldfarb and Tiina Wickstroem from the Science Museum in London with content developer Alice Lighton, as well as Fraser Cain, publisher of Universe Today. Recorded live on 6th December 2012.

  6. Cosmological Imprints of a Generalized Chaplygin Gas Model for the Early Universe

    Energy Technology Data Exchange (ETDEWEB)

    Bouhmadi-Lopez, Mariam; /Lisbon, CENTRA; Chen, Pisin; /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC; Liu, Yen-Wei; /Taiwan, Natl. Taiwan U.

    2012-06-06

    We propose a phenomenological model for the early universe where there is a smooth transition between an early quintessence phase and a radiation-dominated era. The matter content is modeled by an appropriately modified Chaplygin gas for the early universe. We constrain the model observationally by mapping the primordial power spectrum of the scalar perturbations to the latest data of WMAP7. We compute as well the spectrum of the primordial gravitational waves as would be measured today. We show that the high frequencies region of the spectrum depends on the free parameter of the model and most importantly this region of the spectrum can be within the reach of future gravitational waves detectors.

  7. Carbon Ion Therapy for Early-Stage Non-Small-Cell Lung Cancer

    Directory of Open Access Journals (Sweden)

    Yusuke Demizu

    2014-01-01

    Full Text Available Carbon ion therapy is a type of radiotherapies that can deliver high-dose radiation to a tumor while minimizing the dose delivered to the organs at risk; this profile differs from that of photon radiotherapy. Moreover, carbon ions are classified as high-linear energy transfer radiation and are expected to be effective for even photon-resistant tumors. Recently, high-precision radiotherapy modalities such as stereotactic body radiotherapy (SBRT, proton therapy, and carbon ion therapy have been used for patients with early-stage non-small-cell lung cancer, and the results are promising, as, for carbon ion therapy, local control and overall survival rates at 5 years are 80–90% and 40–50%, respectively. Carbon ion therapy may be theoretically superior to SBRT and proton therapy, but the literature that is currently available does not show a statistically significant difference among these treatments. Carbon ion therapy demonstrates a better dose distribution than both SBRT and proton therapy in most cases of early-stage lung cancer. Therefore, carbon ion therapy may be safer for treating patients with adverse conditions such as large tumors, central tumors, and poor pulmonary function. Furthermore, carbon ion therapy may also be suitable for dose escalation and hypofractionation.

  8. Decoupling of carbon isotope records between organic matter and carbonate prior to the Toarcian Oceanic Anoxic Event (Early Jurassic)

    Science.gov (United States)

    Bodin, Stephane; Kothe, Tim; Krencker, Francois-Nicolas; Suan, Guillaume; Heimhofer, Ulrich; Immenhauser, Adrian

    2014-05-01

    Across the Pliensbachian-Toarcian boundary (P-To, Early Jurassic), ca. 1 Myr before the Toarcian Oceanic Anoxic Event (T-OAE), an initial negative carbon isotope excursion has been documented in western Tethys sedimentary rocks. In carbonate, its amplitude (2-3 permil) is similar to the subsequent excursion recorded at the onset of the T-OAE. Being also associated with a rapid warming event, the significance of this first carbon isotope shift, in terms of paleoenvironmental interpretation and triggering mechanism, remains however elusive. Taking advantage of expanded and rather continuous sections in the High Atlas of Morocco, several high-resolution, paired organic-inorganic carbon isotope records have been obtained across the Upper Pliensbachian - Lower Toarcian interval. At the onset of the T-OAE, an abrupt 1-2 permil negative shift is recorded in both organic and inorganic phases, succeeded by a relatively longer term 1-2 permil negative trend and a final slow return to pre-excursion conditions. In accordance with previous interpretations, this pattern indicates a perturbation of the entire exogenic carbon isotope reservoir at the onset of the T-OAE by the sudden release of isotopically light carbon into the atmosphere. By contrast, there is no negative shift in carbon isotopes for the P-To event recorded in bulk organic matter of Morocco. Given the strong dominance of terrestrial particles in the bulk organic matter fraction, this absence indicates that massive input of 12C-rich carbon into the atmosphere is not likely to have happened during the P-To event. A pronounced (2 permil) and abrupt negative shift in carbon isotope is however recorded in the bulk carbonate phase. We suggest that this decoupling between organic and inorganic phase is due to changes in the nature of the bulk carbonate phase. Indeed, the negative shift occurs at the lithological transition between Pliensbachian-lowermost Toarcian limestone-marl alternations and the Lower Toarcian marl

  9. Stellar production rates of carbon and its abundance in the universe

    CERN Document Server

    Oberhummer, Heinz; Schlattl, H; Oberhummer, Heinz; Csoto, Attila; Schlattl, Helmut

    2000-01-01

    The bulk of the carbon in our universe is produced in the triple-alpha process in helium-burning red giant stars. We calculated the change of the triple-alpha reaction rate in a microscopic 12-nucleon model of the C-12 nucleus and looked for the effects of minimal variations of the strengths of the underlying interactions. Stellar model calculations were performed with the alternative reaction rates. Here, we show that outside a narrow window of 0.5 and 4% of the values of the strong and Coulomb forces, respectively, the stellar production of carbon or oxygen is reduced by factors of 30 to 1000.

  10. Early viscous universe with variable gravitational and cosmological 'constants'

    Energy Technology Data Exchange (ETDEWEB)

    Singh, C P [Department of Applied Mathematics, Delhi College of Engineering, Bawana Road, Delhi-110 042 (India); Kumar, Suresh [Department of Applied Mathematics, Delhi College of Engineering, Bawana Road, Delhi-110 042 (India); Pradhan, A [Department of Mathematics, Hindu Post-Graduate College, Zamania, Ghazipur-232 331 (India)

    2007-01-21

    Einstein's field equations with variable gravitational and cosmological 'constants' are considered in the presence of bulk viscosity for a spatially flat homogeneous and isotropic universe. Solutions are obtained by using a 'gamma-law' equation of state p = ({gamma} - 1){rho}, where the adiabatic parameter {gamma} varies continuously as the universe expands. A unified description of the early evolution of universe is presented with a number of possible assumptions on the bulk viscous term and gravitational constant in which an inflationary phase is followed by radiation-dominated phase. We investigate the cosmological model with constant and time-dependent bulk viscosity (proportional to power function of energy density and to Hubble parameter) along with constant and variable gravitational constant. The effect of viscosity is shown to affect the past and future of the universe. In all cases, the cosmological constant {lambda} is found to be positive and a decreasing function of time, which supports the results obtained from recent supernovae Ia observations. The possibility that the present acceleration of the universe is driven by a kind of viscous fluid is explained. At the background level this model is similar to the generalized Chaplygin gas model. The physical and geometrical significance of the early cosmological models has also been discussed.

  11. Time variation of the electron mass in the early universe and the Barrow-Magueijo model

    CERN Document Server

    Scóccola, Claudia G; Landau, Susana J; Vucetich, Héctor

    2008-01-01

    We put limits on the time variation of the electron mass in the early universe using observational primordial abundances of D, He4 and Li7, recent data from the Cosmic Microwave Background and the 2dFGRS power spectrum. Furthermore, we use these constraints together with other astronomical and geophysical bounds from the late universe to test Barrow-Magueijo's model for the variation in m_e. From our analysis we obtain -0.615 < G\\omega/c^4 < -0.045 (3\\sigma interval) in disagreement with the result obtained in the original paper.

  12. Universality and diversity in a phonon-transmission histogram of isotope-disordered carbon nanotubes.

    Science.gov (United States)

    Yamamoto, Takahiro; Sasaoka, Kenji; Watanabe, Satoshi

    2011-05-27

    Universal fluctuations in phonon transmission and other features of phonon-transmission histograms are investigated by performing numerical simulations of coherent-phonon transport in isotope-disordered carbon nanotubes. Interestingly, the phonon-transmission fluctuation in the diffusive regime is universal, irrespective of the average phonon transmission, the tube chirality, and the concentrations, and masses of isotopes. We also find that the histogram, which has a Gaussian distribution in the diffusive regime, has a log-normal distribution in the localization regime. © 2011 American Physical Society

  13. From Early Aspirations to Actual Attainment: The Effects of Economic Status and Educational Expectations on University Pursuit

    Science.gov (United States)

    Wu, Ching-Ling; Bai, Haiyan

    2015-01-01

    This study investigated the effects of economic status and the educational expectations of significant others on early university aspirations and actual university attainment. The study analyzed two-wave longitudinal data collected from 1,595 Taiwanese students in their 9th grade in middle school and in their freshman year at universities. The…

  14. Baryogenesis, Dark Matter and the Maximal Temperature of the Early Universe

    CERN Document Server

    Buchmuller, Wilfried

    2012-01-01

    Mechanisms for the generation of the matter-antimatter asymmetry and dark matter strongly depend on the reheating temperature T_R, the maximal temperature reached in the early universe. Forthcoming results from the LHC, low energy experiments, astrophysical observations and the Planck satellite will significantly constrain baryogenesis and the nature of dark matter, and thereby provide valuable information about the very early hot universe. At present, a wide range of reheating temperatures is still consistent with observations. We illustrate possible origins of matter and dark matter with four examples: moduli decay, electroweak baryogenesis, leptogenesis in the nuMSM and thermal leptogenesis. Finally, we discuss the connection between baryogenesis, dark matter and inflation in the context of supersymmetric spontaneous B-L breaking.

  15. Baryogenesis, dark matter and the maximal temperature of the early universe

    Energy Technology Data Exchange (ETDEWEB)

    Buchmueller, Wilfried

    2012-12-15

    Mechanisms for the generation of the matter-antimatter asymmetry and dark matter strongly depend on the reheating temperature T{sub R}, the maximal temperature reached in the early universe. Forthcoming results from the LHC, low energy experiments, astrophysical observations and the Planck satellite will significantly constrain baryogenesis and the nature of dark matter, and thereby provide valuable information about the very early hot universe. At present, a wide range of reheating temperatures is still consistent with observations. We illustrate possible origins of matter and dark matter with four examples: moduli decay, electroweak baryogenesis, leptogenesis in the {nu}MSM and thermal leptogenesis. Finally, we discuss the connection between baryogenesis, dark matter and inflation in the context of supersymmetric spontaneous B-L breaking.

  16. Early Cretaceous CO2 Pulses: Trigger of Carbon Cycle Perturbations and of Biocalcification Crises

    Science.gov (United States)

    Weissert, H.; Wissler, L.; Hennig, S.

    2003-04-01

    The Early Cretaceous C-isotope curve is marked by several positive carbon isotope anomalies with an amplitude of 2-3 ppm and lasting up to millions of years. The two most prominent of these excursions are of Late Valanginian and Aptian age. Isotopic mass balance models suggest that positive carbon isotope excursions reflect altered partitioning of carbon between the oxidized and reduced carbon sinks and that these changes occurred in response to elevated atmospheric CO_2 levels and coupled climate change. Both carbon isotope anomalies coincide with episodes of increased volcanic activity, which is regarded as the source of excess atmospheric carbon dioxide. The Aptian carbon isotope anomaly is preceded by a short-lived negative carbon isotope pulse of up to 2 ppm amplitude while a comparable pulse is not recognized at the base of the Valanginian carbon isotope excursion. This C- isotope event may record a climate-induced destabilisation of sedimentary gas hydrates and the sudden release of methane to oceans and atmosphere. Both, the Aptian and the Valanginian carbon isotope excursions are accompanied by biocalcification crises on carbonate platforms and in pelagic environments. The Valanginian carbonate platform drowning, the nannoconid crisis and the disappearance of calpionellids coincide with the beginning of the positive carbon isotope anomaly. The Aptian biocalcification crises on platforms and in pelagic environments started before the negative carbon isotope spike. Both crises in biocalcification may have been triggered by p CO_2-induced changes in surface water chemistry and/or by sudden changes in temperatures and/or by changes in nutrient levels. Available paleoclimate data and the bulk oxygen isotope records show no evidence for major low latitude ocean paleotemperature changes at the base of the Valanginian isotope anomaly. Partial choking of carbonate production during the Aptian occurred at a time of decreasing oxygen isotope values in pelagic bulk

  17. Hadronic Matter in the Robertson-Walker Metric and the Early Universe

    CERN Document Server

    Cunha, Ivan E

    2015-01-01

    In this work, the Friedman equations for hadronic matter in the Robertson-Walker metric in the early Universe are obtained. We consider the hadronic phase, formed after the hadronization of the quark-gluon plasma, that means times from 10^{-6}s to 1s. The set of equations is derived and the behavior of the system is studied considering one approximate analytical solution.

  18. Origins and Missions of Two Early Land-Grant Colleges: Georgetown University and George Washington University. ASHE Annual Meeting 1980 Paper.

    Science.gov (United States)

    Quigley, Martin S.

    The founding and missions of Georgetown University and George Washington University, two early land-grant colleges, are considered. The account is based partially on standard histories of the colleges, and other information comes from Congressional Records. Some understanding of why Congress took an interest in the founding and survival of…

  19. A Class of LQC--inspired Models for Homogeneous, Anisotropic Cosmology in Higher Dimensional Early Universe

    CERN Document Server

    Rama, S Kalyana

    2016-01-01

    The dynamics of a (3 + 1) dimensional homogeneous anisotropic universe is modified by Loop Quantum Cosmology and, consequently, it has generically a big bounce in the past instead of a big-bang singularity. This modified dynamics can be well described by effective equations of motion. We generalise these effective equations of motion empirically to (d + 1) dimensions. The generalised equations involve two functions and may be considered as a class of LQC -- inspired models for (d + 1) dimensional early universe cosmology. As a special case, one can now obtain a universe which has neither a big bang singularity nor a big bounce but approaches asymptotically a `Hagedorn like' phase in the past where its density and volume remain constant. In a few special cases, we also obtain explicit solutions.

  20. A class of LQC-inspired models for homogeneous, anisotropic cosmology in higher dimensional early universe

    Science.gov (United States)

    Rama, S. Kalyana

    2016-12-01

    The dynamics of a (3 + 1) dimensional homogeneous anisotropic universe is modified by loop quantum cosmology and, consequently, it has generically a big bounce in the past instead of a big-bang singularity. This modified dynamics can be well described by effective equations of motion. We generalise these effective equations of motion empirically to (d + 1) dimensions. The generalised equations involve two functions and may be considered as a class of LQC-inspired models for (d + 1) dimensional early universe cosmology. As a special case, one can now obtain a universe which has neither a big bang singularity nor a big bounce but approaches asymptotically a `Hagedorn like' phase in the past where its density and volume remain constant. In a few special cases, we also obtain explicit solutions.

  1. Large-scale structure from quantum fluctuations in the early universe

    Energy Technology Data Exchange (ETDEWEB)

    Michael Turner

    2000-05-25

    A better understanding of the formation of large-scale structure in the Universe is arguably the most pressing question in cosmology. The most compelling and promising theoretical paradigm, Inflation + Cold Dark Matter, holds that the density inhomogeneities that seeded the formation of structure in the Universe originated from quantum fluctuations arising during inflation and that the bulk of the dark matter exists as slowing moving elementary particles (cold dark matter) left over from the earliest, fiery moments. Large redshift surveys (such as the SDSS and 2dF) and high-resolution measurements of CBR anisotropy (to be made by the MAP and Planck Surveyor satellites) have the potential to decisively test Inflation + Cold Dark Matter and to open a window to the very early Universe and fundamental physics.

  2. Universal and targeted early home visiting: perspectives of public health nurses, managers and mothers

    Directory of Open Access Journals (Sweden)

    Megan Aston

    2014-07-01

    Full Text Available Early home visits provided by public health nurses (PHNs around the world have been proven to positively impact physical, social, emotional and mental health outcomes of mothers and babies. Most of the research has focused on home visiting programs delivered by public health nurses and lay home visitors to support at risk or targeted mothers. Little research has been conducted to examine universal home visiting programs for mothers who are perceived to be lower-risk. The purpose of this research was to explore how universal and targeted early home visiting programs for mothers and babies were organized, delivered and experienced through the everyday practices of PHNs, mothers, and managers in one city in Atlantic Canada. Feminist post-structuralism was used to collect and analyze data through semi-structured face-to-face interviews with 16 PHNs, 16 mothers and 4 managers. Personal, social and institutional discourses of program delivery were examined using discourse analysis. Four main themes of the study include: i understanding targeted and universal programming; ii health outcomes; iii building relationships; and iv exploring a new surveillance. This article will discuss the first theme; understanding targeted and universal programming.

  3. Carbon nanotubes as VEGF carriers to improve the early vascularization of porcine small intestinal submucosa in abdominal wall defect repair

    Directory of Open Access Journals (Sweden)

    Liu Z

    2014-03-01

    Full Text Available Zhengni Liu,1,* Xueyi Feng,2,* Huichun Wang,1 Jun Ma,1 Wei Liu,3 Daxiang Cui,4 Yan Gu,1 Rui Tang,11Department of General Surgery, Shanghai Ninth People’s Hospital, Hernia and Abdominal Wall Disease Center, Shanghai Jiao Tong University School of Medicine, Shanghai, People’s Republic of China; 2Department of General Surgery, Lu’an People’s Hospital, Lu’an Affiliated Hospital of Anhui Medical University, Lu’an, Province Anhui, People’s Republic of China; 3Department of Plastic and Reconstructive Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Tissue Engineering, Shanghai, People’s Republic of China; 4Institute of Nano Biomedicine and Engineering, Key Laboratory for Thin Film and Microfabrication Technology of the Ministry of Education, Research Institute of Micro/Nano Science and Technology, Bio-X Center, Shanghai Jiao Tong University, Shanghai, People's Republic of China *These authors contributed equally to this work Abstract: Insufficient early vascularization in biological meshes, resulting in limited host tissue incorporation, is thought to be the primary cause for the failure of abdominal wall defect repair after implantation. The sustained release of exogenous angiogenic factors from a biocompatible nanomaterial might be a way to overcome this limitation. In the study reported here, multiwalled carbon nanotubes (MWNT were functionalized by plasma polymerization to deliver vascular endothelial growth factor165 (VEGF165. The novel VEGF165-controlled released system was incorporated into porcine small intestinal submucosa (PSIS to construct a composite scaffold. Scaffolds incorporating varying amounts of VEGF165-loaded functionalized MWNT were characterized in vitro. At 5 weight percent MWNT, the scaffolds exhibited optimal properties and were implanted in rats to repair abdominal wall defects. PSIS scaffolds incorporating VEGF165-loaded MWNT (VEGF

  4. Carbon isotopic composition of fossil leaves from the Early Cretaceous sediments of western India

    Indian Academy of Sciences (India)

    S Chakraborty; B N Jana; S K Bhattacharya; I Robertson

    2011-08-01

    Stable carbon isotope analysis of fossil leaves from the Bhuj Formation, western India was carried out to infer the prevailing environmental conditions. Compression fossil leaves such as Pachypteris indica, Otozamite kachchhensis, Brachyphyllum royii and Dictyozamites sp. were recovered from three sedimentary successions of the Bhuj Formation, Early Cretaceous in age. A chronology was established based on faunal assemblage and palyno-stratigraphy and further constrained by carbon isotope stratigraphy. The three sampling sites were the Karawadi river bank near Dharesi; the Chawad river bank near Mathal; and the Pur river section near Trambau village in Gujarat. The Dharesi sample was also analyzed to investigate intra-leaf 13C variability. The mean 13C of the leaf was −24.6 ± 0.4‰ which implied negligible systematic change along the leaf axis. The Mathal sample was fragmented in nature and showed considerable variation in carbon isotopic composition. The Trambau sample considered to be the oldest, dating to the middle of Aptian (ca. 116 Ma), shows the most depleted value in 13C among all of them. The overall 13C trend ranging from mid Aptian (ca. 116 Ma) to early Albian (ca. 110 Ma) shows a progressive increase in 13C from −26.8 to −20.5‰. Based on these measurements the carbon isotopic composition of atmospheric carbon dioxide of the Aptian–Albian period is estimated to be between −7.4 and −1.7‰. The ratio of the partial pressure of carbon dioxide in leaf to that of the ambient atmosphere calculated based on a model is estimated to be similar to that of the modern plants. This indicates that the Early-Cretaceous plants adapted to the prevailing high carbon dioxide regime by increasing their photosynthetic uptake.

  5. Earth's Early Biosphere and the Biogeochemical Carbon Cycle

    Science.gov (United States)

    DesMarais, David

    2004-01-01

    Our biosphere has altered the global environment principally by influencing the chemistry of those elements most important for life, e g., C, N, S, O, P and transition metals (e.g., Fe and Mn). The coupling of oxygenic photosynthesis with the burial in sediments of photosynthetic organic matter, and with the escape of H2 to space, has increased the state of oxidation of the Oceans and atmosphere. It has also created highly reduced conditions within sedimentary rocks that have also extensively affected the geochemistry of several elements. The decline of volcanism during Earth's history reduced the flow of reduced chemical species that reacted with photosynthetically produced O2. The long-term net accumulation of photosynthetic O2 via biogeochemical processes has profoundly influenced our atmosphere and biosphere, as evidenced by the O2 levels required for algae, multicellular life and certain modem aerobic bacteria to exist. When our biosphere developed photosynthesis, it tapped into an energy resource that was much larger than the energy available from oxidation-reduction reactions associated with weathering and hydrothermal activity. Today, hydrothermal sources deliver globally (0.13-1.1)x10(exp l2) mol yr(sup -1) of reduced S, Fe(2+), Mn(2+), H2 and CH4; this is estimated to sustain at most about (0.2-2)xl0(exp 12)mol C yr(sup -1) of organic carbon production by chemautotrophic microorganisms. In contrast, global photosynthetic productivity is estimated to be 9000x10(exp 12) mol C yr(sup -1). Thus, even though global thermal fluxes were greater in the distant geologic past than today, the onset of oxygenic photosynthesis probably increased global organic productivity by some two or more orders of magnitude. This enormous productivity materialized principally because oxygenic photosynthesizers unleashed a virtually unlimited supply of reduced H that forever freed life from its sole dependence upon abiotic sources of reducing power such as hydrothermal emanations

  6. Earth's Early Biosphere and the Biogeochemical Carbon Cycle

    Science.gov (United States)

    DesMarais, David

    2004-01-01

    Our biosphere has altered the global environment principally by influencing the chemistry of those elements most important for life, e g., C, N, S, O, P and transition metals (e.g., Fe and Mn). The coupling of oxygenic photosynthesis with the burial in sediments of photosynthetic organic matter, and with the escape of H2 to space, has increased the state of oxidation of the Oceans and atmosphere. It has also created highly reduced conditions within sedimentary rocks that have also extensively affected the geochemistry of several elements. The decline of volcanism during Earth's history reduced the flow of reduced chemical species that reacted with photosynthetically produced O2. The long-term net accumulation of photosynthetic O2 via biogeochemical processes has profoundly influenced our atmosphere and biosphere, as evidenced by the O2 levels required for algae, multicellular life and certain modem aerobic bacteria to exist. When our biosphere developed photosynthesis, it tapped into an energy resource that was much larger than the energy available from oxidation-reduction reactions associated with weathering and hydrothermal activity. Today, hydrothermal sources deliver globally (0.13-1.1)x10(exp l2) mol yr(sup -1) of reduced S, Fe(2+), Mn(2+), H2 and CH4; this is estimated to sustain at most about (0.2-2)xl0(exp 12)mol C yr(sup -1) of organic carbon production by chemautotrophic microorganisms. In contrast, global photosynthetic productivity is estimated to be 9000x10(exp 12) mol C yr(sup -1). Thus, even though global thermal fluxes were greater in the distant geologic past than today, the onset of oxygenic photosynthesis probably increased global organic productivity by some two or more orders of magnitude. This enormous productivity materialized principally because oxygenic photosynthesizers unleashed a virtually unlimited supply of reduced H that forever freed life from its sole dependence upon abiotic sources of reducing power such as hydrothermal emanations

  7. Contribution of chloroplast biogenesis to carbon-nitrogen balance during early leaf development in rice.

    Science.gov (United States)

    Kusumi, Kensuke; Hirotsuka, Shoko; Shimada, Hiroshi; Chono, Yoko; Matsuda, Osamu; Iba, Koh

    2010-07-01

    Chloroplast biogenesis is most significant during the changes in cellular organization associated with leaf development in higher plants. To examine the physiological relationship between developing chloroplasts and host leaf cells during early leaf development, we investigated changes in the carbon and nitrogen contents in leaves at the P4 developmental stage of rice, during which leaf blade structure is established and early events of chloroplast differentiation occur. During the P4 stage, carbon content on a dry mass basis remained constant, whereas the nitrogen content decreased by 30%. Among carbohydrates, sucrose and starch accumulated to high levels early in the P4 stage, and glucose, fructose and cellulose degradation increased during the mid-to-late P4 stage. In the chloroplast-deficient leaves of the virescent-1 mutant of rice, however, the carbon and nitrogen contents, as well as the C/N ratio during the P4 stage, were largely unaffected. These observations suggest that developing rice leaves function as sink organs at the P4 stage, and that chloroplast biogenesis and carbon and nitrogen metabolism in the leaf cell is regulated independently at this stage.

  8. The Hubble parameter in the early universe with viscous QCD matter and finite cosmological constant

    CERN Document Server

    Tawfik, A

    2011-01-01

    The evolution of a flat, isotropic and homogeneous universe is studied. The background geometry in the early phases of the universe is conjectured to be filled with causal bulk viscous cosmological fluid and dark energy. The energy density relations obtained from the assumption of covariant conservation of energy-momentum tensor of the background matter in the early universe are used to derive the basic equation for the Hubble parameter $H$. The viscous properties described by ultra-relativistic equations of state and bulk viscosity taken from recent heavy-ion collisions and lattice QCD calculations have been utilized to give an approximate solution of the field equations. The cosmological constant is conjectured to be related to the energy density of the vacuum. In this treatment, there is a clear evidence for singularity at vanishing cosmic time $t$ indicating the dominant contribution from the dark energy. The time evolution of $H$ seems to last for much longer time than the ideal case, where both cosmolog...

  9. The Hubble parameter in the early universe with viscous QCD matter and finite cosmological constant

    Energy Technology Data Exchange (ETDEWEB)

    Tawfik, A. [Egyptian Center for Theoretical Physics (ECTP), MTI University, Cairo (Egypt)

    2011-05-15

    The evolution of a flat, isotropic and homogeneous universe is studied. The background geometry in the early phases of the universe is conjectured to be filled with causal bulk viscous fluid and dark energy. The energy density relations obtained from the assumption of covariant conservation of energy-momentum tensor of the background matter in the early universe are used to derive the basic equation for the Hubble parameter H. The viscous properties described by ultra-relativistic equations of state and bulk viscosity taken from recent heavy-ion collisions and lattice QCD calculations have been utilized to give an approximate solution of the field equations. The cosmological constant is conjectured to be related to the energy density of the vacuum. In this treatment, there is a clear evidence for singularity at vanishing cosmic time t indicating the dominant contribution from the dark energy. The time evolution of H seems to last for much longer time than the ideal case, where both cosmological constant and viscosity coefficient are entirely vanishing. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Awareness of Skin Cancer, Prevention, and Early Detection among Turkish University Students

    Directory of Open Access Journals (Sweden)

    Ziyafet Ugurlu

    2016-01-01

    Full Text Available Objective: The aim of this study was to determine the awareness about skin cancer, prevention, and early detection among university students. Methods: This descriptive cross-sectional study was carried out with 404 students in a university located in Ankara, the capital city of Turkey. A 35-item questionnaire was used for data collection. Results: Less than half of the students (37.9% had knowledge about skin cancer mostly through the internet (24.5% and media (24.1%. Half of them aware of the risk factors; mostly as avoiding direct exposure to the Sun between 10 am and 4 pm (45.3%; smoking and alcohol (38.4%; having fair skin color (34.9%; and ultraviolet light exposure (25.7%. Only one-third of them (32.9% are knowledgeable about skin cancer signs and symptoms, such as a change in color and appearance of the nevus/moles (24%. The majority of the responders (77.3% did not know about screening tests for skin cancer and only 18 (4.5% students were practicing skin self-examination. Conclusions: This study showed a lack of knowledge about skin cancer, prevention, and early detection among university students and reported the need for educational interventions to raise awareness in this target group.

  11. Green Peas emit X-rays: Extreme Star Formation in Early Universe Analog Galaxies

    Science.gov (United States)

    Brorby, Matthew; Kaaret, Philip

    2017-01-01

    Luminous compact galaxies (LCGs), Lyman Alpha Emitters (LAEs), and Lyman Break Analog galaxies (LBAs) are all used as proxies for star-forming galaxies in the early Universe (z ≥ 6). The X-ray emission from such galaxies has been found to be elevated compared to other star-forming galaxies in our local Universe. It has been suggested that this may be due to the lower metallicity seen in these proxies to high-redshift galaxies and the elevated X-ray emission may affect the heating and Reionization evolution of the early Universe. Our previous studies have suggested the existence of an LX-SFR-metallicity plane for all star-forming galaxies. We present these results in the context of our newest Joint Chandra/HST study containing the first X-ray detection of the Green Pea galaxies, a population of compact starburst galaxies discovered by volunteers in the Galaxy Zoo Project (Cardamone+2009). The galaxies were given the name Green Peas due to their compact size and green appearance in the gri composite images from SDSS. The green color is caused by a strong [OIII]λ5007Å emission line, an indicator of recent star formation. We observed a few of the most promising candidates with joint Chandra/HST observation and discuss our findings here.

  12. The Emergence of Pelagic Carbonate Production by Nannoplankton in The Early Jurassic

    Science.gov (United States)

    Mattioli, E.; Pittet, B.; Suan, G.; Sucheras-Marx, B.; Reggiani, L.; Planck, J.

    2008-12-01

    Coccolithophores are among the main carbonate producers in today's Oceans. They participate to the organic-carbon pump and carbonate counter-pump at the same time, and therefore have a fundamental role in the carbon cycle. In this regard, the first occurrence and subsequent diversification of calcareous nannoplankton and in particular of coccolithophorids (225-65 Mya) likely had a major impact on biogeochemical cycles and the regulation of pCO2 in the atmosphere/hydrosphere. Nevertheless, both causes and consequences of the emergence of calcareous nannoplankton between the Late Triassic and the Early Jurassic remain poorly understood. In order to address the possible relationships between the early diversification of coccolithopororids and the evolution of atmospheric CO2 conditions, we performed a quantitative micropaleontological study in the well-exposed sections outcropping along the west coast of Portugal, spanning the entire Lower Jurassic. The accumulation rates of pelagic carbonates were reconstructed using the absolute abundances and size estimates of the most important pelagic carbonate producers as well as the cyclostratigraphic calibration of the studied successions. Our results show that nannofossil absolute abundance, although fluctuating in the Early Jurassic, increased by discrete steps. The first step (up to 0.2 billion of nannofossils per gram of rock) occurred at the base of the Late Pliensbachian and coincided with the deposition of organic matter-rich sediments. A second, more important increase is recorded at the Pliensbachian/Toarcian transition (-183 Mya), when absolute abundance attained values of 1.1 billion of nannofossils per gram of rock. These abundances are comparable to the record of surface sediments deposited under oligotrophic conditions. The following decrease in coccolithophorids observed during the Early Toarcian oceanic anoxic event is particularly intriguing. The dramatic decrease or loss of biocalcification potential could

  13. Testing Early Universe Theories Using Large Scale Structure: Moving Beyond Phenomenology

    Science.gov (United States)

    Shandera, Sarah

    Current observational evidence favors inflation, a very early era of accelerated expansion, as the origin of the Large Scale Structure of the universe. Although compelling, this evidence comes mainly from the amplitude of primordial perturbations as a function of scale. More detailed and definitive information is contained in higher order statistics, collectively labelled `non- Gaussianity', which is of unparalleled importance to theorists who study inflation or its competitors. Analogously to collider physics studies, non-Gaussianity probes the interactions of the fields active in the very early universe and so will allow us to uncover the particle physics identity of the components that give rise to the very early pattern of density fluctuations. Primordial non-Gaussianity generates many non-trivial signals in Large Scale Structure, thanks largely to the non-linear evolution of the primordial perturbations. The distribution of objects in mass and redshift and their spatial clustering together contain information about the complete set of statistics of the primordial fluctuations. Predictions for those observables rely on numerical simulations of the dark matter evolution, which so far have been carried out almost entirely for a simple phenomenological model of primordial non-Gaussianity. However, it is now clear that interesting constraints or detection of non-Gaussianity are possible with next generation surveys: to use this data to its fullest extent we must understand clearly what those constraints will mean for fundamental theories of the origin of the perturbations. We propose to make a direct connection between theoretical ideas for the primordial fluctuations, including non-Gaussianity, and predictions from those theories for details of the Large Scale Structure of the Universe. Our goal is to find a prescription for setting up initial conditions for N-body simulations that match as closely as possible the predictions from a variety of particle physics

  14. Neutrinos in the Early Universe, Kalb-Ramond Torsion and Matter-Antimatter Asymmetry

    Directory of Open Access Journals (Sweden)

    Mavromatos Nick E.

    2014-04-01

    Full Text Available The generation of a matter-antimatter asymmetry in the universe may be induced by the propagation of fermions in non-trivial, spherically asymmetric (and hence Lorentz violating gravitational backgrounds. Such backgrounds may characterise the epoch of the early universe. The key point in these models is that the background induces di_erent dispersion relations, hence populations, between fermions and antifermions, and thus CPT Violation (CPTV appears in thermal equilibrium. Species populations may freeze out leading to leptogenesis and baryogenesis. We consider here a string-inspired scenario, in which the CPTV is associated with a cosmological background with torsion provided by the Kalb-Ramond (KR antisymemtric tensor field of the string gravitational multiplet. In a four-dimensional space time this field is dual to a pseudoscalar “axionlike” field. The mixing of the KR field with an ordinary axion field can lead to the generation of a Majorana neutrino mass.

  15. Rapid growth of seed black holes in the early universe by supra-exponential accretion.

    Science.gov (United States)

    Alexander, Tal; Natarajan, Priyamvada

    2014-09-12

    Mass accretion by black holes (BHs) is typically capped at the Eddington rate, when radiation's push balances gravity's pull. However, even exponential growth at the Eddington-limited e-folding time t(E) ~ few × 0.01 billion years is too slow to grow stellar-mass BH seeds into the supermassive luminous quasars that are observed when the universe is 1 billion years old. We propose a dynamical mechanism that can trigger supra-exponential accretion in the early universe, when a BH seed is bound in a star cluster fed by the ubiquitous dense cold gas flows. The high gas opacity traps the accretion radiation, while the low-mass BH's random motions suppress the formation of a slowly draining accretion disk. Supra-exponential growth can thus explain the puzzling emergence of supermassive BHs that power luminous quasars so soon after the Big Bang.

  16. Rapid growth of seed black holes in the early universe by supra-exponential accretion

    CERN Document Server

    Alexander, Tal

    2014-01-01

    Mass accretion by black holes (BHs) is typically capped at the Eddington rate, when radiation's push balances gravity's pull. However, even exponential growth at the Eddington-limited e-folding time t_E ~ few x 0.01 Gyr, is too slow to grow stellar-mass BH seeds into the supermassive luminous quasars that are observed when the universe is 1 Gyr old. We propose a dynamical mechanism that can trigger supra-exponential accretion in the early universe, when a BH seed is trapped in a star cluster fed by the ubiquitous dense cold gas flows. The high gas opacity traps the accretion radiation, while the low-mass BH's random motions suppress the formation of a slowly-draining accretion disk. Supra-exponential growth can thus explain the puzzling emergence of supermassive BHs that power luminous quasars so soon after the Big Bang.

  17. Gravitational Field of the Early Universe; 1, Non-linear Scalar Field as the Source

    CERN Document Server

    Chervon, S V

    1997-01-01

    In this review article we consider three most important sources of the gravitational field of the Early Universe: self-interacting scalar field, chiral field and gauge field. The correspondence between all of them are pointed out. More attention is payed to nonlinear scalar field source of gravity. The progress in finding the exact solutions in inflationary universe is reviewed. The basic idea of `fine turning of the potential' method is discussed and computational background is presented in details. A set of new exact solutions for standard inflationary model and conformally-flat space-times are obtained. Special attention payed to relations between `fine turning of the potential' and Barrow's approaches. As the example of a synthesis of both methods new exact solution is obtained.

  18. Effects of quantum gravity on the inflationary parameters and thermodynamics of the early universe

    CERN Document Server

    Tawfik, A; Ali, A Farag

    2014-01-01

    The effects of generalized uncertainty principle (GUP) on the inflationary dynamics and the thermodynamics of the early universe are studied. Using the GUP approach, the tensorial and scalar density fluctuations in the inflation era are evaluated and compared with the standard case. We find a good agreement with the Wilkinson Microwave Anisotropy Probe data. Assuming that a quantum gas of scalar particles is confined within a thin layer near the apparent horizon of the Friedmann-Lemaitre-Robertson-Walker universe which satisfies the boundary condition, the number and entropy densities and the free energy arising form the quantum states are calculated using the GUP approach. A qualitative estimation for effects of the quantum gravity on all these thermodynamic quantities is introduced.

  19. Effects of quantum gravity on the inflationary parameters and thermodynamics of the early universe

    Science.gov (United States)

    Tawfik, A.; Magdy, H.; Farag Ali, Ahmed

    2013-06-01

    The effects of generalized uncertainty principle (GUP) on the inflationary dynamics and the thermodynamics of the early universe are studied. Using the GUP approach, the tensorial and scalar density fluctuations in the inflation era are evaluated and compared with the standard case. We find a good agreement with the Wilkinson Microwave Anisotropy Probe data. Assuming that a quantum gas of scalar particles is confined within a thin layer near the apparent horizon of the Friedmann-Lemaitre-Robertson-Walker universe which satisfies the boundary condition, the number and entropy densities and the free energy arising form the quantum states are calculated using the GUP approach. A qualitative estimation for effects of the quantum gravity on all these thermodynamic quantities is introduced.

  20. A cryogenic liquid-mirror telescope on the moon to study the early universe

    CERN Document Server

    Angel, Roger; Borra, Ermanno F; Eisenstein, Daniel J; Foing, Bernard; Hickson, Paul; Josset, Jean-Luc; Ma, Ki Bui; Seddiki, Omar; Sivanandam, Suresh; Thibault, Simon; van Susante, Paul

    2008-01-01

    We have studied the feasibility and scientific potential of zenith observing liquid mirror telescopes having 20 to 100 m diameters located on the moon. They would carry out deep infrared surveys to study the distant universe and follow up discoveries made with the 6 m James Webb Space Telescope (JWST), with more detailed images and spectroscopic studies. They could detect objects 100 times fainter than JWST, observing the first, high-red shift stars in the early universe and their assembly into galaxies. We explored the scientific opportunities, key technologies and optimum location of such telescopes. We have demonstrated critical technologies. For example, the primary mirror would necessitate a high-reflectivity liquid that does not evaporate in the lunar vacuum and remains liquid at less than 100K: We have made a crucial demonstration by successfully coating an ionic liquid that has negligible vapor pressure. We also successfully experimented with a liquid mirror spinning on a superconducting bearing, as w...

  1. Berkeley Prize: Mapping the Fuel for Star Formation in Early Universe Galaxies

    Science.gov (United States)

    Tacconi, Linda

    2012-01-01

    Stars form from cold molecular interstellar gas, which is relatively rare in galaxies like the Milky Way, which form only a few new stars per year. Massive galaxies in the distant universe formed stars much more rapidly. Was star formation more efficient in the past, and/or were early galaxies richer in molecular gas? The answer was elusive when our instruments could probe molecules only in the most luminous and rare objects such as mergers and quasars. But a new survey of molecular gas in typical massive star-forming galaxies at redshifts from about 1.2 to 2.3 (corresponding to when the universe was 24% to 40% of its current age) reveals that distant star-forming galaxies were indeed molecular-gas rich and that the star-formation efficiency is not strongly dependent on cosmic epoch.

  2. Can Superconducting Cosmic Strings Piercing Seed Black Holes Generate Supermassive Black Holes in the Early Universe?

    CERN Document Server

    Lake, Matthew J

    2015-01-01

    The discovery of a large number of supermassive black holes at redshifts $z> 6$, when the Universe was only nine hundred million years old, has raised the fundamental question of how such massive compact objects could form in a (cosmologically) short time interval. Each of the proposed standard scenarios for black hole formation, involving rapid accretion of seed black holes, or black hole mergers, faces severe theoretical difficulties in explaining the short time formation of supermassive objects. In the present Letter, we propose an alternative scenario for the formation of supermassive black holes in the early Universe in which energy transfer from superconducting cosmic strings, piercing small seed black holes, is the main physical process leading to rapid mass increase. The increase in mass of a primordial seed black hole pierced by two antipodal strings is estimated and it is shown that this increases linearly in time. Due to the high energy transfer rate from the cosmic strings, we find that supermassi...

  3. Universal curves for the van der Waals interaction between single-walled carbon nanotubes.

    Science.gov (United States)

    Pogorelov, Evgeny G; Zhbanov, Alexander I; Chang, Yia-Chung; Yang, Sung

    2012-01-17

    We report very simple and accurate algebraic expressions for the van der Waals (VDW) potentials and the forces between two parallel and crossed carbon nanotubes. The Lennard-Jones potential for two carbon atoms and the method of the smeared-out approximation suggested by Girifalco were used. It is found that the interaction between parallel and crossed tubes is described by two universal curves for parallel and crossed configurations that do not depend on the van der Waals constants, the angle between tubes, and the surface density of atoms and their nature but only on the dimensionless distance. The explicit functions for equilibrium VDW distances, well depths, and maximal attractive forces have been given. These results may be used as a guide for the analysis of experimental data to investigate the interaction between nanotubes of various natures.

  4. Can primordial wormholes be induced by GUTs at the early Universe?

    CERN Document Server

    Nojiri, S; Odintsov, S D; Osetrin, K E

    1999-01-01

    Using large N, 4d anomaly induced one-loop effective action for conformally invariant matter (typical GUT multiplet) we study the possibility to induce the primordial spherically symmetric wormholes at the early Universe. The corresponding effective equations are obtained in two different coordinate frames. The numerical investigation of these equations is done for matter content corresponding to ${\\cal N}=4$ SU(N) super Yang-Mills theory. For some choice of initial conditions, the induced wormhole solution with increasing throat radius and increasing red-shift function is found.

  5. Quantum chromodynamics phase transition in the early Universe and quark nuggets

    Indian Academy of Sciences (India)

    Abhijit Bhattacharyya; Shibaji Banerjee; Sanjay K Ghosh; Sibaji Raha; Bikash Sinha; Hiroshi Toki

    2003-05-01

    A first-order quark hadron phase transition in the early Universe may lead to the formation of quark nuggets. The baryon number distribution of these quark nuggets have been calculated and it has been found that there are sizeable number of quark nuggets in the stable sector. The nuggets can clump and form bigger objects in the mass range of 0.0003$M_{\\odot}$ to 0.12$M_{\\odot}$. It has been discussed that these bigger objects can be possible candidates for cold dark matter.

  6. Phase Transitions in the Early Universe with Negatively Induced Supergravity Cosmological Constant

    Institute of Scientific and Technical Information of China (English)

    EL-NABULSI Ahmad Rami

    2006-01-01

    @@ We consider that the observable cosmological constant is the sum of the vacuum (Avac) and the induced term (Aind - 3m2/4) with m being the ultra-light masses (≈ Hubble parameter) implemented in the theory from supergravities arguments and non-minimal coupling. In the absence of a scalar buildup of matter fields, we study its effects on spontaneous symmetry breaking with a Higgs potential and show how the presence of the ultra-light masses yields some important consequences for the early universe and new constraints on the Higgs and electroweak gauge bosons masses.

  7. Molecular Hydrogen Formation in the Early Universe: New Implications From Laboratory Measurements

    Science.gov (United States)

    Miller, K. A.; Kreckel, H.; Bruhns, H.; Savin, D. W.; Urbain, X.; Čížek, M.; Glover, S. C. O.

    2011-05-01

    We have performed the first energy-resolved measurement of the associative detachment (AD) reaction H\\oline + H → H2 + e\\oline: This reaction is the dominant formation pathway for H2 during the epoch of first star formation in the early universe. Despite being the most fundamental anion-neutral chemical reaction, experiment and theory have failed to converge in both magnitude and energy dependence. The uncertainty in this rate coefficient severely limits our under- standing of the formation of the first stars and protogalaxies.

  8. The early universe history from contraction-deformation of the Standard Model

    Science.gov (United States)

    Gromov, N. A.

    2017-03-01

    The elementary particles evolution in the early Universe from Plank time up to several milliseconds is presented. The developed theory is based on the high-temperature (high-energy) limit of the Standard Model which is generated by the contractions of its gauge groups. At the infinite temperature all particles lose masses. Only massless neutral -bosons, massless Z-quarks, neutrinos and photons are survived in this limit. The weak interactions become long-range and are mediated by neutral currents, quarks have only one color degree of freedom.

  9. Proposed observations of gravity waves from the early Universe via "Millikan oil drops"

    CERN Document Server

    Chiao, R Y

    2006-01-01

    Pairs of Planck-mass drops of superfluid helium coated by electrons (i.e., ``Millikan oil drops''), when levitated in a superconducting magnetic trap, can be efficient quantum transducers between electromagnetic (EM) and gravitational (GR) radiation. This leads to the possibility of a Hertz-like experiment, in which EM waves are converted at the source into GR waves, and then back-converted at the receiver from GR waves back into EM waves. Detection of the gravity-wave analog of the cosmic microwave background using these drops can discriminate between various theories of the early Universe.

  10. Proposed Observations of Gravitational Waves from the Early Universe via "MILLIKAN Oil DROPS"

    Science.gov (United States)

    Chiao, Raymond Y.

    Pairs of Planck-mass drops of superfluid helium coated by electrons (i.e. "Millikan oil drops"), when levitated in a superconducting magnetic trap, can be efficient quantum transducers between electromagnetic (EM) and gravitational (GR) radiation. This leads to the possibility of a Hertz-like experiment, in which EM waves are converted at the source into GR waves, and then back-converted at the receiver from GR waves into EM waves. Detection of the gravitational-wave analog of the cosmic microwave background using these drops can discriminate between various theories of the early Universe.

  11. Nucleosynthesis constraints on active-sterile neutrino conversions in the early universe with random magnetic field

    CERN Document Server

    Semikoz, V B

    1994-01-01

    We consider active-sterile neutrino conversions in the early universe hot plasma in the presence of a random magnetic field generated at the electroweak phase transition. Within a random field domain the magnetization asymmetry of the lepton antilepton plasma produced by a uniform constant magnetic field is huge in contrast to their small density asymmetry, leading to a drastic change in the active-sterile conversion rates. Assuming that the random field provides the seed for the galactic field one can estimate the restrictions from primordial nucleosynthesis. Requiring that the extra sterile \

  12. A cross-linguistic study of early word meaning: universal ontology and linguistic influence.

    Science.gov (United States)

    Imai, M; Gentner, D

    1997-02-01

    This research concerns how children learn the distinction between substance names and object names. Quine (1969) proposed that children learn the distinction through learning the syntactic distinctions inherent in count/mass grammar. However, Soja et al. (1991) found that English-speaking 2-year-olds, who did not seem to have acquired count/mass grammar, distinguished objects from substances in a word extension task, suggesting a pre-linguistic ontological distinction. To test whether the distinction between object names and substance names is conceptually or linguistically driven, we repeated Soja et al.'s study with English- and Japanese-speaking 2-, 2.5-, and 4-year-olds and adults. Japanese does not make a count-mass grammatical distinction: all inanimate nouns are treated alike. Thus if young Japanese children made the object-substance distinction in word meaning, this would support the early ontology position over the linguistic influence position. We used three types of standards: substances (e.g., sand in an S-shape), simple objects (e.g., a kidney-shaped piece of paraffin) and complex objects (e.g., a wood whisk). The subjects learned novel nouns in neutral syntax denoting each standard entity. They were then asked which of the two alternatives--one matching in shape but not material and the other matching in material but not shape--would also be named by the same label. The results suggest the universal use of ontological knowledge in early word learning. Children in both languages showed differentiation between (complex) objects and substances as early as 2 years of age. However, there were also early cross-linguistic differences. American and Japanese children generalized the simple object instances and the substance instances differently. We speculate that children universally make a distinction between individuals and non-individuals in word learning but that the nature of the categories and the boundary between them is influenced by language.

  13. Early season mesopelagic carbon remineralization and transfer efficiency in the naturally iron-fertilized Kerguelen area

    Science.gov (United States)

    Jacquet, S. H. M.; Dehairs, F.; Cavagna, A. J.; Planchon, F.; Monin, L.; André, L.; Closset, I.; Cardinal, D.

    2014-06-01

    We report on the zonal variability of mesopelagic particulate organic carbon) remineralization and deep carbon transfer potential during the Kerguelen Ocean and Plateau compared Study 2 expedition (KEOPS 2; October-November 2011) in an area of the Polar Front supporting recurrent massive blooms from natural Fe fertilization. Mesopelagic carbon remineralization was assessed using the excess, non-lithogenic particulate barium (Baxs) inventories in mesopelagic waters and compared with surface primary and export productions. Results for this early season study are compared with results obtained earlier (2005; KEOPS 1) for the same area during summer. For the Kerguelen plateau (A3 site) we observe a similar functioning of the mesopelagic ecosystem during both seasons (spring and summer), with less that 30% of carbon exported from the upper 150 m being remineralized in the mesopelagic column (150-400 m). For deeper stations (> 2000 m) located on the margin, inside a Polar Front meander, as well as in the vicinity of the Polar Front, east of Kerguelen, remineralization in the upper 400 m in general represents > 30% of carbon export, but when considering the upper 800 m, in some cases, the entire flux of exported carbon is remineralized. It appears that above the plateau (A3 site) mesopelagic remineralization is not a major barrier to the transfer of organic matter to the sea-floor (close to 500 m). There the efficiency of carbon sequestration into the bottom waters (> 400 m) reached up to 87% of the carbon exported from the upper 150 m. In contrast, at the deeper locations mesopelagic remineralization clearly limits the sequestration of carbon to depths > 400 m. For sites at the margin of the plateau (station E-4W) and the Polar front (station F-L), mesopelagic remineralization even exceeds upper 150 m export, resulting in a null sequestration efficiency to depths > 800 m. In the Polar Front meander, where successive stations form a time series, the capacity of the

  14. Early season mesopelagic carbon remineralization and transfer efficiency in the naturally iron-fertilized Kerguelen area

    Directory of Open Access Journals (Sweden)

    S. H. M. Jacquet

    2014-06-01

    Full Text Available We report on the zonal variability of mesopelagic particulate organic carbon remineralization and deep carbon transfer potential during the Kerguelen Ocean and Plateau compared Study 2 expedition (KEOPS 2; October–November 2011 in an area of the Polar Front supporting recurrent massive blooms from natural Fe fertilization. Mesopelagic carbon remineralization was assessed using the excess, non-lithogenic particulate barium (Baxs inventories in mesopelagic waters and compared with surface primary and export productions. Results for this early season study are compared with results obtained earlier (2005; KEOPS 1 for the same area during summer. For the Kerguelen plateau (A3 site we observe a similar functioning of the mesopelagic ecosystem during both seasons (spring and summer, with less that 30% of carbon exported from the upper 150 m being remineralized in the mesopelagic column (150–400 m. For deeper stations (> 2000 m located on the margin, inside a Polar Front meander, as well as in the vicinity of the Polar Front, east of Kerguelen, remineralization in the upper 400 m in general represents > 30% of carbon export, but when considering the upper 800 m, in some cases, the entire flux of exported carbon is remineralized. It appears that above the plateau (A3 site mesopelagic remineralization is not a major barrier to the transfer of organic matter to the sea-floor (close to 500 m. There the efficiency of carbon sequestration into the bottom waters (> 400 m reached up to 87% of the carbon exported from the upper 150 m. In contrast, at the deeper locations mesopelagic remineralization clearly limits the sequestration of carbon to depths > 400 m. For sites at the margin of the plateau (station E-4W and the Polar front (station F-L, mesopelagic remineralization even exceeds upper 150 m export, resulting in a null sequestration efficiency to depths > 800 m. In the Polar Front meander, where successive stations form a time series, the capacity of

  15. Carbon Isotope Evolution of Early Proterozoic Dolomites of Wutai Mountain Area,North China

    Institute of Scientific and Technical Information of China (English)

    钟华; 马永生; 霍卫国; 姚御元

    1994-01-01

    Carbon isotope of the early Proterozoic carbonates from the Hutuo Group of the type sec-tion in Wutai Mountain area,Shanxi Province,North China,is reported.Isotopic analyses have been madefor 484 samples of dolomites.The carbon isotope results show:(i)δ13C values distinctly change with the ge-ological time,but are relatively stable in certain horizon;(ii)like that at the Cretaceous/Tertiary and Permi-an/Triassic boundaries,δ13C values also show abrupt variation across the boundaries between the JianancunFormation and the Daguandong Formation and between the Daguandong Formation and the Huaiyincun For-mation.

  16. Hot Oxygen and Carbon Escape from the Early Atmosphere of Mars

    Science.gov (United States)

    Amerstorfer, U.; Gröller, H.; Lichtenegger, H.; Lammer, H.; Tian, F.

    2015-12-01

    Nowadays, the atmosphere of Mars is commonly assumed to be much different than in the early times of its evolution. Especially, the escape of water and carbon dioxide is thought to have formed its shape during millions of years. Also the Sun emitted a higher EUV flux in former times, influencing the particle environment around Mars.We study the escape of oxygen and carbon from the early Martian atmosphere for different EUV fluxes with a Monte-Carlo model. We consider different possible sources of hot oxygen and carbon atoms in the thermosphere, e.g. dissociative recombination of O2+ , CO+ and CO2+ , photodissociation of O2 and CO, and other reactions like charge transfer. From the calculated production rate profiles we can get insights into the importance of the different source reactions. The resulting energy distribution functions at the exobase level are used to study the exospheric densities and the escape of hot oxygen and carbon. We discuss the escape rates of those atoms and the importance of different source processes compared to the present situation at Mars.This work receives funding from the Austrian Science Fund (FWF): P 24247.

  17. Possible Decoupling of the Geochemical Cycles of Sulfur and Carbon During the Early Cretaceous (Hauterivian)

    Science.gov (United States)

    Kristall, B.; Hurtgen, M. T.; Sageman, B. B.

    2013-12-01

    During the past decade there has been significant focus on understanding the global sulfur cycle during the Mid- to Late-Cretaceous. The occurrence of several oceanic anoxic events (OAEs) during this time period and the relationships among the sulfur, carbon, and oxygen cycles controlling the redox state of the ocean have been motivating factors in this research. These efforts have centered on identifying what impact, if any, massive volcanism and evaporite deposition associated with opening of the South Atlantic had on the sulfate content of the ocean and what role these events may have played in triggering OAEs. However, relatively little work has been done to characterize the sulfur cycle during the Early Cretaceous. In the present study, we have analyzed the sulfur isotope composition of carbonate-associated sulfate (CAS) from Hauterivian-aged samples (Resolution Guyot ODP Hole 866A). We found a previously unrecognized ~4‰ positive sulfur isotope excursion in sulfate sulfur. This well structured, excursion spans approximately 15-20 m of core and is estimated to be less than 300-500 kyr. Corresponding carbonate carbon isotope analyses do not show a comparable, well-structured excursion. During this event δ13C values vary only by 0.25-0.5‰. The rapid shift and recovery in δ34Ssulfate suggests either that this event was regional or that the Early Cretaceous oceans contained low sulfate levels (factors necessary to produce the observed S isotope shift without a corresponding change in C isotope composition.

  18. A universal airborne LiDAR approach for tropical forest carbon mapping.

    Science.gov (United States)

    Asner, Gregory P; Mascaro, Joseph; Muller-Landau, Helene C; Vieilledent, Ghislain; Vaudry, Romuald; Rasamoelina, Maminiaina; Hall, Jefferson S; van Breugel, Michiel

    2012-04-01

    Airborne light detection and ranging (LiDAR) is fast turning the corner from demonstration technology to a key tool for assessing carbon stocks in tropical forests. With its ability to penetrate tropical forest canopies and detect three-dimensional forest structure, LiDAR may prove to be a major component of international strategies to measure and account for carbon emissions from and uptake by tropical forests. To date, however, basic ecological information such as height-diameter allometry and stand-level wood density have not been mechanistically incorporated into methods for mapping forest carbon at regional and global scales. A better incorporation of these structural patterns in forests may reduce the considerable time needed to calibrate airborne data with ground-based forest inventory plots, which presently necessitate exhaustive measurements of tree diameters and heights, as well as tree identifications for wood density estimation. Here, we develop a new approach that can facilitate rapid LiDAR calibration with minimal field data. Throughout four tropical regions (Panama, Peru, Madagascar, and Hawaii), we were able to predict aboveground carbon density estimated in field inventory plots using a single universal LiDAR model (r ( 2 ) = 0.80, RMSE = 27.6 Mg C ha(-1)). This model is comparable in predictive power to locally calibrated models, but relies on limited inputs of basal area and wood density information for a given region, rather than on traditional plot inventories. With this approach, we propose to radically decrease the time required to calibrate airborne LiDAR data and thus increase the output of high-resolution carbon maps, supporting tropical forest conservation and climate mitigation policy.

  19. From Universalism to Selectivity? The Background, Discourses and Ideas of Recent Early Childhood Education and Care Reforms in Finland

    Science.gov (United States)

    Lundkvist, Marina; Nyby, Josefine; Autto, Janne; Nygård, Mikael

    2017-01-01

    Universal public childcare for children under seven has been central in Finland since the mid-1990s, capacitating both gender equality and children's human capital and wellbeing. In 2015, as a further step in the development of this system, early learning and childhood pedagogy was strengthened through the early childhood education and care (ECEC)…

  20. Effect of the Lee-Wick partners in the evolution of the early universe

    CERN Document Server

    Bhattacharya, Kaushik

    2012-01-01

    Recently some work has been done on Lee-Wick standard model where the authors tried to tackle the hierarchy problem by using higher derivative field theory. All those theories require unusual Lee-Wick partners to the Standard model particles where these unusual fields appear with negative signs in the Lagrangian. The thermodynamics of such unusual Lee-Wick particles has also been studied. In the present article the thermodynamic results of the Lee-Wick partner infested universe have been applied in a model where there is one Lee-Wick partner to each of the standard model particle. In this model one can analytically calculate the time-temperature relation in the very early radiation dominated universe which shows interesting new physics. The article also tries to point out how a Lee-Wick particle dominated early cosmology transforms into the standard cosmological model. Based on the results of the previous analysis a brief discussion on the more realistic model, which can accommodate two Lee-Wick parters for e...

  1. Preheating of the early universe by radiation from high-mass X-ray binaries

    Science.gov (United States)

    Sazonov, S. Yu.; Khabibullin, I. I.

    2017-04-01

    Using a reliablymeasured intrinsic (i.e., corrected for absorption effects) present-day luminosity function of high-mass X-ray binaries (HMXBs) in the 0.25-2 keV energy band per unit star formation rate, we estimate the preheating of the early Universe by soft X-rays from such systems. We find that X-ray irradiation, mainly executed by ultraluminous and supersoft ultraluminous X-ray sources with luminosity L X > 1039 erg s-1, could significantly heat ( T > T CMB, where T CMB is the temperature of the cosmic microwave background) the intergalactic medium by z 10 if the specific X-ray emissivity of the young stellar population in the early Universe was an order of magnitude higher than at the present epoch (which is possible due to the low metallicity of the first galaxies) and the soft X-ray emission from HMXBs did not suffer strong absorption within their galaxies. This makes it possible to observe the 21 cm line of neutral hydrogen in emission from redshifts z < 10.

  2. The significance of an Early Jurassic (Toarcian) carbon-isotope excursion in Haida Gwaii (Queen Charlotte Islands), British Columbia, Canada

    Science.gov (United States)

    Caruthers, Andrew H.; Gröcke, Darren R.; Smith, Paul L.

    2011-07-01

    During the Early Toarcian there was a significant disruption in the short-term active carbon reservoir as revealed by carbon-isotope records, which show a broad positive shift that is interrupted by a large 5-7‰ negative excursion (δ 13C org). Carbon-isotope excursion co-occurs with the deposition of organic-rich shales in many areas. This perturbation in carbon isotopes is thought to be indicative of severe climate change and marine anoxia. The two leading hypotheses as to the cause of this event invoke either global or regional controls. Here we present carbon-isotope data from Haida Gwaii, British Columbia, Canada showing a significant perturbation within a temporally constrained Early Toarcian succession that was deposited in the northeastern paleo-Pacific Ocean. These data reinforce the concept that the short-term active carbon reservoir was affected globally, and assist with the correlation of ammonite zonal schemes between western North America and Europe. The δ 13C org data show a broad positive shift that is interrupted by a sharp and pronounced negative excursion of 7‰ (8.5‰ in δ 13C wood) in the Early Toarcian Kanense Zone. This negative excursion also coincides with increasing total organic carbon (TOC) from ~ 0.4% to ~ 1.2%. These data suggest that the Early Toarcian carbon-isotope perturbation was indeed global and imprinted itself on all active global reservoirs of the exchangeable carbon cycle (deep marine, shallow marine, atmospheric).

  3. Diet and mobility in Early Medieval Bavaria: a study of carbon and nitrogen stable isotopes.

    Science.gov (United States)

    Hakenbeck, Susanne; McManus, Ellen; Geisler, Hans; Grupe, Gisela; O'Connell, Tamsin

    2010-10-01

    This study investigates patterns of mobility in Early Medieval Bavaria through a combined study of diet and associated burial practice. Carbon and nitrogen isotope ratios were analyzed in human bone samples from the Late Roman cemetery of Klettham and from the Early Medieval cemeteries of Altenerding and Straubing-Bajuwarenstrasse. For dietary comparison, samples of faunal bone from one Late Roman and three Early Medieval settlement sites were also analyzed. The results indicate that the average diet was in keeping with a landlocked environment and fairly limited availability of freshwater or marine resources. The diet appears not to have changed significantly from the Late Roman to the Early Medieval period. However, in the population of Altenerding, there were significant differences in the diet of men and women, supporting a hypothesis of greater mobility among women. Furthermore, the isotopic evidence from dietary outliers is supported by "foreign" grave goods and practices, such as artificial skull modification. These results reveal the potential of carbon and nitrogen isotope analysis for questions regarding migration and mobility.

  4. From simple to complex prebiotic chemistry in a carbon-rich universe

    Science.gov (United States)

    Lage, C.; Janot-Pacheco, E.; Domiciano de Souza, A.; Suárez, O.; Bendjoya, P.; Gadotti, D. A.

    2012-09-01

    It is well known that the main components of important biomolecules are quite common not only in the Solar System, but also in other planetary systems and in the Galactic ISM. The ubiquitous presence of C in the Universe and the unique carbon chemical properties and carbon bonding thermodynamics supports the spontaneous self-replication of monomers into larger polymers, yielding the formation of large molecules. The detection of an ever increasing number of organic molecules in the interstellar medium (ISM) by radio-telescopes and chemical analysis of meteorites boosted astrochemical theories on radiation-induced chemistry, supported by laboratory experiments. In this scenario of exogenous origin of carbon compounds, polyaromatic hydrocarbons (PAHs) may represent a resilient way of accumulating carbon as a robust cosmic reservoir. Consisting of a family of compounds with fused aromatic rings, the abundances of its larger members (50-100 carbon atoms) were estimated to be on top scores just after H2 and CO. PAHs have been detected in the ISM, in star-forming regions, ~14% of low-mass premainsequence stars, and, remarkably, in some 54% of intermediate mass stars. They have also been detected by SPITZER in distant galaxies up to z = 3. PAHs were promptly photolysed into a family of radicals if exposed to UV and oxygen-bearing molecules in laboratory. The presence of oxygenbearing molecules was shown in the laboratory to bring aromatic rings into an unstable chemistry leading to the production of e.g. alcohols, ketones and ether radicals. It has already been observed that carbon-and oxygen-rich stellar envelopes give rise to richer carbon chemistry. It appears very tempting to think that key prebiotic fragments should appear along planetary formation as C-O reaction byproducts such as methanol (CH3OH), formaldehyde (H2CO) and also simpler hydrocarbons as methyl acetylene (CH3CCH). Under an Astrobiology perspective it is plausible to map PAHs and oxygen compounds

  5. Encouraging entrepreneurship in university labs: Research activities, research outputs, and early doctorate careers

    Science.gov (United States)

    2017-01-01

    This paper investigates how the encouragement of entrepreneurship within university research labs relates with research activities, research outputs, and early doctorate careers. Utilizing a panel survey of 6,840 science & engineering doctoral students at 39 R1 research universities, this study shows that entrepreneurship is widely encouraged across university research labs, ranging from 54% in biomedical engineering to 18% in particle physics, while only a small share of labs openly discourage entrepreneurship, from approximately 3% in engineering to approximately 12% in the life sciences. Within fields, there is no difference between labs that encourage entrepreneurship and those that do not with respect to basic research activity and the number of publications. At the same time, labs that encourage entrepreneurship are significantly more likely to report invention disclosures, particularly in engineering where such labs are 41% more likely to disclose inventions. With respect to career pathways, PhDs students in labs that encourage entrepreneurship do not differ from other PhDs in their interest in academic careers, but they are 87% more likely to be interested in careers in entrepreneurship and 44% more likely to work in a startup after graduation. These results persist even when accounting for individuals’ pre-PhD interest in entrepreneurship and the encouragement of other non-academic industry careers. PMID:28178270

  6. Primordial black hole formation in the early universe: critical behaviour and self-similarity

    CERN Document Server

    Musco, Ilia

    2012-01-01

    Following on after three previous papers discussing the formation of primordial black holes during the radiation-dominated era of the early universe, we present here a further investigation of the critical nature of the collapse. In particular, we focus on the long-lived intermediate state, which appears in collapses of perturbations close to the critical limit, and examine the extent to which this follows a similarity solution, as seen for critical collapse under more idealized circumstances (rather than within the context of an expanding universe, as studied here). We find that a similarity solution is indeed realised, to good approximation, for a region contained within the past light-cone of the forming black hole (and eventual singularity). The self-similarity is not exact, however, and this is explained by the presence within the light-cone of some outer matter still coupled to the expanding universe, which does not participate in the self-similarity. Our main interest, from a cosmological point of view...

  7. Encouraging entrepreneurship in university labs: Research activities, research outputs, and early doctorate careers.

    Science.gov (United States)

    Roach, Michael

    2017-01-01

    This paper investigates how the encouragement of entrepreneurship within university research labs relates with research activities, research outputs, and early doctorate careers. Utilizing a panel survey of 6,840 science & engineering doctoral students at 39 R1 research universities, this study shows that entrepreneurship is widely encouraged across university research labs, ranging from 54% in biomedical engineering to 18% in particle physics, while only a small share of labs openly discourage entrepreneurship, from approximately 3% in engineering to approximately 12% in the life sciences. Within fields, there is no difference between labs that encourage entrepreneurship and those that do not with respect to basic research activity and the number of publications. At the same time, labs that encourage entrepreneurship are significantly more likely to report invention disclosures, particularly in engineering where such labs are 41% more likely to disclose inventions. With respect to career pathways, PhDs students in labs that encourage entrepreneurship do not differ from other PhDs in their interest in academic careers, but they are 87% more likely to be interested in careers in entrepreneurship and 44% more likely to work in a startup after graduation. These results persist even when accounting for individuals' pre-PhD interest in entrepreneurship and the encouragement of other non-academic industry careers.

  8. Tom Kibble and the early universe as the ultimate high energy experiment

    Science.gov (United States)

    Turok, Neil

    2014-02-01

    Tom Kibble pioneered the idea that there were one or more symmetry breaking phase transitions in the very early universe, at which defects like monopoles, strings and domain walls would have formed. In the context of grand unified theories, or their extensions, this idea remains compelling: observing these defects would be one of the very few ways of directly confirming the theories. In contrast, inflationary theory invoked a strongly supercooled transition driving a period of exponential expansion which would sweep all such defects away. If inflation terminated slowly, quantum vacuum fluctuations would be amplified and stretched to cosmological scales, forming density variations of just the character required to explain the formation of galaxies. The ensuing paradigm has dominated cosmology for the last three decades. However, basic problems in the scenario remain unresolved. Extreme tuning both of the initial conditions and of the physical laws are required. There are many different versions, each with slightly different predictions. Finally, inflation brought with it the theory of a "multiverse" — a universe containing infinite number of different, infinite, universes — while providing no "measure" or means of calculating the probability of observing any one of them. I will discuss an alternative to inflation, in which the big bang was a bounce from a previous contracting epoch. The discovery of the Higgs boson at the LHC has provided new evidence for such a picture by showing that, within the minimal standard model, our current vacuum is metastable. This opens the door to a cyclic universe scenario in which the electroweak Higgs plays a central role.

  9. Building the Next Generation of Earth Scientists: the Deep Carbon Observatory Early Career Scientist Workshops

    Science.gov (United States)

    Pratt, K.; Fellowes, J.; Giovannelli, D.; Stagno, V.

    2016-12-01

    Building a network of collaborators and colleagues is a key professional development activity for early career scientists (ECS) dealing with a challenging job market. At large conferences, young scientists often focus on interacting with senior researchers, competing for a small number of positions in leading laboratories. However, building a strong, international network amongst their peers in related disciplines is often as valuable in the long run. The Deep Carbon Observatory (DCO) began funding a series of workshops in 2014 designed to connect early career researchers within its extensive network of multidisciplinary scientists. The workshops, by design, are by and for early career scientists, thus removing any element of competition and focusing on peer-to-peer networking, collaboration, and creativity. The successful workshops, organized by committees of early career deep carbon scientists, have nucleated a lively community of like-minded individuals from around the world. Indeed, the organizers themselves often benefit greatly from the leadership experience of pulling together an international workshop on budget and on deadline. We have found that a combination of presentations from all participants in classroom sessions, professional development training such as communication and data management, and field-based relationship building and networking is a recipe for success. Small groups within the DCO ECS network have formed; publishing papers together, forging new research directions, and planning novel and ambitious field campaigns. Many DCO ECS also have come together to convene sessions at major international conferences, including the AGU Fall Meeting. Most of all, there is a broad sense of camaraderie and accessibility within the DCO ECS Community, providing the foundation for a career in the new, international, and interdisciplinary field of deep carbon science.

  10. Men in Early Childhood: A Moral Panic? A research report from a UK University

    Directory of Open Access Journals (Sweden)

    Cronin Mark

    2014-07-01

    Full Text Available Significant changes in the role fathers play in their children’s care alongside the increased interest shown by teenage boys in working with young children has so far resulted in no noticeable increase in the numbers of men working in Early Childhood in the UK. Previous research has identified how the gendered nature of this workforce presents significant barriers to men’s involvement combined with an increasingly dogmatic media discourse which represents men solely as a threat to young children. The research reported in this paper explored the experiences of a group of undergraduate male students in their pursuit of a career working with young children and to what degree the dynamics of being othered had impacted them. It also sought to consider the rhetoric and reality of recent UK government attempts to address the imbalance in the Early Childhood workforce. Thirteen male students from two undergraduate programmes at a UK University were interviewed for this study. The research data identified a number of risk factors which present barriers to men’s involvement in Early Childhood such as gender stereotyping, marginalisation or ‘othering’ of men and negative media discourses. It also identified potential protective factors which enable men’s involvement such as supportive family and friends, male role-models and a sense of social responsibility. Broader reflections also identified the significant difference between the UK government rhetoric in support of increasing men’s participation in Early Childhood and the reality of the active indifference shown to challenging the barriers to participation driven by political motives which has effectively generated a new ‘moral panic’ around men working with young children.

  11. New insights into the early stages of silica-controlled barium carbonate crystallisation

    Science.gov (United States)

    Eiblmeier, Josef; Schürmann, Ulrich; Kienle, Lorenz; Gebauer, Denis; Kunz, Werner; Kellermeier, Matthias

    2014-11-01

    Recent work has demonstrated that the dynamic interplay between silica and carbonate during co-precipitation can result in the self-assembly of unusual, highly complex crystal architectures with morphologies and textures resembling those typically displayed by biogenic minerals. These so-called biomorphs were shown to be composed of uniform elongated carbonate nanoparticles that are arranged according to a specific order over mesoscopic scales. In the present study, we have investigated the circumstances leading to the continuous formation and stabilisation of such well-defined nanometric building units in these inorganic systems. For this purpose, in situ potentiometric titration measurements were carried out in order to monitor and quantify the influence of silica on both the nucleation and early growth stages of barium carbonate crystallisation in alkaline media at constant pH. Complementarily, the nature and composition of particles occurring at different times in samples under various conditions were characterised ex situ by means of high-resolution electron microscopy and elemental analysis. The collected data clearly evidence that added silica affects carbonate crystallisation from the very beginning (i.e. already prior to, during, and shortly after nucleation), eventually arresting growth on the nanoscale by cementation of BaCO3 particles within a siliceous matrix. Our findings thus shed light on the fundamental processes driving bottom-up self-organisation in silica-carbonate materials and, for the first time, provide direct experimental proof that silicate species are responsible for the miniaturisation of carbonate crystals during growth of biomorphs, hence confirming previously discussed theoretical models for their formation mechanism.Recent work has demonstrated that the dynamic interplay between silica and carbonate during co-precipitation can result in the self-assembly of unusual, highly complex crystal architectures with morphologies and textures

  12. Diluting the inflationary axion fluctuation by a stronger QCD in the early Universe

    CERN Document Server

    Choi, Kiwoon; Im, Sang Hui; Jeong, Kwang Sik

    2015-01-01

    We propose a new mechanism to suppress the axion isocurvature perturbation, while producing the right amount of axion dark matter, within the framework of supersymmetric axion models with the axion scale induced by supersymmetry breaking. The mechanism involves an intermediate phase transition to generate the Higgs \\mu-parameter, before which the weak scale is comparable to the axion scale and the resulting stronger QCD yields an axion mass heavier than the Hubble scale over a certain period. Combined with that the Hubble-induced axion scale during the primordial inflation is well above the intermediate axion scale at present, the stronger QCD in the early Universe suppresses the axion fluctuation to be small enough even when the inflationary Hubble scale saturates the current upper bound, while generating an axion misalignment angle of order unity.

  13. Probing the Early Universe with the CMB Scalar, Vector and Tensor Bispectrum

    CERN Document Server

    Shiraishi, Maresuke

    2012-01-01

    Although cosmological observations suggest that the fluctuations of seed fields are almost Gaussian, the possibility of a small deviation of their fields from Gaussianity is widely discussed. Theoretically, there exist numerous inflationary scenarios which predict large and characteristic non-Gaussianities in the primordial perturbations. These model-dependent non-Gaussianities act as sources of the Cosmic Microwave Background (CMB) bispectrum; therefore, the analysis of the CMB bispectrum is very important and attractive in order to clarify the nature of the early Universe. Currently, the impacts of the primordial non-Gaussianities in the scalar perturbations, where the rotational and parity invariances are kept, on the CMB bispectrum have been well-studied. However, for a complex treatment, the CMB bispectra generated from the non-Gaussianities, which originate from the vector- and tensor-mode perturbations and include the violation of the rotational or parity invariance, have never been considered in spite...

  14. Back to the early Universe by a Monge-Ampere-Kantorovich mass transportation method

    CERN Document Server

    Frisch, U; Mohayaee, R; Sobolevski, A; Frisch, Uriel; Matarrese, Sabino; Mohayaee, Roya; Sobolevski, Andrei

    2002-01-01

    Reconstructing the minute density fluctuations in the early Universe that evolved into a highly clumpy matter distribution, as revealed by the present distribution of luminous matter, constitutes a major challenge of modern cosmology. A number of techniques have been devised in recent years which attempt to achieve this aim by using galaxy positions alone [8 refs.]. However, without knowledge of their velocities, this problem is not well-posed and its solution suffers frequently from lack of uniqueness. Here we make the hypothesis that the map from initial to present locations of mass elements is irrotational. Using recent mathematical work [Brenier], we then relate reconstruction to ``mass transportation'', a well-posed optimisation problem in engineering introduced by Monge in 1781. We propose a new powerful algorithm for unique reconstruction which, when tested against N-body simulations, gives excellent reconstruction down to scales of a few comoving megaparsecs and demonstrates the validity of our hypoth...

  15. Diluting the inflationary axion fluctuation by a stronger QCD in the early Universe

    Directory of Open Access Journals (Sweden)

    Kiwoon Choi

    2015-11-01

    Full Text Available We propose a new mechanism to suppress the axion isocurvature perturbation, while producing the right amount of axion dark matter, within the framework of supersymmetric axion models with the axion scale induced by supersymmetry breaking. The mechanism involves an intermediate phase transition to generate the Higgs μ-parameter, before which the weak scale is comparable to the axion scale and the resulting stronger QCD yields an axion mass heavier than the Hubble scale over a certain period. Combined with that the Hubble-induced axion scale during the primordial inflation is well above the intermediate axion scale at present, the stronger QCD in the early Universe suppresses the axion fluctuation to be small enough even when the inflationary Hubble scale saturates the current upper bound, while generating an axion misalignment angle of order unity.

  16. Active-sterile neutrino oscillations in the early universe with dynamical neutrino asymmetries

    Energy Technology Data Exchange (ETDEWEB)

    Saviano, Ninetta

    2013-04-15

    In the last recent years different anomalies observed in short-baseline neutrino oscillation experiments seem to point towards the existence of light sterile neutrinos. These sterile neutrinos can also be produced in the early universe by oscillations of the active neutrinos and can affect different cosmological observables. In order to quantify the abundance of sterile neutrinos, we perform a detailed study of the flavor evolution in (3+1) and (2+1) oscillation schemes, in presence of dynamical primordial neutrino asymmetries L. We find that for |L|≲10{sup −4}eV sterile neutrinos would be completely thermalized creating a tension with the cosmological data. An asymmetry of |L|≳10{sup −3} is then required in order to suppress the sterile production and to reconcile them with cosmology.

  17. Active-sterile neutrino oscillations in the early Universe with full collision terms

    Science.gov (United States)

    Hannestad, Steen; Sloth Hansen, Rasmus; Tram, Thomas; Wong, Yvonne Y. Y.

    2015-08-01

    Sterile neutrinos are thermalised in the early Universe via oscillations with the active neutrinos for certain mixing parameters. The most detailed calculation of this thermalisation process involves the solution of the momentum-dependent quantum kinetic equations, which track the evolution of the neutrino phase space distributions. Until now the collision terms in the quantum kinetic equations have always been approximated using equilibrium distributions, but this approximation has never been checked numerically. In this work we revisit the sterile neutrino thermalisation calculation using the full collision term, and compare the results with various existing approximations in the literature. We find a better agreement than would naively be expected, but also identify some issues with these approximations that have not been appreciated previously. These include an unphysical production of neutrinos via scattering and the importance of redistributing momentum through scattering, as well as details of Pauli blocking. Finally, we devise a new approximation scheme, which improves upon some of the shortcomings of previous schemes.

  18. An inflationary scenario taking into account of possible dark energy effects in the early universe

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Zhe; Li, Ming-Hua [Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China); Li, Xin; Wang, Sai [Chinese Academy of Sciences, Theoretical Physics Center for Science Facilities, Beijing (China)

    2012-03-15

    We investigate the possible effect of cosmological-constant type dark energy during the inflation period of the early universe. This is accommodated by a new dispersion relation in de Sitter space. The modified inflation model of a minimally coupled scalar field is still able to yield an observation-compatible scale-invariant primordial spectrum, simultaneously having the potential to generate a spectrum with lower power at large scales. A qualitative match to the WMAP 7-year data is presented. We obtain an {omega}{sub {lambda}} of the same order of that in the {lambda}-CDM model. Possible relations between the de Sitter scenario and Doubly Special Relativity (DSR) are also discussed. (orig.)

  19. Diluting the inflationary axion fluctuation by a stronger QCD in the early Universe

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kiwoon, E-mail: kchoi@ibs.re.kr [Center for Theoretical Physics of the Universe, IBS, Daejeon 305-811 (Korea, Republic of); Chun, Eung Jin, E-mail: ejchun@kias.re.kr [Korea Institute for Advanced Study, Seoul 130-722 (Korea, Republic of); Im, Sang Hui, E-mail: shim@ibs.re.kr [Center for Theoretical Physics of the Universe, IBS, Daejeon 305-811 (Korea, Republic of); Jeong, Kwang Sik, E-mail: ksjeong@pusan.ac.kr [Department of Physics, Pusan National University, Busan, 609-735 (Korea, Republic of)

    2015-11-12

    We propose a new mechanism to suppress the axion isocurvature perturbation, while producing the right amount of axion dark matter, within the framework of supersymmetric axion models with the axion scale induced by supersymmetry breaking. The mechanism involves an intermediate phase transition to generate the Higgs μ-parameter, before which the weak scale is comparable to the axion scale and the resulting stronger QCD yields an axion mass heavier than the Hubble scale over a certain period. Combined with that the Hubble-induced axion scale during the primordial inflation is well above the intermediate axion scale at present, the stronger QCD in the early Universe suppresses the axion fluctuation to be small enough even when the inflationary Hubble scale saturates the current upper bound, while generating an axion misalignment angle of order unity.

  20. Spontaneous B-L Breaking as the Origin of the Hot Early Universe

    CERN Document Server

    Buchmüller, Wilfried; Schmitz, Kai

    2012-01-01

    The decay of a false vacuum of unbroken B-L symmetry is an intriguing and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase yields hybrid inflation, ending in tachyonic preheating. The dynamics of the B-L breaking Higgs field and thermal processes produce an abundance of heavy neutrinos whose decays generate entropy, baryon asymmetry and gravitino dark matter. We study the phase transition for the full supersymmetric Abelian Higgs model. For the subsequent reheating process we give a detailed time-resolved description of all particle abundances. The competition of cosmic expansion and entropy production leads to an intermediate period of constant 'reheating' temperature, during which baryon asymmetry and dark matter are produced. Consistency of hybrid inflation, leptogenesis and gravitino dark matter implies relations between neutrino parameters and superparticle masses, in particular a lower bound on the gr...

  1. On the origin of Hawking mini black-holes and the cold early universe

    Science.gov (United States)

    Canuto, V.

    1978-01-01

    A simple argument is outlined leading to the result that the mass of mini black holes exploding today is 10 to the 15th power g. A mathematical model is discussed which indicates that the equation of state is greatly softened in the high-density regime and a phase transition may exist, such that any length (particularly very small sizes) will grow with time irrespective of its relation to the size of the particle horizon. It is shown that the effect of spin-2 mesons with respect to the equation of state is to soften the pressure and make it negative. An analytical expression is given for the probability that any particular region in a hot early universe will evolve into a black hole.

  2. A Tale of Two Timescales: Mixing, Mass Generation, and Phase Transitions in the Early Universe

    CERN Document Server

    Dienes, Keith R; Thomas, Brooks

    2015-01-01

    Light scalar fields such as axions and string moduli can play an important role in early-universe cosmology. However, many factors can significantly impact their late-time cosmological abundances. For example, in cases where the potentials for these fields are generated dynamically --- such as during cosmological mass-generating phase transitions --- the duration of the time interval required for these potentials to fully develop can have significant repercussions. Likewise, in scenarios with multiple scalars, mixing amongst the fields can also give rise to an effective timescale that modifies the resulting late-time abundances. Previous studies have focused on the effects of either the first or the second timescale in isolation. In this paper, by contrast, we examine the new features that arise from the interplay between these two timescales when both mixing and time-dependent phase transitions are introduced together. First, we find that the effects of these timescales can conspire to alter not only the tot...

  3. Early afterglow, magnetized central engine, and a quasi-universal jet configuration for long GRBs

    CERN Document Server

    Zhang, B; Kobayashi, S; Lloyd-Ronning, N M; Mészáros, P; Dai, Xinyu; Kobayashi, Shiho; Lloyd-Ronning, Nicole M.; Meszaros, Peter; Zhang, Bing

    2003-01-01

    Two separate topics are discussed. (1) We describe the classifications of the long GRB early afterglow lightcurves within the framework of the fireball shock model, focusing on the interplay between the reverse and forward shock emission components. We will also provide evidence that the central engine of at least two bursts are entrained with strong magnetic fields, and discuss the implications of this result for our understanding of the GRB phenomenon; (2) We argue that the current gamma-ray burst (GRB) and X-ray flash (XRF) data are consistent with a picture that all GRB-XRF jets are structured and quasi-universal, with a typical Gaussian-like jet structure.

  4. Active-sterile neutrino oscillations in the early Universe with full collision terms

    Energy Technology Data Exchange (ETDEWEB)

    Hannestad, Steen [Department of Physics and Astronomy,Aarhus University, 8000 Aarhus C (Denmark); Aarhus Institute of Advanced Studies,Aarhus University, 8000 Aarhus C (Denmark); Hansen, Rasmus Sloth [Department of Physics and Astronomy,Aarhus University, 8000 Aarhus C (Denmark); School of Physics, The University of New South Wales,Sydney NSW 2052 (Australia); Tram, Thomas [Institute of Cosmology and Gravitation, University of Portsmouth,Portsmouth PO1 3FX (United Kingdom); Wong, Yvonne Y.Y. [School of Physics, The University of New South Wales,Sydney NSW 2052 (Australia)

    2015-08-11

    Sterile neutrinos are thermalised in the early Universe via oscillations with the active neutrinos for certain mixing parameters. The most detailed calculation of this thermalisation process involves the solution of the momentum-dependent quantum kinetic equations, which track the evolution of the neutrino phase space distributions. Until now the collision terms in the quantum kinetic equations have always been approximated using equilibrium distributions, but this approximation has never been checked numerically. In this work we revisit the sterile neutrino thermalisation calculation using the full collision term, and compare the results with various existing approximations in the literature. We find a better agreement than would naively be expected, but also identify some issues with these approximations that have not been appreciated previously. These include an unphysical production of neutrinos via scattering and the importance of redistributing momentum through scattering, as well as details of Pauli blocking. Finally, we devise a new approximation scheme, which improves upon some of the shortcomings of previous schemes.

  5. Active-sterile neutrino oscillations in the early Universe with full collision terms

    CERN Document Server

    Hannestad, Steen; Tram, Thomas; Wong, Yvonne Y Y

    2015-01-01

    Sterile neutrinos are thermalised in the early Universe via oscillations with the active neutrinos for certain mixing parameters. The most detailed calculation of this thermalisation process involves the solution of the momentum-dependent quantum kinetic equations, which track the evolution of the neutrino phase space distributions. Until now the collision terms in the quantum kinetic equations have always been approximated using equilibrium distributions, but this approximation has never been checked numerically. In this work we revisit the sterile neutrino thermalisation calculation using the full collision term, and compare the results with various existing approximations in the literature. We find a better agreement than would naively be expected, but also identify some issues with these approximations that have not been appreciated previously. These include an unphysical production of neutrinos via scattering and the importance of redistributing momentum through scattering, as well as details of Pauli bl...

  6. Nonminimal Couplings in the Early Universe: Multifield Models of Inflation and the Latest Observations

    CERN Document Server

    Kaiser, David I

    2015-01-01

    Models of cosmic inflation suggest that our universe underwent an early phase of accelerated expansion, driven by the dynamics of one or more scalar fields. Inflationary models make specific, quantitative predictions for several observable quantities, including particular patterns of temperature anistropies in the cosmic microwave background radiation. Realistic models of high-energy physics include many scalar fields at high energies. Moreover, we may expect these fields to have nonminimal couplings to the spacetime curvature. Such couplings are quite generic, arising as renormalization counterterms when quantizing scalar fields in curved spacetime. In this chapter I review recent research on a general class of multifield inflationary models with nonminimal couplings. Models in this class exhibit a strong attractor behavior: across a wide range of couplings and initial conditions, the fields evolve along a single-field trajectory for most of inflation. Across large regions of phase space and parameter space,...

  7. Auto-Guiding System for CQUEAN (Camera for QUasars in EArly uNiverse)

    CERN Document Server

    Kim, Eunbin; Jeong, Hyenju; Kim, Jinyoung; Kuehne, John; Kim, Dong Han; Kim, Han Geun; Odons, Peter S; Chang, Seunghyuk; Im, Myungshin; Pak, Soojong

    2011-01-01

    To perform imaging observation of optically red objects such as high redshift quasars and brown dwarfs, the Center for the Exploration of the Origin of the Universe (CEOU) recently developed an optical CCD camera, Camera for QUasars in EArly uNiverse(CQUEAN), which is sensitive at 0.7-1.1 um. To enable observations with long exposures, we developed an auto-guiding system for CQUEAN. This system consist of an off-axis mirror, a baffle, a CCD camera, a motor and a differential decelerator. To increase the number of available guiding stars, we designed a rotating mechanism for the off-axis guiding camera. The guiding field can be scammed along the 10 acrmin ring offset from the optical axis of the telescope. Combined with the auto-guiding software of the McDonald Observatory, we confirmed that a stable image can be obtained with an exposure time as long as 1200 seconds.

  8. [CII] At 1 Star Formation in the Early Universe with Zeus (1 and 2)

    Science.gov (United States)

    Ferkinhoff, Carl; Hailey-Dunsheath, S.; Nikola, T.; Oberst, T.; Parshley, S.; Stacey, G.; Benford, D.; staguhn, J.

    2010-01-01

    We report the detection of the [CII] 158 micron fine structure line from six submillimeter galaxies with redshifts between 1.12 and 1.73. This more than doubles the total number of [CII] 158 micron detections reported from high redshift sources. These observations were made with the Redshift(z) and Early Universe Spectrometer(ZEUS) at the Caltech Submillimeter Observatory on Mauna Kea, Hawaii between December 2006 and March 2009. ZEUS is a background limited submm echelle grating spectrometer (Hailey-Dunsheath 2009). Currently we are constructing ZEUS-2. This new instrument will utilize the same grating but will feature a two dimensional transition-edge sensed bolometer array with SQUID multiplexing readout system enabling simultaneous background limited observations in the 200, 340,450 and 650 micron telluric windows. ZEUS-2 will allow for long slit imaging spectroscopy in nearby galaxies and a [CII] survey from z 0.25 to 2.5.

  9. Black hole growth in the early Universe is self-regulated and largely hidden from view.

    Science.gov (United States)

    Treister, Ezequiel; Schawinski, Kevin; Volonteri, Marta; Natarajan, Priyamvada; Gawiser, Eric

    2011-06-15

    The formation of the first massive objects in the infant Universe remains impossible to observe directly and yet it sets the stage for the subsequent evolution of galaxies. Although some black holes with masses more than 10(9) times that of the Sun have been detected in luminous quasars less than one billion years after the Big Bang, these individual extreme objects have limited utility in constraining the channels of formation of the earliest black holes; this is because the initial conditions of black hole seed properties are quickly erased during the growth process. Here we report a measurement of the amount of black hole growth in galaxies at redshift z = 6-8 (0.95-0.7 billion years after the Big Bang), based on optimally stacked, archival X-ray observations. Our results imply that black holes grow in tandem with their host galaxies throughout cosmic history, starting from the earliest times. We find that most copiously accreting black holes at these epochs are buried in significant amounts of gas and dust that absorb most radiation except for the highest-energy X-rays. This suggests that black holes grew significantly more during these early bursts than was previously thought, but because of the obscuration of their ultraviolet emission they did not contribute to the re-ionization of the Universe.

  10. Gravity, black holes and the very early Universe an introduction to general relativity and cosmology

    CERN Document Server

    Chow, Tai L

    2008-01-01

    In the early 1900s, Albert Einstein formulated two theories that would forever change the landscape of physics: the Special Theory of Relativity and the General Theory of Relativity. By 1925, quantum mechanics had been born out of the dissection of these two theories, and shortly after that, relativistic quantum field theory. We now had in place some important ties between the laws of physics and the types of particle interactions the new physics was uncovering. Gravity is one of the four types of forces that are found throughout the universe. In fact, although it is a relatively weak force, it operates at huge distances, and so must be accounted for in any cosmological system. Unfortunately, gravity continues to defy our neat categorization of how all the forces in nature work together. Professor Tai Chow, from the California State University at Stanislaus in Turlock, lays out for us the basic ideas of Einstein, including his law of gravitation, explains the physics behind black holes, and weaves into this a...

  11. CP violation in bilinear R-parity violation and its consequences for the early universe

    Energy Technology Data Exchange (ETDEWEB)

    Cheriguene, Asma; Porod, Werner [Wuerzburg Univ. (Germany). Inst. fuer Theoretische Physik und Astrophysik; Liebler, Stefan [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2014-06-15

    Supersymmetric models with bilinear R-parity violation (BRpV) provide a framework for neutrino masses and mixing angles to explain neutrino oscillation data. We consider CP violation within the new physical phases in BRpV and discuss their effect on the generation of neutrino masses and the decays of the lightest supersymmetric particle (LSP), being a light neutralino with mass ∝100 GeV, at next-to-leading order. The decays affect the lepton and via sphaleron transitions the baryon asymmetry in the early universe. For a rather light LSP, asymmetries generated before the electroweak phase transition via e.g. the Affleck-Dine mechanism are reduced up to two orders of magnitude, but are still present. On the other hand, the decays of a light LSP themselves can account for the generation of a lepton and baryon asymmetry, the latter in accordance to the observation in our universe, since the smallness of the BRpV parameters allows for an out-of-equilibrium decay and sufficiently large CP violation is possible consistent with experimental bounds from the non-observation of electric dipole-moments.

  12. Spacetime deformation effect on the early universe and the PTOLEMY experiment

    Science.gov (United States)

    Horvat, Raul; Trampetic, Josip; You, Jiangyang

    2017-09-01

    Using a fully-fledged formulation of gauge field theory deformed by the spacetime noncommutativity, we study its impact on relic neutrino direct detection, as proposed recently by the PTOLEMY experiment. The noncommutative background tends to influence the propagating neutrinos by providing them with a tree-level vector-like coupling to photons, enabling thus otherwise sterile right-handed (RH) neutrinos to be thermally produced in the early universe. Such a new component in the universe's background radiation has been switched today to the almost fully active sea of non-relativistic neutrinos, exerting consequently some impact on the capture on tritium at PTOLEMY. The peculiarities of our nonperturbative approach tend to reflect in the cosmology as well, upon the appearances of the coupling temperature, above which RH neutrinos stay permanently decoupled from thermal environment. This entails the maximal scale of noncommutativity as well, being of order of 10-4MPl, above which there is no impact whatsoever on the capture rates at PTOLEMY. The latter represents an exceptional upper bound on the scale of noncommutativity coming from phenomenology.

  13. Energy Feedback from X-ray Binaries in the Early Universe

    CERN Document Server

    Fragos, Tassos; Naoz, Smadar; Zezas, Andreas; Basu-Zych, Antara R

    2013-01-01

    X-ray photons, because of their long mean-free paths, can easily escape the galactic environments where they are produced, and interact at long distances with the inter-galactic medium, potentially having a significant contribution to the heating and reionization of the early Universe. The two most important sources of X-ray photons in the Universe are active galactic nuclei (AGN) and X-ray binaries (XRBs). In this Letter we use results from detailed, large scale population synthesis simulations to study the energy feedback of XRBs, from the first galaxies (z~20) until today. We estimate that X-ray emission from XRBs dominates over AGN at z>6-8. The shape of the spectral energy distribution of the emission from XRBs shows no changes with redshift, in contrast to its normalization which evolves by ~4 orders of magnitude, primarily due to the evolution of the cosmic star-formation rate. However, the metallicity and the mean stellar age of a given XRB population affect significantly its X-ray output. Specificall...

  14. CP violation in bilinear R-parity violation and its consequences for the early universe

    CERN Document Server

    Cheriguene, Asma; Porod, Werner

    2014-01-01

    Supersymmetric models with bilinear R-parity violation (BRpV) provide a framework for neutrino masses and mixing angles to explain neutrino oscillation data. We consider CP violation within the new physical phases in BRpV and discuss their effect on the generation of neutrino masses and the decays of the lightest supersymmetric particle (LSP), being a light neutralino with mass $\\sim 100$ GeV, at next-to-leading order. The decays affect the lepton and via sphaleron transitions the baryon asymmetry in the early universe. For a rather light LSP, asymmetries generated before the electroweak phase transition via e.g. the Affleck-Dine mechanism are reduced up to two orders of magnitude, but are still present. On the other hand, the decays of a light LSP themselves can account for the generation of a lepton and baryon asymmetry, the latter in accordance to the observation in our universe, since the smallness of the BRpV parameters allows for an out-of-equilibrium decay and sufficiently large CP violation is possibl...

  15. Home and Community Language Proficiency in Spanish-English Early Bilingual University Students.

    Science.gov (United States)

    Schmidtke, Jens

    2017-09-14

    This study assessed home and community language proficiency in Spanish-English bilingual university students to investigate whether the vocabulary gap reported in studies of bilingual children persists into adulthood. Sixty-five early bilinguals (mean age = 21 years) were assessed in English and Spanish vocabulary and verbal reasoning ability using subtests of the Woodcock-Muñoz Language Survey-Revised (Schrank & Woodcock, 2009). Their English scores were compared to 74 monolinguals matched in age and level of education. Participants also completed a background questionnaire. Bilinguals scored below the monolingual control group on both subtests, and the difference was larger for vocabulary compared to verbal reasoning. However, bilinguals were close to the population mean for verbal reasoning. Spanish scores were on average lower than English scores, but participants differed widely in their degree of balance. Participants with an earlier age of acquisition of English and more current exposure to English tended to be more dominant in English. Vocabulary tests in the home or community language may underestimate bilingual university students' true verbal ability and should be interpreted with caution in high-stakes situations. Verbal reasoning ability may be more indicative of a bilingual's verbal ability.

  16. Early spring mesopelagic carbon remineralization and transfer efficiency in the naturally iron-fertilized Kerguelen area

    Science.gov (United States)

    Jacquet, S. H. M.; Dehairs, F.; Lefèvre, D.; Cavagna, A. J.; Planchon, F.; Christaki, U.; Monin, L.; André, L.; Closset, I.; Cardinal, D.

    2015-03-01

    We report on the zonal variability of mesopelagic particulate organic carbon remineralization and deep carbon transfer potential during the Kerguelen Ocean and Plateau compared Study 2 expedition (KEOPS 2; October-November 2011) in an area of the polar front supporting recurrent massive blooms from natural Fe fertilization. Mesopelagic carbon remineralization (MR) was assessed using the excess, non-lithogenic particulate barium (Baxs) inventories in mesopelagic waters and compared with bacterial production (BP), surface primary production (PP) and export production (EP). Results for this early season study are compared with the results obtained during a previous study (2005; KEOPS 1) for the same area at a later stage of the phytoplankton bloom. Our results reveal the patchiness of the seasonal advancement and of the establishment of remineralization processes between the plateau (A3) and polar front sites during KEOPS 2. For the Kerguelen plateau (A3 site) we observe a similar functioning of the mesopelagic ecosystem during both seasons (spring and summer), with low and rather stable remineralization fluxes in the mesopelagic column (150-400 m). The shallow water column (~500 m), the lateral advection, the zooplankton grazing pressure and the pulsed nature of the particulate organic carbon (POC) transfer at A3 seem to drive the extent of MR processes on the plateau. For deeper stations (>2000 m) located on the margin, inside a polar front meander, as well as in the vicinity of the polar front, east of Kerguelen, remineralization in the upper 400 m in general represents a larger part of surface carbon export. However, when considering the upper 800 m, in some cases, the entire flux of exported carbon is remineralized. In the polar front meander, where successive stations form a time series, two successive events of particle transfer were evidenced by remineralization rates: a first mesopelagic and deep transfer from a past bloom before the cruise, and a second

  17. Geometric dependence of transport and universal behavior in three dimensional carbon nanostructures

    Science.gov (United States)

    Wang, Leizhi; Yin, Ming; Jaroszynski, Jan; Park, Ju-Hyun; Mbamalu, Godwin; Datta, Timir

    2016-09-01

    Carbon nanostructures with the spherical voids exhibit interesting temperature and magnetic field dependent transport properties. By increasing the void size, the structures are tuned from metallic to insulating; in addition, the magnetoresistance (MR) is enhanced. Our investigation in the magnetic fields (B) up to 18 T at temperatures (T) from 250 mK to 20 K shows that at high temperatures (T > 2 K), the MR crosses over from quadratic to a non-saturating linear dependence with increasing magnetic field. Furthermore, all MR data in this temperature regime collapse onto a single curve as a universal function of B/T, following Kohler's rule. Remarkably, the MR also exhibits orientation insensitivity, i.e., it displays a response independent of the direction on the magnetic field.

  18. Ion chemistry in the early universe: revisiting the role of HeH+ with new quantum calculations

    CERN Document Server

    Bovino, Stefano; Gianturco, Francesco A; Galli, Daniele

    2011-01-01

    The role of HeH+ has been newly assessed with the aid of newly calculated rates which use entirely ab initio methods, thereby allowing us to compute more accurately the relevant abundances within the global chemical network of the early universe. A comparison with the similar role of the ionic molecule LiH+ is also presented. Quantum calculations have been carried out for the gas-phase reaction of HeH+ with H atoms with our new in-house code, based on the negative imaginary potential method. Integral cross sections and reactive rate coefficients obtained under the general conditions of early universe chemistry are presented and discussed. With the new reaction rate, the abundance of HeH+ in the early universe is more than one order of magnitude larger than in previous studies. Our more accurate findings further buttress the possibility to detect cosmological signatures of HeH+.

  19. Effect of carbonate chemistry alteration on the early embryonic development of the Pacific oyster (Crassostrea gigas.

    Directory of Open Access Journals (Sweden)

    Frédéric Gazeau

    Full Text Available Ocean acidification, due to anthropogenic CO₂ absorption by the ocean, may have profound impacts on marine biota. Calcareous organisms are expected to be particularly sensitive due to the decreasing availability of carbonate ions driven by decreasing pH levels. Recently, some studies focused on the early life stages of mollusks that are supposedly more sensitive to environmental disturbances than adult stages. Although these studies have shown decreased growth rates and increased proportions of abnormal development under low pH conditions, they did not allow attribution to pH induced changes in physiology or changes due to a decrease in aragonite saturation state. This study aims to assess the impact of several carbonate-system perturbations on the growth of Pacific oyster (Crassostrea gigas larvae during the first 3 days of development (until shelled D-veliger larvae. Seawater with five different chemistries was obtained by separately manipulating pH, total alkalinity and aragonite saturation state (calcium addition. Results showed that the developmental success and growth rates were not directly affected by changes in pH or aragonite saturation state but were highly correlated with the availability of carbonate ions. In contrast to previous studies, both developmental success into viable D-shaped larvae and growth rates were not significantly altered as long as carbonate ion concentrations were above aragonite saturation levels, but they strongly decreased below saturation levels. These results suggest that the mechanisms used by these organisms to regulate calcification rates are not efficient enough to compensate for the low availability of carbonate ions under corrosive conditions.

  20. Early Implementation of Large Scale Carbon Dioxide Removal Projects through the Cement Industry

    Science.gov (United States)

    Zeman, F. S.

    2014-12-01

    The development of large-scale carbon dioxide reduction projects requires high purity CO2and a reactive cation source. A project seeking to provide both of these requirements will likely face cost barriers with current carbon prices. The cement industry is a suitable early implementation site for such projects by virtue of the properties of its exhaust gases and those of waste concrete. Cement plants are the second largest source of industrial CO2 emissions, globally. It is also the second largest commodity after water, has no ready substitute and is literally the foundation of society. Finally, half of the CO2 emissions originate from process reactions rather than fossil fuel combustion resulting in higher flue gas CO2concentrations. These properties, with the co-benefits of oxygen combustion, create a favorable environment for spatially suitable projects. Oxygen combustion involves substituting produced oxygen for air in a combustion reaction. The absence of gaseous N2 necessitates the recirculation of exhaust gases to maintain kiln temperatures, which increase the CO2 concentrations from 28% to 80% or more. Gas exit temperatures are also elevated (>300oC) and can reach higher temperatures if the multi stage pre-heater towers, that recover heat, are re-designed in light of FGR. A ready source of cations can be found in waste concrete, a by-product of construction and demolition activities. These wastes can be processed to remove cations and then reacted with atmospheric CO2 to produce carbonate minerals. While not carbon negative, they represent a demonstration opportunity for binding atmospheric CO2while producing a saleable product (precipitated calcium carbonate). This paper will present experimental results on PCC production from waste concrete along with modeling results for oxygen combustion at cement facilities. The results will be presented with a view to mineral sequestration process design and implementation.

  1. FAR-DEEP: organic carbon isotope chemostratigraphy of early Paleoproterozoic sediments from Fennoscandia

    Science.gov (United States)

    Illing, C. J.; Strauss, H.; Summons, R. E.; Kump, L.; Fallick, A. E.; Melezhik, V.; Far-Deep Scientists

    2010-12-01

    One major objective of the Fennoscandian Arctic Russia - Drilling Early Earth Project (FAR-DEEP) is to reconstruct ancient microbial ecosystems and the evolution of key metabolic pathways during the Archean-Proterozoic Transition (APT). Fifteen drill cores with a total length of 3650m were retrieved in three areas (Imandra/Varzuga and Pechenga Greenstone belts and Onega Basin) in northern Russia. Cores cover a time interval of some 700 my and have archived several important changes in Earth’s environment. Among them, the Great Oxygenation Event (GOE) at ca. 2350 million years ago resulted in large-scale environmental changes (e.g. Melezhik et al., 2005). Of similar importance, but specifically for global carbon cycling, are the Lomagundi-Jatuli Event (LJE; e.g. Melezhik et al., 2007) and the Shunga Event (SE; e.g. Melezhik et al., 2009). This work presents preliminary carbon isotope results for sedimentary organic matter (δ13Corg) contained in the major sedimentary formations cored by FAR-DEEP. The samples were processed via sealed tube combustion. The total variation in δ13Corg between -40 and -17 ‰ agrees well with previously published data (e.g. Eigenbrode and Freeman, 2006). But more informative than the organic carbon isotopic composition alone is the isotopic difference (Δ13C) between the organic (δ13Corg) and carbonate carbon (δ13Ccarb) isotopic composition: Δ13C = δ13Ccarb - δ13Corg This parameter provides information about the isotopic fractionation associated with biosynthesis and carbon cycling (e.g., Des Marais, 2001). Sediments from the lower Kuetsjärvi Formation (core 5A) and the upper part of the Tulomozero Formation (cores 10A, 10B, 11A), covering the LJE, display Δ13C values between 30 and 37‰. This isotopic difference continuous through the SE (cores 12A/B and 13). The broad parallel evolution of δ13Corg and δ13Ccarb indicates that respective perturbations affected the global carbon cycle. However, further refinement will be

  2. Combined oxygen- and carbon-isotope records through the Early Jurassic: multiple global events and two modes of carbon-cycle/temperature coupling

    DEFF Research Database (Denmark)

    Hesselbo, Stephen P.; Korte, Christoph

    2010-01-01

    -isotope signature), but also some significant contrasts (oxygen-isotope based paleotemperatures which provide no evidence for warming). Significant contrast in oxygen- and carbon-isotope co-variation also occurs on a long timescale. There appear to be two modes in the co-variation of carbon and oxygen isotopes...... environmental changes were global has been strongly debated. Nevertheless, partly as a result of the international effort to define Global Stratotype Sections and Points (GSSPs), much more is now being discovered about environmental changes taking place at and around the other Jurassic Age (Stage) boundaries...... that both long-term and short-term carbon-isotope shifts from the UK Early Jurassic represent global changes in carbon cycle balances. The Sinemurian-Pliensbachian boundary event is an event of global significance and shows several similarities to the Toarcian OAE (relative sea-level change, carbon...

  3. Early pregnancy B vitamin status, one carbon metabolism, pregnancy outcome and child development.

    Science.gov (United States)

    Solé-Navais, Pol; Cavallé-Busquets, Pere; Fernandez-Ballart, Joan D; Murphy, Michelle M

    2016-07-01

    Periconception supplementation with folic acid is recommended until 12 gestational weeks to prevent neural tube defects. Doses of folic acid contained in supplements and timing and length of use during pregnancy vary. The effects of status in periconception and pregnancy folate, cobalamin, betaine and their interactions on one carbon metabolism (1C), as well as the global effect of 1C on foetal growth and pregnancy outcome, are reviewed. Results from prospective studies are reviewed. Cessation of folic acid supplement use after the first trimester is associated with a sharp drop in plasma folate status and enhanced conversion of betaine to dimethylglycine. Dimethylglycine production is also higher in mothers with low folate status than in those with normal-high folate status. The effects of high doses of folic acid on one carbon metabolism in mothers with low early pregnancy cobalamin status and on foetal growth are also reviewed. Several studies report that moderately elevated early pregnancy fasting plasma total homocysteine (tHcy) is inversely associated with birth weight and a predictor of intrauterine growth retardation. There is also evidence for increased risk of preterm birth when maternal folate status is low.

  4. In search of early life: Carbonate veins in Archean metamorphic rocks as potential hosts of biomarkers

    Science.gov (United States)

    Peters, Carl A.; Piazolo, Sandra; Webb, Gregory E.; Dutkiewicz, Adriana; George, Simon C.

    2016-11-01

    The detection of early life signatures using hydrocarbon biomarkers in Precambrian rocks struggles with contamination issues, unspecific biomarkers and the lack of suitable sedimentary rocks due to extensive thermal overprints. Importantly, host rocks must not have been exposed to temperatures above 250 °C as at these temperatures biomarkers are destroyed. Here we show that Archean sedimentary rocks from the Jeerinah Formation (2.63 billion yrs) and Carawine Dolomite (2.55 billion yrs) of the Pilbara Craton (Western Australia) drilled by the Agouron Institute in 2012, which previously were suggested to be suitable for biomarker studies, were metamorphosed to the greenschist facies. This is higher than previously reported. Both the mineral assemblages (carbonate, quartz, Fe-chlorite, muscovite, microcline, rutile, and pyrite with absence of illite) and chlorite geothermometry suggest that the rocks were exposed to temperatures higher than 300 °C and probably ∼400 °C, consistent with greenschist-facies metamorphism. This facies leads to the destruction of any biomarkers and explains why the extraction of hydrocarbon biomarkers from pristine drill cores has not been successful. However, we show that the rocks are cut by younger formation-specific carbonate veins containing primary oil-bearing fluid inclusions and solid bitumens. Type 1 veins in the Carawine Dolomite consist of dolomite, quartz and solid bitumen, whereas type 2 veins in the Jeerinah Formation consist of calcite. Within the veins fluid inclusion homogenisation temperatures and calcite twinning geothermometry indicate maximum temperatures of ∼200 °C for type 1 veins and ∼180 °C for type 2 veins. Type 1 veins have typical isotopic values for reprecipitated Archean sea-water carbonates, with δ13CVPDB ranging from - 3 ‰ to 0‰ and δ18OVPDB ranging from - 13 ‰ to - 7 ‰, while type 2 veins have isotopic values that are similar to hydrothermal carbonates, with δ13CVPDB ranging from - 18

  5. Desmin detection by facile prepared carbon quantum dots for early screening of colorectal cancer

    Science.gov (United States)

    Li, Chang-feng; Yan, Zhen-kun; Chen, Li-bo; Jin, Jing-peng; Li, Dan-dan

    2017-01-01

    Abstract Th aim of this study was to develop a new facile chemical method for early screening of colorectal cancer. The -C(O)OH groups modified Carbon Quantum Dots (CQDs) were prepared by an facile innovative route of acid attacking on carbon nanotubes (CNTs). The -C(O)OH groups were further transported into -C(O)Cl groups by SOCl2 treating. The obtained ClCQDs were conjugated onto the anti-Desmin, which were applied for testing the Desmin concentration in serum by using linearly fitted relationship with photoluminescence (PL) intensity. The obtained carbon quantum dots are quasispherical graphite nanocrystals with photoluminescence at about 455 nm. The Desmin with concentration of 1 ng/mL can lead to a decrease of PL intensity for anti-Desmin conjugated CQDs with good linearity. This assay had good specificity for Desmin with in interferential substances of immunoglobulin G (IgG), alpha fetoprotein (AFP), and carcinoembryoic antigen (CEA). A new facile acid attack method was developed to prepare ClCQDs, which could conjugate onto the anti-Desmin for detection of Desmin in serum with high sensitivity and specificity. As the detection limit is lower than 1 ng/ mL, this work provides a promising strategy for the evaluation of colorectal cancer risk with low cost and excellent sensing performance. PMID:28151847

  6. Effects of spacing on early growth rate and carbon sequestration in Pinus brut ia Ten. plantations

    Energy Technology Data Exchange (ETDEWEB)

    Erkan, N.; Aydin, A.C.

    2016-07-01

    Aim of the study: The aim of this study was to analyze the effects of initial spacing on early growth and carbon sequestration rates in Turkish red pine plantations up to 12 years old, established with improved seeds and deep soil cultivation. Area of study: The study was conducted on experimental sites established in two locations within the Turkish red pine natural distribution areas, namely Du acı and Nebiler close to Antalya city. Material and methods: Data were collected from the experimental sites established as a Nelder design (fan-shaped), with 72 rays and 18 arcs (circles), and trees were planted (almost square) at distances ranging from 1.15 to 4.77 m. Soil type of both sites is loamy, with soil clay content varying between 70-87% in Duacı and 51-70% in Nebiler. Soils are deep being more than one m in both sites, but rockier in Nebiler, providing better soil drainage in this site. Main results: The results showed that mean total height was greater at closer spacing than those of wider spacing until age eight. Growth retardation at wider spacing in early years may be related to water loss due to evaporation in hot summer days and weed suppression. Following the age eight, competition among trees appears to be the major factor reducing the growth and carbon fixation. Diameter at breast height and individual tree volume increased, while stand volume, mean annual volume increment and annual carbon storage per hectare considerably decreased for wider spacing. Our results suggest that in order to obtain higher yield and more carbon fixation, short rotation plantations should initially be established in closer spacing, followed by thinning in subsequent years as required by silvicultural concerns. In this context, spacing 3.0 × 1.0 m or 3.0 × 1.5 m (3.0 and 4.5 m2 growing area per tree, respectively) seems to be more plausible, providing farm machinery for maintenance and harvesting. We also found that mean annual volume increment per unit area can be

  7. Clumped isotope thermometry of modern and early Cretaceous molluscan carbonate from high-latitude seas (Invited)

    Science.gov (United States)

    Henkes, G. A.; Price, G. D.; Ambrose, W. G.; Carroll, M. L.; Passey, B. H.

    2010-12-01

    The carbonate clumped isotope thermometer is based on the temperature sensitivity of the relative abundance of carbonate ion groups containing 13C-18O bonds. One application of clumped isotope thermometry is to determine the temperature of ancient seawater from the skeletal material of calcium carbonate-secreting marine organisms. The relationship between Δ47, a parameter describing isotopic clumping, and the temperature of carbonate biomineralization has been well-defined for fish otoliths, corals, foraminifera, and coccolithophore tests, but few data have been published for brachiopods and bivalve mollusks. A comprehensive evaluation of the Δ47-temperature relationship for mollusks is required for paleotemperature interpretations from the marine fossil record. Here we present a more comprehensive calibration for modern mollusks, including bivalves, cephalopods, and gastropods. Further, we focus on a subset of cold water, high-latitude species collected in the northern Barents Sea. The observed Δ47-temperature relationship is similar to the theoretical relationship presented by Guo et al. (2009) but deviates at low temperatures from the original Ghosh et al. (2007) calibration curve. This divergence could be related to methodological differences or unaccounted differences in the biomineralization of mollusks versus that of other carbonate-secreting organisms at low temperature. One advantage of clumped isotope thermometry over traditional oxygen isotope thermometry is that it does not require assumptions about the isotopic composition of the water in which the carbonate formed. This may be particularly useful in Mesozoic paleoceanography where the oxygen isotope value of seawater is uncertain. Using clumped isotope thermometry applied to early Cretaceous (Valangian) belemnite carbonate from the Yatria River, sub-polar Urals, Siberia, we find shell growth temperatures of 20-26°C at a paleolatitude of ~60-65°N. Our data imply average seawater δ18O values of 0

  8. Assessing offsets between the δ13C of sedimentary components and the global exogenic carbon pool across early Paleogene carbon cycle perturbations

    Science.gov (United States)

    Sluijs, Appy; Dickens, Gerald R.

    2012-12-01

    Negative stable carbon isotope excursions (CIEs) across the Paleocene-Eocene thermal maximum (PETM; ˜56 Ma) range between 2‰ and 7‰, even after discounting sections with truncated records. Individual carbon isotope records differ in shape and magnitude from variations in the global exogenic carbon cycle through changes in (1) the relative abundance of mixed components with different δ13C within a measured substrate, (2) isotope fractionation through physiological change, and (3) the isotope composition of the carbon source. All three factors likely influence many early Paleogene δ13C records, especially across the PETM and other hyperthermal events. We apply these concepts to late Paleocene-early Eocene (˜58-52 Ma) records from Lomonosov Ridge, Arctic Ocean. Linear regression analyses show correlations between the δ13C of total organic carbon (TOC) and two proxies for the relative contribution of terrestrial organic components to sediment TOC: the branched and isoprenoid tetraether index and palynomorphs. We use these correlations to subtract the terrestrial component from δ13CTOC and calculate marine organic matter δ13C. The results show that the magnitude of the CIE in δ13CTOC across the PETM is exaggerated relative to the magnitude of the CIE in δ13CMOM by ˜3‰ due to increased contributions of terrestrial organic carbon during the event. Collectively, all carbon isotope records across the PETM and other major climate-carbon cycle perturbations in Earth's history are potentially biased through one or more of the above factors. Indeed, it is highly unlikely that any δ13C record shows the true shape and magnitude of the CIE for the global exogenic carbon cycle. For the PETM, we conclude that CIE in the exogenic carbon cycle is likely CIE.

  9. Dolomitization in Late Jurassic-Early Cretaceous Platform Carbonates (Berdiga Formation), Ayralaksa Yayla (Trabzon), NE Turkey

    Science.gov (United States)

    Yıldız, Merve; Ziya Kırmacı, Mehmet; Kandemir, Raif

    2017-04-01

    ABSTRACT Pontides constitute an E-W trending orogenic mountain belt that extends about 1100 km along the northern side of Turkey from the immediate east of Istanbul to the Georgian border at the east. Tectono-stratigraphically, the Pontides are divided into three different parts: Eastern, Central, and Western Pontides. The Eastern Pontides, including the studied area, comprise an area of 500 km in length and 100 km in width, extending along the southeast coast of the Black Sea from the Kizilirmak and Yesilirmak Rivers in the vicinity of Samsun to the Little Caucasus. This area is bordered by the Eastern Black Sea basin to the north and the Ankara-Erzincan Neotethyan suture zone to the south. The Late Jurassic-Early Cretaceous platform carbonates are widely exposed in E-W direction in the Eastern Pontides (NE Turkey). The Platform carbonates shows varying lithofacies changing from supratidal to platform margin reef laterally and vertically, and was buried until the end of Late Cretaceous. The studied Ayralaksa Yayla (Trabzon, NE Turkey) area comprises one of the best typical exposures of formation in northern zone of Eastern Pontides. In this area, the lower parts of the formation are pervasively dolomitized by fabric-destructive and fabric-preserving replacement dolomite which are Ca-rich and nonstoichiometric (Ca56-66Mg34-44). Replacement dolomites (Rd) are represented by D18O values of -19.0 to -4.2 (VPDB), D13C values of 4.4 to 2.1 \\permil (VPDB) and 87Sr/86Sr ratios of 0.70889 to 0.70636. Petrographic and geochemical data indicate that Rd dolomites are formed prior to compaction at shallow-moderate burial depths from Late Jurassic-Early Cretaceous seawater and/or partly modified seawater as a result of water/rock interaction and they were recrystallized at elevated temperatures during subsequent burial. In the subsequent diagenetic process during the Late Cretaceous when the region became a magmatic arc, as a result of interaction with Early Jurassic volcanic

  10. Cyclic architecture of a carbonate sequence, early Aptian Shuaiba formation, Al Huwaisah field, Oman

    Energy Technology Data Exchange (ETDEWEB)

    Groetsch, J. (Shell Research, Rijswijk (Netherlands))

    1993-09-01

    Sequence stratigraphy of carbonates is a topic of ongoing controversy. In particular, small-scale shallowing-upward cycles can provide some key information needed for interpretation of carbonate sequences and/or third-order sea level changes. The early Aptian Shuaiba Formation in the Al Huwaisah field consists of about 90 m of shallow-water limestones. Throughout the formation, an overall decreasing influx of fine detritus is notable toward the top. The sequence can be subdivided into a basal unit and an overlying unit. Both units are composed of meter-scale shallowing-upward cycles of different composition, which can be recognized in core and well logs. Fourier analysis of the first principle component of a set of well logs (GR, FDC, CNL, Sonic) revealed an abrupt change in spectral behavior between the two units. Toward the top, the spectra are [open quotes]cleaning upward[close quotes] with an increasing pronunciation of a peak grouping of 1: 2: 5, suggesting a better preservation of orbital variations in the upper unit. Preservation of orbital forcing in shallowing-upward cycles requires rapid rates of sedimentation. In addition, increased shallow-water carbonate production on the platform is indicated by the appearance of reefal organisms. Hence, a higher rate of sedimentation and therefore a faster aggradation of the platform is inferred for the upper unit, which could have resulted from an increased rate of relative sea level rise. The sudden facies differentiation on the broad Arabian shelf in the upper part of the early Aptian reflects the development of an intrashelf basin. Changes in rate of relative sea level rise on the Arabian shelf might explain the repeated alternation from an easily correlatable ramp-type sedimentation, with slightly higher input of fine terrigenous sediment (e.g., lower unit of Shuaiba Formation) and a differentiation into platform and intrashelf basin facies due to faster aggradation (e.g., upper unit of Shuaiba Formation).

  11. Energy Feedback from X-ray Binaries in the Early Universe

    Science.gov (United States)

    Fragos, T.; Lehmer, B..; Naoz, S.; Zezas, A.; Basu-Zych, A.

    2013-01-01

    X-ray photons, because of their long mean-free paths, can easily escape the galactic environments where they are produced, and interact at long distances with the intergalactic medium, potentially having a significant contribution to the heating and reionization of the early universe. The two most important sources of X-ray photons in the universe are active galactic nuclei (AGNs) and X-ray binaries (XRBs). In this Letter we use results from detailed, large scale population synthesis simulations to study the energy feedback of XRBs, from the first galaxies (z (redshift) approximately equal to 20) until today.We estimate that X-ray emission from XRBs dominates over AGN at z (redshift) greater than or approximately equal to 6-8. The shape of the spectral energy distribution of the emission from XRBs shows little change with redshift, in contrast to its normalization which evolves by approximately 4 orders of magnitude, primarily due to the evolution of the cosmic star-formation rate. However, the metallicity and the mean stellar age of a given XRB population affect significantly its X-ray output. Specifically, the X-ray luminosity from high-mass XRBs per unit of star-formation rate varies an order of magnitude going from solar metallicity to less than 10% solar, and the X-ray luminosity from low-mass XRBs per unit of stellar mass peaks at an age of approximately 300 Myr (million years) and then decreases gradually at later times, showing little variation for mean stellar ages 3 Gyr (Giga years, or billion years). Finally, we provide analytical and tabulated prescriptions for the energy output of XRBs, that can be directly incorporated in cosmological simulations.

  12. ENERGY FEEDBACK FROM X-RAY BINARIES IN THE EARLY UNIVERSE

    Energy Technology Data Exchange (ETDEWEB)

    Fragos, T.; Zezas, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Lehmer, B. D. [The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 (United States); Naoz, S. [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Basu-Zych, A., E-mail: tfragos@cfa.harvard.edu [NASA Goddard Space Flight Centre, Code 662, Greenbelt, MD 20771 (United States)

    2013-10-20

    X-ray photons, because of their long mean-free paths, can easily escape the galactic environments where they are produced, and interact at long distances with the intergalactic medium, potentially having a significant contribution to the heating and reionization of the early universe. The two most important sources of X-ray photons in the universe are active galactic nuclei (AGNs) and X-ray binaries (XRBs). In this Letter we use results from detailed, large scale population synthesis simulations to study the energy feedback of XRBs, from the first galaxies (z ∼ 20) until today. We estimate that X-ray emission from XRBs dominates over AGN at z ∼> 6-8. The shape of the spectral energy distribution of the emission from XRBs shows little change with redshift, in contrast to its normalization which evolves by ∼4 orders of magnitude, primarily due to the evolution of the cosmic star-formation rate. However, the metallicity and the mean stellar age of a given XRB population affect significantly its X-ray output. Specifically, the X-ray luminosity from high-mass XRBs per unit of star-formation rate varies an order of magnitude going from solar metallicity to less than 10% solar, and the X-ray luminosity from low-mass XRBs per unit of stellar mass peaks at an age of ∼300 Myr and then decreases gradually at later times, showing little variation for mean stellar ages ∼> 3 Gyr. Finally, we provide analytical and tabulated prescriptions for the energy output of XRBs, that can be directly incorporated in cosmological simulations.

  13. Models and (some) Searches for CPT Violation: From Early Universe to the Present Era

    Science.gov (United States)

    Mavromatos, Nick E.

    2017-07-01

    In the talk, I review theoretical models, inspired by quantum gravity, that may violate CPT symmetry. The amount of violation today (which is constrained severely by a plethora of experiments that I will not describe due to lack of space) need not be the same with the one that occurred in the Early Universe,. In certain models, one can obtain a precise temperature dependence of CPT violating effects, which is such that these effects are significant during the radiation era of the Universe, but are damped quickly so that they do not to affect nucleosynthesis and are negligible in the present epoch (that is, beyond experimental detection with the current experimental sensitivity). The CPT Violation (CPTV) in these models may arise from special properties of the background over which the fields of the model are propagating upon and be responsible for the generation of a matter-antimatter asymmetry, where any CP violation effects could only assist in the creation of the asymmetry, the dominant effect being CPTV. However, there are cases, where the CPTV arises as a consequence of an ill-defined CPT operator due to decoherence as a result of quantum gravity environmental degrees of freedom, inaccessible to a low-energy observer. I also discuss briefly the current-era phenomenology of some of the above models; in particular, for the ones involving decoherence-induced CPT violation, I argue that entangled states of neutral mesons (Kaons or B-systems) can provide smoking-gun sensitive tests or even falsify some of these models. If CPT is ill-defined one may also encounter violations of the spin-statistics theorem, with possible consequences for the Pauli Exclusion Principle.

  14. Early Implementation of Universal Health Coverage Among Hypertension Subjects in Sleman District of Yogyakarta

    Directory of Open Access Journals (Sweden)

    Rita Suhadi

    2015-12-01

    Full Text Available Aim: to evaluate the participant rate of the new universal health coverage (UHC and its impact on the hypertensive subjects from the rural area in the Sleman-District of Yogyakarta during the early implementation. Methods: this epidemiological survey of the new UHC implementation was included as an analytical crosssectional study done with cluster random sampling. The subject criteria were aged 30-85 year, not in pregnancy, and signed the informed-consent. Subjects were grouped based on the health coverage disparity and analyzed with chi-square statistics for the hypertension prevalence, awareness, therapy, and control. The additional variables of BMI, education, occupation, income, smoking, diet control, physical activity, and health facilities were grouped into binomial data and analyzed based-on the health coverage disparity. Results: of 926 total subjects, 602 (65.0% subjects had the health coverage including 9.2% of the new UHC. The groups of with and without health coverage were not significantly different in hypertension prevalence, the profile of age, blood pressure, and the proportion of the other variables (p>0.05 except for smoking and physical activities. In the high blood pressure sub-group (n=446, the subjects without health coverage had lower proportion of the hypertension awareness p0.05. Conclusion: the participant rate of new UHC was relatively low at 9.2%. Among the subgroup with ≥140/90mmHg blood pressure, the subjects without health coverage were more likely to have lower hypertension awareness and suboptimal therapy than those with the health coverage program. Key words: universal health coverage, hypertension, awareness, therapy.

  15. The early diagenetic and PETROphysical behaviour of recent cold-water CARbonate mounds in Deep Environments (PETROCARDE)

    Science.gov (United States)

    Foubert, Anneleen; Pirlet, Hans; Thierens, Mieke; de Mol, Ben; Henriet, Jean-Pierre; Swennen, Rudy

    2010-05-01

    Sub-recent cold-water carbonate mounds localized in deeper slope settings on the Atlantic continental margins cannot be any longer neglected in the study of carbonate systems. They clearly play a major role in the dynamics of mixed siliciclastic-carbonate and/or carbonate-dominated continental slopes. Carbonate accumulation rates of cold-water carbonate mounds are about 4 to 12 % of the carbonate accumulation rates of tropical shallow-water reefs but exceed the carbonate accumulation rates of their slope settings by a factor of 4 to 12 (Titschack et al., 2009). These findings emphasize the importance of these carbonate factories as carbonate niches on the continental margins. The primary environmental architecture of such carbonate bodies is well-characterized. However, despite proven evidences of early diagenesis overprinting the primary environmental record (e.g. aragonite dissolution) (Foubert & Henriet, 2009), the extent of early diagenetic and biogeochemical processes shaping the petrophysical nature of mounds is until now not yet fully understood. Understanding (1) the functioning of a carbonate mound as biogeochemical reactor triggering early diagenetic processes and (2) the impact of early diagenesis on the petrophysical behaviour of a carbonate mound in space and through time are necessary (vital) for the reliable prediction of potential late diagenetic processes. Approaching the fossil carbonate mound record, through a profound study of recent carbonate bodies is innovative and will help to better understand processes observed in the fossil mound world (such as cementation, brecciation, fracturing, etc…). In this study, the 155-m high Challenger mound (Porcupine Seabight, SW of Ireland), drilled during IODP Expedition 307 aboard the R/V Joides Resolution (Foubert & Henriet, 2009), and mounds from the Gulf of Cadiz (Moroccan margin) will be discussed in terms of early diagenetic processes and petrophysical behaviour. Early differential diagenesis

  16. The carbon reduction research of teaching staff commuting aided by Google Earth: taking Guangzhou University as an example

    Science.gov (United States)

    Xie, Hongyu; Wang, Xixiang; Zhao, Meichan; Zhao, Huaqing; Lin, Zhien

    2008-10-01

    In this paper, taking Guangzhou University as an example, carbon reduction of teaching staff commuting was researched. Firstly, considering carbon emission of teaching staff commuting is come from the fuel consumption of vehicle used to trip, the routes, schedule, vehicle type, fuel type and fuel consumption per 100 km of service express bus, public bus and private car were investigated from relevant department and web questionnaire in office automation system. Secondly, the routes of service express bus, public bus and private car were drawn in Google earth browser to measure distance. Thirdly, combined the bus schedule, school calendar, curriculum timetable of teacher and fuel consumption per 100 km of all kinds of vehicle, the fuel consumption of service express bus, public bus and private car were computed. Fourthly, carbon emission was calculated according to net calorific factor and calorie carbon emission factors of fuel. Finally, the measures of carbon reduction were discussed. The research results show that teaching staff commuting emitted 455.433 tons carbon in 2005-2006 academic year. And reducing usage rate of private car and adding new service express bus line are efficient measure of carbon reduction. Former measure can reduce 33.6891 tons carbon and about 7.4% of original emission. The latter can reduce 7.6317 tons and about 1.68% of original emission.

  17. The Impact of an Urban Universal Public Prekindergarten Program on Children's Early Numeracy, Language, Literacy, and Executive Function Outcomes

    Science.gov (United States)

    Weiland, Christina; Yoshikawa, Hirokazu

    2011-01-01

    The authors add to and extend the emerging evidence base of the effects of public preschool programs on child school readiness. Using a quasi-experimental, Regression Discontinuity (RD) design, they estimate the impacts of a universal preschool program on children's early numeracy, language, literacy, and executive function skills, both for the…

  18. CELLULAR-DAMAGE AND EARLY METABOLIC FUNCTION OF TRANSPLANTED LIVERS STORED IN EUROCOLLINS OR UNIVERSITY-OF-WISCONSIN SOLUTION

    NARCIS (Netherlands)

    PRUIM, J; TENVERGERT, EM; KLOMPMAKER, IJ; SLOOFF, MJH

    1991-01-01

    In a clinical setting, the effect of Eurocollins (EC) and University of Wisconsin solution (UW) on liver grafts were studied in the early reperfusion phase of liver transplantation. Blood samples were drawn before and after declamping of the portal vein in a group of 11 transplants with EC-perfused

  19. CELLULAR-DAMAGE AND EARLY METABOLIC FUNCTION OF TRANSPLANTED LIVERS STORED IN EUROCOLLINS OR UNIVERSITY-OF-WISCONSIN SOLUTION

    NARCIS (Netherlands)

    PRUIM, J; TENVERGERT, EM; KLOMPMAKER, IJ; SLOOFF, MJH

    1991-01-01

    In a clinical setting, the effect of Eurocollins (EC) and University of Wisconsin solution (UW) on liver grafts were studied in the early reperfusion phase of liver transplantation. Blood samples were drawn before and after declamping of the portal vein in a group of 11 transplants with EC-perfused

  20. Using Electronic Portfolio to Promote Professional Learning Community for Pre-Service Early Childhood Teachers at Alquds University

    Science.gov (United States)

    Khales, Buad

    2016-01-01

    The present study aims to explore whether the electronic portfolio can influence pre-service teachers' education and to examine how professional learning communities develop through electronic portfolios. To achieve this, twenty-four student-teachers taking a course in early childhood education at Al-Quds University participated in a study to…

  1. Climate Cycling on Early Mars Caused by the Carbonate-Silicate Cycle

    Science.gov (United States)

    Kasting, J. F.; Batalha, N. E.; Haqq-Misra, J. D.; Kopparapu, R.

    2016-12-01

    For decades, scientists have tried to explain the evidence for fluvial activity on early Mars, but a consensus has yet to emerge regarding the mechanism for producing it. One hypothesis suggests early Mars was warmed by a thick greenhouse atmosphere [1]. Another suggests early Mars was generally cold but was warmed occasionally by impacts or by episodes of enhanced volcanism [2,3], with warming possibly extended by cirrus clouds [4]. These latter hypotheses struggle to produce the amounts of rainfall needed to form the martian valleys, but are consistent with inferred low rates of weathering compared to Earth. We suggest that both schools of thought are partly correct. Mars experienced dramatic climate cycles with extended periods of glaciation punctuated by warm periods lasting up to 10 Myr [5]. Cycles of repeated glaciation and deglaciation occurred because stellar insolation was low, and because CO2 outgassing could not keep pace with CO2 consumption by silicate weathering followed by deposition of carbonates. In order to deglaciate early Mars, substantial outgassing of molecular hydrogen from Mars' reduced crust and mantle was also required, as our own climate model is unable to do this without adding some greenhouse warming from H2 [6,7]. Our hypothesis can be tested by future Mars exploration that better establishes the time scale for valley formation. References: [1] Pollack JB, Kasting JF, Richardson SM, Poliakoff K. 1987. Icarus 71: 203-24 [2] Halevy I, Head JW. 2014. Nature Geoscience 7: 865-8 [3] Segura TL, Toon OB, Colaprete A, Zahnle K. 2002. Science 298: 1977-80 [4] Urata RA, Toon OB. 2013. Icarus 226: 229-50 [5] Batalha NE, Kopparapu RK, Haqq-Misra JD, Kasting JF. submitted. Climate cycling on early Mars caused by the carbonate-silicate cycle. EPSL [6] Ramirez RM, Kopparapu R, Zugger ME, Robinson TD, Freedman R, Kasting JF. 2014. Nature Geosci 7: 59-63 [7] Batalha N, Domagal-Goldman SD, Ramirez R, Kasting JF. 2015. Icarus 258: 337-49

  2. Rapid and massive carbon injections of the Early Paleogene: The carbonate and planktonic foraminifera records at ODP Site 1215 (Equatorial Pacific Ocean)

    Science.gov (United States)

    Leon Rodriguez, L.; Dickens, G. R.

    2010-12-01

    Models for ocean chemistry indicate that anthropogenic input of CO2 will decrease seawater pH and the concentration of carbonate ion. This should cause dissolution of pelagic carbonate on the seafloor and may reduce biogenic calcification. Stable carbon isotope records spanning the Late Paleocene and Early Eocene show a series of pronounced negative excursions (CIEs) interpreted as massive inputs of carbon. We therefore studied carbonate-rich sediments at Ocean Drilling Program (ODP) Site 1215, which were deposited on the flank of the East Pacific Rise from the Late Paleocene to Early Eocene, to track potential lysocline and ecological changes before, during and after the CIEs. We document four negative CIEs, which correlate to the PETM (Paleocene/Eocene Thermal Maximum, ~55.5 Ma), H1/ETM2 (~53.7 Ma), I1 (~53.2 Ma), and K/X (~52.5 Ma) events. These excursions are characterized by horizons of low carbonate content and an absence of planktonic foraminifers. Shortly after each perturbation, carbonate content and planktonic foraminifer abundance increased dramatically. We interpret these signals as representing time intervals when the lysocline and CCD initially shoaled because of massive carbon addition and subsequently deepened because of accelerated weathering and addition of alkalinity. We observe permanent ecological changes within the photic zone after the PETM. Globanomalinids (intermediate dwellers) more common in the record before the PETM locally disappeared afterwards. In contrast, acarinids and morozovellids (surface dwellers, photosymbont-bearing) were nearly absent before the PETM but become relatively abundant just after. Chiloguembelinids and “Tenuitellids” (intermediate dwellers) are more abundant between the H1/ETM2 and the I1 events, which could be an indication of enhanced carbonate preservation within the recovery phase of the lysocline or conditions that were more favorable for intermediate dwellers. Subbotinids and igorinids are rare in the

  3. Spontaneous B-L breaking as the origin of the hot early universe

    Energy Technology Data Exchange (ETDEWEB)

    Buchmueller, W.; Domcke, V.; Schmitz, K.

    2012-03-15

    The decay of a false vacuum of unbroken B-L symmetry is an intriguing and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase yields hybrid inflation, ending in tachyonic preheating. The dynamics of the B - L breaking Higgs field and thermal processes produce an abundance of heavy neutrinos whose decays generate entropy, baryon asymmetry and gravitino dark matter. We study the phase transition for the full supersymmetric Abelian Higgs model. For the subsequent reheating process we give a detailed time-resolved description of all particle abundances. The competition of cosmic expansion and entropy production leads to an intermediate period of constant 'reheating' temperature, during which baryon asymmetry and dark matter are produced. Consistency of hybrid inflation, leptogenesis and gravitino dark matter implies relations between neutrino parameters and superparticle masses, in particular a lower bound on the gravitino mass of 10 GeV.

  4. Time dependent non-LTE calculations of ionisation in the early universe

    CERN Document Server

    Wehrse, R; Davé, R; Dav\\'e, Romeel

    2005-01-01

    We present a new implicit numerical algorithm for the calculation of the time dependent non-Local Thermodynamic Equilibrium of a gas in an external radiation field that is accurate, fast and unconditionally stable for all spatial and temporal increments. The method is presented as a backward difference scheme in 1-D but can be readily generalised to 3-D. We apply the method for calculating the evolution of ionisation domains in a hydrogen plasma with plane-parallel Gaussian density enhancements illuminated by sources of UV radiation. We calculate the speed of propagation of ionising fronts through different ambient densities and the interaction of such ionising fronts with density enhancements. We show that for a typical UV source that may be present in the early universe, the introduction of a density enhancement of a factor ~10 above an ambient density 10^{-4} atoms/cm^3 could delay the outward propagation of an ionisation front by millions of years. Our calculations show that within the lifetime of a singl...

  5. Test anxiety in mathematics among early undergraduate students in a British university in Malaysia

    Science.gov (United States)

    Karjanto, Natanael; Yong, Su Ting

    2013-03-01

    The level of test anxiety in mathematics subjects among early undergraduate students at the University of Nottingham Malaysia Campus is studied in this article. The sample consists of 206 students taking several mathematics modules who completed the questionnaires on test anxiety just before they entered the venue for midterm examinations. The sample data include the differences in the context of academic levels, gender groups and nationality backgrounds. The level of test anxiety in mathematics is measured using seven Likert questionnaire statements adapted from the Test Anxiety Inventory describing one's emotional feeling before the start of an examination. In general, the result shows that the students who had a lower score expectation were more anxious than those who had a higher score expectation, but that they obtained a better score than the expected score. In the context of academic levels, gender groups and nationality backgrounds, there were no significant correlations between the level of test anxiety and the students' academic performance. The effect size of the correlation values ranged from extremely small to moderate.

  6. A little inflation in the early universe at the QCD phase transition

    CERN Document Server

    Boeckel, Tillmann

    2009-01-01

    We explore a scenario that allows for a strong first order phase-transition of QCD at non-negligible baryon number in the early universe and its possible cosmological observable consequences. The main assumption is a quasi-stable QCD-vacuum state that leads to a short period of inflation, consequently diluting the net baryon to photon ratio to it's today observed value. A strong mechanism for baryogenesis is needed to start out with a baryon asymmetry of order unity, e.g. as provided by Affleck-Dine baryogenesis. The cosmological implications are direct effects on primordial density fluctuations up to dark matter mass scales of 1 - 10 solar masses, change in the spectral slope up to mass scales of 10^6 - 10^7 solar masses, production of primordial magnetic fields with initial strength up to 10^12 Gauss and a gravitational wave spectrum with present day peak strain amplitude of at most h_c = 4.7 * 10^-15 around a frequency of 4*10^-8 Hz. The little QCD inflation scenario could be probed with the upcoming heavy...

  7. A little inflation in the early universe at the QCD phase transition.

    Science.gov (United States)

    Boeckel, Tillmann; Schaffner-Bielich, Jürgen

    2010-07-23

    We explore a scenario that allows for a strong first order phase transition of QCD at a non-negligible baryon number in the early Universe and its possible observable consequences. The main assumption is a quasistable QCD-vacuum state that leads to a short period of inflation, consequently diluting the net baryon to photon ratio to today's observed value. A strong mechanism for baryogenesis is needed to start out with a baryon asymmetry of order unity, e.g., as provided by Affleck-Dine baryogenesis. The cosmological implications are direct effects on primordial density fluctuations up to dark matter mass scales of M{max}∼1-10M{⊙}, change in the spectral slope up to M{max}∼10{6}-10{8}M{⊙}, production of strong primordial magnetic fields and a gravitational wave spectrum with present day peak strain amplitude of up to h{c}(ν{peak})∼5×10{-15} around ν{peak}∼4×10{-8}  Hz.

  8. Squeezed states and graviton-entropy production in the early universe

    Science.gov (United States)

    Giovannini, Massimo

    1994-01-01

    Squeezed states are a very useful framework for the quantum treatment of tensor perturbations (i.e. gravitons production) in the early universe. In particular, the non equilibrium entropy growth in a cosmological process of pair production is completely determined by the associated squeezing parameter and is insensitive to the number of particles in the initial state. The total produced entropy may represent a significant fraction of the entropy stored today in the cosmic blackbody radiation, provided pair production originates from a change in the background metric at a curvature scale of the Planck order. Within the formalism of squeezed thermal states it is also possible to discuss the stimulated emission of gravitons from an initial thermal bath, under the action of the cosmic gravitational background field. We find that at low energy the graviton production is enhanced, if compared with spontaneous creation from the vacuum; as a consequence, the inflation scale must be lowered, in order not to exceed the observed CMB quadrupole anisotropy. This effect is important, in particular, for models based on a symmetry-breaking transition which require, as initial condition, a state of thermal equilibrium at temperatures higher than the inflation scale and in which inflation has a minimal duration.

  9. Mixing of blackbodies: entropy production and dissipation of sound waves in the early Universe

    CERN Document Server

    Khatri, Rishi; Chluba, Jens

    2012-01-01

    Mixing of blackbodies with different temperatures creates a spectral distortion which, at lowest order, is a y-type distortion, indistinguishable from the thermal y-type distortion produced by the scattering of CMB photons by hot electrons residing in clusters of galaxies. This process occurs in the radiation-pressure dominated early Universe, when the primordial perturbations excite standing sound waves on entering the sound horizon. Photons from different phases of the sound waves, having different temperatures, diffuse through the electron-baryon plasma and mix together. This diffusion, with the length defined by Thomson scattering, dissipates sound waves and creates spectral distortions in the CMB. Of the total dissipated energy, 2/3 raises the average temperature of the blackbody part of spectrum, while 1/3 creates a distortion of y-type. It is well known that at redshifts 10^5< z< 2x10^6, comptonization rapidly transforms y-distortions into a Bose-Einstein spectrum. The chemical potential of the B...

  10. Composition and origin of Early Cambrian Tiantaishan phosphorite-Mn carbonate ores, Shaanxi Province, China

    Science.gov (United States)

    Hein, J.R.; Fan, D.; Ye, J.; Liu, T.; Yeh, H.-W.

    1999-01-01

    The Tiantaishan phosphorite-Mn carbonate ores occur in the Early Cambrian Tananpo Formation in complexly folded and faulted rocks located in southern Shaanxi Province. About 65 x 106 tonnes of 17% P2O5 ore reserves exist and Mn-ore reserves are about 8.3 x 106 tonnes of +18% Mn. The stratigraphic sequence in ascending order consists of black phyllite, black to gray phosphorite ore, black phyllite, rhodochrostone ore, Mn mixed-carbonates, and dolostone. Data are presented from microprobe mineral chemistry, whole-rock chemistry, stable isotopes of carbonates, X-ray mineralogy, petrographic and SEM observations, and statistical analysis of chemical data. The dominant ore-forming minerals are hydroxy- and carbonate fluorapatite and Ca rhodochrosite, with Mg kutnahorite and dolomite comprising the Mn mixed-carbonate section. Pyrite occurs in all rock types and alabandite (MnS) occurs throughout the rhodochrostone section. The mean P2O5 content of phosphorite is 31% and argillaceous phosphorite is 16%, while the mean MnO content of rhodochrostone ore is 37%. Phosphorite ores are massive, spheroidal, laminated, and banded, while rhodochrostone ores have oolitic, spheroidal, and granular fabrics. The most distinguishing characteristics of the ores are high total organic carbon (TOC) contents (mean 8.4%) in the phosphorite and high P2O5 contents (mean 2.7%) in the rhodochrostone ore. The atypically high TOC contents in the Tiantaishan phosphorite probably result from very strong productivity leading to high sedimentation rates accompanied by weak reworking of sediments; poor utilization of the organic matter by bacteria; and/or partial replacement of bacterial or algal mats by the apatite. The depositional setting of the ores was the margin of an epicontinental seaway created as a direct consequence of global processes that included break-up of a supercontinent, formation of narrow seaways, creation of extensive continental shelves, overturn of stagnant, metal-rich deep

  11. Environmental impact and magnitude of paleosol carbonate carbon isotope excursions marking five early Eocene hyperthermals in the Bighorn Basin, Wyoming

    NARCIS (Netherlands)

    Abels, H.A.|info:eu-repo/dai/nl/304848018; Lauretano, V.; van Yperen, Anna E.; Hopman, Tarek; Zachos, J.C.; Lourens, L.J.|info:eu-repo/dai/nl/125023103; Gingerich, P.D.; Bowen, G.J.

    2016-01-01

    Transient greenhouse warming events in the Paleocene and Eocene were associated with the addition of isotopically light carbon to the exogenic atmosphere–ocean carbon system, leading to substantial environmental and biotic change. The magnitude of an accompanying carbon isotope excursion (CIE) can b

  12. Stress and hazardous alcohol use: associations with early dropout from university.

    Science.gov (United States)

    Andersson, Claes; Johnsson, Kent O; Berglund, Mats; Ojehagen, Agneta

    2009-09-01

    The transition to studying at university is associated with increased levels of both stress and hazardous alcohol use. The aim of this study is to investigate the influence of these factors on first-year dropout from university studies. Two complete cohorts of university freshmen at two homogeneous universities, one in the north and one in the south of Sweden, were asked to participate in an intervention study. Participants responded to a baseline questionnaire including measures of stress and alcohol use. Official university records showing dropout over 12 months were collected. A multivariate analysis established that high stress and admission to the northern university were associated with dropout from university studies, while symptoms of depression and anxiety as well as hazardous drinking were not. There is a need to address the issue of stress associated with the start of university studies. It seems important to offer stress-reducing interventions, specifically aimed at reducing transitional stress, as soon as students start university.

  13. A simple model of universe describing the early inflation and the late accelerated expansion in a symmetric manner

    Energy Technology Data Exchange (ETDEWEB)

    Chavanis, Pierre-Henri [Laboratoire de Physique Théorique (IRSAMC), CNRS and UPS, Université de Toulouse (France)

    2013-07-23

    We construct a simple model of universe which 'unifies' vacuum energy and radiation on the one hand, and matter and dark energy on the other hand in the spirit of a generalized Chaplygin gas model. Specifically, the phases of early inflation and late accelerated expansion are described by a generalized equation of state p/c{sup 2} = αρ+kρ{sup 1+1/n} having a linear component p = αρc{sup 2} and a polytropic component p = kρ{sup 1+1/n}c{sup 2}. For α= 1/3, n= 1 and k=−4/(3ρ{sub P}), where ρ{sub P}= 5.1610{sup 99} g/m{sup 3} is the Planck density, this equation of state describes the transition between the vacuum energy era and the radiation era. For t≥ 0, the universe undergoes an inflationary expansion that brings it from the Planck size l{sub P}= 1.6210{sup −35} m to a size a{sub 1}= 2.6110{sup −6} m on a timescale of about 23.3 Planck times t{sub P}= 5.3910{sup −44} s (early inflation). When t > t{sub 1}= 23.3t{sub P}, the universe decelerates and enters in the radiation era. We interpret the transition from the vacuum energy era to the radiation era as a second order phase transition where the Planck constant ℏ plays the role of finite size effects (the standard Big Bang theory is recovered for ℏ= 0). For α= 0, n=−1 and k=−ρ{sub Λ}, where ρ{sub Λ}= 7.0210{sup −24} g/m{sup 3} is the cosmological density, the equation of state p/c{sup 2} = αρ+kρ{sup 1+1/n} describes the transition from a decelerating universe dominated by pressureless matter (baryonic and dark matter) to an accelerating universe dominated by dark energy (late inflation). This transition takes place at a size a{sub 2}= 0.204l{sub Λ}. corresponding to a time t{sub 2}= 0.203t{sub Λ} where l{sub Λ}= 4.38 10{sup 26} m is the cosmological length and t{sub Λ}= 1.46 10{sup 18} s the cosmological time. The present universe turns out to be just at the transition between these two periods (t{sub 0}∼t{sub 2}). Our model gives the same results as the standard

  14. Carbonate Geochemistry and Organic Biomarkers Evolutions During the Early Toarcian in the Paris Basin

    Science.gov (United States)

    Hermoso, M.; Le Callonnec, L.; Hautevelle, Y.; Minoletti, F.; Renard, M.

    2006-12-01

    Within the Early Toarcian Oceanic Anoxic event, isotopic perturbations (C, O, Sr, Os, Mo and S) are now well described. Their worldwide occurrences and synchronicity are still under debate and oppose locally controlled mechanisms to global events such as methane hydrates release. We present an integrated study for understanding palaeoceanographical records in the Paris Basin. In order to test the influence of the redox status of the environment, the sedimentological, mineralogical and geochemical (carbonate and organic biomarkers) evolutions of two Early Toarcian sites are studied: Bascharage (Luxemburg) and Sancerre (center of France. A sedimentary particles isolation technique was performed to quantify the contribution of primary calcite (calcareous nannoflora) and diagenetic calcareous particles. The respective isotopic signatures of these particles enable to validate the bulk record and discuss the link between photic-zone and interstitial fluids (water-mass stratification, intensity of DIC remineralization, interstitial fluid migrations). It is demonstrated that both biogenic calcareous particles and early diagenetic macrocrystals record the C-isotope negative shift with similar magnitudes. Molecular biomarkers of the organic matter studied by GC-MS enable to characterize the paleoredox conditions in the photic-zone and the bottom water. The Bascharage section is characterized by permanant anoxic conditions in the photic zone (as shown by the presence of gammacerane, 2,3,6- trimethylalkylbenzenes and isorenieratane typical of Chlorobiaceae and reducing conditions in the sediment: Pr/PhC 34hopanes. The Earliest Toarcian Sancerre deposits are dysoxic and transient euxinic conditions are observed from the second step of the C-isotope decrease in carbonates. This level is also highlighted by generalized reducing conditions (Mn- rich carbonate) due to oxides phase destabilization, beginning of Black Shales deposits and disappearance of benthic life. The biomarker

  15. A Corrosion Sensor for Monitoring the Early-Stage Environmental Corrosion of A36 Carbon Steel

    Directory of Open Access Journals (Sweden)

    Dong Chen

    2014-08-01

    Full Text Available An innovative prototype sensor containing A36 carbon steel as a capacitor was explored to monitor early-stage corrosion. The sensor detected the changes of the surface- rather than the bulk- property and morphology of A36 during corrosion. Thus it was more sensitive than the conventional electrical resistance corrosion sensors. After being soaked in an aerated 0.2 M NaCl solution, the sensor’s normalized electrical resistance (R/R0 decreased continuously from 1.0 to 0.74 with the extent of corrosion. Meanwhile, the sensor’s normalized capacitance (C/C0 increased continuously from 1.0 to 1.46. X-ray diffraction result indicates that the iron rust on A36 had crystals of lepidocrocite and magnetite.

  16. Carbon and nitrogen dynamics in early stages of forest litter decomposition as affected by nitrogen addition

    Institute of Scientific and Technical Information of China (English)

    DENG Xiao-wen; LIU Ying; HAN Shi-jie

    2009-01-01

    The effects of nitrogen (N) availability and tree species on the dynamics of carbon and nitrogen at early stage of decomposition of forest litter were studied in a 13-week laboratory incubation experiment. Fresh litter samples including needle litter (Pinus koraiensis) and two types of broadleaf litters (Quercus mongolica and Tilia amurensis) were collected from a broadleaf-korean pine mixed forest in the northern slope of Changbai Mountain (China). Different doses of N (equal to 0, 30 and 50 kg·ha-1yr-1, respectively, as NH4NO3) were added to litter during the experiment period. The litter decomposition rate expressed as mass loss and respiration rate increased significantly with increasing N availability. The mass loss and cumulative CO2-C emission were higher in leaf litter compared to that in needle litter. The dissolved organic Carbon (DOC) concentrations in litter leachate varied widely between the species, but were not greatly affected by N treatments. Regardless of the N addition rate, both N treatments and species had no significant effect on dissolved organic N (DON) concentrations in litter leachate. About 52·78% of added N was retained in the litter. The percentage of N retention was positively correlated (R2=0.91, p<0.05) with the litter mass loss. This suggested that a forest floor with easily decomposed litter might have higher potential N sink strength than that with more slowly decomposed litter.

  17. Early Jurassic foraminiferal assemblages in platform carbonates of Mt. Krim, central Slovenia

    Directory of Open Access Journals (Sweden)

    Luka Gale

    2017-06-01

    Full Text Available During the Early Jurassic, the subtropical carbonate platforms of the peri-Tethys Ocean experienced signifiant changes in their architectures, as well as in their biota compositions. Shallow-water carbonates from the northern part of the ancient Adriatic Carbonate Platform (External Dinarides were investigated in six sections, which taken together cover the development of the platform from deposition of the uppermost Triassic Main Dolomite to the middle Lower Jurassic, lithiotid limestone. Our aim was to establish a detailed foraminiferal biostratigraphy and to observe the changes in size, abundance and diversity of foraminifera in different types of facies. As a result, the succession was successfully divided into stage or substage levels. Foraminiferal assemblages were shown to experience a gradual change in taxonomic composition (including an increase in the proportion of complex agglutinated forms, a general increase in abundance of specimens, and greater diversity in each facies type, except in bindstone and mudstone. Notable is the difference between Hettangian assemblages, which display fairly uniform compositions in all facies types and the predominance of opportunists, and the post-Hettangian assemblages, which become progressively more species-rich and where the differences in facies are perhaps more pronounced. Changes in the size of the species Meandrovoluta asiagoensis Fugagnoli & Rettori, and of the largest specimen in the assemblages, however, are less clear, but are arguably present. Faunal changes roughly correspond to the gradual change from the flt-top platform of the upper Triassic – Hettangian, where biota would be repeatedly subjected to stressed peritidal conditions, to a platform differentiated into lagoon, sand bars and ephemeral emergent areas, offering numerous habitats and perhaps more stable living conditions for organisms.

  18. High-resolution carbon isotope records of the Toarcian Oceanic Anoxic Event (Early Jurassic) from North America and implications for the global drivers of the Toarcian carbon cycle

    Science.gov (United States)

    Them, T. R.; Gill, B. C.; Caruthers, A. H.; Gröcke, D. R.; Tulsky, E. T.; Martindale, R. C.; Poulton, T. P.; Smith, P. L.

    2017-02-01

    The Mesozoic Era experienced several instances of abrupt environmental change that are associated with instabilities in the climate, reorganizations of the global carbon cycle, and elevated extinction rates. Often during these perturbations, oxygen-deficient conditions developed in the oceans resulting in the widespread deposition of organic-rich sediments - these events are referred to as Oceanic Anoxic Events or OAEs. Such events have been linked to massive injections of greenhouse gases into the ocean-atmosphere system by transient episodes of voluminous volcanism and the destabilization of methane clathrates within marine environments. Nevertheless, uncertainty surrounds the specific environmental drivers and feedbacks that occurred during the OAEs that caused perturbations in the carbon cycle; this is particularly true of the Early Jurassic Toarcian OAE (∼183.1 Ma). Here, we present biostratigraphically constrained carbon isotope data from western North America (Alberta and British Columbia, Canada) to better assess the global extent of the carbon cycle perturbations. We identify the large negative carbon isotope excursion associated with the OAE along with high-frequency oscillations and steps within the onset of this excursion. We propose that these high-frequency carbon isotope excursions reflect changes to the global carbon cycle and also that they are related to the production and release of greenhouse gases from terrestrial environments on astronomical timescales. Furthermore, increased terrestrial methanogenesis should be considered an important climatic feedback during Ocean Anoxic Events and other similar events in Earth history after the proliferation of land plants.

  19. CHAIRMAN'S PREFACE: Nobel Symposium 79: The Birth and Early Evolution of Our Universe

    Science.gov (United States)

    Gustafsson, Bengt; Nilsson, Jan S.; Skagerstam, Bo-Sture

    1991-01-01

    It was in 1986 that we submitted a proposal to organize a Nobel Symposium on the topic "The Birth and Early Evolution of Our Universe", a subject not previously discussed at such a meeting. Our feeling at the time was that it would be appropriate to gather together international expertise on the deep and exciting connections between elementary physics and astrophysics/cosmology. In both these scientific disciplines there are wellknown "standard models"—the Glashow-Weinberg-Salam model of electroweak interactions and the Big-Bang cosmological model. The former model has now been tested to a very high accuracy. Progress in observational cosmology and astrophysics has on the other hand given strong support to the standard Big-Bang model as a realistic framework of cosmological evolution. The interesting fact, of course, is that the two standard models are not independent, and their predictions become interlinked when one considers the early, hot universe. It is now a wonderfully accepted piece of history that the constraint on the number of light neutrinos as obtained from the Big-Bang primordial nucleosynthesis agree very well with recent high-energy laboratory experiments. When our proposal was approved in 1989 we were very happy and honoured to invite a large number of internationally outstanding contributors to take part in the Symposium, almost all of whom were able to participate. It was, however, with deep regret and shock that their sudden deaths prevented us from inviting A Sakharov and Y Zeldovich. Their presence and wisdom was sadly missed. By choosing the beautiful village of Gräftåvallen, outside the town of Östesund, as the location of the Symposium, we hoped to provide a relaxing and stimulating atmosphere and also, possibly, almost twenty hours of sunlight a day for a week. The hosts of Gräftåvallen, Annika and Tommy Hagström, have to be thanked for making our stay both extremely successful and to a memorable experience. Our thanks also go to

  20. FAST MAGNETIC FIELD AMPLIFICATION IN THE EARLY UNIVERSE: GROWTH OF COLLISIONLESS PLASMA INSTABILITIES IN TURBULENT MEDIA

    Energy Technology Data Exchange (ETDEWEB)

    Falceta-Gonçalves, D. [SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS (United Kingdom); Kowal, G. [Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, Rua Arlindo Bettio, 1000, São Paulo, SP 03828-000 (Brazil)

    2015-07-20

    In this work we report on a numerical study of the cosmic magnetic field amplification due to collisionless plasma instabilities. The collisionless magnetohydrodynamic equations derived account for the pressure anisotropy that leads, in specific conditions, to the firehose and mirror instabilities. We study the time evolution of seed fields in turbulence under the influence of such instabilities. An approximate analytical time evolution of the magnetic field is provided. The numerical simulations and the analytical predictions are compared. We found that (i) amplification of the magnetic field was efficient in firehose-unstable turbulent regimes, but not in the mirror-unstable models; (ii) the growth rate of the magnetic energy density is much faster than the turbulent dynamo; and (iii) the efficient amplification occurs at small scales. The analytical prediction for the correlation between the growth timescales and pressure anisotropy is confirmed by the numerical simulations. These results reinforce the idea that pressure anisotropies—driven naturally in a turbulent collisionless medium, e.g., the intergalactic medium, could efficiently amplify the magnetic field in the early universe (post-recombination era), previous to the collapse of the first large-scale gravitational structures. This mechanism, though fast for the small-scale fields (∼kpc scales), is unable to provide relatively strong magnetic fields at large scales. Other mechanisms that were not accounted for here (e.g., collisional turbulence once instabilities are quenched, velocity shear, or gravitationally induced inflows of gas into galaxies and clusters) could operate afterward to build up large-scale coherent field structures in the long time evolution.

  1. Early Implementation of Universal Health Coverage Among Hypertension Subjects in Sleman District of Yogyakarta.

    Science.gov (United States)

    Suhadi, Rita; Linawati, Yunita; Virginia, Dita M; Setiawan, Christianus H

    2015-10-01

    to evaluate the participant rate of the new universal health coverage (UHC) and its impact on the hypertensive subjects from the rural area in the Sleman-District of Yogyakarta during the early implementation. this epidemiological survey of the new UHC implementation was included as an analytical cross-sectional study done with cluster random sampling. The subject criteria were aged 30-85 year, not in pregnancy, and signed the informed-consent. Subjects were grouped based on the health coverage disparity and analyzed with chi-square statistics for the hypertension prevalence, awareness, therapy, and control. The additional variables of BMI, education, occupation, income, smoking, diet control, physical activity, and health facilities were grouped into binomial data and analyzed based-on the health coverage disparity. of 926 total subjects, 602 (65.0%) subjects had the health coverage including 9.2% of the new UHC. The groups of with and without health coverage were not significantly different in hypertension prevalence, the profile of age, blood pressure, and the proportion of the other variables (p>0.05) except for smoking and physical activities. In the high blood pressure sub-group (n=446), the subjects without health coverage had lower proportion of the hypertension awareness p0.05). the participant rate of new UHC was relatively low at 9.2%. Among the subgroup with 140/90mmHg blood pressure, the subjects without health coverage were more likely to have lower hypertension awareness and suboptimal therapy than those with the health coverage program.

  2. Planetary Nebulae As A Laboratory For Molecular Hydrogen in the Early Universe

    Science.gov (United States)

    Sellgren, Kris; Bromm, Volker; Dinerstein, Harriet

    2008-03-01

    We propose to obtain Spitzer IRS observations of the mid-infrared rotational lines of H2 in planetary nebulae (PNe) with very hot central stars, T > 100,000 K. Our primary motivation is to investigate the excitation and cooling of H2 exposed to UV radiation near very hot stars, which can serve as a proxy for conditions in the early universe. Cosmological simulations show that the first stellar generation (Pop. III) had high masses, > 100 Msun, and hot photospheres. The UV radiation they produced and its effect on the thermal state of the ambient H2 is relevant to subsequent star formation because stellar masses are determined by accretion processes which depend on temperature, and the metal-free primordial gas cooled primarily through excited H2. Yet the effects of this radiative feedback are uncertain: for example, whether it triggers or suppresses further star formation, and the resultant characteristic masses of second generation stars, which are key to cosmic reionization. PNe with hot central stars may be the only place where we can study the relevant microphysics. We therefore propose to obtain Spitzer spectra of such nebulae, sampling regions with a range of gas densities and radiation field dilution factors. We will use the results to derive an improved H2 cooling function to be incorporated into state of the art cosmological models. Our targets have been previously observed in the near-infrared H2 lines, so we have confidence that the lower excitation rotational lines are detectable. Evidence already exists that in some PNe the excited rotational states are overpopulated relative to standard fluorescence models, and that this may be related to the presence of Lyman-continuum photons. The observations proposed here will enable us to verify and quantify this phenomenon, and improve our understanding of H2 excitation. Spitzer is the only facility at present - and for at least the next decade - which can accomplish these goals.

  3. Early Retirement from Colleges and Universities: Considerations under the Employee Retirement Income Security Act.

    Science.gov (United States)

    Shapiro, Larry E.

    1980-01-01

    Important considerations for institutions wanting to establish supplementary early retirement benefits to encourage the practice are outlined. Regulations concerning pension plans, tax-sheltered annuities, and deferred compensation are reviewed. Individually negotiated early retirement supplements are not recommended. (MSE)

  4. The Carbon_h-factor: predicting individuals' research impact at early stages of their career.

    Science.gov (United States)

    Carbon, Claus-Christian

    2011-01-01

    Assessing an individual's research impact on the basis of a transparent algorithm is an important task for evaluation and comparison purposes. Besides simple but also inaccurate indices such as counting the mere number of publications or the accumulation of overall citations, and highly complex but also overwhelming full-range publication lists in their raw format, Hirsch (2005) introduced a single figure cleverly combining different approaches. The so-called h-index has undoubtedly become the standard in scientometrics of individuals' research impact (note: in the present paper I will always use the term "research impact" to describe the research performance as the logic of the paper is based on the h-index, which quantifies the specific "impact" of, e.g., researchers, but also because the genuine meaning of impact refers to quality as well). As the h-index reflects the number h of papers a researcher has published with at least h citations, the index is inherently positively biased towards senior level researchers. This might sometimes be problematic when predictive tools are needed for assessing young scientists' potential, especially when recruiting early career positions or equipping young scientists' labs. To be compatible with the standard h-index, the proposed index integrates the scientist's research age (Carbon_h-factor) into the h-index, thus reporting the average gain of h-index per year. Comprehensive calculations of the Carbon_h-factor were made for a broad variety of four research-disciplines (economics, neuroscience, physics and psychology) and for researchers performing on three high levels of research impact (substantial, outstanding and epochal) with ten researchers per category. For all research areas and output levels we obtained linear developments of the h-index demonstrating the validity of predicting one's later impact in terms of research impact already at an early stage of their career with the Carbon_h-factor being approx. 0.4, 0.8, and

  5. A universal carbonate ion effect on stable oxygen isotope ratios in unicellular planktonic calcifying organisms

    Directory of Open Access Journals (Sweden)

    P. Ziveri

    2012-03-01

    Full Text Available The oxygen isotopic composition (δ18O of calcium carbonate of planktonic calcifying organisms is a key tool for reconstructing both past seawater temperature and salinity. The calibration of paloeceanographic proxies relies in general on empirical relationships derived from field experiments on extant species. Laboratory experiments have more often than not revealed that variables other than the target parameter influence the proxy signal, which makes proxy calibration a challenging task. Understanding these secondary or "vital" effects is crucial for increasing proxy accuracy. We present data from laboratory experiments showing that oxygen isotope fractionation during calcification in the coccolithophore Calcidiscus leptoporus and the calcareous dinoflagellate Thoracosphaera heimii is dependent on carbonate chemistry of seawater in addition to its dependence on temperature. A similar result has previously been reported for planktonic foraminifera, supporting the idea that the [CO32−] effect on δ18O is universal for unicellular calcifying planktonic organisms. The slopes of the δ18O/[CO32−] relationships range between –0.0243‰ (μmol kg−1−1 (calcareous dinoflagellate T. heimii and the previously published –0.0022‰ (μmol kg−1−1 (non-symbiotic planktonic foramifera Orbulina universa, while C. leptoporus has a slope of –0.0048 ‰ (μmol kg−1−1. We present a simple conceptual model, based on the contribution of δ18O-enriched HCO3 to the CO32− pool in the calcifying vesicle, which can explain the [CO32−] effect on δ18O for the different unicellular calcifiers. This approach provides a new insight into biological fractionation in calcifying organisms

  6. A universal carbonate ion effect on stable oxygen isotope ratios in unicellular planktonic calcifying organisms

    Directory of Open Access Journals (Sweden)

    P. Ziveri

    2011-08-01

    Full Text Available The oxygen isotopic composition (δ18O of calcium carbonate of planktonic calcifying organisms is a key tool for reconstructing both past seawater temperature and salinity. The calibration of paloeceanographic proxies relies in general on empirical relationships derived from experiments on extant species. Laboratory experiments have more often than not revealed that variables other than the target parameter influence the proxy signal, which makes proxy calibration a challenging task. Understanding these secondary or "vital" effects is crucial for increasing proxy accuracy and possibly for developing new biomarkers. We present data from laboratory experiments showing that oxygen isotope fractionation during calcification in the coccolithophore Calcidiscus leptoporus and the calcareous dinoflagellate Thoracosphaera heimii is dependent on carbonate chemistry of seawater in addition to its dependence on temperature. A similar result has previously been reported for planktonic foraminifera, suggesting that the [CO32−] effect on δ18O is universal for unicellular calcifying planktonic organisms. The slopes of the δ18O/[CO32−] relationships range between −0.0243 (μmol kg−1−1 (calcareous dinoflagellate T. heimii and the previously published 0.0022 (μmol kg−1−1 (non-symbiotic planktonic foramifera Orbulina universa, while C. leptoporus has a slope of 0.0048 (μmol kg−1−1. We present a simple conceptual model, based on the contribution of δ18O-enriched HCO3 to the CO32− pool in the calcifying vesicle, which can explain the [CO32−] effect on δ18O for the different unicellular calcifiers. This approach provides a new insight into biological fractionation in

  7. Crystallographic control on early stages of cataclasis in carbonate fault gouges

    Science.gov (United States)

    Demurtas, Matteo; Smith, Steven A. F.; Fondriest, Michele; Spagnuolo, Elena; Di Toro, Giulio

    2017-04-01

    commonly exhibit only one twin set. We interpret the development of a CPO in calcite grains in the layer underlying the slip zone as a strain accommodation mechanism of the imposed slip rate (or shear stress) during the early stages of deformation in a granular material (i.e., fault gouge). More intense CPOs at high slip rates (i.e., 1 m/s) may be a consequence of rapid strain localisation on a narrow slip zone, with the fabric in the underlying gouge not experiencing significant changes. Conversely, at low slip rates the gouge volume undergoing protracted deformation is larger and cataclasis progressively weakens the intensity of the texture until the CPO disappears. In conclusion, mineral crystallography plays an important role in the material behaviour during the early deformation stages in carbonate fault gouges. An incorporation of twinning and CPO development as strain accommodation mechanisms with other physico-chemical processes active during the seismic cycle will provide a more complete model of gouge friction and microstructural evolution in carbonate rocks.

  8. A cosmological model of the early universe based on ECG with variable $\\Lambda$-term in Lyra geometry

    CERN Document Server

    Saadat, H

    2015-01-01

    In this paper, we study interacting extended Chaplygin gas as dark matter and quintessence scalar field as dark energy with an effective $\\Lambda$-term in Lyra manifold. As we know Chaplygin gas behaves as dark matter at the early universe while cosmological constant at the late time. Modified field equations are given and motivation of the phenomenological models discussed in details. Four different models based on the interaction term are investigated in this work. Then, we consider other models where Extended Chaplygin gas and quintessence field play role of dark matter and dark energy respectively with two different forms of interaction between the extended Chaplygin gas and quintessence scalar field for both constant and varying $\\Lambda$. Concerning to the mathematical hardness of the problems we discuss results numerically and graphically. Obtained results give us hope that proposed models can work as good models for the early universe with later stage of evolution containing accelerated expansion.

  9. A Cosmological Model of the Early Universe Based on ECG with Variable Λ-Term in Lyra Geometry

    Science.gov (United States)

    Saadat, H.

    2016-05-01

    In this paper, we study interacting extended Chaplygin gas as dark matter and quintessence scalar field as dark energy with an effective Λ-term in Lyra manifold. As we know Chaplygin gas behaves as dark matter at the early universe while cosmological constant at the late time. Modified field equations are given and motivation of the phenomenological models discussed in details. Four different models based on the interaction term are investigated in this work. Then, we consider other models where Extended Chaplygin gas and quintessence field play role of dark matter and dark energy respectively with two different forms of interaction between the extended Chaplygin gas and quintessence scalar field for both constant and varying Λ. Concerning to the mathematical hardness of the problems we discuss results numerically and graphically. Obtained results give us hope that proposed models can work as good models for the early universe with later stage of evolution containing accelerated expansion.

  10. Regular black hole remnants and graviatoms with de Sitter interior as heavy dark matter candidates probing inhomogeneity of early universe

    CERN Document Server

    Dymnikova, Irina

    2015-01-01

    We address the question of regular primordial black holes with de Sitter interior, their remnants and gravitational vacuum solitons G-lumps as heavy dark matter candidates providing signatures for inhomogeneity of early universe, which is severely constrained by the condition that the contribution of these objects in the modern density does not exceed the total density of dark matter. Primordial black holes and their remnants seem to be most elusive among dark matter candidates. However, we reveal a nontrivial property of compact objects with de Sitter interior to induce proton decay or decay of neutrons in neutron stars. The point is that they can form graviatoms, binding electrically charged particles. Their observational signatures as dark matter candidates provide also signatures for inhomogeneity of the early universe. In graviatoms, the cross-section of the induced proton decay is strongly enhanced, what provides the possibility of their experimental searches. We predict proton decay paths induced by gr...

  11. Pseudoscalar Fields in Torsionful Geometries of the Early Universe, the Baryon Asymmetry and Majorana Neutrino Mass Generation

    CERN Document Server

    Mavromatos, Nick E

    2015-01-01

    We discuss here a specific field-theory model, inspired from string theory, in which the generation of a matter-antimatter asymmetry in the Cosmos is due to the propagation of fermions in a non-trivial, spherically asymmetric (and hence Lorentz violating) gravitational background that may characterise the epochs of the early universe. The background induces different dispersion relations, hence populations, between fermions and antifermions, and thus CPT Violation (CPTV) already in thermal equilibrium. Species populations may freeze out leading to leptogenesis and baryogenesis. More specifically, after reviewing some generic models of background-induced CPTV in early epochs of the Universe, we consider a string-inspired scenario, in which the CPTV is associated with a cosmological background with torsion provided by the Kalb-Ramond (KR) antisymemtric tensor field of the string gravitational multiplet. In a four-dimensional space time this field is dual to a pseudoscalar ``axion-like'' field. The thermalising ...

  12. Peritidal carbonate cycles induced by carbonate productivity variations:A conceptual model for an isolated Early Triassic greenhouse platform in South China

    Institute of Scientific and Technical Information of China (English)

    Wan Yang; Dan JLehrmann

    2014-01-01

    Eustasy has commonly been invoked to explain peritidal carbonate cyclicity, but is dififcult to explain cycles formed in a greenhouse climate when eustasy is minimal. We propose that peritidal cycles on an Early Triassic isolated carbonate platform in Guizhou, South China, were formed by hierarchical carbonate productivity variations. Most of the 149 shallowing-upward cycles are typically terminated by lfooding over intertidal facies and con-tain rare supratidal facies and no prolonged subaerial exposure. Low-diversity benthos in the platform interior during the post-end-Permian biotic recovery were sensitive to environmental perturbations, which caused variations in benthic sediment productivity in the subtidal carbon-ate factory. The perturbations may be driven by changes in salinity and degree of eutrophica-tion, or repeated platform mini-drowning by anoxic and/or CO2-charged deep water upwelled onto the banktop. They were modulated by Milankovitch orbitally-driven climatic and oceano-graphic factors as suggested by the hierarchical stacking pattern and spectral signals of these cycles. A one-dimensional conceptual model shows that hierarchical productivity variations alone may generate hierarchical peritidal carbonate cycles under conditions of constant sub-sidence and no sea-level lfuctuation.

  13. Towards comprehensive early abortion service delivery in high income countries: insights for improving universal access to abortion in Australia

    OpenAIRE

    2016-01-01

    Background Improving access to safe abortion is an essential strategy in the provision of universal access to reproductive health care. Australians are largely supportive of the provision of abortion and its decriminalization. However, the lack of data and the complex legal and service delivery situation impacts upon access for women seeking an early termination of pregnancy. There are no systematic reviews from a health services perspective to help direct health planners and policy makers to...

  14. The Role of Early Maladaptive Schemas in Prediction of Dysfunctional Attitudes toward Drug Abuse among Students of university

    Directory of Open Access Journals (Sweden)

    NedaNaeemi

    2016-07-01

    Full Text Available Drug addiction as the most serious social issue of the world has different sociological, psychological, legal, and political aspects. In this regard, the purpose of this study is to determine the role of early maladaptive schemas in prediction of dysfunctional attitudes toward drug abuse among students of Islamic Azad Universities in Tehran Province, Iran. Statistical population of this study includes all students of Islamic Azad Universities in Tehran Province during 2013 and sample size is equal to 300 members that are randomly chosen. First, the name of university branches in Tehran Province were determined then three branches were randomly chosen out of them and then 300 members were chosen from those branches using random sampling method. All sample members filled out Young Schema Questionnaire Short Form and Dysfunctional Attitude Scale (DAS toward drug. Data were analyzed through regression correlation method and SPSS22 software. The obtained findings indicated a significant relation (P<0/05 between early maladaptive schemas and dysfunctional attitude toward drug abuse among students. Early maladaptive schemas can predict dysfunctional attitudes toward drug among students.

  15. Minerogenic System of Magnesian Nonmetallic Deposits in Early Proterozoic Mg-rich Carbonate Formations in Eastern Liaoning Province

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In the early Proterozoic the Liryu Formation and Dashiqiao Formation of eastern Liaoning province, China, there are distributed Mg-rich carbonate rock formations, in which large to superlarge deposits of boron, magnesite, talc, Xiuyan jade etc. occur. The formation of these magnesian nonmetallic deposits was related to early Proterozoic evaporates; then these deposits underwent reworking of regional metamorphism and hydrothermal metasomatism during the Lüliang orogeny and tectono-magmatism during the Indosinian-Yanshanian. Among other things, the Mg-rich carbonates formations, minerogenetic structures and ore-forming fluids played a controlling role in the formation of the mineral deposits. The refore, it can be concluded that the mineral deposits are products of combined processes of the coupling of ore source field, fluid field, thermal field (energy field) and stress field under certain time-space conditions in the early Proterozoic and the late-stage superimposed reworking of tectono-magmatism.

  16. Cosmological QCD phase transition in steady non-equilibrium dissipative Ho\\v{r}ava-Lifshitz early universe

    CERN Document Server

    Khodadi, M

    2014-01-01

    We study the phase transition from quark-gluon plasma to hadrons in the early universe in the context of non-equilibrium thermodynamics. According to the standard model of cosmology, a phase transition associated with chiral symmetry breaking after the electro-weak transition has occurred when the universe was about $1-10\\mu s$ old. We focus attention on such a phase transition in the presence of a viscous relativistic cosmological background fluid in the framework of non-detailed balance Ho\\v{r}ava-Lifshitz cosmology within an effective model of QCD. We consider a flat Friedmann-Robertson-Walker Universe filled with a non-causal and causal bulk viscous cosmological fluid respectively and investigate the effects of the running coupling constants of Ho\\v{r}ava-Lifshitz gravity, $\\lambda$, on the evolution of the physical quantities relevant to a description of the early universe, namely, the temperature $T$, scale factor $a$, deceleration parameter $q$ and dimensionless ratio of the bulk viscosity coefficient ...

  17. Architecture and evolution of an Early Permian carbonate complex on a tectonically active island in east-central California

    Science.gov (United States)

    Stevens, Calvin H.; Magginetti, Robert T.; Stone, Paul

    2015-01-01

    The newly named Upland Valley Limestone represents a carbonate complex that developed on and adjacent to a tectonically active island in east-central California during a brief interval of Early Permian (late Artinskian) time. This lithologically unique, relatively thin limestone unit lies within a thick sequence of predominantly siliciclastic rocks and is characterized by its high concentration of crinoidal debris, pronounced lateral changes in thickness and lithofacies, and a largely endemic fusulinid fauna. Most outcrops represent a carbonate platform and debris derived from it and shed downslope, but another group of outcrops represents one or possibly more isolated carbonate buildups that developed offshore from the platform. Tectonic activity in the area occurred before, probably during, and after deposition of this short-lived carbonate complex.

  18. Computational Cosmology: from the Early Universe to the Large Scale Structure

    Directory of Open Access Journals (Sweden)

    Anninos Peter

    2001-01-01

    Full Text Available In order to account for the observable Universe, any comprehensive theory or model of cosmology must draw from many disciplines of physics, including gauge theories of strong and weak interactions, the hydrodynamics and microphysics of baryonic matter, electromagnetic fields, and spacetime curvature, for example. Although it is difficult to incorporate all these physical elements into a single complete model of our Universe, advances in computing methods and technologies have contributed significantly towards our understanding of cosmological models, the Universe, and astrophysical processes within them. A sample of numerical calculations (and numerical methods applied to specific issues in cosmology are reviewed in this article: from the Big Bang singularity dynamics to the fundamental interactions of gravitational waves; from the quark-hadron phase transition to the large scale structure of the Universe. The emphasis, although not exclusively, is on those calculations designed to test different models of cosmology against the observed Universe.

  19. Computational Cosmology: from the Early Universe to the Large Scale Structure

    Directory of Open Access Journals (Sweden)

    Peter Anninos

    1998-09-01

    Full Text Available In order to account for the observable Universe, any comprehensive theory or model of cosmology must draw from many disciplines of physics, including gauge theories of strong and weak interactions, the hydrodynamics and microphysics of baryonic matter, electromagnetic fields, and spacetime curvature, for example. Although it is difficult to incorporate all these physical elements into a single complete model of our Universe, advances in computing methods and technologies have contributed significantly towards our understanding of cosmological models, the Universe, and astrophysical processes within them. A sample of numerical calculations addressing specific issues in cosmology are reviewed in this article: from the Big Bang singularity dynamics to the fundamental interactions of gravitational waves; from the quark--hadron phase transition to the large scale structure of the Universe. The emphasis, although not exclusively, is on thosecalculations designed to test different models of cosmology against the observed Universe.

  20. The Spatial Distribution of Carbon Dust in the Early Solar Nebula and the Carbon Content of Planetesimals

    Science.gov (United States)

    Gail, H.-P.; Trieloff, M.

    2016-08-01

    The oxidation and pyrolysis processes in the chemically active regions of the Solar Nebula are considered that are responsible for the destruction of the pristine carbon inherited from the ISM and its conversion to hydrocarbons and ultimately to CO.

  1. PEGylated Carbon Nanocapsule: A Universal Reactor and Carrier for In Vivo Delivery of Hydrophobic and Hydrophilic Nanoparticles.

    Science.gov (United States)

    Rammohan, Amritha; Mishra, Gargi; Mahaling, Binapani; Tayal, Lokesh; Mukhopadhyay, Ahana; Gambhir, Sanjay; Sharma, Ashutosh; Sivakumar, Sri

    2016-01-13

    We have developed PEGylated mesoporous carbon nanocapsule as a universal nanoreactor and carrier for the delivery of highly crystalline hydrophobic/hydrophilic nanoparticles (NPs) which shows superior biocompatibility, dispersion in body fluids, good biodistribution and NPs independent cellular uptake mechanism. The hydrophobic/hydrophilic NPs without surface modification were synthesized in situ inside the cavities of mesoporous carbon capsules (200-850 nm). Stable and inert nature of carbon capsules in a wide range of reaction conditions like high temperature and harsh solvents, make it suitable for being used as nano/microreactors for the syntheses of a variety of NPs for bioimaging applications, such as NaYF4:Eu(3+)(5%), LaVO4:Eu(3+)(10%), GdVO4:Eu(3+)(10%), Y2O3:Eu(3+)(5%), GdF3:Tb(3+)(10%), Mo, Pt, Pd, Au, and Ag. Multiple types of NPs (Y2O3:Eu(3+)(5%) (hydrophobic) and GdF3:Tb(3+)(10%) (hydrophilic)) were coloaded inside the carbon capsules to create a multimodal agent for magneto-fluorescence imaging. Our in vivo study clearly suggests that carbon capsules have biodistribution in many organs including liver, heart, spleen, lungs, blood pool, and muscles.

  2. Isotopic evolution of the terminal Neoproterozoic and early Cambrian carbon cycle on the northern Yangtze Platform, South China

    Institute of Scientific and Technical Information of China (English)

    GUO Qingjun; LIU Congqiang; Harald STRAUSS; Tatiana GOLDBERG

    2003-01-01

    Profound geotectonic, climatic and biological changes occur during the terminal Neoproterozoic and its transition into the early Cambrian. These are reflected in temporal variations of the chemical and isotopic composition of seawater. We are studying a sequence of sedimentary rocks at the Shatan section, northern Yangtze Platform, Sichuan Province of China. This succession comprises, in ascending stratigraphic order, predominantly calcareous sediments of the Sinian upper Dengying Formation and black shales of the lower Cambrian Guojiaba Formation (time equivalent of Niutitang Fm.). Paleoenvironmental setting represents shallow-water shelf deposits. The objective of our study is to provide temporal records for the isotopic compositions of organic and carbonate carbon throughout this time interval. Organic carbon isotope values display a range between -35.8‰ and -30.1‰ with clear stratigraphic variations. Carbonate carbon isotope data vary between -3.5‰ and +0.5‰. These secular variations are interpreted to reflect perturbations of the global carbon cycle, specifically changes in the fractional burial of organic carbon. However, local conditions have further affected the isotopic signals.

  3. Evolution of Early Cretaceous paleotemperatures: A balance between global carbon burial rates and large igneous provinces activity

    Science.gov (United States)

    Bodin, Stephane; Meissner, Philipp; Janssen, Nico; Steuber, Thomas; Mutterlose, Jörg

    2015-04-01

    The lack of a high-resolution, long-term Early Cretaceous paleotemperature record hampers a full-scale comprehension, as well as a more holistic approach, to Early Cretaceous climate changes. Here we present an extended compilation of belemnite-based oxygen, carbon and strontium isotope records covering the late Berriasian - middle Albian from the Vocontian Basin (SE France). Integrated with paleontological and sedimentological evidences, this dataset clearly demonstrates that three intervals of cold climatic conditions have taken place during the Early Cretaceous greenhouse world. More specifically, these have taken place during (1) the late Valanginian-earliest Hauterivian, (2) the late early Aptian and (3) the latest Aptian - earliest Albian. Each of these intervals is associated with high amplitude sea-level fluctuations, pointing at transient installations of polar ice caps. As evidenced by carbon isotope positive excursions, each cold episode is associated with enhanced burial of organic matter on a global scale. Moreover, there is a very good match between the timing and size of large igneous provinces eruptions and the amplitude of Early Cretaceous warming episodes. Altogether, these observations confirm the instrumental role of atmospheric CO2 variations in the making of Mesozoic climate change. On a long-term perspective, during the Early Cretaceous, the coupling of global paleotemperature and seawater strontium isotopic ratio is best explained by temperature-controlled changes of continental crust weathering rates.

  4. Dramatic decrease of pelagic carbonate production by nannoplankton across the Early Toarcian anoxic event (T-OAE)

    Science.gov (United States)

    Mattioli, Emanuela; Pittet, Bernard; Petitpierre, Laurent; Mailliot, Samuel

    2009-02-01

    In this account we present estimates of nannofossil fluxes in four sections and one borehole all belonging to the Early Jurassic western Tethys. This study aims to map the distribution of pelagic carbonate production across the Early Toarcian anoxic event (T-OAE), and to understand which environmental parameters did control such production. Our results indicate important changes in carbonate production by nannoplankton occurring within the western Tethys and its variations through time. Nannofossil fluxes (specimens per m 2 per year) are extremely low during the T-OAE in all the studied settings. Higher fluxes are encountered in the westernmost part of the Tethys Ocean before the T-OAE, whilst pelagic carbonate production shifted towards the northern margin of the Tethys after the recovery from anoxic conditions. The dramatic decrease in nannoplankton production during the T-OAE has been interpreted in previous works as a biocalcification crisis related to high pCO 2 in the atmosphere/hydrosphere system. Although a high pCO 2 may have lowered the carbonate saturation state of Early Jurassic oceans and finally hampered biocalcification, we speculate that the most important effects of CO 2 increase were indirect, and affected pelagic producers via changes on climate and sea-level. Namely, it seems that precipitation/evaporation budgets and continental runoff that controlled nutrient levels and salinity in surface oceanic waters were important factors for pelagic biocalcifiers.

  5. A Novel Carbon Nanofibers Grown on Glass Microballoons Immunosensor: A Tool for Early Diagnosis of Malaria

    Directory of Open Access Journals (Sweden)

    Emmanuel Gikunoo

    2014-08-01

    Full Text Available This paper presents a novel method for direct detection of Plasmodium falciparum histidine rich protein-2 (PfHRP-2 antigen using carbon nanofiber (CNF forests grown on glass microballoons (NMBs. Secondary antibodies specific to PfHRP-2 densely attached to the CNFs exhibit extraordinary ability for the detection of minute concentrations of Plasmodium species. A sandwich immunoassay protocol was employed, where a glass substrate was used to immobilize primary antibodies at designated capture zones. High signal amplification was obtained in both colorimetric and electrical measurements due to the CNFs through specific binding. As a result, it was possible to detect PfHRP-2 levels as low as 0.025 ng/mL concentration in phosphate buffered saline (PBS using a visual signal within only 1 min of test duration. Lower limits of 0.01 ng/mL was obtained by measuring the electrical resistivity of the capture zone. This method is also highly selective and specific in identifying PfHRP-2 and other Plasmodium species from the same solution. In addition, the stability of the labeling mechanism eliminates the false signals generated by the use of dyes in current malaria rapid diagnostic test kits (MRDTs. Thus, the rapid, sensitive and high signal amplification capabilities of NMBs is a promising tool for early diagnosis of malaria and other infectious diseases.

  6. Plasma-Enabled Carbon Nanostructures for Early Diagnosis of Neurodegenerative Diseases

    Directory of Open Access Journals (Sweden)

    Shafique Pineda

    2014-06-01

    Full Text Available Carbon nanostructures (CNs are amongst the most promising biorecognition nanomaterials due to their unprecedented optical, electrical and structural properties. As such, CNs may be harnessed to tackle the detrimental public health and socio-economic adversities associated with neurodegenerative diseases (NDs. In particular, CNs may be tailored for a specific determination of biomarkers indicative of NDs. However, the realization of such a biosensor represents a significant technological challenge in the uniform fabrication of CNs with outstanding qualities in order to facilitate a highly-sensitive detection of biomarkers suspended in complex biological environments. Notably, the versatility of plasma-based techniques for the synthesis and surface modification of CNs may be embraced to optimize the biorecognition performance and capabilities. This review surveys the recent advances in CN-based biosensors, and highlights the benefits of plasma-processing techniques to enable, enhance, and tailor the performance and optimize the fabrication of CNs, towards the construction of biosensors with unparalleled performance for the early diagnosis of NDs, via a plethora of energy-efficient, environmentally-benign, and inexpensive approaches.

  7. A warm or a cold early Earth? New insights from a 3-D climate-carbon model

    Science.gov (United States)

    Charnay, Benjamin; Le Hir, Guillaume; Fluteau, Frédéric; Forget, François; Catling, David C.

    2017-09-01

    Oxygen isotopes in marine cherts have been used to infer hot oceans during the Archean with temperatures between 60 °C (333 K) and 80 °C (353 K). Such climates are challenging for the early Earth warmed by the faint young Sun. The interpretation of the data has therefore been controversial. 1D climate modeling inferred that such hot climates would require very high levels of CO2 (2-6 bars). Previous carbon cycle modeling concluded that such stable hot climates were impossible and that the carbon cycle should lead to cold climates during the Hadean and the Archean. Here, we revisit the climate and carbon cycle of the early Earth at 3.8 Ga using a 3D climate-carbon model. We find that CO2 partial pressures of around 1 bar could have produced hot climates given a low land fraction and cloud feedback effects. However, such high CO2 partial pressures should not have been stable because of the weathering of terrestrial and oceanic basalts, producing an efficient stabilizing feedback. Moreover, the weathering of impact ejecta during the Late Heavy Bombardment (LHB) would have strongly reduced the CO2 partial pressure leading to cold climates and potentially snowball Earth events after large impacts. Our results therefore favor cold or temperate climates with global mean temperatures between around 8 °C (281 K) and 30 °C (303 K) and with 0.1-0.36 bar of CO2 for the late Hadean and early Archean. Finally, our model suggests that the carbon cycle was efficient for preserving clement conditions on the early Earth without necessarily requiring any other greenhouse gas or warming process.

  8. Peritidal carbonate cycles induced by carbonate productivity variations:A conceptual model for an isolated Early Triassic greenhouse platform in South China

    Institute of Scientific and Technical Information of China (English)

    Wan; Yang; Dan; J.Lehrmann

    2014-01-01

    Eustasy has commonly been invoked to explain peritidal carbonate cyclicity,but is difficult to explain cycles formed in a greenhouse climate when eustasy is minimal.We propose that peritidal cycles on an Early Triassic isolated carbonate platform in Guizhou,South China,were formed by hierarchical carbonate productivity variations.Most of the 149 shallowing-upward cycles are typically terminated by flooding over intertidal facies and contain rare supratidal facies and no prolonged subaerial exposure.Low-diversity benthos in the platform interior during the post-end-Permian biotic recovery were sensitive to environmental perturbations,which caused variations in benthic sediment productivity in the subtidal carbonate factory.The perturbations may be driven by changes in salinity and degree of eutrophication,or repeated platform mini-drowning by anoxic and/or CO2-charged deep water upwelled onto the banktop.They were modulated by Milankovitch orbitally-driven climatic and oceanographic factors as suggested by the hierarchical stacking pattern and spectral signals of these cycles.A one-dimensional conceptual model shows that hierarchical productivity variations alone may generate hierarchical peritidal carbonate cycles under conditions of constant subsidence and no sea-level fluctuation.

  9. Astronomy in the early years of elementary education: a partnership between university and school

    Science.gov (United States)

    Barai, A.; Carvalho Neto, J. T.; Garrido, D.; Ityanagui, G.; Navi, M.

    2016-12-01

    This paper describes the interaction and partnership experience between a school and one of the Federal University of São Carlos (UFSCar)campi, both located in Araras, SP, aiming to teach and promote astronomy and astronautics knowledge among students of the first five years of Elementary Education. This initiative made use of Brazilian Olympiad of Astronomy and Astronautics as a motivating event for the theme exploration. The actions were divided into two fronts: an improvement course for the school teachers conducted by university professors and lectures for students by UFSCar students under the guidance of university teachers and the school coordinators. By the observed results, we noticed the importance of narrowing the distance school-university, promoting learning for both institutions and helping to raise the level of education from elementary school to college.

  10. The Construction and Empirical Analysis of Financial Risk Early Warning System in Colleges and Universities

    Directory of Open Access Journals (Sweden)

    Dai Jiaxu

    2017-03-01

    Full Text Available In recent years, China's higher education into the period of rapid development, high growth will inevitably bring high demand for financial support, but the government investment can not keep up with the pace of development of colleges and universities, so many colleges and universities choose bank loans, blind expansion will be out of control Resulting in college financial crisis. This paper proposes a method to construct the financial risk evaluation model of colleges and universities. The model is based on the specific risk index system, and uses the analytic hierarchy process and Delphi expert scoring method as the theoretical basis. The model can calculate the type and level of financial risk in colleges and universities, and provide support for the system decision-making.

  11. Underestimated effects of low temperature during early growing season on carbon sequestration of a subtropical coniferous plantation

    Directory of Open Access Journals (Sweden)

    W.-J. Zhang

    2011-06-01

    Full Text Available The impact of air temperature in early growing season on the carbon sequestration of a subtropical coniferous plantation was discussed through analyzing the eddy flux observations at Qianyanzhou (QYZ site in southern China from 2003 to 2008. This site experienced two cold early growing seasons (with temperature anomalies of 2–5 °C in 2005 and 2008, and a severe summer drought in 2003.
    Results indicated that the low air temperature from January to March was the major factor controlling the inter-annual variations in net carbon uptake at this site, rather than the previously thought summer drought. The accumulative air temperature from January to February showed high correlation (R2=0.970, p<0.001 with the annual net ecosystem production (NEP. This was due to the controls of early-month temperature on the plant phenology developing and the growing season length at this subtropical site. The cold spring greatly shortened the growing season length and therefore reduced the carbon uptake period. The eddy flux observations showed a carbon loss of 4.04 g C m−2 per growing-season day at this coniferous forest site. On the other hand, the summer drought also reduced the net carbon uptake strength because the photosynthesis was more sensitive to water deficit stress than the ecosystem respiration. However, the impact of summer drought occurred within a relatively shorter period and the carbon sequestration went back to the normal level once the drought was relieved.

  12. Universe

    CERN Document Server

    2011-01-01

    Updated for 2011, the Universe, is one book in the Britannica Illustrated Science Library Series that covers today's most popular science topics, from digital TV to microchips to touchscreens and beyond. Perennial subjects in earth science, life science, and physical science are all explored in detail. Amazing graphics-more than 1,000 per title-combined with concise summaries help students understand complex subjects. Correlated to the science curriculum in grades 5-9, each title also contains a glossary with full definitions for vocabulary.

  13. Universe

    CERN Document Server

    2009-01-01

    The Universe, is one book in the Britannica Illustrated Science Library Series that is correlated to the science curriculum in grades 5-8. The Britannica Illustrated Science Library is a visually compelling set that covers earth science, life science, and physical science in 16 volumes.  Created for ages 10 and up, each volume provides an overview on a subject and thoroughly explains it through detailed and powerful graphics-more than 1,000 per volume-that turn complex subjects into information that students can grasp.  Each volume contains a glossary with full definitions for vocabulary help and an index.

  14. Inflation of the early cold Universe filled with a nonlinear scalar field and a nonideal relativistic Fermi gas

    Energy Technology Data Exchange (ETDEWEB)

    Pashitskii, E. A., E-mail: pashitsk@iop.kiev.ua; Pentegov, V. I., E-mail: pentegov@iop.kiev.ua [National Academy of Sciences of Ukraine, Institute of Physics (Ukraine)

    2017-03-15

    We consider a possible scenario for the evolution of the early cold Universe born from a fairly large quantum fluctuation in a vacuum with a size a{sub 0} ≫ l{sub P} (where l{sub P} is the Planck length) and filled with both a nonlinear scalar field φ, whose potential energy density U(φ) determines the vacuum energy density λ, and a nonideal Fermi gas with short-range repulsion between particles, whose equation of state is characterized by the ratio of pressure P(n{sub F}) to energy density ε(n{sub F}) dependent on the number density of fermions n{sub F}. As the early Universe expands, the dimensionless quantity ν(n{sub F}) = P(n{sub F})/ε(n{sub F}) decreases with decreasing n{sub F} from its maximum value ν{sub max} = 1 for n{sub F} → ∞ to zero for n{sub F} → 0. The interaction of the scalar and gravitational fields, which is characterized by a dimensionless constant ξ, is proportional to the scalar curvature of four-dimensional space R = κ[3P(n{sub F})–ε(n{sub F})–4λ] (where κ is Einstein’s gravitational constant), and contains terms both quadratic and linear in φ. As a result, the expanding early Universe reaches the point of first-order phase transition in a finite time interval at critical values of the scalar curvature R = R{sub c} =–μ{sup 2}/ξ and radius a{sub c} ≫ a{sub 0}. Thereafter, the early closed Universe “rolls down” from the flat inflection point of the potential U(φ) to the zero potential minimum in a finite time. The release of the total potential energy of the scalar field in the entire volume of the expanding Universe as it “rolls down” must be accompanied by the production of a large number of massive particles and antiparticles of various kinds, whose annihilation plays the role of the Big Bang. We also discuss the fundamental nature of Newton’ gravitational constant G{sub N}.

  15. Early

    Directory of Open Access Journals (Sweden)

    Kamel Abd Elaziz Mohamed

    2014-04-01

    Conclusion: Early PDT is recommended for patients who require prolonged tracheal intubation in the ICU as outcomes like the duration of mechanical ventilation length of ICU stay and hospital stay were significantly shorter in early tracheostomy.

  16. A Course in Early Chemistry for Undergraduates. A Speculative Experiment in Historical Modeling at the Donetsk State University

    Science.gov (United States)

    Rodygin, Mikhail Yu.; Rodygina, Irene V.

    1998-10-01

    Analysis of the world's teaching practices in the history of chemistry shows us that, despite the common time shortage for general educational courses, serious attention should be focused on the early stages of science development. Studies on the history of early chemistry allow students to trace the origins and development of fundamental chemical principles and concepts, to recognize tight relationships between the past and present of human society, and, at last, to obtain broader professional knowledge. An advanced course in the history of early chemistry was taught for senior students at the Donetsk State University, Ukraine. The important constituents of the course were studies on the original works of ancient authors as well as development of the students' ability to absorb and interpret the material adequately. Discussion of general problems in natural history was considered an important part of the education. Thus, the course was based on discussions of selected topics. Throughout the course, the history of chemistry was considered mostly from Biblical and Aristotelian standpoints. This peculiarity makes the teaching approach quite close to approaches used at medieval European universities. It allows us to consider the course as an experiment in speculative historical modeling. Reconstruction of medieval scholastic approaches may reveal original and new pathways to the unveiling of numerous mysteries still remaining in the history of natural science.

  17. M-theory And Superstring Cosmology Brane Gases In The Early Universe And Nonsingular Gravity

    CERN Document Server

    Easson, D A

    2002-01-01

    This thesis will examine two major themes in modern cosmology. The first part of the thesis is concerned with the interface of superstring theory and M-theory with cosmology. We begin by providing a general background of various superstring cosmological models. In particular, we focus on the “Brane Gas” model of string cosmology (BGC) which was developed, in part, by the author. In this scenario the initial state of the Universe is taken to be small, dense and hot with all fundamental degrees of freedom near thermal equilibrium. Such a starting point is in close analogy with the Standard Big-Bang (SBB) model. The topology of the Universe is assumed to be toroidal in all nine spatial dimensions and the Universe is filled with a gas of p- branes. The dynamics of winding modes allow, at most, three spatial dimensions to become large, thus explaining the origin of our macroscopic 3 + 1-dimensional Universe. Specific solutions that are found within the model exhibit loitering, i.e. the Universe...

  18. The influence of ultra-high-energy cosmic rays on star formation in the early universe

    CERN Document Server

    Vasiliev, E O; Shchekinov, Yu.A.

    2006-01-01

    The presence of ultra-high-energy cosmic rays (UHECR) results in an increase in the degree of ionization in the post-recombination Universe, which stimulates the efficiency of the production of H$_2$ molecules and the formation of the first stellar objects. As a result, the onset of the formation of the first stars is shifted to higher redshifts, and the masses of the first stellar systems decrease. As a consequence, a sufficient increase in the ionizing radiation providing the reionization of the Universe can take place. We discuss possible observational manifestations of these effects and their dependence on the parameters of UHECR.

  19. Early Carboniferous (Tournasian-early Visean) global paleogeography, Paleostorm tracts, and the distribution of Waulsortian and Waulsortian-like carbonate mud mounds

    Energy Technology Data Exchange (ETDEWEB)

    King, D.T. Jr. (Auburn Univ., AL (USA))

    1990-05-01

    Tournasian-early Visean mud mounds (i.e., Waulsortian and Waulsortian-like mounds) are unlike other carbonate buildups in the stratigraphic record because they lack an identifiable frame-building organism. Waulsortian mounds are comprised mainly of carbonate mud; Waulsortian-like mounds are mud-rich and contain a significant percent of skeletal grains, especially crinoids and bryozoa. This study has revealed that all of the reported Waulsortian and Waulsortian-like mounds developed in low paleolatitudes either on the southern shelf margin of the Laurussian paleocontinent or in the Laurussian interior seaway. Waulsortian and Waulsortian-like mounds are specifically not present in low-latitude regions of other paleocontinents. As Tournasian-early Visean carbonate deposition was widespread in the range of 30{degree}N to 10{degree}S, the very restricted paleogeographic distribution of Waulsortian and Waulsortian-like mound locations suggests a mechanism or set of conditions that effectively limited the distribution of mud mounds. Considering the Tournasian-early Visean distribution of paleocontinents and the principles that govern the movement of modern hurricanes, tropical storms, and winter storms, the tracts of hurricanes, tropical storms, and winter storms probably crossed all main submerged paleocontinental areas except the southern Laurussian shelf margin and the Laurussian interior seaway, the two areas where mud mounds developed. The lack of storm energy in these two large areas of Laurussia provided long-term stability and thus enhanced the growth prospects of the frame-deficient Waulsortian and Waulsortian-like mud mounds. Lack of extensive periodic wave reworking and other storm-induced devastation helps to account for enigmatic features such as general mound symmetry, great size, high depositional relief (as much as 220 m), and side steepness (as steep as 50{degree}).

  20. Geochemical evidence for subduction in the early Archaean from quartz-carbonate-fuchsite mineralization, Isua Supracrustal Belt, West Greenland

    DEFF Research Database (Denmark)

    Pope, Emily Catherine; Rosing, Minik Thorleif; Bird, Dennis K.

    Quartz, carbonate and fuchsite (chromian muscovite) is a common metasomatic assemblage observed in orogenic gold systems, both in Phanerozoic convergent margin settings, and within supracrustal and greenstone belts of Precambrian rocks. Geologic and geochemical observations in younger orogenic...... systems suggest that ore-forming metasomatic fluids are derived from subduction-related devolitilization reactions, implying that orogenic Au-deposits in Archaean and Proterozoic supracrustal rock suites are related to subduction-style plate tectonics beginning early in Earth history. Justification...

  1. LiHe$^+$ in the early Universe: a full assessment of its reaction network and final abundances

    CERN Document Server

    Bovino, Stefano; Galli, Daniele; Tacconi, Mario; Gianturco, Francesco A

    2012-01-01

    We present the results of quantum calculations based on entirely ab initio methods for a variety of molecular processes and chemical reactions involving the LiHe$^+$ ionic polar molecule. With the aid of these calculations we derive accurate reaction rates and fitting expressions valid over a range of gas temperatures representative of the typical conditions of the pregalactic gas. With the help of a full chemical network, we then compute the evolution of the abundance of LiHe$^+$ as function of redshift in the early Universe. Finally, we compare the relative abundance of LiHe$^+$ with that of other polar cations formed in the same redshift interval.

  2. Environmental impact and magnitude of paleosol carbonate carbon isotope excursions marking five early Eocene hyperthermals in the Bighorn Basin, Wyoming

    Science.gov (United States)

    Abels, Hemmo A.; Lauretano, Vittoria; van Yperen, Anna E.; Hopman, Tarek; Zachos, James C.; Lourens, Lucas J.; Gingerich, Philip D.; Bowen, Gabriel J.

    2016-05-01

    Transient greenhouse warming events in the Paleocene and Eocene were associated with the addition of isotopically light carbon to the exogenic atmosphere-ocean carbon system, leading to substantial environmental and biotic change. The magnitude of an accompanying carbon isotope excursion (CIE) can be used to constrain both the sources and amounts of carbon released during an event and also to correlate marine and terrestrial records with high precision. The Paleocene-Eocene Thermal Maximum (PETM) is well documented, but CIE records for the subsequent warming events are still rare, especially from the terrestrial realm.Here, we provide new paleosol carbonate CIE records for two of the smaller hyperthermal events, I1 and I2, as well as two additional records of Eocene Thermal Maximum 2 (ETM2) and H2 in the Bighorn Basin, Wyoming, USA. Stratigraphic comparison of this expanded, high-resolution terrestrial carbon isotope history to the deep-sea benthic foraminiferal isotope records from Ocean Drilling Program (ODP) sites 1262 and 1263, Walvis Ridge, in the southern Atlantic Ocean corroborates the idea that the Bighorn Basin fluvial sediments record global atmospheric change. The ˜ 34 m thicknesses of the eccentricity-driven hyperthermals in these archives corroborate precession forcing of the ˜ 7 m thick fluvial overbank-avulsion sedimentary cycles. Using bulk-oxide mean-annual-precipitation reconstructions, we find soil moisture contents during the four younger hyperthermals that are similar to or only slightly wetter than the background, in contrast with soil drying observed during the PETM using the same proxy, sediments, and plant fossils.The magnitude of the CIEs in soil carbonate for the four smaller, post-PETM events scale nearly linearly with the equivalent event magnitudes documented in marine records. In contrast, the magnitude of the PETM terrestrial CIE is at least 5 ‰ smaller than expected based on extrapolation of the scaling relationship established

  3. The first three minutes - 1990 version. [of early universe after Big Bang

    Science.gov (United States)

    Schramm, David N.

    1991-01-01

    The present state of understanding of what occurred in the universe's first three minutes is reviewed. Emphasis is on the events that lead to potentially observable consequences and that are model-independent or at least generic to broad classes of models. Inflation, phase transitions, dark matter, and nucleosynthesis are summarized.

  4. Levels of Evidence: Universal Newborn Hearing Screening (UNHS) and Early Hearing Detection and Intervention Systems (EHDI)

    Science.gov (United States)

    Yoshinaga-Itano, Christine

    2004-01-01

    Levels of evidence differ according to the audience addressed. Implementation of universal newborn hearing screening requires responses to a complex myriad of diverse groups: the general public, families with children who are deaf or hard of hearing, the deaf and hard of hearing communities, hospital administrators, physicians (pediatricians,…

  5. Early Participation in the American College and University Presidents Climate Commitment

    Science.gov (United States)

    White, Stacey Swearingen

    2009-01-01

    Purpose: The purpose of this paper is to describe and analyze those US campuses that became signatories of the American College and University Presidents Climate Commitment (ACUPCC) during the charter membership period of December 2006 through September 15, 2007. Design/methodology/approach: The paper draws on literature in organizational change,…

  6. Developmentally Universal Practice: Visioning Innovative Early Childhood Pedagogy for Meeting the Needs of Diverse Learners

    Science.gov (United States)

    Harris, Kathleen I.

    2015-01-01

    Although developmentally appropriate practice (DAP) has strong merits, there are considerations pertaining to its development and implementation which must be raised. In order for educators to include diverse voices of young children, the time has come for a new conversation to unfold introducing developmentally universal practice (DUP). With this…

  7. Transformational Learning and Community Development: Early Reflections on Professional and Community Engagement at Macquarie University

    Science.gov (United States)

    Rawlings-Sanaei, Felicity; Sachs, Judyth

    2014-01-01

    Professional and Community Engagement (PACE) at Macquarie University offers undergraduate students experiential learning opportunities with local, regional, and international partners. In PACE projects, students work toward meeting the partner's organizational goals while they develop their capabilities, learn through the process of engagement,…

  8. Quantum field theory in curved space-time and the early Universe

    OpenAIRE

    Grib, A. A.; Pavlov, Yu. V.

    2002-01-01

    New results on finite density of particle creation for nonconformal massive scalar particles in Friedmann Universe as well as new counterterms in dimensions higher than 5 are presented. Possible role of creation of superheavy particles for explaining observable density of visible and dark matter is discussed.

  9. Late Paleocene–early Eocene carbon isotope stratigraphy from a near-terrestrial tropical section and antiquity of Indian mammals

    Indian Academy of Sciences (India)

    A Samanta; A Sarkar; M K Bera; Jyotsana Rai; S S Rathore

    2013-02-01

    Late Paleocene to early Eocene (∼56 to 51 Ma) interval is characterized by five distinct transient warming (hyperthermal) events (Paleocene–Eocene thermal maximum (PETM), H1/ETM2/ELMO, H2, I1 and I2) in a super greenhouse globe associated with negative carbon isotope excursions (CIEs). Although well-documented marine records exist at different latitudes, terrestrial PETM sections are rare. In particular, almost no terrestrial records of either the PETM or early Eocene hyperthermals (EEHs) are yet available from the tropics. Further, evolution of modern order of mammals near the PETM has been recorded in many northern continents; however, the response of mammals in the tropics to these warming events is unknown. A tropical terrestrial record of these hyperthermal/CIE events, encompassing the earliest modern order mammal bearing horizon from India, can therefore be vital in understanding climatic and biotic evolution during the earliest Cenozoic time. Here, for the first time, we report high resolution carbon isotope (13C) stratigraphy, nannofossil, and Sr isotope ratio of marine fossil carbonate from the Cambay Shale Formation of Western India. The record shows complete preservation of all the above CIE events, including the PETM, hitherto unknown from the equatorial terrestrial records. 13C chemostratigraphy further suggests that at least the present early Eocene mammal-bearing horizon, recently discovered at Vastan, does not support the `out of India' hypothesis of earliest appearance of modern mammals and subsequent dispersal to the Holarctic continents.

  10. Late Paleocene-early Eocene carbon isotope stratigraphy from a near-terrestrial tropical section and antiquity of Indian mammals

    Science.gov (United States)

    Samanta, A.; Sarkar, A.; Bera, M. K.; Rai, Jyotsana; Rathore, S. S.

    2013-02-01

    Late Paleocene to early Eocene (~56 to 51 Ma) interval is characterized by five distinct transient warming (hyperthermal) events (Paleocene-Eocene thermal maximum (PETM), H1/ETM2/ELMO, H2, I1 and I2) in a super greenhouse globe associated with negative carbon isotope excursions (CIEs). Although well-documented marine records exist at different latitudes, terrestrial PETM sections are rare. In particular, almost no terrestrial records of either the PETM or early Eocene hyperthermals (EEHs) are yet available from the tropics. Further, evolution of modern order of mammals near the PETM has been recorded in many northern continents; however, the response of mammals in the tropics to these warming events is unknown. A tropical terrestrial record of these hyperthermal/CIE events, encompassing the earliest modern order mammal bearing horizon from India, can therefore be vital in understanding climatic and biotic evolution during the earliest Cenozoic time. Here, for the first time, we report high resolution carbon isotope ( δ 13C) stratigraphy, nannofossil, and Sr isotope ratio of marine fossil carbonate from the Cambay Shale Formation of Western India. The record shows complete preservation of all the above CIE events, including the PETM, hitherto unknown from the equatorial terrestrial records. δ 13C chemostratigraphy further suggests that at least the present early Eocene mammal-bearing horizon, recently discovered at Vastan, does not support the `out of India' hypothesis of earliest appearance of modern mammals and subsequent dispersal to the Holarctic continents.

  11. Assessment Analysis and Forecasting for Security Early Warning of Energy Consumption Carbon Emissions in Hebei Province, China

    Directory of Open Access Journals (Sweden)

    Yi Liang

    2017-03-01

    Full Text Available Against the backdrop of increasingly serious global climate change and the development of the low-carbon economy, the coordination between energy consumption carbon emissions (ECCE and regional population, resources, environment, economy and society has become an important subject. In this paper, the research focuses on the security early warning of ECCE in Hebei Province, China. First, an assessment index system of the security early warning of ECCE is constructed based on the pressure-state-response (P-S-R model. Then, the variance method and linearity weighted method are used to calculate the security early warning index of ECCE. From the two dimensions of time series and spatial pattern, the security early warning conditions of ECCE are analyzed in depth. Finally, with the assessment analysis of the data from 2000 to 2014, the prediction of the security early warning of carbon emissions from 2015 to 2020 is given, using a back propagation neural network based on a kidney-inspired algorithm (KA-BPNN model. The results indicate that: (1 from 2000 to 2014, the security comprehensive index of ECCE demonstrates a fluctuating upward trend in general and the trend of the alarm level is “Severe warning”–“Moderate warning”–“Slight warning”; (2 there is a big spatial difference in the security of ECCE, with relatively high-security alarm level in the north while it is relatively low in the other areas; (3 the security index shows the trend of continuing improvement from 2015 to 2020, however the security level will remain in the state of “Semi-secure” for a long time and the corresponding alarm is still in the state of “Slight warning”, reflecting that the situation is still not optimistic.

  12. Placement Supervision of Pedagogue Students in Denmark: The Role of University Colleges and Early Childhood Centres

    Science.gov (United States)

    Jensen, Jytte Juul

    2015-01-01

    The article examines Danish pedagogue students' supervision during their placement periods in early childhood settings. Throughout the long history of Danish pedagogue education, discourses relating to the placement element have been located either within a "work" paradigm or a "scholastic" paradigm. These two understandings of…

  13. The emergence and early development of prosocial behavior: universalities and cultural specifications

    NARCIS (Netherlands)

    Song, Y.; Dubas, J.J.S.; Broekhuizen, M.L.

    2015-01-01

    Despite a long standing interest in the early development of prosocial behaviors, there is still considerable controversy about their origins and development. While some researchers propose that humans are born with a fundamental motivation to help, share and comfort others (nature), some

  14. An extensive catalogue of early-type galaxies in the nearby universe

    CERN Document Server

    Dabringhausen, J

    2016-01-01

    We present a catalogue of 1715 early-type galaxies from the literature, spanning the luminosity range from faint dwarf spheroidal galaxies to giant elliptical galaxies. The aim of this catalogue is to be one of the most comprehensive and publicly available collections of data on early-type galaxies. The emphasis in this catalogue lies on dwarf elliptical galaxies, for which some samples with detailed data have been published recently. For almost all of the early-type galaxies included in it, this catalogue contains data on their locations, distances, redshifts, half-light radii, the masses of their stellar populations and apparent magnitudes in various passbands. Data on metallicity and various colours are available for a majority of the galaxies presented here, including many of the rather faint early-type galaxies in the Local group. The data on magnitudes, colours, metallicities and masses of the stellar populations is supplemented with entries that are based on fits to data from simple stellar population ...

  15. Carbonate chemistry in sediment porewaters of the Rhône River delta driven by early diagenesis (northwestern Mediterranean)

    Science.gov (United States)

    Rassmann, Jens; Lansard, Bruno; Pozzato, Lara; Rabouille, Christophe

    2016-09-01

    The Rhône River is the largest source of terrestrial organic and inorganic carbon for the Mediterranean Sea. A large fraction of this terrestrial carbon is either buried or mineralized in the sediments close to the river mouth. This mineralization follows aerobic and anaerobic pathways, with a range of impacts on calcium carbonate precipitation and dissolution in the sediment near the sediment-water interface. This study focuses on the production of dissolved inorganic carbon (DIC) and total alkalinity (TA) by early diagenesis, consequential pH variations and the effect on calcium carbonate precipitation or dissolution. The sediment porewater chemistry was investigated along a transect from the Rhône River outlet to the continental shelf. TA and concentrations of DIC, SO42- and Ca2+ were analyzed on bottom waters and extracted sediment porewaters, whereas pH and oxygen concentrations were measured in situ using microelectrodes. The average oxygen penetration depth into the sediment was 1.7 ± 0.4 mm close to the river mouth and 8.2 ± 2.6 mm in the continental shelf sediments, indicating intense respiration rates. Diffusive oxygen fluxes through the sediment-water interface ranged between 3 and 13 mmol O2 m-2 d-1. In the first 30 cm of the sediment, TA and DIC porewater concentrations increased with depth up to 48 mmol L-1 near the river outlet and up to 7 mmol L-1 on the shelf as a result of aerobic and anaerobic mineralization processes. Due to aerobic processes, at all stations pH decreased by 0.6 pH units in the oxic layer of the sediment accompanied by a decrease of the saturation state regarding calcium carbonate. In the anoxic layer of the sediments, sulfate reduction was the dominant mineralization process and was associated with an increase of porewater saturation state regarding calcium carbonate. Ultimately anoxic mineralization of organic matter caused calcium carbonate precipitation demonstrated by a large decrease in Ca2+ concentration with depth in

  16. An expeditious synthesis of early transition metal carbide nanoparticles on graphitic carbons.

    Science.gov (United States)

    Ressnig, Debora; Moldovan, Simona; Ersen, Ovidiu; Beaunier, Patricia; Portehault, David; Sanchez, Clément; Carenco, Sophie

    2016-08-01

    An expeditious synthesis of metal carbide nanoparticles onto various carbon supports is demonstrated. The procedure is versatile and readily yields TiC, VC, Mo2C and W2C nanoparticles on different types of carbons. The reaction is initiated at room temperature and proceeds within seconds. This novel synthetic route paves the way for a large variety of metal carbide-carbon nanocomposites that may be implemented in emerging nanotechnology fields.

  17. Wave function of the Universe in the early stage of its evolution

    CERN Document Server

    Maydanyuk, Sergei P

    2007-01-01

    In quantum cosmological models, constructed in the Friedmann-Robertson-Walker metrics, a nucleation of Universe with its further extension is described as a tunneling transition (or leaving out) of wave through effective barrier between regions with small and large values of scale factor a at nonzero (or zero) energy. An approach for description of tunneling with leaving outside consists in construction of wave function under choice of needed boundary condition. There are different ways for definition of the boundary condition that leads to different estimations of barrier penetrability and duration of the Universe nucleation. In given paper, with a purpose to describe a process of leaving of the wave from the tunneling region outside accurately as possible, to construct the total wave function on the basis of its two partial solutions unambiguously, the tunneling boundary condition (the total wave function must represent only the wave outgoing outside) is used at point of the wave leaving from the barrier ou...

  18. Was The Electromagnetic Spectrum A Blackbody Spectrum In The Early Universe?

    OpenAIRE

    Opher, Merav; Opher,Reuven

    1997-01-01

    It is assumed, in general, that the electromagnetic spectrum in the Primordial Universe was a blackbody spectrum in vacuum. We derive the electromagnetic spectrum, based on the Fluctuation-Dissipation Theorem that describes the electromagnetic fluctuations in a plasma. Our description includes thermal and collisional effects in a plasma. The electromagnetic spectrum obtained differs from the blackbody spectrum in vacuum at low frequencies. In particular, concentrating on the primordial nucleo...

  19. Assessing the Observability of Hypernovae and Pair-Instability Supernovae in the Early Universe

    CERN Document Server

    Wiggins, Brandon K; Whalen, Daniel J; Even, Wesley P; Migenes, Victor; Fryer, Chris L

    2015-01-01

    The era of the universe's first (Population III) stars is essentially unconstrained by observation. Ultra-luminous and massive stars from this time altered the chemistry of the cosmos, provided the radiative scaffolding to support the formation of the first protogalaxies, and facilitated the creation and growth of now-supermassive black holes. Unfortunately, because these stars lie literally at the edge of the observable universe, they will remain beyond the reach of even the next generation of telescopes such as the James Webb Space Telescope and the Thirty-Meter Telescope. In this paper, we provide a primer to supernovae modeling and the first stars to make our discussion accessible to those new to or outside our field. We review recent work of the Los Alamos Supernova Light Curve Project and Brigham Young University to explore the possibility of probing this era through observations of the spectacular deaths of the first stars. We find that many such brilliant supernova explosions will be observable as far...

  20. [Universal screening program and early intervention (USPEI) in congenital bilateral sensorineural hearing loss in Chile].

    Science.gov (United States)

    Albertz, Nicolás; Cardemil, Felipe; Rahal, Maritza; Mansilla, Francisca; Cárdenas, Rodrigo; Zitko, Pedro

    2013-08-01

    Congenital hearing loss is the total or partial inability to hear sounds through the ears. It is the most common disability in newborns in Chile and worldwide, and is a permanent condition. The direct impact on children who are not adequately diagnosed is the alteration in acquisition of language and cognitive skills and a decline in their social and school insertion, jeopardizing their professional and potentially productive life. Universal screening programs for hearing loss are essential for the diagnosis, since 50% of infants with hearing loss have no known risk factor. Screening before one month of age, confirmation before 3 months, and effective intervention before 6 months, allows the development of these children as if they had normal hearing. In Chile there is a selective program of screening for infants aged less than 32 weeks or 1,500 grams, as part of Explicit Health Guarantees, but it covers only 0.9% of newborns per year. Therefore, a large majority of children remain without diagnosis. The aim of this review is to compare the situation in Chile with other countries, raising the need to move towards a universal neonatal hearing loss screening program, and propose necessary conditions in terms of justification and implementation of a universal screening public policy.

  1. Record of Early Toarcian carbon cycle perturbations in a nearshore environment: the Bascharage section (easternmost Paris Basin)

    Science.gov (United States)

    Hermoso, M.; Delsate, D.; Baudin, F.; Le Callonnec, L.; Minoletti, F.; Renard, M.; Faber, A.

    2014-04-01

    In order to understand the significance of worldwide deposition of black shale facies in the Early Toarcian (~ 183 Ma), considerable attention has been drawn to this Early Jurassic sub-Stage over the last three decades. The discovery of a pronounced negative carbon isotope excursion (CIE) within the black shales disrupting the generally positive trend in carbon isotopes has stimulated many studies, particularly with a view to establish the local vs. global nature of this major geochemical phenomenon. Here we document the sedimentological and chemostratigraphic evolution of a proximal environment in the Luxembourgian sedimentary area, the so-called Gutland. At Bascharage, Lower Toarcian sediments record the isotopic signature of the Early Toarcian Oceanic Anoxic Event (OAE) by a pronounced positive trend that testifies for widespread anoxia. The expression of the carbon isotope perturbation in this section however, is unusual compared to adjacent NW European sections. A first -7 ‰ negative CIE, whose onset is recorded at the top of the tenuicostatum zone, can be assigned to the well-documented and potentially global T-CIE with confidence using the well-constrained ammonite biostratigraphic framework for this section. In this interval, facies contain only a limited amount of carbonate as a result of intense detrital supply in such a proximal and shallow environment. Stratigraphically higher in the section, the serpentinum zone records a subsequent CIE (-6 ‰) that is expressed by four negative steps, each being accompanied by positive shifts in the oxygen isotopic composition of carbonate. The preservation state of coccoliths and calcareous dinoflagellates in the second CIE is excellent and comparable to that observed in under- and overlying strata, so this cannot be an artefact of diagenesis. Considering the nature of this record, and the lack of such a pronounced event in the serpentinum zone in coeval sections in Europe, we hypothesise that this second CIE was

  2. Combined oxygen- and carbon-isotope records through the Early Jurassic: multiple global events and two modes of carbon-cycle/temperature coupling

    DEFF Research Database (Denmark)

    Hesselbo, Stephen P.; Korte, Christoph

    2010-01-01

    The Jurassic comprises some 55 million years of Earth history. However, within the Jurassic, only one major environmental change (hyperthermal) event is really well known - the Early Toarcian Oceanic Anoxic Event (OAE) at ~183 Ma - and until very recently the extent to which the accompanying...... environmental changes were global has been strongly debated. Nevertheless, partly as a result of the international effort to define Global Stratotype Sections and Points (GSSPs), much more is now being discovered about environmental changes taking place at and around the other Jurassic Age (Stage) boundaries......, to the extent that meaningful comparisons between these events can begin to be made. Here we present new carbon and oxygen isotope data from mollusks (bivalves and belemnites) and brachiopods collected through the marine Early Jurassic succession of NE England, including the Sinemurian-Plienbachian boundary...

  3. ACCURATE TIME-DEPENDENT WAVE PACKET STUDY OF THE H{sup +}+LiH REACTION AT EARLY UNIVERSE CONDITIONS

    Energy Technology Data Exchange (ETDEWEB)

    Aslan, E.; Bulut, N. [Department of Physics, Firat University, 23169 Elazig (Turkey); Castillo, J. F.; Banares, L.; Aoiz, F. J. [Departamento de Quimica Fisica I, Facultad de Ciencias Quimicas (Unidad Asociada CSIC), Universidad Complutense de Madrid, 28040 Madrid (Spain); Roncero, O., E-mail: jfernand@quim.ucm.es [Instituto de Fisica Fundamental, CSIC, C/Serrano 123, E-28006 Madrid (Spain)

    2012-11-01

    The dynamics and kinetics of the H{sup +} + LiH reaction have been studied using a quantum reactive time-dependent wave packet (TDWP) coupled-channel quantum mechanical method on an ab initio potential energy surface at conditions of the early universe. The total reaction probabilities for the H{sup +} + LiH(v = 0, j = 0) {yields} H{sup +} {sub 2} + Li process have been calculated from 5 Multiplication-Sign 10{sup -3} eV up to 1 eV for total angular momenta J from 0 to 110. Using a Langevin model, integral cross sections have been calculated in that range of collision energies and extrapolated for energies below 5 Multiplication-Sign 10{sup -3} eV. The calculated rate constants are found to be nearly independent of temperature in the 10-1000 K interval with a value of Almost-Equal-To 10{sup -9} cm{sup 3} s{sup -1}, which is in good agreement with estimates used in evolutionary models of the early universe lithium chemistry.

  4. Post-recombination early Universe cooling by translation-internal inter-conversion: The role of minor constituents.

    Science.gov (United States)

    McCaffery, Anthony J

    2015-09-14

    Little is known of the mechanism by which H and H2, the principal constituents of the post-re-combination early Universe, cooled sufficiently to permit cluster formation, nucleosynthesis, and, eventually, the formation of structured objects. Radiative decay primarily cools the internal modes of H2, as Δj = - 2 jumps accompany quadrupolar emission. This, however, would be a self-limiting mechanism. In this work, a translational energy cooling mechanism based on collision-induced, translation-to-internal mode conversion, is extended, following an earlier study [A. J. McCaffery and R. J. Marsh, J. Chem. Phys. 139, 234310 (2013)] of ensembles comprising H2 in a H atom bath gas. Here, the possible influence of minor species, such as HD, on this cooling mechanism is investigated. Results suggest that the influence of HD is small but not insignificant. Conversion is very rapid and an overall translation-to-internal energy conversion efficiency of some 5% could be expected. This finding may be of use in the further development of models of this complex phase of early Universe evolution. An unexpected finding in this study was that H2 + HD ensembles are capable of very rapid translation-to-internal conversion with efficiencies of >40% and relaxation rates that appear to be relatively slow. This may have potential as an energy storage mechanism.

  5. Post-recombination early Universe cooling by translation–internal inter-conversion: The role of minor constituents

    Energy Technology Data Exchange (ETDEWEB)

    McCaffery, Anthony J., E-mail: A.J.McCaffery@sussex.ac.uk [Department of Chemistry, University of Sussex, Brighton, BN1 9QJ Sussex (United Kingdom)

    2015-09-14

    Little is known of the mechanism by which H and H{sub 2}, the principal constituents of the post-re-combination early Universe, cooled sufficiently to permit cluster formation, nucleosynthesis, and, eventually, the formation of structured objects. Radiative decay primarily cools the internal modes of H{sub 2}, as Δj = − 2 jumps accompany quadrupolar emission. This, however, would be a self-limiting mechanism. In this work, a translational energy cooling mechanism based on collision-induced, translation-to-internal mode conversion, is extended, following an earlier study [A. J. McCaffery and R. J. Marsh, J. Chem. Phys. 139, 234310 (2013)] of ensembles comprising H{sub 2} in a H atom bath gas. Here, the possible influence of minor species, such as HD, on this cooling mechanism is investigated. Results suggest that the influence of HD is small but not insignificant. Conversion is very rapid and an overall translation-to-internal energy conversion efficiency of some 5% could be expected. This finding may be of use in the further development of models of this complex phase of early Universe evolution. An unexpected finding in this study was that H{sub 2} + HD ensembles are capable of very rapid translation-to-internal conversion with efficiencies of >40% and relaxation rates that appear to be relatively slow. This may have potential as an energy storage mechanism.

  6. Universal Breast Cancer Antigens as Targets Linking Early Detection and Therapeutic Vaccination

    Science.gov (United States)

    2008-09-01

    CYP1B1 ), each overexpressed in >90% of invasive breast cancers but rarely found in normal tissue -- may fill this gap. Such targets, if found at...hTERT and CYP1B1 provide an opportunity for both early detection and cancer vaccination. Objective/Hypothesis: We hypothesize that immunologic responses...in ductal lavage fluid from BRCA1 and BRCA2 mutation carriers The last year has been spent studying genetic polymorphisms in BRCA1 and BRCA2

  7. Conductance of Sidewall-Functionalized Carbon Nanotubes: Universal Dependence on Adsorption Sites

    DEFF Research Database (Denmark)

    García-Lastra, J.M.; Thygesen, Kristian Sommer; Strange, Mikkel

    2008-01-01

    We use density functional theory to study the effect of molecular adsorbates on the conductance of metallic carbon nanotubes (CNT). The five molecules considered (NO2, NH2, H, COOH, OH) lead to very similar scattering of the electrons. The adsorption of a single molecule suppresses one of the two...

  8. A Second Higgs Doublet in the Early Universe: Baryogenesis and Gravitational Waves

    CERN Document Server

    Dorsch, G C; Konstandin, T; No, J M

    2016-01-01

    We show that simple Two Higgs Doublet models still provide a viable explanation for the matter-antimatter asymmetry of the Universe via electroweak baryogenesis, even after taking into account the recent order-of-magnitude improvement on the electron-EDM experimental bound by the ACME Collaboration. Moreover we show that, in the region of parameter space where baryogenesis is possible, the gravitational wave spectrum generated at the end of the electroweak phase transition is within the sensitivity reach of the future space-based interferometer LISA.

  9. Gone with the heat: a fundamental constraint on the imaging of dust and molecular gas in the early Universe.

    Science.gov (United States)

    Zhang, Zhi-Yu; Papadopoulos, Padelis P; Ivison, R J; Galametz, Maud; Smith, M W L; Xilouris, Emmanuel M

    2016-06-01

    Images of dust continuum and carbon monoxide (CO) line emission are powerful tools for deducing structural characteristics of galaxies, such as disc sizes, H2 gas velocity fields and enclosed H2 and dynamical masses. We report on a fundamental constraint set by the cosmic microwave background (CMB) on the observed structural and dynamical characteristics of galaxies, as deduced from dust continuum and CO-line imaging at high redshifts. As the CMB temperature rises in the distant Universe, the ensuing thermal equilibrium between the CMB and the cold dust and H2 gas progressively erases all spatial and spectral contrasts between their brightness distributions and the CMB. For high-redshift galaxies, this strongly biases the recoverable H2 gas and dust mass distributions, scale lengths, gas velocity fields and dynamical mass estimates. This limitation is unique to millimetre/submillimetre wavelengths and unlike its known effect on the global dust continuum and molecular line emission of galaxies, it cannot be addressed simply. We nevertheless identify a unique signature of CMB-affected continuum brightness distributions, namely an increasing rather than diminishing contrast between such brightness distributions and the CMB when the cold dust in distant galaxies is imaged at frequencies beyond the Raleigh-Jeans limit. For the molecular gas tracers, the same effect makes the atomic carbon lines maintain a larger contrast than the CO lines against the CMB.

  10. Implementation of quality management in early stages of research and development projects at a university.

    Science.gov (United States)

    Fiehe, Sandra; Wagner, Georg; Schlanstein, Peter; Rosefort, Christiane; Kopp, Rüdger; Bensberg, Ralf; Knipp, Peter; Schmitz-Rode, Thomas; Steinseifer, Ulrich; Arens, Jutta

    2014-04-01

    The ultimate objective of university research and development projects is usually to create knowledge, but also to successfully transfer results to industry for subsequent marketing. We hypothesized that the university technology transfer requires efficient measures to improve this important step. Besides good scientific practice, foresighted and industry-specific adapted documentation of research processes in terms of a quality management system might improve the technology transfer. In order to bridge the gap between research institute and cooperating industry, a model project has been accompanied by a project specific amount of quality management. However, such a system had to remain manageable and must not constrain the researchers' creativity. Moreover, topics and research team are strongly interdisciplinary, which entails difficulties regarding communication because of different perspectives and terminology. In parallel to the technical work of the model project, an adaptable quality management system with a quality manual, defined procedures, and forms and documents accompanying the research, development and validation was implemented. After process acquisition and analysis the appropriate amount of management for the model project was identified by a self-developed rating system considering project characteristics like size, innovation, stakeholders, interdisciplinarity, etc. Employees were trained according to their needs. The management was supported and the technical documentation was optimized. Finally, the quality management system has been transferred successfully to further projects.

  11. [The early years of anatomy and obstetrics at the Göttingen University, 1734-1760].

    Science.gov (United States)

    Rab, Irén

    2014-03-16

    In the Age of Enlightenment medical education was based on new fundamentals. According to experts at that time, a medical faculty had to have five branches: anatomy, botany, chemistry, practical and theoretical medicine. Perhaps Göttingen was the most successful university foundation at that time, because a generous financial support was provided, outstanding professors were invited and an education without censorship was warranted. The spirit of Enlightenment affected both the structure and the standards of education of the facultas medicinae. The word-wide reputation of this faculty was earned by Albrecht von Haller. Haller conceived both the still highly regarded botanical garden and the anatomical theatre, which was the first of its kind in the German speaking area. Furthermore, he founded one of the first clinical obstetrics departments in the world. Students gained theoretical knowledge, were trained practically and had the opportunity to make scientific observations and medical experiments. This paper describes the founding era of the medical faculty of University of Göttingen from a historical-cultural view of point, based on contemporary documents from Germany and Hungary.

  12. Abundance Profiling of Extremely Metal-Poor Stars and Supernova Properties in the Early Universe

    CERN Document Server

    Tominaga, Nozomu; Nomoto, Ken'ichi

    2013-01-01

    The first metal enrichment in the universe was made by a supernova (SN) explosion of a population (Pop) III star and chemical evolution of the universe is recorded in abundance patterns of extremely metal-poor (EMP) stars. Increasing number of the EMP stars are now being discovered. This allows us to statistically constrain properties of SNe of Pop III stars (Pop III SNe). We investigate the properties of Pop III SNe by comparing their nucleosynthetic yields with the abundance patterns of the EMP stars. We focus on the most metal-poor stars with [Fe/H] $\\lsim-3.5$ and present Pop III SN models that reproduce well their individual abundance patterns. From these models we derive relations between abundance ratios and properties of Pop III SNe: [(C+N)/Fe] vs. an ejected Fe mass, and [(C+N)/Mg] vs. a remnant mass. Using fitting formulae, distribution of the abundance ratios of EMP stars is converted to those of the properties of Pop III SNe, which can be compared with SNe in the present day. Large samples of EMP ...

  13. The Case of the Lacking Carbonates and the Emergence of Early Life on Mars

    Directory of Open Access Journals (Sweden)

    Ricardo Amils

    2010-08-01

    Full Text Available The mineralogical characterization of Mars by different exploration missions, provides a new image of the earliest conditions that prevailed on the planet surface. The detection of extensive deposits of phyllosillicates has been considered to be as a result of the production of hydrated silicates through alteration and precipitation under neutral to sub-alkaline conditions. Although extensive deposits of carbonates should precipitate beneath a thick CO2-bearing atmosphere, only a few outcrops of Mg-rich carbonates have been detected on Mars. Paradoxically those carbonates occur in association with geological units exposed to acidic paleoenvironments. Given such geochemical conditions on Earth, the carbon cycle is intimately associated with life, then, we can assume that the presence or absence of microbial communities should have impacted the distribution of those carbonate compounds on Mars. In this paper, we suggest three potential geobiological scenarios to explain how the emergence of life on Mars would have impacted the carbon cycle and, hence, the formation of carbonates on a planetary scale.

  14. Middle-Upper Ordovician (Darriwilian-Early Katian) Positive Carbon Isotope Excursions in the Northern Tarim Basin, Northwest China:Implications for Stratigraphic Correlation and Paleoclimate

    Institute of Scientific and Technical Information of China (English)

    Cunge Liu; Guorong Li; Dawei Wang; Yongli Liu; Mingxia Luo; Xiaoming Shao

    2016-01-01

    ABSTRACT:Three positive carbon isotope excursions are reported from Middle–Upper Ordovician in Tahe oil-gas field, northern Tarim Basin. Based on conodont biostratigraphy, the Middle Darriwilian Isotope Carbon Excursion (MDICE) and the Guttenberg Carbon Isotope Excursion (GICE) are identified from Darriwilian to Early Katian by the aid of whole-rock carbon isotope data from two well cores. Positive excursion within conodont Pygodus anserinus zone is developed in Early Sandbian, and the fluctuation range is no less than MDICE. Because the range of this excursion in the generalized global carbon isotope curve is short, previous studies paid little attention to it, and named Early Sandbian Isotope Carbon Excursion (ESICE) in this paper. Furthermore, these positive excursions are not directly related to sea level fluctuations and the MDICE and GICE identified in northern Tarim can be globally correlated to that in southern China, North America, South America, and Europe. The Saergan Fm. source rocks of Middle-Upper Ordovician in Kalpin Dawangou outcrop are in accord with the geologic time of MDICE and ESICE, and GICE have strong ties to the source rock of Lianglitag Fm. in basin. Abundant organic carbon burial is an important factor in genesis of positive isotope carbon excursions. Positive oxygen isotope excursion, conodont fauna turnover, decreased conodont total diversity, and the change of sedimentary facies indicated that dramatic changes of paleoceanographic environment of Early-Middle Ordovician in Tarim Basin started from the end of Darriwillian, and an obvious icehouse climate of Late Ordovician occurred in ESICE.

  15. Universal crossover of the charge carrier fluctuation mechanism in different polymer/carbon nanotubes composites

    Energy Technology Data Exchange (ETDEWEB)

    Barone, C., E-mail: cbarone@unisa.it; Mauro, C.; Pagano, S. [Dipartimento di Fisica “E.R. Caianiello” and CNR-SPIN Salerno, Università di Salerno, I-84084 Fisciano, Salerno (Italy); Landi, G.; Neitzert, H. C. [Dipartimento di Ingegneria Industriale, Università di Salerno, I-84084 Fisciano, Salerno (Italy)

    2015-10-05

    Carbon nanotubes added to polymer and epoxy matrices are compounds of interest for applications in electronics and aerospace. The realization of high-performance devices based on these materials can profit from the investigation of their electric noise properties, as this gives a more detailed insight of the basic charge carriers transport mechanisms at work. The dc and electrical noise characteristics of different polymer/carbon nanotubes composites have been analyzed from 10 to 300 K. The results suggest that all these systems can be regarded as random resistive networks of tunnel junctions formed by adjacent carbon nanotubes. However, in the high-temperature regime, contributions deriving from other possible mechanisms cannot be separated using dc information alone. A transition from a fluctuation-induced tunneling process to a thermally activated regime is instead revealed by electric noise spectroscopy. In particular, a crossover is found from a two-level tunneling mechanism, operating at low temperatures, to resistance fluctuations of a percolative network, in the high-temperature region. The observed behavior of 1/f noise seems to be a general feature for highly conductive samples, independent on the type of polymer matrix and on the nanotube density.

  16. Entropy in the Present and Early Universe: New Small Parameters and Dark Energy Problem

    Directory of Open Access Journals (Sweden)

    Alexander Shalyt-Margolin

    2010-04-01

    Full Text Available It is demonstrated that entropy and its density play a significant role in solving the problem of the vacuum energy density (cosmological constant of the Universe and hence the dark energy problem. Taking this in mind, two most popular models for dark energy—Holographic Dark Energy Model and Agegraphic Dark Energy Model—are analysed. It is shown that the fundamental quantities in the first of these models may be expressed in terms of a new small dimensionless parameter that is naturally occurring in High Energy Gravitational Thermodynamics and Gravitational Holography (UV-limit. On this basis, the possibility of a new approach to the problem of Quantum Gravity is discussed. Besides, the results obtained on the uncertainty relation of the pair “cosmological constant–volume of space-time”, where the cosmological constant is a dynamic quantity, are reconsidered and generalized up to the Generalized Uncertainty Relation.

  17. AMAZE and LSD: Metallicity and Dynamical Evolution of Galaxies in the Early Universe

    Science.gov (United States)

    Maiolino, R.; Mannucci, F.; Cresci, G.; Gnerucci, A.; Troncoso, P.; Marconi, A.; Calura, F.; Cimatti, A.; Cocchia, F.; Fontana, A.; Granato, G.; Grazian, A.; Matteucci, F.; Nagao, T.; Pentericci, L.; Pipino, A.; Pozzetti, L.; Risaliti, G.; Silva, L.

    2010-12-01

    The metal content in galaxies provides important information on the physical processes responsible for galaxy formation, but little was known for galaxies at z > 3, when the Universe was less than 15% of its current age. We report on our metallicity survey of galaxies at z > 3 using SINFONI at the VLT. We find that at z > 3, low-mass galaxies obey the same fundamental relation between metallicity, mass and star formation rate as at 0 3 massive galaxies deviate from this relation, being more metal-poor. In some of these massive galaxies we can even map the gas metallicity. We find that galaxies at z > 3.3 have regular rotation, though highly turbulent, and inverted abundance gradients relative to local galaxies, with lower abundances near the centre, close to the most active regions of star formation. Overall the results suggest that prominent inflow of pristine gas is responsible for the strong chemical evolution observed in galaxies at z > 3.

  18. First look at a major transition period in the early Universe

    Science.gov (United States)

    1997-08-01

    In recent years astronomers have successfully `looked back' towards this period, but the new observations of HE 2347-4342 have now homed in on an important transitionary epoch during the evolution of the young Universe. Searching for clear views towards bright quasars As has been the case for many other important scientific achievements, this observational breakthrough was preceded by a long and tedious period of careful preparatory work. It began in 1989, when Dieter Reimers and his collaborators from the University of Hamburg (Germany) initiated a spectral survey of the entire southern sky with the 1-metre ESO Schmidt Telescope at La Silla. The aim was to find bright quasars, a rare class of remote galaxies with unusually bright and energetic centres. They would then be studied in greater detail with other, larger telescopes. For this programme, a large objective prism is placed in front of the telescope, allowing the simultaneous recording on a large photographic plate of spectra of about 40,000 celestial objects in a 5o x 5o sky field. The plates are sent to Hamburg where they are scanned (digitized) in a microphotometer and automatically searched for spectra of quasars. Until now, more than 400 plates have been obtained. One of the main goals of this vast programme is to find bright and distant quasars, in particular those whose light reaches us along relatively unobstructed paths. Or, in other words, those intrinsically bright and remote quasars which are located in directions where the Universe is unusually transparent for ultraviolet light. With a 'clear view' thus ensured, it would subsequently be possible to study such far-away objects and the intergalactic gas out there in unprecedented detail with large telescopes. The greater the distance, the longer has the light been underway, the longer is the 'look-back' time and the earlier is the epoch about which we then obtain new information. Discovery of a unique quasar Altogether, more than 650 bright

  19. Relation Between Early Maladaptive Schemes and Anxiety and Depression Features in University Students

    Directory of Open Access Journals (Sweden)

    Diana Lucía Sánchez-Ortíz***

    2009-12-01

    Full Text Available Anxiety and depression are important health problems, because of the high prevalence rates in normal population and in clinical population. This non-experimental study intends to identify the cognitive profile, through the early maladaptive schemes in students from the Universidad Pontificia Bolivariana Bucaramanga, related with depression and anxiety scores. Thegoal is to contribute to the identification of cognitive characteristics that could help in the prevention of these disorders. 259 psychology students of the first seven semesters were evaluated by means from the following questionnaires: BDI, ST/DEP, STAI and YSQ-L2. The results don’t show the presence of specific schemes as a function of the presence of State/ Trait depression or State/Trait anxiety, which might suggest, through the dimensional paradigm, the presence of a cognitive pattern for an anxiety and depression mix disorder. It is suggested that further research should be carried out with other samples, including clinical population.

  20. Thermal Relics in Modified Cosmologies: Bounds on Evolution Histories of the Early Universe and Cosmological Boosts for PAMELA

    CERN Document Server

    Catena, R; Pato, M; Pieri, L; Masiero, A

    2010-01-01

    Alternative cosmologies, based on extensions of General Relativity, predict modified thermal histories in the Early Universe in the pre Big Bang Nucleosynthesis (BBN) era, epoch which is not directly constrained by cosmological observations. When the expansion rate is enhanced with respect to the standard case, thermal relics typically decouple with larger relic abundances. The correct value of the relic abundance is therefore obtained for larger annihilation cross sections, as compared to standard cosmology. A direct consequence is that indirect detection rates are enhanced. Extending previous analyses of ours, we derive updated astrophysical bounds on the dark matter annihilation cross sections and use them to constrain alternative cosmologies in the pre-BBN era. We also determine the characteristics of these alternative cosmologies in order to provide the correct value of relic abundance for a thermal relic for the (large) annihilation cross section required to explain the PAMELA results on the positron fr...

  1. Non-equilibrium H$_2$ formation in the early Universe: energy exchanges, rate coefficients and spectral distortions

    CERN Document Server

    Coppola, Carla Maria; Galli, Daniele; Tennyson, Jonathan; Longo, Savino

    2012-01-01

    Energy exchange processes play a crucial role in the early Universe, affecting the thermal balance and the dynamical evolution of the primordial gas. In the present work we focus on the consequences of a non-thermal distribution of the level populations of H$_2$: first, we determine the excitation temperatures of vibrational transitions and the non-equilibrium heat transfer; second, we compare the modifications to chemical reaction rate coefficients with respect to the values obtained assuming local thermodynamic equilibrium; third, we compute the spectral distortions to the cosmic background radiation generated by the formation of H$_2$ in vibrationally excited levels. We conclude that non-equilibrium processes cannot be ignored in cosmological simulations of the evolution of baryons, although their observational signatures remain below current limits of detection. New fits to the equilibrium and non-equilibrium heat transfer functions are provided.

  2. The characteristic black hole mass resulting from direct collapse in the early universe

    CERN Document Server

    Latif, M A; Schmidt, W; Niemeyer, J C

    2013-01-01

    Black holes of a billion solar masses are observed in the infant universe a few hundred million years after the Big Bang. The direct collapse of protogalactic gas clouds in primordial halos with $\\rm T_{vir} \\geq 10^{4} K$ provides the most promising way to assemble massive black holes. In this study, we aim to determine the characteristic mass scale of seed black holes and the time evolution of the accretion rates resulting from the direct collapse model. We explore the formation of supermassive black holes via cosmological large eddy simulations (LES) by employing sink particles and following their evolution for twenty thousand years after the formation of the first sink. As the resulting protostars were shown to have cool atmospheres in the presence of strong accretion, we assume here that UV feedback is negligible during this calculation. We confirm this result in a comparison run without sinks. Our findings show that black hole seeds with characteristic mass of $\\rm 10^{5} M_{\\odot}$ are formed in the pr...

  3. The characteristic black hole mass resulting from direct collapse in the early Universe

    Science.gov (United States)

    Latif, M. A.; Schleicher, D. R. G.; Schmidt, W.; Niemeyer, J. C.

    2013-12-01

    Black holes of a billion solar masses are observed in the infant Universe a few hundred million years after the big bang. The direct collapse of protogalactic gas clouds in primordial haloes with Tvir ≥ 104 K provides the most promising way to assemble massive black holes. In this study, we aim to determine the characteristic mass scale of seed black holes and the time evolution of the accretion rates resulting from the direct collapse model. We explore the formation of supermassive black holes via cosmological large eddy simulations (LES) by employing sink particles and following their evolution for 20 000 yr after the formation of the first sink. As the resulting protostars were shown to have cool atmospheres in the presence of strong accretion, we assume here that UV feedback is negligible during this calculation. We confirm this result in a comparison run without sinks. Our findings show that black hole seeds with characteristic mass of 105 M⊙ are formed in the presence of strong Lyman-Werner flux which leads to an isothermal collapse. The characteristic mass is about two times higher in LES compared to the implicit large eddy simulations. The accretion rates increase with time and reach a maximum value of 10 M⊙ yr-1 after 104 yr. Our results show that the direct collapse model is clearly feasible as it provides the expected mass of the seed black holes.

  4. Introducing CoDa (Cosmic Dawn): Radiation-Hydrodynamics of Galaxy Formation in the Early Universe

    Science.gov (United States)

    Ocvirk, Pierre; Gillet, Nicolas; Shapiro, Paul; Aubert, Dominique; Iliev, Ilian; Romain, Teyssier; Yepes, Gustavo; Choi, Jun-hwan; Sullivan, David; Knebe, Alexander; Gottloeber, Stefan; D'Aloisio, Anson; Park, Hyunbae; Hoffman, Yehuda

    2015-08-01

    CoDa (Cosmic Dawn) is the largest fully coupled radiation hydrodynamics simulation of the reionization of the local Universe to date. It was performed using RAMSES-CUDATON running on 8192 nodes (i.e. 8192 GPUs) on the titan supercomputer at Oak Ridge National Laboratory to simulate a 64 h-1Mpc side box down to z=4.23. In this simulation, reionization proceeds self-consistently, driven by stellar radiation. We compare the simulation's reionization history, ionizing flux density, the cosmic star formation history and the CMB Thompson scattering optical depth with their observational values. Luminosity functions are also in rather good agreement with high redshift observations, although very bright objects (MAB1600 gas filaments present a sheathed structure, with a hot envelope surrounding a cooler core. They are however not able to self-shield, while regions denser than 10^-4.5 H atoms per comoving h^-3cm^3 are. Haloes below M ˜ 3.10^9 M⊙ are severely affected by the expanding, rising UV background: their ISM is quickly photo-heated to temperatures above our star formation threshold and therefore stop forming stars after local reionization has occured. Overall, the haloes between 10^(10-11) M⊙ dominate the star formation budget of the box for most of the Epoch of Reionization. Several additional studies will follow, looking for instance at environmental effects on galaxy properties, and the regimes of accretion.

  5. High Redshift Radio Galaxies: Laboratories for Massive Galaxy and Cluster Formation in the early Universe

    CERN Document Server

    Miley, G; Taylor, G B; De Breuck, C; Cohen, A

    2009-01-01

    High redshift radio galaxies are among the largest, most luminous, most massive, and most beautiful objects in the Universe. They are generally identified from their radio emission, thought to be powered by accretion of matter onto supermassive black holes in the nuclei of their host galaxies. Observations show that they are energetic sources of radiation throughout most of the electromagnetic spectrum, including relativistic plasma, gas and dust, stars and the active galactic nuclei (AGN). 1 HzRGs are inferred to be extremely massive, including old stars (up to $\\sim$ 10$^{12}$ M$_{\\odot}$), hot gas (up to $\\sim$ 10$^{12}$ M$_{\\odot}$) and molecular gas (up to $\\sim$ 10$^{11}$ M$_{\\odot}$).Because they are highly luminous and (unlike quasars) spatially resolvable from the ground, most components of HzRGs provide important diagnostic information about the spatial distributions of processes within HzRGs and their environment. The fact that the different constituents are present in the same objects and that the...

  6. Black hole growth in the early Universe is self-regulated and largely hidden from view

    CERN Document Server

    Treister, Ezequiel; Volonteri, Marta; Natarajan, Priyamvada; Gawiser, Eric

    2011-01-01

    The formation of the first massive objects in the infant Universe remains impossible to observe directly and yet it sets the stage for the subsequent evolution of galaxies. While some black holes with masses > billion solar masses? have been detected in luminous quasars less than one billion years after the Big Bang, these individual extreme objects have limited utility in constraining the channels of formation of the earliest black holes. The initial conditions of black hole seed properties are quickly erased during the growth process. From deep, optimally stacked, archival X-ray observations, we measure the amount of black hole growth in z=6-8 galaxies (0.7-1 billion years after the Big Bang). Our results imply that black holes grow in tandem with their hosts throughout cosmic history, starting from the earliest times. We find that most copiously accreting black holes at these epochs are buried in significant amounts of gas and dust that absorb most radiation except for the highest energy X-rays. This sugge...

  7. Non-thermal photons and H2 formation in the early Universe

    CERN Document Server

    Coppola, Carla Maria; Palla, Francesco; Longo, Savino; Chluba, Jens

    2013-01-01

    The cosmological recombination of H and He at z \\sim 1000 and the formation of H2 during the dark ages produce a non-thermal photon excess in the Wien tail of the cosmic microwave background (CMB) blackbody spectrum. Here we compute the effect of these photons on the H- photodetachment and H2+ photodissociation processes. We discuss the implications for the chemical evolution of the Universe in the post-recombination epoch, emphasizing how important a detailed account of the full vibrational manifold of H2 and H2+ in the chemical network is. We find that the final abundances of H2, H2+, H3+ and HD are significantly smaller than in previous calculations that neglected the effect of non-thermal photons. The suppression is mainly caused by extra hydrogen recombination photons and could affect the formation rate of first stars. We provide simple analytical approximations for the relevant rate coefficients and briefly discuss the additional effect of dark matter annihilation on the considered reaction rates.

  8. ["Die grosse Barb" in the museum of the University of Marburg. An early documentation of acromegaly].

    Science.gov (United States)

    Krause, W; Rassner, G; Happle, R

    2009-06-01

    The university museum for cultural history in the castle of Marburg has a portrait "Die grosse Barb", which represents a women suffering from acromegaly. She shows the typical pathologic alterations: thickening of the skin folds, thickening of the lips and the eyelids, growth of bones and cartilages, lengthening of the nose, enlargement of the ears, protrusion of the zygoma, mandible and the chin. Acromegaly is a consequence of enhanced secretion of growth hormone, which occurs also as a symptom of several syndromes, such as multiple endocrine neoplasia type 1, McCune-Albright-syndrome, and NAME syndrome (Carney complex type I). The most remarkable symptom of acromegaly is the gigantism. This occurs also in androgen-deficient states, such as the Klinefelter syndrome and some more genetic syndromes, of which the Simpson-Golabi-Behmel syndrome, the Sotos syndrome, the Marfan syndrome, the homocystinuria, and the fragile X-syndrome may be mentioned. Nothing is known on the further fate of the patient shown in the portrait. It is also unknown, whether she owes her position as a chambermaid to her gigantism, for it was a common use in courts to have people with abnormal body shapes in attendance.

  9. Early gas stripping as the origin of the darkest galaxies in the Universe.

    Science.gov (United States)

    Mayer, L; Kazantzidis, S; Mastropietro, C; Wadsley, J

    2007-02-15

    The known galaxies most dominated by dark matter (Draco, Ursa Minor and Andromeda IX) are satellites of the Milky Way and the Andromeda galaxies. They are members of a class of faint galaxies, devoid of gas, known as dwarf spheroidals, and have by far the highest ratio of dark to luminous matter. None of the models proposed to unravel their origin can simultaneously explain their exceptional dark matter content and their proximity to a much larger galaxy. Here we report simulations showing that the progenitors of these galaxies were probably gas-dominated dwarf galaxies that became satellites of a larger galaxy earlier than the other dwarf spheroidals. We find that a combination of tidal shocks and ram pressure swept away the entire gas content of such progenitors about ten billion years ago because heating by the cosmic ultraviolet background kept the gas loosely bound: a tiny stellar component embedded in a relatively massive dark halo survived until today. All luminous galaxies should be surrounded by a few extremely dark-matter-dominated dwarf spheroidal satellites, and these should have the shortest orbital periods among dwarf spheroidals because they were accreted early.

  10. The impact of ionizing radiation on the formation of a supermassive star in the early Universe

    CERN Document Server

    Chon, Sunmyon

    2016-01-01

    A massive primordial halo near an intensely star forming galaxy may collapse into a supermassive star (SMS) and leave a massive black hole seed of about $10^5~M_{sun}$. To investigate the impact of ionizing radiation on the formation of an SMS from a nearby galaxy, we perform three-dimensional radiation hydrodynamical simulations by selecting a pair of massive dark matter halos forming at $z >10$. We find that rich structures such as clumps and filaments around the source galaxy shield the cloud from ionizing radiation. In fact, in some cases cloud collapse is accelerated under ionizing radiation. This fact suggests that the ionization of the cloud's surroundings helps its collapse. Only strong radiation at the early stage of structure formation can halt the cloud collapse, but this is much stronger than observationally allowed value. We also explored the effect of ionizing radiation on a sample of 68 halos by employing an analytical model and found that increase in the mean density of the gas between the SMS...

  11. Early Gas Stripping as the Origin of the Darkest Galaxies in the Universe

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Lucio; /Zurich, ETH /Zurich U.; Kazantzidis, Stelios; /KIPAC, Menlo Park /KICP, Chicago; Mastropietro, Chiara; /Munich U. Observ.; Wadsley, James; /McMaster U.

    2007-02-28

    The known galaxies most dominated by dark matter (Draco, Ursa Minor and Andromeda IX) are satellites of the Milky Way and the Andromeda galaxies. They are members of a class of faint galaxies, devoid of gas, known as dwarf spheroidals, and have by far the highest ratio of dark to luminous matter. None of the models proposed to unravel their origin can simultaneously explain their exceptional dark matter content and their proximity to a much larger galaxy. Here we report simulations showing that the progenitors of these galaxies were probably gas-dominated dwarf galaxies that became satellites of a larger galaxy earlier than the other dwarf spheroidals. We find that a combination of tidal shocks and ram pressure swept away the entire gas content of such progenitors about ten billion years ago because heating by the cosmic ultraviolet background kept the gas loosely bound: a tiny stellar component embedded in a relatively massive dark halo survived until today. All luminous galaxies should be surrounded by a few extremely dark-matter-dominated dwarf spheroidal satellites, and these should have the shortest orbital periods among dwarf spheroidals because they were accreted early.

  12. Initiating an Action Research Programme for University EFL Teachers: Early Experiences and Responses

    Directory of Open Access Journals (Sweden)

    Anne Burns

    2016-10-01

    Full Text Available Accounts of how teacher educators begin to plan, develop, and support action research programmes for language teachers are rare, as are descriptions of the responses of the teachers who participate. This article documents and analyses the initial processes of introducing and supporting a new programme of action research for language teachers at the Universidad Chileno-Británica de Cultura (UCBC in Santiago, Chile. To evaluate the setting up of the programme and how the teachers have perceived it in its early stages, the authors, who are the programme facilitators, have conducted a meta- study. Data include workshop and meeting recordings, workshop observation notes, a reflective account, and a teacher questionnaire. The findings indicate that the teachers value the input and collaboration provided by an initial workshop, and subsequent meetings and discussions, very highly, but that issues of time, student involvement, and academic literature are areas for further debate and development. The article ends by drawing out the broader implications for UCBC and for others wishing to initiate similar action research programmes.

  13. Carbon-Enhanced Metal-Poor Stars in the Early Galaxy

    CERN Document Server

    Marsteller, B; Rossi, S; Christlieb, N; Bessell, M; Rhee, J

    2004-01-01

    Very metal-deficient stars that exhibit enhancements of their carbon abundances are of crucial importance for understanding a number of issues -- the nature of stellar evolution among the first generations of stars, the shape of the Initial Mass Function, and the relationship between carbon enhancement and neutron-capture processes, in particular the astrophysical s-process. One recent discovery from objective-prism surveys dedicated to the discovery of metal-deficient stars is that the frequency of Carbon-Enhanced Metal-Poor (CEMP) stars increases with declining metallicity, reaching roughly 25% for [Fe/H] < -2.5. In order to explore this phenomenon in greater detail we have obtained medium-resolution (2 A) spectroscopy for about 350 of the 413 objects in the Christlieb et al. catalog of carbon-rich stars, selected from the Hamburg/ESO objective prism survey on the basis of their carbon-enhancement, rather than metal deficiency. Based on these spectra, and near-IR JHK photometry from the 2MASS Point Sourc...

  14. Dynamical 3-Space Predicts Hotter Early Universe: Resolves CMB-BBN 7-Li and 4-He Abundance Anomalies

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2010-01-01

    Full Text Available The observed abundances of 7-Li and 4-He are significantly inconsistent with the predictions from Big Bang Nucleosynthesis (BBN when using the $Lambda$CDM cosmological model together with the value for $Omega_B h^2 = 0.0224pm0.0009$ from WMAP CMB fluctuations, with the value from BBN required to fit observed abundances being $0.009 < Omega_B h^2 < 0.013$. The dynamical 3-space theory is shown to predict a 20% hotter universe in the radiation-dominated epoch, which then results in a remarkable parameter-free agreement between the BBN and the WMAP value for $Omega_B h^2$. The dynamical 3-space also gives a parameter-free fit to the supernova redshift data, and predicts that the flawed $Lambda$CDM model would require $Omega_Lambda = 0.73$ and $Omega_M = 0.27$ to fit the 3-space dynamics Hubble expansion, and independently of the supernova data. These results amount to the discovery of new physics for the early universe that is matched by numerous other successful observational and experimental tests.

  15. Dynamical 3-Space Predicts Hotter Early Universe: Resolves CMB-BBN 7-Li and 4-He Abundance Anomalies

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2010-01-01

    Full Text Available The observed abundances of 7 Li and 4 He are significantly inconsistent with the pre- dictions from Big Bang Nucleosynthesis (BBN when using the CDM cosmolog- ical model together with the value for B h 2 = 0 : 0224 0 : 0009 from WMAP CMB fluctuations, with the value from BBN required to fit observed abundances being 0 : 009 < B h 2 < 0 : 013. The dynamical 3-space theory is shown to predict a 20% hot- ter universe in the radiation-dominated epoch, which then results in a remarkable parameter-free agreement between the BBN and the WMAP value for B h 2 . The dy- namical 3-space also gives a parameter-free fit to the supernova redshift data, and pre- dicts that the flawed CDM model would require = 0 : 73 and M = 0 : 27 to fit the 3-space dynamics Hubble expansion, and independently of the supernova data. These results amount to the discovery of new physics for the early universe that is matched by numerous other successful observational and experimental tests.

  16. Teaching Universal Design in the Early Stages of a Design Curriculum: Involving End Users in a Student Project.

    Science.gov (United States)

    Wilson, Wendell; Choi, Young Mi; Jones, Brian

    2016-01-01

    Introducing Universal Design (UD) early in the design curriculum provides design students with a basic foundational understanding of the Universal Design principles and processes. Additionally, by guiding students on the application of the UD principles and process in designing a solution to a real-world need, students experienced the challenges and tradeoffs such design requires. In Spring 2016, teams of Sophomore-level Industrial Design students were assigned an educational exercise to solve a real-world problem of barriers experienced by people with disabilities during grocery shopping. Students employed the UD process in designing a shopping device enhanced with mobile/wireless enabled features that would be usable by a wide range of users. The shopping device had to function effectively and meet the needs of the general public (men, women, tall, short, etc) while simultaneously meeting the needs of users who have other physical and perceptual limitations such as mobility limitations and visual impairments. In this paper, we discuss the key steps of the educational exercise, as well as lessons learned for improving the exercise for future courses.

  17. Evidence for carbon flux shortage and strong carbon/nitrogen interactions in pea nodules at early stages of water stress.

    Science.gov (United States)

    Gálvez, Loli; González, Esther M; Arrese-Igor, Cesar

    2005-09-01

    Symbiotic N2 fixation in legume nodules declines under a wide range of environmental stresses. A high correlation between N2 fixation decline and sucrose synthase (SS; EC 2.4.1.13) activity down-regulation has been reported, although it has still to be elucidated whether a causal relationship between SS activity down-regulation and N2 fixation decline can be established. In order to study the likely C/N interactions within nodules and the effects on N2 fixation, pea plants (Pisum sativum L. cv. Sugar snap) were subjected to progressive water stress by withholding irrigation. Under these conditions, nodule SS activity declined concomitantly with apparent nitrogenase activity. The levels of UDP-glucose, glucose-1-phosphate, glucose-6-phosphate, and fructose-6-phosphate decreased in water-stressed nodules compared with unstressed nodules. Drought also had a marked effect on nodule concentrations of malate, succinate, and alpha-ketoglutarate. Moreover, a general decline in nodule adenylate content was detected. NADP+-dependent isocitrate dehydrogenase (ICDH; EC 1.1.1.42) was the only enzyme whose activity increased as a result of water deficit, compensating for a possible C/N imbalance and/or supplying NADPH in circumstances that the pentose phosphate pathway was impaired, as suggested by the decline in glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) activity. The overall results show the occurrence of strong C/N interactions in nodules subjected to water stress and support a likely limitation of carbon flux that might be involved in the decline of N2 fixation under drought.

  18. Two superluminous supernovae from the early universe discovered by the supernova legacy survey

    Energy Technology Data Exchange (ETDEWEB)

    Howell, D. A. [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93117 (United States); Kasen, D. [Departments of Physics and Astronomy, University of California, Berkeley, Berkeley, CA 94720-7300 (United States); Lidman, C. [Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia); Sullivan, M. [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Conley, A. [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309-389 (United States); Astier, P.; Balland, C.; Guy, J.; Hardin, D.; Pain, R.; Regnault, N. [LPNHE, CNRS-IN2P3 and University of Paris VI and VII, F-75005 Paris (France); Carlberg, R. G. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H8 (Canada); Fouchez, D. [CPPM, CNRS-IN2P3 and University Aix Marseille II, Case 907, F-13288 Marseille Cedex 9 (France); Palanque-Delabrouille, N.; Rich, J.; Ruhlmann-Kleider, V. [DSM/IRFU/SPP, CEA-Saclay, F-91191 Gif-sur-Yvette (France); Perrett, K. [DRDC Ottawa, 3701 Carling Avenue, Ottawa, ON K1A 0Z4 (Canada); Pritchet, C. J. [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Victoria, BC V8W 3P6 (Canada)

    2013-12-20

    We present spectra and light curves of SNLS 06D4eu and SNLS 07D2bv, two hydrogen-free superluminous supernovae (SNe) discovered by the Supernova Legacy Survey. At z = 1.588, SNLS 06D4eu is the highest redshift superluminous SN with a spectrum, at M{sub U} = –22.7 it is one of the most luminous SNe ever observed, and it gives a rare glimpse into the rest-frame ultraviolet where these SNe put out their peak energy. SNLS 07D2bv does not have a host galaxy redshift, but on the basis of the SN spectrum, we estimate it to be at z ∼ 1.5. Both SNe have similar observer-frame griz light curves, which map to rest-frame light curves in the U band and UV, rising in ∼20 rest-frame days or longer and declining over a similar timescale. The light curves peak in the shortest wavelengths first, consistent with an expanding blackbody starting near 15,000 K and steadily declining in temperature. We compare the spectra with theoretical models, and we identify lines of C II, C III, Fe III, and Mg II in the spectra of SNLS 06D4eu and SCP 06F6 and find that they are consistent with an expanding explosion of only a few solar masses of carbon, oxygen, and other trace metals. Thus, the progenitors appear to be related to those suspected for SNe Ic. A high kinetic energy, 10{sup 52} erg, is also favored. Normal mechanisms of powering core-collapse or thermonuclear SNe do not seem to work for these SNe. We consider models powered by {sup 56}Ni decay and interaction with circumstellar material, but we find that the creation and spin-down of a magnetar with a period of 2 ms, a magnetic field of 2 × 10{sup 14} G, and a 3 M {sub ☉} progenitor provides the best fit to the data.

  19. Description and Early Outcomes of a Comprehensive Curriculum Redesign at the Northwestern University Feinberg School of Medicine.

    Science.gov (United States)

    Heiman, Heather L; O'Brien, Celia L; Curry, Raymond H; Green, Marianne M; Baker, James F; Kushner, Robert F; Thomas, John X; Corbridge, Thomas C; Corcoran, Julia F; Hauser, Joshua M; Garcia, Patricia M

    2017-09-26

    In 2012, the Northwestern University Feinberg School of Medicine launched a redesigned curriculum addressing the four primary recommendations in the 2010 Carnegie Foundation for the Advancement of Teaching report on reforming medical education. This new curriculum provides a more standardized evaluation of students' competency achievement through a robust portfolio review process coupled with standard evaluations of medical knowledge and clinical skills. It individualizes learning processes through curriculum flexibility, enabling students to take electives earlier and complete clerkships in their preferred order. The new curriculum is integrated both horizontally and vertically, combining disciplines within organ-based modules and deliberately linking elements (science in medicine, clinical medicine, health and society, professional development) and threads (medical decision making, quality and safety, teamwork and leadership, lifestyle medicine, advocacy and equity) across the three phases that replaced the traditional four-year timeline. It encourages students to conduct research in an area of interest and commit to lifelong learning and self-improvement. The curriculum formalizes the process of professional identity formation and requires students to reflect on their experiences with the informal and hidden curricula, which strongly shape their identities.The authors describe the new curriculum structure, explain their approach to each Carnegie report recommendation, describe early outcomes and challenges, and propose areas for further work. Early data from the first cohort to progress through the curriculum show unchanged United States Medical Licensing Examination Step 1 and 2 scores, enhanced student research engagement and career exploration, and improved student confidence in the patient care and professional development domains.

  20. Shell-model study of boron, carbon, nitrogen and oxygen isotopes based on monopole-based-universal interaction

    CERN Document Server

    Yuan, Cenxi; Otsuka, Takaharu; Xu, Furong; Tsunoda, Naofumi; 10.1103/PhysRevC.85.064324

    2012-01-01

    We study boron, carbon, nitrogen and oxygen isotopes with a newly constructed shell-model Hamiltonian developed from monopole-based-universal interaction ($V_{MU}$). The present Hamiltonian can reproduce well the ground-state energies, energy levels, electric quadrupole properties and spin properties of these nuclei in full psd model space including $(0-3)\\hbar\\omega$ excitations. Especially, it correctly describes the drip lines of carbon and oxygen isotopes and the spins of the ground states of $^{10}$B and $^{18}$N while some former interactions such as WBP and WBT fail. We point out that the inclusion of $2\\hbar\\omega$ excitations is important in reproducing some of these properties. In the present $(0+2)\\hbar\\omega$ calculations small but constant E2 effective charges appear to work quite well. As the inclusion of the $2\\hbar\\omega$ model space makes rather minor change, this seems to be related to the smallness of $^{4}$He core. Similarly, the spin g factors are very close to free values. The applicabil...

  1. Nursing habits and early childhood caries in children attending Hospital University Science Malaysia (HUSM

    Directory of Open Access Journals (Sweden)

    Widowati Witjaksono

    2006-06-01

    Full Text Available The habit of nocturnal bottle or breast-feeding has been reported to be a potential cause for early childhood caries (ECC in very young children. The aim of this study was to determine the prevalence of ECC in children 2-5 years of age attending out patient clinic HUSM, in relation to the nursing habits. In this cross-sectional study, 90 children were randomly selected to examine their caries status using torch and disposable mirror. Data on mothers’ educational level, nursing habits and oral hygiene practices, were gather by using structured questionnaire. It has been found that 16.7% of subjects were caries free while 83.3% of them had caries with mean dmf score 6 (SD 5.3. With regard to nursing habits, 29% of subjects had breast-feeding alone, 16% had bottle-feeding alone and 55% had both breast and bottle-feeding. Ninety-three percent of children had been nursed beyond 14 months and 47% had been fed with liquids other than breast milk, infant formula or water. Twenty-seven percent of children were allowed to sleep with nursing bottle in mouth and 52% were allowed to sleep with breast nipple in the mouth which shows significantly associated with ECC (p = 0.03. Tooth brushing habit was reported for 91% of children using toothpaste. Mean age of the children (in months when the mothers started brushing the teeth was 19.1 (SD 10.8 and has significant association with ECC (p < 0.05. This study demonstrates that the habit of allowing infants to sleep with breast nipple in their mouth and the late start of tooth brushing are associated with prevalence of ECC. Educational programs for pregnant women and mothers of young children should be emphasized to enhance the knowledge and awareness of mothers in preventing ECC.

  2. Early Biomarkers in 1H Nuclear Magnetic Resonance Spectroscopy of Striatal Pathological Mechanisms after Acute Carbon Monoxide Poisoning in Rats

    Institute of Scientific and Technical Information of China (English)

    GUAN Li; LI Zong Yang; ZHANG Yan Lin; CONG Cui Cui; ZHAO Jin Yuan

    2015-01-01

    Objective In vivo Proton Magnetic Resonance Spectroscopy (1H-MRS) can be used to evaluate the levels of specific neurochemical biomarkers of pathological mechanisms in the brain. Methods We conducted T2-Weighted Magnetic Resonance Imaging (MRI) and 1H-MRS with a 3.0-Tesla animal MRI system to investigate the early microstructural and metabolic profiles in vivo in the striatum of rats following carbon monoxide (CO) poisoning. Results Compared to baseline, we found significant cortical surface deformation, cerebral edema changes, which were indicated by the unclear gray/white matter border, and lateral ventricular volume changes in the brain. A significant reduction in the metabolite to total creatine (Cr) ratios of N-acetylaspartate (NAA) was observed as early as 1 h after the last CO administration, while the lactate (Lac) levels increased marginally. Both the Lac/Cr and NAA/Cr ratios leveled off at 6 h and showed no subsequent significant changes. In addition, compared to the control, the choline (Cho)/Cr ratio was slightly reduced in the early stages and significantly increased after 6 h. In addition, a pathological examination revealed mild cerebral edema on cessation of the insult and more severe cerebral injury after additional CO poisoning. Conclusion The present study demonstrated that 1H-MRS of the brain identified early metabolic changes after CO poisoning. Notably, the relationship between the increased Cho/Cr ratio in the striatum and delayed neuropsychologic sequelae requires further research.

  3. A universal scheme to convert aromatic molecular monolayers into functional carbon nanomembranes.

    Science.gov (United States)

    Angelova, Polina; Vieker, Henning; Weber, Nils-Eike; Matei, Dan; Reimer, Oliver; Meier, Isabella; Kurasch, Simon; Biskupek, Johannes; Lorbach, Dominik; Wunderlich, Katrin; Chen, Long; Terfort, Andreas; Klapper, Markus; Müllen, Klaus; Kaiser, Ute; Gölzhäuser, Armin; Turchanin, Andrey

    2013-08-27

    Free-standing nanomembranes with molecular or atomic thickness are currently explored for separation technologies, electronics, and sensing. Their engineering with well-defined structural and functional properties is a challenge for materials research. Here we present a broadly applicable scheme to create mechanically stable carbon nanomembranes (CNMs) with a thickness of ~0.5 to ~3 nm. Monolayers of polyaromatic molecules (oligophenyls, hexaphenylbenzene, and polycyclic aromatic hydrocarbons) were assembled and exposed to electrons that cross-link them into CNMs; subsequent pyrolysis converts the CNMs into graphene sheets. In this transformation the thickness, porosity, and surface functionality of the nanomembranes are determined by the monolayers, and structural and functional features are passed on from the molecules through their monolayers to the CNMs and finally on to the graphene. Our procedure is scalable to large areas and allows the engineering of ultrathin nanomembranes by controlling the composition and structure of precursor molecules and their monolayers.

  4. Climate Cycling on Early Mars Caused by the Carbonate-Silicate Cycle

    CERN Document Server

    Batalha, Natasha E; Haqq-Misra, Jacob; Kasting, James F

    2016-01-01

    For decades, scientists have tried to explain the evidence for fluvial activity on early Mars, but a consensus has yet to emerge regarding the mechanism for producing it. One hypothesis suggests early Mars was warmed by a thick greenhouse atmosphere. Another suggests that early Mars was generally cold but was warmed occasionally by impacts or by episodes of enhanced volcanism. These latter hypotheses struggle to produce the amounts of rainfall needed to form the martian valleys, but are consistent with inferred low rates of weathering compared to Earth. Here, we provide a geophysical mechanism that could have induced cycles of glaciation and deglaciation on early Mars. Our model produces dramatic climate cycles with extended periods of glaciation punctuated by warm periods lasting up to 10 Myr, much longer than those generated in other episodic warming models. The cycles occur because stellar insolation was low, and because CO2 outgassing is not able to keep pace with CO2 consumption by silicate weathering fo...

  5. Low-Energy Mutual Neutralization Studies for Early Universe Hydrogen Chemistry

    Science.gov (United States)

    Urbain, Xavier

    2010-03-01

    Low-energy interactions between light ions, as they occur in low density plasmas, are ideally studied under merged-beam conditions. This was the motivation for building the dual-source setup in operation at UCL, Louvain-la-Neuve, since the early eighties. Although initially developed for the study of charge exchange [1], mutual neutralization and transfer ionization, this machine has produced a host of total cross section measurements for a wide variety of associative ionization and other reactive processes involving charged reactants, from H^+ to CO^+, in collision with H^-, D^-, C^- and O^- [2]. A recent paper by Glover et al. [3] has revived the interest for mutual neutralization studies, by stressing the need of the astrophysical community for a precise determination of the low-energy cross section of the H^+/H^- reaction. The mutual neutralization acts as a sink for negative ions which otherwise dominate the primordial formation of H2 by associative detachment with ground state H. Absolute measurements in the range 5 meV to 5 eV are needed to rule out earlier experimental work [4] contradicting the most recent theoretical predictions [5]. Our setup is currently modified to incorporate coincident imaging techniques, giving access to differential cross sections besides the branching among accessible neutral channels. Mutual neutralization reactions of H^- with H2^+ and H3^+ will also be investigated, for the role they play in laboratory plasmas [6].[4pt] [1] S. Sz"ucs, M. Karemera, M. Terao, and F. Brouillard, J. Phys. B 17, 1613 (1983).[0pt] [2] E. A. Naji et al., J. Phys. B 31, 4887 (1998), A. Le Padellec et al., J. Chem. Phys., 124, 154304 (2006) and references therein.[0pt] [3] S. C. Glover, D. W. Savin, and A.-K. Jappsen , Astrophys. J. 640, 553 (2006). [0pt] [4] J. Moseley, W. Aberth, and J. R. Peterson, Phys. Rev. Lett. 24, 435 (1970).[0pt] [5] M. Stenrup, å. Larson, and N. Elander, Phys. Rev. A 79, 012713 (2009).[0pt] [6] M. J. J. Eerden et al., Phys

  6. Recognition of Early Eocene global carbon isotope excursions using lipids of marine Thaumarchaeota

    NARCIS (Netherlands)

    Schoon, P.L.; Heilmann-Clausen, C.; Schultz, B.P.; Sluijs, A.; Sinninghe Damsté, J.S.; Schouten, S.

    2013-01-01

    The Paleocene-Eocene Thermal Maximum (PETM; similar to 56 Ma) and Eocene Thermal Maximum 2 (ETM2; similar to 53 Ma) are geological short (<200,000 years) episodes of extreme global warming and environmental change. Both the PETM and ETM2 are associated with the injection of C-13-depleted carbon into

  7. Recognition of Early Eocene global carbon isotope excursions using lipids of marine Thaumarchaeota

    NARCIS (Netherlands)

    Schoon, P.L.; Heilmann-Clausen, C.; Pagh Schultz, B.; Sluijs, A.; Sinninghe Damsté, J.S.; Schouten, S.

    2013-01-01

    The Paleocene–Eocene Thermal Maximum (PETM; ∼56 Ma) and Eocene Thermal Maximum 2 (ETM2; ∼53 Ma) are geological short (<200,000 years) episodes of extreme global warming and environmental change. Both the PETM and ETM2 are associated with the injection of 13C-depleted carbon into the ocean–atmosphere

  8. Early Precambrian Carbonate and Evapolite Sediments: Constraints on Environmental and Biological Evolution

    Science.gov (United States)

    Grotzinger, John P.

    2002-01-01

    The work accomplished under NASA Grant NAG5-6722 was very successful. Our lab was able to document the occurrence and distribution of evaporite-to-carbonate transitions in several basins during Precambrian time, to help constrain the long-term chemical evolution of seawater.

  9. Unravelling uncertainty and variability in early stage techno-economic assessments of carbon capture technologies

    NARCIS (Netherlands)

    van der Spek, Mijndert; Sanchez Fernandez, Eva; Eldrup, Nils Henrik; Skagestad, Ragnhild; Ramirez, Andrea; Faaij, André

    2017-01-01

    This paper addresses the uncertainty and variability in techno-economic studies of carbon capture technologies, based on a detailed comparison of the results of different studies on postcombustion CO2 capture with advanced amines, and on an in-depth uncertainty analysis using a combination of sensit

  10. Carbon and Water Flux Observations from AmeriFlux and Fluxnet: Some Early Results

    Science.gov (United States)

    Law, B. E.

    2001-12-01

    Flux networks provide a means for scientists to make common measurements of carbon, water, and energy exchange, to share advancements in methods, and synthesize results across the network. AmeriFlux objectives are to: Determine how environmental factors and climate regulate ecosystem CO2 and H2O exchange over the short- and long-term, evaluate impacts of anthropogenic factors, and provide data and new understanding for incorporation into models. AmeriFlux is part of the larger international network, Fluxnet. Among Fluxnet sites, we investigated seasonal and annual CO2 and water vapor exchange, and relations with environmental variables to elucidate generalities within and among biomes. The data showed a strong linkage between carbon gain and water loss, with the highest water-use efficiency values for grasslands, and lowest values for tundra. Ecosystem respiration was only weakly correlated with mean annual temperature across biomes, in spite of sensitivity within site over shorter temporal scales. Mean annual temperature and site water balanced explained much of the variation in gross photosynthesis, whereby water availability limits LAI over the long-term, and inter-annual climate variability limits carbon uptake below the potential of the leaf area available for photosynthesis. We compared BIOME-BGC model results among AmeriFlux coniferous forests, and the model showed that variation in net ecosystem carbon exchange (NEE) is mostly a function of disturbance history, with important secondary effects from site climate, ecophysiology, and changing atmospheric CO2 and nitrogen deposition.

  11. Recognition of Early Eocene global carbon isotope excursions using lipids of marine Thaumarchaeota

    Science.gov (United States)

    Schoon, Petra L.; Heilmann-Clausen, Claus; Pagh Schultz, Bo; Sluijs, Appy; Sinninghe Damsté, Jaap S.; Schouten, Stefan

    2013-07-01

    The Paleocene-Eocene Thermal Maximum (PETM; ˜56 Ma) and Eocene Thermal Maximum 2 (ETM2; ˜53 Ma) are geological short (CIE) and massive dissolution of deep sea carbonate. However, the magnitude of these CIEs vary with the type of fossil matter, i.e. multiple carbonate phases, bulk organic matter, and terrestrial and marine biomarker lipids, making it difficult to constrain the actual CIE in atmospheric and oceanic carbon pools. Here we analyzed the stable carbon isotopic composition (δ13C) of glycerol dibiphytanyl glycerol tetraether lipids (GDGTs) derived from marine Thaumarchaeota in sediments deposited during the PETM in the North Sea Basin and ETM2 in the Arctic Ocean. The δ13C values of these lipids are potentially directly recording variations in δ13C dissolved inorganic carbon (DIC) and can thus provide a record of marine δ13C DIC across both these Eocene carbon cycle perturbations. Reconstructed pre-CIE δ13CDIC values are slightly lower (0.5-1‰) than modern day values, possibly because Thaumarchaeotal lipids are not only derived from surface waters but also from 13C-depleted subsurface waters. Their values decrease by ˜3.6 (±0.3) ‰ and ˜2.5 (±0.7)‰ during the PETM and ETM2, respectively. The CIE in crenarchaeol for ETM2 is higher than that in marine calcite from other locations, possibly because of the admixture of deep water 13C-depleted CO2 generated by the euxinic conditions that developed occasionally during ETM2. However, the reconstructed PETM CIE lies close to the CIE inferred from marine calcite, suggesting that the δ13C record of crenarchaeol may document changes in marine DIC during the PETM in the North Sea Basin. The δ13C of thaumarchaeotal lipids may thus be a novel tool to reconstruct the δ13C of DIC in sediments that are devoid of carbonates, but relatively rich in organic matter, such as shallow marine coastal settings.

  12. Early stages of carbonate mineralization revealed from molecular simulations: Implications for biomineral formation

    Science.gov (United States)

    Wallace, A. F.; DeYoreo, J.; Banfield, J. F.

    2011-12-01

    The carbonate mineral constituents of many biomineralized products, formed both in and ex vivo, grow by a multi-stage crystallization process that involves the nucleation and structural reorganization of transient amorphous phases. The existence of transient phases and cluster species has significant implications for carbonate nucleation and growth in natural and engineered environments, both modern and ancient. The structure of these intermediate phases remains elusive, as does the nature of the disorder to order transition, however, these process details may strongly influence the interpretation of elemental and isotopic climate proxy data obtained from authigenic and biogenic carbonates. While molecular simulations have been applied to certain aspects of crystal growth, studies of metal carbonate nucleation are strongly inhibited by the presence of kinetic traps that prevent adequate sampling of the potential landscape upon which the growing clusters reside within timescales accessible by simulation. This research addresses this challenge by marrying the recent Kawska-Zahn (KZ) approach to simulation of crystal nucleation and growth from solution with replica-exchange molecular dynamics (REMD) techniques. REMD has been used previously to enhance sampling of protein conformations that occupy energy wells that are separated by sizable thermodynamic and kinetic barriers, and is used here to probe the initial formation and onset of order within hydrated calcium and iron carbonate cluster species during nucleation. Results to date suggest that growing clusters initiate as short linear ion chains that evolve into two- and three-dimensional structures with continued growth. The planar structures exhibit an obvious 2d lattice, while establishment of a 3d lattice is hindered by incomplete ion desolvation. The formation of a dehydrated core consisting of a single carbonate ion is observed when the clusters are ~0.75 nm. At the same size a distorted, but discernible

  13. Literacy in Action: A Carbon-Neutral Field Program at Cornell University

    Science.gov (United States)

    Moore, A.; Derry, L.

    2010-12-01

    The Cornell Earth and Environmental Systems (EES) Field Program is a semester-length undergraduate field program located on the island of Hawai`i. The Hawaiian Islands are the world’s most dynamic natural laboratory and the premier location for Earth systems research and education. While there are compelling reasons for students and faculty to travel from the US mainland to Hawai`i, the air and ground travel that comprises the program carries a large carbon footprint. This liability is also an extraordinary educational opportunity. For the past two years EES students have been challenged to make the program carbon-neutral. They are asked to devise a set of criteria for a credible and defensible zero-CO2 footprint and then to put their plan into action. The C-neutral project consists of three elements: (1) quantifying CO2 emissions, (2) reducing emissions wherever possible, and (3) offsetting emissions that cannot be eliminated. In quantifying emissions six areas are identified: air travel, ground travel, domestic electricity, natural gas, food, and waste. Emissions reductions include all of the standard “carpool--turn it down--turn it off “ conservation behaviors, with special emphasis on food and waste; eating local and organic, shopping at re-use centers, and compost and recycling of garbage. Our program facility utilizes solar hot water and is equipped with neither heat nor air conditioning, thus domestic energy use is low. Students tabulate all of our energy use and calculate the resulting CO2 emissions for all program participants for a period of four months. The CO2 offsetting strategy is conducted in collaboration with a native ecosystem restoration project. Students participate in all aspects of forest restoration, including seed collection, germination and outplanting of native plant species and removal of invasive pest species. The initial goal of this locally-supported project was to restore degraded pasture to native forest. The EES students have

  14. Major early Eocene carbon cycle perturbations and changes in planktic foraminiferal assemblages from the southeast Atlantic Ocean (ODP Site 1263)

    Science.gov (United States)

    Luciani, Valeria; D'Onofrio, Roberta; Dickens, Gerald Roy; Wade, Bridget

    2017-04-01

    On a paleoclimatic perspective the early Paleogene represents one of the most interesting and dynamic intervals of the Earth's history. Present record indicates that the Earth climate system reached its Cenozoic maximum peak of global warming and probably of pCO2 during the early Eocene climatic optimum (EECO, 49-53 Ma). Superimposed to the general trend, our planet experienced short-term ( 40-200 kyr) repeated peaks in global temperatures and major changes in the carbon cycle, known as hyperthermals. Great scientific interest has been focused on the early Paleogene hyperthermal events, given the assumed similarity with the current climatic scenario. Less attention has been dedicated to the EECO long lasting perturbation of extraordinary warming thus many characters of this interval still remain largely unconstrained, especially as for the biotic response. We present here results on early Eocene planktic foraminiferal analysis from the southeast Atlantic Ocean Drilling Program (ODP) Site 1263 (Walvis Ridge, Leg 208) to explore possible relationship between changes in assemblages and carbon cycle perturbation. The time interval is of particular interest for an abrupt switch occurred at low-latitude of the northern hemisphere between two important calcifiers of the tropical-subtropical early Paleogene oceans, the genera Morozovella and Acarinina at the carbon isotopic excursion known as J event, at the EECO onset. Precisely, the relative abundance of Morozovella permanently decreased by at least half, along with a progressive decrease in the number of species. Concomitantly, Acarinina almost doubled its abundance and diversified. Site 1263 was located during the early Eocene at a latitude of 40° south therefore representing a temperate setting of southern hemisphere not yet explored for planktic foraminiferal changes. We document a permanent decrease in Morozovella abundance at the beginning of the EECO, although this decline is delayed by 165 kyr with respect to

  15. 南京大学土地利用碳排放研究进展%Research Progresses of Land Use Carbon Emission in Nanjing University

    Institute of Scientific and Technical Information of China (English)

    赵荣钦; 陈志刚; 黄贤金; 钟大洋; 揣小伟; 赖力; 张墨逸

    2012-01-01

    To explore the influences of human activities on global carbon cycle, anthropogenic carbon emission has become the major concern and a "hot spot" in academic circles. The most important anthropogenic influ- ences on climate are greenhouse gas emissions and land use changes. As the direct embodiments of industrial activities and government policies, the alteration of land use structure will change the pattern, structure of hu- man energy consumptions, and will further Change the natural and human Carbon emission intensity and affect regional carbon cycle processes and efficiency. So, the impact of human economic and energy activities on re- gional carbon cycle is largely achieved by changing the land use structure and pattern. Therefore, land use is an important aspect in the research of low-carbon economy and carbon emission, and is also one of the important tools for carbon emission regulation and control. Research on land use carbon emission is helpful to promote the developing of low-carbon economy through land use planning, industrial structure regulation and control and territorial development, renovation and management. Since 2007, depending on the Non-profit Industry Fi- nancial Program of Ministry of Land and Resources of China and National Social Science Foundation of Chi- na, based on the research background and discipline advantages in Human Geography, researches on land use carbon emission appeared in human geography discipline of Nanjing University, which was quite earlier in Chi- na. Research process of land use carbon emission in Nanjing University includes two stages: research on re- gional carbon emission estimation and its driving mechanism on different scales, and the research on carbon emission effect of land use change and its optimization and regulation and control. According to the literature review on land use carbon emission research of Nanjing University, the main directions and achievements in the past several years was summarized. The

  16. Early Cretaceous Shallow-Water Platform Carbonates of the Bolkar Mountains, Central Taurides - South Turkey: Facies Analysis and Depositional Environments

    Science.gov (United States)

    Solak, Cemile; Taslı, Kemal; Koç, Hayati

    2016-10-01

    The study area comprises southern non-metamorphic part of the Bolkar Mountains which are situated in southern Turkey, eastern part of the Central Taurides. The studied five outcrops form geologically parts of the tectonostratigraphic units called as allochthonous Aladag Unit and autochthonous Geyikdagi Unit. The aim of this study is to describe microfacies and depositional environments of the Bolkar Mountains Early Cretaceous shallow- water platform carbonates. The Lower Cretaceous is represented by continuous thick- bedded to massive dolomite sequence ranging from 100 to 150 meters thick, which only contains locally laminated limestone intercalations in the Yüğlük section and thick to very thick-bedded uniform limestones ranging from approximately 50 to 120 meters, consist of mainly laminated- fenestral mudstone, peloidal-intraclastic grainstone-packstone, bioclastic packstone- wackestone, benthic foraminiferal-intraclastic grainstone-packstone, ostracod-fenestral wackestone-mudstone, dasycladacean algal packstone-wackestone and ooidal grainstone microfacies. Based on a combination sedimantological data, facies/microfacies and micropaleontological (predominantly dasycladacean algae and diverse benthic foraminifera) analysis, it is concluded that Early Cretaceous platform carbonates of the Bolkar Mountains reflect a tidally affected tidal-flat and restricted lagoon settings. During the Berriasian- Valanginian unfavourable facies for benthic foraminifera and dolomitization were predominate. In the Hauterivian-early Aptian, the effect of dolomitization largely disappeared and inner platform conditions still prevailed showing alternations of peritidal and lagoon facies, going from peritidal plains (representing various sub-environments including supratidal, intertidal area, tidal-intertidal ponds and ooid bars) dominated by ostracod and miliolids, to dasycladacean algae-rich restricted lagoons-subtidal. These environments show a transition in the vertical and

  17. Urgonian platform carbonates (Barremian-Early Aptian) of southeastern France: description of a new project and first data

    Science.gov (United States)

    Bastide, F.; Massonnat, G.; Föllmi, K.; Adatte, T.; Dumont, T.; Arnaud-Vanneau, A.; Virgone, A.; Arnaud, H.

    2012-04-01

    Urgonian platform carbonates are widespread in southeastern France. They were deposited along the northern Tethyan margin and bordered the Vocontian basin. They are predominantly composed of rudistic wackestone and bioclastic/ooid grainstone. The Urgonian Formation in southeastern France has been studied by various authors since 1847 (A. Orbigny, A. Arnaud-Vanneau, H. Arnaud, J. Charollais, B. Clavel, W. Kilian, J.P. Masse, R. Schroeder...). The goal of this project is to complement existing observations and produce a synthesis of the development of the Urgonian platform for the whole southeastern sector of France. This will be achieved by a sedimentological, palaeontological and stratigraphical study on 54 sections and dedicated wells, i.e., 2418 thin sections or 10.5 km of sections in total, through the entire Urgonian series, from the transgressive system track of Ba3 (early late Barremian) to the highstand system track of Ap2 (early Aptian). The sections and wells are located in five main sectors of southeastern France: Gard, Ardèche, Vercors, Vaucluse and Provence. A biostratigraphic chart relevant to all five sectors has been realized in order to correlate between the sections. In addition, the geochemistry (carbon and oxygen isotopes, whole-rock and clay mineralogies, and phosphorus contents) of five key sections (one in each main sector) has been analysed to evaluate palaeoenvironmental conditions and corroborate the stratigraphic correlation throughout southeastern France. An additional study will be performed on the global and regional geotectonic constellation during the late Barremian and the early Aptian, and finally a numerical model will be developed based on the stratigraphic correlation between the sections and consistent with their palaeoenvironmental and paleaoclimatic context. With this interdisciplinary approach, we hope to be able to reconstruct and understand the development of the Urgonian platform in terms of its palaeoenvironment, palaeo

  18. Carbon cycling and net ecosystem production at an early stage of secondary succession in an abandoned coppice forest.

    Science.gov (United States)

    Ohtsuka, Toshiyuki; Shizu, Yoko; Nishiwaki, Ai; Yashiro, Yuichiro; Koizumi, Hiroshi

    2010-07-01

    Secondary mixed forests are one of the dominant forest cover types in human-dominated temperate regions. However, our understanding of how secondary succession affects carbon cycling and carbon sequestration in these ecosystems is limited. We studied carbon cycling and net ecosystem production (NEP) over 4 years (2004-2008) in a cool-temperate deciduous forest at an early stage of secondary succession (18 years after clear-cutting). Net primary production of the 18-year-old forest in this study was 5.2 tC ha(-1 )year(-1), including below-ground coarse roots; this was partitioned into 2.5 tC ha(-1 )year(-1) biomass increment, 1.6 tC ha(-1 )year(-1) foliage litter, and 1.0 tC ha(-1 )year(-1) other woody detritus. The total amount of annual soil surface CO(2) efflux was 6.8 tC ha(-1 )year(-1), which included root respiration (1.9 tC ha(-1 )year(-1)) and heterotrophic respiration (RH) from soils (4.9 tC ha(-1 )year(-1)). The 18-year forest at this study site exhibited a great increase in biomass pool as a result of considerable total tree growth and low mortality of tree stems. In contrast, the soil organic matter (SOM) pool decreased markedly (-1.6 tC ha(-1 )year(-1)), although further study of below-ground detritus production and RH of SOM decomposition is needed. This young 18-year forest was a weak carbon sink (0.9 tC ha(-1 )year(-1)) at this stage of secondary succession. The NEP of this 18-year forest is likely to increase gradually because biomass increases with tree growth and with the improvement of the SOM pool through increasing litter and dead wood production with stand development.

  19. Diffusive fractionation of carbon isotopes in γ-Fe: Experiment, models and implications for early solar system processes

    Science.gov (United States)

    Mueller, Thomas; Watson, E. Bruce; Trail, Dustin; Wiedenbeck, Michael; Van Orman, James; Hauri, Erik H.

    2014-02-01

    Carbon is an abundant element of planets and meteorites whose isotopes provide unique insights into both organic and inorganic geochemical processes. The identities of carbonaceous phases and their textural and isotopic characters shed light on dynamical processes in modern Earth systems and the evolution of the early solar system. In meteorites and their parent bodies, reduced carbon is often associated with Fe-Ni alloys, so knowledge of the mechanisms that fractionate C isotopes in such phases is crucial for deciphering the isotopic record of planetary materials. Here we present the results of a diffusion-couple experiment in which cylinders of polycrystalline Fe containing 11,500 and 150 μg/g of C were juxtaposed at 1273 K and 1.5 GPa for a duration of 36 min. Diffusion profiles of total C concentration and 13C/12C were measured by secondary ion mass spectrometry (SIMS). The elemental diffusivity extracted from the data is ˜3.0 × 10-11 m2 s-1, where 13C/12C was observed to change significantly along the diffusion profile, reflecting a higher diffusivity of 12C relative to 13C. The maximum isotopic fractionation along the diffusion profile is ˜30-40‰. The relative diffusivities (D) of the carbon isotopes can be related to their masses (M) by D/D=(C/M)β; the exponent β calculated from our data has a value of 0.225 ± 0.025. Similarly high β values for diffusion of other elements in metals have been taken as an indication of interstitial diffusion, so our results are consistent with C diffusion in Fe by an interstitial mechanism. The high β-value reported here means that significant fractionation of carbon isotopes in nature may arise via diffusion in Fe(-Ni) metal, which is an abundant component of planetary interiors and meteorites.

  20. Opportunities for early Carbon Capture, Utilisation and Storage development in China

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, D. [ECN Biomass and Energy Efficiency, Petten (Netherlands)

    2013-01-15

    The outline of the presentation shows the following elements: China CCUS (Carbon Capture, Utilisation and Storage) policy, strategy and development status; International developments in CCUS; High-purity CO2 sources and potential EOR (Enhanced Oil Recovery) locations in China; Capture routes: (a) Separation technologies/processes, (b) CO2 purity specifications, compression and after treatment, (c) CO2 transportation options, (d) Associated Cost; Potential cost-effective full-chain CCUS projects in Shaanxi; Barriers to CCUS development in Shaanxi; and Conclusions.

  1. COMPACT STELLAR BINARY ASSEMBLY IN THE FIRST NUCLEAR STAR CLUSTERS AND r-PROCESS SYNTHESIS IN THE EARLY UNIVERSE

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez-Ruiz, Enrico; MacLeod, Morgan [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Trenti, Michele [Kavli Institute for Cosmology and Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Roberts, Luke F. [TAPIR, California Institute of Technology, Pasadena, California 91125 (United States); Lee, William H.; Saladino-Rosas, Martha I. [Instituto de Astronomía, Universidad Nacional Autónoma de México, México DF 04510, México (Mexico)

    2015-04-01

    Investigations of elemental abundances in the ancient and most metal deficient stars are extremely important because they serve as tests of variable nucleosynthesis pathways and can provide critical inferences of the type of stars that lived and died before them. The presence of r-process elements in a handful of carbon-enhanced metal-poor (CEMP-r) stars, which are assumed to be closely connected to the chemical yield from the first stars, is hard to reconcile with standard neutron star mergers. Here we show that the production rate of dynamically assembled compact binaries in high-z nuclear star clusters can attain a sufficient high value to be a potential viable source of heavy r-process material in CEMP-r stars. The predicted frequency of such events in the early Galaxy, much lower than the frequency of Type II supernovae but with significantly higher mass ejected per event, can naturally lead to a high level of scatter of Eu as observed in CEMP-r stars.

  2. U.S. China Carbon Capture and Storage Development Project at West Virginia University

    Energy Technology Data Exchange (ETDEWEB)

    Fletcher, Jerald

    2013-12-31

    The original overall objective of this activity was to undertake resource evaluation and planning for CCS projects and to describe and quantify the geologic, environmental, and economic challenges to successful development of large-scale CCS in China’s coal sector. Several project execution barriers were encountered in the course of this project, most notably a project stop/delay due to funds availability/costing restrictions from the US State Department to the US Department of Energy at the end of CY2012, which halted project execution from January 2, 2013 to April 1, 2013. At the resolution of this project delay, it was communicated to the project team that the overall project period would also be reduced, from a completion date of February 28, 2014 to December 31, 2013. The net impact of all these changes was a reduction in the project period from 24 months (3/1/2012-2/28/2014) to 22 months (3/1/2012-12/31/2013), with a 3 month stop from 1/1/2013-3/31/2013. The project team endeavored to overcome these project time impacts, focusing heavily on technoeconomic modeling that would be deliverable under Task 3 (Ordos Basin Feasibility Study), and choosing to abandon the full investigation into the Demonstration Site (Task 4) due to the reduced project time. The ultimate focus of this project changed to work with the Chinese on a carbon atlas/geologic characterization, and on mechanisms for CO2 storage options from high-quality streams within China.

  3. Sulfur and strontium isotopic compositions of carbonate and evaporite rocks from the late Neoproterozoic–early Cambrian Bilara Group (Nagaur-Ganganagar Basin, India): Constraints on intrabasinal correlation and global sulfur cycle

    Digital Repository Service at National Institute of Oceanography (India)

    Mazumdar, A.; Strauss, H.

    Sulfur and strontium isotope ratios are presented for carbonate and evaporite rocks from the late Neoproterozoic and early Cambrian Bilara and Hanseran Evaporite Groups, NW India. The sulfur isotopic compositions of trace sulfate in carbonate rocks...

  4. Early experience with the da Vinci® surgical system robot in gynecological surgery at King Abdulaziz University Hospital

    Directory of Open Access Journals (Sweden)

    Sait KH

    2011-07-01

    Full Text Available Khalid H SaitObstetrics and Gynecology Department, Faculty of Medicine, Gynecology Oncology Unit, King Abdulaziz University Hospital, Jeddah, Saudi ArabiaBackground: The purpose of this study was to review our experience and the challenges of using the da Vinci® surgical system robot during gynecological surgery at King Abdulaziz University Hospital.Methods: A retrospective study was conducted to review all cases of robot-assisted gynecologic surgery performed at our institution between January 2008 and December 2010. The patients were reviewed for indications, complications, length of hospital stay, and conversion rate, as well as console and docking times.Results: Over the three-year period, we operated on 35 patients with benign or malignant conditions using the robot for a total of 62 surgical procedures. The docking times averaged seven minutes. The mean console times for simple hysterectomy, bilateral salpingo-oophorectomy, and bilateral pelvic lymphadenectomy were 125, 47, and 62 minutes, respectively. In four patients, laparoscopic procedures were converted to open procedures, giving a conversion rate of 6.5%. All of the conversions were among the first 15 procedures performed. The average hospital stay was 3 days. Complications occurred in five patients (14%, and none were directly related to the robotic system.Conclusion: Our early experience with the robot show that with proper training of the robotic team, technical difficulty with the robotic system is limited. There is definitely a learning curve that requires performance of gynecological surgical procedures using the robot.Keywords: da Vinci robot, gynecological surgery, laparoscopy

  5. Early Combination of Material Characteristics and Toxicology Is Useful in the Design of Low Toxicity Carbon Nanofiber

    Directory of Open Access Journals (Sweden)

    Tore Syversen

    2012-09-01

    Full Text Available This paper describes an approach for the early combination of material characterization and toxicology testing in order to design carbon nanofiber (CNF with low toxicity. The aim was to investigate how the adjustment of production parameters and purification procedures can result in a CNF product with low toxicity. Different CNF batches from a pilot plant were characterized with respect to physical properties (chemical composition, specific surface area, morphology, surface chemistry as well as toxicity by in vitro and in vivo tests. A description of a test battery for both material characterization and toxicity is given. The results illustrate how the adjustment of production parameters and purification, thermal treatment in particular, influence the material characterization as well as the outcome of the toxic tests. The combination of the tests early during product development is a useful and efficient approach when aiming at designing CNF with low toxicity. Early quality and safety characterization, preferably in an iterative process, is expected to be efficient and promising for this purpose. The toxicity tests applied are preliminary tests of low cost and rapid execution. For further studies, effects such as lung inflammation, fibrosis and respiratory cancer are recommended for the more in-depth studies of the mature CNF product.

  6. Aspects of Reading Acquisition; Proceedings of the Annual Hyman Blumberg Symposium on Research in Early Childhood Education (5th, Johns Hopkins University, Nov. 13-14, 1974).

    Science.gov (United States)

    Guthrie, John T., Ed.

    Papers collected in this volume were presented at the Fifth Annual Blumberg Symposium on Research in Early Childhood Education, held at Johns Hopkins University in 1974. Selections include "Alexia" (D. Frank Benson), "Young Children's Expectations for Reading" (Doris R. Entwisle), "Relations between Acquisition of…

  7. The Learning Experiences of Early-Career Indonesian Government Employees: A Case Study in Cross-Cultural Workforce Development Based in a University Environment

    Science.gov (United States)

    Elsey, Barry; Omarova, Amina; Grill, Ronald

    2016-01-01

    The research provides a selective report on the learning experiences covering a whole year of study for a double-degree Master's programme by a cohort of early-career Indonesians. They were undertaking the second half of the programme at The University of Adelaide in South Australia, and for all 18 students it was their first taste of learning in…

  8. Test Review for Preschool-Wide Evaluation Tool (PreSET) Manual: Assessing Universal Program-Wide Positive Behavior Support in Early Childhood

    Science.gov (United States)

    Rodriguez, Billie Jo

    2013-01-01

    The Preschool-Wide Evaluation Tool (PreSET; Steed & Pomerleau, 2012) is published by Paul H. Brookes Publishing Company in Baltimore, MD. The PreSET purports to measure universal and program-wide features of early childhood programs' implementation fidelity of program-wide positive behavior intervention and support (PW-PBIS) and is,…

  9. The Learning Experiences of Early-Career Indonesian Government Employees: A Case Study in Cross-Cultural Workforce Development Based in a University Environment

    Science.gov (United States)

    Elsey, Barry; Omarova, Amina; Grill, Ronald

    2016-01-01

    The research provides a selective report on the learning experiences covering a whole year of study for a double-degree Master's programme by a cohort of early-career Indonesians. They were undertaking the second half of the programme at The University of Adelaide in South Australia, and for all 18 students it was their first taste of learning in…

  10. Towards comprehensive early abortion service delivery in high income countries: insights for improving universal access to abortion in Australia.

    Science.gov (United States)

    Dawson, Angela; Bateson, Deborah; Estoesta, Jane; Sullivan, Elizabeth

    2016-10-22

    Improving access to safe abortion is an essential strategy in the provision of universal access to reproductive health care. Australians are largely supportive of the provision of abortion and its decriminalization. However, the lack of data and the complex legal and service delivery situation impacts upon access for women seeking an early termination of pregnancy. There are no systematic reviews from a health services perspective to help direct health planners and policy makers to improve access comprehensive medical and early surgical abortion in high income countries. This review therefore aims to identify quality studies of abortion services to provide insight into how access to services can be improved in Australia. We undertook a structured search of six bibliographic databases and hand-searching to ascertain peer reviewed primary research in English between 2005 and 2015. Qualitative and quantitative study designs were deemed suitable for inclusion. A deductive content analysis methodology was employed to analyse selected manuscripts based upon a framework we developed to examine access to early abortion services. This review identified the dimensions of access to surgical and medical abortion at clinic or hospital-outpatient based abortion services, as well as new service delivery approaches utilising a remote telemedicine approach. A range of factors, mostly from studies in the United Kingdom and United States of America were found to facilitate improved access to abortion, in particular, flexible service delivery approaches that provide women with cost effective options and technology based services. Standards, recommendations and targets were also identified that provided services and providers with guidance regarding the quality of abortion care. Key insights for service delivery in Australia include the: establishment of standards, provision of choice of procedure, improved provider education and training and the expansion of telemedicine for medical

  11. Environmental and climatic changes during Valanginian (Early Cretaceous) perturbations of the carbon cycle

    Science.gov (United States)

    Kujau, A.; Heimhofer, U.; Hochuli, P. A.; Schouten, S.; Thierry, A.; Morales, C.; Mutterlose, J.

    2011-12-01

    After a long-lasting period of relatively stable conditions during the late Jurassic to earliest Cretaceous, the Valanginian was a time of climatic and environmental perturbations. Proposed changes include fluctuations in atmospheric pCO2, an accelerated hydrologic cycling, a cooling phase, and changes in composition and abundances of the marine fauna. A prominent perturbation of the global carbon cycle is documented in a globally recorded positive δ13C shift. Widespread storage of Corg-rich sediments in ocean basins, probably accompanied by anoxic conditions has long been supposed to explain for the positive carbon isotope anomaly. However, no widespread deposition of black shales has been shown for the Valanginian. Research on the Valanginian carbon cycle has focused on marine environmental changes, while studies on continental archives are scarce. This study deals with stable isotope chemostratigraphy, spore-pollen assemblages, palynofacies, and organic geochemistry of two successions located in the northwestern Tethyan realm (Vocontian Basin, SE France) and the Carpathian seaway (Polish Trough, central Poland). For both sites no evidence for anoxic conditions in the form of the occurrence of specific biomarkers like isoreniratene are found. Spore-pollen assemblages from both localities show many similarities in terms of composition, diversity and abundances of taxa. Both are dominated by conifer pollen and fern spores. During the initial phase of the δ13C shift the palynological compositions of both sites are quite diverging. Here, the French site is characterized by a decrease in spore abundances not being observed for the Polish site. This is followed by a peak in fern spores for both sites. Bulk Corg and algal-derived pristane and phytane follow the positive isotope shift of Ccarb with a lead of ~200 kyrs. Land plant derived long chain C27 n-alkanes for the Vocontian Basin as well show this positive shift while for the site at the Carpathian seaway the

  12. Molecular Ultrasound Imaging of Early Vascular Response in Prostate Tumors Irradiated with Carbon Ions

    Directory of Open Access Journals (Sweden)

    Moritz Palmowski

    2009-09-01

    Full Text Available Individualized treatments with combination of radiotherapy and targeted drugs require knowledge about the behavior of molecular targets after irradiation. Angiogenic marker expression has been studied after conventional radiotherapy, but little is known about marker response to charged particles. For the very first time, we used molecular ultrasound imaging to intraindividually track changes in angiogenic marker expression after carbon ion irradiation in experimental tumors. Expression of intercellular adhesion molecule-1 (ICAM-1 and of αvβ3-integrin in subcutaneous AT-1 prostate cancers in rats treated with carbon ions (16 Gy was studied using molecular ultrasound and immunohistochemistry. For this purpose, cyanoacrylate microbubbles were synthesized and linked to specific ligands. The accumulation of targeted microbubbles in tumors was quantified before and 36 hours after irradiation. In addition, tumor vascularization was analyzed using volumetric Doppler ultrasound. In tumors, the accumulation of targeted microbubbles was significantly higher than in nonspecific ones and could be inhibited competitively. Before irradiation, no difference in binding of αvβ3-integrin-specific or ICAM-1-specific microbubbles was observed in treated and untreated animals. After irradiation, however, treated animals showed a significantly higher binding of αvβ3-integrin-specific microbubbles and an enhanced binding of ICAM-1-specific microbubbles than untreated controls. In both groups, a decrease in vascularization occurred during tumor growth, but no significant difference was observed between irradiated and nonirradiated tumors. In conclusion, carbon ion irradiation upregulates ICAM-1 and αvβ3-integrin expression in tumor neovasculature. Molecular ultrasound can indicate the regulation of these markers and thus may help to identify the optimal drugs and time points in individualized therapy regimens.

  13. The role of Fe and Ni for s-process nucleosynthesis in the early Universe and for innovative nuclear technologies

    CERN Multimedia

    Manousos, A; Heil, M; Plag, R

    The early universe was enriched in heavy elements by massive stars via their s- and r-process contributions. Ultra metal-poor stars were found to show abundance patterns that scale exactly with the solar r component. While this holds exactly for elements heavier than barium, there is still confusion about significant discrepancies in the mass region below A ${\\leq}$ 120. It is known that massive stars contribute significantly to the abundances between Fe and Zr. This so-called weak s-process component was found to exhibit large uncertainties due to the poorly known cross sections, especially in the Fe- i region. In view of this problem it is proposed to perform accurate state-of-the art measurements on highly enriched samples of the stable Fe and Ni isotopes at the n_TOF facility. Transformation of these results into significantly improved stellar cross section rates will allow to disentangle the s and r contributions observed in the oldest stars for a reliable comparison with galactic chemical evolution mode...

  14. First Identification of Direct Collapse Black Hole Candidates in the Early Universe in CANDELS/GOODS-S

    CERN Document Server

    Pacucci, Fabio; Grazian, Andrea; Fiore, Fabrizio; Giallongo, Emanuele

    2016-01-01

    The first black hole seeds, formed when the Universe was younger than 500 Myr, are recognized to play an important role for the growth of early (z ~ 7) super-massive black holes. While progresses have been made in understanding their formation and growth, their observational signatures remain largely unexplored. As a result, no detection of such sources has been confirmed so far. Supported by numerical simulations, we present a novel photometric method to identify black hole seed candidates in deep multi-wavelength surveys. We predict that these highly-obscured sources are characterized by a steep spectrum in the infrared (1.6-4.5 micron), i.e. by very red colors. The method selects the only 2 objects with a robust X-ray detection found in the CANDELS/GOODS-S survey with a photometric redshift z > 6. Fitting their infrared spectra only with a stellar component would require unrealistic star formation rates (>2000 solar masses per year). To date, the selected objects represent the most promising black hole see...

  15. Spatially Extended 21 cm Signal from Strongly Clustered Uv and X-Ray Sources in the Early Universe

    Science.gov (United States)

    Ahn, Kyungjin; Xu, Hao; Norman, Michael L.; Alvarez, Marcelo A.; Wise, John H.

    2015-03-01

    We present our prediction for the local 21 cm differential brightness temperature (δTb) from a set of strongly clustered sources of Population III (Pop III) and II (Pop II) objects in the early universe, by a numerical simulation of their formation and radiative feedback. These objects are located inside a highly biased environment, which is a rare, high-density peak (“Rarepeak”) extending to ∼7 comoving Mpc. We study the impact of ultraviolet and X-ray photons on the intergalactic medium (IGM) and the resulting δTb, when Pop III stars are assumed to emit X-ray photons by forming X-ray binaries very efficiently. We parameterize the rest-frame spectral energy distribution of X-ray photons, which regulates X-ray photon-trapping, IGM-heating, secondary Lyα pumping and the resulting morphology of δTb. A combination of emission (δTb > 0) and absorption (δTb Frequency Array, Murchison Widefield Array, Precision Array for Probing the Epoch of Reionization) of such rare peaks is found to be difficult due to the rarity of these peaks, and the contribution only by these rare peaks to the total power spectrum remains subdominant compared to that by all astrophysical sources.

  16. Simulating the formation of massive seed black holes in the early Universe. III: The influence of X-rays

    CERN Document Server

    Glover, Simon C O

    2016-01-01

    The direct collapse black hole (DCBH) model attempts to explain the observed number density of supermassive black holes in the early Universe by positing that they grew from seed black holes with masses of $10^{4}$-$10^{5} \\: {\\rm M_{\\odot}}$ that formed by the quasi-isothermal collapse of gas in metal-free protogalaxies cooled by atomic hydrogen emission. For this model to work, H$_{2}$ formation must be suppressed in at least some of these systems by a strong extragalactic radiation field. The predicted number density of DCBH seeds is highly sensitive to the minimum value of the ultraviolet (UV) flux required to suppress H$_{2}$ formation, $J_{\\rm crit}$. In this paper, we examine how the value of $J_{\\rm crit}$ varies as we vary the strength of a hypothetical high-redshift X-ray background. We confirm earlier findings that when the X-ray flux $J_{\\rm X}$ is large, the critical UV flux scales as $J_{\\rm crit} \\propto J_{\\rm X}^{1/2}$. We also carefully explore possible sources of uncertainty arising from ho...

  17. The Origin of Dust in the Early Universe: Probing the Star Formation History of Galaxies by Their Dust Content

    Science.gov (United States)

    Dwek, Eli; Cherchneff, Isabelle

    2010-01-01

    Two distinct scenarios for the origin of the approximately 4 x 10(exp 8) Solar Mass of dust observed in the high-redshift (z = 6.4) quasar J1148+5251 have been proposed. The first assumes that this galaxy is much younger than the age of the universe at that epoch so that only supernovae, could have produced this dust. The second scenario assumes a significantly older galactic age, so that the dust could have formed in lower-mass AGB stars. Presenting new integral solutions for the chemical evolution of metals and dust in galaxies, we offer a critical evaluation of these two scenarios. ^N;"(,, show that the AGB scenario is sensitive to the details of the galaxy's star formation history (SFH), which must consist of an early intense starburst followed by a period of low stellar activity. The presence or absence of massive amounts of dust in high-redshift galaxies can therefore be used to infer their SFH. However, a problem with the AGB scenario is that it produces a stellar mass that is significantly larger than the inferred dynamical mass of J1148+5251, an yet unresolved discrepancy. If this problem persists, then additional sites for the growth or formation of dust, such as molecular clouds or dense clouds around active galactic nuclei, must be considered.

  18. Massive impact-induced release of carbon and sulfur gases in the early Earth's atmosphere

    Science.gov (United States)

    Marchi, S.; Black, B. A.; Elkins-Tanton, L. T.; Bottke, W. F.

    2016-09-01

    Recent revisions to our understanding of the collisional history of the Hadean and early-Archean Earth indicate that large collisions may have been an important geophysical process. In this work we show that the early bombardment flux of large impactors (>100 km) facilitated the atmospheric release of greenhouse gases (particularly CO2) from Earth's mantle. Depending on the timescale for the drawdown of atmospheric CO2, the Earth's surface could have been subject to prolonged clement surface conditions or multiple freeze-thaw cycles. The bombardment also delivered and redistributed to the surface large quantities of sulfur, one of the most important elements for life. The stochastic occurrence of large collisions could provide insights on why the Earth and Venus, considered Earth's twin planet, exhibit radically different atmospheres.

  19. The conservative behavior of dissolved organic carbon in surface waters of the southern Chukchi Sea, Arctic Ocean, during early summer

    Science.gov (United States)

    Tanaka, Kazuki; Takesue, Nobuyuki; Nishioka, Jun; Kondo, Yoshiko; Ooki, Atsushi; Kuma, Kenshi; Hirawake, Toru; Yamashita, Youhei

    2016-01-01

    The spatial distribution of dissolved organic carbon (DOC) concentrations and the optical properties of dissolved organic matter (DOM) determined by ultraviolet-visible absorbance and fluorescence spectroscopy were measured in surface waters of the southern Chukchi Sea, western Arctic Ocean, during the early summer of 2013. Neither the DOC concentration nor the optical parameters of the DOM correlated with salinity. Principal component analysis using the DOM optical parameters clearly separated the DOM sources. A significant linear relationship was evident between the DOC and the principal component score for specific water masses, indicating that a high DOC level was related to a terrigenous source, whereas a low DOC level was related to a marine source. Relationships between the DOC and the principal component scores of the surface waters of the southern Chukchi Sea implied that the major factor controlling the distribution of DOC concentrations was the mixing of plural water masses rather than local production and degradation. PMID:27658444

  20. Environment and ecology of East Asian dinosaurs during the Early Cretaceous inferred from stable oxygen and carbon isotopes in apatite

    Science.gov (United States)

    Amiot, Romain; Wang, Xu; Zhou, Zhonghe; Wang, Xiaolin; Lécuyer, Christophe; Buffetaut, Eric; Fluteau, Frédéric; Ding, Zhongli; Kusuhashi, Nao; Mo, Jinyou; Philippe, Marc; Suteethorn, Varavudh; Wang, Yuanqing; Xu, Xing

    2015-02-01

    During the cold Late Barremian-Early Albian interval, terrestrial environments in East Asia were populated by rich and diverse vertebrate faunas characterized by a strong provincialism. The latitudinal gradient of temperature and the existence of geographic barriers likely accounted for some aspects of this heterogeneous distribution of faunas. Other factors, however, such as local environmental conditions and interactions within vertebrate communities, which could have influenced their distribution, have not yet been fully identified and understood. Therefore, new and published oxygen and carbon isotope compositions of apatite from Chinese and Thai reptiles (dinosaurs, crocodilians and turtles) have been analyzed and interpreted in terms of ecology, local air temperature and precipitation amounts. Differences in carbon and oxygen isotope compositions between various groups of sympatric plant-eating dinosaurs (sauropods, ornithopods and ceratopsians) indicate food resources partitioning among them most likely to avoid competition. Mid-latitude environments, where the Jehol Biota flourished, were submitted to cool temperate climatic conditions with Mean Air Temperature (MAT) of 10 ± 4 °C and Mean Annual Precipitations (MAP) of about 600 mm/yr compatible with the existence of forest environments. By contrast, sub-tropical regions, characterized by MAT of about 20-25 °C were either submitted to high amounts of seasonal precipitations (of about 1200 mm/yr in Thailand) or to significant aridity (MAP of about 400 mm/yr in South China). This difference in precipitation regime between Thailand and South China may be attributed to the occurrence of the Coastal Cordillera extending along the East margin of the South China block. These mountain ranges likely prevented humid air masses from the Pacific to penetrate some parts of South China, thus generating a "rain shadow effect". Mosaic environments characterizing East Asia during the Late Early Cretaceous may have acted

  1. The role of remnant trees in carbon sequestration, vegetation structure and tree diversity of early succession regrowing fallows in eastern Sierra Leone

    DEFF Research Database (Denmark)

    Cuni Sanchez, Aida; Lindsell, Jeremy A.

    2017-01-01

    and tree diversity increased significantly with fallow age. Remnant tree presence affected significantly tree diversity, species dominance and above-ground carbon stocks, but not vegetation structure (stem density, basal area). Number of remnant trees and number of species of remnant trees were also...... by encroachment and forest degradation. We studied 99 (20-m-radius) plots aged 2-10 years with and without remnant trees and compared their above-ground carbon stocks, vegetation structure (stem density, basal area) and tree diversity. Above-ground carbon stocks, stem density, basal area, species richness......, this is the first study on early succession regrowing fallows in West Africa....

  2. Wear Characterization of Carbon Nanotubes Reinforced Acetal Spur, Helical, Bevel and Worm Gears Using a TS Universal Test Rig

    Science.gov (United States)

    Yousef, Samy; Osman, T. A.; Abdalla, Abdelrahman H.; Zohdy, Gamal A.

    2015-12-01

    Although the applications of nanotechnologies are increasing, there remains a significant barrier between nanotechnology and machine element applications. This work aims to remove this barrier by blending carbon nanotubes (CNT) with common types of acetal polymer gears (spur, helical, bevel and worm). This was done by using adhesive oil (paraffin) during injection molding to synthesize a flange and short bars containing 0.02% CNT by weight. The flanges and short bars were machined using hobbing and milling machines to produce nanocomposite polymer gears. Some defects that surfaced in previous work, such as the appearance of bubbles and unmelted pellets during the injection process, were avoided to produce an excellent dispersion of CNT in the acetal. The wear resistances of the gears were measured by using a TS universal test rig using constant parameters for all of the gears that were fabricated. The tests were run at a speed of 1420 rpm and a torque of 4 Nm. The results showed that the wear resistances of the CNT/acetal gears were increased due to the addition of CNT, especially the helical, bevel and worm gears.

  3. How fresh is maple syrup? Sugar maple trees mobilize carbon stored several years previously during early springtime sap-ascent.

    Science.gov (United States)

    Muhr, Jan; Messier, Christian; Delagrange, Sylvain; Trumbore, Susan; Xu, Xiaomei; Hartmann, Henrik

    2016-03-01

    While trees store substantial amounts of nonstructural carbon (NSC) for later use, storage regulation and mobilization of stored NSC in long-lived organisms like trees are still not well understood. At two different sites with sugar maple (Acer saccharum), we investigated ascending sap (sugar concentration, δ(13) C, Δ(14) C) as the mobilized component of stored stem NSC during early springtime. Using the bomb-spike radiocarbon approach we were able to estimate the average time elapsed since the mobilized carbon (C) was originally fixed from the atmosphere and to infer the turnover time of stem storage. Sites differed in concentration dynamics and overall δ(13) C, indicating different growing conditions. The absence of temporal trends for δ(13) C and Δ(14) C indicated sugar mobilization from a well-mixed pool with average Δ(14) C consistent with a mean turnover time (TT) of three to five years for this pool, with only minor differences between the sites. Sugar maple trees hence appear well buffered against single or even several years of negative plant C balance from environmental stress such as drought or repeated defoliation by insects. Manipulative investigations (e.g. starvation via girdling) combined with Δ(14) C measurements of this mobilized storage pool will provide further new insights into tree storage regulation and functioning.

  4. Major perturbations in the global carbon cycle and photosymbiont-bearing planktic foraminifera during the early Eocene

    Science.gov (United States)

    Luciani, Valeria; Dickens, Gerald R.; Backman, Jan; Fornaciari, Eliana; Giusberti, Luca; Agnini, Claudia; D'Onofrio, Roberta

    2016-04-01

    A marked switch in the abundance of the planktic foraminiferal genera Morozovella and Acarinina occurred at low-latitude sites near the start of the Early Eocene Climatic Optimum (EECO), a multi-million-year interval when Earth surface temperatures reached their Cenozoic maximum. Stable carbon and oxygen isotope data of bulk sediment are presented from across the EECO at two locations: Possagno in northeast Italy and Deep Sea Drilling Project (DSDP) Site 577 in the northwest Pacific. Relative abundances of planktic foraminifera are presented from these two locations, as well as from Ocean Drilling Program (ODP) Site 1051 in the northwest Atlantic. All three sections have good stratigraphic markers, and the δ13C records at each section can be correlated amongst each other and to δ13C records at other locations across the globe. These records show that a series of negative carbon isotope excursions (CIEs) occurred before, during and across the EECO, which is defined here as the interval between the J event and the base of Discoaster sublodoensis. Significant though ephemeral modifications in planktic foraminiferal assemblages coincide with some of the short-term CIEs, which were marked by increases in the relative abundance of Acarinina, similar to what happened across established hyperthermal events in Tethyan settings prior to the EECO. Most crucially, a temporal link exists between the onset of the EECO, carbon cycle changes during this time and the decline in Morozovella. Possible causes are manifold and may include temperature effects on photosymbiont-bearing planktic foraminifera and changes in ocean chemistry.

  5. Early diagenetic growth of carbonate concretions in the upper Doushantuo Formation in South China and their significance for the assessment of hydrocarbon source rock

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Mineralogical and textural characteristics and organic carbon composition of the carbonate concretions from the upper Doushantuo Formation (ca. 551 Ma) in the eastern Yangtze Gorge area reveal their early diagenetic (shallow) growth in organic-rich shale. High organic carbon content (up to 10%) and abundance of framboidal pyrites in the hosting shale suggest an anoxic or euxinic depositional environment. Well-preserved cardhouse clay fabrics in the concretions suggest their formation at 0-3 m burial depth, likely associated with microbial decomposition of organic matter and anaerobic oxidation of methane. Gases through decomposition of organic matter and/or from methanogenesis created bubbles and cavities, and anaerobic methane oxidation at the sulfate reduction zone resulted in carbonate precipitation, filling in bubbles and cavities to form spherical structures of the concretions. Rock pyrolysis analyses show that the carbonate concretions have lower total organic carbon (TOC) content but higher effective carbon than those in the host rocks. This may be caused by enclosed organic matter in pores of the concretions so that organic matter was protected from further modification during deep burial and maintained high hydrocarbon generating potential even in over-matured source rock. As a microbialite sensu latu, concretions have special growth conditions and may provide important information on the microbial activities in depositional and early burial environments.

  6. Biogeochemical Cycles of Carbon and Sulfur on Early Earth (and on Mars?)

    Science.gov (United States)

    DesMarais, D. J.

    2004-01-01

    The physical and chemical interactions between the atmosphere, hydrosphere, geosphere and biosphere can be examined for elements such as carbon (C) and sulfur (S) that have played central roles for both life and the environment. The compounds of C are highly important, not only as organic matter, but also as atmospheric greenhouse gases, pH buffers in seawater, oxidation-reduction buffers virtually everywhere, and key magmatic constituents affecting plutonism and volcanism. S assumes important roles as an oxidation-reduction partner with C and Fe in biological systems, as a key constituent in magmas and volcanic gases, and as a major influence upon pH in certain environments. These multiple roles of C and S interact across a network of elemental reservoirs interconnected by physical, chemical and biological processes. These networks are termed biogeochemical C and S cycles.

  7. Contribution of Oxygenic Photosynthesis to Palaeo-Oceanic Organic Carbon Sink Fluxes in Early Cambrian Upper Yangtze Shallow Sea:Evidence from Black Shale Record

    Institute of Scientific and Technical Information of China (English)

    Kunyu Wu; Tingshan Zhang; Yang Yang; Yuchuan Sun; Daoxian Yuan

    2016-01-01

    ABSTRACT:The extensive transgression that occurred on the Yangtze Plate in Early Cambrian led to a massive organic carbon pool in the Niutitang Formation. A black shale core section from 3 251.08 to 3 436.08 m beneath the Earth’s surface was studied to estimate the contribution of oxygenic photosyn-thesis to organic carbon sink fluxes in Early Cambrian Upper Yangtze shallow sea. Results indicate that the oxygenic photosynthesis played the most important role in carbon fixation in Early Cambrian. Or-ganic carbon sink was mainly contributed by photosynthetic microorganisms, e.g., cyanobacteria, algae and archaea. The Niutitang Formation was formed in a deep anoxic marine shelf sedimentary envi-ronment at a sedimentation rate of ~0.09±0.03 mm/yr. The initial TOC abundance in Niutitang shale ranged from 0.18%to 7.09%, with an average of 2.15%. In accordance with the sedimentation rate and initial TOC abundance, organic carbon sink fluxes were calculated and found to range from 0.21 to 8.10×103 kg/km2·yr-1, especially the organic carbon sink fluxes in depth between 3 385 and 3 470 m range from 3.80 to 8.10×103 kg/km2·yr-1, with an average of~6.03×103 kg/km2·yr-1, which is much high-er than that of contemporary marine sediments. The organic carbon sink fluxes of Niutitang shale are equal to 0.56 to 21.61×103 kg/km2·yr-1 net oxygen emitted into the Early Cambrian ocean and atmos-phere, this emitted oxygen may have significantly promoted the oxygen level of the Earth’s surface and diversification of metazoans.

  8. Early Pleistocene short-term intermediate water mass variability influences Carbonate Mound development in the NE Atlantic (IODP Site 1317)

    Science.gov (United States)

    Raddatz, J.; Rüggeberg, A.; Margreth, S.; Liebetrau, V.; Dullo, W.; Eisenhauer, A.; Iodp Expedition 307 Scientific Party

    2010-12-01

    The Integrated Ocean Drilling Program (IODP) Exp. 307 drilled the 155 m high Challenger Mound in the Porcupine Seabight (SW off Ireland) in order to investigate for the first time sediments from the base of a giant carbonate mound. In this study we focus on sediments from the base of Challenger Mound (Porcupine Seabight, SW off Ireland) IODP Site 1317 in high resolution. The mound initiation and start-up phase coincides with the intensification of the Northern Hemisphere Glaciation (INHG) at around 2.6 Ma. Further carbonate mound development seems to be strongly dependent on rapid changes in paleoceanographic and climatic conditions at the Pliocene-Pleistocene boundary, especially characterized and caused by the interaction of intermediate water masses, the Mediterranean Outflow Water (MOW), the Eastern North Atlantic Water (ENAW) and the influence of Southern Component Water (SCW). This study is based on well-established proxies such as δ18O and δ13C of planktonic (Globigerina bulloides) and benthic foraminifera (Fontbotia wuellerstorfi, Discanomalina coronata, Lobatula lobatula, Lobatula antarctica, and Planulina ariminensis) as well as grain size parameters to identify the paleoenvironmental and paleoecological setting favourable for the initial coral colonization on the mound. Stable oxygen and carbon isotope records of benthic foraminiferal species indicate that L. lobatula provides a reliable isotopic signature for paleoenvironmental reconstructions. In particular, δ18O values of L. lobatula indicate initial mound growth started in a glacial mode with moderate excursions in δ18O values. Bottom water temperatures, calculated using standard equations based on δ18O of foraminiferal tests, range between 7 and 11°C, consistent with the known temperature range conducive for cold-water coral growth and development. Bottom currents transporting intermediate water masses of southern origin (Mediterranean, Bay of Biscay) enhanced at 2.6 Ma supporting first coral

  9. Self-healing of Early Age Cracks in Cement-based Materials by Mineralization of Carbonic Anhydrase Microorganism

    Directory of Open Access Journals (Sweden)

    Chunxiang eQian

    2015-11-01

    Full Text Available This research investigated the self-healing potential of early age cracks in cement-based materials incorporating the bacteria which can produce carbonic anhydrase. Cement-based materials specimens were pre-cracked at the age of 7, 14, 28, 60 days to study the repair ability influenced by cracking time, the width of cracks were between 0.1 and 1.0 mm to study the healing rate influenced by width of cracks. The experimental results indicated that the bacteria showed excellent repairing ability to small cracks formed at early age of 7 days, cracks below 0.4 mm was almost completely closed. The repair effect reduced with the increasing of cracking age. Cracks width influenced self-healing effectiveness significantly. The transportation of CO2 and Ca2+ controlled the self-healing process. The computer simulation analyses revealed the self-healing process and mechanism of microbiologically precipitation induced by bacteria and the depth of precipitated CaCO3 could be predicted base on valid Ca2+.

  10. Comparison of Efficacy of Carbon Dioxide (CO2) Laser with Cutting Diathermy in Surgical Excision of Early Carcinoma Tongue.

    Science.gov (United States)

    Rashid, Muhammad; Hashmi, Muhammad Ali; Maqbool, Shahzad; Dastigir, Majid

    2015-10-01

    To compare the efficacy of carbon dioxide (CO(2)) laser with cutting diathermy as a cutting device in surgical excision of early carcinoma tongue. Experimental study. Combined Military Hospital (CMH), Rawalpindi and CMH, Lahore, from July 2008 to July 2011. Twenty two biopsy proven cases of T(1) and early T(2) squamous cell carcinoma of tongue were divided in two equal groups of 11 each labeled as A and B. Tumor was excised by CO(2) laser in group A while cutting diathermy was done in group B. For both groups tumor excision time, per-operative blood loss, postoperative oral swelling and pain was recorded. Excision time of tumor was assessed in minutes and amount of blood loss in milliliters till complete hemostasis after removal of primary tumor. Postoperatively patients were assessed on 12 hourly basis for 48 hours for pain. Pain was analyzed on visual analogue score 1 - 10. Oral swelling was assessed once after 24 hours and labeled as mild, moderate and severe. Independent sample t-test was applied for analysis of excision time, postoperative pain and per-operative blood loss for both groups. Postoperative swelling was analyzed using Fisher's exact test. P-value of laser than electrocautery in terms of postoperative morbidity, per-operative blood loss, postoperative pain and oral swelling.

  11. Early Embryogenesis of Brown Alga Fucus vesiculosus L. is Characterized by Significant Changes in Carbon and Energy Metabolism.

    Science.gov (United States)

    Tarakhovskaya, Elena; Lemesheva, Valeriya; Bilova, Tatiana; Birkemeyer, Claudia

    2017-09-09

    Brown algae have an important role in marine environments. With respect to their broad distribution and importance for the environment and human use, brown algae of the order Fucales in particular became a model system for physiological and ecological studies. Thus, several fucoids have been extensively studied for their composition on the molecular level. However, research of fucoid physiology and biochemistry so far mostly focused on the adult algae, so a holistic view on the development of these organisms, including the crucial first life stages, is still missing. Therefore, we employed non-targeted metabolite profiling by gas chromatography coupled to mass spectrometry to create a non-biased picture of the early development of the fucoid alga Fucus vesiculosus. We found that embryogenic physiology was mainly dominated by a tight regulation of carbon and energy metabolism. The first dramatic changes of zygote metabolism started within 1 h after fertilization, while metabolism of 6-9 days old embryos appeared already close to that of an adult alga, indicated by the intensive production of secondary metabolites and accumulation of mannitol and citric acid. Given the comprehensive description and analysis we obtained in our experiments, our results exhibit an invaluable resource for the design of further experiments related to physiology of early algal development.

  12. Early spring, severe frost events, and drought induce rapid carbon loss in high elevation meadows.

    Directory of Open Access Journals (Sweden)

    Chelsea Arnold

    Full Text Available By the end of the 20th century, the onset of spring in the Sierra Nevada mountain range of California has been occurring on average three weeks earlier than historic records. Superimposed on this trend is an increase in the presence of highly anomalous "extreme" years, where spring arrives either significantly late or early. The timing of the onset of continuous snowpack coupled to the date at which the snowmelt season is initiated play an important role in the development and sustainability of mountain ecosystems. In this study, we assess the impact of extreme winter precipitation variation on aboveground net primary productivity and soil respiration over three years (2011 to 2013. We found that the duration of snow cover, particularly the timing of the onset of a continuous snowpack and presence of early spring frost events contributed to a dramatic change in ecosystem processes. We found an average 100% increase in soil respiration in 2012 and 2103, compared to 2011, and an average 39% decline in aboveground net primary productivity observed over the same time period. The overall growing season length increased by 57 days in 2012 and 61 days in 2013. These results demonstrate the dependency of these keystone ecosystems on a stable climate and indicate that even small changes in climate can potentially alter their resiliency.

  13. The role of stage in teacher training for early childhood education: a debate, the University of Florence and the University of Vale do Itajaí models

    Directory of Open Access Journals (Sweden)

    Claudete Bonfanti

    2016-07-01

    Full Text Available The paper discusses the stage role in teacher training for early childhood education. Are research subjects the trainees of the Faculty of Education at the University of Vale do Itajaí (Brazil in 2014, and Corso di Laurea in Scienze della Formazione Primaria indirizzo Scuola dell’infanzia dell’Università di Firenze (Italy in 2015. The study is guided in qualitative research (Bogdan & Biklen, 1994. Interviews and documents of both courses were analyzed. We seek to support the theoretical studies (Bondioli & Ferrari, 2008; Calvani, 2014; Catarsi, 2014; Catarsi & Fortunati, 2012; Gomes, 2009; Pimenta & Lima, 2012; Silva, 2014. The analysis indicates that sometimes the students do not understand the connection between theory and practice, referring to the internship in the child education. It is considered that overcoming the dichotomy between theory and practice constitutes weakness to be overcome in the initial training of future teachers. We did not intend to compare the two contexts, but this paper is a suggestion for future researchers to continue the debate on the weaknesses identified in this research.O papel do estágio na formação de professores para a educação infantil: em debate, o modelo da Università degli Studi di Firenze e o da Universidade do Vale do ItajaíO trabalho discute o papel do estágio na formação dos professores para a educação infantil. São sujeitos da pesquisa as estagiárias do curso de Pedagogia da Universidade do Vale do Itajaí (Brasil, em 2014, e do Corso di Laurea in Scienze della Formazione Primaria indirizzo Scuola dell’infanzia dell’Università di Firenze (Italia, em 2015. O estudo pauta-se na abordagem qualitativa de pesquisa (Bogdan & Biklen, 1994 e foram analisados entrevistas e documentos de ambos os cursos. Buscou-se respaldo nos estudos teóricos de (Bondioli & Ferrari, 2008; Calvani, 2014; Catarsi, 2014; Catarsi & Fortunati, 2012; Gomes, 2009; Pimenta & Lima, 2012; Silva, 2014. A an

  14. How Much of the Science of Climate Change Does the Public Really Understand? Evaluation of University Students' Ideas on the Carbon Cycle

    Science.gov (United States)

    Madsen, J.; Gerhman, E.; Ford, D.

    2007-12-01

    To be able to effectively bring the science of climate change to educational audiences, it is important to have an understanding of the learners' prior knowledge of the scientific topics involved in the study of climate change. We have evaluated the prior knowledge of the carbon cycle and how human activities affect this cycle using a cohort of university-level students, primarily freshman and sophomore elementary education majors. The movement of carbon through the earth's atmosphere, biosphere, hydrosphere, and lithosphere is a fundamental biogeochemical cycle that influences earth's climate. As a pre-assessment of content knowledge, approximately 170 students enrolled in an introductory-level earth science course were asked to describe what a standard diagram illustrating the carbon cycle shows about how carbon cycles on earth and how energy is involved in this cycle. They were then asked to describe how human activities might affect the carbon cycle. This pre-assessment, assigned and submitted as an on-line activity, was given during the middle portion of the semester before topics directly pertaining to climate change were addressed in the course. These prior knowledge assessments were collected as part of an integrated research project funded by the National Science Foundation designed to study how teachers' science content and pedagogical knowledge develops as they move from university student to practicing K-8 teacher. The initial evaluation of the pre-assessments focused on the identification of alternative conceptions of the carbon cycle and of how human activities affected the cycle. These alternative conceptions were grouped into broad categories. The results show a remarkable lack of understanding of the some of the basic components of the carbon cycle and of how humans may affect this cycle. For example, there was a general lack of understanding of how carbon moves between reservoirs. A popular alternative conception was that carbon, like water, is

  15. The Early Development of the Open University: Report of the Vice-Chancellor January 1969-December 1970.

    Science.gov (United States)

    Open Univ., Walton, Bletchley, Bucks (England).

    This report concerns the extablishment and development of the British Open University. Contents include the descriptions of: the development of the institution; staffing the open university; development of the Milton Keynes Campus; undergraduate course development; regional organization; demand for open university courses; development, production,…

  16. Assessment of Early Leak-Detection Capabilities at a Commercial-Scale Carbon Capture and Storage Site

    Science.gov (United States)

    Williams, M. D.; Vermeul, V. R.; Oostrom, M.; Porse, S.

    2014-12-01

    In cooperation with the U.S. Department of Energy (DOE), a large Midwest carbon capture and storage (CCS) project will upgrade a power plant with oxy-combustion technology to capture approximately 1.1 million metric tons (MMT) of CO2 each year. This project will design and construct a first-of-its-kind, near-zero emissions coal-fueled power plant that incorporates CCS. The project will implement a suite of monitoring technologies that includes early-leak-detection monitoring directly above the primary confining zone in regions of increased leakage potential (e.g., near wells that penetrate the caprock). In support of early leak-detection monitoring systems design, numerical models were developed and used to evaluate the relative value of various leak detection metrics over a range of hypothetical leakage scenarios. This preliminary modeling evaluation was based on a simplified model that assumed uniform properties for each model layer and interrogated both pressure and geochemical response in the first permeable interval overlying the primary confining zone. Simulation results indicate that pressure is likely to be the earliest indicator of leakage, given the rapid and areally extensive nature of this response. Simulated geochemical signals are much more localized and take much longer to develop than the pressure responses. Because of the buoyancy effect associated with supercritical CO2 (scCO2), early leak-detection monitoring for these leakage scenarios would be best achieved through monitoring in the upper portion of the interval near the contact with overlying low-permeability materials. Conversely, monitoring for geochemical signals associated with brine leakage exhibited less lateral spread than for scCO2 cases and detection of leakage would be best achieved through monitoring at the base of the interval. Results from these preliminary models for a suite of leakage scenarios and monitoring location distances will be presented. These preliminary models will be

  17. SPATIALLY EXTENDED 21 cm SIGNAL FROM STRONGLY CLUSTERED UV AND X-RAY SOURCES IN THE EARLY UNIVERSE

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Kyungjin [Department of Earth Sciences, Chosun University, Gwangju, 501-759 (Korea, Republic of); Xu, Hao; Norman, Michael L. [Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (United States); Alvarez, Marcelo A. [Canadian Institute for Theoretical Astrophysics, 60 St. George St., Toronto, ON M5S 3H8 (Canada); Wise, John H., E-mail: kjahn@chosun.ac.kr [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332 (United States)

    2015-03-20

    We present our prediction for the local 21 cm differential brightness temperature (δT{sub b}) from a set of strongly clustered sources of Population III (Pop III) and II (Pop II) objects in the early universe, by a numerical simulation of their formation and radiative feedback. These objects are located inside a highly biased environment, which is a rare, high-density peak (“Rarepeak”) extending to ∼7 comoving Mpc. We study the impact of ultraviolet and X-ray photons on the intergalactic medium (IGM) and the resulting δT{sub b}, when Pop III stars are assumed to emit X-ray photons by forming X-ray binaries very efficiently. We parameterize the rest-frame spectral energy distribution of X-ray photons, which regulates X-ray photon-trapping, IGM-heating, secondary Lyα pumping and the resulting morphology of δT{sub b}. A combination of emission (δT{sub b} > 0) and absorption (δT{sub b} < 0) regions appears in varying amplitudes and angular scales. The boost of the signal by the high-density environment (δ ∼ 0.64) and on a relatively large scale combines to make Rarepeak a discernible, spatially extended (θ ∼ 10′) object for 21 cm observation at 13 ≲ z ≲ 17, which is found to be detectable as a single object by SKA with integration time of ∼1000 hr. Power spectrum analysis by some of the SKA precursors (Low Frequency Array, Murchison Widefield Array, Precision Array for Probing the Epoch of Reionization) of such rare peaks is found to be difficult due to the rarity of these peaks, and the contribution only by these rare peaks to the total power spectrum remains subdominant compared to that by all astrophysical sources.

  18. Assessing offsets between the δ13C of sedimentary components and the global exogenic carbon pool across early Paleogene carbon cycle perturbations

    NARCIS (Netherlands)

    Sluijs, A.|info:eu-repo/dai/nl/311474748; Dickens, G.R.

    2012-01-01

    Negative stable carbon isotope excursions (CIEs) across the Paleocene–Eocene thermal maximum (PETM; ∼56 Ma) range between 2‰ and 7‰, even after discounting sections with truncated records. Individual carbon isotope records differ in shape and magnitude from variations in the global exogenic carbon

  19. Assessing offsets between the δ13C of sedimentary components and the global exogenic carbon pool across early Paleogene carbon cycle perturbations

    NARCIS (Netherlands)

    Sluijs, A.; Dickens, G.R.

    2012-01-01

    Negative stable carbon isotope excursions (CIEs) across the Paleocene–Eocene thermal maximum (PETM; ∼56 Ma) range between 2‰ and 7‰, even after discounting sections with truncated records. Individual carbon isotope records differ in shape and magnitude from variations in the global exogenic carbon c

  20. Reconstructing Changes in Deep Ocean Temperature and Global Carbon Cycle during the Early Eocene Warming Trend: High-Resolution Benthic Stable Isotope Records from the SE Atlantic.

    Science.gov (United States)

    Lauretano, V.; Zachos, J. C.; Lourens, L. J.

    2014-12-01

    From the late Paleocene to the early Eocene, Earth's surface temperatures generally rose, resulting in an increase of at least 5°C in the deep ocean and culminating in the Early Eocene Climatic Optimum (EECO). This long-term warming was punctuated by a series of short-lived global warming events known as "hyperthermals", of which the Paleocene-Eocene Thermal Maximum (PETM) represents the most extreme example. At least two other short-term episodes have been identified as hyperthermals: the ETM2 (or Elmo event) at about 53.7 Myr and the ETM3 (or X-event) at about 52.5 Myr. These transient events are marked by prominent carbon isotope excursions (CIEs), recorded in marine and continental sedimentary sequences and driven by fast and massive injections of 13C-depleted carbon into the ocean-atmosphere system. Recently, evidence has indicated the presence of a regular series of hyperthermal events following the peak in temperatures of the EECO. However, continuous records are needed to investigate short- and long- term changes in the climate system throughout the Early Eocene warming trend. Here, we present new high-resolution benthic stable isotope records of the Early Eocene from ODP Site 1263, (Walvis Ridge, SE Atlantic). The carbon and oxygen records document changes in deep-sea temperature and global carbon cycle encompassing the Early Eocene hyperthermal events and the EECO interval. The transition phase to the post-EECO events is distinct by the decoupling of carbon and oxygen isotopes on the long-term scale. Spectral and wavelet analyses suggest the influence of orbital forcing, specifically long and short eccentricity cycles.